xref: /linux/kernel/sched/fair.c (revision 36ae1c45b2cede43ab2fc679b450060bbf119f1b)
1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * Completely Fair Scheduling (CFS) Class (SCHED_NORMAL/SCHED_BATCH)
4  *
5  *  Copyright (C) 2007 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
6  *
7  *  Interactivity improvements by Mike Galbraith
8  *  (C) 2007 Mike Galbraith <efault@gmx.de>
9  *
10  *  Various enhancements by Dmitry Adamushko.
11  *  (C) 2007 Dmitry Adamushko <dmitry.adamushko@gmail.com>
12  *
13  *  Group scheduling enhancements by Srivatsa Vaddagiri
14  *  Copyright IBM Corporation, 2007
15  *  Author: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>
16  *
17  *  Scaled math optimizations by Thomas Gleixner
18  *  Copyright (C) 2007, Linutronix GmbH, Thomas Gleixner <tglx@kernel.org>
19  *
20  *  Adaptive scheduling granularity, math enhancements by Peter Zijlstra
21  *  Copyright (C) 2007 Red Hat, Inc., Peter Zijlstra
22  */
23 #include <linux/energy_model.h>
24 #include <linux/mmap_lock.h>
25 #include <linux/hugetlb_inline.h>
26 #include <linux/jiffies.h>
27 #include <linux/mm_api.h>
28 #include <linux/highmem.h>
29 #include <linux/spinlock_api.h>
30 #include <linux/cpumask_api.h>
31 #include <linux/lockdep_api.h>
32 #include <linux/softirq.h>
33 #include <linux/refcount_api.h>
34 #include <linux/topology.h>
35 #include <linux/sched/clock.h>
36 #include <linux/sched/cond_resched.h>
37 #include <linux/sched/cputime.h>
38 #include <linux/sched/isolation.h>
39 #include <linux/sched/nohz.h>
40 #include <linux/sched/prio.h>
41 
42 #include <linux/cpuidle.h>
43 #include <linux/interrupt.h>
44 #include <linux/memory-tiers.h>
45 #include <linux/mempolicy.h>
46 #include <linux/mutex_api.h>
47 #include <linux/profile.h>
48 #include <linux/psi.h>
49 #include <linux/ratelimit.h>
50 #include <linux/task_work.h>
51 #include <linux/rbtree_augmented.h>
52 
53 #include <asm/switch_to.h>
54 
55 #include <uapi/linux/sched/types.h>
56 
57 #include "sched.h"
58 #include "stats.h"
59 #include "autogroup.h"
60 
61 /*
62  * The initial- and re-scaling of tunables is configurable
63  *
64  * Options are:
65  *
66  *   SCHED_TUNABLESCALING_NONE - unscaled, always *1
67  *   SCHED_TUNABLESCALING_LOG - scaled logarithmically, *1+ilog(ncpus)
68  *   SCHED_TUNABLESCALING_LINEAR - scaled linear, *ncpus
69  *
70  * (default SCHED_TUNABLESCALING_LOG = *(1+ilog(ncpus))
71  */
72 unsigned int sysctl_sched_tunable_scaling = SCHED_TUNABLESCALING_LOG;
73 
74 /*
75  * Minimal preemption granularity for CPU-bound tasks:
76  *
77  * (default: 0.70 msec * (1 + ilog(ncpus)), units: nanoseconds)
78  */
79 unsigned int sysctl_sched_base_slice			= 700000ULL;
80 static unsigned int normalized_sysctl_sched_base_slice	= 700000ULL;
81 
82 __read_mostly unsigned int sysctl_sched_migration_cost	= 500000UL;
83 
84 static int __init setup_sched_thermal_decay_shift(char *str)
85 {
86 	pr_warn("Ignoring the deprecated sched_thermal_decay_shift= option\n");
87 	return 1;
88 }
89 __setup("sched_thermal_decay_shift=", setup_sched_thermal_decay_shift);
90 
91 /*
92  * For asym packing, by default the lower numbered CPU has higher priority.
93  */
94 int __weak arch_asym_cpu_priority(int cpu)
95 {
96 	return -cpu;
97 }
98 
99 /*
100  * The margin used when comparing utilization with CPU capacity.
101  *
102  * (default: ~20%)
103  */
104 #define fits_capacity(cap, max)	((cap) * 1280 < (max) * 1024)
105 
106 /*
107  * The margin used when comparing CPU capacities.
108  * is 'cap1' noticeably greater than 'cap2'
109  *
110  * (default: ~5%)
111  */
112 #define capacity_greater(cap1, cap2) ((cap1) * 1024 > (cap2) * 1078)
113 
114 #ifdef CONFIG_CFS_BANDWIDTH
115 /*
116  * Amount of runtime to allocate from global (tg) to local (per-cfs_rq) pool
117  * each time a cfs_rq requests quota.
118  *
119  * Note: in the case that the slice exceeds the runtime remaining (either due
120  * to consumption or the quota being specified to be smaller than the slice)
121  * we will always only issue the remaining available time.
122  *
123  * (default: 5 msec, units: microseconds)
124  */
125 static unsigned int sysctl_sched_cfs_bandwidth_slice		= 5000UL;
126 #endif
127 
128 #ifdef CONFIG_NUMA_BALANCING
129 /* Restrict the NUMA promotion throughput (MB/s) for each target node. */
130 static unsigned int sysctl_numa_balancing_promote_rate_limit = 65536;
131 #endif
132 
133 #ifdef CONFIG_SYSCTL
134 static const struct ctl_table sched_fair_sysctls[] = {
135 #ifdef CONFIG_CFS_BANDWIDTH
136 	{
137 		.procname       = "sched_cfs_bandwidth_slice_us",
138 		.data           = &sysctl_sched_cfs_bandwidth_slice,
139 		.maxlen         = sizeof(unsigned int),
140 		.mode           = 0644,
141 		.proc_handler   = proc_dointvec_minmax,
142 		.extra1         = SYSCTL_ONE,
143 	},
144 #endif
145 #ifdef CONFIG_NUMA_BALANCING
146 	{
147 		.procname	= "numa_balancing_promote_rate_limit_MBps",
148 		.data		= &sysctl_numa_balancing_promote_rate_limit,
149 		.maxlen		= sizeof(unsigned int),
150 		.mode		= 0644,
151 		.proc_handler	= proc_dointvec_minmax,
152 		.extra1		= SYSCTL_ZERO,
153 	},
154 #endif /* CONFIG_NUMA_BALANCING */
155 };
156 
157 static int __init sched_fair_sysctl_init(void)
158 {
159 	register_sysctl_init("kernel", sched_fair_sysctls);
160 	return 0;
161 }
162 late_initcall(sched_fair_sysctl_init);
163 #endif /* CONFIG_SYSCTL */
164 
165 static inline void update_load_add(struct load_weight *lw, unsigned long inc)
166 {
167 	lw->weight += inc;
168 	lw->inv_weight = 0;
169 }
170 
171 static inline void update_load_sub(struct load_weight *lw, unsigned long dec)
172 {
173 	lw->weight -= dec;
174 	lw->inv_weight = 0;
175 }
176 
177 static inline void update_load_set(struct load_weight *lw, unsigned long w)
178 {
179 	lw->weight = w;
180 	lw->inv_weight = 0;
181 }
182 
183 /*
184  * Increase the granularity value when there are more CPUs,
185  * because with more CPUs the 'effective latency' as visible
186  * to users decreases. But the relationship is not linear,
187  * so pick a second-best guess by going with the log2 of the
188  * number of CPUs.
189  *
190  * This idea comes from the SD scheduler of Con Kolivas:
191  */
192 static unsigned int get_update_sysctl_factor(void)
193 {
194 	unsigned int cpus = min_t(unsigned int, num_online_cpus(), 8);
195 	unsigned int factor;
196 
197 	switch (sysctl_sched_tunable_scaling) {
198 	case SCHED_TUNABLESCALING_NONE:
199 		factor = 1;
200 		break;
201 	case SCHED_TUNABLESCALING_LINEAR:
202 		factor = cpus;
203 		break;
204 	case SCHED_TUNABLESCALING_LOG:
205 	default:
206 		factor = 1 + ilog2(cpus);
207 		break;
208 	}
209 
210 	return factor;
211 }
212 
213 static void update_sysctl(void)
214 {
215 	unsigned int factor = get_update_sysctl_factor();
216 
217 #define SET_SYSCTL(name) \
218 	(sysctl_##name = (factor) * normalized_sysctl_##name)
219 	SET_SYSCTL(sched_base_slice);
220 #undef SET_SYSCTL
221 }
222 
223 void __init sched_init_granularity(void)
224 {
225 	update_sysctl();
226 }
227 
228 #define WMULT_CONST	(~0U)
229 #define WMULT_SHIFT	32
230 
231 static void __update_inv_weight(struct load_weight *lw)
232 {
233 	unsigned long w;
234 
235 	if (likely(lw->inv_weight))
236 		return;
237 
238 	w = scale_load_down(lw->weight);
239 
240 	if (BITS_PER_LONG > 32 && unlikely(w >= WMULT_CONST))
241 		lw->inv_weight = 1;
242 	else if (unlikely(!w))
243 		lw->inv_weight = WMULT_CONST;
244 	else
245 		lw->inv_weight = WMULT_CONST / w;
246 }
247 
248 /*
249  * delta_exec * weight / lw.weight
250  *   OR
251  * (delta_exec * (weight * lw->inv_weight)) >> WMULT_SHIFT
252  *
253  * Either weight := NICE_0_LOAD and lw \e sched_prio_to_wmult[], in which case
254  * we're guaranteed shift stays positive because inv_weight is guaranteed to
255  * fit 32 bits, and NICE_0_LOAD gives another 10 bits; therefore shift >= 22.
256  *
257  * Or, weight =< lw.weight (because lw.weight is the runqueue weight), thus
258  * weight/lw.weight <= 1, and therefore our shift will also be positive.
259  */
260 static u64 __calc_delta(u64 delta_exec, unsigned long weight, struct load_weight *lw)
261 {
262 	u64 fact = scale_load_down(weight);
263 	u32 fact_hi = (u32)(fact >> 32);
264 	int shift = WMULT_SHIFT;
265 	int fs;
266 
267 	__update_inv_weight(lw);
268 
269 	if (unlikely(fact_hi)) {
270 		fs = fls(fact_hi);
271 		shift -= fs;
272 		fact >>= fs;
273 	}
274 
275 	fact = mul_u32_u32(fact, lw->inv_weight);
276 
277 	fact_hi = (u32)(fact >> 32);
278 	if (fact_hi) {
279 		fs = fls(fact_hi);
280 		shift -= fs;
281 		fact >>= fs;
282 	}
283 
284 	return mul_u64_u32_shr(delta_exec, fact, shift);
285 }
286 
287 /*
288  * delta /= w
289  */
290 static inline u64 calc_delta_fair(u64 delta, struct sched_entity *se)
291 {
292 	if (unlikely(se->load.weight != NICE_0_LOAD))
293 		delta = __calc_delta(delta, NICE_0_LOAD, &se->load);
294 
295 	return delta;
296 }
297 
298 const struct sched_class fair_sched_class;
299 
300 /**************************************************************
301  * CFS operations on generic schedulable entities:
302  */
303 
304 #ifdef CONFIG_FAIR_GROUP_SCHED
305 
306 /* Walk up scheduling entities hierarchy */
307 #define for_each_sched_entity(se) \
308 		for (; se; se = se->parent)
309 
310 static inline bool list_add_leaf_cfs_rq(struct cfs_rq *cfs_rq)
311 {
312 	struct rq *rq = rq_of(cfs_rq);
313 	int cpu = cpu_of(rq);
314 
315 	if (cfs_rq->on_list)
316 		return rq->tmp_alone_branch == &rq->leaf_cfs_rq_list;
317 
318 	cfs_rq->on_list = 1;
319 
320 	/*
321 	 * Ensure we either appear before our parent (if already
322 	 * enqueued) or force our parent to appear after us when it is
323 	 * enqueued. The fact that we always enqueue bottom-up
324 	 * reduces this to two cases and a special case for the root
325 	 * cfs_rq. Furthermore, it also means that we will always reset
326 	 * tmp_alone_branch either when the branch is connected
327 	 * to a tree or when we reach the top of the tree
328 	 */
329 	if (cfs_rq->tg->parent &&
330 	    cfs_rq->tg->parent->cfs_rq[cpu]->on_list) {
331 		/*
332 		 * If parent is already on the list, we add the child
333 		 * just before. Thanks to circular linked property of
334 		 * the list, this means to put the child at the tail
335 		 * of the list that starts by parent.
336 		 */
337 		list_add_tail_rcu(&cfs_rq->leaf_cfs_rq_list,
338 			&(cfs_rq->tg->parent->cfs_rq[cpu]->leaf_cfs_rq_list));
339 		/*
340 		 * The branch is now connected to its tree so we can
341 		 * reset tmp_alone_branch to the beginning of the
342 		 * list.
343 		 */
344 		rq->tmp_alone_branch = &rq->leaf_cfs_rq_list;
345 		return true;
346 	}
347 
348 	if (!cfs_rq->tg->parent) {
349 		/*
350 		 * cfs rq without parent should be put
351 		 * at the tail of the list.
352 		 */
353 		list_add_tail_rcu(&cfs_rq->leaf_cfs_rq_list,
354 			&rq->leaf_cfs_rq_list);
355 		/*
356 		 * We have reach the top of a tree so we can reset
357 		 * tmp_alone_branch to the beginning of the list.
358 		 */
359 		rq->tmp_alone_branch = &rq->leaf_cfs_rq_list;
360 		return true;
361 	}
362 
363 	/*
364 	 * The parent has not already been added so we want to
365 	 * make sure that it will be put after us.
366 	 * tmp_alone_branch points to the begin of the branch
367 	 * where we will add parent.
368 	 */
369 	list_add_rcu(&cfs_rq->leaf_cfs_rq_list, rq->tmp_alone_branch);
370 	/*
371 	 * update tmp_alone_branch to points to the new begin
372 	 * of the branch
373 	 */
374 	rq->tmp_alone_branch = &cfs_rq->leaf_cfs_rq_list;
375 	return false;
376 }
377 
378 static inline void list_del_leaf_cfs_rq(struct cfs_rq *cfs_rq)
379 {
380 	if (cfs_rq->on_list) {
381 		struct rq *rq = rq_of(cfs_rq);
382 
383 		/*
384 		 * With cfs_rq being unthrottled/throttled during an enqueue,
385 		 * it can happen the tmp_alone_branch points to the leaf that
386 		 * we finally want to delete. In this case, tmp_alone_branch moves
387 		 * to the prev element but it will point to rq->leaf_cfs_rq_list
388 		 * at the end of the enqueue.
389 		 */
390 		if (rq->tmp_alone_branch == &cfs_rq->leaf_cfs_rq_list)
391 			rq->tmp_alone_branch = cfs_rq->leaf_cfs_rq_list.prev;
392 
393 		list_del_rcu(&cfs_rq->leaf_cfs_rq_list);
394 		cfs_rq->on_list = 0;
395 	}
396 }
397 
398 static inline void assert_list_leaf_cfs_rq(struct rq *rq)
399 {
400 	WARN_ON_ONCE(rq->tmp_alone_branch != &rq->leaf_cfs_rq_list);
401 }
402 
403 /* Iterate through all leaf cfs_rq's on a runqueue */
404 #define for_each_leaf_cfs_rq_safe(rq, cfs_rq, pos)			\
405 	list_for_each_entry_safe(cfs_rq, pos, &rq->leaf_cfs_rq_list,	\
406 				 leaf_cfs_rq_list)
407 
408 /* Do the two (enqueued) entities belong to the same group ? */
409 static inline struct cfs_rq *
410 is_same_group(struct sched_entity *se, struct sched_entity *pse)
411 {
412 	if (se->cfs_rq == pse->cfs_rq)
413 		return se->cfs_rq;
414 
415 	return NULL;
416 }
417 
418 static inline struct sched_entity *parent_entity(const struct sched_entity *se)
419 {
420 	return se->parent;
421 }
422 
423 static void
424 find_matching_se(struct sched_entity **se, struct sched_entity **pse)
425 {
426 	int se_depth, pse_depth;
427 
428 	/*
429 	 * preemption test can be made between sibling entities who are in the
430 	 * same cfs_rq i.e who have a common parent. Walk up the hierarchy of
431 	 * both tasks until we find their ancestors who are siblings of common
432 	 * parent.
433 	 */
434 
435 	/* First walk up until both entities are at same depth */
436 	se_depth = (*se)->depth;
437 	pse_depth = (*pse)->depth;
438 
439 	while (se_depth > pse_depth) {
440 		se_depth--;
441 		*se = parent_entity(*se);
442 	}
443 
444 	while (pse_depth > se_depth) {
445 		pse_depth--;
446 		*pse = parent_entity(*pse);
447 	}
448 
449 	while (!is_same_group(*se, *pse)) {
450 		*se = parent_entity(*se);
451 		*pse = parent_entity(*pse);
452 	}
453 }
454 
455 static int tg_is_idle(struct task_group *tg)
456 {
457 	return tg->idle > 0;
458 }
459 
460 static int cfs_rq_is_idle(struct cfs_rq *cfs_rq)
461 {
462 	return cfs_rq->idle > 0;
463 }
464 
465 static int se_is_idle(struct sched_entity *se)
466 {
467 	if (entity_is_task(se))
468 		return task_has_idle_policy(task_of(se));
469 	return cfs_rq_is_idle(group_cfs_rq(se));
470 }
471 
472 #else /* !CONFIG_FAIR_GROUP_SCHED: */
473 
474 #define for_each_sched_entity(se) \
475 		for (; se; se = NULL)
476 
477 static inline bool list_add_leaf_cfs_rq(struct cfs_rq *cfs_rq)
478 {
479 	return true;
480 }
481 
482 static inline void list_del_leaf_cfs_rq(struct cfs_rq *cfs_rq)
483 {
484 }
485 
486 static inline void assert_list_leaf_cfs_rq(struct rq *rq)
487 {
488 }
489 
490 #define for_each_leaf_cfs_rq_safe(rq, cfs_rq, pos)	\
491 		for (cfs_rq = &rq->cfs, pos = NULL; cfs_rq; cfs_rq = pos)
492 
493 static inline struct sched_entity *parent_entity(struct sched_entity *se)
494 {
495 	return NULL;
496 }
497 
498 static inline void
499 find_matching_se(struct sched_entity **se, struct sched_entity **pse)
500 {
501 }
502 
503 static inline int tg_is_idle(struct task_group *tg)
504 {
505 	return 0;
506 }
507 
508 static int cfs_rq_is_idle(struct cfs_rq *cfs_rq)
509 {
510 	return 0;
511 }
512 
513 static int se_is_idle(struct sched_entity *se)
514 {
515 	return task_has_idle_policy(task_of(se));
516 }
517 
518 #endif /* !CONFIG_FAIR_GROUP_SCHED */
519 
520 static __always_inline
521 void account_cfs_rq_runtime(struct cfs_rq *cfs_rq, u64 delta_exec);
522 
523 /**************************************************************
524  * Scheduling class tree data structure manipulation methods:
525  */
526 
527 extern void __BUILD_BUG_vruntime_cmp(void);
528 
529 /* Use __builtin_strcmp() because of __HAVE_ARCH_STRCMP: */
530 
531 #define vruntime_cmp(A, CMP_STR, B) ({				\
532 	int __res = 0;						\
533 								\
534 	if (!__builtin_strcmp(CMP_STR, "<")) {			\
535 		__res = ((s64)((A)-(B)) < 0);			\
536 	} else if (!__builtin_strcmp(CMP_STR, "<=")) {		\
537 		__res = ((s64)((A)-(B)) <= 0);			\
538 	} else if (!__builtin_strcmp(CMP_STR, ">")) {		\
539 		__res = ((s64)((A)-(B)) > 0);			\
540 	} else if (!__builtin_strcmp(CMP_STR, ">=")) {		\
541 		__res = ((s64)((A)-(B)) >= 0);			\
542 	} else {						\
543 		/* Unknown operator throws linker error: */	\
544 		__BUILD_BUG_vruntime_cmp();			\
545 	}							\
546 								\
547 	__res;							\
548 })
549 
550 extern void __BUILD_BUG_vruntime_op(void);
551 
552 #define vruntime_op(A, OP_STR, B) ({				\
553 	s64 __res = 0;						\
554 								\
555 	if (!__builtin_strcmp(OP_STR, "-")) {			\
556 		__res = (s64)((A)-(B));				\
557 	} else {						\
558 		/* Unknown operator throws linker error: */	\
559 		__BUILD_BUG_vruntime_op();			\
560 	}							\
561 								\
562 	__res;						\
563 })
564 
565 
566 static inline __maybe_unused u64 max_vruntime(u64 max_vruntime, u64 vruntime)
567 {
568 	if (vruntime_cmp(vruntime, ">", max_vruntime))
569 		max_vruntime = vruntime;
570 
571 	return max_vruntime;
572 }
573 
574 static inline __maybe_unused u64 min_vruntime(u64 min_vruntime, u64 vruntime)
575 {
576 	if (vruntime_cmp(vruntime, "<", min_vruntime))
577 		min_vruntime = vruntime;
578 
579 	return min_vruntime;
580 }
581 
582 static inline bool entity_before(const struct sched_entity *a,
583 				 const struct sched_entity *b)
584 {
585 	/*
586 	 * Tiebreak on vruntime seems unnecessary since it can
587 	 * hardly happen.
588 	 */
589 	return vruntime_cmp(a->deadline, "<", b->deadline);
590 }
591 
592 static inline s64 entity_key(struct cfs_rq *cfs_rq, struct sched_entity *se)
593 {
594 	return vruntime_op(se->vruntime, "-", cfs_rq->zero_vruntime);
595 }
596 
597 #define __node_2_se(node) \
598 	rb_entry((node), struct sched_entity, run_node)
599 
600 /*
601  * Compute virtual time from the per-task service numbers:
602  *
603  * Fair schedulers conserve lag:
604  *
605  *   \Sum lag_i = 0
606  *
607  * Where lag_i is given by:
608  *
609  *   lag_i = S - s_i = w_i * (V - v_i)
610  *
611  * Where S is the ideal service time and V is it's virtual time counterpart.
612  * Therefore:
613  *
614  *   \Sum lag_i = 0
615  *   \Sum w_i * (V - v_i) = 0
616  *   \Sum (w_i * V - w_i * v_i) = 0
617  *
618  * From which we can solve an expression for V in v_i (which we have in
619  * se->vruntime):
620  *
621  *       \Sum v_i * w_i   \Sum v_i * w_i
622  *   V = -------------- = --------------
623  *          \Sum w_i            W
624  *
625  * Specifically, this is the weighted average of all entity virtual runtimes.
626  *
627  * [[ NOTE: this is only equal to the ideal scheduler under the condition
628  *          that join/leave operations happen at lag_i = 0, otherwise the
629  *          virtual time has non-contiguous motion equivalent to:
630  *
631  *	      V +-= lag_i / W
632  *
633  *	    Also see the comment in place_entity() that deals with this. ]]
634  *
635  * However, since v_i is u64, and the multiplication could easily overflow
636  * transform it into a relative form that uses smaller quantities:
637  *
638  * Substitute: v_i == (v_i - v0) + v0
639  *
640  *     \Sum ((v_i - v0) + v0) * w_i   \Sum (v_i - v0) * w_i
641  * V = ---------------------------- = --------------------- + v0
642  *                  W                            W
643  *
644  * Which we track using:
645  *
646  *                    v0 := cfs_rq->zero_vruntime
647  * \Sum (v_i - v0) * w_i := cfs_rq->sum_w_vruntime
648  *              \Sum w_i := cfs_rq->sum_weight
649  *
650  * Since zero_vruntime closely tracks the per-task service, these
651  * deltas: (v_i - v0), will be in the order of the maximal (virtual) lag
652  * induced in the system due to quantisation.
653  *
654  * Also, we use scale_load_down() to reduce the size.
655  *
656  * As measured, the max (key * weight) value was ~44 bits for a kernel build.
657  */
658 static void
659 sum_w_vruntime_add(struct cfs_rq *cfs_rq, struct sched_entity *se)
660 {
661 	unsigned long weight = scale_load_down(se->load.weight);
662 	s64 key = entity_key(cfs_rq, se);
663 
664 	cfs_rq->sum_w_vruntime += key * weight;
665 	cfs_rq->sum_weight += weight;
666 }
667 
668 static void
669 sum_w_vruntime_sub(struct cfs_rq *cfs_rq, struct sched_entity *se)
670 {
671 	unsigned long weight = scale_load_down(se->load.weight);
672 	s64 key = entity_key(cfs_rq, se);
673 
674 	cfs_rq->sum_w_vruntime -= key * weight;
675 	cfs_rq->sum_weight -= weight;
676 }
677 
678 static inline
679 void sum_w_vruntime_update(struct cfs_rq *cfs_rq, s64 delta)
680 {
681 	/*
682 	 * v' = v + d ==> sum_w_vruntime' = sum_runtime - d*sum_weight
683 	 */
684 	cfs_rq->sum_w_vruntime -= cfs_rq->sum_weight * delta;
685 }
686 
687 /*
688  * Specifically: avg_runtime() + 0 must result in entity_eligible() := true
689  * For this to be so, the result of this function must have a left bias.
690  */
691 u64 avg_vruntime(struct cfs_rq *cfs_rq)
692 {
693 	struct sched_entity *curr = cfs_rq->curr;
694 	s64 avg = cfs_rq->sum_w_vruntime;
695 	long load = cfs_rq->sum_weight;
696 
697 	if (curr && curr->on_rq) {
698 		unsigned long weight = scale_load_down(curr->load.weight);
699 
700 		avg += entity_key(cfs_rq, curr) * weight;
701 		load += weight;
702 	}
703 
704 	if (load) {
705 		/* sign flips effective floor / ceiling */
706 		if (avg < 0)
707 			avg -= (load - 1);
708 		avg = div_s64(avg, load);
709 	}
710 
711 	return cfs_rq->zero_vruntime + avg;
712 }
713 
714 /*
715  * lag_i = S - s_i = w_i * (V - v_i)
716  *
717  * However, since V is approximated by the weighted average of all entities it
718  * is possible -- by addition/removal/reweight to the tree -- to move V around
719  * and end up with a larger lag than we started with.
720  *
721  * Limit this to either double the slice length with a minimum of TICK_NSEC
722  * since that is the timing granularity.
723  *
724  * EEVDF gives the following limit for a steady state system:
725  *
726  *   -r_max < lag < max(r_max, q)
727  *
728  * XXX could add max_slice to the augmented data to track this.
729  */
730 static void update_entity_lag(struct cfs_rq *cfs_rq, struct sched_entity *se)
731 {
732 	s64 vlag, limit;
733 
734 	WARN_ON_ONCE(!se->on_rq);
735 
736 	vlag = avg_vruntime(cfs_rq) - se->vruntime;
737 	limit = calc_delta_fair(max_t(u64, 2*se->slice, TICK_NSEC), se);
738 
739 	se->vlag = clamp(vlag, -limit, limit);
740 }
741 
742 /*
743  * Entity is eligible once it received less service than it ought to have,
744  * eg. lag >= 0.
745  *
746  * lag_i = S - s_i = w_i*(V - v_i)
747  *
748  * lag_i >= 0 -> V >= v_i
749  *
750  *     \Sum (v_i - v)*w_i
751  * V = ------------------ + v
752  *          \Sum w_i
753  *
754  * lag_i >= 0 -> \Sum (v_i - v)*w_i >= (v_i - v)*(\Sum w_i)
755  *
756  * Note: using 'avg_vruntime() > se->vruntime' is inaccurate due
757  *       to the loss in precision caused by the division.
758  */
759 static int vruntime_eligible(struct cfs_rq *cfs_rq, u64 vruntime)
760 {
761 	struct sched_entity *curr = cfs_rq->curr;
762 	s64 avg = cfs_rq->sum_w_vruntime;
763 	long load = cfs_rq->sum_weight;
764 
765 	if (curr && curr->on_rq) {
766 		unsigned long weight = scale_load_down(curr->load.weight);
767 
768 		avg += entity_key(cfs_rq, curr) * weight;
769 		load += weight;
770 	}
771 
772 	return avg >= vruntime_op(vruntime, "-", cfs_rq->zero_vruntime) * load;
773 }
774 
775 int entity_eligible(struct cfs_rq *cfs_rq, struct sched_entity *se)
776 {
777 	return vruntime_eligible(cfs_rq, se->vruntime);
778 }
779 
780 static void update_zero_vruntime(struct cfs_rq *cfs_rq)
781 {
782 	u64 vruntime = avg_vruntime(cfs_rq);
783 	s64 delta = vruntime_op(vruntime, "-", cfs_rq->zero_vruntime);
784 
785 	sum_w_vruntime_update(cfs_rq, delta);
786 
787 	cfs_rq->zero_vruntime = vruntime;
788 }
789 
790 static inline u64 cfs_rq_min_slice(struct cfs_rq *cfs_rq)
791 {
792 	struct sched_entity *root = __pick_root_entity(cfs_rq);
793 	struct sched_entity *curr = cfs_rq->curr;
794 	u64 min_slice = ~0ULL;
795 
796 	if (curr && curr->on_rq)
797 		min_slice = curr->slice;
798 
799 	if (root)
800 		min_slice = min(min_slice, root->min_slice);
801 
802 	return min_slice;
803 }
804 
805 static inline bool __entity_less(struct rb_node *a, const struct rb_node *b)
806 {
807 	return entity_before(__node_2_se(a), __node_2_se(b));
808 }
809 
810 static inline void __min_vruntime_update(struct sched_entity *se, struct rb_node *node)
811 {
812 	if (node) {
813 		struct sched_entity *rse = __node_2_se(node);
814 
815 		if (vruntime_cmp(se->min_vruntime, ">", rse->min_vruntime))
816 			se->min_vruntime = rse->min_vruntime;
817 	}
818 }
819 
820 static inline void __min_slice_update(struct sched_entity *se, struct rb_node *node)
821 {
822 	if (node) {
823 		struct sched_entity *rse = __node_2_se(node);
824 		if (rse->min_slice < se->min_slice)
825 			se->min_slice = rse->min_slice;
826 	}
827 }
828 
829 /*
830  * se->min_vruntime = min(se->vruntime, {left,right}->min_vruntime)
831  */
832 static inline bool min_vruntime_update(struct sched_entity *se, bool exit)
833 {
834 	u64 old_min_vruntime = se->min_vruntime;
835 	u64 old_min_slice = se->min_slice;
836 	struct rb_node *node = &se->run_node;
837 
838 	se->min_vruntime = se->vruntime;
839 	__min_vruntime_update(se, node->rb_right);
840 	__min_vruntime_update(se, node->rb_left);
841 
842 	se->min_slice = se->slice;
843 	__min_slice_update(se, node->rb_right);
844 	__min_slice_update(se, node->rb_left);
845 
846 	return se->min_vruntime == old_min_vruntime &&
847 	       se->min_slice == old_min_slice;
848 }
849 
850 RB_DECLARE_CALLBACKS(static, min_vruntime_cb, struct sched_entity,
851 		     run_node, min_vruntime, min_vruntime_update);
852 
853 /*
854  * Enqueue an entity into the rb-tree:
855  */
856 static void __enqueue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se)
857 {
858 	sum_w_vruntime_add(cfs_rq, se);
859 	update_zero_vruntime(cfs_rq);
860 	se->min_vruntime = se->vruntime;
861 	se->min_slice = se->slice;
862 	rb_add_augmented_cached(&se->run_node, &cfs_rq->tasks_timeline,
863 				__entity_less, &min_vruntime_cb);
864 }
865 
866 static void __dequeue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se)
867 {
868 	rb_erase_augmented_cached(&se->run_node, &cfs_rq->tasks_timeline,
869 				  &min_vruntime_cb);
870 	sum_w_vruntime_sub(cfs_rq, se);
871 	update_zero_vruntime(cfs_rq);
872 }
873 
874 struct sched_entity *__pick_root_entity(struct cfs_rq *cfs_rq)
875 {
876 	struct rb_node *root = cfs_rq->tasks_timeline.rb_root.rb_node;
877 
878 	if (!root)
879 		return NULL;
880 
881 	return __node_2_se(root);
882 }
883 
884 struct sched_entity *__pick_first_entity(struct cfs_rq *cfs_rq)
885 {
886 	struct rb_node *left = rb_first_cached(&cfs_rq->tasks_timeline);
887 
888 	if (!left)
889 		return NULL;
890 
891 	return __node_2_se(left);
892 }
893 
894 /*
895  * Set the vruntime up to which an entity can run before looking
896  * for another entity to pick.
897  * In case of run to parity, we use the shortest slice of the enqueued
898  * entities to set the protected period.
899  * When run to parity is disabled, we give a minimum quantum to the running
900  * entity to ensure progress.
901  */
902 static inline void set_protect_slice(struct cfs_rq *cfs_rq, struct sched_entity *se)
903 {
904 	u64 slice = normalized_sysctl_sched_base_slice;
905 	u64 vprot = se->deadline;
906 
907 	if (sched_feat(RUN_TO_PARITY))
908 		slice = cfs_rq_min_slice(cfs_rq);
909 
910 	slice = min(slice, se->slice);
911 	if (slice != se->slice)
912 		vprot = min_vruntime(vprot, se->vruntime + calc_delta_fair(slice, se));
913 
914 	se->vprot = vprot;
915 }
916 
917 static inline void update_protect_slice(struct cfs_rq *cfs_rq, struct sched_entity *se)
918 {
919 	u64 slice = cfs_rq_min_slice(cfs_rq);
920 
921 	se->vprot = min_vruntime(se->vprot, se->vruntime + calc_delta_fair(slice, se));
922 }
923 
924 static inline bool protect_slice(struct sched_entity *se)
925 {
926 	return vruntime_cmp(se->vruntime, "<", se->vprot);
927 }
928 
929 static inline void cancel_protect_slice(struct sched_entity *se)
930 {
931 	if (protect_slice(se))
932 		se->vprot = se->vruntime;
933 }
934 
935 /*
936  * Earliest Eligible Virtual Deadline First
937  *
938  * In order to provide latency guarantees for different request sizes
939  * EEVDF selects the best runnable task from two criteria:
940  *
941  *  1) the task must be eligible (must be owed service)
942  *
943  *  2) from those tasks that meet 1), we select the one
944  *     with the earliest virtual deadline.
945  *
946  * We can do this in O(log n) time due to an augmented RB-tree. The
947  * tree keeps the entries sorted on deadline, but also functions as a
948  * heap based on the vruntime by keeping:
949  *
950  *  se->min_vruntime = min(se->vruntime, se->{left,right}->min_vruntime)
951  *
952  * Which allows tree pruning through eligibility.
953  */
954 static struct sched_entity *__pick_eevdf(struct cfs_rq *cfs_rq, bool protect)
955 {
956 	struct rb_node *node = cfs_rq->tasks_timeline.rb_root.rb_node;
957 	struct sched_entity *se = __pick_first_entity(cfs_rq);
958 	struct sched_entity *curr = cfs_rq->curr;
959 	struct sched_entity *best = NULL;
960 
961 	/*
962 	 * We can safely skip eligibility check if there is only one entity
963 	 * in this cfs_rq, saving some cycles.
964 	 */
965 	if (cfs_rq->nr_queued == 1)
966 		return curr && curr->on_rq ? curr : se;
967 
968 	/*
969 	 * Picking the ->next buddy will affect latency but not fairness.
970 	 */
971 	if (sched_feat(PICK_BUDDY) &&
972 	    cfs_rq->next && entity_eligible(cfs_rq, cfs_rq->next)) {
973 		/* ->next will never be delayed */
974 		WARN_ON_ONCE(cfs_rq->next->sched_delayed);
975 		return cfs_rq->next;
976 	}
977 
978 	if (curr && (!curr->on_rq || !entity_eligible(cfs_rq, curr)))
979 		curr = NULL;
980 
981 	if (curr && protect && protect_slice(curr))
982 		return curr;
983 
984 	/* Pick the leftmost entity if it's eligible */
985 	if (se && entity_eligible(cfs_rq, se)) {
986 		best = se;
987 		goto found;
988 	}
989 
990 	/* Heap search for the EEVD entity */
991 	while (node) {
992 		struct rb_node *left = node->rb_left;
993 
994 		/*
995 		 * Eligible entities in left subtree are always better
996 		 * choices, since they have earlier deadlines.
997 		 */
998 		if (left && vruntime_eligible(cfs_rq,
999 					__node_2_se(left)->min_vruntime)) {
1000 			node = left;
1001 			continue;
1002 		}
1003 
1004 		se = __node_2_se(node);
1005 
1006 		/*
1007 		 * The left subtree either is empty or has no eligible
1008 		 * entity, so check the current node since it is the one
1009 		 * with earliest deadline that might be eligible.
1010 		 */
1011 		if (entity_eligible(cfs_rq, se)) {
1012 			best = se;
1013 			break;
1014 		}
1015 
1016 		node = node->rb_right;
1017 	}
1018 found:
1019 	if (!best || (curr && entity_before(curr, best)))
1020 		best = curr;
1021 
1022 	return best;
1023 }
1024 
1025 static struct sched_entity *pick_eevdf(struct cfs_rq *cfs_rq)
1026 {
1027 	return __pick_eevdf(cfs_rq, true);
1028 }
1029 
1030 struct sched_entity *__pick_last_entity(struct cfs_rq *cfs_rq)
1031 {
1032 	struct rb_node *last = rb_last(&cfs_rq->tasks_timeline.rb_root);
1033 
1034 	if (!last)
1035 		return NULL;
1036 
1037 	return __node_2_se(last);
1038 }
1039 
1040 /**************************************************************
1041  * Scheduling class statistics methods:
1042  */
1043 int sched_update_scaling(void)
1044 {
1045 	unsigned int factor = get_update_sysctl_factor();
1046 
1047 #define WRT_SYSCTL(name) \
1048 	(normalized_sysctl_##name = sysctl_##name / (factor))
1049 	WRT_SYSCTL(sched_base_slice);
1050 #undef WRT_SYSCTL
1051 
1052 	return 0;
1053 }
1054 
1055 static void clear_buddies(struct cfs_rq *cfs_rq, struct sched_entity *se);
1056 
1057 /*
1058  * XXX: strictly: vd_i += N*r_i/w_i such that: vd_i > ve_i
1059  * this is probably good enough.
1060  */
1061 static bool update_deadline(struct cfs_rq *cfs_rq, struct sched_entity *se)
1062 {
1063 	if (vruntime_cmp(se->vruntime, "<", se->deadline))
1064 		return false;
1065 
1066 	/*
1067 	 * For EEVDF the virtual time slope is determined by w_i (iow.
1068 	 * nice) while the request time r_i is determined by
1069 	 * sysctl_sched_base_slice.
1070 	 */
1071 	if (!se->custom_slice)
1072 		se->slice = sysctl_sched_base_slice;
1073 
1074 	/*
1075 	 * EEVDF: vd_i = ve_i + r_i / w_i
1076 	 */
1077 	se->deadline = se->vruntime + calc_delta_fair(se->slice, se);
1078 
1079 	/*
1080 	 * The task has consumed its request, reschedule.
1081 	 */
1082 	return true;
1083 }
1084 
1085 #include "pelt.h"
1086 
1087 static int select_idle_sibling(struct task_struct *p, int prev_cpu, int cpu);
1088 static unsigned long task_h_load(struct task_struct *p);
1089 static unsigned long capacity_of(int cpu);
1090 
1091 /* Give new sched_entity start runnable values to heavy its load in infant time */
1092 void init_entity_runnable_average(struct sched_entity *se)
1093 {
1094 	struct sched_avg *sa = &se->avg;
1095 
1096 	memset(sa, 0, sizeof(*sa));
1097 
1098 	/*
1099 	 * Tasks are initialized with full load to be seen as heavy tasks until
1100 	 * they get a chance to stabilize to their real load level.
1101 	 * Group entities are initialized with zero load to reflect the fact that
1102 	 * nothing has been attached to the task group yet.
1103 	 */
1104 	if (entity_is_task(se))
1105 		sa->load_avg = scale_load_down(se->load.weight);
1106 
1107 	/* when this task is enqueued, it will contribute to its cfs_rq's load_avg */
1108 }
1109 
1110 /*
1111  * With new tasks being created, their initial util_avgs are extrapolated
1112  * based on the cfs_rq's current util_avg:
1113  *
1114  *   util_avg = cfs_rq->avg.util_avg / (cfs_rq->avg.load_avg + 1)
1115  *		* se_weight(se)
1116  *
1117  * However, in many cases, the above util_avg does not give a desired
1118  * value. Moreover, the sum of the util_avgs may be divergent, such
1119  * as when the series is a harmonic series.
1120  *
1121  * To solve this problem, we also cap the util_avg of successive tasks to
1122  * only 1/2 of the left utilization budget:
1123  *
1124  *   util_avg_cap = (cpu_scale - cfs_rq->avg.util_avg) / 2^n
1125  *
1126  * where n denotes the nth task and cpu_scale the CPU capacity.
1127  *
1128  * For example, for a CPU with 1024 of capacity, a simplest series from
1129  * the beginning would be like:
1130  *
1131  *  task  util_avg: 512, 256, 128,  64,  32,   16,    8, ...
1132  * cfs_rq util_avg: 512, 768, 896, 960, 992, 1008, 1016, ...
1133  *
1134  * Finally, that extrapolated util_avg is clamped to the cap (util_avg_cap)
1135  * if util_avg > util_avg_cap.
1136  */
1137 void post_init_entity_util_avg(struct task_struct *p)
1138 {
1139 	struct sched_entity *se = &p->se;
1140 	struct cfs_rq *cfs_rq = cfs_rq_of(se);
1141 	struct sched_avg *sa = &se->avg;
1142 	long cpu_scale = arch_scale_cpu_capacity(cpu_of(rq_of(cfs_rq)));
1143 	long cap = (long)(cpu_scale - cfs_rq->avg.util_avg) / 2;
1144 
1145 	if (p->sched_class != &fair_sched_class) {
1146 		/*
1147 		 * For !fair tasks do:
1148 		 *
1149 		update_cfs_rq_load_avg(now, cfs_rq);
1150 		attach_entity_load_avg(cfs_rq, se);
1151 		switched_from_fair(rq, p);
1152 		 *
1153 		 * such that the next switched_to_fair() has the
1154 		 * expected state.
1155 		 */
1156 		se->avg.last_update_time = cfs_rq_clock_pelt(cfs_rq);
1157 		return;
1158 	}
1159 
1160 	if (cap > 0) {
1161 		if (cfs_rq->avg.util_avg != 0) {
1162 			sa->util_avg  = cfs_rq->avg.util_avg * se_weight(se);
1163 			sa->util_avg /= (cfs_rq->avg.load_avg + 1);
1164 
1165 			if (sa->util_avg > cap)
1166 				sa->util_avg = cap;
1167 		} else {
1168 			sa->util_avg = cap;
1169 		}
1170 	}
1171 
1172 	sa->runnable_avg = sa->util_avg;
1173 }
1174 
1175 static s64 update_se(struct rq *rq, struct sched_entity *se)
1176 {
1177 	u64 now = rq_clock_task(rq);
1178 	s64 delta_exec;
1179 
1180 	delta_exec = now - se->exec_start;
1181 	if (unlikely(delta_exec <= 0))
1182 		return delta_exec;
1183 
1184 	se->exec_start = now;
1185 	if (entity_is_task(se)) {
1186 		struct task_struct *donor = task_of(se);
1187 		struct task_struct *running = rq->curr;
1188 		/*
1189 		 * If se is a task, we account the time against the running
1190 		 * task, as w/ proxy-exec they may not be the same.
1191 		 */
1192 		running->se.exec_start = now;
1193 		running->se.sum_exec_runtime += delta_exec;
1194 
1195 		trace_sched_stat_runtime(running, delta_exec);
1196 		account_group_exec_runtime(running, delta_exec);
1197 
1198 		/* cgroup time is always accounted against the donor */
1199 		cgroup_account_cputime(donor, delta_exec);
1200 	} else {
1201 		/* If not task, account the time against donor se  */
1202 		se->sum_exec_runtime += delta_exec;
1203 	}
1204 
1205 	if (schedstat_enabled()) {
1206 		struct sched_statistics *stats;
1207 
1208 		stats = __schedstats_from_se(se);
1209 		__schedstat_set(stats->exec_max,
1210 				max(delta_exec, stats->exec_max));
1211 	}
1212 
1213 	return delta_exec;
1214 }
1215 
1216 static void set_next_buddy(struct sched_entity *se);
1217 
1218 /*
1219  * Used by other classes to account runtime.
1220  */
1221 s64 update_curr_common(struct rq *rq)
1222 {
1223 	return update_se(rq, &rq->donor->se);
1224 }
1225 
1226 /*
1227  * Update the current task's runtime statistics.
1228  */
1229 static void update_curr(struct cfs_rq *cfs_rq)
1230 {
1231 	/*
1232 	 * Note: cfs_rq->curr corresponds to the task picked to
1233 	 * run (ie: rq->donor.se) which due to proxy-exec may
1234 	 * not necessarily be the actual task running
1235 	 * (rq->curr.se). This is easy to confuse!
1236 	 */
1237 	struct sched_entity *curr = cfs_rq->curr;
1238 	struct rq *rq = rq_of(cfs_rq);
1239 	s64 delta_exec;
1240 	bool resched;
1241 
1242 	if (unlikely(!curr))
1243 		return;
1244 
1245 	delta_exec = update_se(rq, curr);
1246 	if (unlikely(delta_exec <= 0))
1247 		return;
1248 
1249 	curr->vruntime += calc_delta_fair(delta_exec, curr);
1250 	resched = update_deadline(cfs_rq, curr);
1251 
1252 	if (entity_is_task(curr)) {
1253 		/*
1254 		 * If the fair_server is active, we need to account for the
1255 		 * fair_server time whether or not the task is running on
1256 		 * behalf of fair_server or not:
1257 		 *  - If the task is running on behalf of fair_server, we need
1258 		 *    to limit its time based on the assigned runtime.
1259 		 *  - Fair task that runs outside of fair_server should account
1260 		 *    against fair_server such that it can account for this time
1261 		 *    and possibly avoid running this period.
1262 		 */
1263 		dl_server_update(&rq->fair_server, delta_exec);
1264 	}
1265 
1266 	account_cfs_rq_runtime(cfs_rq, delta_exec);
1267 
1268 	if (cfs_rq->nr_queued == 1)
1269 		return;
1270 
1271 	if (resched || !protect_slice(curr)) {
1272 		resched_curr_lazy(rq);
1273 		clear_buddies(cfs_rq, curr);
1274 	}
1275 }
1276 
1277 static void update_curr_fair(struct rq *rq)
1278 {
1279 	update_curr(cfs_rq_of(&rq->donor->se));
1280 }
1281 
1282 static inline void
1283 update_stats_wait_start_fair(struct cfs_rq *cfs_rq, struct sched_entity *se)
1284 {
1285 	struct sched_statistics *stats;
1286 	struct task_struct *p = NULL;
1287 
1288 	if (!schedstat_enabled())
1289 		return;
1290 
1291 	stats = __schedstats_from_se(se);
1292 
1293 	if (entity_is_task(se))
1294 		p = task_of(se);
1295 
1296 	__update_stats_wait_start(rq_of(cfs_rq), p, stats);
1297 }
1298 
1299 static inline void
1300 update_stats_wait_end_fair(struct cfs_rq *cfs_rq, struct sched_entity *se)
1301 {
1302 	struct sched_statistics *stats;
1303 	struct task_struct *p = NULL;
1304 
1305 	if (!schedstat_enabled())
1306 		return;
1307 
1308 	stats = __schedstats_from_se(se);
1309 
1310 	/*
1311 	 * When the sched_schedstat changes from 0 to 1, some sched se
1312 	 * maybe already in the runqueue, the se->statistics.wait_start
1313 	 * will be 0.So it will let the delta wrong. We need to avoid this
1314 	 * scenario.
1315 	 */
1316 	if (unlikely(!schedstat_val(stats->wait_start)))
1317 		return;
1318 
1319 	if (entity_is_task(se))
1320 		p = task_of(se);
1321 
1322 	__update_stats_wait_end(rq_of(cfs_rq), p, stats);
1323 }
1324 
1325 static inline void
1326 update_stats_enqueue_sleeper_fair(struct cfs_rq *cfs_rq, struct sched_entity *se)
1327 {
1328 	struct sched_statistics *stats;
1329 	struct task_struct *tsk = NULL;
1330 
1331 	if (!schedstat_enabled())
1332 		return;
1333 
1334 	stats = __schedstats_from_se(se);
1335 
1336 	if (entity_is_task(se))
1337 		tsk = task_of(se);
1338 
1339 	__update_stats_enqueue_sleeper(rq_of(cfs_rq), tsk, stats);
1340 }
1341 
1342 /*
1343  * Task is being enqueued - update stats:
1344  */
1345 static inline void
1346 update_stats_enqueue_fair(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags)
1347 {
1348 	if (!schedstat_enabled())
1349 		return;
1350 
1351 	/*
1352 	 * Are we enqueueing a waiting task? (for current tasks
1353 	 * a dequeue/enqueue event is a NOP)
1354 	 */
1355 	if (se != cfs_rq->curr)
1356 		update_stats_wait_start_fair(cfs_rq, se);
1357 
1358 	if (flags & ENQUEUE_WAKEUP)
1359 		update_stats_enqueue_sleeper_fair(cfs_rq, se);
1360 }
1361 
1362 static inline void
1363 update_stats_dequeue_fair(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags)
1364 {
1365 
1366 	if (!schedstat_enabled())
1367 		return;
1368 
1369 	/*
1370 	 * Mark the end of the wait period if dequeueing a
1371 	 * waiting task:
1372 	 */
1373 	if (se != cfs_rq->curr)
1374 		update_stats_wait_end_fair(cfs_rq, se);
1375 
1376 	if ((flags & DEQUEUE_SLEEP) && entity_is_task(se)) {
1377 		struct task_struct *tsk = task_of(se);
1378 		unsigned int state;
1379 
1380 		/* XXX racy against TTWU */
1381 		state = READ_ONCE(tsk->__state);
1382 		if (state & TASK_INTERRUPTIBLE)
1383 			__schedstat_set(tsk->stats.sleep_start,
1384 				      rq_clock(rq_of(cfs_rq)));
1385 		if (state & TASK_UNINTERRUPTIBLE)
1386 			__schedstat_set(tsk->stats.block_start,
1387 				      rq_clock(rq_of(cfs_rq)));
1388 	}
1389 }
1390 
1391 /*
1392  * We are picking a new current task - update its stats:
1393  */
1394 static inline void
1395 update_stats_curr_start(struct cfs_rq *cfs_rq, struct sched_entity *se)
1396 {
1397 	/*
1398 	 * We are starting a new run period:
1399 	 */
1400 	se->exec_start = rq_clock_task(rq_of(cfs_rq));
1401 }
1402 
1403 /**************************************************
1404  * Scheduling class queueing methods:
1405  */
1406 
1407 static inline bool is_core_idle(int cpu)
1408 {
1409 #ifdef CONFIG_SCHED_SMT
1410 	int sibling;
1411 
1412 	for_each_cpu(sibling, cpu_smt_mask(cpu)) {
1413 		if (cpu == sibling)
1414 			continue;
1415 
1416 		if (!idle_cpu(sibling))
1417 			return false;
1418 	}
1419 #endif
1420 
1421 	return true;
1422 }
1423 
1424 #ifdef CONFIG_NUMA
1425 #define NUMA_IMBALANCE_MIN 2
1426 
1427 static inline long
1428 adjust_numa_imbalance(int imbalance, int dst_running, int imb_numa_nr)
1429 {
1430 	/*
1431 	 * Allow a NUMA imbalance if busy CPUs is less than the maximum
1432 	 * threshold. Above this threshold, individual tasks may be contending
1433 	 * for both memory bandwidth and any shared HT resources.  This is an
1434 	 * approximation as the number of running tasks may not be related to
1435 	 * the number of busy CPUs due to sched_setaffinity.
1436 	 */
1437 	if (dst_running > imb_numa_nr)
1438 		return imbalance;
1439 
1440 	/*
1441 	 * Allow a small imbalance based on a simple pair of communicating
1442 	 * tasks that remain local when the destination is lightly loaded.
1443 	 */
1444 	if (imbalance <= NUMA_IMBALANCE_MIN)
1445 		return 0;
1446 
1447 	return imbalance;
1448 }
1449 #endif /* CONFIG_NUMA */
1450 
1451 #ifdef CONFIG_NUMA_BALANCING
1452 /*
1453  * Approximate time to scan a full NUMA task in ms. The task scan period is
1454  * calculated based on the tasks virtual memory size and
1455  * numa_balancing_scan_size.
1456  */
1457 unsigned int sysctl_numa_balancing_scan_period_min = 1000;
1458 unsigned int sysctl_numa_balancing_scan_period_max = 60000;
1459 
1460 /* Portion of address space to scan in MB */
1461 unsigned int sysctl_numa_balancing_scan_size = 256;
1462 
1463 /* Scan @scan_size MB every @scan_period after an initial @scan_delay in ms */
1464 unsigned int sysctl_numa_balancing_scan_delay = 1000;
1465 
1466 /* The page with hint page fault latency < threshold in ms is considered hot */
1467 unsigned int sysctl_numa_balancing_hot_threshold = MSEC_PER_SEC;
1468 
1469 struct numa_group {
1470 	refcount_t refcount;
1471 
1472 	spinlock_t lock; /* nr_tasks, tasks */
1473 	int nr_tasks;
1474 	pid_t gid;
1475 	int active_nodes;
1476 
1477 	struct rcu_head rcu;
1478 	unsigned long total_faults;
1479 	unsigned long max_faults_cpu;
1480 	/*
1481 	 * faults[] array is split into two regions: faults_mem and faults_cpu.
1482 	 *
1483 	 * Faults_cpu is used to decide whether memory should move
1484 	 * towards the CPU. As a consequence, these stats are weighted
1485 	 * more by CPU use than by memory faults.
1486 	 */
1487 	unsigned long faults[];
1488 };
1489 
1490 /*
1491  * For functions that can be called in multiple contexts that permit reading
1492  * ->numa_group (see struct task_struct for locking rules).
1493  */
1494 static struct numa_group *deref_task_numa_group(struct task_struct *p)
1495 {
1496 	return rcu_dereference_check(p->numa_group, p == current ||
1497 		(lockdep_is_held(__rq_lockp(task_rq(p))) && !READ_ONCE(p->on_cpu)));
1498 }
1499 
1500 static struct numa_group *deref_curr_numa_group(struct task_struct *p)
1501 {
1502 	return rcu_dereference_protected(p->numa_group, p == current);
1503 }
1504 
1505 static inline unsigned long group_faults_priv(struct numa_group *ng);
1506 static inline unsigned long group_faults_shared(struct numa_group *ng);
1507 
1508 static unsigned int task_nr_scan_windows(struct task_struct *p)
1509 {
1510 	unsigned long rss = 0;
1511 	unsigned long nr_scan_pages;
1512 
1513 	/*
1514 	 * Calculations based on RSS as non-present and empty pages are skipped
1515 	 * by the PTE scanner and NUMA hinting faults should be trapped based
1516 	 * on resident pages
1517 	 */
1518 	nr_scan_pages = MB_TO_PAGES(sysctl_numa_balancing_scan_size);
1519 	rss = get_mm_rss(p->mm);
1520 	if (!rss)
1521 		rss = nr_scan_pages;
1522 
1523 	rss = round_up(rss, nr_scan_pages);
1524 	return rss / nr_scan_pages;
1525 }
1526 
1527 /* For sanity's sake, never scan more PTEs than MAX_SCAN_WINDOW MB/sec. */
1528 #define MAX_SCAN_WINDOW 2560
1529 
1530 static unsigned int task_scan_min(struct task_struct *p)
1531 {
1532 	unsigned int scan_size = READ_ONCE(sysctl_numa_balancing_scan_size);
1533 	unsigned int scan, floor;
1534 	unsigned int windows = 1;
1535 
1536 	if (scan_size < MAX_SCAN_WINDOW)
1537 		windows = MAX_SCAN_WINDOW / scan_size;
1538 	floor = 1000 / windows;
1539 
1540 	scan = sysctl_numa_balancing_scan_period_min / task_nr_scan_windows(p);
1541 	return max_t(unsigned int, floor, scan);
1542 }
1543 
1544 static unsigned int task_scan_start(struct task_struct *p)
1545 {
1546 	unsigned long smin = task_scan_min(p);
1547 	unsigned long period = smin;
1548 	struct numa_group *ng;
1549 
1550 	/* Scale the maximum scan period with the amount of shared memory. */
1551 	rcu_read_lock();
1552 	ng = rcu_dereference_all(p->numa_group);
1553 	if (ng) {
1554 		unsigned long shared = group_faults_shared(ng);
1555 		unsigned long private = group_faults_priv(ng);
1556 
1557 		period *= refcount_read(&ng->refcount);
1558 		period *= shared + 1;
1559 		period /= private + shared + 1;
1560 	}
1561 	rcu_read_unlock();
1562 
1563 	return max(smin, period);
1564 }
1565 
1566 static unsigned int task_scan_max(struct task_struct *p)
1567 {
1568 	unsigned long smin = task_scan_min(p);
1569 	unsigned long smax;
1570 	struct numa_group *ng;
1571 
1572 	/* Watch for min being lower than max due to floor calculations */
1573 	smax = sysctl_numa_balancing_scan_period_max / task_nr_scan_windows(p);
1574 
1575 	/* Scale the maximum scan period with the amount of shared memory. */
1576 	ng = deref_curr_numa_group(p);
1577 	if (ng) {
1578 		unsigned long shared = group_faults_shared(ng);
1579 		unsigned long private = group_faults_priv(ng);
1580 		unsigned long period = smax;
1581 
1582 		period *= refcount_read(&ng->refcount);
1583 		period *= shared + 1;
1584 		period /= private + shared + 1;
1585 
1586 		smax = max(smax, period);
1587 	}
1588 
1589 	return max(smin, smax);
1590 }
1591 
1592 static void account_numa_enqueue(struct rq *rq, struct task_struct *p)
1593 {
1594 	rq->nr_numa_running += (p->numa_preferred_nid != NUMA_NO_NODE);
1595 	rq->nr_preferred_running += (p->numa_preferred_nid == task_node(p));
1596 }
1597 
1598 static void account_numa_dequeue(struct rq *rq, struct task_struct *p)
1599 {
1600 	rq->nr_numa_running -= (p->numa_preferred_nid != NUMA_NO_NODE);
1601 	rq->nr_preferred_running -= (p->numa_preferred_nid == task_node(p));
1602 }
1603 
1604 /* Shared or private faults. */
1605 #define NR_NUMA_HINT_FAULT_TYPES 2
1606 
1607 /* Memory and CPU locality */
1608 #define NR_NUMA_HINT_FAULT_STATS (NR_NUMA_HINT_FAULT_TYPES * 2)
1609 
1610 /* Averaged statistics, and temporary buffers. */
1611 #define NR_NUMA_HINT_FAULT_BUCKETS (NR_NUMA_HINT_FAULT_STATS * 2)
1612 
1613 pid_t task_numa_group_id(struct task_struct *p)
1614 {
1615 	struct numa_group *ng;
1616 	pid_t gid = 0;
1617 
1618 	rcu_read_lock();
1619 	ng = rcu_dereference_all(p->numa_group);
1620 	if (ng)
1621 		gid = ng->gid;
1622 	rcu_read_unlock();
1623 
1624 	return gid;
1625 }
1626 
1627 /*
1628  * The averaged statistics, shared & private, memory & CPU,
1629  * occupy the first half of the array. The second half of the
1630  * array is for current counters, which are averaged into the
1631  * first set by task_numa_placement.
1632  */
1633 static inline int task_faults_idx(enum numa_faults_stats s, int nid, int priv)
1634 {
1635 	return NR_NUMA_HINT_FAULT_TYPES * (s * nr_node_ids + nid) + priv;
1636 }
1637 
1638 static inline unsigned long task_faults(struct task_struct *p, int nid)
1639 {
1640 	if (!p->numa_faults)
1641 		return 0;
1642 
1643 	return p->numa_faults[task_faults_idx(NUMA_MEM, nid, 0)] +
1644 		p->numa_faults[task_faults_idx(NUMA_MEM, nid, 1)];
1645 }
1646 
1647 static inline unsigned long group_faults(struct task_struct *p, int nid)
1648 {
1649 	struct numa_group *ng = deref_task_numa_group(p);
1650 
1651 	if (!ng)
1652 		return 0;
1653 
1654 	return ng->faults[task_faults_idx(NUMA_MEM, nid, 0)] +
1655 		ng->faults[task_faults_idx(NUMA_MEM, nid, 1)];
1656 }
1657 
1658 static inline unsigned long group_faults_cpu(struct numa_group *group, int nid)
1659 {
1660 	return group->faults[task_faults_idx(NUMA_CPU, nid, 0)] +
1661 		group->faults[task_faults_idx(NUMA_CPU, nid, 1)];
1662 }
1663 
1664 static inline unsigned long group_faults_priv(struct numa_group *ng)
1665 {
1666 	unsigned long faults = 0;
1667 	int node;
1668 
1669 	for_each_online_node(node) {
1670 		faults += ng->faults[task_faults_idx(NUMA_MEM, node, 1)];
1671 	}
1672 
1673 	return faults;
1674 }
1675 
1676 static inline unsigned long group_faults_shared(struct numa_group *ng)
1677 {
1678 	unsigned long faults = 0;
1679 	int node;
1680 
1681 	for_each_online_node(node) {
1682 		faults += ng->faults[task_faults_idx(NUMA_MEM, node, 0)];
1683 	}
1684 
1685 	return faults;
1686 }
1687 
1688 /*
1689  * A node triggering more than 1/3 as many NUMA faults as the maximum is
1690  * considered part of a numa group's pseudo-interleaving set. Migrations
1691  * between these nodes are slowed down, to allow things to settle down.
1692  */
1693 #define ACTIVE_NODE_FRACTION 3
1694 
1695 static bool numa_is_active_node(int nid, struct numa_group *ng)
1696 {
1697 	return group_faults_cpu(ng, nid) * ACTIVE_NODE_FRACTION > ng->max_faults_cpu;
1698 }
1699 
1700 /* Handle placement on systems where not all nodes are directly connected. */
1701 static unsigned long score_nearby_nodes(struct task_struct *p, int nid,
1702 					int lim_dist, bool task)
1703 {
1704 	unsigned long score = 0;
1705 	int node, max_dist;
1706 
1707 	/*
1708 	 * All nodes are directly connected, and the same distance
1709 	 * from each other. No need for fancy placement algorithms.
1710 	 */
1711 	if (sched_numa_topology_type == NUMA_DIRECT)
1712 		return 0;
1713 
1714 	/* sched_max_numa_distance may be changed in parallel. */
1715 	max_dist = READ_ONCE(sched_max_numa_distance);
1716 	/*
1717 	 * This code is called for each node, introducing N^2 complexity,
1718 	 * which should be OK given the number of nodes rarely exceeds 8.
1719 	 */
1720 	for_each_online_node(node) {
1721 		unsigned long faults;
1722 		int dist = node_distance(nid, node);
1723 
1724 		/*
1725 		 * The furthest away nodes in the system are not interesting
1726 		 * for placement; nid was already counted.
1727 		 */
1728 		if (dist >= max_dist || node == nid)
1729 			continue;
1730 
1731 		/*
1732 		 * On systems with a backplane NUMA topology, compare groups
1733 		 * of nodes, and move tasks towards the group with the most
1734 		 * memory accesses. When comparing two nodes at distance
1735 		 * "hoplimit", only nodes closer by than "hoplimit" are part
1736 		 * of each group. Skip other nodes.
1737 		 */
1738 		if (sched_numa_topology_type == NUMA_BACKPLANE && dist >= lim_dist)
1739 			continue;
1740 
1741 		/* Add up the faults from nearby nodes. */
1742 		if (task)
1743 			faults = task_faults(p, node);
1744 		else
1745 			faults = group_faults(p, node);
1746 
1747 		/*
1748 		 * On systems with a glueless mesh NUMA topology, there are
1749 		 * no fixed "groups of nodes". Instead, nodes that are not
1750 		 * directly connected bounce traffic through intermediate
1751 		 * nodes; a numa_group can occupy any set of nodes.
1752 		 * The further away a node is, the less the faults count.
1753 		 * This seems to result in good task placement.
1754 		 */
1755 		if (sched_numa_topology_type == NUMA_GLUELESS_MESH) {
1756 			faults *= (max_dist - dist);
1757 			faults /= (max_dist - LOCAL_DISTANCE);
1758 		}
1759 
1760 		score += faults;
1761 	}
1762 
1763 	return score;
1764 }
1765 
1766 /*
1767  * These return the fraction of accesses done by a particular task, or
1768  * task group, on a particular numa node.  The group weight is given a
1769  * larger multiplier, in order to group tasks together that are almost
1770  * evenly spread out between numa nodes.
1771  */
1772 static inline unsigned long task_weight(struct task_struct *p, int nid,
1773 					int dist)
1774 {
1775 	unsigned long faults, total_faults;
1776 
1777 	if (!p->numa_faults)
1778 		return 0;
1779 
1780 	total_faults = p->total_numa_faults;
1781 
1782 	if (!total_faults)
1783 		return 0;
1784 
1785 	faults = task_faults(p, nid);
1786 	faults += score_nearby_nodes(p, nid, dist, true);
1787 
1788 	return 1000 * faults / total_faults;
1789 }
1790 
1791 static inline unsigned long group_weight(struct task_struct *p, int nid,
1792 					 int dist)
1793 {
1794 	struct numa_group *ng = deref_task_numa_group(p);
1795 	unsigned long faults, total_faults;
1796 
1797 	if (!ng)
1798 		return 0;
1799 
1800 	total_faults = ng->total_faults;
1801 
1802 	if (!total_faults)
1803 		return 0;
1804 
1805 	faults = group_faults(p, nid);
1806 	faults += score_nearby_nodes(p, nid, dist, false);
1807 
1808 	return 1000 * faults / total_faults;
1809 }
1810 
1811 /*
1812  * If memory tiering mode is enabled, cpupid of slow memory page is
1813  * used to record scan time instead of CPU and PID.  When tiering mode
1814  * is disabled at run time, the scan time (in cpupid) will be
1815  * interpreted as CPU and PID.  So CPU needs to be checked to avoid to
1816  * access out of array bound.
1817  */
1818 static inline bool cpupid_valid(int cpupid)
1819 {
1820 	return cpupid_to_cpu(cpupid) < nr_cpu_ids;
1821 }
1822 
1823 /*
1824  * For memory tiering mode, if there are enough free pages (more than
1825  * enough watermark defined here) in fast memory node, to take full
1826  * advantage of fast memory capacity, all recently accessed slow
1827  * memory pages will be migrated to fast memory node without
1828  * considering hot threshold.
1829  */
1830 static bool pgdat_free_space_enough(struct pglist_data *pgdat)
1831 {
1832 	int z;
1833 	unsigned long enough_wmark;
1834 
1835 	enough_wmark = max(1UL * 1024 * 1024 * 1024 >> PAGE_SHIFT,
1836 			   pgdat->node_present_pages >> 4);
1837 	for (z = pgdat->nr_zones - 1; z >= 0; z--) {
1838 		struct zone *zone = pgdat->node_zones + z;
1839 
1840 		if (!populated_zone(zone))
1841 			continue;
1842 
1843 		if (zone_watermark_ok(zone, 0,
1844 				      promo_wmark_pages(zone) + enough_wmark,
1845 				      ZONE_MOVABLE, 0))
1846 			return true;
1847 	}
1848 	return false;
1849 }
1850 
1851 /*
1852  * For memory tiering mode, when page tables are scanned, the scan
1853  * time will be recorded in struct page in addition to make page
1854  * PROT_NONE for slow memory page.  So when the page is accessed, in
1855  * hint page fault handler, the hint page fault latency is calculated
1856  * via,
1857  *
1858  *	hint page fault latency = hint page fault time - scan time
1859  *
1860  * The smaller the hint page fault latency, the higher the possibility
1861  * for the page to be hot.
1862  */
1863 static int numa_hint_fault_latency(struct folio *folio)
1864 {
1865 	int last_time, time;
1866 
1867 	time = jiffies_to_msecs(jiffies);
1868 	last_time = folio_xchg_access_time(folio, time);
1869 
1870 	return (time - last_time) & PAGE_ACCESS_TIME_MASK;
1871 }
1872 
1873 /*
1874  * For memory tiering mode, too high promotion/demotion throughput may
1875  * hurt application latency.  So we provide a mechanism to rate limit
1876  * the number of pages that are tried to be promoted.
1877  */
1878 static bool numa_promotion_rate_limit(struct pglist_data *pgdat,
1879 				      unsigned long rate_limit, int nr)
1880 {
1881 	unsigned long nr_cand;
1882 	unsigned int now, start;
1883 
1884 	now = jiffies_to_msecs(jiffies);
1885 	mod_node_page_state(pgdat, PGPROMOTE_CANDIDATE, nr);
1886 	nr_cand = node_page_state(pgdat, PGPROMOTE_CANDIDATE);
1887 	start = pgdat->nbp_rl_start;
1888 	if (now - start > MSEC_PER_SEC &&
1889 	    cmpxchg(&pgdat->nbp_rl_start, start, now) == start)
1890 		pgdat->nbp_rl_nr_cand = nr_cand;
1891 	if (nr_cand - pgdat->nbp_rl_nr_cand >= rate_limit)
1892 		return true;
1893 	return false;
1894 }
1895 
1896 #define NUMA_MIGRATION_ADJUST_STEPS	16
1897 
1898 static void numa_promotion_adjust_threshold(struct pglist_data *pgdat,
1899 					    unsigned long rate_limit,
1900 					    unsigned int ref_th)
1901 {
1902 	unsigned int now, start, th_period, unit_th, th;
1903 	unsigned long nr_cand, ref_cand, diff_cand;
1904 
1905 	now = jiffies_to_msecs(jiffies);
1906 	th_period = sysctl_numa_balancing_scan_period_max;
1907 	start = pgdat->nbp_th_start;
1908 	if (now - start > th_period &&
1909 	    cmpxchg(&pgdat->nbp_th_start, start, now) == start) {
1910 		ref_cand = rate_limit *
1911 			sysctl_numa_balancing_scan_period_max / MSEC_PER_SEC;
1912 		nr_cand = node_page_state(pgdat, PGPROMOTE_CANDIDATE);
1913 		diff_cand = nr_cand - pgdat->nbp_th_nr_cand;
1914 		unit_th = ref_th * 2 / NUMA_MIGRATION_ADJUST_STEPS;
1915 		th = pgdat->nbp_threshold ? : ref_th;
1916 		if (diff_cand > ref_cand * 11 / 10)
1917 			th = max(th - unit_th, unit_th);
1918 		else if (diff_cand < ref_cand * 9 / 10)
1919 			th = min(th + unit_th, ref_th * 2);
1920 		pgdat->nbp_th_nr_cand = nr_cand;
1921 		pgdat->nbp_threshold = th;
1922 	}
1923 }
1924 
1925 bool should_numa_migrate_memory(struct task_struct *p, struct folio *folio,
1926 				int src_nid, int dst_cpu)
1927 {
1928 	struct numa_group *ng = deref_curr_numa_group(p);
1929 	int dst_nid = cpu_to_node(dst_cpu);
1930 	int last_cpupid, this_cpupid;
1931 
1932 	/*
1933 	 * Cannot migrate to memoryless nodes.
1934 	 */
1935 	if (!node_state(dst_nid, N_MEMORY))
1936 		return false;
1937 
1938 	/*
1939 	 * The pages in slow memory node should be migrated according
1940 	 * to hot/cold instead of private/shared.
1941 	 */
1942 	if (folio_use_access_time(folio)) {
1943 		struct pglist_data *pgdat;
1944 		unsigned long rate_limit;
1945 		unsigned int latency, th, def_th;
1946 		long nr = folio_nr_pages(folio);
1947 
1948 		pgdat = NODE_DATA(dst_nid);
1949 		if (pgdat_free_space_enough(pgdat)) {
1950 			/* workload changed, reset hot threshold */
1951 			pgdat->nbp_threshold = 0;
1952 			mod_node_page_state(pgdat, PGPROMOTE_CANDIDATE_NRL, nr);
1953 			return true;
1954 		}
1955 
1956 		def_th = sysctl_numa_balancing_hot_threshold;
1957 		rate_limit = MB_TO_PAGES(sysctl_numa_balancing_promote_rate_limit);
1958 		numa_promotion_adjust_threshold(pgdat, rate_limit, def_th);
1959 
1960 		th = pgdat->nbp_threshold ? : def_th;
1961 		latency = numa_hint_fault_latency(folio);
1962 		if (latency >= th)
1963 			return false;
1964 
1965 		return !numa_promotion_rate_limit(pgdat, rate_limit, nr);
1966 	}
1967 
1968 	this_cpupid = cpu_pid_to_cpupid(dst_cpu, current->pid);
1969 	last_cpupid = folio_xchg_last_cpupid(folio, this_cpupid);
1970 
1971 	if (!(sysctl_numa_balancing_mode & NUMA_BALANCING_MEMORY_TIERING) &&
1972 	    !node_is_toptier(src_nid) && !cpupid_valid(last_cpupid))
1973 		return false;
1974 
1975 	/*
1976 	 * Allow first faults or private faults to migrate immediately early in
1977 	 * the lifetime of a task. The magic number 4 is based on waiting for
1978 	 * two full passes of the "multi-stage node selection" test that is
1979 	 * executed below.
1980 	 */
1981 	if ((p->numa_preferred_nid == NUMA_NO_NODE || p->numa_scan_seq <= 4) &&
1982 	    (cpupid_pid_unset(last_cpupid) || cpupid_match_pid(p, last_cpupid)))
1983 		return true;
1984 
1985 	/*
1986 	 * Multi-stage node selection is used in conjunction with a periodic
1987 	 * migration fault to build a temporal task<->page relation. By using
1988 	 * a two-stage filter we remove short/unlikely relations.
1989 	 *
1990 	 * Using P(p) ~ n_p / n_t as per frequentist probability, we can equate
1991 	 * a task's usage of a particular page (n_p) per total usage of this
1992 	 * page (n_t) (in a given time-span) to a probability.
1993 	 *
1994 	 * Our periodic faults will sample this probability and getting the
1995 	 * same result twice in a row, given these samples are fully
1996 	 * independent, is then given by P(n)^2, provided our sample period
1997 	 * is sufficiently short compared to the usage pattern.
1998 	 *
1999 	 * This quadric squishes small probabilities, making it less likely we
2000 	 * act on an unlikely task<->page relation.
2001 	 */
2002 	if (!cpupid_pid_unset(last_cpupid) &&
2003 				cpupid_to_nid(last_cpupid) != dst_nid)
2004 		return false;
2005 
2006 	/* Always allow migrate on private faults */
2007 	if (cpupid_match_pid(p, last_cpupid))
2008 		return true;
2009 
2010 	/* A shared fault, but p->numa_group has not been set up yet. */
2011 	if (!ng)
2012 		return true;
2013 
2014 	/*
2015 	 * Destination node is much more heavily used than the source
2016 	 * node? Allow migration.
2017 	 */
2018 	if (group_faults_cpu(ng, dst_nid) > group_faults_cpu(ng, src_nid) *
2019 					ACTIVE_NODE_FRACTION)
2020 		return true;
2021 
2022 	/*
2023 	 * Distribute memory according to CPU & memory use on each node,
2024 	 * with 3/4 hysteresis to avoid unnecessary memory migrations:
2025 	 *
2026 	 * faults_cpu(dst)   3   faults_cpu(src)
2027 	 * --------------- * - > ---------------
2028 	 * faults_mem(dst)   4   faults_mem(src)
2029 	 */
2030 	return group_faults_cpu(ng, dst_nid) * group_faults(p, src_nid) * 3 >
2031 	       group_faults_cpu(ng, src_nid) * group_faults(p, dst_nid) * 4;
2032 }
2033 
2034 /*
2035  * 'numa_type' describes the node at the moment of load balancing.
2036  */
2037 enum numa_type {
2038 	/* The node has spare capacity that can be used to run more tasks.  */
2039 	node_has_spare = 0,
2040 	/*
2041 	 * The node is fully used and the tasks don't compete for more CPU
2042 	 * cycles. Nevertheless, some tasks might wait before running.
2043 	 */
2044 	node_fully_busy,
2045 	/*
2046 	 * The node is overloaded and can't provide expected CPU cycles to all
2047 	 * tasks.
2048 	 */
2049 	node_overloaded
2050 };
2051 
2052 /* Cached statistics for all CPUs within a node */
2053 struct numa_stats {
2054 	unsigned long load;
2055 	unsigned long runnable;
2056 	unsigned long util;
2057 	/* Total compute capacity of CPUs on a node */
2058 	unsigned long compute_capacity;
2059 	unsigned int nr_running;
2060 	unsigned int weight;
2061 	enum numa_type node_type;
2062 	int idle_cpu;
2063 };
2064 
2065 struct task_numa_env {
2066 	struct task_struct *p;
2067 
2068 	int src_cpu, src_nid;
2069 	int dst_cpu, dst_nid;
2070 	int imb_numa_nr;
2071 
2072 	struct numa_stats src_stats, dst_stats;
2073 
2074 	int imbalance_pct;
2075 	int dist;
2076 
2077 	struct task_struct *best_task;
2078 	long best_imp;
2079 	int best_cpu;
2080 };
2081 
2082 static unsigned long cpu_load(struct rq *rq);
2083 static unsigned long cpu_runnable(struct rq *rq);
2084 
2085 static inline enum
2086 numa_type numa_classify(unsigned int imbalance_pct,
2087 			 struct numa_stats *ns)
2088 {
2089 	if ((ns->nr_running > ns->weight) &&
2090 	    (((ns->compute_capacity * 100) < (ns->util * imbalance_pct)) ||
2091 	     ((ns->compute_capacity * imbalance_pct) < (ns->runnable * 100))))
2092 		return node_overloaded;
2093 
2094 	if ((ns->nr_running < ns->weight) ||
2095 	    (((ns->compute_capacity * 100) > (ns->util * imbalance_pct)) &&
2096 	     ((ns->compute_capacity * imbalance_pct) > (ns->runnable * 100))))
2097 		return node_has_spare;
2098 
2099 	return node_fully_busy;
2100 }
2101 
2102 #ifdef CONFIG_SCHED_SMT
2103 /* Forward declarations of select_idle_sibling helpers */
2104 static inline bool test_idle_cores(int cpu);
2105 static inline int numa_idle_core(int idle_core, int cpu)
2106 {
2107 	if (!static_branch_likely(&sched_smt_present) ||
2108 	    idle_core >= 0 || !test_idle_cores(cpu))
2109 		return idle_core;
2110 
2111 	/*
2112 	 * Prefer cores instead of packing HT siblings
2113 	 * and triggering future load balancing.
2114 	 */
2115 	if (is_core_idle(cpu))
2116 		idle_core = cpu;
2117 
2118 	return idle_core;
2119 }
2120 #else /* !CONFIG_SCHED_SMT: */
2121 static inline int numa_idle_core(int idle_core, int cpu)
2122 {
2123 	return idle_core;
2124 }
2125 #endif /* !CONFIG_SCHED_SMT */
2126 
2127 /*
2128  * Gather all necessary information to make NUMA balancing placement
2129  * decisions that are compatible with standard load balancer. This
2130  * borrows code and logic from update_sg_lb_stats but sharing a
2131  * common implementation is impractical.
2132  */
2133 static void update_numa_stats(struct task_numa_env *env,
2134 			      struct numa_stats *ns, int nid,
2135 			      bool find_idle)
2136 {
2137 	int cpu, idle_core = -1;
2138 
2139 	memset(ns, 0, sizeof(*ns));
2140 	ns->idle_cpu = -1;
2141 
2142 	rcu_read_lock();
2143 	for_each_cpu(cpu, cpumask_of_node(nid)) {
2144 		struct rq *rq = cpu_rq(cpu);
2145 
2146 		ns->load += cpu_load(rq);
2147 		ns->runnable += cpu_runnable(rq);
2148 		ns->util += cpu_util_cfs(cpu);
2149 		ns->nr_running += rq->cfs.h_nr_runnable;
2150 		ns->compute_capacity += capacity_of(cpu);
2151 
2152 		if (find_idle && idle_core < 0 && !rq->nr_running && idle_cpu(cpu)) {
2153 			if (READ_ONCE(rq->numa_migrate_on) ||
2154 			    !cpumask_test_cpu(cpu, env->p->cpus_ptr))
2155 				continue;
2156 
2157 			if (ns->idle_cpu == -1)
2158 				ns->idle_cpu = cpu;
2159 
2160 			idle_core = numa_idle_core(idle_core, cpu);
2161 		}
2162 	}
2163 	rcu_read_unlock();
2164 
2165 	ns->weight = cpumask_weight(cpumask_of_node(nid));
2166 
2167 	ns->node_type = numa_classify(env->imbalance_pct, ns);
2168 
2169 	if (idle_core >= 0)
2170 		ns->idle_cpu = idle_core;
2171 }
2172 
2173 static void task_numa_assign(struct task_numa_env *env,
2174 			     struct task_struct *p, long imp)
2175 {
2176 	struct rq *rq = cpu_rq(env->dst_cpu);
2177 
2178 	/* Check if run-queue part of active NUMA balance. */
2179 	if (env->best_cpu != env->dst_cpu && xchg(&rq->numa_migrate_on, 1)) {
2180 		int cpu;
2181 		int start = env->dst_cpu;
2182 
2183 		/* Find alternative idle CPU. */
2184 		for_each_cpu_wrap(cpu, cpumask_of_node(env->dst_nid), start + 1) {
2185 			if (cpu == env->best_cpu || !idle_cpu(cpu) ||
2186 			    !cpumask_test_cpu(cpu, env->p->cpus_ptr)) {
2187 				continue;
2188 			}
2189 
2190 			env->dst_cpu = cpu;
2191 			rq = cpu_rq(env->dst_cpu);
2192 			if (!xchg(&rq->numa_migrate_on, 1))
2193 				goto assign;
2194 		}
2195 
2196 		/* Failed to find an alternative idle CPU */
2197 		return;
2198 	}
2199 
2200 assign:
2201 	/*
2202 	 * Clear previous best_cpu/rq numa-migrate flag, since task now
2203 	 * found a better CPU to move/swap.
2204 	 */
2205 	if (env->best_cpu != -1 && env->best_cpu != env->dst_cpu) {
2206 		rq = cpu_rq(env->best_cpu);
2207 		WRITE_ONCE(rq->numa_migrate_on, 0);
2208 	}
2209 
2210 	if (env->best_task)
2211 		put_task_struct(env->best_task);
2212 	if (p)
2213 		get_task_struct(p);
2214 
2215 	env->best_task = p;
2216 	env->best_imp = imp;
2217 	env->best_cpu = env->dst_cpu;
2218 }
2219 
2220 static bool load_too_imbalanced(long src_load, long dst_load,
2221 				struct task_numa_env *env)
2222 {
2223 	long imb, old_imb;
2224 	long orig_src_load, orig_dst_load;
2225 	long src_capacity, dst_capacity;
2226 
2227 	/*
2228 	 * The load is corrected for the CPU capacity available on each node.
2229 	 *
2230 	 * src_load        dst_load
2231 	 * ------------ vs ---------
2232 	 * src_capacity    dst_capacity
2233 	 */
2234 	src_capacity = env->src_stats.compute_capacity;
2235 	dst_capacity = env->dst_stats.compute_capacity;
2236 
2237 	imb = abs(dst_load * src_capacity - src_load * dst_capacity);
2238 
2239 	orig_src_load = env->src_stats.load;
2240 	orig_dst_load = env->dst_stats.load;
2241 
2242 	old_imb = abs(orig_dst_load * src_capacity - orig_src_load * dst_capacity);
2243 
2244 	/* Would this change make things worse? */
2245 	return (imb > old_imb);
2246 }
2247 
2248 /*
2249  * Maximum NUMA importance can be 1998 (2*999);
2250  * SMALLIMP @ 30 would be close to 1998/64.
2251  * Used to deter task migration.
2252  */
2253 #define SMALLIMP	30
2254 
2255 /*
2256  * This checks if the overall compute and NUMA accesses of the system would
2257  * be improved if the source tasks was migrated to the target dst_cpu taking
2258  * into account that it might be best if task running on the dst_cpu should
2259  * be exchanged with the source task
2260  */
2261 static bool task_numa_compare(struct task_numa_env *env,
2262 			      long taskimp, long groupimp, bool maymove)
2263 {
2264 	struct numa_group *cur_ng, *p_ng = deref_curr_numa_group(env->p);
2265 	struct rq *dst_rq = cpu_rq(env->dst_cpu);
2266 	long imp = p_ng ? groupimp : taskimp;
2267 	struct task_struct *cur;
2268 	long src_load, dst_load;
2269 	int dist = env->dist;
2270 	long moveimp = imp;
2271 	long load;
2272 	bool stopsearch = false;
2273 
2274 	if (READ_ONCE(dst_rq->numa_migrate_on))
2275 		return false;
2276 
2277 	rcu_read_lock();
2278 	cur = rcu_dereference_all(dst_rq->curr);
2279 	if (cur && ((cur->flags & (PF_EXITING | PF_KTHREAD)) ||
2280 		    !cur->mm))
2281 		cur = NULL;
2282 
2283 	/*
2284 	 * Because we have preemption enabled we can get migrated around and
2285 	 * end try selecting ourselves (current == env->p) as a swap candidate.
2286 	 */
2287 	if (cur == env->p) {
2288 		stopsearch = true;
2289 		goto unlock;
2290 	}
2291 
2292 	if (!cur) {
2293 		if (maymove && moveimp >= env->best_imp)
2294 			goto assign;
2295 		else
2296 			goto unlock;
2297 	}
2298 
2299 	/* Skip this swap candidate if cannot move to the source cpu. */
2300 	if (!cpumask_test_cpu(env->src_cpu, cur->cpus_ptr))
2301 		goto unlock;
2302 
2303 	/*
2304 	 * Skip this swap candidate if it is not moving to its preferred
2305 	 * node and the best task is.
2306 	 */
2307 	if (env->best_task &&
2308 	    env->best_task->numa_preferred_nid == env->src_nid &&
2309 	    cur->numa_preferred_nid != env->src_nid) {
2310 		goto unlock;
2311 	}
2312 
2313 	/*
2314 	 * "imp" is the fault differential for the source task between the
2315 	 * source and destination node. Calculate the total differential for
2316 	 * the source task and potential destination task. The more negative
2317 	 * the value is, the more remote accesses that would be expected to
2318 	 * be incurred if the tasks were swapped.
2319 	 *
2320 	 * If dst and source tasks are in the same NUMA group, or not
2321 	 * in any group then look only at task weights.
2322 	 */
2323 	cur_ng = rcu_dereference_all(cur->numa_group);
2324 	if (cur_ng == p_ng) {
2325 		/*
2326 		 * Do not swap within a group or between tasks that have
2327 		 * no group if there is spare capacity. Swapping does
2328 		 * not address the load imbalance and helps one task at
2329 		 * the cost of punishing another.
2330 		 */
2331 		if (env->dst_stats.node_type == node_has_spare)
2332 			goto unlock;
2333 
2334 		imp = taskimp + task_weight(cur, env->src_nid, dist) -
2335 		      task_weight(cur, env->dst_nid, dist);
2336 		/*
2337 		 * Add some hysteresis to prevent swapping the
2338 		 * tasks within a group over tiny differences.
2339 		 */
2340 		if (cur_ng)
2341 			imp -= imp / 16;
2342 	} else {
2343 		/*
2344 		 * Compare the group weights. If a task is all by itself
2345 		 * (not part of a group), use the task weight instead.
2346 		 */
2347 		if (cur_ng && p_ng)
2348 			imp += group_weight(cur, env->src_nid, dist) -
2349 			       group_weight(cur, env->dst_nid, dist);
2350 		else
2351 			imp += task_weight(cur, env->src_nid, dist) -
2352 			       task_weight(cur, env->dst_nid, dist);
2353 	}
2354 
2355 	/* Discourage picking a task already on its preferred node */
2356 	if (cur->numa_preferred_nid == env->dst_nid)
2357 		imp -= imp / 16;
2358 
2359 	/*
2360 	 * Encourage picking a task that moves to its preferred node.
2361 	 * This potentially makes imp larger than it's maximum of
2362 	 * 1998 (see SMALLIMP and task_weight for why) but in this
2363 	 * case, it does not matter.
2364 	 */
2365 	if (cur->numa_preferred_nid == env->src_nid)
2366 		imp += imp / 8;
2367 
2368 	if (maymove && moveimp > imp && moveimp > env->best_imp) {
2369 		imp = moveimp;
2370 		cur = NULL;
2371 		goto assign;
2372 	}
2373 
2374 	/*
2375 	 * Prefer swapping with a task moving to its preferred node over a
2376 	 * task that is not.
2377 	 */
2378 	if (env->best_task && cur->numa_preferred_nid == env->src_nid &&
2379 	    env->best_task->numa_preferred_nid != env->src_nid) {
2380 		goto assign;
2381 	}
2382 
2383 	/*
2384 	 * If the NUMA importance is less than SMALLIMP,
2385 	 * task migration might only result in ping pong
2386 	 * of tasks and also hurt performance due to cache
2387 	 * misses.
2388 	 */
2389 	if (imp < SMALLIMP || imp <= env->best_imp + SMALLIMP / 2)
2390 		goto unlock;
2391 
2392 	/*
2393 	 * In the overloaded case, try and keep the load balanced.
2394 	 */
2395 	load = task_h_load(env->p) - task_h_load(cur);
2396 	if (!load)
2397 		goto assign;
2398 
2399 	dst_load = env->dst_stats.load + load;
2400 	src_load = env->src_stats.load - load;
2401 
2402 	if (load_too_imbalanced(src_load, dst_load, env))
2403 		goto unlock;
2404 
2405 assign:
2406 	/* Evaluate an idle CPU for a task numa move. */
2407 	if (!cur) {
2408 		int cpu = env->dst_stats.idle_cpu;
2409 
2410 		/* Nothing cached so current CPU went idle since the search. */
2411 		if (cpu < 0)
2412 			cpu = env->dst_cpu;
2413 
2414 		/*
2415 		 * If the CPU is no longer truly idle and the previous best CPU
2416 		 * is, keep using it.
2417 		 */
2418 		if (!idle_cpu(cpu) && env->best_cpu >= 0 &&
2419 		    idle_cpu(env->best_cpu)) {
2420 			cpu = env->best_cpu;
2421 		}
2422 
2423 		env->dst_cpu = cpu;
2424 	}
2425 
2426 	task_numa_assign(env, cur, imp);
2427 
2428 	/*
2429 	 * If a move to idle is allowed because there is capacity or load
2430 	 * balance improves then stop the search. While a better swap
2431 	 * candidate may exist, a search is not free.
2432 	 */
2433 	if (maymove && !cur && env->best_cpu >= 0 && idle_cpu(env->best_cpu))
2434 		stopsearch = true;
2435 
2436 	/*
2437 	 * If a swap candidate must be identified and the current best task
2438 	 * moves its preferred node then stop the search.
2439 	 */
2440 	if (!maymove && env->best_task &&
2441 	    env->best_task->numa_preferred_nid == env->src_nid) {
2442 		stopsearch = true;
2443 	}
2444 unlock:
2445 	rcu_read_unlock();
2446 
2447 	return stopsearch;
2448 }
2449 
2450 static void task_numa_find_cpu(struct task_numa_env *env,
2451 				long taskimp, long groupimp)
2452 {
2453 	bool maymove = false;
2454 	int cpu;
2455 
2456 	/*
2457 	 * If dst node has spare capacity, then check if there is an
2458 	 * imbalance that would be overruled by the load balancer.
2459 	 */
2460 	if (env->dst_stats.node_type == node_has_spare) {
2461 		unsigned int imbalance;
2462 		int src_running, dst_running;
2463 
2464 		/*
2465 		 * Would movement cause an imbalance? Note that if src has
2466 		 * more running tasks that the imbalance is ignored as the
2467 		 * move improves the imbalance from the perspective of the
2468 		 * CPU load balancer.
2469 		 * */
2470 		src_running = env->src_stats.nr_running - 1;
2471 		dst_running = env->dst_stats.nr_running + 1;
2472 		imbalance = max(0, dst_running - src_running);
2473 		imbalance = adjust_numa_imbalance(imbalance, dst_running,
2474 						  env->imb_numa_nr);
2475 
2476 		/* Use idle CPU if there is no imbalance */
2477 		if (!imbalance) {
2478 			maymove = true;
2479 			if (env->dst_stats.idle_cpu >= 0) {
2480 				env->dst_cpu = env->dst_stats.idle_cpu;
2481 				task_numa_assign(env, NULL, 0);
2482 				return;
2483 			}
2484 		}
2485 	} else {
2486 		long src_load, dst_load, load;
2487 		/*
2488 		 * If the improvement from just moving env->p direction is better
2489 		 * than swapping tasks around, check if a move is possible.
2490 		 */
2491 		load = task_h_load(env->p);
2492 		dst_load = env->dst_stats.load + load;
2493 		src_load = env->src_stats.load - load;
2494 		maymove = !load_too_imbalanced(src_load, dst_load, env);
2495 	}
2496 
2497 	/* Skip CPUs if the source task cannot migrate */
2498 	for_each_cpu_and(cpu, cpumask_of_node(env->dst_nid), env->p->cpus_ptr) {
2499 		env->dst_cpu = cpu;
2500 		if (task_numa_compare(env, taskimp, groupimp, maymove))
2501 			break;
2502 	}
2503 }
2504 
2505 static int task_numa_migrate(struct task_struct *p)
2506 {
2507 	struct task_numa_env env = {
2508 		.p = p,
2509 
2510 		.src_cpu = task_cpu(p),
2511 		.src_nid = task_node(p),
2512 
2513 		.imbalance_pct = 112,
2514 
2515 		.best_task = NULL,
2516 		.best_imp = 0,
2517 		.best_cpu = -1,
2518 	};
2519 	unsigned long taskweight, groupweight;
2520 	struct sched_domain *sd;
2521 	long taskimp, groupimp;
2522 	struct numa_group *ng;
2523 	struct rq *best_rq;
2524 	int nid, ret, dist;
2525 
2526 	/*
2527 	 * Pick the lowest SD_NUMA domain, as that would have the smallest
2528 	 * imbalance and would be the first to start moving tasks about.
2529 	 *
2530 	 * And we want to avoid any moving of tasks about, as that would create
2531 	 * random movement of tasks -- counter the numa conditions we're trying
2532 	 * to satisfy here.
2533 	 */
2534 	rcu_read_lock();
2535 	sd = rcu_dereference_all(per_cpu(sd_numa, env.src_cpu));
2536 	if (sd) {
2537 		env.imbalance_pct = 100 + (sd->imbalance_pct - 100) / 2;
2538 		env.imb_numa_nr = sd->imb_numa_nr;
2539 	}
2540 	rcu_read_unlock();
2541 
2542 	/*
2543 	 * Cpusets can break the scheduler domain tree into smaller
2544 	 * balance domains, some of which do not cross NUMA boundaries.
2545 	 * Tasks that are "trapped" in such domains cannot be migrated
2546 	 * elsewhere, so there is no point in (re)trying.
2547 	 */
2548 	if (unlikely(!sd)) {
2549 		sched_setnuma(p, task_node(p));
2550 		return -EINVAL;
2551 	}
2552 
2553 	env.dst_nid = p->numa_preferred_nid;
2554 	dist = env.dist = node_distance(env.src_nid, env.dst_nid);
2555 	taskweight = task_weight(p, env.src_nid, dist);
2556 	groupweight = group_weight(p, env.src_nid, dist);
2557 	update_numa_stats(&env, &env.src_stats, env.src_nid, false);
2558 	taskimp = task_weight(p, env.dst_nid, dist) - taskweight;
2559 	groupimp = group_weight(p, env.dst_nid, dist) - groupweight;
2560 	update_numa_stats(&env, &env.dst_stats, env.dst_nid, true);
2561 
2562 	/* Try to find a spot on the preferred nid. */
2563 	task_numa_find_cpu(&env, taskimp, groupimp);
2564 
2565 	/*
2566 	 * Look at other nodes in these cases:
2567 	 * - there is no space available on the preferred_nid
2568 	 * - the task is part of a numa_group that is interleaved across
2569 	 *   multiple NUMA nodes; in order to better consolidate the group,
2570 	 *   we need to check other locations.
2571 	 */
2572 	ng = deref_curr_numa_group(p);
2573 	if (env.best_cpu == -1 || (ng && ng->active_nodes > 1)) {
2574 		for_each_node_state(nid, N_CPU) {
2575 			if (nid == env.src_nid || nid == p->numa_preferred_nid)
2576 				continue;
2577 
2578 			dist = node_distance(env.src_nid, env.dst_nid);
2579 			if (sched_numa_topology_type == NUMA_BACKPLANE &&
2580 						dist != env.dist) {
2581 				taskweight = task_weight(p, env.src_nid, dist);
2582 				groupweight = group_weight(p, env.src_nid, dist);
2583 			}
2584 
2585 			/* Only consider nodes where both task and groups benefit */
2586 			taskimp = task_weight(p, nid, dist) - taskweight;
2587 			groupimp = group_weight(p, nid, dist) - groupweight;
2588 			if (taskimp < 0 && groupimp < 0)
2589 				continue;
2590 
2591 			env.dist = dist;
2592 			env.dst_nid = nid;
2593 			update_numa_stats(&env, &env.dst_stats, env.dst_nid, true);
2594 			task_numa_find_cpu(&env, taskimp, groupimp);
2595 		}
2596 	}
2597 
2598 	/*
2599 	 * If the task is part of a workload that spans multiple NUMA nodes,
2600 	 * and is migrating into one of the workload's active nodes, remember
2601 	 * this node as the task's preferred numa node, so the workload can
2602 	 * settle down.
2603 	 * A task that migrated to a second choice node will be better off
2604 	 * trying for a better one later. Do not set the preferred node here.
2605 	 */
2606 	if (ng) {
2607 		if (env.best_cpu == -1)
2608 			nid = env.src_nid;
2609 		else
2610 			nid = cpu_to_node(env.best_cpu);
2611 
2612 		if (nid != p->numa_preferred_nid)
2613 			sched_setnuma(p, nid);
2614 	}
2615 
2616 	/* No better CPU than the current one was found. */
2617 	if (env.best_cpu == -1) {
2618 		trace_sched_stick_numa(p, env.src_cpu, NULL, -1);
2619 		return -EAGAIN;
2620 	}
2621 
2622 	best_rq = cpu_rq(env.best_cpu);
2623 	if (env.best_task == NULL) {
2624 		ret = migrate_task_to(p, env.best_cpu);
2625 		WRITE_ONCE(best_rq->numa_migrate_on, 0);
2626 		if (ret != 0)
2627 			trace_sched_stick_numa(p, env.src_cpu, NULL, env.best_cpu);
2628 		return ret;
2629 	}
2630 
2631 	ret = migrate_swap(p, env.best_task, env.best_cpu, env.src_cpu);
2632 	WRITE_ONCE(best_rq->numa_migrate_on, 0);
2633 
2634 	if (ret != 0)
2635 		trace_sched_stick_numa(p, env.src_cpu, env.best_task, env.best_cpu);
2636 	put_task_struct(env.best_task);
2637 	return ret;
2638 }
2639 
2640 /* Attempt to migrate a task to a CPU on the preferred node. */
2641 static void numa_migrate_preferred(struct task_struct *p)
2642 {
2643 	unsigned long interval = HZ;
2644 
2645 	/* This task has no NUMA fault statistics yet */
2646 	if (unlikely(p->numa_preferred_nid == NUMA_NO_NODE || !p->numa_faults))
2647 		return;
2648 
2649 	/* Periodically retry migrating the task to the preferred node */
2650 	interval = min(interval, msecs_to_jiffies(p->numa_scan_period) / 16);
2651 	p->numa_migrate_retry = jiffies + interval;
2652 
2653 	/* Success if task is already running on preferred CPU */
2654 	if (task_node(p) == p->numa_preferred_nid)
2655 		return;
2656 
2657 	/* Otherwise, try migrate to a CPU on the preferred node */
2658 	task_numa_migrate(p);
2659 }
2660 
2661 /*
2662  * Find out how many nodes the workload is actively running on. Do this by
2663  * tracking the nodes from which NUMA hinting faults are triggered. This can
2664  * be different from the set of nodes where the workload's memory is currently
2665  * located.
2666  */
2667 static void numa_group_count_active_nodes(struct numa_group *numa_group)
2668 {
2669 	unsigned long faults, max_faults = 0;
2670 	int nid, active_nodes = 0;
2671 
2672 	for_each_node_state(nid, N_CPU) {
2673 		faults = group_faults_cpu(numa_group, nid);
2674 		if (faults > max_faults)
2675 			max_faults = faults;
2676 	}
2677 
2678 	for_each_node_state(nid, N_CPU) {
2679 		faults = group_faults_cpu(numa_group, nid);
2680 		if (faults * ACTIVE_NODE_FRACTION > max_faults)
2681 			active_nodes++;
2682 	}
2683 
2684 	numa_group->max_faults_cpu = max_faults;
2685 	numa_group->active_nodes = active_nodes;
2686 }
2687 
2688 /*
2689  * When adapting the scan rate, the period is divided into NUMA_PERIOD_SLOTS
2690  * increments. The more local the fault statistics are, the higher the scan
2691  * period will be for the next scan window. If local/(local+remote) ratio is
2692  * below NUMA_PERIOD_THRESHOLD (where range of ratio is 1..NUMA_PERIOD_SLOTS)
2693  * the scan period will decrease. Aim for 70% local accesses.
2694  */
2695 #define NUMA_PERIOD_SLOTS 10
2696 #define NUMA_PERIOD_THRESHOLD 7
2697 
2698 /*
2699  * Increase the scan period (slow down scanning) if the majority of
2700  * our memory is already on our local node, or if the majority of
2701  * the page accesses are shared with other processes.
2702  * Otherwise, decrease the scan period.
2703  */
2704 static void update_task_scan_period(struct task_struct *p,
2705 			unsigned long shared, unsigned long private)
2706 {
2707 	unsigned int period_slot;
2708 	int lr_ratio, ps_ratio;
2709 	int diff;
2710 
2711 	unsigned long remote = p->numa_faults_locality[0];
2712 	unsigned long local = p->numa_faults_locality[1];
2713 
2714 	/*
2715 	 * If there were no record hinting faults then either the task is
2716 	 * completely idle or all activity is in areas that are not of interest
2717 	 * to automatic numa balancing. Related to that, if there were failed
2718 	 * migration then it implies we are migrating too quickly or the local
2719 	 * node is overloaded. In either case, scan slower
2720 	 */
2721 	if (local + shared == 0 || p->numa_faults_locality[2]) {
2722 		p->numa_scan_period = min(p->numa_scan_period_max,
2723 			p->numa_scan_period << 1);
2724 
2725 		p->mm->numa_next_scan = jiffies +
2726 			msecs_to_jiffies(p->numa_scan_period);
2727 
2728 		return;
2729 	}
2730 
2731 	/*
2732 	 * Prepare to scale scan period relative to the current period.
2733 	 *	 == NUMA_PERIOD_THRESHOLD scan period stays the same
2734 	 *       <  NUMA_PERIOD_THRESHOLD scan period decreases (scan faster)
2735 	 *	 >= NUMA_PERIOD_THRESHOLD scan period increases (scan slower)
2736 	 */
2737 	period_slot = DIV_ROUND_UP(p->numa_scan_period, NUMA_PERIOD_SLOTS);
2738 	lr_ratio = (local * NUMA_PERIOD_SLOTS) / (local + remote);
2739 	ps_ratio = (private * NUMA_PERIOD_SLOTS) / (private + shared);
2740 
2741 	if (ps_ratio >= NUMA_PERIOD_THRESHOLD) {
2742 		/*
2743 		 * Most memory accesses are local. There is no need to
2744 		 * do fast NUMA scanning, since memory is already local.
2745 		 */
2746 		int slot = ps_ratio - NUMA_PERIOD_THRESHOLD;
2747 		if (!slot)
2748 			slot = 1;
2749 		diff = slot * period_slot;
2750 	} else if (lr_ratio >= NUMA_PERIOD_THRESHOLD) {
2751 		/*
2752 		 * Most memory accesses are shared with other tasks.
2753 		 * There is no point in continuing fast NUMA scanning,
2754 		 * since other tasks may just move the memory elsewhere.
2755 		 */
2756 		int slot = lr_ratio - NUMA_PERIOD_THRESHOLD;
2757 		if (!slot)
2758 			slot = 1;
2759 		diff = slot * period_slot;
2760 	} else {
2761 		/*
2762 		 * Private memory faults exceed (SLOTS-THRESHOLD)/SLOTS,
2763 		 * yet they are not on the local NUMA node. Speed up
2764 		 * NUMA scanning to get the memory moved over.
2765 		 */
2766 		int ratio = max(lr_ratio, ps_ratio);
2767 		diff = -(NUMA_PERIOD_THRESHOLD - ratio) * period_slot;
2768 	}
2769 
2770 	p->numa_scan_period = clamp(p->numa_scan_period + diff,
2771 			task_scan_min(p), task_scan_max(p));
2772 	memset(p->numa_faults_locality, 0, sizeof(p->numa_faults_locality));
2773 }
2774 
2775 /*
2776  * Get the fraction of time the task has been running since the last
2777  * NUMA placement cycle. The scheduler keeps similar statistics, but
2778  * decays those on a 32ms period, which is orders of magnitude off
2779  * from the dozens-of-seconds NUMA balancing period. Use the scheduler
2780  * stats only if the task is so new there are no NUMA statistics yet.
2781  */
2782 static u64 numa_get_avg_runtime(struct task_struct *p, u64 *period)
2783 {
2784 	u64 runtime, delta, now;
2785 	/* Use the start of this time slice to avoid calculations. */
2786 	now = p->se.exec_start;
2787 	runtime = p->se.sum_exec_runtime;
2788 
2789 	if (p->last_task_numa_placement) {
2790 		delta = runtime - p->last_sum_exec_runtime;
2791 		*period = now - p->last_task_numa_placement;
2792 
2793 		/* Avoid time going backwards, prevent potential divide error: */
2794 		if (unlikely((s64)*period < 0))
2795 			*period = 0;
2796 	} else {
2797 		delta = p->se.avg.load_sum;
2798 		*period = LOAD_AVG_MAX;
2799 	}
2800 
2801 	p->last_sum_exec_runtime = runtime;
2802 	p->last_task_numa_placement = now;
2803 
2804 	return delta;
2805 }
2806 
2807 /*
2808  * Determine the preferred nid for a task in a numa_group. This needs to
2809  * be done in a way that produces consistent results with group_weight,
2810  * otherwise workloads might not converge.
2811  */
2812 static int preferred_group_nid(struct task_struct *p, int nid)
2813 {
2814 	nodemask_t nodes;
2815 	int dist;
2816 
2817 	/* Direct connections between all NUMA nodes. */
2818 	if (sched_numa_topology_type == NUMA_DIRECT)
2819 		return nid;
2820 
2821 	/*
2822 	 * On a system with glueless mesh NUMA topology, group_weight
2823 	 * scores nodes according to the number of NUMA hinting faults on
2824 	 * both the node itself, and on nearby nodes.
2825 	 */
2826 	if (sched_numa_topology_type == NUMA_GLUELESS_MESH) {
2827 		unsigned long score, max_score = 0;
2828 		int node, max_node = nid;
2829 
2830 		dist = sched_max_numa_distance;
2831 
2832 		for_each_node_state(node, N_CPU) {
2833 			score = group_weight(p, node, dist);
2834 			if (score > max_score) {
2835 				max_score = score;
2836 				max_node = node;
2837 			}
2838 		}
2839 		return max_node;
2840 	}
2841 
2842 	/*
2843 	 * Finding the preferred nid in a system with NUMA backplane
2844 	 * interconnect topology is more involved. The goal is to locate
2845 	 * tasks from numa_groups near each other in the system, and
2846 	 * untangle workloads from different sides of the system. This requires
2847 	 * searching down the hierarchy of node groups, recursively searching
2848 	 * inside the highest scoring group of nodes. The nodemask tricks
2849 	 * keep the complexity of the search down.
2850 	 */
2851 	nodes = node_states[N_CPU];
2852 	for (dist = sched_max_numa_distance; dist > LOCAL_DISTANCE; dist--) {
2853 		unsigned long max_faults = 0;
2854 		nodemask_t max_group = NODE_MASK_NONE;
2855 		int a, b;
2856 
2857 		/* Are there nodes at this distance from each other? */
2858 		if (!find_numa_distance(dist))
2859 			continue;
2860 
2861 		for_each_node_mask(a, nodes) {
2862 			unsigned long faults = 0;
2863 			nodemask_t this_group;
2864 			nodes_clear(this_group);
2865 
2866 			/* Sum group's NUMA faults; includes a==b case. */
2867 			for_each_node_mask(b, nodes) {
2868 				if (node_distance(a, b) < dist) {
2869 					faults += group_faults(p, b);
2870 					node_set(b, this_group);
2871 					node_clear(b, nodes);
2872 				}
2873 			}
2874 
2875 			/* Remember the top group. */
2876 			if (faults > max_faults) {
2877 				max_faults = faults;
2878 				max_group = this_group;
2879 				/*
2880 				 * subtle: at the smallest distance there is
2881 				 * just one node left in each "group", the
2882 				 * winner is the preferred nid.
2883 				 */
2884 				nid = a;
2885 			}
2886 		}
2887 		/* Next round, evaluate the nodes within max_group. */
2888 		if (!max_faults)
2889 			break;
2890 		nodes = max_group;
2891 	}
2892 	return nid;
2893 }
2894 
2895 static void task_numa_placement(struct task_struct *p)
2896 	__context_unsafe(/* conditional locking */)
2897 {
2898 	int seq, nid, max_nid = NUMA_NO_NODE;
2899 	unsigned long max_faults = 0;
2900 	unsigned long fault_types[2] = { 0, 0 };
2901 	unsigned long total_faults;
2902 	u64 runtime, period;
2903 	spinlock_t *group_lock = NULL;
2904 	struct numa_group *ng;
2905 
2906 	/*
2907 	 * The p->mm->numa_scan_seq field gets updated without
2908 	 * exclusive access. Use READ_ONCE() here to ensure
2909 	 * that the field is read in a single access:
2910 	 */
2911 	seq = READ_ONCE(p->mm->numa_scan_seq);
2912 	if (p->numa_scan_seq == seq)
2913 		return;
2914 	p->numa_scan_seq = seq;
2915 	p->numa_scan_period_max = task_scan_max(p);
2916 
2917 	total_faults = p->numa_faults_locality[0] +
2918 		       p->numa_faults_locality[1];
2919 	runtime = numa_get_avg_runtime(p, &period);
2920 
2921 	/* If the task is part of a group prevent parallel updates to group stats */
2922 	ng = deref_curr_numa_group(p);
2923 	if (ng) {
2924 		group_lock = &ng->lock;
2925 		spin_lock_irq(group_lock);
2926 	}
2927 
2928 	/* Find the node with the highest number of faults */
2929 	for_each_online_node(nid) {
2930 		/* Keep track of the offsets in numa_faults array */
2931 		int mem_idx, membuf_idx, cpu_idx, cpubuf_idx;
2932 		unsigned long faults = 0, group_faults = 0;
2933 		int priv;
2934 
2935 		for (priv = 0; priv < NR_NUMA_HINT_FAULT_TYPES; priv++) {
2936 			long diff, f_diff, f_weight;
2937 
2938 			mem_idx = task_faults_idx(NUMA_MEM, nid, priv);
2939 			membuf_idx = task_faults_idx(NUMA_MEMBUF, nid, priv);
2940 			cpu_idx = task_faults_idx(NUMA_CPU, nid, priv);
2941 			cpubuf_idx = task_faults_idx(NUMA_CPUBUF, nid, priv);
2942 
2943 			/* Decay existing window, copy faults since last scan */
2944 			diff = p->numa_faults[membuf_idx] - p->numa_faults[mem_idx] / 2;
2945 			fault_types[priv] += p->numa_faults[membuf_idx];
2946 			p->numa_faults[membuf_idx] = 0;
2947 
2948 			/*
2949 			 * Normalize the faults_from, so all tasks in a group
2950 			 * count according to CPU use, instead of by the raw
2951 			 * number of faults. Tasks with little runtime have
2952 			 * little over-all impact on throughput, and thus their
2953 			 * faults are less important.
2954 			 */
2955 			f_weight = div64_u64(runtime << 16, period + 1);
2956 			f_weight = (f_weight * p->numa_faults[cpubuf_idx]) /
2957 				   (total_faults + 1);
2958 			f_diff = f_weight - p->numa_faults[cpu_idx] / 2;
2959 			p->numa_faults[cpubuf_idx] = 0;
2960 
2961 			p->numa_faults[mem_idx] += diff;
2962 			p->numa_faults[cpu_idx] += f_diff;
2963 			faults += p->numa_faults[mem_idx];
2964 			p->total_numa_faults += diff;
2965 			if (ng) {
2966 				/*
2967 				 * safe because we can only change our own group
2968 				 *
2969 				 * mem_idx represents the offset for a given
2970 				 * nid and priv in a specific region because it
2971 				 * is at the beginning of the numa_faults array.
2972 				 */
2973 				ng->faults[mem_idx] += diff;
2974 				ng->faults[cpu_idx] += f_diff;
2975 				ng->total_faults += diff;
2976 				group_faults += ng->faults[mem_idx];
2977 			}
2978 		}
2979 
2980 		if (!ng) {
2981 			if (faults > max_faults) {
2982 				max_faults = faults;
2983 				max_nid = nid;
2984 			}
2985 		} else if (group_faults > max_faults) {
2986 			max_faults = group_faults;
2987 			max_nid = nid;
2988 		}
2989 	}
2990 
2991 	/* Cannot migrate task to CPU-less node */
2992 	max_nid = numa_nearest_node(max_nid, N_CPU);
2993 
2994 	if (ng) {
2995 		numa_group_count_active_nodes(ng);
2996 		spin_unlock_irq(group_lock);
2997 		max_nid = preferred_group_nid(p, max_nid);
2998 	}
2999 
3000 	if (max_faults) {
3001 		/* Set the new preferred node */
3002 		if (max_nid != p->numa_preferred_nid)
3003 			sched_setnuma(p, max_nid);
3004 	}
3005 
3006 	update_task_scan_period(p, fault_types[0], fault_types[1]);
3007 }
3008 
3009 static inline int get_numa_group(struct numa_group *grp)
3010 {
3011 	return refcount_inc_not_zero(&grp->refcount);
3012 }
3013 
3014 static inline void put_numa_group(struct numa_group *grp)
3015 {
3016 	if (refcount_dec_and_test(&grp->refcount))
3017 		kfree_rcu(grp, rcu);
3018 }
3019 
3020 static void task_numa_group(struct task_struct *p, int cpupid, int flags,
3021 			int *priv)
3022 {
3023 	struct numa_group *grp, *my_grp;
3024 	struct task_struct *tsk;
3025 	bool join = false;
3026 	int cpu = cpupid_to_cpu(cpupid);
3027 	int i;
3028 
3029 	if (unlikely(!deref_curr_numa_group(p))) {
3030 		unsigned int size = sizeof(struct numa_group) +
3031 				    NR_NUMA_HINT_FAULT_STATS *
3032 				    nr_node_ids * sizeof(unsigned long);
3033 
3034 		grp = kzalloc(size, GFP_KERNEL | __GFP_NOWARN);
3035 		if (!grp)
3036 			return;
3037 
3038 		refcount_set(&grp->refcount, 1);
3039 		grp->active_nodes = 1;
3040 		grp->max_faults_cpu = 0;
3041 		spin_lock_init(&grp->lock);
3042 		grp->gid = p->pid;
3043 
3044 		for (i = 0; i < NR_NUMA_HINT_FAULT_STATS * nr_node_ids; i++)
3045 			grp->faults[i] = p->numa_faults[i];
3046 
3047 		grp->total_faults = p->total_numa_faults;
3048 
3049 		grp->nr_tasks++;
3050 		rcu_assign_pointer(p->numa_group, grp);
3051 	}
3052 
3053 	rcu_read_lock();
3054 	tsk = READ_ONCE(cpu_rq(cpu)->curr);
3055 
3056 	if (!cpupid_match_pid(tsk, cpupid))
3057 		goto no_join;
3058 
3059 	grp = rcu_dereference_all(tsk->numa_group);
3060 	if (!grp)
3061 		goto no_join;
3062 
3063 	my_grp = deref_curr_numa_group(p);
3064 	if (grp == my_grp)
3065 		goto no_join;
3066 
3067 	/*
3068 	 * Only join the other group if its bigger; if we're the bigger group,
3069 	 * the other task will join us.
3070 	 */
3071 	if (my_grp->nr_tasks > grp->nr_tasks)
3072 		goto no_join;
3073 
3074 	/*
3075 	 * Tie-break on the grp address.
3076 	 */
3077 	if (my_grp->nr_tasks == grp->nr_tasks && my_grp > grp)
3078 		goto no_join;
3079 
3080 	/* Always join threads in the same process. */
3081 	if (tsk->mm == current->mm)
3082 		join = true;
3083 
3084 	/* Simple filter to avoid false positives due to PID collisions */
3085 	if (flags & TNF_SHARED)
3086 		join = true;
3087 
3088 	/* Update priv based on whether false sharing was detected */
3089 	*priv = !join;
3090 
3091 	if (join && !get_numa_group(grp))
3092 		goto no_join;
3093 
3094 	rcu_read_unlock();
3095 
3096 	if (!join)
3097 		return;
3098 
3099 	WARN_ON_ONCE(irqs_disabled());
3100 	double_lock_irq(&my_grp->lock, &grp->lock);
3101 
3102 	for (i = 0; i < NR_NUMA_HINT_FAULT_STATS * nr_node_ids; i++) {
3103 		my_grp->faults[i] -= p->numa_faults[i];
3104 		grp->faults[i] += p->numa_faults[i];
3105 	}
3106 	my_grp->total_faults -= p->total_numa_faults;
3107 	grp->total_faults += p->total_numa_faults;
3108 
3109 	my_grp->nr_tasks--;
3110 	grp->nr_tasks++;
3111 
3112 	spin_unlock(&my_grp->lock);
3113 	spin_unlock_irq(&grp->lock);
3114 
3115 	rcu_assign_pointer(p->numa_group, grp);
3116 
3117 	put_numa_group(my_grp);
3118 	return;
3119 
3120 no_join:
3121 	rcu_read_unlock();
3122 	return;
3123 }
3124 
3125 /*
3126  * Get rid of NUMA statistics associated with a task (either current or dead).
3127  * If @final is set, the task is dead and has reached refcount zero, so we can
3128  * safely free all relevant data structures. Otherwise, there might be
3129  * concurrent reads from places like load balancing and procfs, and we should
3130  * reset the data back to default state without freeing ->numa_faults.
3131  */
3132 void task_numa_free(struct task_struct *p, bool final)
3133 {
3134 	/* safe: p either is current or is being freed by current */
3135 	struct numa_group *grp = rcu_dereference_raw(p->numa_group);
3136 	unsigned long *numa_faults = p->numa_faults;
3137 	unsigned long flags;
3138 	int i;
3139 
3140 	if (!numa_faults)
3141 		return;
3142 
3143 	if (grp) {
3144 		spin_lock_irqsave(&grp->lock, flags);
3145 		for (i = 0; i < NR_NUMA_HINT_FAULT_STATS * nr_node_ids; i++)
3146 			grp->faults[i] -= p->numa_faults[i];
3147 		grp->total_faults -= p->total_numa_faults;
3148 
3149 		grp->nr_tasks--;
3150 		spin_unlock_irqrestore(&grp->lock, flags);
3151 		RCU_INIT_POINTER(p->numa_group, NULL);
3152 		put_numa_group(grp);
3153 	}
3154 
3155 	if (final) {
3156 		p->numa_faults = NULL;
3157 		kfree(numa_faults);
3158 	} else {
3159 		p->total_numa_faults = 0;
3160 		for (i = 0; i < NR_NUMA_HINT_FAULT_STATS * nr_node_ids; i++)
3161 			numa_faults[i] = 0;
3162 	}
3163 }
3164 
3165 /*
3166  * Got a PROT_NONE fault for a page on @node.
3167  */
3168 void task_numa_fault(int last_cpupid, int mem_node, int pages, int flags)
3169 {
3170 	struct task_struct *p = current;
3171 	bool migrated = flags & TNF_MIGRATED;
3172 	int cpu_node = task_node(current);
3173 	int local = !!(flags & TNF_FAULT_LOCAL);
3174 	struct numa_group *ng;
3175 	int priv;
3176 
3177 	if (!static_branch_likely(&sched_numa_balancing))
3178 		return;
3179 
3180 	/* for example, ksmd faulting in a user's mm */
3181 	if (!p->mm)
3182 		return;
3183 
3184 	/*
3185 	 * NUMA faults statistics are unnecessary for the slow memory
3186 	 * node for memory tiering mode.
3187 	 */
3188 	if (!node_is_toptier(mem_node) &&
3189 	    (sysctl_numa_balancing_mode & NUMA_BALANCING_MEMORY_TIERING ||
3190 	     !cpupid_valid(last_cpupid)))
3191 		return;
3192 
3193 	/* Allocate buffer to track faults on a per-node basis */
3194 	if (unlikely(!p->numa_faults)) {
3195 		int size = sizeof(*p->numa_faults) *
3196 			   NR_NUMA_HINT_FAULT_BUCKETS * nr_node_ids;
3197 
3198 		p->numa_faults = kzalloc(size, GFP_KERNEL|__GFP_NOWARN);
3199 		if (!p->numa_faults)
3200 			return;
3201 
3202 		p->total_numa_faults = 0;
3203 		memset(p->numa_faults_locality, 0, sizeof(p->numa_faults_locality));
3204 	}
3205 
3206 	/*
3207 	 * First accesses are treated as private, otherwise consider accesses
3208 	 * to be private if the accessing pid has not changed
3209 	 */
3210 	if (unlikely(last_cpupid == (-1 & LAST_CPUPID_MASK))) {
3211 		priv = 1;
3212 	} else {
3213 		priv = cpupid_match_pid(p, last_cpupid);
3214 		if (!priv && !(flags & TNF_NO_GROUP))
3215 			task_numa_group(p, last_cpupid, flags, &priv);
3216 	}
3217 
3218 	/*
3219 	 * If a workload spans multiple NUMA nodes, a shared fault that
3220 	 * occurs wholly within the set of nodes that the workload is
3221 	 * actively using should be counted as local. This allows the
3222 	 * scan rate to slow down when a workload has settled down.
3223 	 */
3224 	ng = deref_curr_numa_group(p);
3225 	if (!priv && !local && ng && ng->active_nodes > 1 &&
3226 				numa_is_active_node(cpu_node, ng) &&
3227 				numa_is_active_node(mem_node, ng))
3228 		local = 1;
3229 
3230 	/*
3231 	 * Retry to migrate task to preferred node periodically, in case it
3232 	 * previously failed, or the scheduler moved us.
3233 	 */
3234 	if (time_after(jiffies, p->numa_migrate_retry)) {
3235 		task_numa_placement(p);
3236 		numa_migrate_preferred(p);
3237 	}
3238 
3239 	if (migrated)
3240 		p->numa_pages_migrated += pages;
3241 	if (flags & TNF_MIGRATE_FAIL)
3242 		p->numa_faults_locality[2] += pages;
3243 
3244 	p->numa_faults[task_faults_idx(NUMA_MEMBUF, mem_node, priv)] += pages;
3245 	p->numa_faults[task_faults_idx(NUMA_CPUBUF, cpu_node, priv)] += pages;
3246 	p->numa_faults_locality[local] += pages;
3247 }
3248 
3249 static void reset_ptenuma_scan(struct task_struct *p)
3250 {
3251 	/*
3252 	 * We only did a read acquisition of the mmap sem, so
3253 	 * p->mm->numa_scan_seq is written to without exclusive access
3254 	 * and the update is not guaranteed to be atomic. That's not
3255 	 * much of an issue though, since this is just used for
3256 	 * statistical sampling. Use READ_ONCE/WRITE_ONCE, which are not
3257 	 * expensive, to avoid any form of compiler optimizations:
3258 	 */
3259 	WRITE_ONCE(p->mm->numa_scan_seq, READ_ONCE(p->mm->numa_scan_seq) + 1);
3260 	p->mm->numa_scan_offset = 0;
3261 }
3262 
3263 static bool vma_is_accessed(struct mm_struct *mm, struct vm_area_struct *vma)
3264 {
3265 	unsigned long pids;
3266 	/*
3267 	 * Allow unconditional access first two times, so that all the (pages)
3268 	 * of VMAs get prot_none fault introduced irrespective of accesses.
3269 	 * This is also done to avoid any side effect of task scanning
3270 	 * amplifying the unfairness of disjoint set of VMAs' access.
3271 	 */
3272 	if ((READ_ONCE(current->mm->numa_scan_seq) - vma->numab_state->start_scan_seq) < 2)
3273 		return true;
3274 
3275 	pids = vma->numab_state->pids_active[0] | vma->numab_state->pids_active[1];
3276 	if (test_bit(hash_32(current->pid, ilog2(BITS_PER_LONG)), &pids))
3277 		return true;
3278 
3279 	/*
3280 	 * Complete a scan that has already started regardless of PID access, or
3281 	 * some VMAs may never be scanned in multi-threaded applications:
3282 	 */
3283 	if (mm->numa_scan_offset > vma->vm_start) {
3284 		trace_sched_skip_vma_numa(mm, vma, NUMAB_SKIP_IGNORE_PID);
3285 		return true;
3286 	}
3287 
3288 	/*
3289 	 * This vma has not been accessed for a while, and if the number
3290 	 * the threads in the same process is low, which means no other
3291 	 * threads can help scan this vma, force a vma scan.
3292 	 */
3293 	if (READ_ONCE(mm->numa_scan_seq) >
3294 	   (vma->numab_state->prev_scan_seq + get_nr_threads(current)))
3295 		return true;
3296 
3297 	return false;
3298 }
3299 
3300 #define VMA_PID_RESET_PERIOD (4 * sysctl_numa_balancing_scan_delay)
3301 
3302 /*
3303  * The expensive part of numa migration is done from task_work context.
3304  * Triggered from task_tick_numa().
3305  */
3306 static void task_numa_work(struct callback_head *work)
3307 {
3308 	unsigned long migrate, next_scan, now = jiffies;
3309 	struct task_struct *p = current;
3310 	struct mm_struct *mm = p->mm;
3311 	u64 runtime = p->se.sum_exec_runtime;
3312 	struct vm_area_struct *vma;
3313 	unsigned long start, end;
3314 	unsigned long nr_pte_updates = 0;
3315 	long pages, virtpages;
3316 	struct vma_iterator vmi;
3317 	bool vma_pids_skipped;
3318 	bool vma_pids_forced = false;
3319 
3320 	WARN_ON_ONCE(p != container_of(work, struct task_struct, numa_work));
3321 
3322 	work->next = work;
3323 	/*
3324 	 * Who cares about NUMA placement when they're dying.
3325 	 *
3326 	 * NOTE: make sure not to dereference p->mm before this check,
3327 	 * exit_task_work() happens _after_ exit_mm() so we could be called
3328 	 * without p->mm even though we still had it when we enqueued this
3329 	 * work.
3330 	 */
3331 	if (p->flags & PF_EXITING)
3332 		return;
3333 
3334 	/*
3335 	 * Memory is pinned to only one NUMA node via cpuset.mems, naturally
3336 	 * no page can be migrated.
3337 	 */
3338 	if (cpusets_enabled() && nodes_weight(cpuset_current_mems_allowed) == 1) {
3339 		trace_sched_skip_cpuset_numa(current, &cpuset_current_mems_allowed);
3340 		return;
3341 	}
3342 
3343 	if (!mm->numa_next_scan) {
3344 		mm->numa_next_scan = now +
3345 			msecs_to_jiffies(sysctl_numa_balancing_scan_delay);
3346 	}
3347 
3348 	/*
3349 	 * Enforce maximal scan/migration frequency..
3350 	 */
3351 	migrate = mm->numa_next_scan;
3352 	if (time_before(now, migrate))
3353 		return;
3354 
3355 	if (p->numa_scan_period == 0) {
3356 		p->numa_scan_period_max = task_scan_max(p);
3357 		p->numa_scan_period = task_scan_start(p);
3358 	}
3359 
3360 	next_scan = now + msecs_to_jiffies(p->numa_scan_period);
3361 	if (!try_cmpxchg(&mm->numa_next_scan, &migrate, next_scan))
3362 		return;
3363 
3364 	/*
3365 	 * Delay this task enough that another task of this mm will likely win
3366 	 * the next time around.
3367 	 */
3368 	p->node_stamp += 2 * TICK_NSEC;
3369 
3370 	pages = sysctl_numa_balancing_scan_size;
3371 	pages <<= 20 - PAGE_SHIFT; /* MB in pages */
3372 	virtpages = pages * 8;	   /* Scan up to this much virtual space */
3373 	if (!pages)
3374 		return;
3375 
3376 
3377 	if (!mmap_read_trylock(mm))
3378 		return;
3379 
3380 	/*
3381 	 * VMAs are skipped if the current PID has not trapped a fault within
3382 	 * the VMA recently. Allow scanning to be forced if there is no
3383 	 * suitable VMA remaining.
3384 	 */
3385 	vma_pids_skipped = false;
3386 
3387 retry_pids:
3388 	start = mm->numa_scan_offset;
3389 	vma_iter_init(&vmi, mm, start);
3390 	vma = vma_next(&vmi);
3391 	if (!vma) {
3392 		reset_ptenuma_scan(p);
3393 		start = 0;
3394 		vma_iter_set(&vmi, start);
3395 		vma = vma_next(&vmi);
3396 	}
3397 
3398 	for (; vma; vma = vma_next(&vmi)) {
3399 		if (!vma_migratable(vma) || !vma_policy_mof(vma) ||
3400 			is_vm_hugetlb_page(vma) || (vma->vm_flags & VM_MIXEDMAP)) {
3401 			trace_sched_skip_vma_numa(mm, vma, NUMAB_SKIP_UNSUITABLE);
3402 			continue;
3403 		}
3404 
3405 		/*
3406 		 * Shared library pages mapped by multiple processes are not
3407 		 * migrated as it is expected they are cache replicated. Avoid
3408 		 * hinting faults in read-only file-backed mappings or the vDSO
3409 		 * as migrating the pages will be of marginal benefit.
3410 		 */
3411 		if (!vma->vm_mm ||
3412 		    (vma->vm_file && (vma->vm_flags & (VM_READ|VM_WRITE)) == (VM_READ))) {
3413 			trace_sched_skip_vma_numa(mm, vma, NUMAB_SKIP_SHARED_RO);
3414 			continue;
3415 		}
3416 
3417 		/*
3418 		 * Skip inaccessible VMAs to avoid any confusion between
3419 		 * PROT_NONE and NUMA hinting PTEs
3420 		 */
3421 		if (!vma_is_accessible(vma)) {
3422 			trace_sched_skip_vma_numa(mm, vma, NUMAB_SKIP_INACCESSIBLE);
3423 			continue;
3424 		}
3425 
3426 		/* Initialise new per-VMA NUMAB state. */
3427 		if (!vma->numab_state) {
3428 			struct vma_numab_state *ptr;
3429 
3430 			ptr = kzalloc(sizeof(*ptr), GFP_KERNEL);
3431 			if (!ptr)
3432 				continue;
3433 
3434 			if (cmpxchg(&vma->numab_state, NULL, ptr)) {
3435 				kfree(ptr);
3436 				continue;
3437 			}
3438 
3439 			vma->numab_state->start_scan_seq = mm->numa_scan_seq;
3440 
3441 			vma->numab_state->next_scan = now +
3442 				msecs_to_jiffies(sysctl_numa_balancing_scan_delay);
3443 
3444 			/* Reset happens after 4 times scan delay of scan start */
3445 			vma->numab_state->pids_active_reset =  vma->numab_state->next_scan +
3446 				msecs_to_jiffies(VMA_PID_RESET_PERIOD);
3447 
3448 			/*
3449 			 * Ensure prev_scan_seq does not match numa_scan_seq,
3450 			 * to prevent VMAs being skipped prematurely on the
3451 			 * first scan:
3452 			 */
3453 			 vma->numab_state->prev_scan_seq = mm->numa_scan_seq - 1;
3454 		}
3455 
3456 		/*
3457 		 * Scanning the VMAs of short lived tasks add more overhead. So
3458 		 * delay the scan for new VMAs.
3459 		 */
3460 		if (mm->numa_scan_seq && time_before(jiffies,
3461 						vma->numab_state->next_scan)) {
3462 			trace_sched_skip_vma_numa(mm, vma, NUMAB_SKIP_SCAN_DELAY);
3463 			continue;
3464 		}
3465 
3466 		/* RESET access PIDs regularly for old VMAs. */
3467 		if (mm->numa_scan_seq &&
3468 				time_after(jiffies, vma->numab_state->pids_active_reset)) {
3469 			vma->numab_state->pids_active_reset = vma->numab_state->pids_active_reset +
3470 				msecs_to_jiffies(VMA_PID_RESET_PERIOD);
3471 			vma->numab_state->pids_active[0] = READ_ONCE(vma->numab_state->pids_active[1]);
3472 			vma->numab_state->pids_active[1] = 0;
3473 		}
3474 
3475 		/* Do not rescan VMAs twice within the same sequence. */
3476 		if (vma->numab_state->prev_scan_seq == mm->numa_scan_seq) {
3477 			mm->numa_scan_offset = vma->vm_end;
3478 			trace_sched_skip_vma_numa(mm, vma, NUMAB_SKIP_SEQ_COMPLETED);
3479 			continue;
3480 		}
3481 
3482 		/*
3483 		 * Do not scan the VMA if task has not accessed it, unless no other
3484 		 * VMA candidate exists.
3485 		 */
3486 		if (!vma_pids_forced && !vma_is_accessed(mm, vma)) {
3487 			vma_pids_skipped = true;
3488 			trace_sched_skip_vma_numa(mm, vma, NUMAB_SKIP_PID_INACTIVE);
3489 			continue;
3490 		}
3491 
3492 		do {
3493 			start = max(start, vma->vm_start);
3494 			end = ALIGN(start + (pages << PAGE_SHIFT), HPAGE_SIZE);
3495 			end = min(end, vma->vm_end);
3496 			nr_pte_updates = change_prot_numa(vma, start, end);
3497 
3498 			/*
3499 			 * Try to scan sysctl_numa_balancing_size worth of
3500 			 * hpages that have at least one present PTE that
3501 			 * is not already PTE-numa. If the VMA contains
3502 			 * areas that are unused or already full of prot_numa
3503 			 * PTEs, scan up to virtpages, to skip through those
3504 			 * areas faster.
3505 			 */
3506 			if (nr_pte_updates)
3507 				pages -= (end - start) >> PAGE_SHIFT;
3508 			virtpages -= (end - start) >> PAGE_SHIFT;
3509 
3510 			start = end;
3511 			if (pages <= 0 || virtpages <= 0)
3512 				goto out;
3513 
3514 			cond_resched();
3515 		} while (end != vma->vm_end);
3516 
3517 		/* VMA scan is complete, do not scan until next sequence. */
3518 		vma->numab_state->prev_scan_seq = mm->numa_scan_seq;
3519 
3520 		/*
3521 		 * Only force scan within one VMA at a time, to limit the
3522 		 * cost of scanning a potentially uninteresting VMA.
3523 		 */
3524 		if (vma_pids_forced)
3525 			break;
3526 	}
3527 
3528 	/*
3529 	 * If no VMAs are remaining and VMAs were skipped due to the PID
3530 	 * not accessing the VMA previously, then force a scan to ensure
3531 	 * forward progress:
3532 	 */
3533 	if (!vma && !vma_pids_forced && vma_pids_skipped) {
3534 		vma_pids_forced = true;
3535 		goto retry_pids;
3536 	}
3537 
3538 out:
3539 	/*
3540 	 * It is possible to reach the end of the VMA list but the last few
3541 	 * VMAs are not guaranteed to the vma_migratable. If they are not, we
3542 	 * would find the !migratable VMA on the next scan but not reset the
3543 	 * scanner to the start so check it now.
3544 	 */
3545 	if (vma)
3546 		mm->numa_scan_offset = start;
3547 	else
3548 		reset_ptenuma_scan(p);
3549 	mmap_read_unlock(mm);
3550 
3551 	/*
3552 	 * Make sure tasks use at least 32x as much time to run other code
3553 	 * than they used here, to limit NUMA PTE scanning overhead to 3% max.
3554 	 * Usually update_task_scan_period slows down scanning enough; on an
3555 	 * overloaded system we need to limit overhead on a per task basis.
3556 	 */
3557 	if (unlikely(p->se.sum_exec_runtime != runtime)) {
3558 		u64 diff = p->se.sum_exec_runtime - runtime;
3559 		p->node_stamp += 32 * diff;
3560 	}
3561 }
3562 
3563 void init_numa_balancing(u64 clone_flags, struct task_struct *p)
3564 {
3565 	int mm_users = 0;
3566 	struct mm_struct *mm = p->mm;
3567 
3568 	if (mm) {
3569 		mm_users = atomic_read(&mm->mm_users);
3570 		if (mm_users == 1) {
3571 			mm->numa_next_scan = jiffies + msecs_to_jiffies(sysctl_numa_balancing_scan_delay);
3572 			mm->numa_scan_seq = 0;
3573 		}
3574 	}
3575 	p->node_stamp			= 0;
3576 	p->numa_scan_seq		= mm ? mm->numa_scan_seq : 0;
3577 	p->numa_scan_period		= sysctl_numa_balancing_scan_delay;
3578 	p->numa_migrate_retry		= 0;
3579 	/* Protect against double add, see task_tick_numa and task_numa_work */
3580 	p->numa_work.next		= &p->numa_work;
3581 	p->numa_faults			= NULL;
3582 	p->numa_pages_migrated		= 0;
3583 	p->total_numa_faults		= 0;
3584 	RCU_INIT_POINTER(p->numa_group, NULL);
3585 	p->last_task_numa_placement	= 0;
3586 	p->last_sum_exec_runtime	= 0;
3587 
3588 	init_task_work(&p->numa_work, task_numa_work);
3589 
3590 	/* New address space, reset the preferred nid */
3591 	if (!(clone_flags & CLONE_VM)) {
3592 		p->numa_preferred_nid = NUMA_NO_NODE;
3593 		return;
3594 	}
3595 
3596 	/*
3597 	 * New thread, keep existing numa_preferred_nid which should be copied
3598 	 * already by arch_dup_task_struct but stagger when scans start.
3599 	 */
3600 	if (mm) {
3601 		unsigned int delay;
3602 
3603 		delay = min_t(unsigned int, task_scan_max(current),
3604 			current->numa_scan_period * mm_users * NSEC_PER_MSEC);
3605 		delay += 2 * TICK_NSEC;
3606 		p->node_stamp = delay;
3607 	}
3608 }
3609 
3610 /*
3611  * Drive the periodic memory faults..
3612  */
3613 static void task_tick_numa(struct rq *rq, struct task_struct *curr)
3614 {
3615 	struct callback_head *work = &curr->numa_work;
3616 	u64 period, now;
3617 
3618 	/*
3619 	 * We don't care about NUMA placement if we don't have memory.
3620 	 */
3621 	if (!curr->mm || (curr->flags & (PF_EXITING | PF_KTHREAD)) || work->next != work)
3622 		return;
3623 
3624 	/*
3625 	 * Using runtime rather than walltime has the dual advantage that
3626 	 * we (mostly) drive the selection from busy threads and that the
3627 	 * task needs to have done some actual work before we bother with
3628 	 * NUMA placement.
3629 	 */
3630 	now = curr->se.sum_exec_runtime;
3631 	period = (u64)curr->numa_scan_period * NSEC_PER_MSEC;
3632 
3633 	if (now > curr->node_stamp + period) {
3634 		if (!curr->node_stamp)
3635 			curr->numa_scan_period = task_scan_start(curr);
3636 		curr->node_stamp += period;
3637 
3638 		if (!time_before(jiffies, curr->mm->numa_next_scan))
3639 			task_work_add(curr, work, TWA_RESUME);
3640 	}
3641 }
3642 
3643 static void update_scan_period(struct task_struct *p, int new_cpu)
3644 {
3645 	int src_nid = cpu_to_node(task_cpu(p));
3646 	int dst_nid = cpu_to_node(new_cpu);
3647 
3648 	if (!static_branch_likely(&sched_numa_balancing))
3649 		return;
3650 
3651 	if (!p->mm || !p->numa_faults || (p->flags & PF_EXITING))
3652 		return;
3653 
3654 	if (src_nid == dst_nid)
3655 		return;
3656 
3657 	/*
3658 	 * Allow resets if faults have been trapped before one scan
3659 	 * has completed. This is most likely due to a new task that
3660 	 * is pulled cross-node due to wakeups or load balancing.
3661 	 */
3662 	if (p->numa_scan_seq) {
3663 		/*
3664 		 * Avoid scan adjustments if moving to the preferred
3665 		 * node or if the task was not previously running on
3666 		 * the preferred node.
3667 		 */
3668 		if (dst_nid == p->numa_preferred_nid ||
3669 		    (p->numa_preferred_nid != NUMA_NO_NODE &&
3670 			src_nid != p->numa_preferred_nid))
3671 			return;
3672 	}
3673 
3674 	p->numa_scan_period = task_scan_start(p);
3675 }
3676 
3677 #else /* !CONFIG_NUMA_BALANCING: */
3678 
3679 static void task_tick_numa(struct rq *rq, struct task_struct *curr)
3680 {
3681 }
3682 
3683 static inline void account_numa_enqueue(struct rq *rq, struct task_struct *p)
3684 {
3685 }
3686 
3687 static inline void account_numa_dequeue(struct rq *rq, struct task_struct *p)
3688 {
3689 }
3690 
3691 static inline void update_scan_period(struct task_struct *p, int new_cpu)
3692 {
3693 }
3694 
3695 #endif /* !CONFIG_NUMA_BALANCING */
3696 
3697 static void
3698 account_entity_enqueue(struct cfs_rq *cfs_rq, struct sched_entity *se)
3699 {
3700 	update_load_add(&cfs_rq->load, se->load.weight);
3701 	if (entity_is_task(se)) {
3702 		struct rq *rq = rq_of(cfs_rq);
3703 
3704 		account_numa_enqueue(rq, task_of(se));
3705 		list_add(&se->group_node, &rq->cfs_tasks);
3706 	}
3707 	cfs_rq->nr_queued++;
3708 }
3709 
3710 static void
3711 account_entity_dequeue(struct cfs_rq *cfs_rq, struct sched_entity *se)
3712 {
3713 	update_load_sub(&cfs_rq->load, se->load.weight);
3714 	if (entity_is_task(se)) {
3715 		account_numa_dequeue(rq_of(cfs_rq), task_of(se));
3716 		list_del_init(&se->group_node);
3717 	}
3718 	cfs_rq->nr_queued--;
3719 }
3720 
3721 /*
3722  * Signed add and clamp on underflow.
3723  *
3724  * Explicitly do a load-store to ensure the intermediate value never hits
3725  * memory. This allows lockless observations without ever seeing the negative
3726  * values.
3727  */
3728 #define add_positive(_ptr, _val) do {                           \
3729 	typeof(_ptr) ptr = (_ptr);                              \
3730 	__signed_scalar_typeof(*ptr) val = (_val);              \
3731 	typeof(*ptr) res, var = READ_ONCE(*ptr);                \
3732 								\
3733 	res = var + val;                                        \
3734 								\
3735 	if (val < 0 && res > var)                               \
3736 		res = 0;                                        \
3737 								\
3738 	WRITE_ONCE(*ptr, res);                                  \
3739 } while (0)
3740 
3741 /*
3742  * Remove and clamp on negative, from a local variable.
3743  *
3744  * A variant of sub_positive(), which does not use explicit load-store
3745  * and is thus optimized for local variable updates.
3746  */
3747 #define lsub_positive(_ptr, _val) do {				\
3748 	typeof(_ptr) ptr = (_ptr);				\
3749 	*ptr -= min_t(typeof(*ptr), *ptr, _val);		\
3750 } while (0)
3751 
3752 
3753 /*
3754  * Because of rounding, se->util_sum might ends up being +1 more than
3755  * cfs->util_sum. Although this is not a problem by itself, detaching
3756  * a lot of tasks with the rounding problem between 2 updates of
3757  * util_avg (~1ms) can make cfs->util_sum becoming null whereas
3758  * cfs_util_avg is not.
3759  *
3760  * Check that util_sum is still above its lower bound for the new
3761  * util_avg. Given that period_contrib might have moved since the last
3762  * sync, we are only sure that util_sum must be above or equal to
3763  *    util_avg * minimum possible divider
3764  */
3765 #define __update_sa(sa, name, delta_avg, delta_sum) do {	\
3766 	add_positive(&(sa)->name##_avg, delta_avg);		\
3767 	add_positive(&(sa)->name##_sum, delta_sum);		\
3768 	(sa)->name##_sum = max_t(typeof((sa)->name##_sum),	\
3769 			       (sa)->name##_sum,		\
3770 			       (sa)->name##_avg * PELT_MIN_DIVIDER); \
3771 } while (0)
3772 
3773 static inline void
3774 enqueue_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se)
3775 {
3776 	__update_sa(&cfs_rq->avg, load, se->avg.load_avg,
3777 		    se_weight(se) * se->avg.load_sum);
3778 }
3779 
3780 static inline void
3781 dequeue_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se)
3782 {
3783 	__update_sa(&cfs_rq->avg, load, -se->avg.load_avg,
3784 		    se_weight(se) * -se->avg.load_sum);
3785 }
3786 
3787 static void place_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags);
3788 
3789 static void reweight_entity(struct cfs_rq *cfs_rq, struct sched_entity *se,
3790 			    unsigned long weight)
3791 {
3792 	bool curr = cfs_rq->curr == se;
3793 
3794 	if (se->on_rq) {
3795 		/* commit outstanding execution time */
3796 		update_curr(cfs_rq);
3797 		update_entity_lag(cfs_rq, se);
3798 		se->deadline -= se->vruntime;
3799 		se->rel_deadline = 1;
3800 		cfs_rq->nr_queued--;
3801 		if (!curr)
3802 			__dequeue_entity(cfs_rq, se);
3803 		update_load_sub(&cfs_rq->load, se->load.weight);
3804 	}
3805 	dequeue_load_avg(cfs_rq, se);
3806 
3807 	/*
3808 	 * Because we keep se->vlag = V - v_i, while: lag_i = w_i*(V - v_i),
3809 	 * we need to scale se->vlag when w_i changes.
3810 	 */
3811 	se->vlag = div_s64(se->vlag * se->load.weight, weight);
3812 	if (se->rel_deadline)
3813 		se->deadline = div_s64(se->deadline * se->load.weight, weight);
3814 
3815 	update_load_set(&se->load, weight);
3816 
3817 	do {
3818 		u32 divider = get_pelt_divider(&se->avg);
3819 
3820 		se->avg.load_avg = div_u64(se_weight(se) * se->avg.load_sum, divider);
3821 	} while (0);
3822 
3823 	enqueue_load_avg(cfs_rq, se);
3824 	if (se->on_rq) {
3825 		place_entity(cfs_rq, se, 0);
3826 		update_load_add(&cfs_rq->load, se->load.weight);
3827 		if (!curr)
3828 			__enqueue_entity(cfs_rq, se);
3829 		cfs_rq->nr_queued++;
3830 	}
3831 }
3832 
3833 static void reweight_task_fair(struct rq *rq, struct task_struct *p,
3834 			       const struct load_weight *lw)
3835 {
3836 	struct sched_entity *se = &p->se;
3837 	struct cfs_rq *cfs_rq = cfs_rq_of(se);
3838 	struct load_weight *load = &se->load;
3839 
3840 	reweight_entity(cfs_rq, se, lw->weight);
3841 	load->inv_weight = lw->inv_weight;
3842 }
3843 
3844 static inline int throttled_hierarchy(struct cfs_rq *cfs_rq);
3845 
3846 #ifdef CONFIG_FAIR_GROUP_SCHED
3847 /*
3848  * All this does is approximate the hierarchical proportion which includes that
3849  * global sum we all love to hate.
3850  *
3851  * That is, the weight of a group entity, is the proportional share of the
3852  * group weight based on the group runqueue weights. That is:
3853  *
3854  *                     tg->weight * grq->load.weight
3855  *   ge->load.weight = -----------------------------               (1)
3856  *                       \Sum grq->load.weight
3857  *
3858  * Now, because computing that sum is prohibitively expensive to compute (been
3859  * there, done that) we approximate it with this average stuff. The average
3860  * moves slower and therefore the approximation is cheaper and more stable.
3861  *
3862  * So instead of the above, we substitute:
3863  *
3864  *   grq->load.weight -> grq->avg.load_avg                         (2)
3865  *
3866  * which yields the following:
3867  *
3868  *                     tg->weight * grq->avg.load_avg
3869  *   ge->load.weight = ------------------------------              (3)
3870  *                             tg->load_avg
3871  *
3872  * Where: tg->load_avg ~= \Sum grq->avg.load_avg
3873  *
3874  * That is shares_avg, and it is right (given the approximation (2)).
3875  *
3876  * The problem with it is that because the average is slow -- it was designed
3877  * to be exactly that of course -- this leads to transients in boundary
3878  * conditions. In specific, the case where the group was idle and we start the
3879  * one task. It takes time for our CPU's grq->avg.load_avg to build up,
3880  * yielding bad latency etc..
3881  *
3882  * Now, in that special case (1) reduces to:
3883  *
3884  *                     tg->weight * grq->load.weight
3885  *   ge->load.weight = ----------------------------- = tg->weight   (4)
3886  *                         grp->load.weight
3887  *
3888  * That is, the sum collapses because all other CPUs are idle; the UP scenario.
3889  *
3890  * So what we do is modify our approximation (3) to approach (4) in the (near)
3891  * UP case, like:
3892  *
3893  *   ge->load.weight =
3894  *
3895  *              tg->weight * grq->load.weight
3896  *     ---------------------------------------------------         (5)
3897  *     tg->load_avg - grq->avg.load_avg + grq->load.weight
3898  *
3899  * But because grq->load.weight can drop to 0, resulting in a divide by zero,
3900  * we need to use grq->avg.load_avg as its lower bound, which then gives:
3901  *
3902  *
3903  *                     tg->weight * grq->load.weight
3904  *   ge->load.weight = -----------------------------		   (6)
3905  *                             tg_load_avg'
3906  *
3907  * Where:
3908  *
3909  *   tg_load_avg' = tg->load_avg - grq->avg.load_avg +
3910  *                  max(grq->load.weight, grq->avg.load_avg)
3911  *
3912  * And that is shares_weight and is icky. In the (near) UP case it approaches
3913  * (4) while in the normal case it approaches (3). It consistently
3914  * overestimates the ge->load.weight and therefore:
3915  *
3916  *   \Sum ge->load.weight >= tg->weight
3917  *
3918  * hence icky!
3919  */
3920 static long calc_group_shares(struct cfs_rq *cfs_rq)
3921 {
3922 	long tg_weight, tg_shares, load, shares;
3923 	struct task_group *tg = cfs_rq->tg;
3924 
3925 	tg_shares = READ_ONCE(tg->shares);
3926 
3927 	load = max(scale_load_down(cfs_rq->load.weight), cfs_rq->avg.load_avg);
3928 
3929 	tg_weight = atomic_long_read(&tg->load_avg);
3930 
3931 	/* Ensure tg_weight >= load */
3932 	tg_weight -= cfs_rq->tg_load_avg_contrib;
3933 	tg_weight += load;
3934 
3935 	shares = (tg_shares * load);
3936 	if (tg_weight)
3937 		shares /= tg_weight;
3938 
3939 	/*
3940 	 * MIN_SHARES has to be unscaled here to support per-CPU partitioning
3941 	 * of a group with small tg->shares value. It is a floor value which is
3942 	 * assigned as a minimum load.weight to the sched_entity representing
3943 	 * the group on a CPU.
3944 	 *
3945 	 * E.g. on 64-bit for a group with tg->shares of scale_load(15)=15*1024
3946 	 * on an 8-core system with 8 tasks each runnable on one CPU shares has
3947 	 * to be 15*1024*1/8=1920 instead of scale_load(MIN_SHARES)=2*1024. In
3948 	 * case no task is runnable on a CPU MIN_SHARES=2 should be returned
3949 	 * instead of 0.
3950 	 */
3951 	return clamp_t(long, shares, MIN_SHARES, tg_shares);
3952 }
3953 
3954 /*
3955  * Recomputes the group entity based on the current state of its group
3956  * runqueue.
3957  */
3958 static void update_cfs_group(struct sched_entity *se)
3959 {
3960 	struct cfs_rq *gcfs_rq = group_cfs_rq(se);
3961 	long shares;
3962 
3963 	/*
3964 	 * When a group becomes empty, preserve its weight. This matters for
3965 	 * DELAY_DEQUEUE.
3966 	 */
3967 	if (!gcfs_rq || !gcfs_rq->load.weight)
3968 		return;
3969 
3970 	shares = calc_group_shares(gcfs_rq);
3971 	if (unlikely(se->load.weight != shares))
3972 		reweight_entity(cfs_rq_of(se), se, shares);
3973 }
3974 
3975 #else /* !CONFIG_FAIR_GROUP_SCHED: */
3976 static inline void update_cfs_group(struct sched_entity *se)
3977 {
3978 }
3979 #endif /* !CONFIG_FAIR_GROUP_SCHED */
3980 
3981 static inline void cfs_rq_util_change(struct cfs_rq *cfs_rq, int flags)
3982 {
3983 	struct rq *rq = rq_of(cfs_rq);
3984 
3985 	if (&rq->cfs == cfs_rq) {
3986 		/*
3987 		 * There are a few boundary cases this might miss but it should
3988 		 * get called often enough that that should (hopefully) not be
3989 		 * a real problem.
3990 		 *
3991 		 * It will not get called when we go idle, because the idle
3992 		 * thread is a different class (!fair), nor will the utilization
3993 		 * number include things like RT tasks.
3994 		 *
3995 		 * As is, the util number is not freq-invariant (we'd have to
3996 		 * implement arch_scale_freq_capacity() for that).
3997 		 *
3998 		 * See cpu_util_cfs().
3999 		 */
4000 		cpufreq_update_util(rq, flags);
4001 	}
4002 }
4003 
4004 static inline bool load_avg_is_decayed(struct sched_avg *sa)
4005 {
4006 	if (sa->load_sum)
4007 		return false;
4008 
4009 	if (sa->util_sum)
4010 		return false;
4011 
4012 	if (sa->runnable_sum)
4013 		return false;
4014 
4015 	/*
4016 	 * _avg must be null when _sum are null because _avg = _sum / divider
4017 	 * Make sure that rounding and/or propagation of PELT values never
4018 	 * break this.
4019 	 */
4020 	WARN_ON_ONCE(sa->load_avg ||
4021 		      sa->util_avg ||
4022 		      sa->runnable_avg);
4023 
4024 	return true;
4025 }
4026 
4027 static inline u64 cfs_rq_last_update_time(struct cfs_rq *cfs_rq)
4028 {
4029 	return u64_u32_load_copy(cfs_rq->avg.last_update_time,
4030 				 cfs_rq->last_update_time_copy);
4031 }
4032 #ifdef CONFIG_FAIR_GROUP_SCHED
4033 /*
4034  * Because list_add_leaf_cfs_rq always places a child cfs_rq on the list
4035  * immediately before a parent cfs_rq, and cfs_rqs are removed from the list
4036  * bottom-up, we only have to test whether the cfs_rq before us on the list
4037  * is our child.
4038  * If cfs_rq is not on the list, test whether a child needs its to be added to
4039  * connect a branch to the tree  * (see list_add_leaf_cfs_rq() for details).
4040  */
4041 static inline bool child_cfs_rq_on_list(struct cfs_rq *cfs_rq)
4042 {
4043 	struct cfs_rq *prev_cfs_rq;
4044 	struct list_head *prev;
4045 	struct rq *rq = rq_of(cfs_rq);
4046 
4047 	if (cfs_rq->on_list) {
4048 		prev = cfs_rq->leaf_cfs_rq_list.prev;
4049 	} else {
4050 		prev = rq->tmp_alone_branch;
4051 	}
4052 
4053 	if (prev == &rq->leaf_cfs_rq_list)
4054 		return false;
4055 
4056 	prev_cfs_rq = container_of(prev, struct cfs_rq, leaf_cfs_rq_list);
4057 
4058 	return (prev_cfs_rq->tg->parent == cfs_rq->tg);
4059 }
4060 
4061 static inline bool cfs_rq_is_decayed(struct cfs_rq *cfs_rq)
4062 {
4063 	if (cfs_rq->load.weight)
4064 		return false;
4065 
4066 	if (!load_avg_is_decayed(&cfs_rq->avg))
4067 		return false;
4068 
4069 	if (child_cfs_rq_on_list(cfs_rq))
4070 		return false;
4071 
4072 	if (cfs_rq->tg_load_avg_contrib)
4073 		return false;
4074 
4075 	return true;
4076 }
4077 
4078 /**
4079  * update_tg_load_avg - update the tg's load avg
4080  * @cfs_rq: the cfs_rq whose avg changed
4081  *
4082  * This function 'ensures': tg->load_avg := \Sum tg->cfs_rq[]->avg.load.
4083  * However, because tg->load_avg is a global value there are performance
4084  * considerations.
4085  *
4086  * In order to avoid having to look at the other cfs_rq's, we use a
4087  * differential update where we store the last value we propagated. This in
4088  * turn allows skipping updates if the differential is 'small'.
4089  *
4090  * Updating tg's load_avg is necessary before update_cfs_share().
4091  */
4092 static inline void update_tg_load_avg(struct cfs_rq *cfs_rq)
4093 {
4094 	long delta;
4095 	u64 now;
4096 
4097 	/*
4098 	 * No need to update load_avg for root_task_group as it is not used.
4099 	 */
4100 	if (cfs_rq->tg == &root_task_group)
4101 		return;
4102 
4103 	/* rq has been offline and doesn't contribute to the share anymore: */
4104 	if (!cpu_active(cpu_of(rq_of(cfs_rq))))
4105 		return;
4106 
4107 	/*
4108 	 * For migration heavy workloads, access to tg->load_avg can be
4109 	 * unbound. Limit the update rate to at most once per ms.
4110 	 */
4111 	now = sched_clock_cpu(cpu_of(rq_of(cfs_rq)));
4112 	if (now - cfs_rq->last_update_tg_load_avg < NSEC_PER_MSEC)
4113 		return;
4114 
4115 	delta = cfs_rq->avg.load_avg - cfs_rq->tg_load_avg_contrib;
4116 	if (abs(delta) > cfs_rq->tg_load_avg_contrib / 64) {
4117 		atomic_long_add(delta, &cfs_rq->tg->load_avg);
4118 		cfs_rq->tg_load_avg_contrib = cfs_rq->avg.load_avg;
4119 		cfs_rq->last_update_tg_load_avg = now;
4120 	}
4121 }
4122 
4123 static inline void clear_tg_load_avg(struct cfs_rq *cfs_rq)
4124 {
4125 	long delta;
4126 	u64 now;
4127 
4128 	/*
4129 	 * No need to update load_avg for root_task_group, as it is not used.
4130 	 */
4131 	if (cfs_rq->tg == &root_task_group)
4132 		return;
4133 
4134 	now = sched_clock_cpu(cpu_of(rq_of(cfs_rq)));
4135 	delta = 0 - cfs_rq->tg_load_avg_contrib;
4136 	atomic_long_add(delta, &cfs_rq->tg->load_avg);
4137 	cfs_rq->tg_load_avg_contrib = 0;
4138 	cfs_rq->last_update_tg_load_avg = now;
4139 }
4140 
4141 /* CPU offline callback: */
4142 static void __maybe_unused clear_tg_offline_cfs_rqs(struct rq *rq)
4143 {
4144 	struct task_group *tg;
4145 
4146 	lockdep_assert_rq_held(rq);
4147 
4148 	/*
4149 	 * The rq clock has already been updated in
4150 	 * set_rq_offline(), so we should skip updating
4151 	 * the rq clock again in unthrottle_cfs_rq().
4152 	 */
4153 	rq_clock_start_loop_update(rq);
4154 
4155 	rcu_read_lock();
4156 	list_for_each_entry_rcu(tg, &task_groups, list) {
4157 		struct cfs_rq *cfs_rq = tg->cfs_rq[cpu_of(rq)];
4158 
4159 		clear_tg_load_avg(cfs_rq);
4160 	}
4161 	rcu_read_unlock();
4162 
4163 	rq_clock_stop_loop_update(rq);
4164 }
4165 
4166 /*
4167  * Called within set_task_rq() right before setting a task's CPU. The
4168  * caller only guarantees p->pi_lock is held; no other assumptions,
4169  * including the state of rq->lock, should be made.
4170  */
4171 void set_task_rq_fair(struct sched_entity *se,
4172 		      struct cfs_rq *prev, struct cfs_rq *next)
4173 {
4174 	u64 p_last_update_time;
4175 	u64 n_last_update_time;
4176 
4177 	if (!sched_feat(ATTACH_AGE_LOAD))
4178 		return;
4179 
4180 	/*
4181 	 * We are supposed to update the task to "current" time, then its up to
4182 	 * date and ready to go to new CPU/cfs_rq. But we have difficulty in
4183 	 * getting what current time is, so simply throw away the out-of-date
4184 	 * time. This will result in the wakee task is less decayed, but giving
4185 	 * the wakee more load sounds not bad.
4186 	 */
4187 	if (!(se->avg.last_update_time && prev))
4188 		return;
4189 
4190 	p_last_update_time = cfs_rq_last_update_time(prev);
4191 	n_last_update_time = cfs_rq_last_update_time(next);
4192 
4193 	__update_load_avg_blocked_se(p_last_update_time, se);
4194 	se->avg.last_update_time = n_last_update_time;
4195 }
4196 
4197 /*
4198  * When on migration a sched_entity joins/leaves the PELT hierarchy, we need to
4199  * propagate its contribution. The key to this propagation is the invariant
4200  * that for each group:
4201  *
4202  *   ge->avg == grq->avg						(1)
4203  *
4204  * _IFF_ we look at the pure running and runnable sums. Because they
4205  * represent the very same entity, just at different points in the hierarchy.
4206  *
4207  * Per the above update_tg_cfs_util() and update_tg_cfs_runnable() are trivial
4208  * and simply copies the running/runnable sum over (but still wrong, because
4209  * the group entity and group rq do not have their PELT windows aligned).
4210  *
4211  * However, update_tg_cfs_load() is more complex. So we have:
4212  *
4213  *   ge->avg.load_avg = ge->load.weight * ge->avg.runnable_avg		(2)
4214  *
4215  * And since, like util, the runnable part should be directly transferable,
4216  * the following would _appear_ to be the straight forward approach:
4217  *
4218  *   grq->avg.load_avg = grq->load.weight * grq->avg.runnable_avg	(3)
4219  *
4220  * And per (1) we have:
4221  *
4222  *   ge->avg.runnable_avg == grq->avg.runnable_avg
4223  *
4224  * Which gives:
4225  *
4226  *                      ge->load.weight * grq->avg.load_avg
4227  *   ge->avg.load_avg = -----------------------------------		(4)
4228  *                               grq->load.weight
4229  *
4230  * Except that is wrong!
4231  *
4232  * Because while for entities historical weight is not important and we
4233  * really only care about our future and therefore can consider a pure
4234  * runnable sum, runqueues can NOT do this.
4235  *
4236  * We specifically want runqueues to have a load_avg that includes
4237  * historical weights. Those represent the blocked load, the load we expect
4238  * to (shortly) return to us. This only works by keeping the weights as
4239  * integral part of the sum. We therefore cannot decompose as per (3).
4240  *
4241  * Another reason this doesn't work is that runnable isn't a 0-sum entity.
4242  * Imagine a rq with 2 tasks that each are runnable 2/3 of the time. Then the
4243  * rq itself is runnable anywhere between 2/3 and 1 depending on how the
4244  * runnable section of these tasks overlap (or not). If they were to perfectly
4245  * align the rq as a whole would be runnable 2/3 of the time. If however we
4246  * always have at least 1 runnable task, the rq as a whole is always runnable.
4247  *
4248  * So we'll have to approximate.. :/
4249  *
4250  * Given the constraint:
4251  *
4252  *   ge->avg.running_sum <= ge->avg.runnable_sum <= LOAD_AVG_MAX
4253  *
4254  * We can construct a rule that adds runnable to a rq by assuming minimal
4255  * overlap.
4256  *
4257  * On removal, we'll assume each task is equally runnable; which yields:
4258  *
4259  *   grq->avg.runnable_sum = grq->avg.load_sum / grq->load.weight
4260  *
4261  * XXX: only do this for the part of runnable > running ?
4262  *
4263  */
4264 static inline void
4265 update_tg_cfs_util(struct cfs_rq *cfs_rq, struct sched_entity *se, struct cfs_rq *gcfs_rq)
4266 {
4267 	long delta_sum, delta_avg = gcfs_rq->avg.util_avg - se->avg.util_avg;
4268 	u32 new_sum, divider;
4269 
4270 	/* Nothing to update */
4271 	if (!delta_avg)
4272 		return;
4273 
4274 	/*
4275 	 * cfs_rq->avg.period_contrib can be used for both cfs_rq and se.
4276 	 * See ___update_load_avg() for details.
4277 	 */
4278 	divider = get_pelt_divider(&cfs_rq->avg);
4279 
4280 	/* Set new sched_entity's utilization */
4281 	se->avg.util_avg = gcfs_rq->avg.util_avg;
4282 	new_sum = se->avg.util_avg * divider;
4283 	delta_sum = (long)new_sum - (long)se->avg.util_sum;
4284 	se->avg.util_sum = new_sum;
4285 
4286 	/* Update parent cfs_rq utilization */
4287 	__update_sa(&cfs_rq->avg, util, delta_avg, delta_sum);
4288 }
4289 
4290 static inline void
4291 update_tg_cfs_runnable(struct cfs_rq *cfs_rq, struct sched_entity *se, struct cfs_rq *gcfs_rq)
4292 {
4293 	long delta_sum, delta_avg = gcfs_rq->avg.runnable_avg - se->avg.runnable_avg;
4294 	u32 new_sum, divider;
4295 
4296 	/* Nothing to update */
4297 	if (!delta_avg)
4298 		return;
4299 
4300 	/*
4301 	 * cfs_rq->avg.period_contrib can be used for both cfs_rq and se.
4302 	 * See ___update_load_avg() for details.
4303 	 */
4304 	divider = get_pelt_divider(&cfs_rq->avg);
4305 
4306 	/* Set new sched_entity's runnable */
4307 	se->avg.runnable_avg = gcfs_rq->avg.runnable_avg;
4308 	new_sum = se->avg.runnable_avg * divider;
4309 	delta_sum = (long)new_sum - (long)se->avg.runnable_sum;
4310 	se->avg.runnable_sum = new_sum;
4311 
4312 	/* Update parent cfs_rq runnable */
4313 	__update_sa(&cfs_rq->avg, runnable, delta_avg, delta_sum);
4314 }
4315 
4316 static inline void
4317 update_tg_cfs_load(struct cfs_rq *cfs_rq, struct sched_entity *se, struct cfs_rq *gcfs_rq)
4318 {
4319 	long delta_avg, running_sum, runnable_sum = gcfs_rq->prop_runnable_sum;
4320 	unsigned long load_avg;
4321 	u64 load_sum = 0;
4322 	s64 delta_sum;
4323 	u32 divider;
4324 
4325 	if (!runnable_sum)
4326 		return;
4327 
4328 	gcfs_rq->prop_runnable_sum = 0;
4329 
4330 	/*
4331 	 * cfs_rq->avg.period_contrib can be used for both cfs_rq and se.
4332 	 * See ___update_load_avg() for details.
4333 	 */
4334 	divider = get_pelt_divider(&cfs_rq->avg);
4335 
4336 	if (runnable_sum >= 0) {
4337 		/*
4338 		 * Add runnable; clip at LOAD_AVG_MAX. Reflects that until
4339 		 * the CPU is saturated running == runnable.
4340 		 */
4341 		runnable_sum += se->avg.load_sum;
4342 		runnable_sum = min_t(long, runnable_sum, divider);
4343 	} else {
4344 		/*
4345 		 * Estimate the new unweighted runnable_sum of the gcfs_rq by
4346 		 * assuming all tasks are equally runnable.
4347 		 */
4348 		if (scale_load_down(gcfs_rq->load.weight)) {
4349 			load_sum = div_u64(gcfs_rq->avg.load_sum,
4350 				scale_load_down(gcfs_rq->load.weight));
4351 		}
4352 
4353 		/* But make sure to not inflate se's runnable */
4354 		runnable_sum = min(se->avg.load_sum, load_sum);
4355 	}
4356 
4357 	/*
4358 	 * runnable_sum can't be lower than running_sum
4359 	 * Rescale running sum to be in the same range as runnable sum
4360 	 * running_sum is in [0 : LOAD_AVG_MAX <<  SCHED_CAPACITY_SHIFT]
4361 	 * runnable_sum is in [0 : LOAD_AVG_MAX]
4362 	 */
4363 	running_sum = se->avg.util_sum >> SCHED_CAPACITY_SHIFT;
4364 	runnable_sum = max(runnable_sum, running_sum);
4365 
4366 	load_sum = se_weight(se) * runnable_sum;
4367 	load_avg = div_u64(load_sum, divider);
4368 
4369 	delta_avg = load_avg - se->avg.load_avg;
4370 	if (!delta_avg)
4371 		return;
4372 
4373 	delta_sum = load_sum - (s64)se_weight(se) * se->avg.load_sum;
4374 
4375 	se->avg.load_sum = runnable_sum;
4376 	se->avg.load_avg = load_avg;
4377 	__update_sa(&cfs_rq->avg, load, delta_avg, delta_sum);
4378 }
4379 
4380 static inline void add_tg_cfs_propagate(struct cfs_rq *cfs_rq, long runnable_sum)
4381 {
4382 	cfs_rq->propagate = 1;
4383 	cfs_rq->prop_runnable_sum += runnable_sum;
4384 }
4385 
4386 /* Update task and its cfs_rq load average */
4387 static inline int propagate_entity_load_avg(struct sched_entity *se)
4388 {
4389 	struct cfs_rq *cfs_rq, *gcfs_rq;
4390 
4391 	if (entity_is_task(se))
4392 		return 0;
4393 
4394 	gcfs_rq = group_cfs_rq(se);
4395 	if (!gcfs_rq->propagate)
4396 		return 0;
4397 
4398 	gcfs_rq->propagate = 0;
4399 
4400 	cfs_rq = cfs_rq_of(se);
4401 
4402 	add_tg_cfs_propagate(cfs_rq, gcfs_rq->prop_runnable_sum);
4403 
4404 	update_tg_cfs_util(cfs_rq, se, gcfs_rq);
4405 	update_tg_cfs_runnable(cfs_rq, se, gcfs_rq);
4406 	update_tg_cfs_load(cfs_rq, se, gcfs_rq);
4407 
4408 	trace_pelt_cfs_tp(cfs_rq);
4409 	trace_pelt_se_tp(se);
4410 
4411 	return 1;
4412 }
4413 
4414 /*
4415  * Check if we need to update the load and the utilization of a blocked
4416  * group_entity:
4417  */
4418 static inline bool skip_blocked_update(struct sched_entity *se)
4419 {
4420 	struct cfs_rq *gcfs_rq = group_cfs_rq(se);
4421 
4422 	/*
4423 	 * If sched_entity still have not zero load or utilization, we have to
4424 	 * decay it:
4425 	 */
4426 	if (se->avg.load_avg || se->avg.util_avg)
4427 		return false;
4428 
4429 	/*
4430 	 * If there is a pending propagation, we have to update the load and
4431 	 * the utilization of the sched_entity:
4432 	 */
4433 	if (gcfs_rq->propagate)
4434 		return false;
4435 
4436 	/*
4437 	 * Otherwise, the load and the utilization of the sched_entity is
4438 	 * already zero and there is no pending propagation, so it will be a
4439 	 * waste of time to try to decay it:
4440 	 */
4441 	return true;
4442 }
4443 
4444 #else /* !CONFIG_FAIR_GROUP_SCHED: */
4445 
4446 static inline void update_tg_load_avg(struct cfs_rq *cfs_rq) {}
4447 
4448 static inline void clear_tg_offline_cfs_rqs(struct rq *rq) {}
4449 
4450 static inline int propagate_entity_load_avg(struct sched_entity *se)
4451 {
4452 	return 0;
4453 }
4454 
4455 static inline void add_tg_cfs_propagate(struct cfs_rq *cfs_rq, long runnable_sum) {}
4456 
4457 #endif /* !CONFIG_FAIR_GROUP_SCHED */
4458 
4459 #ifdef CONFIG_NO_HZ_COMMON
4460 static inline void migrate_se_pelt_lag(struct sched_entity *se)
4461 {
4462 	u64 throttled = 0, now, lut;
4463 	struct cfs_rq *cfs_rq;
4464 	struct rq *rq;
4465 	bool is_idle;
4466 
4467 	if (load_avg_is_decayed(&se->avg))
4468 		return;
4469 
4470 	cfs_rq = cfs_rq_of(se);
4471 	rq = rq_of(cfs_rq);
4472 
4473 	rcu_read_lock();
4474 	is_idle = is_idle_task(rcu_dereference_all(rq->curr));
4475 	rcu_read_unlock();
4476 
4477 	/*
4478 	 * The lag estimation comes with a cost we don't want to pay all the
4479 	 * time. Hence, limiting to the case where the source CPU is idle and
4480 	 * we know we are at the greatest risk to have an outdated clock.
4481 	 */
4482 	if (!is_idle)
4483 		return;
4484 
4485 	/*
4486 	 * Estimated "now" is: last_update_time + cfs_idle_lag + rq_idle_lag, where:
4487 	 *
4488 	 *   last_update_time (the cfs_rq's last_update_time)
4489 	 *	= cfs_rq_clock_pelt()@cfs_rq_idle
4490 	 *      = rq_clock_pelt()@cfs_rq_idle
4491 	 *        - cfs->throttled_clock_pelt_time@cfs_rq_idle
4492 	 *
4493 	 *   cfs_idle_lag (delta between rq's update and cfs_rq's update)
4494 	 *      = rq_clock_pelt()@rq_idle - rq_clock_pelt()@cfs_rq_idle
4495 	 *
4496 	 *   rq_idle_lag (delta between now and rq's update)
4497 	 *      = sched_clock_cpu() - rq_clock()@rq_idle
4498 	 *
4499 	 * We can then write:
4500 	 *
4501 	 *    now = rq_clock_pelt()@rq_idle - cfs->throttled_clock_pelt_time +
4502 	 *          sched_clock_cpu() - rq_clock()@rq_idle
4503 	 * Where:
4504 	 *      rq_clock_pelt()@rq_idle is rq->clock_pelt_idle
4505 	 *      rq_clock()@rq_idle      is rq->clock_idle
4506 	 *      cfs->throttled_clock_pelt_time@cfs_rq_idle
4507 	 *                              is cfs_rq->throttled_pelt_idle
4508 	 */
4509 
4510 #ifdef CONFIG_CFS_BANDWIDTH
4511 	throttled = u64_u32_load(cfs_rq->throttled_pelt_idle);
4512 	/* The clock has been stopped for throttling */
4513 	if (throttled == U64_MAX)
4514 		return;
4515 #endif
4516 	now = u64_u32_load(rq->clock_pelt_idle);
4517 	/*
4518 	 * Paired with _update_idle_rq_clock_pelt(). It ensures at the worst case
4519 	 * is observed the old clock_pelt_idle value and the new clock_idle,
4520 	 * which lead to an underestimation. The opposite would lead to an
4521 	 * overestimation.
4522 	 */
4523 	smp_rmb();
4524 	lut = cfs_rq_last_update_time(cfs_rq);
4525 
4526 	now -= throttled;
4527 	if (now < lut)
4528 		/*
4529 		 * cfs_rq->avg.last_update_time is more recent than our
4530 		 * estimation, let's use it.
4531 		 */
4532 		now = lut;
4533 	else
4534 		now += sched_clock_cpu(cpu_of(rq)) - u64_u32_load(rq->clock_idle);
4535 
4536 	__update_load_avg_blocked_se(now, se);
4537 }
4538 #else /* !CONFIG_NO_HZ_COMMON: */
4539 static void migrate_se_pelt_lag(struct sched_entity *se) {}
4540 #endif /* !CONFIG_NO_HZ_COMMON */
4541 
4542 /**
4543  * update_cfs_rq_load_avg - update the cfs_rq's load/util averages
4544  * @now: current time, as per cfs_rq_clock_pelt()
4545  * @cfs_rq: cfs_rq to update
4546  *
4547  * The cfs_rq avg is the direct sum of all its entities (blocked and runnable)
4548  * avg. The immediate corollary is that all (fair) tasks must be attached.
4549  *
4550  * cfs_rq->avg is used for task_h_load() and update_cfs_share() for example.
4551  *
4552  * Return: true if the load decayed or we removed load.
4553  *
4554  * Since both these conditions indicate a changed cfs_rq->avg.load we should
4555  * call update_tg_load_avg() when this function returns true.
4556  */
4557 static inline int
4558 update_cfs_rq_load_avg(u64 now, struct cfs_rq *cfs_rq)
4559 {
4560 	unsigned long removed_load = 0, removed_util = 0, removed_runnable = 0;
4561 	struct sched_avg *sa = &cfs_rq->avg;
4562 	int decayed = 0;
4563 
4564 	if (cfs_rq->removed.nr) {
4565 		unsigned long r;
4566 		u32 divider = get_pelt_divider(&cfs_rq->avg);
4567 
4568 		raw_spin_lock(&cfs_rq->removed.lock);
4569 		swap(cfs_rq->removed.util_avg, removed_util);
4570 		swap(cfs_rq->removed.load_avg, removed_load);
4571 		swap(cfs_rq->removed.runnable_avg, removed_runnable);
4572 		cfs_rq->removed.nr = 0;
4573 		raw_spin_unlock(&cfs_rq->removed.lock);
4574 
4575 		r = removed_load;
4576 		__update_sa(sa, load, -r, -r*divider);
4577 
4578 		r = removed_util;
4579 		__update_sa(sa, util, -r, -r*divider);
4580 
4581 		r = removed_runnable;
4582 		__update_sa(sa, runnable, -r, -r*divider);
4583 
4584 		/*
4585 		 * removed_runnable is the unweighted version of removed_load so we
4586 		 * can use it to estimate removed_load_sum.
4587 		 */
4588 		add_tg_cfs_propagate(cfs_rq,
4589 			-(long)(removed_runnable * divider) >> SCHED_CAPACITY_SHIFT);
4590 
4591 		decayed = 1;
4592 	}
4593 
4594 	decayed |= __update_load_avg_cfs_rq(now, cfs_rq);
4595 	u64_u32_store_copy(sa->last_update_time,
4596 			   cfs_rq->last_update_time_copy,
4597 			   sa->last_update_time);
4598 	return decayed;
4599 }
4600 
4601 /**
4602  * attach_entity_load_avg - attach this entity to its cfs_rq load avg
4603  * @cfs_rq: cfs_rq to attach to
4604  * @se: sched_entity to attach
4605  *
4606  * Must call update_cfs_rq_load_avg() before this, since we rely on
4607  * cfs_rq->avg.last_update_time being current.
4608  */
4609 static void attach_entity_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se)
4610 {
4611 	/*
4612 	 * cfs_rq->avg.period_contrib can be used for both cfs_rq and se.
4613 	 * See ___update_load_avg() for details.
4614 	 */
4615 	u32 divider = get_pelt_divider(&cfs_rq->avg);
4616 
4617 	/*
4618 	 * When we attach the @se to the @cfs_rq, we must align the decay
4619 	 * window because without that, really weird and wonderful things can
4620 	 * happen.
4621 	 *
4622 	 * XXX illustrate
4623 	 */
4624 	se->avg.last_update_time = cfs_rq->avg.last_update_time;
4625 	se->avg.period_contrib = cfs_rq->avg.period_contrib;
4626 
4627 	/*
4628 	 * Hell(o) Nasty stuff.. we need to recompute _sum based on the new
4629 	 * period_contrib. This isn't strictly correct, but since we're
4630 	 * entirely outside of the PELT hierarchy, nobody cares if we truncate
4631 	 * _sum a little.
4632 	 */
4633 	se->avg.util_sum = se->avg.util_avg * divider;
4634 
4635 	se->avg.runnable_sum = se->avg.runnable_avg * divider;
4636 
4637 	se->avg.load_sum = se->avg.load_avg * divider;
4638 	if (se_weight(se) < se->avg.load_sum)
4639 		se->avg.load_sum = div_u64(se->avg.load_sum, se_weight(se));
4640 	else
4641 		se->avg.load_sum = 1;
4642 
4643 	enqueue_load_avg(cfs_rq, se);
4644 	cfs_rq->avg.util_avg += se->avg.util_avg;
4645 	cfs_rq->avg.util_sum += se->avg.util_sum;
4646 	cfs_rq->avg.runnable_avg += se->avg.runnable_avg;
4647 	cfs_rq->avg.runnable_sum += se->avg.runnable_sum;
4648 
4649 	add_tg_cfs_propagate(cfs_rq, se->avg.load_sum);
4650 
4651 	cfs_rq_util_change(cfs_rq, 0);
4652 
4653 	trace_pelt_cfs_tp(cfs_rq);
4654 }
4655 
4656 /**
4657  * detach_entity_load_avg - detach this entity from its cfs_rq load avg
4658  * @cfs_rq: cfs_rq to detach from
4659  * @se: sched_entity to detach
4660  *
4661  * Must call update_cfs_rq_load_avg() before this, since we rely on
4662  * cfs_rq->avg.last_update_time being current.
4663  */
4664 static void detach_entity_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se)
4665 {
4666 	dequeue_load_avg(cfs_rq, se);
4667 	__update_sa(&cfs_rq->avg, util, -se->avg.util_avg, -se->avg.util_sum);
4668 	__update_sa(&cfs_rq->avg, runnable, -se->avg.runnable_avg, -se->avg.runnable_sum);
4669 
4670 	add_tg_cfs_propagate(cfs_rq, -se->avg.load_sum);
4671 
4672 	cfs_rq_util_change(cfs_rq, 0);
4673 
4674 	trace_pelt_cfs_tp(cfs_rq);
4675 }
4676 
4677 /*
4678  * Optional action to be done while updating the load average
4679  */
4680 #define UPDATE_TG	0x1
4681 #define SKIP_AGE_LOAD	0x2
4682 #define DO_ATTACH	0x4
4683 #define DO_DETACH	0x8
4684 
4685 /* Update task and its cfs_rq load average */
4686 static inline void update_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags)
4687 {
4688 	u64 now = cfs_rq_clock_pelt(cfs_rq);
4689 	int decayed;
4690 
4691 	/*
4692 	 * Track task load average for carrying it to new CPU after migrated, and
4693 	 * track group sched_entity load average for task_h_load calculation in migration
4694 	 */
4695 	if (se->avg.last_update_time && !(flags & SKIP_AGE_LOAD))
4696 		__update_load_avg_se(now, cfs_rq, se);
4697 
4698 	decayed  = update_cfs_rq_load_avg(now, cfs_rq);
4699 	decayed |= propagate_entity_load_avg(se);
4700 
4701 	if (!se->avg.last_update_time && (flags & DO_ATTACH)) {
4702 
4703 		/*
4704 		 * DO_ATTACH means we're here from enqueue_entity().
4705 		 * !last_update_time means we've passed through
4706 		 * migrate_task_rq_fair() indicating we migrated.
4707 		 *
4708 		 * IOW we're enqueueing a task on a new CPU.
4709 		 */
4710 		attach_entity_load_avg(cfs_rq, se);
4711 		update_tg_load_avg(cfs_rq);
4712 
4713 	} else if (flags & DO_DETACH) {
4714 		/*
4715 		 * DO_DETACH means we're here from dequeue_entity()
4716 		 * and we are migrating task out of the CPU.
4717 		 */
4718 		detach_entity_load_avg(cfs_rq, se);
4719 		update_tg_load_avg(cfs_rq);
4720 	} else if (decayed) {
4721 		cfs_rq_util_change(cfs_rq, 0);
4722 
4723 		if (flags & UPDATE_TG)
4724 			update_tg_load_avg(cfs_rq);
4725 	}
4726 }
4727 
4728 /*
4729  * Synchronize entity load avg of dequeued entity without locking
4730  * the previous rq.
4731  */
4732 static void sync_entity_load_avg(struct sched_entity *se)
4733 {
4734 	struct cfs_rq *cfs_rq = cfs_rq_of(se);
4735 	u64 last_update_time;
4736 
4737 	last_update_time = cfs_rq_last_update_time(cfs_rq);
4738 	__update_load_avg_blocked_se(last_update_time, se);
4739 }
4740 
4741 /*
4742  * Task first catches up with cfs_rq, and then subtract
4743  * itself from the cfs_rq (task must be off the queue now).
4744  */
4745 static void remove_entity_load_avg(struct sched_entity *se)
4746 {
4747 	struct cfs_rq *cfs_rq = cfs_rq_of(se);
4748 	unsigned long flags;
4749 
4750 	/*
4751 	 * tasks cannot exit without having gone through wake_up_new_task() ->
4752 	 * enqueue_task_fair() which will have added things to the cfs_rq,
4753 	 * so we can remove unconditionally.
4754 	 */
4755 
4756 	sync_entity_load_avg(se);
4757 
4758 	raw_spin_lock_irqsave(&cfs_rq->removed.lock, flags);
4759 	++cfs_rq->removed.nr;
4760 	cfs_rq->removed.util_avg	+= se->avg.util_avg;
4761 	cfs_rq->removed.load_avg	+= se->avg.load_avg;
4762 	cfs_rq->removed.runnable_avg	+= se->avg.runnable_avg;
4763 	raw_spin_unlock_irqrestore(&cfs_rq->removed.lock, flags);
4764 }
4765 
4766 static inline unsigned long cfs_rq_runnable_avg(struct cfs_rq *cfs_rq)
4767 {
4768 	return cfs_rq->avg.runnable_avg;
4769 }
4770 
4771 static inline unsigned long cfs_rq_load_avg(struct cfs_rq *cfs_rq)
4772 {
4773 	return cfs_rq->avg.load_avg;
4774 }
4775 
4776 static int sched_balance_newidle(struct rq *this_rq, struct rq_flags *rf)
4777 	__must_hold(__rq_lockp(this_rq));
4778 
4779 static inline unsigned long task_util(struct task_struct *p)
4780 {
4781 	return READ_ONCE(p->se.avg.util_avg);
4782 }
4783 
4784 static inline unsigned long task_runnable(struct task_struct *p)
4785 {
4786 	return READ_ONCE(p->se.avg.runnable_avg);
4787 }
4788 
4789 static inline unsigned long _task_util_est(struct task_struct *p)
4790 {
4791 	return READ_ONCE(p->se.avg.util_est) & ~UTIL_AVG_UNCHANGED;
4792 }
4793 
4794 static inline unsigned long task_util_est(struct task_struct *p)
4795 {
4796 	return max(task_util(p), _task_util_est(p));
4797 }
4798 
4799 static inline void util_est_enqueue(struct cfs_rq *cfs_rq,
4800 				    struct task_struct *p)
4801 {
4802 	unsigned int enqueued;
4803 
4804 	if (!sched_feat(UTIL_EST))
4805 		return;
4806 
4807 	/* Update root cfs_rq's estimated utilization */
4808 	enqueued  = cfs_rq->avg.util_est;
4809 	enqueued += _task_util_est(p);
4810 	WRITE_ONCE(cfs_rq->avg.util_est, enqueued);
4811 
4812 	trace_sched_util_est_cfs_tp(cfs_rq);
4813 }
4814 
4815 static inline void util_est_dequeue(struct cfs_rq *cfs_rq,
4816 				    struct task_struct *p)
4817 {
4818 	unsigned int enqueued;
4819 
4820 	if (!sched_feat(UTIL_EST))
4821 		return;
4822 
4823 	/* Update root cfs_rq's estimated utilization */
4824 	enqueued  = cfs_rq->avg.util_est;
4825 	enqueued -= min_t(unsigned int, enqueued, _task_util_est(p));
4826 	WRITE_ONCE(cfs_rq->avg.util_est, enqueued);
4827 
4828 	trace_sched_util_est_cfs_tp(cfs_rq);
4829 }
4830 
4831 #define UTIL_EST_MARGIN (SCHED_CAPACITY_SCALE / 100)
4832 
4833 static inline void util_est_update(struct cfs_rq *cfs_rq,
4834 				   struct task_struct *p,
4835 				   bool task_sleep)
4836 {
4837 	unsigned int ewma, dequeued, last_ewma_diff;
4838 
4839 	if (!sched_feat(UTIL_EST))
4840 		return;
4841 
4842 	/*
4843 	 * Skip update of task's estimated utilization when the task has not
4844 	 * yet completed an activation, e.g. being migrated.
4845 	 */
4846 	if (!task_sleep)
4847 		return;
4848 
4849 	/* Get current estimate of utilization */
4850 	ewma = READ_ONCE(p->se.avg.util_est);
4851 
4852 	/*
4853 	 * If the PELT values haven't changed since enqueue time,
4854 	 * skip the util_est update.
4855 	 */
4856 	if (ewma & UTIL_AVG_UNCHANGED)
4857 		return;
4858 
4859 	/* Get utilization at dequeue */
4860 	dequeued = task_util(p);
4861 
4862 	/*
4863 	 * Reset EWMA on utilization increases, the moving average is used only
4864 	 * to smooth utilization decreases.
4865 	 */
4866 	if (ewma <= dequeued) {
4867 		ewma = dequeued;
4868 		goto done;
4869 	}
4870 
4871 	/*
4872 	 * Skip update of task's estimated utilization when its members are
4873 	 * already ~1% close to its last activation value.
4874 	 */
4875 	last_ewma_diff = ewma - dequeued;
4876 	if (last_ewma_diff < UTIL_EST_MARGIN)
4877 		goto done;
4878 
4879 	/*
4880 	 * To avoid underestimate of task utilization, skip updates of EWMA if
4881 	 * we cannot grant that thread got all CPU time it wanted.
4882 	 */
4883 	if ((dequeued + UTIL_EST_MARGIN) < task_runnable(p))
4884 		goto done;
4885 
4886 
4887 	/*
4888 	 * Update Task's estimated utilization
4889 	 *
4890 	 * When *p completes an activation we can consolidate another sample
4891 	 * of the task size. This is done by using this value to update the
4892 	 * Exponential Weighted Moving Average (EWMA):
4893 	 *
4894 	 *  ewma(t) = w *  task_util(p) + (1-w) * ewma(t-1)
4895 	 *          = w *  task_util(p) +         ewma(t-1)  - w * ewma(t-1)
4896 	 *          = w * (task_util(p) -         ewma(t-1)) +     ewma(t-1)
4897 	 *          = w * (      -last_ewma_diff           ) +     ewma(t-1)
4898 	 *          = w * (-last_ewma_diff +  ewma(t-1) / w)
4899 	 *
4900 	 * Where 'w' is the weight of new samples, which is configured to be
4901 	 * 0.25, thus making w=1/4 ( >>= UTIL_EST_WEIGHT_SHIFT)
4902 	 */
4903 	ewma <<= UTIL_EST_WEIGHT_SHIFT;
4904 	ewma  -= last_ewma_diff;
4905 	ewma >>= UTIL_EST_WEIGHT_SHIFT;
4906 done:
4907 	ewma |= UTIL_AVG_UNCHANGED;
4908 	WRITE_ONCE(p->se.avg.util_est, ewma);
4909 
4910 	trace_sched_util_est_se_tp(&p->se);
4911 }
4912 
4913 static inline unsigned long get_actual_cpu_capacity(int cpu)
4914 {
4915 	unsigned long capacity = arch_scale_cpu_capacity(cpu);
4916 
4917 	capacity -= max(hw_load_avg(cpu_rq(cpu)), cpufreq_get_pressure(cpu));
4918 
4919 	return capacity;
4920 }
4921 
4922 static inline int util_fits_cpu(unsigned long util,
4923 				unsigned long uclamp_min,
4924 				unsigned long uclamp_max,
4925 				int cpu)
4926 {
4927 	unsigned long capacity = capacity_of(cpu);
4928 	unsigned long capacity_orig;
4929 	bool fits, uclamp_max_fits;
4930 
4931 	/*
4932 	 * Check if the real util fits without any uclamp boost/cap applied.
4933 	 */
4934 	fits = fits_capacity(util, capacity);
4935 
4936 	if (!uclamp_is_used())
4937 		return fits;
4938 
4939 	/*
4940 	 * We must use arch_scale_cpu_capacity() for comparing against uclamp_min and
4941 	 * uclamp_max. We only care about capacity pressure (by using
4942 	 * capacity_of()) for comparing against the real util.
4943 	 *
4944 	 * If a task is boosted to 1024 for example, we don't want a tiny
4945 	 * pressure to skew the check whether it fits a CPU or not.
4946 	 *
4947 	 * Similarly if a task is capped to arch_scale_cpu_capacity(little_cpu), it
4948 	 * should fit a little cpu even if there's some pressure.
4949 	 *
4950 	 * Only exception is for HW or cpufreq pressure since it has a direct impact
4951 	 * on available OPP of the system.
4952 	 *
4953 	 * We honour it for uclamp_min only as a drop in performance level
4954 	 * could result in not getting the requested minimum performance level.
4955 	 *
4956 	 * For uclamp_max, we can tolerate a drop in performance level as the
4957 	 * goal is to cap the task. So it's okay if it's getting less.
4958 	 */
4959 	capacity_orig = arch_scale_cpu_capacity(cpu);
4960 
4961 	/*
4962 	 * We want to force a task to fit a cpu as implied by uclamp_max.
4963 	 * But we do have some corner cases to cater for..
4964 	 *
4965 	 *
4966 	 *                                 C=z
4967 	 *   |                             ___
4968 	 *   |                  C=y       |   |
4969 	 *   |_ _ _ _ _ _ _ _ _ ___ _ _ _ | _ | _ _ _ _ _  uclamp_max
4970 	 *   |      C=x        |   |      |   |
4971 	 *   |      ___        |   |      |   |
4972 	 *   |     |   |       |   |      |   |    (util somewhere in this region)
4973 	 *   |     |   |       |   |      |   |
4974 	 *   |     |   |       |   |      |   |
4975 	 *   +----------------------------------------
4976 	 *         CPU0        CPU1       CPU2
4977 	 *
4978 	 *   In the above example if a task is capped to a specific performance
4979 	 *   point, y, then when:
4980 	 *
4981 	 *   * util = 80% of x then it does not fit on CPU0 and should migrate
4982 	 *     to CPU1
4983 	 *   * util = 80% of y then it is forced to fit on CPU1 to honour
4984 	 *     uclamp_max request.
4985 	 *
4986 	 *   which is what we're enforcing here. A task always fits if
4987 	 *   uclamp_max <= capacity_orig. But when uclamp_max > capacity_orig,
4988 	 *   the normal upmigration rules should withhold still.
4989 	 *
4990 	 *   Only exception is when we are on max capacity, then we need to be
4991 	 *   careful not to block overutilized state. This is so because:
4992 	 *
4993 	 *     1. There's no concept of capping at max_capacity! We can't go
4994 	 *        beyond this performance level anyway.
4995 	 *     2. The system is being saturated when we're operating near
4996 	 *        max capacity, it doesn't make sense to block overutilized.
4997 	 */
4998 	uclamp_max_fits = (capacity_orig == SCHED_CAPACITY_SCALE) && (uclamp_max == SCHED_CAPACITY_SCALE);
4999 	uclamp_max_fits = !uclamp_max_fits && (uclamp_max <= capacity_orig);
5000 	fits = fits || uclamp_max_fits;
5001 
5002 	/*
5003 	 *
5004 	 *                                 C=z
5005 	 *   |                             ___       (region a, capped, util >= uclamp_max)
5006 	 *   |                  C=y       |   |
5007 	 *   |_ _ _ _ _ _ _ _ _ ___ _ _ _ | _ | _ _ _ _ _ uclamp_max
5008 	 *   |      C=x        |   |      |   |
5009 	 *   |      ___        |   |      |   |      (region b, uclamp_min <= util <= uclamp_max)
5010 	 *   |_ _ _|_ _|_ _ _ _| _ | _ _ _| _ | _ _ _ _ _ uclamp_min
5011 	 *   |     |   |       |   |      |   |
5012 	 *   |     |   |       |   |      |   |      (region c, boosted, util < uclamp_min)
5013 	 *   +----------------------------------------
5014 	 *         CPU0        CPU1       CPU2
5015 	 *
5016 	 * a) If util > uclamp_max, then we're capped, we don't care about
5017 	 *    actual fitness value here. We only care if uclamp_max fits
5018 	 *    capacity without taking margin/pressure into account.
5019 	 *    See comment above.
5020 	 *
5021 	 * b) If uclamp_min <= util <= uclamp_max, then the normal
5022 	 *    fits_capacity() rules apply. Except we need to ensure that we
5023 	 *    enforce we remain within uclamp_max, see comment above.
5024 	 *
5025 	 * c) If util < uclamp_min, then we are boosted. Same as (b) but we
5026 	 *    need to take into account the boosted value fits the CPU without
5027 	 *    taking margin/pressure into account.
5028 	 *
5029 	 * Cases (a) and (b) are handled in the 'fits' variable already. We
5030 	 * just need to consider an extra check for case (c) after ensuring we
5031 	 * handle the case uclamp_min > uclamp_max.
5032 	 */
5033 	uclamp_min = min(uclamp_min, uclamp_max);
5034 	if (fits && (util < uclamp_min) &&
5035 	    (uclamp_min > get_actual_cpu_capacity(cpu)))
5036 		return -1;
5037 
5038 	return fits;
5039 }
5040 
5041 static inline int task_fits_cpu(struct task_struct *p, int cpu)
5042 {
5043 	unsigned long uclamp_min = uclamp_eff_value(p, UCLAMP_MIN);
5044 	unsigned long uclamp_max = uclamp_eff_value(p, UCLAMP_MAX);
5045 	unsigned long util = task_util_est(p);
5046 	/*
5047 	 * Return true only if the cpu fully fits the task requirements, which
5048 	 * include the utilization but also the performance hints.
5049 	 */
5050 	return (util_fits_cpu(util, uclamp_min, uclamp_max, cpu) > 0);
5051 }
5052 
5053 static inline void update_misfit_status(struct task_struct *p, struct rq *rq)
5054 {
5055 	int cpu = cpu_of(rq);
5056 
5057 	if (!sched_asym_cpucap_active())
5058 		return;
5059 
5060 	/*
5061 	 * Affinity allows us to go somewhere higher?  Or are we on biggest
5062 	 * available CPU already? Or do we fit into this CPU ?
5063 	 */
5064 	if (!p || (p->nr_cpus_allowed == 1) ||
5065 	    (arch_scale_cpu_capacity(cpu) == p->max_allowed_capacity) ||
5066 	    task_fits_cpu(p, cpu)) {
5067 
5068 		rq->misfit_task_load = 0;
5069 		return;
5070 	}
5071 
5072 	/*
5073 	 * Make sure that misfit_task_load will not be null even if
5074 	 * task_h_load() returns 0.
5075 	 */
5076 	rq->misfit_task_load = max_t(unsigned long, task_h_load(p), 1);
5077 }
5078 
5079 void __setparam_fair(struct task_struct *p, const struct sched_attr *attr)
5080 {
5081 	struct sched_entity *se = &p->se;
5082 
5083 	p->static_prio = NICE_TO_PRIO(attr->sched_nice);
5084 	if (attr->sched_runtime) {
5085 		se->custom_slice = 1;
5086 		se->slice = clamp_t(u64, attr->sched_runtime,
5087 				      NSEC_PER_MSEC/10,   /* HZ=1000 * 10 */
5088 				      NSEC_PER_MSEC*100); /* HZ=100  / 10 */
5089 	} else {
5090 		se->custom_slice = 0;
5091 		se->slice = sysctl_sched_base_slice;
5092 	}
5093 }
5094 
5095 static void
5096 place_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags)
5097 {
5098 	u64 vslice, vruntime = avg_vruntime(cfs_rq);
5099 	s64 lag = 0;
5100 
5101 	if (!se->custom_slice)
5102 		se->slice = sysctl_sched_base_slice;
5103 	vslice = calc_delta_fair(se->slice, se);
5104 
5105 	/*
5106 	 * Due to how V is constructed as the weighted average of entities,
5107 	 * adding tasks with positive lag, or removing tasks with negative lag
5108 	 * will move 'time' backwards, this can screw around with the lag of
5109 	 * other tasks.
5110 	 *
5111 	 * EEVDF: placement strategy #1 / #2
5112 	 */
5113 	if (sched_feat(PLACE_LAG) && cfs_rq->nr_queued && se->vlag) {
5114 		struct sched_entity *curr = cfs_rq->curr;
5115 		unsigned long load;
5116 
5117 		lag = se->vlag;
5118 
5119 		/*
5120 		 * If we want to place a task and preserve lag, we have to
5121 		 * consider the effect of the new entity on the weighted
5122 		 * average and compensate for this, otherwise lag can quickly
5123 		 * evaporate.
5124 		 *
5125 		 * Lag is defined as:
5126 		 *
5127 		 *   lag_i = S - s_i = w_i * (V - v_i)
5128 		 *
5129 		 * To avoid the 'w_i' term all over the place, we only track
5130 		 * the virtual lag:
5131 		 *
5132 		 *   vl_i = V - v_i <=> v_i = V - vl_i
5133 		 *
5134 		 * And we take V to be the weighted average of all v:
5135 		 *
5136 		 *   V = (\Sum w_j*v_j) / W
5137 		 *
5138 		 * Where W is: \Sum w_j
5139 		 *
5140 		 * Then, the weighted average after adding an entity with lag
5141 		 * vl_i is given by:
5142 		 *
5143 		 *   V' = (\Sum w_j*v_j + w_i*v_i) / (W + w_i)
5144 		 *      = (W*V + w_i*(V - vl_i)) / (W + w_i)
5145 		 *      = (W*V + w_i*V - w_i*vl_i) / (W + w_i)
5146 		 *      = (V*(W + w_i) - w_i*vl_i) / (W + w_i)
5147 		 *      = V - w_i*vl_i / (W + w_i)
5148 		 *
5149 		 * And the actual lag after adding an entity with vl_i is:
5150 		 *
5151 		 *   vl'_i = V' - v_i
5152 		 *         = V - w_i*vl_i / (W + w_i) - (V - vl_i)
5153 		 *         = vl_i - w_i*vl_i / (W + w_i)
5154 		 *
5155 		 * Which is strictly less than vl_i. So in order to preserve lag
5156 		 * we should inflate the lag before placement such that the
5157 		 * effective lag after placement comes out right.
5158 		 *
5159 		 * As such, invert the above relation for vl'_i to get the vl_i
5160 		 * we need to use such that the lag after placement is the lag
5161 		 * we computed before dequeue.
5162 		 *
5163 		 *   vl'_i = vl_i - w_i*vl_i / (W + w_i)
5164 		 *         = ((W + w_i)*vl_i - w_i*vl_i) / (W + w_i)
5165 		 *
5166 		 *   (W + w_i)*vl'_i = (W + w_i)*vl_i - w_i*vl_i
5167 		 *                   = W*vl_i
5168 		 *
5169 		 *   vl_i = (W + w_i)*vl'_i / W
5170 		 */
5171 		load = cfs_rq->sum_weight;
5172 		if (curr && curr->on_rq)
5173 			load += scale_load_down(curr->load.weight);
5174 
5175 		lag *= load + scale_load_down(se->load.weight);
5176 		if (WARN_ON_ONCE(!load))
5177 			load = 1;
5178 		lag = div_s64(lag, load);
5179 	}
5180 
5181 	se->vruntime = vruntime - lag;
5182 
5183 	if (se->rel_deadline) {
5184 		se->deadline += se->vruntime;
5185 		se->rel_deadline = 0;
5186 		return;
5187 	}
5188 
5189 	/*
5190 	 * When joining the competition; the existing tasks will be,
5191 	 * on average, halfway through their slice, as such start tasks
5192 	 * off with half a slice to ease into the competition.
5193 	 */
5194 	if (sched_feat(PLACE_DEADLINE_INITIAL) && (flags & ENQUEUE_INITIAL))
5195 		vslice /= 2;
5196 
5197 	/*
5198 	 * EEVDF: vd_i = ve_i + r_i/w_i
5199 	 */
5200 	se->deadline = se->vruntime + vslice;
5201 }
5202 
5203 static void check_enqueue_throttle(struct cfs_rq *cfs_rq);
5204 static inline int cfs_rq_throttled(struct cfs_rq *cfs_rq);
5205 
5206 static void
5207 requeue_delayed_entity(struct sched_entity *se);
5208 
5209 static void
5210 enqueue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags)
5211 {
5212 	bool curr = cfs_rq->curr == se;
5213 
5214 	/*
5215 	 * If we're the current task, we must renormalise before calling
5216 	 * update_curr().
5217 	 */
5218 	if (curr)
5219 		place_entity(cfs_rq, se, flags);
5220 
5221 	update_curr(cfs_rq);
5222 
5223 	/*
5224 	 * When enqueuing a sched_entity, we must:
5225 	 *   - Update loads to have both entity and cfs_rq synced with now.
5226 	 *   - For group_entity, update its runnable_weight to reflect the new
5227 	 *     h_nr_runnable of its group cfs_rq.
5228 	 *   - For group_entity, update its weight to reflect the new share of
5229 	 *     its group cfs_rq
5230 	 *   - Add its new weight to cfs_rq->load.weight
5231 	 */
5232 	update_load_avg(cfs_rq, se, UPDATE_TG | DO_ATTACH);
5233 	se_update_runnable(se);
5234 	/*
5235 	 * XXX update_load_avg() above will have attached us to the pelt sum;
5236 	 * but update_cfs_group() here will re-adjust the weight and have to
5237 	 * undo/redo all that. Seems wasteful.
5238 	 */
5239 	update_cfs_group(se);
5240 
5241 	/*
5242 	 * XXX now that the entity has been re-weighted, and it's lag adjusted,
5243 	 * we can place the entity.
5244 	 */
5245 	if (!curr)
5246 		place_entity(cfs_rq, se, flags);
5247 
5248 	account_entity_enqueue(cfs_rq, se);
5249 
5250 	/* Entity has migrated, no longer consider this task hot */
5251 	if (flags & ENQUEUE_MIGRATED)
5252 		se->exec_start = 0;
5253 
5254 	check_schedstat_required();
5255 	update_stats_enqueue_fair(cfs_rq, se, flags);
5256 	if (!curr)
5257 		__enqueue_entity(cfs_rq, se);
5258 	se->on_rq = 1;
5259 
5260 	if (cfs_rq->nr_queued == 1) {
5261 		check_enqueue_throttle(cfs_rq);
5262 		list_add_leaf_cfs_rq(cfs_rq);
5263 #ifdef CONFIG_CFS_BANDWIDTH
5264 		if (cfs_rq->pelt_clock_throttled) {
5265 			struct rq *rq = rq_of(cfs_rq);
5266 
5267 			cfs_rq->throttled_clock_pelt_time += rq_clock_pelt(rq) -
5268 				cfs_rq->throttled_clock_pelt;
5269 			cfs_rq->pelt_clock_throttled = 0;
5270 		}
5271 #endif
5272 	}
5273 }
5274 
5275 static void __clear_buddies_next(struct sched_entity *se)
5276 {
5277 	for_each_sched_entity(se) {
5278 		struct cfs_rq *cfs_rq = cfs_rq_of(se);
5279 		if (cfs_rq->next != se)
5280 			break;
5281 
5282 		cfs_rq->next = NULL;
5283 	}
5284 }
5285 
5286 static void clear_buddies(struct cfs_rq *cfs_rq, struct sched_entity *se)
5287 {
5288 	if (cfs_rq->next == se)
5289 		__clear_buddies_next(se);
5290 }
5291 
5292 static __always_inline void return_cfs_rq_runtime(struct cfs_rq *cfs_rq);
5293 
5294 static void set_delayed(struct sched_entity *se)
5295 {
5296 	se->sched_delayed = 1;
5297 
5298 	/*
5299 	 * Delayed se of cfs_rq have no tasks queued on them.
5300 	 * Do not adjust h_nr_runnable since dequeue_entities()
5301 	 * will account it for blocked tasks.
5302 	 */
5303 	if (!entity_is_task(se))
5304 		return;
5305 
5306 	for_each_sched_entity(se) {
5307 		struct cfs_rq *cfs_rq = cfs_rq_of(se);
5308 
5309 		cfs_rq->h_nr_runnable--;
5310 	}
5311 }
5312 
5313 static void clear_delayed(struct sched_entity *se)
5314 {
5315 	se->sched_delayed = 0;
5316 
5317 	/*
5318 	 * Delayed se of cfs_rq have no tasks queued on them.
5319 	 * Do not adjust h_nr_runnable since a dequeue has
5320 	 * already accounted for it or an enqueue of a task
5321 	 * below it will account for it in enqueue_task_fair().
5322 	 */
5323 	if (!entity_is_task(se))
5324 		return;
5325 
5326 	for_each_sched_entity(se) {
5327 		struct cfs_rq *cfs_rq = cfs_rq_of(se);
5328 
5329 		cfs_rq->h_nr_runnable++;
5330 	}
5331 }
5332 
5333 static inline void finish_delayed_dequeue_entity(struct sched_entity *se)
5334 {
5335 	clear_delayed(se);
5336 	if (sched_feat(DELAY_ZERO) && se->vlag > 0)
5337 		se->vlag = 0;
5338 }
5339 
5340 static bool
5341 dequeue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags)
5342 {
5343 	bool sleep = flags & DEQUEUE_SLEEP;
5344 	int action = UPDATE_TG;
5345 
5346 	update_curr(cfs_rq);
5347 	clear_buddies(cfs_rq, se);
5348 
5349 	if (flags & DEQUEUE_DELAYED) {
5350 		WARN_ON_ONCE(!se->sched_delayed);
5351 	} else {
5352 		bool delay = sleep;
5353 		/*
5354 		 * DELAY_DEQUEUE relies on spurious wakeups, special task
5355 		 * states must not suffer spurious wakeups, excempt them.
5356 		 */
5357 		if (flags & (DEQUEUE_SPECIAL | DEQUEUE_THROTTLE))
5358 			delay = false;
5359 
5360 		WARN_ON_ONCE(delay && se->sched_delayed);
5361 
5362 		if (sched_feat(DELAY_DEQUEUE) && delay &&
5363 		    !entity_eligible(cfs_rq, se)) {
5364 			update_load_avg(cfs_rq, se, 0);
5365 			set_delayed(se);
5366 			return false;
5367 		}
5368 	}
5369 
5370 	if (entity_is_task(se) && task_on_rq_migrating(task_of(se)))
5371 		action |= DO_DETACH;
5372 
5373 	/*
5374 	 * When dequeuing a sched_entity, we must:
5375 	 *   - Update loads to have both entity and cfs_rq synced with now.
5376 	 *   - For group_entity, update its runnable_weight to reflect the new
5377 	 *     h_nr_runnable of its group cfs_rq.
5378 	 *   - Subtract its previous weight from cfs_rq->load.weight.
5379 	 *   - For group entity, update its weight to reflect the new share
5380 	 *     of its group cfs_rq.
5381 	 */
5382 	update_load_avg(cfs_rq, se, action);
5383 	se_update_runnable(se);
5384 
5385 	update_stats_dequeue_fair(cfs_rq, se, flags);
5386 
5387 	update_entity_lag(cfs_rq, se);
5388 	if (sched_feat(PLACE_REL_DEADLINE) && !sleep) {
5389 		se->deadline -= se->vruntime;
5390 		se->rel_deadline = 1;
5391 	}
5392 
5393 	if (se != cfs_rq->curr)
5394 		__dequeue_entity(cfs_rq, se);
5395 	se->on_rq = 0;
5396 	account_entity_dequeue(cfs_rq, se);
5397 
5398 	/* return excess runtime on last dequeue */
5399 	return_cfs_rq_runtime(cfs_rq);
5400 
5401 	update_cfs_group(se);
5402 
5403 	if (flags & DEQUEUE_DELAYED)
5404 		finish_delayed_dequeue_entity(se);
5405 
5406 	if (cfs_rq->nr_queued == 0) {
5407 		update_idle_cfs_rq_clock_pelt(cfs_rq);
5408 #ifdef CONFIG_CFS_BANDWIDTH
5409 		if (throttled_hierarchy(cfs_rq)) {
5410 			struct rq *rq = rq_of(cfs_rq);
5411 
5412 			list_del_leaf_cfs_rq(cfs_rq);
5413 			cfs_rq->throttled_clock_pelt = rq_clock_pelt(rq);
5414 			cfs_rq->pelt_clock_throttled = 1;
5415 		}
5416 #endif
5417 	}
5418 
5419 	return true;
5420 }
5421 
5422 static void
5423 set_next_entity(struct cfs_rq *cfs_rq, struct sched_entity *se)
5424 {
5425 	clear_buddies(cfs_rq, se);
5426 
5427 	/* 'current' is not kept within the tree. */
5428 	if (se->on_rq) {
5429 		/*
5430 		 * Any task has to be enqueued before it get to execute on
5431 		 * a CPU. So account for the time it spent waiting on the
5432 		 * runqueue.
5433 		 */
5434 		update_stats_wait_end_fair(cfs_rq, se);
5435 		__dequeue_entity(cfs_rq, se);
5436 		update_load_avg(cfs_rq, se, UPDATE_TG);
5437 
5438 		set_protect_slice(cfs_rq, se);
5439 	}
5440 
5441 	update_stats_curr_start(cfs_rq, se);
5442 	WARN_ON_ONCE(cfs_rq->curr);
5443 	cfs_rq->curr = se;
5444 
5445 	/*
5446 	 * Track our maximum slice length, if the CPU's load is at
5447 	 * least twice that of our own weight (i.e. don't track it
5448 	 * when there are only lesser-weight tasks around):
5449 	 */
5450 	if (schedstat_enabled() &&
5451 	    rq_of(cfs_rq)->cfs.load.weight >= 2*se->load.weight) {
5452 		struct sched_statistics *stats;
5453 
5454 		stats = __schedstats_from_se(se);
5455 		__schedstat_set(stats->slice_max,
5456 				max((u64)stats->slice_max,
5457 				    se->sum_exec_runtime - se->prev_sum_exec_runtime));
5458 	}
5459 
5460 	se->prev_sum_exec_runtime = se->sum_exec_runtime;
5461 }
5462 
5463 static int dequeue_entities(struct rq *rq, struct sched_entity *se, int flags);
5464 
5465 /*
5466  * Pick the next process, keeping these things in mind, in this order:
5467  * 1) keep things fair between processes/task groups
5468  * 2) pick the "next" process, since someone really wants that to run
5469  * 3) pick the "last" process, for cache locality
5470  * 4) do not run the "skip" process, if something else is available
5471  */
5472 static struct sched_entity *
5473 pick_next_entity(struct rq *rq, struct cfs_rq *cfs_rq)
5474 {
5475 	struct sched_entity *se;
5476 
5477 	se = pick_eevdf(cfs_rq);
5478 	if (se->sched_delayed) {
5479 		dequeue_entities(rq, se, DEQUEUE_SLEEP | DEQUEUE_DELAYED);
5480 		/*
5481 		 * Must not reference @se again, see __block_task().
5482 		 */
5483 		return NULL;
5484 	}
5485 	return se;
5486 }
5487 
5488 static bool check_cfs_rq_runtime(struct cfs_rq *cfs_rq);
5489 
5490 static void put_prev_entity(struct cfs_rq *cfs_rq, struct sched_entity *prev)
5491 {
5492 	/*
5493 	 * If still on the runqueue then deactivate_task()
5494 	 * was not called and update_curr() has to be done:
5495 	 */
5496 	if (prev->on_rq)
5497 		update_curr(cfs_rq);
5498 
5499 	/* throttle cfs_rqs exceeding runtime */
5500 	check_cfs_rq_runtime(cfs_rq);
5501 
5502 	if (prev->on_rq) {
5503 		update_stats_wait_start_fair(cfs_rq, prev);
5504 		/* Put 'current' back into the tree. */
5505 		__enqueue_entity(cfs_rq, prev);
5506 		/* in !on_rq case, update occurred at dequeue */
5507 		update_load_avg(cfs_rq, prev, 0);
5508 	}
5509 	WARN_ON_ONCE(cfs_rq->curr != prev);
5510 	cfs_rq->curr = NULL;
5511 }
5512 
5513 static void
5514 entity_tick(struct cfs_rq *cfs_rq, struct sched_entity *curr, int queued)
5515 {
5516 	/*
5517 	 * Update run-time statistics of the 'current'.
5518 	 */
5519 	update_curr(cfs_rq);
5520 
5521 	/*
5522 	 * Ensure that runnable average is periodically updated.
5523 	 */
5524 	update_load_avg(cfs_rq, curr, UPDATE_TG);
5525 	update_cfs_group(curr);
5526 
5527 #ifdef CONFIG_SCHED_HRTICK
5528 	/*
5529 	 * queued ticks are scheduled to match the slice, so don't bother
5530 	 * validating it and just reschedule.
5531 	 */
5532 	if (queued) {
5533 		resched_curr_lazy(rq_of(cfs_rq));
5534 		return;
5535 	}
5536 #endif
5537 }
5538 
5539 
5540 /**************************************************
5541  * CFS bandwidth control machinery
5542  */
5543 
5544 #ifdef CONFIG_CFS_BANDWIDTH
5545 
5546 #ifdef CONFIG_JUMP_LABEL
5547 static struct static_key __cfs_bandwidth_used;
5548 
5549 static inline bool cfs_bandwidth_used(void)
5550 {
5551 	return static_key_false(&__cfs_bandwidth_used);
5552 }
5553 
5554 void cfs_bandwidth_usage_inc(void)
5555 {
5556 	static_key_slow_inc_cpuslocked(&__cfs_bandwidth_used);
5557 }
5558 
5559 void cfs_bandwidth_usage_dec(void)
5560 {
5561 	static_key_slow_dec_cpuslocked(&__cfs_bandwidth_used);
5562 }
5563 #else /* !CONFIG_JUMP_LABEL: */
5564 static bool cfs_bandwidth_used(void)
5565 {
5566 	return true;
5567 }
5568 
5569 void cfs_bandwidth_usage_inc(void) {}
5570 void cfs_bandwidth_usage_dec(void) {}
5571 #endif /* !CONFIG_JUMP_LABEL */
5572 
5573 static inline u64 sched_cfs_bandwidth_slice(void)
5574 {
5575 	return (u64)sysctl_sched_cfs_bandwidth_slice * NSEC_PER_USEC;
5576 }
5577 
5578 /*
5579  * Replenish runtime according to assigned quota. We use sched_clock_cpu
5580  * directly instead of rq->clock to avoid adding additional synchronization
5581  * around rq->lock.
5582  *
5583  * requires cfs_b->lock
5584  */
5585 void __refill_cfs_bandwidth_runtime(struct cfs_bandwidth *cfs_b)
5586 {
5587 	s64 runtime;
5588 
5589 	if (unlikely(cfs_b->quota == RUNTIME_INF))
5590 		return;
5591 
5592 	cfs_b->runtime += cfs_b->quota;
5593 	runtime = cfs_b->runtime_snap - cfs_b->runtime;
5594 	if (runtime > 0) {
5595 		cfs_b->burst_time += runtime;
5596 		cfs_b->nr_burst++;
5597 	}
5598 
5599 	cfs_b->runtime = min(cfs_b->runtime, cfs_b->quota + cfs_b->burst);
5600 	cfs_b->runtime_snap = cfs_b->runtime;
5601 }
5602 
5603 static inline struct cfs_bandwidth *tg_cfs_bandwidth(struct task_group *tg)
5604 {
5605 	return &tg->cfs_bandwidth;
5606 }
5607 
5608 /* returns 0 on failure to allocate runtime */
5609 static int __assign_cfs_rq_runtime(struct cfs_bandwidth *cfs_b,
5610 				   struct cfs_rq *cfs_rq, u64 target_runtime)
5611 {
5612 	u64 min_amount, amount = 0;
5613 
5614 	lockdep_assert_held(&cfs_b->lock);
5615 
5616 	/* note: this is a positive sum as runtime_remaining <= 0 */
5617 	min_amount = target_runtime - cfs_rq->runtime_remaining;
5618 
5619 	if (cfs_b->quota == RUNTIME_INF)
5620 		amount = min_amount;
5621 	else {
5622 		start_cfs_bandwidth(cfs_b);
5623 
5624 		if (cfs_b->runtime > 0) {
5625 			amount = min(cfs_b->runtime, min_amount);
5626 			cfs_b->runtime -= amount;
5627 			cfs_b->idle = 0;
5628 		}
5629 	}
5630 
5631 	cfs_rq->runtime_remaining += amount;
5632 
5633 	return cfs_rq->runtime_remaining > 0;
5634 }
5635 
5636 /* returns 0 on failure to allocate runtime */
5637 static int assign_cfs_rq_runtime(struct cfs_rq *cfs_rq)
5638 {
5639 	struct cfs_bandwidth *cfs_b = tg_cfs_bandwidth(cfs_rq->tg);
5640 	int ret;
5641 
5642 	raw_spin_lock(&cfs_b->lock);
5643 	ret = __assign_cfs_rq_runtime(cfs_b, cfs_rq, sched_cfs_bandwidth_slice());
5644 	raw_spin_unlock(&cfs_b->lock);
5645 
5646 	return ret;
5647 }
5648 
5649 static void __account_cfs_rq_runtime(struct cfs_rq *cfs_rq, u64 delta_exec)
5650 {
5651 	/* dock delta_exec before expiring quota (as it could span periods) */
5652 	cfs_rq->runtime_remaining -= delta_exec;
5653 
5654 	if (likely(cfs_rq->runtime_remaining > 0))
5655 		return;
5656 
5657 	if (cfs_rq->throttled)
5658 		return;
5659 	/*
5660 	 * if we're unable to extend our runtime we resched so that the active
5661 	 * hierarchy can be throttled
5662 	 */
5663 	if (!assign_cfs_rq_runtime(cfs_rq) && likely(cfs_rq->curr))
5664 		resched_curr(rq_of(cfs_rq));
5665 }
5666 
5667 static __always_inline
5668 void account_cfs_rq_runtime(struct cfs_rq *cfs_rq, u64 delta_exec)
5669 {
5670 	if (!cfs_bandwidth_used() || !cfs_rq->runtime_enabled)
5671 		return;
5672 
5673 	__account_cfs_rq_runtime(cfs_rq, delta_exec);
5674 }
5675 
5676 static inline int cfs_rq_throttled(struct cfs_rq *cfs_rq)
5677 {
5678 	return cfs_bandwidth_used() && cfs_rq->throttled;
5679 }
5680 
5681 static inline bool cfs_rq_pelt_clock_throttled(struct cfs_rq *cfs_rq)
5682 {
5683 	return cfs_bandwidth_used() && cfs_rq->pelt_clock_throttled;
5684 }
5685 
5686 /* check whether cfs_rq, or any parent, is throttled */
5687 static inline int throttled_hierarchy(struct cfs_rq *cfs_rq)
5688 {
5689 	return cfs_bandwidth_used() && cfs_rq->throttle_count;
5690 }
5691 
5692 static inline int lb_throttled_hierarchy(struct task_struct *p, int dst_cpu)
5693 {
5694 	return throttled_hierarchy(task_group(p)->cfs_rq[dst_cpu]);
5695 }
5696 
5697 static inline bool task_is_throttled(struct task_struct *p)
5698 {
5699 	return cfs_bandwidth_used() && p->throttled;
5700 }
5701 
5702 static bool dequeue_task_fair(struct rq *rq, struct task_struct *p, int flags);
5703 static void throttle_cfs_rq_work(struct callback_head *work)
5704 {
5705 	struct task_struct *p = container_of(work, struct task_struct, sched_throttle_work);
5706 	struct sched_entity *se;
5707 	struct cfs_rq *cfs_rq;
5708 	struct rq *rq;
5709 
5710 	WARN_ON_ONCE(p != current);
5711 	p->sched_throttle_work.next = &p->sched_throttle_work;
5712 
5713 	/*
5714 	 * If task is exiting, then there won't be a return to userspace, so we
5715 	 * don't have to bother with any of this.
5716 	 */
5717 	if ((p->flags & PF_EXITING))
5718 		return;
5719 
5720 	scoped_guard(task_rq_lock, p) {
5721 		se = &p->se;
5722 		cfs_rq = cfs_rq_of(se);
5723 
5724 		/* Raced, forget */
5725 		if (p->sched_class != &fair_sched_class)
5726 			return;
5727 
5728 		/*
5729 		 * If not in limbo, then either replenish has happened or this
5730 		 * task got migrated out of the throttled cfs_rq, move along.
5731 		 */
5732 		if (!cfs_rq->throttle_count)
5733 			return;
5734 		rq = scope.rq;
5735 		update_rq_clock(rq);
5736 		WARN_ON_ONCE(p->throttled || !list_empty(&p->throttle_node));
5737 		dequeue_task_fair(rq, p, DEQUEUE_SLEEP | DEQUEUE_THROTTLE);
5738 		list_add(&p->throttle_node, &cfs_rq->throttled_limbo_list);
5739 		/*
5740 		 * Must not set throttled before dequeue or dequeue will
5741 		 * mistakenly regard this task as an already throttled one.
5742 		 */
5743 		p->throttled = true;
5744 		resched_curr(rq);
5745 	}
5746 }
5747 
5748 void init_cfs_throttle_work(struct task_struct *p)
5749 {
5750 	init_task_work(&p->sched_throttle_work, throttle_cfs_rq_work);
5751 	/* Protect against double add, see throttle_cfs_rq() and throttle_cfs_rq_work() */
5752 	p->sched_throttle_work.next = &p->sched_throttle_work;
5753 	INIT_LIST_HEAD(&p->throttle_node);
5754 }
5755 
5756 /*
5757  * Task is throttled and someone wants to dequeue it again:
5758  * it could be sched/core when core needs to do things like
5759  * task affinity change, task group change, task sched class
5760  * change etc. and in these cases, DEQUEUE_SLEEP is not set;
5761  * or the task is blocked after throttled due to freezer etc.
5762  * and in these cases, DEQUEUE_SLEEP is set.
5763  */
5764 static void detach_task_cfs_rq(struct task_struct *p);
5765 static void dequeue_throttled_task(struct task_struct *p, int flags)
5766 {
5767 	WARN_ON_ONCE(p->se.on_rq);
5768 	list_del_init(&p->throttle_node);
5769 
5770 	/* task blocked after throttled */
5771 	if (flags & DEQUEUE_SLEEP) {
5772 		p->throttled = false;
5773 		return;
5774 	}
5775 
5776 	/*
5777 	 * task is migrating off its old cfs_rq, detach
5778 	 * the task's load from its old cfs_rq.
5779 	 */
5780 	if (task_on_rq_migrating(p))
5781 		detach_task_cfs_rq(p);
5782 }
5783 
5784 static bool enqueue_throttled_task(struct task_struct *p)
5785 {
5786 	struct cfs_rq *cfs_rq = cfs_rq_of(&p->se);
5787 
5788 	/* @p should have gone through dequeue_throttled_task() first */
5789 	WARN_ON_ONCE(!list_empty(&p->throttle_node));
5790 
5791 	/*
5792 	 * If the throttled task @p is enqueued to a throttled cfs_rq,
5793 	 * take the fast path by directly putting the task on the
5794 	 * target cfs_rq's limbo list.
5795 	 *
5796 	 * Do not do that when @p is current because the following race can
5797 	 * cause @p's group_node to be incorectly re-insterted in its rq's
5798 	 * cfs_tasks list, despite being throttled:
5799 	 *
5800 	 *     cpuX                       cpuY
5801 	 *   p ret2user
5802 	 *  throttle_cfs_rq_work()  sched_move_task(p)
5803 	 *  LOCK task_rq_lock
5804 	 *  dequeue_task_fair(p)
5805 	 *  UNLOCK task_rq_lock
5806 	 *                          LOCK task_rq_lock
5807 	 *                          task_current_donor(p) == true
5808 	 *                          task_on_rq_queued(p) == true
5809 	 *                          dequeue_task(p)
5810 	 *                          put_prev_task(p)
5811 	 *                          sched_change_group()
5812 	 *                          enqueue_task(p) -> p's new cfs_rq
5813 	 *                                             is throttled, go
5814 	 *                                             fast path and skip
5815 	 *                                             actual enqueue
5816 	 *                          set_next_task(p)
5817 	 *                    list_move(&se->group_node, &rq->cfs_tasks); // bug
5818 	 *  schedule()
5819 	 *
5820 	 * In the above race case, @p current cfs_rq is in the same rq as
5821 	 * its previous cfs_rq because sched_move_task() only moves a task
5822 	 * to a different group from the same rq, so we can use its current
5823 	 * cfs_rq to derive rq and test if the task is current.
5824 	 */
5825 	if (throttled_hierarchy(cfs_rq) &&
5826 	    !task_current_donor(rq_of(cfs_rq), p)) {
5827 		list_add(&p->throttle_node, &cfs_rq->throttled_limbo_list);
5828 		return true;
5829 	}
5830 
5831 	/* we can't take the fast path, do an actual enqueue*/
5832 	p->throttled = false;
5833 	return false;
5834 }
5835 
5836 static void enqueue_task_fair(struct rq *rq, struct task_struct *p, int flags);
5837 static int tg_unthrottle_up(struct task_group *tg, void *data)
5838 {
5839 	struct rq *rq = data;
5840 	struct cfs_rq *cfs_rq = tg->cfs_rq[cpu_of(rq)];
5841 	struct task_struct *p, *tmp;
5842 
5843 	if (--cfs_rq->throttle_count)
5844 		return 0;
5845 
5846 	if (cfs_rq->pelt_clock_throttled) {
5847 		cfs_rq->throttled_clock_pelt_time += rq_clock_pelt(rq) -
5848 					     cfs_rq->throttled_clock_pelt;
5849 		cfs_rq->pelt_clock_throttled = 0;
5850 	}
5851 
5852 	if (cfs_rq->throttled_clock_self) {
5853 		u64 delta = rq_clock(rq) - cfs_rq->throttled_clock_self;
5854 
5855 		cfs_rq->throttled_clock_self = 0;
5856 
5857 		if (WARN_ON_ONCE((s64)delta < 0))
5858 			delta = 0;
5859 
5860 		cfs_rq->throttled_clock_self_time += delta;
5861 	}
5862 
5863 	/* Re-enqueue the tasks that have been throttled at this level. */
5864 	list_for_each_entry_safe(p, tmp, &cfs_rq->throttled_limbo_list, throttle_node) {
5865 		list_del_init(&p->throttle_node);
5866 		p->throttled = false;
5867 		enqueue_task_fair(rq_of(cfs_rq), p, ENQUEUE_WAKEUP);
5868 	}
5869 
5870 	/* Add cfs_rq with load or one or more already running entities to the list */
5871 	if (!cfs_rq_is_decayed(cfs_rq))
5872 		list_add_leaf_cfs_rq(cfs_rq);
5873 
5874 	return 0;
5875 }
5876 
5877 static inline bool task_has_throttle_work(struct task_struct *p)
5878 {
5879 	return p->sched_throttle_work.next != &p->sched_throttle_work;
5880 }
5881 
5882 static inline void task_throttle_setup_work(struct task_struct *p)
5883 {
5884 	if (task_has_throttle_work(p))
5885 		return;
5886 
5887 	/*
5888 	 * Kthreads and exiting tasks don't return to userspace, so adding the
5889 	 * work is pointless
5890 	 */
5891 	if ((p->flags & (PF_EXITING | PF_KTHREAD)))
5892 		return;
5893 
5894 	task_work_add(p, &p->sched_throttle_work, TWA_RESUME);
5895 }
5896 
5897 static void record_throttle_clock(struct cfs_rq *cfs_rq)
5898 {
5899 	struct rq *rq = rq_of(cfs_rq);
5900 
5901 	if (cfs_rq_throttled(cfs_rq) && !cfs_rq->throttled_clock)
5902 		cfs_rq->throttled_clock = rq_clock(rq);
5903 
5904 	if (!cfs_rq->throttled_clock_self)
5905 		cfs_rq->throttled_clock_self = rq_clock(rq);
5906 }
5907 
5908 static int tg_throttle_down(struct task_group *tg, void *data)
5909 {
5910 	struct rq *rq = data;
5911 	struct cfs_rq *cfs_rq = tg->cfs_rq[cpu_of(rq)];
5912 
5913 	if (cfs_rq->throttle_count++)
5914 		return 0;
5915 
5916 	/*
5917 	 * For cfs_rqs that still have entities enqueued, PELT clock
5918 	 * stop happens at dequeue time when all entities are dequeued.
5919 	 */
5920 	if (!cfs_rq->nr_queued) {
5921 		list_del_leaf_cfs_rq(cfs_rq);
5922 		cfs_rq->throttled_clock_pelt = rq_clock_pelt(rq);
5923 		cfs_rq->pelt_clock_throttled = 1;
5924 	}
5925 
5926 	WARN_ON_ONCE(cfs_rq->throttled_clock_self);
5927 	WARN_ON_ONCE(!list_empty(&cfs_rq->throttled_limbo_list));
5928 	return 0;
5929 }
5930 
5931 static bool throttle_cfs_rq(struct cfs_rq *cfs_rq)
5932 {
5933 	struct rq *rq = rq_of(cfs_rq);
5934 	struct cfs_bandwidth *cfs_b = tg_cfs_bandwidth(cfs_rq->tg);
5935 	int dequeue = 1;
5936 
5937 	raw_spin_lock(&cfs_b->lock);
5938 	/* This will start the period timer if necessary */
5939 	if (__assign_cfs_rq_runtime(cfs_b, cfs_rq, 1)) {
5940 		/*
5941 		 * We have raced with bandwidth becoming available, and if we
5942 		 * actually throttled the timer might not unthrottle us for an
5943 		 * entire period. We additionally needed to make sure that any
5944 		 * subsequent check_cfs_rq_runtime calls agree not to throttle
5945 		 * us, as we may commit to do cfs put_prev+pick_next, so we ask
5946 		 * for 1ns of runtime rather than just check cfs_b.
5947 		 */
5948 		dequeue = 0;
5949 	} else {
5950 		list_add_tail_rcu(&cfs_rq->throttled_list,
5951 				  &cfs_b->throttled_cfs_rq);
5952 	}
5953 	raw_spin_unlock(&cfs_b->lock);
5954 
5955 	if (!dequeue)
5956 		return false;  /* Throttle no longer required. */
5957 
5958 	/* freeze hierarchy runnable averages while throttled */
5959 	rcu_read_lock();
5960 	walk_tg_tree_from(cfs_rq->tg, tg_throttle_down, tg_nop, (void *)rq);
5961 	rcu_read_unlock();
5962 
5963 	/*
5964 	 * Note: distribution will already see us throttled via the
5965 	 * throttled-list.  rq->lock protects completion.
5966 	 */
5967 	cfs_rq->throttled = 1;
5968 	WARN_ON_ONCE(cfs_rq->throttled_clock);
5969 	return true;
5970 }
5971 
5972 void unthrottle_cfs_rq(struct cfs_rq *cfs_rq)
5973 {
5974 	struct rq *rq = rq_of(cfs_rq);
5975 	struct cfs_bandwidth *cfs_b = tg_cfs_bandwidth(cfs_rq->tg);
5976 	struct sched_entity *se = cfs_rq->tg->se[cpu_of(rq)];
5977 
5978 	/*
5979 	 * It's possible we are called with runtime_remaining < 0 due to things
5980 	 * like async unthrottled us with a positive runtime_remaining but other
5981 	 * still running entities consumed those runtime before we reached here.
5982 	 *
5983 	 * We can't unthrottle this cfs_rq without any runtime remaining because
5984 	 * any enqueue in tg_unthrottle_up() will immediately trigger a throttle,
5985 	 * which is not supposed to happen on unthrottle path.
5986 	 */
5987 	if (cfs_rq->runtime_enabled && cfs_rq->runtime_remaining <= 0)
5988 		return;
5989 
5990 	cfs_rq->throttled = 0;
5991 
5992 	update_rq_clock(rq);
5993 
5994 	raw_spin_lock(&cfs_b->lock);
5995 	if (cfs_rq->throttled_clock) {
5996 		cfs_b->throttled_time += rq_clock(rq) - cfs_rq->throttled_clock;
5997 		cfs_rq->throttled_clock = 0;
5998 	}
5999 	list_del_rcu(&cfs_rq->throttled_list);
6000 	raw_spin_unlock(&cfs_b->lock);
6001 
6002 	/* update hierarchical throttle state */
6003 	walk_tg_tree_from(cfs_rq->tg, tg_nop, tg_unthrottle_up, (void *)rq);
6004 
6005 	if (!cfs_rq->load.weight) {
6006 		if (!cfs_rq->on_list)
6007 			return;
6008 		/*
6009 		 * Nothing to run but something to decay (on_list)?
6010 		 * Complete the branch.
6011 		 */
6012 		for_each_sched_entity(se) {
6013 			if (list_add_leaf_cfs_rq(cfs_rq_of(se)))
6014 				break;
6015 		}
6016 	}
6017 
6018 	assert_list_leaf_cfs_rq(rq);
6019 
6020 	/* Determine whether we need to wake up potentially idle CPU: */
6021 	if (rq->curr == rq->idle && rq->cfs.nr_queued)
6022 		resched_curr(rq);
6023 }
6024 
6025 static void __cfsb_csd_unthrottle(void *arg)
6026 {
6027 	struct cfs_rq *cursor, *tmp;
6028 	struct rq *rq = arg;
6029 	struct rq_flags rf;
6030 
6031 	rq_lock(rq, &rf);
6032 
6033 	/*
6034 	 * Iterating over the list can trigger several call to
6035 	 * update_rq_clock() in unthrottle_cfs_rq().
6036 	 * Do it once and skip the potential next ones.
6037 	 */
6038 	update_rq_clock(rq);
6039 	rq_clock_start_loop_update(rq);
6040 
6041 	/*
6042 	 * Since we hold rq lock we're safe from concurrent manipulation of
6043 	 * the CSD list. However, this RCU critical section annotates the
6044 	 * fact that we pair with sched_free_group_rcu(), so that we cannot
6045 	 * race with group being freed in the window between removing it
6046 	 * from the list and advancing to the next entry in the list.
6047 	 */
6048 	rcu_read_lock();
6049 
6050 	list_for_each_entry_safe(cursor, tmp, &rq->cfsb_csd_list,
6051 				 throttled_csd_list) {
6052 		list_del_init(&cursor->throttled_csd_list);
6053 
6054 		if (cfs_rq_throttled(cursor))
6055 			unthrottle_cfs_rq(cursor);
6056 	}
6057 
6058 	rcu_read_unlock();
6059 
6060 	rq_clock_stop_loop_update(rq);
6061 	rq_unlock(rq, &rf);
6062 }
6063 
6064 static inline void __unthrottle_cfs_rq_async(struct cfs_rq *cfs_rq)
6065 {
6066 	struct rq *rq = rq_of(cfs_rq);
6067 	bool first;
6068 
6069 	if (rq == this_rq()) {
6070 		unthrottle_cfs_rq(cfs_rq);
6071 		return;
6072 	}
6073 
6074 	/* Already enqueued */
6075 	if (WARN_ON_ONCE(!list_empty(&cfs_rq->throttled_csd_list)))
6076 		return;
6077 
6078 	first = list_empty(&rq->cfsb_csd_list);
6079 	list_add_tail(&cfs_rq->throttled_csd_list, &rq->cfsb_csd_list);
6080 	if (first)
6081 		smp_call_function_single_async(cpu_of(rq), &rq->cfsb_csd);
6082 }
6083 
6084 static void unthrottle_cfs_rq_async(struct cfs_rq *cfs_rq)
6085 {
6086 	lockdep_assert_rq_held(rq_of(cfs_rq));
6087 
6088 	if (WARN_ON_ONCE(!cfs_rq_throttled(cfs_rq) ||
6089 	    cfs_rq->runtime_remaining <= 0))
6090 		return;
6091 
6092 	__unthrottle_cfs_rq_async(cfs_rq);
6093 }
6094 
6095 static bool distribute_cfs_runtime(struct cfs_bandwidth *cfs_b)
6096 {
6097 	int this_cpu = smp_processor_id();
6098 	u64 runtime, remaining = 1;
6099 	bool throttled = false;
6100 	struct cfs_rq *cfs_rq, *tmp;
6101 	struct rq_flags rf;
6102 	struct rq *rq;
6103 	LIST_HEAD(local_unthrottle);
6104 
6105 	rcu_read_lock();
6106 	list_for_each_entry_rcu(cfs_rq, &cfs_b->throttled_cfs_rq,
6107 				throttled_list) {
6108 		rq = rq_of(cfs_rq);
6109 
6110 		if (!remaining) {
6111 			throttled = true;
6112 			break;
6113 		}
6114 
6115 		rq_lock_irqsave(rq, &rf);
6116 		if (!cfs_rq_throttled(cfs_rq))
6117 			goto next;
6118 
6119 		/* Already queued for async unthrottle */
6120 		if (!list_empty(&cfs_rq->throttled_csd_list))
6121 			goto next;
6122 
6123 		/* By the above checks, this should never be true */
6124 		WARN_ON_ONCE(cfs_rq->runtime_remaining > 0);
6125 
6126 		raw_spin_lock(&cfs_b->lock);
6127 		runtime = -cfs_rq->runtime_remaining + 1;
6128 		if (runtime > cfs_b->runtime)
6129 			runtime = cfs_b->runtime;
6130 		cfs_b->runtime -= runtime;
6131 		remaining = cfs_b->runtime;
6132 		raw_spin_unlock(&cfs_b->lock);
6133 
6134 		cfs_rq->runtime_remaining += runtime;
6135 
6136 		/* we check whether we're throttled above */
6137 		if (cfs_rq->runtime_remaining > 0) {
6138 			if (cpu_of(rq) != this_cpu) {
6139 				unthrottle_cfs_rq_async(cfs_rq);
6140 			} else {
6141 				/*
6142 				 * We currently only expect to be unthrottling
6143 				 * a single cfs_rq locally.
6144 				 */
6145 				WARN_ON_ONCE(!list_empty(&local_unthrottle));
6146 				list_add_tail(&cfs_rq->throttled_csd_list,
6147 					      &local_unthrottle);
6148 			}
6149 		} else {
6150 			throttled = true;
6151 		}
6152 
6153 next:
6154 		rq_unlock_irqrestore(rq, &rf);
6155 	}
6156 
6157 	list_for_each_entry_safe(cfs_rq, tmp, &local_unthrottle,
6158 				 throttled_csd_list) {
6159 		struct rq *rq = rq_of(cfs_rq);
6160 
6161 		rq_lock_irqsave(rq, &rf);
6162 
6163 		list_del_init(&cfs_rq->throttled_csd_list);
6164 
6165 		if (cfs_rq_throttled(cfs_rq))
6166 			unthrottle_cfs_rq(cfs_rq);
6167 
6168 		rq_unlock_irqrestore(rq, &rf);
6169 	}
6170 	WARN_ON_ONCE(!list_empty(&local_unthrottle));
6171 
6172 	rcu_read_unlock();
6173 
6174 	return throttled;
6175 }
6176 
6177 /*
6178  * Responsible for refilling a task_group's bandwidth and unthrottling its
6179  * cfs_rqs as appropriate. If there has been no activity within the last
6180  * period the timer is deactivated until scheduling resumes; cfs_b->idle is
6181  * used to track this state.
6182  */
6183 static int do_sched_cfs_period_timer(struct cfs_bandwidth *cfs_b, int overrun, unsigned long flags)
6184 	__must_hold(&cfs_b->lock)
6185 {
6186 	int throttled;
6187 
6188 	/* no need to continue the timer with no bandwidth constraint */
6189 	if (cfs_b->quota == RUNTIME_INF)
6190 		goto out_deactivate;
6191 
6192 	throttled = !list_empty(&cfs_b->throttled_cfs_rq);
6193 	cfs_b->nr_periods += overrun;
6194 
6195 	/* Refill extra burst quota even if cfs_b->idle */
6196 	__refill_cfs_bandwidth_runtime(cfs_b);
6197 
6198 	/*
6199 	 * idle depends on !throttled (for the case of a large deficit), and if
6200 	 * we're going inactive then everything else can be deferred
6201 	 */
6202 	if (cfs_b->idle && !throttled)
6203 		goto out_deactivate;
6204 
6205 	if (!throttled) {
6206 		/* mark as potentially idle for the upcoming period */
6207 		cfs_b->idle = 1;
6208 		return 0;
6209 	}
6210 
6211 	/* account preceding periods in which throttling occurred */
6212 	cfs_b->nr_throttled += overrun;
6213 
6214 	/*
6215 	 * This check is repeated as we release cfs_b->lock while we unthrottle.
6216 	 */
6217 	while (throttled && cfs_b->runtime > 0) {
6218 		raw_spin_unlock_irqrestore(&cfs_b->lock, flags);
6219 		/* we can't nest cfs_b->lock while distributing bandwidth */
6220 		throttled = distribute_cfs_runtime(cfs_b);
6221 		raw_spin_lock_irqsave(&cfs_b->lock, flags);
6222 	}
6223 
6224 	/*
6225 	 * While we are ensured activity in the period following an
6226 	 * unthrottle, this also covers the case in which the new bandwidth is
6227 	 * insufficient to cover the existing bandwidth deficit.  (Forcing the
6228 	 * timer to remain active while there are any throttled entities.)
6229 	 */
6230 	cfs_b->idle = 0;
6231 
6232 	return 0;
6233 
6234 out_deactivate:
6235 	return 1;
6236 }
6237 
6238 /* a cfs_rq won't donate quota below this amount */
6239 static const u64 min_cfs_rq_runtime = 1 * NSEC_PER_MSEC;
6240 /* minimum remaining period time to redistribute slack quota */
6241 static const u64 min_bandwidth_expiration = 2 * NSEC_PER_MSEC;
6242 /* how long we wait to gather additional slack before distributing */
6243 static const u64 cfs_bandwidth_slack_period = 5 * NSEC_PER_MSEC;
6244 
6245 /*
6246  * Are we near the end of the current quota period?
6247  *
6248  * Requires cfs_b->lock for hrtimer_expires_remaining to be safe against the
6249  * hrtimer base being cleared by hrtimer_start. In the case of
6250  * migrate_hrtimers, base is never cleared, so we are fine.
6251  */
6252 static int runtime_refresh_within(struct cfs_bandwidth *cfs_b, u64 min_expire)
6253 {
6254 	struct hrtimer *refresh_timer = &cfs_b->period_timer;
6255 	s64 remaining;
6256 
6257 	/* if the call-back is running a quota refresh is already occurring */
6258 	if (hrtimer_callback_running(refresh_timer))
6259 		return 1;
6260 
6261 	/* is a quota refresh about to occur? */
6262 	remaining = ktime_to_ns(hrtimer_expires_remaining(refresh_timer));
6263 	if (remaining < (s64)min_expire)
6264 		return 1;
6265 
6266 	return 0;
6267 }
6268 
6269 static void start_cfs_slack_bandwidth(struct cfs_bandwidth *cfs_b)
6270 {
6271 	u64 min_left = cfs_bandwidth_slack_period + min_bandwidth_expiration;
6272 
6273 	/* if there's a quota refresh soon don't bother with slack */
6274 	if (runtime_refresh_within(cfs_b, min_left))
6275 		return;
6276 
6277 	/* don't push forwards an existing deferred unthrottle */
6278 	if (cfs_b->slack_started)
6279 		return;
6280 	cfs_b->slack_started = true;
6281 
6282 	hrtimer_start(&cfs_b->slack_timer,
6283 			ns_to_ktime(cfs_bandwidth_slack_period),
6284 			HRTIMER_MODE_REL);
6285 }
6286 
6287 /* we know any runtime found here is valid as update_curr() precedes return */
6288 static void __return_cfs_rq_runtime(struct cfs_rq *cfs_rq)
6289 {
6290 	struct cfs_bandwidth *cfs_b = tg_cfs_bandwidth(cfs_rq->tg);
6291 	s64 slack_runtime = cfs_rq->runtime_remaining - min_cfs_rq_runtime;
6292 
6293 	if (slack_runtime <= 0)
6294 		return;
6295 
6296 	raw_spin_lock(&cfs_b->lock);
6297 	if (cfs_b->quota != RUNTIME_INF) {
6298 		cfs_b->runtime += slack_runtime;
6299 
6300 		/* we are under rq->lock, defer unthrottling using a timer */
6301 		if (cfs_b->runtime > sched_cfs_bandwidth_slice() &&
6302 		    !list_empty(&cfs_b->throttled_cfs_rq))
6303 			start_cfs_slack_bandwidth(cfs_b);
6304 	}
6305 	raw_spin_unlock(&cfs_b->lock);
6306 
6307 	/* even if it's not valid for return we don't want to try again */
6308 	cfs_rq->runtime_remaining -= slack_runtime;
6309 }
6310 
6311 static __always_inline void return_cfs_rq_runtime(struct cfs_rq *cfs_rq)
6312 {
6313 	if (!cfs_bandwidth_used())
6314 		return;
6315 
6316 	if (!cfs_rq->runtime_enabled || cfs_rq->nr_queued)
6317 		return;
6318 
6319 	__return_cfs_rq_runtime(cfs_rq);
6320 }
6321 
6322 /*
6323  * This is done with a timer (instead of inline with bandwidth return) since
6324  * it's necessary to juggle rq->locks to unthrottle their respective cfs_rqs.
6325  */
6326 static void do_sched_cfs_slack_timer(struct cfs_bandwidth *cfs_b)
6327 {
6328 	u64 runtime = 0, slice = sched_cfs_bandwidth_slice();
6329 	unsigned long flags;
6330 
6331 	/* confirm we're still not at a refresh boundary */
6332 	raw_spin_lock_irqsave(&cfs_b->lock, flags);
6333 	cfs_b->slack_started = false;
6334 
6335 	if (runtime_refresh_within(cfs_b, min_bandwidth_expiration)) {
6336 		raw_spin_unlock_irqrestore(&cfs_b->lock, flags);
6337 		return;
6338 	}
6339 
6340 	if (cfs_b->quota != RUNTIME_INF && cfs_b->runtime > slice)
6341 		runtime = cfs_b->runtime;
6342 
6343 	raw_spin_unlock_irqrestore(&cfs_b->lock, flags);
6344 
6345 	if (!runtime)
6346 		return;
6347 
6348 	distribute_cfs_runtime(cfs_b);
6349 }
6350 
6351 /*
6352  * When a group wakes up we want to make sure that its quota is not already
6353  * expired/exceeded, otherwise it may be allowed to steal additional ticks of
6354  * runtime as update_curr() throttling can not trigger until it's on-rq.
6355  */
6356 static void check_enqueue_throttle(struct cfs_rq *cfs_rq)
6357 {
6358 	if (!cfs_bandwidth_used())
6359 		return;
6360 
6361 	/* an active group must be handled by the update_curr()->put() path */
6362 	if (!cfs_rq->runtime_enabled || cfs_rq->curr)
6363 		return;
6364 
6365 	/* ensure the group is not already throttled */
6366 	if (cfs_rq_throttled(cfs_rq))
6367 		return;
6368 
6369 	/* update runtime allocation */
6370 	account_cfs_rq_runtime(cfs_rq, 0);
6371 	if (cfs_rq->runtime_remaining <= 0)
6372 		throttle_cfs_rq(cfs_rq);
6373 }
6374 
6375 static void sync_throttle(struct task_group *tg, int cpu)
6376 {
6377 	struct cfs_rq *pcfs_rq, *cfs_rq;
6378 
6379 	if (!cfs_bandwidth_used())
6380 		return;
6381 
6382 	if (!tg->parent)
6383 		return;
6384 
6385 	cfs_rq = tg->cfs_rq[cpu];
6386 	pcfs_rq = tg->parent->cfs_rq[cpu];
6387 
6388 	cfs_rq->throttle_count = pcfs_rq->throttle_count;
6389 	cfs_rq->throttled_clock_pelt = rq_clock_pelt(cpu_rq(cpu));
6390 
6391 	/*
6392 	 * It is not enough to sync the "pelt_clock_throttled" indicator
6393 	 * with the parent cfs_rq when the hierarchy is not queued.
6394 	 * Always join a throttled hierarchy with PELT clock throttled
6395 	 * and leaf it to the first enqueue, or distribution to
6396 	 * unthrottle the PELT clock.
6397 	 */
6398 	if (cfs_rq->throttle_count)
6399 		cfs_rq->pelt_clock_throttled = 1;
6400 }
6401 
6402 /* conditionally throttle active cfs_rq's from put_prev_entity() */
6403 static bool check_cfs_rq_runtime(struct cfs_rq *cfs_rq)
6404 {
6405 	if (!cfs_bandwidth_used())
6406 		return false;
6407 
6408 	if (likely(!cfs_rq->runtime_enabled || cfs_rq->runtime_remaining > 0))
6409 		return false;
6410 
6411 	/*
6412 	 * it's possible for a throttled entity to be forced into a running
6413 	 * state (e.g. set_curr_task), in this case we're finished.
6414 	 */
6415 	if (cfs_rq_throttled(cfs_rq))
6416 		return true;
6417 
6418 	return throttle_cfs_rq(cfs_rq);
6419 }
6420 
6421 static enum hrtimer_restart sched_cfs_slack_timer(struct hrtimer *timer)
6422 {
6423 	struct cfs_bandwidth *cfs_b =
6424 		container_of(timer, struct cfs_bandwidth, slack_timer);
6425 
6426 	do_sched_cfs_slack_timer(cfs_b);
6427 
6428 	return HRTIMER_NORESTART;
6429 }
6430 
6431 static enum hrtimer_restart sched_cfs_period_timer(struct hrtimer *timer)
6432 {
6433 	struct cfs_bandwidth *cfs_b =
6434 		container_of(timer, struct cfs_bandwidth, period_timer);
6435 	unsigned long flags;
6436 	int overrun;
6437 	int idle = 0;
6438 	int count = 0;
6439 
6440 	raw_spin_lock_irqsave(&cfs_b->lock, flags);
6441 	for (;;) {
6442 		overrun = hrtimer_forward_now(timer, cfs_b->period);
6443 		if (!overrun)
6444 			break;
6445 
6446 		idle = do_sched_cfs_period_timer(cfs_b, overrun, flags);
6447 
6448 		if (++count > 3) {
6449 			u64 new, old = ktime_to_ns(cfs_b->period);
6450 
6451 			/*
6452 			 * Grow period by a factor of 2 to avoid losing precision.
6453 			 * Precision loss in the quota/period ratio can cause __cfs_schedulable
6454 			 * to fail.
6455 			 */
6456 			new = old * 2;
6457 			if (new < max_bw_quota_period_us * NSEC_PER_USEC) {
6458 				cfs_b->period = ns_to_ktime(new);
6459 				cfs_b->quota *= 2;
6460 				cfs_b->burst *= 2;
6461 
6462 				pr_warn_ratelimited(
6463 	"cfs_period_timer[cpu%d]: period too short, scaling up (new cfs_period_us = %lld, cfs_quota_us = %lld)\n",
6464 					smp_processor_id(),
6465 					div_u64(new, NSEC_PER_USEC),
6466 					div_u64(cfs_b->quota, NSEC_PER_USEC));
6467 			} else {
6468 				pr_warn_ratelimited(
6469 	"cfs_period_timer[cpu%d]: period too short, but cannot scale up without losing precision (cfs_period_us = %lld, cfs_quota_us = %lld)\n",
6470 					smp_processor_id(),
6471 					div_u64(old, NSEC_PER_USEC),
6472 					div_u64(cfs_b->quota, NSEC_PER_USEC));
6473 			}
6474 
6475 			/* reset count so we don't come right back in here */
6476 			count = 0;
6477 		}
6478 	}
6479 	if (idle)
6480 		cfs_b->period_active = 0;
6481 	raw_spin_unlock_irqrestore(&cfs_b->lock, flags);
6482 
6483 	return idle ? HRTIMER_NORESTART : HRTIMER_RESTART;
6484 }
6485 
6486 void init_cfs_bandwidth(struct cfs_bandwidth *cfs_b, struct cfs_bandwidth *parent)
6487 {
6488 	raw_spin_lock_init(&cfs_b->lock);
6489 	cfs_b->runtime = 0;
6490 	cfs_b->quota = RUNTIME_INF;
6491 	cfs_b->period = us_to_ktime(default_bw_period_us());
6492 	cfs_b->burst = 0;
6493 	cfs_b->hierarchical_quota = parent ? parent->hierarchical_quota : RUNTIME_INF;
6494 
6495 	INIT_LIST_HEAD(&cfs_b->throttled_cfs_rq);
6496 	hrtimer_setup(&cfs_b->period_timer, sched_cfs_period_timer, CLOCK_MONOTONIC,
6497 		      HRTIMER_MODE_ABS_PINNED);
6498 
6499 	/* Add a random offset so that timers interleave */
6500 	hrtimer_set_expires(&cfs_b->period_timer,
6501 			    get_random_u32_below(cfs_b->period));
6502 	hrtimer_setup(&cfs_b->slack_timer, sched_cfs_slack_timer, CLOCK_MONOTONIC,
6503 		      HRTIMER_MODE_REL);
6504 	cfs_b->slack_started = false;
6505 }
6506 
6507 static void init_cfs_rq_runtime(struct cfs_rq *cfs_rq)
6508 {
6509 	cfs_rq->runtime_enabled = 0;
6510 	INIT_LIST_HEAD(&cfs_rq->throttled_list);
6511 	INIT_LIST_HEAD(&cfs_rq->throttled_csd_list);
6512 	INIT_LIST_HEAD(&cfs_rq->throttled_limbo_list);
6513 }
6514 
6515 void start_cfs_bandwidth(struct cfs_bandwidth *cfs_b)
6516 {
6517 	lockdep_assert_held(&cfs_b->lock);
6518 
6519 	if (cfs_b->period_active)
6520 		return;
6521 
6522 	cfs_b->period_active = 1;
6523 	hrtimer_forward_now(&cfs_b->period_timer, cfs_b->period);
6524 	hrtimer_start_expires(&cfs_b->period_timer, HRTIMER_MODE_ABS_PINNED);
6525 }
6526 
6527 static void destroy_cfs_bandwidth(struct cfs_bandwidth *cfs_b)
6528 {
6529 	int __maybe_unused i;
6530 
6531 	/* init_cfs_bandwidth() was not called */
6532 	if (!cfs_b->throttled_cfs_rq.next)
6533 		return;
6534 
6535 	hrtimer_cancel(&cfs_b->period_timer);
6536 	hrtimer_cancel(&cfs_b->slack_timer);
6537 
6538 	/*
6539 	 * It is possible that we still have some cfs_rq's pending on a CSD
6540 	 * list, though this race is very rare. In order for this to occur, we
6541 	 * must have raced with the last task leaving the group while there
6542 	 * exist throttled cfs_rq(s), and the period_timer must have queued the
6543 	 * CSD item but the remote cpu has not yet processed it. To handle this,
6544 	 * we can simply flush all pending CSD work inline here. We're
6545 	 * guaranteed at this point that no additional cfs_rq of this group can
6546 	 * join a CSD list.
6547 	 */
6548 	for_each_possible_cpu(i) {
6549 		struct rq *rq = cpu_rq(i);
6550 		unsigned long flags;
6551 
6552 		if (list_empty(&rq->cfsb_csd_list))
6553 			continue;
6554 
6555 		local_irq_save(flags);
6556 		__cfsb_csd_unthrottle(rq);
6557 		local_irq_restore(flags);
6558 	}
6559 }
6560 
6561 /*
6562  * Both these CPU hotplug callbacks race against unregister_fair_sched_group()
6563  *
6564  * The race is harmless, since modifying bandwidth settings of unhooked group
6565  * bits doesn't do much.
6566  */
6567 
6568 /* cpu online callback */
6569 static void __maybe_unused update_runtime_enabled(struct rq *rq)
6570 {
6571 	struct task_group *tg;
6572 
6573 	lockdep_assert_rq_held(rq);
6574 
6575 	rcu_read_lock();
6576 	list_for_each_entry_rcu(tg, &task_groups, list) {
6577 		struct cfs_bandwidth *cfs_b = &tg->cfs_bandwidth;
6578 		struct cfs_rq *cfs_rq = tg->cfs_rq[cpu_of(rq)];
6579 
6580 		raw_spin_lock(&cfs_b->lock);
6581 		cfs_rq->runtime_enabled = cfs_b->quota != RUNTIME_INF;
6582 		raw_spin_unlock(&cfs_b->lock);
6583 	}
6584 	rcu_read_unlock();
6585 }
6586 
6587 /* cpu offline callback */
6588 static void __maybe_unused unthrottle_offline_cfs_rqs(struct rq *rq)
6589 {
6590 	struct task_group *tg;
6591 
6592 	lockdep_assert_rq_held(rq);
6593 
6594 	// Do not unthrottle for an active CPU
6595 	if (cpumask_test_cpu(cpu_of(rq), cpu_active_mask))
6596 		return;
6597 
6598 	/*
6599 	 * The rq clock has already been updated in the
6600 	 * set_rq_offline(), so we should skip updating
6601 	 * the rq clock again in unthrottle_cfs_rq().
6602 	 */
6603 	rq_clock_start_loop_update(rq);
6604 
6605 	rcu_read_lock();
6606 	list_for_each_entry_rcu(tg, &task_groups, list) {
6607 		struct cfs_rq *cfs_rq = tg->cfs_rq[cpu_of(rq)];
6608 
6609 		if (!cfs_rq->runtime_enabled)
6610 			continue;
6611 
6612 		/*
6613 		 * Offline rq is schedulable till CPU is completely disabled
6614 		 * in take_cpu_down(), so we prevent new cfs throttling here.
6615 		 */
6616 		cfs_rq->runtime_enabled = 0;
6617 
6618 		if (!cfs_rq_throttled(cfs_rq))
6619 			continue;
6620 
6621 		/*
6622 		 * clock_task is not advancing so we just need to make sure
6623 		 * there's some valid quota amount
6624 		 */
6625 		cfs_rq->runtime_remaining = 1;
6626 		unthrottle_cfs_rq(cfs_rq);
6627 	}
6628 	rcu_read_unlock();
6629 
6630 	rq_clock_stop_loop_update(rq);
6631 }
6632 
6633 bool cfs_task_bw_constrained(struct task_struct *p)
6634 {
6635 	struct cfs_rq *cfs_rq = task_cfs_rq(p);
6636 
6637 	if (!cfs_bandwidth_used())
6638 		return false;
6639 
6640 	if (cfs_rq->runtime_enabled ||
6641 	    tg_cfs_bandwidth(cfs_rq->tg)->hierarchical_quota != RUNTIME_INF)
6642 		return true;
6643 
6644 	return false;
6645 }
6646 
6647 #ifdef CONFIG_NO_HZ_FULL
6648 /* called from pick_next_task_fair() */
6649 static void sched_fair_update_stop_tick(struct rq *rq, struct task_struct *p)
6650 {
6651 	int cpu = cpu_of(rq);
6652 
6653 	if (!cfs_bandwidth_used())
6654 		return;
6655 
6656 	if (!tick_nohz_full_cpu(cpu))
6657 		return;
6658 
6659 	if (rq->nr_running != 1)
6660 		return;
6661 
6662 	/*
6663 	 *  We know there is only one task runnable and we've just picked it. The
6664 	 *  normal enqueue path will have cleared TICK_DEP_BIT_SCHED if we will
6665 	 *  be otherwise able to stop the tick. Just need to check if we are using
6666 	 *  bandwidth control.
6667 	 */
6668 	if (cfs_task_bw_constrained(p))
6669 		tick_nohz_dep_set_cpu(cpu, TICK_DEP_BIT_SCHED);
6670 }
6671 #endif /* CONFIG_NO_HZ_FULL */
6672 
6673 #else /* !CONFIG_CFS_BANDWIDTH: */
6674 
6675 static void account_cfs_rq_runtime(struct cfs_rq *cfs_rq, u64 delta_exec) {}
6676 static bool check_cfs_rq_runtime(struct cfs_rq *cfs_rq) { return false; }
6677 static void check_enqueue_throttle(struct cfs_rq *cfs_rq) {}
6678 static inline void sync_throttle(struct task_group *tg, int cpu) {}
6679 static __always_inline void return_cfs_rq_runtime(struct cfs_rq *cfs_rq) {}
6680 static void task_throttle_setup_work(struct task_struct *p) {}
6681 static bool task_is_throttled(struct task_struct *p) { return false; }
6682 static void dequeue_throttled_task(struct task_struct *p, int flags) {}
6683 static bool enqueue_throttled_task(struct task_struct *p) { return false; }
6684 static void record_throttle_clock(struct cfs_rq *cfs_rq) {}
6685 
6686 static inline int cfs_rq_throttled(struct cfs_rq *cfs_rq)
6687 {
6688 	return 0;
6689 }
6690 
6691 static inline bool cfs_rq_pelt_clock_throttled(struct cfs_rq *cfs_rq)
6692 {
6693 	return false;
6694 }
6695 
6696 static inline int throttled_hierarchy(struct cfs_rq *cfs_rq)
6697 {
6698 	return 0;
6699 }
6700 
6701 static inline int lb_throttled_hierarchy(struct task_struct *p, int dst_cpu)
6702 {
6703 	return 0;
6704 }
6705 
6706 #ifdef CONFIG_FAIR_GROUP_SCHED
6707 void init_cfs_bandwidth(struct cfs_bandwidth *cfs_b, struct cfs_bandwidth *parent) {}
6708 static void init_cfs_rq_runtime(struct cfs_rq *cfs_rq) {}
6709 #endif
6710 
6711 static inline struct cfs_bandwidth *tg_cfs_bandwidth(struct task_group *tg)
6712 {
6713 	return NULL;
6714 }
6715 static inline void destroy_cfs_bandwidth(struct cfs_bandwidth *cfs_b) {}
6716 static inline void update_runtime_enabled(struct rq *rq) {}
6717 static inline void unthrottle_offline_cfs_rqs(struct rq *rq) {}
6718 #ifdef CONFIG_CGROUP_SCHED
6719 bool cfs_task_bw_constrained(struct task_struct *p)
6720 {
6721 	return false;
6722 }
6723 #endif
6724 #endif /* !CONFIG_CFS_BANDWIDTH */
6725 
6726 #if !defined(CONFIG_CFS_BANDWIDTH) || !defined(CONFIG_NO_HZ_FULL)
6727 static inline void sched_fair_update_stop_tick(struct rq *rq, struct task_struct *p) {}
6728 #endif
6729 
6730 /**************************************************
6731  * CFS operations on tasks:
6732  */
6733 
6734 #ifdef CONFIG_SCHED_HRTICK
6735 static void hrtick_start_fair(struct rq *rq, struct task_struct *p)
6736 {
6737 	struct sched_entity *se = &p->se;
6738 
6739 	WARN_ON_ONCE(task_rq(p) != rq);
6740 
6741 	if (rq->cfs.h_nr_queued > 1) {
6742 		u64 ran = se->sum_exec_runtime - se->prev_sum_exec_runtime;
6743 		u64 slice = se->slice;
6744 		s64 delta = slice - ran;
6745 
6746 		if (delta < 0) {
6747 			if (task_current_donor(rq, p))
6748 				resched_curr(rq);
6749 			return;
6750 		}
6751 		hrtick_start(rq, delta);
6752 	}
6753 }
6754 
6755 /*
6756  * called from enqueue/dequeue and updates the hrtick when the
6757  * current task is from our class and nr_running is low enough
6758  * to matter.
6759  */
6760 static void hrtick_update(struct rq *rq)
6761 {
6762 	struct task_struct *donor = rq->donor;
6763 
6764 	if (!hrtick_enabled_fair(rq) || donor->sched_class != &fair_sched_class)
6765 		return;
6766 
6767 	hrtick_start_fair(rq, donor);
6768 }
6769 #else /* !CONFIG_SCHED_HRTICK: */
6770 static inline void
6771 hrtick_start_fair(struct rq *rq, struct task_struct *p)
6772 {
6773 }
6774 
6775 static inline void hrtick_update(struct rq *rq)
6776 {
6777 }
6778 #endif /* !CONFIG_SCHED_HRTICK */
6779 
6780 static inline bool cpu_overutilized(int cpu)
6781 {
6782 	unsigned long  rq_util_min, rq_util_max;
6783 
6784 	if (!sched_energy_enabled())
6785 		return false;
6786 
6787 	rq_util_min = uclamp_rq_get(cpu_rq(cpu), UCLAMP_MIN);
6788 	rq_util_max = uclamp_rq_get(cpu_rq(cpu), UCLAMP_MAX);
6789 
6790 	/* Return true only if the utilization doesn't fit CPU's capacity */
6791 	return !util_fits_cpu(cpu_util_cfs(cpu), rq_util_min, rq_util_max, cpu);
6792 }
6793 
6794 /*
6795  * overutilized value make sense only if EAS is enabled
6796  */
6797 static inline bool is_rd_overutilized(struct root_domain *rd)
6798 {
6799 	return !sched_energy_enabled() || READ_ONCE(rd->overutilized);
6800 }
6801 
6802 static inline void set_rd_overutilized(struct root_domain *rd, bool flag)
6803 {
6804 	if (!sched_energy_enabled())
6805 		return;
6806 
6807 	WRITE_ONCE(rd->overutilized, flag);
6808 	trace_sched_overutilized_tp(rd, flag);
6809 }
6810 
6811 static inline void check_update_overutilized_status(struct rq *rq)
6812 {
6813 	/*
6814 	 * overutilized field is used for load balancing decisions only
6815 	 * if energy aware scheduler is being used
6816 	 */
6817 
6818 	if (!is_rd_overutilized(rq->rd) && cpu_overutilized(rq->cpu))
6819 		set_rd_overutilized(rq->rd, 1);
6820 }
6821 
6822 /* Runqueue only has SCHED_IDLE tasks enqueued */
6823 static int sched_idle_rq(struct rq *rq)
6824 {
6825 	return unlikely(rq->nr_running == rq->cfs.h_nr_idle &&
6826 			rq->nr_running);
6827 }
6828 
6829 static int sched_idle_cpu(int cpu)
6830 {
6831 	return sched_idle_rq(cpu_rq(cpu));
6832 }
6833 
6834 static void
6835 requeue_delayed_entity(struct sched_entity *se)
6836 {
6837 	struct cfs_rq *cfs_rq = cfs_rq_of(se);
6838 
6839 	/*
6840 	 * se->sched_delayed should imply: se->on_rq == 1.
6841 	 * Because a delayed entity is one that is still on
6842 	 * the runqueue competing until elegibility.
6843 	 */
6844 	WARN_ON_ONCE(!se->sched_delayed);
6845 	WARN_ON_ONCE(!se->on_rq);
6846 
6847 	if (sched_feat(DELAY_ZERO)) {
6848 		update_entity_lag(cfs_rq, se);
6849 		if (se->vlag > 0) {
6850 			cfs_rq->nr_queued--;
6851 			if (se != cfs_rq->curr)
6852 				__dequeue_entity(cfs_rq, se);
6853 			se->vlag = 0;
6854 			place_entity(cfs_rq, se, 0);
6855 			if (se != cfs_rq->curr)
6856 				__enqueue_entity(cfs_rq, se);
6857 			cfs_rq->nr_queued++;
6858 		}
6859 	}
6860 
6861 	update_load_avg(cfs_rq, se, 0);
6862 	clear_delayed(se);
6863 }
6864 
6865 /*
6866  * The enqueue_task method is called before nr_running is
6867  * increased. Here we update the fair scheduling stats and
6868  * then put the task into the rbtree:
6869  */
6870 static void
6871 enqueue_task_fair(struct rq *rq, struct task_struct *p, int flags)
6872 {
6873 	struct cfs_rq *cfs_rq;
6874 	struct sched_entity *se = &p->se;
6875 	int h_nr_idle = task_has_idle_policy(p);
6876 	int h_nr_runnable = 1;
6877 	int task_new = !(flags & ENQUEUE_WAKEUP);
6878 	int rq_h_nr_queued = rq->cfs.h_nr_queued;
6879 	u64 slice = 0;
6880 
6881 	if (task_is_throttled(p) && enqueue_throttled_task(p))
6882 		return;
6883 
6884 	/*
6885 	 * The code below (indirectly) updates schedutil which looks at
6886 	 * the cfs_rq utilization to select a frequency.
6887 	 * Let's add the task's estimated utilization to the cfs_rq's
6888 	 * estimated utilization, before we update schedutil.
6889 	 */
6890 	if (!p->se.sched_delayed || (flags & ENQUEUE_DELAYED))
6891 		util_est_enqueue(&rq->cfs, p);
6892 
6893 	if (flags & ENQUEUE_DELAYED) {
6894 		requeue_delayed_entity(se);
6895 		return;
6896 	}
6897 
6898 	/*
6899 	 * If in_iowait is set, the code below may not trigger any cpufreq
6900 	 * utilization updates, so do it here explicitly with the IOWAIT flag
6901 	 * passed.
6902 	 */
6903 	if (p->in_iowait)
6904 		cpufreq_update_util(rq, SCHED_CPUFREQ_IOWAIT);
6905 
6906 	if (task_new && se->sched_delayed)
6907 		h_nr_runnable = 0;
6908 
6909 	for_each_sched_entity(se) {
6910 		if (se->on_rq) {
6911 			if (se->sched_delayed)
6912 				requeue_delayed_entity(se);
6913 			break;
6914 		}
6915 		cfs_rq = cfs_rq_of(se);
6916 
6917 		/*
6918 		 * Basically set the slice of group entries to the min_slice of
6919 		 * their respective cfs_rq. This ensures the group can service
6920 		 * its entities in the desired time-frame.
6921 		 */
6922 		if (slice) {
6923 			se->slice = slice;
6924 			se->custom_slice = 1;
6925 		}
6926 		enqueue_entity(cfs_rq, se, flags);
6927 		slice = cfs_rq_min_slice(cfs_rq);
6928 
6929 		cfs_rq->h_nr_runnable += h_nr_runnable;
6930 		cfs_rq->h_nr_queued++;
6931 		cfs_rq->h_nr_idle += h_nr_idle;
6932 
6933 		if (cfs_rq_is_idle(cfs_rq))
6934 			h_nr_idle = 1;
6935 
6936 		flags = ENQUEUE_WAKEUP;
6937 	}
6938 
6939 	for_each_sched_entity(se) {
6940 		cfs_rq = cfs_rq_of(se);
6941 
6942 		update_load_avg(cfs_rq, se, UPDATE_TG);
6943 		se_update_runnable(se);
6944 		update_cfs_group(se);
6945 
6946 		se->slice = slice;
6947 		if (se != cfs_rq->curr)
6948 			min_vruntime_cb_propagate(&se->run_node, NULL);
6949 		slice = cfs_rq_min_slice(cfs_rq);
6950 
6951 		cfs_rq->h_nr_runnable += h_nr_runnable;
6952 		cfs_rq->h_nr_queued++;
6953 		cfs_rq->h_nr_idle += h_nr_idle;
6954 
6955 		if (cfs_rq_is_idle(cfs_rq))
6956 			h_nr_idle = 1;
6957 	}
6958 
6959 	if (!rq_h_nr_queued && rq->cfs.h_nr_queued)
6960 		dl_server_start(&rq->fair_server);
6961 
6962 	/* At this point se is NULL and we are at root level*/
6963 	add_nr_running(rq, 1);
6964 
6965 	/*
6966 	 * Since new tasks are assigned an initial util_avg equal to
6967 	 * half of the spare capacity of their CPU, tiny tasks have the
6968 	 * ability to cross the overutilized threshold, which will
6969 	 * result in the load balancer ruining all the task placement
6970 	 * done by EAS. As a way to mitigate that effect, do not account
6971 	 * for the first enqueue operation of new tasks during the
6972 	 * overutilized flag detection.
6973 	 *
6974 	 * A better way of solving this problem would be to wait for
6975 	 * the PELT signals of tasks to converge before taking them
6976 	 * into account, but that is not straightforward to implement,
6977 	 * and the following generally works well enough in practice.
6978 	 */
6979 	if (!task_new)
6980 		check_update_overutilized_status(rq);
6981 
6982 	assert_list_leaf_cfs_rq(rq);
6983 
6984 	hrtick_update(rq);
6985 }
6986 
6987 /*
6988  * Basically dequeue_task_fair(), except it can deal with dequeue_entity()
6989  * failing half-way through and resume the dequeue later.
6990  *
6991  * Returns:
6992  * -1 - dequeue delayed
6993  *  0 - dequeue throttled
6994  *  1 - dequeue complete
6995  */
6996 static int dequeue_entities(struct rq *rq, struct sched_entity *se, int flags)
6997 {
6998 	bool was_sched_idle = sched_idle_rq(rq);
6999 	bool task_sleep = flags & DEQUEUE_SLEEP;
7000 	bool task_delayed = flags & DEQUEUE_DELAYED;
7001 	bool task_throttled = flags & DEQUEUE_THROTTLE;
7002 	struct task_struct *p = NULL;
7003 	int h_nr_idle = 0;
7004 	int h_nr_queued = 0;
7005 	int h_nr_runnable = 0;
7006 	struct cfs_rq *cfs_rq;
7007 	u64 slice = 0;
7008 
7009 	if (entity_is_task(se)) {
7010 		p = task_of(se);
7011 		h_nr_queued = 1;
7012 		h_nr_idle = task_has_idle_policy(p);
7013 		if (task_sleep || task_delayed || !se->sched_delayed)
7014 			h_nr_runnable = 1;
7015 	}
7016 
7017 	for_each_sched_entity(se) {
7018 		cfs_rq = cfs_rq_of(se);
7019 
7020 		if (!dequeue_entity(cfs_rq, se, flags)) {
7021 			if (p && &p->se == se)
7022 				return -1;
7023 
7024 			slice = cfs_rq_min_slice(cfs_rq);
7025 			break;
7026 		}
7027 
7028 		cfs_rq->h_nr_runnable -= h_nr_runnable;
7029 		cfs_rq->h_nr_queued -= h_nr_queued;
7030 		cfs_rq->h_nr_idle -= h_nr_idle;
7031 
7032 		if (cfs_rq_is_idle(cfs_rq))
7033 			h_nr_idle = h_nr_queued;
7034 
7035 		if (throttled_hierarchy(cfs_rq) && task_throttled)
7036 			record_throttle_clock(cfs_rq);
7037 
7038 		/* Don't dequeue parent if it has other entities besides us */
7039 		if (cfs_rq->load.weight) {
7040 			slice = cfs_rq_min_slice(cfs_rq);
7041 
7042 			/* Avoid re-evaluating load for this entity: */
7043 			se = parent_entity(se);
7044 			/*
7045 			 * Bias pick_next to pick a task from this cfs_rq, as
7046 			 * p is sleeping when it is within its sched_slice.
7047 			 */
7048 			if (task_sleep && se)
7049 				set_next_buddy(se);
7050 			break;
7051 		}
7052 		flags |= DEQUEUE_SLEEP;
7053 		flags &= ~(DEQUEUE_DELAYED | DEQUEUE_SPECIAL);
7054 	}
7055 
7056 	for_each_sched_entity(se) {
7057 		cfs_rq = cfs_rq_of(se);
7058 
7059 		update_load_avg(cfs_rq, se, UPDATE_TG);
7060 		se_update_runnable(se);
7061 		update_cfs_group(se);
7062 
7063 		se->slice = slice;
7064 		if (se != cfs_rq->curr)
7065 			min_vruntime_cb_propagate(&se->run_node, NULL);
7066 		slice = cfs_rq_min_slice(cfs_rq);
7067 
7068 		cfs_rq->h_nr_runnable -= h_nr_runnable;
7069 		cfs_rq->h_nr_queued -= h_nr_queued;
7070 		cfs_rq->h_nr_idle -= h_nr_idle;
7071 
7072 		if (cfs_rq_is_idle(cfs_rq))
7073 			h_nr_idle = h_nr_queued;
7074 
7075 		if (throttled_hierarchy(cfs_rq) && task_throttled)
7076 			record_throttle_clock(cfs_rq);
7077 	}
7078 
7079 	sub_nr_running(rq, h_nr_queued);
7080 
7081 	/* balance early to pull high priority tasks */
7082 	if (unlikely(!was_sched_idle && sched_idle_rq(rq)))
7083 		rq->next_balance = jiffies;
7084 
7085 	if (p && task_delayed) {
7086 		WARN_ON_ONCE(!task_sleep);
7087 		WARN_ON_ONCE(p->on_rq != 1);
7088 
7089 		/* Fix-up what dequeue_task_fair() skipped */
7090 		hrtick_update(rq);
7091 
7092 		/*
7093 		 * Fix-up what block_task() skipped.
7094 		 *
7095 		 * Must be last, @p might not be valid after this.
7096 		 */
7097 		__block_task(rq, p);
7098 	}
7099 
7100 	return 1;
7101 }
7102 
7103 /*
7104  * The dequeue_task method is called before nr_running is
7105  * decreased. We remove the task from the rbtree and
7106  * update the fair scheduling stats:
7107  */
7108 static bool dequeue_task_fair(struct rq *rq, struct task_struct *p, int flags)
7109 {
7110 	if (task_is_throttled(p)) {
7111 		dequeue_throttled_task(p, flags);
7112 		return true;
7113 	}
7114 
7115 	if (!p->se.sched_delayed)
7116 		util_est_dequeue(&rq->cfs, p);
7117 
7118 	util_est_update(&rq->cfs, p, flags & DEQUEUE_SLEEP);
7119 	if (dequeue_entities(rq, &p->se, flags) < 0)
7120 		return false;
7121 
7122 	/*
7123 	 * Must not reference @p after dequeue_entities(DEQUEUE_DELAYED).
7124 	 */
7125 
7126 	hrtick_update(rq);
7127 	return true;
7128 }
7129 
7130 static inline unsigned int cfs_h_nr_delayed(struct rq *rq)
7131 {
7132 	return (rq->cfs.h_nr_queued - rq->cfs.h_nr_runnable);
7133 }
7134 
7135 /* Working cpumask for: sched_balance_rq(), sched_balance_newidle(). */
7136 static DEFINE_PER_CPU(cpumask_var_t, load_balance_mask);
7137 static DEFINE_PER_CPU(cpumask_var_t, select_rq_mask);
7138 static DEFINE_PER_CPU(cpumask_var_t, should_we_balance_tmpmask);
7139 
7140 #ifdef CONFIG_NO_HZ_COMMON
7141 
7142 static struct {
7143 	cpumask_var_t idle_cpus_mask;
7144 	int has_blocked_load;		/* Idle CPUS has blocked load */
7145 	int needs_update;		/* Newly idle CPUs need their next_balance collated */
7146 	unsigned long next_balance;     /* in jiffy units */
7147 	unsigned long next_blocked;	/* Next update of blocked load in jiffies */
7148 } nohz ____cacheline_aligned;
7149 
7150 #endif /* CONFIG_NO_HZ_COMMON */
7151 
7152 static unsigned long cpu_load(struct rq *rq)
7153 {
7154 	return cfs_rq_load_avg(&rq->cfs);
7155 }
7156 
7157 /*
7158  * cpu_load_without - compute CPU load without any contributions from *p
7159  * @cpu: the CPU which load is requested
7160  * @p: the task which load should be discounted
7161  *
7162  * The load of a CPU is defined by the load of tasks currently enqueued on that
7163  * CPU as well as tasks which are currently sleeping after an execution on that
7164  * CPU.
7165  *
7166  * This method returns the load of the specified CPU by discounting the load of
7167  * the specified task, whenever the task is currently contributing to the CPU
7168  * load.
7169  */
7170 static unsigned long cpu_load_without(struct rq *rq, struct task_struct *p)
7171 {
7172 	struct cfs_rq *cfs_rq;
7173 	unsigned int load;
7174 
7175 	/* Task has no contribution or is new */
7176 	if (cpu_of(rq) != task_cpu(p) || !READ_ONCE(p->se.avg.last_update_time))
7177 		return cpu_load(rq);
7178 
7179 	cfs_rq = &rq->cfs;
7180 	load = READ_ONCE(cfs_rq->avg.load_avg);
7181 
7182 	/* Discount task's util from CPU's util */
7183 	lsub_positive(&load, task_h_load(p));
7184 
7185 	return load;
7186 }
7187 
7188 static unsigned long cpu_runnable(struct rq *rq)
7189 {
7190 	return cfs_rq_runnable_avg(&rq->cfs);
7191 }
7192 
7193 static unsigned long cpu_runnable_without(struct rq *rq, struct task_struct *p)
7194 {
7195 	struct cfs_rq *cfs_rq;
7196 	unsigned int runnable;
7197 
7198 	/* Task has no contribution or is new */
7199 	if (cpu_of(rq) != task_cpu(p) || !READ_ONCE(p->se.avg.last_update_time))
7200 		return cpu_runnable(rq);
7201 
7202 	cfs_rq = &rq->cfs;
7203 	runnable = READ_ONCE(cfs_rq->avg.runnable_avg);
7204 
7205 	/* Discount task's runnable from CPU's runnable */
7206 	lsub_positive(&runnable, p->se.avg.runnable_avg);
7207 
7208 	return runnable;
7209 }
7210 
7211 static unsigned long capacity_of(int cpu)
7212 {
7213 	return cpu_rq(cpu)->cpu_capacity;
7214 }
7215 
7216 static void record_wakee(struct task_struct *p)
7217 {
7218 	/*
7219 	 * Only decay a single time; tasks that have less then 1 wakeup per
7220 	 * jiffy will not have built up many flips.
7221 	 */
7222 	if (time_after(jiffies, current->wakee_flip_decay_ts + HZ)) {
7223 		current->wakee_flips >>= 1;
7224 		current->wakee_flip_decay_ts = jiffies;
7225 	}
7226 
7227 	if (current->last_wakee != p) {
7228 		current->last_wakee = p;
7229 		current->wakee_flips++;
7230 	}
7231 }
7232 
7233 /*
7234  * Detect M:N waker/wakee relationships via a switching-frequency heuristic.
7235  *
7236  * A waker of many should wake a different task than the one last awakened
7237  * at a frequency roughly N times higher than one of its wakees.
7238  *
7239  * In order to determine whether we should let the load spread vs consolidating
7240  * to shared cache, we look for a minimum 'flip' frequency of llc_size in one
7241  * partner, and a factor of lls_size higher frequency in the other.
7242  *
7243  * With both conditions met, we can be relatively sure that the relationship is
7244  * non-monogamous, with partner count exceeding socket size.
7245  *
7246  * Waker/wakee being client/server, worker/dispatcher, interrupt source or
7247  * whatever is irrelevant, spread criteria is apparent partner count exceeds
7248  * socket size.
7249  */
7250 static int wake_wide(struct task_struct *p)
7251 {
7252 	unsigned int master = current->wakee_flips;
7253 	unsigned int slave = p->wakee_flips;
7254 	int factor = __this_cpu_read(sd_llc_size);
7255 
7256 	if (master < slave)
7257 		swap(master, slave);
7258 	if (slave < factor || master < slave * factor)
7259 		return 0;
7260 	return 1;
7261 }
7262 
7263 /*
7264  * The purpose of wake_affine() is to quickly determine on which CPU we can run
7265  * soonest. For the purpose of speed we only consider the waking and previous
7266  * CPU.
7267  *
7268  * wake_affine_idle() - only considers 'now', it check if the waking CPU is
7269  *			cache-affine and is (or	will be) idle.
7270  *
7271  * wake_affine_weight() - considers the weight to reflect the average
7272  *			  scheduling latency of the CPUs. This seems to work
7273  *			  for the overloaded case.
7274  */
7275 static int
7276 wake_affine_idle(int this_cpu, int prev_cpu, int sync)
7277 {
7278 	/*
7279 	 * If this_cpu is idle, it implies the wakeup is from interrupt
7280 	 * context. Only allow the move if cache is shared. Otherwise an
7281 	 * interrupt intensive workload could force all tasks onto one
7282 	 * node depending on the IO topology or IRQ affinity settings.
7283 	 *
7284 	 * If the prev_cpu is idle and cache affine then avoid a migration.
7285 	 * There is no guarantee that the cache hot data from an interrupt
7286 	 * is more important than cache hot data on the prev_cpu and from
7287 	 * a cpufreq perspective, it's better to have higher utilisation
7288 	 * on one CPU.
7289 	 */
7290 	if (available_idle_cpu(this_cpu) && cpus_share_cache(this_cpu, prev_cpu))
7291 		return available_idle_cpu(prev_cpu) ? prev_cpu : this_cpu;
7292 
7293 	if (sync) {
7294 		struct rq *rq = cpu_rq(this_cpu);
7295 
7296 		if ((rq->nr_running - cfs_h_nr_delayed(rq)) == 1)
7297 			return this_cpu;
7298 	}
7299 
7300 	if (available_idle_cpu(prev_cpu))
7301 		return prev_cpu;
7302 
7303 	return nr_cpumask_bits;
7304 }
7305 
7306 static int
7307 wake_affine_weight(struct sched_domain *sd, struct task_struct *p,
7308 		   int this_cpu, int prev_cpu, int sync)
7309 {
7310 	s64 this_eff_load, prev_eff_load;
7311 	unsigned long task_load;
7312 
7313 	this_eff_load = cpu_load(cpu_rq(this_cpu));
7314 
7315 	if (sync) {
7316 		unsigned long current_load = task_h_load(current);
7317 
7318 		if (current_load > this_eff_load)
7319 			return this_cpu;
7320 
7321 		this_eff_load -= current_load;
7322 	}
7323 
7324 	task_load = task_h_load(p);
7325 
7326 	this_eff_load += task_load;
7327 	if (sched_feat(WA_BIAS))
7328 		this_eff_load *= 100;
7329 	this_eff_load *= capacity_of(prev_cpu);
7330 
7331 	prev_eff_load = cpu_load(cpu_rq(prev_cpu));
7332 	prev_eff_load -= task_load;
7333 	if (sched_feat(WA_BIAS))
7334 		prev_eff_load *= 100 + (sd->imbalance_pct - 100) / 2;
7335 	prev_eff_load *= capacity_of(this_cpu);
7336 
7337 	/*
7338 	 * If sync, adjust the weight of prev_eff_load such that if
7339 	 * prev_eff == this_eff that select_idle_sibling() will consider
7340 	 * stacking the wakee on top of the waker if no other CPU is
7341 	 * idle.
7342 	 */
7343 	if (sync)
7344 		prev_eff_load += 1;
7345 
7346 	return this_eff_load < prev_eff_load ? this_cpu : nr_cpumask_bits;
7347 }
7348 
7349 static int wake_affine(struct sched_domain *sd, struct task_struct *p,
7350 		       int this_cpu, int prev_cpu, int sync)
7351 {
7352 	int target = nr_cpumask_bits;
7353 
7354 	if (sched_feat(WA_IDLE))
7355 		target = wake_affine_idle(this_cpu, prev_cpu, sync);
7356 
7357 	if (sched_feat(WA_WEIGHT) && target == nr_cpumask_bits)
7358 		target = wake_affine_weight(sd, p, this_cpu, prev_cpu, sync);
7359 
7360 	schedstat_inc(p->stats.nr_wakeups_affine_attempts);
7361 	if (target != this_cpu)
7362 		return prev_cpu;
7363 
7364 	schedstat_inc(sd->ttwu_move_affine);
7365 	schedstat_inc(p->stats.nr_wakeups_affine);
7366 	return target;
7367 }
7368 
7369 static struct sched_group *
7370 sched_balance_find_dst_group(struct sched_domain *sd, struct task_struct *p, int this_cpu);
7371 
7372 /*
7373  * sched_balance_find_dst_group_cpu - find the idlest CPU among the CPUs in the group.
7374  */
7375 static int
7376 sched_balance_find_dst_group_cpu(struct sched_group *group, struct task_struct *p, int this_cpu)
7377 {
7378 	unsigned long load, min_load = ULONG_MAX;
7379 	unsigned int min_exit_latency = UINT_MAX;
7380 	u64 latest_idle_timestamp = 0;
7381 	int least_loaded_cpu = this_cpu;
7382 	int shallowest_idle_cpu = -1;
7383 	int i;
7384 
7385 	/* Check if we have any choice: */
7386 	if (group->group_weight == 1)
7387 		return cpumask_first(sched_group_span(group));
7388 
7389 	/* Traverse only the allowed CPUs */
7390 	for_each_cpu_and(i, sched_group_span(group), p->cpus_ptr) {
7391 		struct rq *rq = cpu_rq(i);
7392 
7393 		if (!sched_core_cookie_match(rq, p))
7394 			continue;
7395 
7396 		if (sched_idle_cpu(i))
7397 			return i;
7398 
7399 		if (available_idle_cpu(i)) {
7400 			struct cpuidle_state *idle = idle_get_state(rq);
7401 			if (idle && idle->exit_latency < min_exit_latency) {
7402 				/*
7403 				 * We give priority to a CPU whose idle state
7404 				 * has the smallest exit latency irrespective
7405 				 * of any idle timestamp.
7406 				 */
7407 				min_exit_latency = idle->exit_latency;
7408 				latest_idle_timestamp = rq->idle_stamp;
7409 				shallowest_idle_cpu = i;
7410 			} else if ((!idle || idle->exit_latency == min_exit_latency) &&
7411 				   rq->idle_stamp > latest_idle_timestamp) {
7412 				/*
7413 				 * If equal or no active idle state, then
7414 				 * the most recently idled CPU might have
7415 				 * a warmer cache.
7416 				 */
7417 				latest_idle_timestamp = rq->idle_stamp;
7418 				shallowest_idle_cpu = i;
7419 			}
7420 		} else if (shallowest_idle_cpu == -1) {
7421 			load = cpu_load(cpu_rq(i));
7422 			if (load < min_load) {
7423 				min_load = load;
7424 				least_loaded_cpu = i;
7425 			}
7426 		}
7427 	}
7428 
7429 	return shallowest_idle_cpu != -1 ? shallowest_idle_cpu : least_loaded_cpu;
7430 }
7431 
7432 static inline int sched_balance_find_dst_cpu(struct sched_domain *sd, struct task_struct *p,
7433 				  int cpu, int prev_cpu, int sd_flag)
7434 {
7435 	int new_cpu = cpu;
7436 
7437 	if (!cpumask_intersects(sched_domain_span(sd), p->cpus_ptr))
7438 		return prev_cpu;
7439 
7440 	/*
7441 	 * We need task's util for cpu_util_without, sync it up to
7442 	 * prev_cpu's last_update_time.
7443 	 */
7444 	if (!(sd_flag & SD_BALANCE_FORK))
7445 		sync_entity_load_avg(&p->se);
7446 
7447 	while (sd) {
7448 		struct sched_group *group;
7449 		struct sched_domain *tmp;
7450 		int weight;
7451 
7452 		if (!(sd->flags & sd_flag)) {
7453 			sd = sd->child;
7454 			continue;
7455 		}
7456 
7457 		group = sched_balance_find_dst_group(sd, p, cpu);
7458 		if (!group) {
7459 			sd = sd->child;
7460 			continue;
7461 		}
7462 
7463 		new_cpu = sched_balance_find_dst_group_cpu(group, p, cpu);
7464 		if (new_cpu == cpu) {
7465 			/* Now try balancing at a lower domain level of 'cpu': */
7466 			sd = sd->child;
7467 			continue;
7468 		}
7469 
7470 		/* Now try balancing at a lower domain level of 'new_cpu': */
7471 		cpu = new_cpu;
7472 		weight = sd->span_weight;
7473 		sd = NULL;
7474 		for_each_domain(cpu, tmp) {
7475 			if (weight <= tmp->span_weight)
7476 				break;
7477 			if (tmp->flags & sd_flag)
7478 				sd = tmp;
7479 		}
7480 	}
7481 
7482 	return new_cpu;
7483 }
7484 
7485 static inline int __select_idle_cpu(int cpu, struct task_struct *p)
7486 {
7487 	if ((available_idle_cpu(cpu) || sched_idle_cpu(cpu)) &&
7488 	    sched_cpu_cookie_match(cpu_rq(cpu), p))
7489 		return cpu;
7490 
7491 	return -1;
7492 }
7493 
7494 #ifdef CONFIG_SCHED_SMT
7495 DEFINE_STATIC_KEY_FALSE(sched_smt_present);
7496 EXPORT_SYMBOL_GPL(sched_smt_present);
7497 
7498 static inline void set_idle_cores(int cpu, int val)
7499 {
7500 	struct sched_domain_shared *sds;
7501 
7502 	sds = rcu_dereference_all(per_cpu(sd_llc_shared, cpu));
7503 	if (sds)
7504 		WRITE_ONCE(sds->has_idle_cores, val);
7505 }
7506 
7507 static inline bool test_idle_cores(int cpu)
7508 {
7509 	struct sched_domain_shared *sds;
7510 
7511 	sds = rcu_dereference_all(per_cpu(sd_llc_shared, cpu));
7512 	if (sds)
7513 		return READ_ONCE(sds->has_idle_cores);
7514 
7515 	return false;
7516 }
7517 
7518 /*
7519  * Scans the local SMT mask to see if the entire core is idle, and records this
7520  * information in sd_llc_shared->has_idle_cores.
7521  *
7522  * Since SMT siblings share all cache levels, inspecting this limited remote
7523  * state should be fairly cheap.
7524  */
7525 void __update_idle_core(struct rq *rq)
7526 {
7527 	int core = cpu_of(rq);
7528 	int cpu;
7529 
7530 	rcu_read_lock();
7531 	if (test_idle_cores(core))
7532 		goto unlock;
7533 
7534 	for_each_cpu(cpu, cpu_smt_mask(core)) {
7535 		if (cpu == core)
7536 			continue;
7537 
7538 		if (!available_idle_cpu(cpu))
7539 			goto unlock;
7540 	}
7541 
7542 	set_idle_cores(core, 1);
7543 unlock:
7544 	rcu_read_unlock();
7545 }
7546 
7547 /*
7548  * Scan the entire LLC domain for idle cores; this dynamically switches off if
7549  * there are no idle cores left in the system; tracked through
7550  * sd_llc->shared->has_idle_cores and enabled through update_idle_core() above.
7551  */
7552 static int select_idle_core(struct task_struct *p, int core, struct cpumask *cpus, int *idle_cpu)
7553 {
7554 	bool idle = true;
7555 	int cpu;
7556 
7557 	for_each_cpu(cpu, cpu_smt_mask(core)) {
7558 		if (!available_idle_cpu(cpu)) {
7559 			idle = false;
7560 			if (*idle_cpu == -1) {
7561 				if (sched_idle_cpu(cpu) && cpumask_test_cpu(cpu, cpus)) {
7562 					*idle_cpu = cpu;
7563 					break;
7564 				}
7565 				continue;
7566 			}
7567 			break;
7568 		}
7569 		if (*idle_cpu == -1 && cpumask_test_cpu(cpu, cpus))
7570 			*idle_cpu = cpu;
7571 	}
7572 
7573 	if (idle)
7574 		return core;
7575 
7576 	cpumask_andnot(cpus, cpus, cpu_smt_mask(core));
7577 	return -1;
7578 }
7579 
7580 /*
7581  * Scan the local SMT mask for idle CPUs.
7582  */
7583 static int select_idle_smt(struct task_struct *p, struct sched_domain *sd, int target)
7584 {
7585 	int cpu;
7586 
7587 	for_each_cpu_and(cpu, cpu_smt_mask(target), p->cpus_ptr) {
7588 		if (cpu == target)
7589 			continue;
7590 		/*
7591 		 * Check if the CPU is in the LLC scheduling domain of @target.
7592 		 * Due to isolcpus, there is no guarantee that all the siblings are in the domain.
7593 		 */
7594 		if (!cpumask_test_cpu(cpu, sched_domain_span(sd)))
7595 			continue;
7596 		if (available_idle_cpu(cpu) || sched_idle_cpu(cpu))
7597 			return cpu;
7598 	}
7599 
7600 	return -1;
7601 }
7602 
7603 #else /* !CONFIG_SCHED_SMT: */
7604 
7605 static inline void set_idle_cores(int cpu, int val)
7606 {
7607 }
7608 
7609 static inline bool test_idle_cores(int cpu)
7610 {
7611 	return false;
7612 }
7613 
7614 static inline int select_idle_core(struct task_struct *p, int core, struct cpumask *cpus, int *idle_cpu)
7615 {
7616 	return __select_idle_cpu(core, p);
7617 }
7618 
7619 static inline int select_idle_smt(struct task_struct *p, struct sched_domain *sd, int target)
7620 {
7621 	return -1;
7622 }
7623 
7624 #endif /* !CONFIG_SCHED_SMT */
7625 
7626 /*
7627  * Scan the LLC domain for idle CPUs; this is dynamically regulated by
7628  * comparing the average scan cost (tracked in sd->avg_scan_cost) against the
7629  * average idle time for this rq (as found in rq->avg_idle).
7630  */
7631 static int select_idle_cpu(struct task_struct *p, struct sched_domain *sd, bool has_idle_core, int target)
7632 {
7633 	struct cpumask *cpus = this_cpu_cpumask_var_ptr(select_rq_mask);
7634 	int i, cpu, idle_cpu = -1, nr = INT_MAX;
7635 	struct sched_domain_shared *sd_share;
7636 
7637 	cpumask_and(cpus, sched_domain_span(sd), p->cpus_ptr);
7638 
7639 	if (sched_feat(SIS_UTIL)) {
7640 		sd_share = rcu_dereference_all(per_cpu(sd_llc_shared, target));
7641 		if (sd_share) {
7642 			/* because !--nr is the condition to stop scan */
7643 			nr = READ_ONCE(sd_share->nr_idle_scan) + 1;
7644 			/* overloaded LLC is unlikely to have idle cpu/core */
7645 			if (nr == 1)
7646 				return -1;
7647 		}
7648 	}
7649 
7650 	if (static_branch_unlikely(&sched_cluster_active)) {
7651 		struct sched_group *sg = sd->groups;
7652 
7653 		if (sg->flags & SD_CLUSTER) {
7654 			for_each_cpu_wrap(cpu, sched_group_span(sg), target + 1) {
7655 				if (!cpumask_test_cpu(cpu, cpus))
7656 					continue;
7657 
7658 				if (has_idle_core) {
7659 					i = select_idle_core(p, cpu, cpus, &idle_cpu);
7660 					if ((unsigned int)i < nr_cpumask_bits)
7661 						return i;
7662 				} else {
7663 					if (--nr <= 0)
7664 						return -1;
7665 					idle_cpu = __select_idle_cpu(cpu, p);
7666 					if ((unsigned int)idle_cpu < nr_cpumask_bits)
7667 						return idle_cpu;
7668 				}
7669 			}
7670 			cpumask_andnot(cpus, cpus, sched_group_span(sg));
7671 		}
7672 	}
7673 
7674 	for_each_cpu_wrap(cpu, cpus, target + 1) {
7675 		if (has_idle_core) {
7676 			i = select_idle_core(p, cpu, cpus, &idle_cpu);
7677 			if ((unsigned int)i < nr_cpumask_bits)
7678 				return i;
7679 
7680 		} else {
7681 			if (--nr <= 0)
7682 				return -1;
7683 			idle_cpu = __select_idle_cpu(cpu, p);
7684 			if ((unsigned int)idle_cpu < nr_cpumask_bits)
7685 				break;
7686 		}
7687 	}
7688 
7689 	if (has_idle_core)
7690 		set_idle_cores(target, false);
7691 
7692 	return idle_cpu;
7693 }
7694 
7695 /*
7696  * Scan the asym_capacity domain for idle CPUs; pick the first idle one on which
7697  * the task fits. If no CPU is big enough, but there are idle ones, try to
7698  * maximize capacity.
7699  */
7700 static int
7701 select_idle_capacity(struct task_struct *p, struct sched_domain *sd, int target)
7702 {
7703 	unsigned long task_util, util_min, util_max, best_cap = 0;
7704 	int fits, best_fits = 0;
7705 	int cpu, best_cpu = -1;
7706 	struct cpumask *cpus;
7707 
7708 	cpus = this_cpu_cpumask_var_ptr(select_rq_mask);
7709 	cpumask_and(cpus, sched_domain_span(sd), p->cpus_ptr);
7710 
7711 	task_util = task_util_est(p);
7712 	util_min = uclamp_eff_value(p, UCLAMP_MIN);
7713 	util_max = uclamp_eff_value(p, UCLAMP_MAX);
7714 
7715 	for_each_cpu_wrap(cpu, cpus, target) {
7716 		unsigned long cpu_cap = capacity_of(cpu);
7717 
7718 		if (!available_idle_cpu(cpu) && !sched_idle_cpu(cpu))
7719 			continue;
7720 
7721 		fits = util_fits_cpu(task_util, util_min, util_max, cpu);
7722 
7723 		/* This CPU fits with all requirements */
7724 		if (fits > 0)
7725 			return cpu;
7726 		/*
7727 		 * Only the min performance hint (i.e. uclamp_min) doesn't fit.
7728 		 * Look for the CPU with best capacity.
7729 		 */
7730 		else if (fits < 0)
7731 			cpu_cap = get_actual_cpu_capacity(cpu);
7732 
7733 		/*
7734 		 * First, select CPU which fits better (-1 being better than 0).
7735 		 * Then, select the one with best capacity at same level.
7736 		 */
7737 		if ((fits < best_fits) ||
7738 		    ((fits == best_fits) && (cpu_cap > best_cap))) {
7739 			best_cap = cpu_cap;
7740 			best_cpu = cpu;
7741 			best_fits = fits;
7742 		}
7743 	}
7744 
7745 	return best_cpu;
7746 }
7747 
7748 static inline bool asym_fits_cpu(unsigned long util,
7749 				 unsigned long util_min,
7750 				 unsigned long util_max,
7751 				 int cpu)
7752 {
7753 	if (sched_asym_cpucap_active())
7754 		/*
7755 		 * Return true only if the cpu fully fits the task requirements
7756 		 * which include the utilization and the performance hints.
7757 		 */
7758 		return (util_fits_cpu(util, util_min, util_max, cpu) > 0);
7759 
7760 	return true;
7761 }
7762 
7763 /*
7764  * Try and locate an idle core/thread in the LLC cache domain.
7765  */
7766 static int select_idle_sibling(struct task_struct *p, int prev, int target)
7767 {
7768 	bool has_idle_core = false;
7769 	struct sched_domain *sd;
7770 	unsigned long task_util, util_min, util_max;
7771 	int i, recent_used_cpu, prev_aff = -1;
7772 
7773 	/*
7774 	 * On asymmetric system, update task utilization because we will check
7775 	 * that the task fits with CPU's capacity.
7776 	 */
7777 	if (sched_asym_cpucap_active()) {
7778 		sync_entity_load_avg(&p->se);
7779 		task_util = task_util_est(p);
7780 		util_min = uclamp_eff_value(p, UCLAMP_MIN);
7781 		util_max = uclamp_eff_value(p, UCLAMP_MAX);
7782 	}
7783 
7784 	/*
7785 	 * per-cpu select_rq_mask usage
7786 	 */
7787 	lockdep_assert_irqs_disabled();
7788 
7789 	if ((available_idle_cpu(target) || sched_idle_cpu(target)) &&
7790 	    asym_fits_cpu(task_util, util_min, util_max, target))
7791 		return target;
7792 
7793 	/*
7794 	 * If the previous CPU is cache affine and idle, don't be stupid:
7795 	 */
7796 	if (prev != target && cpus_share_cache(prev, target) &&
7797 	    (available_idle_cpu(prev) || sched_idle_cpu(prev)) &&
7798 	    asym_fits_cpu(task_util, util_min, util_max, prev)) {
7799 
7800 		if (!static_branch_unlikely(&sched_cluster_active) ||
7801 		    cpus_share_resources(prev, target))
7802 			return prev;
7803 
7804 		prev_aff = prev;
7805 	}
7806 
7807 	/*
7808 	 * Allow a per-cpu kthread to stack with the wakee if the
7809 	 * kworker thread and the tasks previous CPUs are the same.
7810 	 * The assumption is that the wakee queued work for the
7811 	 * per-cpu kthread that is now complete and the wakeup is
7812 	 * essentially a sync wakeup. An obvious example of this
7813 	 * pattern is IO completions.
7814 	 */
7815 	if (is_per_cpu_kthread(current) &&
7816 	    in_task() &&
7817 	    prev == smp_processor_id() &&
7818 	    this_rq()->nr_running <= 1 &&
7819 	    asym_fits_cpu(task_util, util_min, util_max, prev)) {
7820 		return prev;
7821 	}
7822 
7823 	/* Check a recently used CPU as a potential idle candidate: */
7824 	recent_used_cpu = p->recent_used_cpu;
7825 	p->recent_used_cpu = prev;
7826 	if (recent_used_cpu != prev &&
7827 	    recent_used_cpu != target &&
7828 	    cpus_share_cache(recent_used_cpu, target) &&
7829 	    (available_idle_cpu(recent_used_cpu) || sched_idle_cpu(recent_used_cpu)) &&
7830 	    cpumask_test_cpu(recent_used_cpu, p->cpus_ptr) &&
7831 	    asym_fits_cpu(task_util, util_min, util_max, recent_used_cpu)) {
7832 
7833 		if (!static_branch_unlikely(&sched_cluster_active) ||
7834 		    cpus_share_resources(recent_used_cpu, target))
7835 			return recent_used_cpu;
7836 
7837 	} else {
7838 		recent_used_cpu = -1;
7839 	}
7840 
7841 	/*
7842 	 * For asymmetric CPU capacity systems, our domain of interest is
7843 	 * sd_asym_cpucapacity rather than sd_llc.
7844 	 */
7845 	if (sched_asym_cpucap_active()) {
7846 		sd = rcu_dereference_all(per_cpu(sd_asym_cpucapacity, target));
7847 		/*
7848 		 * On an asymmetric CPU capacity system where an exclusive
7849 		 * cpuset defines a symmetric island (i.e. one unique
7850 		 * capacity_orig value through the cpuset), the key will be set
7851 		 * but the CPUs within that cpuset will not have a domain with
7852 		 * SD_ASYM_CPUCAPACITY. These should follow the usual symmetric
7853 		 * capacity path.
7854 		 */
7855 		if (sd) {
7856 			i = select_idle_capacity(p, sd, target);
7857 			return ((unsigned)i < nr_cpumask_bits) ? i : target;
7858 		}
7859 	}
7860 
7861 	sd = rcu_dereference_all(per_cpu(sd_llc, target));
7862 	if (!sd)
7863 		return target;
7864 
7865 	if (sched_smt_active()) {
7866 		has_idle_core = test_idle_cores(target);
7867 
7868 		if (!has_idle_core && cpus_share_cache(prev, target)) {
7869 			i = select_idle_smt(p, sd, prev);
7870 			if ((unsigned int)i < nr_cpumask_bits)
7871 				return i;
7872 		}
7873 	}
7874 
7875 	i = select_idle_cpu(p, sd, has_idle_core, target);
7876 	if ((unsigned)i < nr_cpumask_bits)
7877 		return i;
7878 
7879 	/*
7880 	 * For cluster machines which have lower sharing cache like L2 or
7881 	 * LLC Tag, we tend to find an idle CPU in the target's cluster
7882 	 * first. But prev_cpu or recent_used_cpu may also be a good candidate,
7883 	 * use them if possible when no idle CPU found in select_idle_cpu().
7884 	 */
7885 	if ((unsigned int)prev_aff < nr_cpumask_bits)
7886 		return prev_aff;
7887 	if ((unsigned int)recent_used_cpu < nr_cpumask_bits)
7888 		return recent_used_cpu;
7889 
7890 	return target;
7891 }
7892 
7893 /**
7894  * cpu_util() - Estimates the amount of CPU capacity used by CFS tasks.
7895  * @cpu: the CPU to get the utilization for
7896  * @p: task for which the CPU utilization should be predicted or NULL
7897  * @dst_cpu: CPU @p migrates to, -1 if @p moves from @cpu or @p == NULL
7898  * @boost: 1 to enable boosting, otherwise 0
7899  *
7900  * The unit of the return value must be the same as the one of CPU capacity
7901  * so that CPU utilization can be compared with CPU capacity.
7902  *
7903  * CPU utilization is the sum of running time of runnable tasks plus the
7904  * recent utilization of currently non-runnable tasks on that CPU.
7905  * It represents the amount of CPU capacity currently used by CFS tasks in
7906  * the range [0..max CPU capacity] with max CPU capacity being the CPU
7907  * capacity at f_max.
7908  *
7909  * The estimated CPU utilization is defined as the maximum between CPU
7910  * utilization and sum of the estimated utilization of the currently
7911  * runnable tasks on that CPU. It preserves a utilization "snapshot" of
7912  * previously-executed tasks, which helps better deduce how busy a CPU will
7913  * be when a long-sleeping task wakes up. The contribution to CPU utilization
7914  * of such a task would be significantly decayed at this point of time.
7915  *
7916  * Boosted CPU utilization is defined as max(CPU runnable, CPU utilization).
7917  * CPU contention for CFS tasks can be detected by CPU runnable > CPU
7918  * utilization. Boosting is implemented in cpu_util() so that internal
7919  * users (e.g. EAS) can use it next to external users (e.g. schedutil),
7920  * latter via cpu_util_cfs_boost().
7921  *
7922  * CPU utilization can be higher than the current CPU capacity
7923  * (f_curr/f_max * max CPU capacity) or even the max CPU capacity because
7924  * of rounding errors as well as task migrations or wakeups of new tasks.
7925  * CPU utilization has to be capped to fit into the [0..max CPU capacity]
7926  * range. Otherwise a group of CPUs (CPU0 util = 121% + CPU1 util = 80%)
7927  * could be seen as over-utilized even though CPU1 has 20% of spare CPU
7928  * capacity. CPU utilization is allowed to overshoot current CPU capacity
7929  * though since this is useful for predicting the CPU capacity required
7930  * after task migrations (scheduler-driven DVFS).
7931  *
7932  * Return: (Boosted) (estimated) utilization for the specified CPU.
7933  */
7934 static unsigned long
7935 cpu_util(int cpu, struct task_struct *p, int dst_cpu, int boost)
7936 {
7937 	struct cfs_rq *cfs_rq = &cpu_rq(cpu)->cfs;
7938 	unsigned long util = READ_ONCE(cfs_rq->avg.util_avg);
7939 	unsigned long runnable;
7940 
7941 	if (boost) {
7942 		runnable = READ_ONCE(cfs_rq->avg.runnable_avg);
7943 		util = max(util, runnable);
7944 	}
7945 
7946 	/*
7947 	 * If @dst_cpu is -1 or @p migrates from @cpu to @dst_cpu remove its
7948 	 * contribution. If @p migrates from another CPU to @cpu add its
7949 	 * contribution. In all the other cases @cpu is not impacted by the
7950 	 * migration so its util_avg is already correct.
7951 	 */
7952 	if (p && task_cpu(p) == cpu && dst_cpu != cpu)
7953 		lsub_positive(&util, task_util(p));
7954 	else if (p && task_cpu(p) != cpu && dst_cpu == cpu)
7955 		util += task_util(p);
7956 
7957 	if (sched_feat(UTIL_EST)) {
7958 		unsigned long util_est;
7959 
7960 		util_est = READ_ONCE(cfs_rq->avg.util_est);
7961 
7962 		/*
7963 		 * During wake-up @p isn't enqueued yet and doesn't contribute
7964 		 * to any cpu_rq(cpu)->cfs.avg.util_est.
7965 		 * If @dst_cpu == @cpu add it to "simulate" cpu_util after @p
7966 		 * has been enqueued.
7967 		 *
7968 		 * During exec (@dst_cpu = -1) @p is enqueued and does
7969 		 * contribute to cpu_rq(cpu)->cfs.util_est.
7970 		 * Remove it to "simulate" cpu_util without @p's contribution.
7971 		 *
7972 		 * Despite the task_on_rq_queued(@p) check there is still a
7973 		 * small window for a possible race when an exec
7974 		 * select_task_rq_fair() races with LB's detach_task().
7975 		 *
7976 		 *   detach_task()
7977 		 *     deactivate_task()
7978 		 *       p->on_rq = TASK_ON_RQ_MIGRATING;
7979 		 *       -------------------------------- A
7980 		 *       dequeue_task()                    \
7981 		 *         dequeue_task_fair()              + Race Time
7982 		 *           util_est_dequeue()            /
7983 		 *       -------------------------------- B
7984 		 *
7985 		 * The additional check "current == p" is required to further
7986 		 * reduce the race window.
7987 		 */
7988 		if (dst_cpu == cpu)
7989 			util_est += _task_util_est(p);
7990 		else if (p && unlikely(task_on_rq_queued(p) || current == p))
7991 			lsub_positive(&util_est, _task_util_est(p));
7992 
7993 		util = max(util, util_est);
7994 	}
7995 
7996 	return min(util, arch_scale_cpu_capacity(cpu));
7997 }
7998 
7999 unsigned long cpu_util_cfs(int cpu)
8000 {
8001 	return cpu_util(cpu, NULL, -1, 0);
8002 }
8003 
8004 unsigned long cpu_util_cfs_boost(int cpu)
8005 {
8006 	return cpu_util(cpu, NULL, -1, 1);
8007 }
8008 
8009 /*
8010  * cpu_util_without: compute cpu utilization without any contributions from *p
8011  * @cpu: the CPU which utilization is requested
8012  * @p: the task which utilization should be discounted
8013  *
8014  * The utilization of a CPU is defined by the utilization of tasks currently
8015  * enqueued on that CPU as well as tasks which are currently sleeping after an
8016  * execution on that CPU.
8017  *
8018  * This method returns the utilization of the specified CPU by discounting the
8019  * utilization of the specified task, whenever the task is currently
8020  * contributing to the CPU utilization.
8021  */
8022 static unsigned long cpu_util_without(int cpu, struct task_struct *p)
8023 {
8024 	/* Task has no contribution or is new */
8025 	if (cpu != task_cpu(p) || !READ_ONCE(p->se.avg.last_update_time))
8026 		p = NULL;
8027 
8028 	return cpu_util(cpu, p, -1, 0);
8029 }
8030 
8031 /*
8032  * This function computes an effective utilization for the given CPU, to be
8033  * used for frequency selection given the linear relation: f = u * f_max.
8034  *
8035  * The scheduler tracks the following metrics:
8036  *
8037  *   cpu_util_{cfs,rt,dl,irq}()
8038  *   cpu_bw_dl()
8039  *
8040  * Where the cfs,rt and dl util numbers are tracked with the same metric and
8041  * synchronized windows and are thus directly comparable.
8042  *
8043  * The cfs,rt,dl utilization are the running times measured with rq->clock_task
8044  * which excludes things like IRQ and steal-time. These latter are then accrued
8045  * in the IRQ utilization.
8046  *
8047  * The DL bandwidth number OTOH is not a measured metric but a value computed
8048  * based on the task model parameters and gives the minimal utilization
8049  * required to meet deadlines.
8050  */
8051 unsigned long effective_cpu_util(int cpu, unsigned long util_cfs,
8052 				 unsigned long *min,
8053 				 unsigned long *max)
8054 {
8055 	unsigned long util, irq, scale;
8056 	struct rq *rq = cpu_rq(cpu);
8057 
8058 	scale = arch_scale_cpu_capacity(cpu);
8059 
8060 	/*
8061 	 * Early check to see if IRQ/steal time saturates the CPU, can be
8062 	 * because of inaccuracies in how we track these -- see
8063 	 * update_irq_load_avg().
8064 	 */
8065 	irq = cpu_util_irq(rq);
8066 	if (unlikely(irq >= scale)) {
8067 		if (min)
8068 			*min = scale;
8069 		if (max)
8070 			*max = scale;
8071 		return scale;
8072 	}
8073 
8074 	if (min) {
8075 		/*
8076 		 * The minimum utilization returns the highest level between:
8077 		 * - the computed DL bandwidth needed with the IRQ pressure which
8078 		 *   steals time to the deadline task.
8079 		 * - The minimum performance requirement for CFS and/or RT.
8080 		 */
8081 		*min = max(irq + cpu_bw_dl(rq), uclamp_rq_get(rq, UCLAMP_MIN));
8082 
8083 		/*
8084 		 * When an RT task is runnable and uclamp is not used, we must
8085 		 * ensure that the task will run at maximum compute capacity.
8086 		 */
8087 		if (!uclamp_is_used() && rt_rq_is_runnable(&rq->rt))
8088 			*min = max(*min, scale);
8089 	}
8090 
8091 	/*
8092 	 * Because the time spend on RT/DL tasks is visible as 'lost' time to
8093 	 * CFS tasks and we use the same metric to track the effective
8094 	 * utilization (PELT windows are synchronized) we can directly add them
8095 	 * to obtain the CPU's actual utilization.
8096 	 */
8097 	util = util_cfs + cpu_util_rt(rq);
8098 	util += cpu_util_dl(rq);
8099 
8100 	/*
8101 	 * The maximum hint is a soft bandwidth requirement, which can be lower
8102 	 * than the actual utilization because of uclamp_max requirements.
8103 	 */
8104 	if (max)
8105 		*max = min(scale, uclamp_rq_get(rq, UCLAMP_MAX));
8106 
8107 	if (util >= scale)
8108 		return scale;
8109 
8110 	/*
8111 	 * There is still idle time; further improve the number by using the
8112 	 * IRQ metric. Because IRQ/steal time is hidden from the task clock we
8113 	 * need to scale the task numbers:
8114 	 *
8115 	 *              max - irq
8116 	 *   U' = irq + --------- * U
8117 	 *                 max
8118 	 */
8119 	util = scale_irq_capacity(util, irq, scale);
8120 	util += irq;
8121 
8122 	return min(scale, util);
8123 }
8124 
8125 unsigned long sched_cpu_util(int cpu)
8126 {
8127 	return effective_cpu_util(cpu, cpu_util_cfs(cpu), NULL, NULL);
8128 }
8129 
8130 /*
8131  * energy_env - Utilization landscape for energy estimation.
8132  * @task_busy_time: Utilization contribution by the task for which we test the
8133  *                  placement. Given by eenv_task_busy_time().
8134  * @pd_busy_time:   Utilization of the whole perf domain without the task
8135  *                  contribution. Given by eenv_pd_busy_time().
8136  * @cpu_cap:        Maximum CPU capacity for the perf domain.
8137  * @pd_cap:         Entire perf domain capacity. (pd->nr_cpus * cpu_cap).
8138  */
8139 struct energy_env {
8140 	unsigned long task_busy_time;
8141 	unsigned long pd_busy_time;
8142 	unsigned long cpu_cap;
8143 	unsigned long pd_cap;
8144 };
8145 
8146 /*
8147  * Compute the task busy time for compute_energy(). This time cannot be
8148  * injected directly into effective_cpu_util() because of the IRQ scaling.
8149  * The latter only makes sense with the most recent CPUs where the task has
8150  * run.
8151  */
8152 static inline void eenv_task_busy_time(struct energy_env *eenv,
8153 				       struct task_struct *p, int prev_cpu)
8154 {
8155 	unsigned long busy_time, max_cap = arch_scale_cpu_capacity(prev_cpu);
8156 	unsigned long irq = cpu_util_irq(cpu_rq(prev_cpu));
8157 
8158 	if (unlikely(irq >= max_cap))
8159 		busy_time = max_cap;
8160 	else
8161 		busy_time = scale_irq_capacity(task_util_est(p), irq, max_cap);
8162 
8163 	eenv->task_busy_time = busy_time;
8164 }
8165 
8166 /*
8167  * Compute the perf_domain (PD) busy time for compute_energy(). Based on the
8168  * utilization for each @pd_cpus, it however doesn't take into account
8169  * clamping since the ratio (utilization / cpu_capacity) is already enough to
8170  * scale the EM reported power consumption at the (eventually clamped)
8171  * cpu_capacity.
8172  *
8173  * The contribution of the task @p for which we want to estimate the
8174  * energy cost is removed (by cpu_util()) and must be calculated
8175  * separately (see eenv_task_busy_time). This ensures:
8176  *
8177  *   - A stable PD utilization, no matter which CPU of that PD we want to place
8178  *     the task on.
8179  *
8180  *   - A fair comparison between CPUs as the task contribution (task_util())
8181  *     will always be the same no matter which CPU utilization we rely on
8182  *     (util_avg or util_est).
8183  *
8184  * Set @eenv busy time for the PD that spans @pd_cpus. This busy time can't
8185  * exceed @eenv->pd_cap.
8186  */
8187 static inline void eenv_pd_busy_time(struct energy_env *eenv,
8188 				     struct cpumask *pd_cpus,
8189 				     struct task_struct *p)
8190 {
8191 	unsigned long busy_time = 0;
8192 	int cpu;
8193 
8194 	for_each_cpu(cpu, pd_cpus) {
8195 		unsigned long util = cpu_util(cpu, p, -1, 0);
8196 
8197 		busy_time += effective_cpu_util(cpu, util, NULL, NULL);
8198 	}
8199 
8200 	eenv->pd_busy_time = min(eenv->pd_cap, busy_time);
8201 }
8202 
8203 /*
8204  * Compute the maximum utilization for compute_energy() when the task @p
8205  * is placed on the cpu @dst_cpu.
8206  *
8207  * Returns the maximum utilization among @eenv->cpus. This utilization can't
8208  * exceed @eenv->cpu_cap.
8209  */
8210 static inline unsigned long
8211 eenv_pd_max_util(struct energy_env *eenv, struct cpumask *pd_cpus,
8212 		 struct task_struct *p, int dst_cpu)
8213 {
8214 	unsigned long max_util = 0;
8215 	int cpu;
8216 
8217 	for_each_cpu(cpu, pd_cpus) {
8218 		struct task_struct *tsk = (cpu == dst_cpu) ? p : NULL;
8219 		unsigned long util = cpu_util(cpu, p, dst_cpu, 1);
8220 		unsigned long eff_util, min, max;
8221 
8222 		/*
8223 		 * Performance domain frequency: utilization clamping
8224 		 * must be considered since it affects the selection
8225 		 * of the performance domain frequency.
8226 		 * NOTE: in case RT tasks are running, by default the min
8227 		 * utilization can be max OPP.
8228 		 */
8229 		eff_util = effective_cpu_util(cpu, util, &min, &max);
8230 
8231 		/* Task's uclamp can modify min and max value */
8232 		if (tsk && uclamp_is_used()) {
8233 			min = max(min, uclamp_eff_value(p, UCLAMP_MIN));
8234 
8235 			/*
8236 			 * If there is no active max uclamp constraint,
8237 			 * directly use task's one, otherwise keep max.
8238 			 */
8239 			if (uclamp_rq_is_idle(cpu_rq(cpu)))
8240 				max = uclamp_eff_value(p, UCLAMP_MAX);
8241 			else
8242 				max = max(max, uclamp_eff_value(p, UCLAMP_MAX));
8243 		}
8244 
8245 		eff_util = sugov_effective_cpu_perf(cpu, eff_util, min, max);
8246 		max_util = max(max_util, eff_util);
8247 	}
8248 
8249 	return min(max_util, eenv->cpu_cap);
8250 }
8251 
8252 /*
8253  * compute_energy(): Use the Energy Model to estimate the energy that @pd would
8254  * consume for a given utilization landscape @eenv. When @dst_cpu < 0, the task
8255  * contribution is ignored.
8256  */
8257 static inline unsigned long
8258 compute_energy(struct energy_env *eenv, struct perf_domain *pd,
8259 	       struct cpumask *pd_cpus, struct task_struct *p, int dst_cpu)
8260 {
8261 	unsigned long max_util = eenv_pd_max_util(eenv, pd_cpus, p, dst_cpu);
8262 	unsigned long busy_time = eenv->pd_busy_time;
8263 	unsigned long energy;
8264 
8265 	if (dst_cpu >= 0)
8266 		busy_time = min(eenv->pd_cap, busy_time + eenv->task_busy_time);
8267 
8268 	energy = em_cpu_energy(pd->em_pd, max_util, busy_time, eenv->cpu_cap);
8269 
8270 	trace_sched_compute_energy_tp(p, dst_cpu, energy, max_util, busy_time);
8271 
8272 	return energy;
8273 }
8274 
8275 /*
8276  * find_energy_efficient_cpu(): Find most energy-efficient target CPU for the
8277  * waking task. find_energy_efficient_cpu() looks for the CPU with maximum
8278  * spare capacity in each performance domain and uses it as a potential
8279  * candidate to execute the task. Then, it uses the Energy Model to figure
8280  * out which of the CPU candidates is the most energy-efficient.
8281  *
8282  * The rationale for this heuristic is as follows. In a performance domain,
8283  * all the most energy efficient CPU candidates (according to the Energy
8284  * Model) are those for which we'll request a low frequency. When there are
8285  * several CPUs for which the frequency request will be the same, we don't
8286  * have enough data to break the tie between them, because the Energy Model
8287  * only includes active power costs. With this model, if we assume that
8288  * frequency requests follow utilization (e.g. using schedutil), the CPU with
8289  * the maximum spare capacity in a performance domain is guaranteed to be among
8290  * the best candidates of the performance domain.
8291  *
8292  * In practice, it could be preferable from an energy standpoint to pack
8293  * small tasks on a CPU in order to let other CPUs go in deeper idle states,
8294  * but that could also hurt our chances to go cluster idle, and we have no
8295  * ways to tell with the current Energy Model if this is actually a good
8296  * idea or not. So, find_energy_efficient_cpu() basically favors
8297  * cluster-packing, and spreading inside a cluster. That should at least be
8298  * a good thing for latency, and this is consistent with the idea that most
8299  * of the energy savings of EAS come from the asymmetry of the system, and
8300  * not so much from breaking the tie between identical CPUs. That's also the
8301  * reason why EAS is enabled in the topology code only for systems where
8302  * SD_ASYM_CPUCAPACITY is set.
8303  *
8304  * NOTE: Forkees are not accepted in the energy-aware wake-up path because
8305  * they don't have any useful utilization data yet and it's not possible to
8306  * forecast their impact on energy consumption. Consequently, they will be
8307  * placed by sched_balance_find_dst_cpu() on the least loaded CPU, which might turn out
8308  * to be energy-inefficient in some use-cases. The alternative would be to
8309  * bias new tasks towards specific types of CPUs first, or to try to infer
8310  * their util_avg from the parent task, but those heuristics could hurt
8311  * other use-cases too. So, until someone finds a better way to solve this,
8312  * let's keep things simple by re-using the existing slow path.
8313  */
8314 static int find_energy_efficient_cpu(struct task_struct *p, int prev_cpu)
8315 {
8316 	struct cpumask *cpus = this_cpu_cpumask_var_ptr(select_rq_mask);
8317 	unsigned long prev_delta = ULONG_MAX, best_delta = ULONG_MAX;
8318 	unsigned long p_util_min = uclamp_is_used() ? uclamp_eff_value(p, UCLAMP_MIN) : 0;
8319 	unsigned long p_util_max = uclamp_is_used() ? uclamp_eff_value(p, UCLAMP_MAX) : 1024;
8320 	struct root_domain *rd = this_rq()->rd;
8321 	int cpu, best_energy_cpu, target = -1;
8322 	int prev_fits = -1, best_fits = -1;
8323 	unsigned long best_actual_cap = 0;
8324 	unsigned long prev_actual_cap = 0;
8325 	struct sched_domain *sd;
8326 	struct perf_domain *pd;
8327 	struct energy_env eenv;
8328 
8329 	rcu_read_lock();
8330 	pd = rcu_dereference_all(rd->pd);
8331 	if (!pd)
8332 		goto unlock;
8333 
8334 	/*
8335 	 * Energy-aware wake-up happens on the lowest sched_domain starting
8336 	 * from sd_asym_cpucapacity spanning over this_cpu and prev_cpu.
8337 	 */
8338 	sd = rcu_dereference_all(*this_cpu_ptr(&sd_asym_cpucapacity));
8339 	while (sd && !cpumask_test_cpu(prev_cpu, sched_domain_span(sd)))
8340 		sd = sd->parent;
8341 	if (!sd)
8342 		goto unlock;
8343 
8344 	target = prev_cpu;
8345 
8346 	sync_entity_load_avg(&p->se);
8347 	if (!task_util_est(p) && p_util_min == 0)
8348 		goto unlock;
8349 
8350 	eenv_task_busy_time(&eenv, p, prev_cpu);
8351 
8352 	for (; pd; pd = pd->next) {
8353 		unsigned long util_min = p_util_min, util_max = p_util_max;
8354 		unsigned long cpu_cap, cpu_actual_cap, util;
8355 		long prev_spare_cap = -1, max_spare_cap = -1;
8356 		unsigned long rq_util_min, rq_util_max;
8357 		unsigned long cur_delta, base_energy;
8358 		int max_spare_cap_cpu = -1;
8359 		int fits, max_fits = -1;
8360 
8361 		if (!cpumask_and(cpus, perf_domain_span(pd), cpu_online_mask))
8362 			continue;
8363 
8364 		/* Account external pressure for the energy estimation */
8365 		cpu = cpumask_first(cpus);
8366 		cpu_actual_cap = get_actual_cpu_capacity(cpu);
8367 
8368 		eenv.cpu_cap = cpu_actual_cap;
8369 		eenv.pd_cap = 0;
8370 
8371 		for_each_cpu(cpu, cpus) {
8372 			struct rq *rq = cpu_rq(cpu);
8373 
8374 			eenv.pd_cap += cpu_actual_cap;
8375 
8376 			if (!cpumask_test_cpu(cpu, sched_domain_span(sd)))
8377 				continue;
8378 
8379 			if (!cpumask_test_cpu(cpu, p->cpus_ptr))
8380 				continue;
8381 
8382 			util = cpu_util(cpu, p, cpu, 0);
8383 			cpu_cap = capacity_of(cpu);
8384 
8385 			/*
8386 			 * Skip CPUs that cannot satisfy the capacity request.
8387 			 * IOW, placing the task there would make the CPU
8388 			 * overutilized. Take uclamp into account to see how
8389 			 * much capacity we can get out of the CPU; this is
8390 			 * aligned with sched_cpu_util().
8391 			 */
8392 			if (uclamp_is_used() && !uclamp_rq_is_idle(rq)) {
8393 				/*
8394 				 * Open code uclamp_rq_util_with() except for
8395 				 * the clamp() part. I.e.: apply max aggregation
8396 				 * only. util_fits_cpu() logic requires to
8397 				 * operate on non clamped util but must use the
8398 				 * max-aggregated uclamp_{min, max}.
8399 				 */
8400 				rq_util_min = uclamp_rq_get(rq, UCLAMP_MIN);
8401 				rq_util_max = uclamp_rq_get(rq, UCLAMP_MAX);
8402 
8403 				util_min = max(rq_util_min, p_util_min);
8404 				util_max = max(rq_util_max, p_util_max);
8405 			}
8406 
8407 			fits = util_fits_cpu(util, util_min, util_max, cpu);
8408 			if (!fits)
8409 				continue;
8410 
8411 			lsub_positive(&cpu_cap, util);
8412 
8413 			if (cpu == prev_cpu) {
8414 				/* Always use prev_cpu as a candidate. */
8415 				prev_spare_cap = cpu_cap;
8416 				prev_fits = fits;
8417 			} else if ((fits > max_fits) ||
8418 				   ((fits == max_fits) && ((long)cpu_cap > max_spare_cap))) {
8419 				/*
8420 				 * Find the CPU with the maximum spare capacity
8421 				 * among the remaining CPUs in the performance
8422 				 * domain.
8423 				 */
8424 				max_spare_cap = cpu_cap;
8425 				max_spare_cap_cpu = cpu;
8426 				max_fits = fits;
8427 			}
8428 		}
8429 
8430 		if (max_spare_cap_cpu < 0 && prev_spare_cap < 0)
8431 			continue;
8432 
8433 		eenv_pd_busy_time(&eenv, cpus, p);
8434 		/* Compute the 'base' energy of the pd, without @p */
8435 		base_energy = compute_energy(&eenv, pd, cpus, p, -1);
8436 
8437 		/* Evaluate the energy impact of using prev_cpu. */
8438 		if (prev_spare_cap > -1) {
8439 			prev_delta = compute_energy(&eenv, pd, cpus, p,
8440 						    prev_cpu);
8441 			/* CPU utilization has changed */
8442 			if (prev_delta < base_energy)
8443 				goto unlock;
8444 			prev_delta -= base_energy;
8445 			prev_actual_cap = cpu_actual_cap;
8446 			best_delta = min(best_delta, prev_delta);
8447 		}
8448 
8449 		/* Evaluate the energy impact of using max_spare_cap_cpu. */
8450 		if (max_spare_cap_cpu >= 0 && max_spare_cap > prev_spare_cap) {
8451 			/* Current best energy cpu fits better */
8452 			if (max_fits < best_fits)
8453 				continue;
8454 
8455 			/*
8456 			 * Both don't fit performance hint (i.e. uclamp_min)
8457 			 * but best energy cpu has better capacity.
8458 			 */
8459 			if ((max_fits < 0) &&
8460 			    (cpu_actual_cap <= best_actual_cap))
8461 				continue;
8462 
8463 			cur_delta = compute_energy(&eenv, pd, cpus, p,
8464 						   max_spare_cap_cpu);
8465 			/* CPU utilization has changed */
8466 			if (cur_delta < base_energy)
8467 				goto unlock;
8468 			cur_delta -= base_energy;
8469 
8470 			/*
8471 			 * Both fit for the task but best energy cpu has lower
8472 			 * energy impact.
8473 			 */
8474 			if ((max_fits > 0) && (best_fits > 0) &&
8475 			    (cur_delta >= best_delta))
8476 				continue;
8477 
8478 			best_delta = cur_delta;
8479 			best_energy_cpu = max_spare_cap_cpu;
8480 			best_fits = max_fits;
8481 			best_actual_cap = cpu_actual_cap;
8482 		}
8483 	}
8484 	rcu_read_unlock();
8485 
8486 	if ((best_fits > prev_fits) ||
8487 	    ((best_fits > 0) && (best_delta < prev_delta)) ||
8488 	    ((best_fits < 0) && (best_actual_cap > prev_actual_cap)))
8489 		target = best_energy_cpu;
8490 
8491 	return target;
8492 
8493 unlock:
8494 	rcu_read_unlock();
8495 
8496 	return target;
8497 }
8498 
8499 /*
8500  * select_task_rq_fair: Select target runqueue for the waking task in domains
8501  * that have the relevant SD flag set. In practice, this is SD_BALANCE_WAKE,
8502  * SD_BALANCE_FORK, or SD_BALANCE_EXEC.
8503  *
8504  * Balances load by selecting the idlest CPU in the idlest group, or under
8505  * certain conditions an idle sibling CPU if the domain has SD_WAKE_AFFINE set.
8506  *
8507  * Returns the target CPU number.
8508  */
8509 static int
8510 select_task_rq_fair(struct task_struct *p, int prev_cpu, int wake_flags)
8511 {
8512 	int sync = (wake_flags & WF_SYNC) && !(current->flags & PF_EXITING);
8513 	struct sched_domain *tmp, *sd = NULL;
8514 	int cpu = smp_processor_id();
8515 	int new_cpu = prev_cpu;
8516 	int want_affine = 0;
8517 	/* SD_flags and WF_flags share the first nibble */
8518 	int sd_flag = wake_flags & 0xF;
8519 
8520 	/*
8521 	 * required for stable ->cpus_allowed
8522 	 */
8523 	lockdep_assert_held(&p->pi_lock);
8524 	if (wake_flags & WF_TTWU) {
8525 		record_wakee(p);
8526 
8527 		if ((wake_flags & WF_CURRENT_CPU) &&
8528 		    cpumask_test_cpu(cpu, p->cpus_ptr))
8529 			return cpu;
8530 
8531 		if (!is_rd_overutilized(this_rq()->rd)) {
8532 			new_cpu = find_energy_efficient_cpu(p, prev_cpu);
8533 			if (new_cpu >= 0)
8534 				return new_cpu;
8535 			new_cpu = prev_cpu;
8536 		}
8537 
8538 		want_affine = !wake_wide(p) && cpumask_test_cpu(cpu, p->cpus_ptr);
8539 	}
8540 
8541 	rcu_read_lock();
8542 	for_each_domain(cpu, tmp) {
8543 		/*
8544 		 * If both 'cpu' and 'prev_cpu' are part of this domain,
8545 		 * cpu is a valid SD_WAKE_AFFINE target.
8546 		 */
8547 		if (want_affine && (tmp->flags & SD_WAKE_AFFINE) &&
8548 		    cpumask_test_cpu(prev_cpu, sched_domain_span(tmp))) {
8549 			if (cpu != prev_cpu)
8550 				new_cpu = wake_affine(tmp, p, cpu, prev_cpu, sync);
8551 
8552 			sd = NULL; /* Prefer wake_affine over balance flags */
8553 			break;
8554 		}
8555 
8556 		/*
8557 		 * Usually only true for WF_EXEC and WF_FORK, as sched_domains
8558 		 * usually do not have SD_BALANCE_WAKE set. That means wakeup
8559 		 * will usually go to the fast path.
8560 		 */
8561 		if (tmp->flags & sd_flag)
8562 			sd = tmp;
8563 		else if (!want_affine)
8564 			break;
8565 	}
8566 
8567 	if (unlikely(sd)) {
8568 		/* Slow path */
8569 		new_cpu = sched_balance_find_dst_cpu(sd, p, cpu, prev_cpu, sd_flag);
8570 	} else if (wake_flags & WF_TTWU) { /* XXX always ? */
8571 		/* Fast path */
8572 		new_cpu = select_idle_sibling(p, prev_cpu, new_cpu);
8573 	}
8574 	rcu_read_unlock();
8575 
8576 	return new_cpu;
8577 }
8578 
8579 /*
8580  * Called immediately before a task is migrated to a new CPU; task_cpu(p) and
8581  * cfs_rq_of(p) references at time of call are still valid and identify the
8582  * previous CPU. The caller guarantees p->pi_lock or task_rq(p)->lock is held.
8583  */
8584 static void migrate_task_rq_fair(struct task_struct *p, int new_cpu)
8585 {
8586 	struct sched_entity *se = &p->se;
8587 
8588 	if (!task_on_rq_migrating(p)) {
8589 		remove_entity_load_avg(se);
8590 
8591 		/*
8592 		 * Here, the task's PELT values have been updated according to
8593 		 * the current rq's clock. But if that clock hasn't been
8594 		 * updated in a while, a substantial idle time will be missed,
8595 		 * leading to an inflation after wake-up on the new rq.
8596 		 *
8597 		 * Estimate the missing time from the cfs_rq last_update_time
8598 		 * and update sched_avg to improve the PELT continuity after
8599 		 * migration.
8600 		 */
8601 		migrate_se_pelt_lag(se);
8602 	}
8603 
8604 	/* Tell new CPU we are migrated */
8605 	se->avg.last_update_time = 0;
8606 
8607 	update_scan_period(p, new_cpu);
8608 }
8609 
8610 static void task_dead_fair(struct task_struct *p)
8611 {
8612 	struct sched_entity *se = &p->se;
8613 
8614 	if (se->sched_delayed) {
8615 		struct rq_flags rf;
8616 		struct rq *rq;
8617 
8618 		rq = task_rq_lock(p, &rf);
8619 		if (se->sched_delayed) {
8620 			update_rq_clock(rq);
8621 			dequeue_entities(rq, se, DEQUEUE_SLEEP | DEQUEUE_DELAYED);
8622 		}
8623 		task_rq_unlock(rq, p, &rf);
8624 	}
8625 
8626 	remove_entity_load_avg(se);
8627 }
8628 
8629 /*
8630  * Set the max capacity the task is allowed to run at for misfit detection.
8631  */
8632 static void set_task_max_allowed_capacity(struct task_struct *p)
8633 {
8634 	struct asym_cap_data *entry;
8635 
8636 	if (!sched_asym_cpucap_active())
8637 		return;
8638 
8639 	rcu_read_lock();
8640 	list_for_each_entry_rcu(entry, &asym_cap_list, link) {
8641 		cpumask_t *cpumask;
8642 
8643 		cpumask = cpu_capacity_span(entry);
8644 		if (!cpumask_intersects(p->cpus_ptr, cpumask))
8645 			continue;
8646 
8647 		p->max_allowed_capacity = entry->capacity;
8648 		break;
8649 	}
8650 	rcu_read_unlock();
8651 }
8652 
8653 static void set_cpus_allowed_fair(struct task_struct *p, struct affinity_context *ctx)
8654 {
8655 	set_cpus_allowed_common(p, ctx);
8656 	set_task_max_allowed_capacity(p);
8657 }
8658 
8659 static void set_next_buddy(struct sched_entity *se)
8660 {
8661 	for_each_sched_entity(se) {
8662 		if (WARN_ON_ONCE(!se->on_rq))
8663 			return;
8664 		if (se_is_idle(se))
8665 			return;
8666 		cfs_rq_of(se)->next = se;
8667 	}
8668 }
8669 
8670 enum preempt_wakeup_action {
8671 	PREEMPT_WAKEUP_NONE,	/* No preemption. */
8672 	PREEMPT_WAKEUP_SHORT,	/* Ignore slice protection. */
8673 	PREEMPT_WAKEUP_PICK,	/* Let __pick_eevdf() decide. */
8674 	PREEMPT_WAKEUP_RESCHED,	/* Force reschedule. */
8675 };
8676 
8677 static inline bool
8678 set_preempt_buddy(struct cfs_rq *cfs_rq, int wake_flags,
8679 		  struct sched_entity *pse, struct sched_entity *se)
8680 {
8681 	/*
8682 	 * Keep existing buddy if the deadline is sooner than pse.
8683 	 * The older buddy may be cache cold and completely unrelated
8684 	 * to the current wakeup but that is unpredictable where as
8685 	 * obeying the deadline is more in line with EEVDF objectives.
8686 	 */
8687 	if (cfs_rq->next && entity_before(cfs_rq->next, pse))
8688 		return false;
8689 
8690 	set_next_buddy(pse);
8691 	return true;
8692 }
8693 
8694 /*
8695  * WF_SYNC|WF_TTWU indicates the waker expects to sleep but it is not
8696  * strictly enforced because the hint is either misunderstood or
8697  * multiple tasks must be woken up.
8698  */
8699 static inline enum preempt_wakeup_action
8700 preempt_sync(struct rq *rq, int wake_flags,
8701 	     struct sched_entity *pse, struct sched_entity *se)
8702 {
8703 	u64 threshold, delta;
8704 
8705 	/*
8706 	 * WF_SYNC without WF_TTWU is not expected so warn if it happens even
8707 	 * though it is likely harmless.
8708 	 */
8709 	WARN_ON_ONCE(!(wake_flags & WF_TTWU));
8710 
8711 	threshold = sysctl_sched_migration_cost;
8712 	delta = rq_clock_task(rq) - se->exec_start;
8713 	if ((s64)delta < 0)
8714 		delta = 0;
8715 
8716 	/*
8717 	 * WF_RQ_SELECTED implies the tasks are stacking on a CPU when they
8718 	 * could run on other CPUs. Reduce the threshold before preemption is
8719 	 * allowed to an arbitrary lower value as it is more likely (but not
8720 	 * guaranteed) the waker requires the wakee to finish.
8721 	 */
8722 	if (wake_flags & WF_RQ_SELECTED)
8723 		threshold >>= 2;
8724 
8725 	/*
8726 	 * As WF_SYNC is not strictly obeyed, allow some runtime for batch
8727 	 * wakeups to be issued.
8728 	 */
8729 	if (entity_before(pse, se) && delta >= threshold)
8730 		return PREEMPT_WAKEUP_RESCHED;
8731 
8732 	return PREEMPT_WAKEUP_NONE;
8733 }
8734 
8735 /*
8736  * Preempt the current task with a newly woken task if needed:
8737  */
8738 static void wakeup_preempt_fair(struct rq *rq, struct task_struct *p, int wake_flags)
8739 {
8740 	enum preempt_wakeup_action preempt_action = PREEMPT_WAKEUP_PICK;
8741 	struct task_struct *donor = rq->donor;
8742 	struct sched_entity *se = &donor->se, *pse = &p->se;
8743 	struct cfs_rq *cfs_rq = task_cfs_rq(donor);
8744 	int cse_is_idle, pse_is_idle;
8745 
8746 	/*
8747 	 * XXX Getting preempted by higher class, try and find idle CPU?
8748 	 */
8749 	if (p->sched_class != &fair_sched_class)
8750 		return;
8751 
8752 	if (unlikely(se == pse))
8753 		return;
8754 
8755 	/*
8756 	 * This is possible from callers such as attach_tasks(), in which we
8757 	 * unconditionally wakeup_preempt() after an enqueue (which may have
8758 	 * lead to a throttle).  This both saves work and prevents false
8759 	 * next-buddy nomination below.
8760 	 */
8761 	if (task_is_throttled(p))
8762 		return;
8763 
8764 	/*
8765 	 * We can come here with TIF_NEED_RESCHED already set from new task
8766 	 * wake up path.
8767 	 *
8768 	 * Note: this also catches the edge-case of curr being in a throttled
8769 	 * group (e.g. via set_curr_task), since update_curr() (in the
8770 	 * enqueue of curr) will have resulted in resched being set.  This
8771 	 * prevents us from potentially nominating it as a false LAST_BUDDY
8772 	 * below.
8773 	 */
8774 	if (test_tsk_need_resched(rq->curr))
8775 		return;
8776 
8777 	if (!sched_feat(WAKEUP_PREEMPTION))
8778 		return;
8779 
8780 	find_matching_se(&se, &pse);
8781 	WARN_ON_ONCE(!pse);
8782 
8783 	cse_is_idle = se_is_idle(se);
8784 	pse_is_idle = se_is_idle(pse);
8785 
8786 	/*
8787 	 * Preempt an idle entity in favor of a non-idle entity (and don't preempt
8788 	 * in the inverse case).
8789 	 */
8790 	if (cse_is_idle && !pse_is_idle) {
8791 		/*
8792 		 * When non-idle entity preempt an idle entity,
8793 		 * don't give idle entity slice protection.
8794 		 */
8795 		preempt_action = PREEMPT_WAKEUP_SHORT;
8796 		goto preempt;
8797 	}
8798 
8799 	if (cse_is_idle != pse_is_idle)
8800 		return;
8801 
8802 	/*
8803 	 * BATCH and IDLE tasks do not preempt others.
8804 	 */
8805 	if (unlikely(!normal_policy(p->policy)))
8806 		return;
8807 
8808 	cfs_rq = cfs_rq_of(se);
8809 	update_curr(cfs_rq);
8810 	/*
8811 	 * If @p has a shorter slice than current and @p is eligible, override
8812 	 * current's slice protection in order to allow preemption.
8813 	 */
8814 	if (sched_feat(PREEMPT_SHORT) && (pse->slice < se->slice)) {
8815 		preempt_action = PREEMPT_WAKEUP_SHORT;
8816 		goto pick;
8817 	}
8818 
8819 	/*
8820 	 * Ignore wakee preemption on WF_FORK as it is less likely that
8821 	 * there is shared data as exec often follow fork. Do not
8822 	 * preempt for tasks that are sched_delayed as it would violate
8823 	 * EEVDF to forcibly queue an ineligible task.
8824 	 */
8825 	if ((wake_flags & WF_FORK) || pse->sched_delayed)
8826 		return;
8827 
8828 	/* Prefer picking wakee soon if appropriate. */
8829 	if (sched_feat(NEXT_BUDDY) &&
8830 	    set_preempt_buddy(cfs_rq, wake_flags, pse, se)) {
8831 
8832 		/*
8833 		 * Decide whether to obey WF_SYNC hint for a new buddy. Old
8834 		 * buddies are ignored as they may not be relevant to the
8835 		 * waker and less likely to be cache hot.
8836 		 */
8837 		if (wake_flags & WF_SYNC)
8838 			preempt_action = preempt_sync(rq, wake_flags, pse, se);
8839 	}
8840 
8841 	switch (preempt_action) {
8842 	case PREEMPT_WAKEUP_NONE:
8843 		return;
8844 	case PREEMPT_WAKEUP_RESCHED:
8845 		goto preempt;
8846 	case PREEMPT_WAKEUP_SHORT:
8847 		fallthrough;
8848 	case PREEMPT_WAKEUP_PICK:
8849 		break;
8850 	}
8851 
8852 pick:
8853 	/*
8854 	 * If @p has become the most eligible task, force preemption.
8855 	 */
8856 	if (__pick_eevdf(cfs_rq, preempt_action != PREEMPT_WAKEUP_SHORT) == pse)
8857 		goto preempt;
8858 
8859 	if (sched_feat(RUN_TO_PARITY))
8860 		update_protect_slice(cfs_rq, se);
8861 
8862 	return;
8863 
8864 preempt:
8865 	if (preempt_action == PREEMPT_WAKEUP_SHORT)
8866 		cancel_protect_slice(se);
8867 
8868 	resched_curr_lazy(rq);
8869 }
8870 
8871 static struct task_struct *pick_task_fair(struct rq *rq, struct rq_flags *rf)
8872 {
8873 	struct sched_entity *se;
8874 	struct cfs_rq *cfs_rq;
8875 	struct task_struct *p;
8876 	bool throttled;
8877 
8878 again:
8879 	cfs_rq = &rq->cfs;
8880 	if (!cfs_rq->nr_queued)
8881 		return NULL;
8882 
8883 	throttled = false;
8884 
8885 	do {
8886 		/* Might not have done put_prev_entity() */
8887 		if (cfs_rq->curr && cfs_rq->curr->on_rq)
8888 			update_curr(cfs_rq);
8889 
8890 		throttled |= check_cfs_rq_runtime(cfs_rq);
8891 
8892 		se = pick_next_entity(rq, cfs_rq);
8893 		if (!se)
8894 			goto again;
8895 		cfs_rq = group_cfs_rq(se);
8896 	} while (cfs_rq);
8897 
8898 	p = task_of(se);
8899 	if (unlikely(throttled))
8900 		task_throttle_setup_work(p);
8901 	return p;
8902 }
8903 
8904 static void __set_next_task_fair(struct rq *rq, struct task_struct *p, bool first);
8905 static void set_next_task_fair(struct rq *rq, struct task_struct *p, bool first);
8906 
8907 struct task_struct *
8908 pick_next_task_fair(struct rq *rq, struct task_struct *prev, struct rq_flags *rf)
8909 	__must_hold(__rq_lockp(rq))
8910 {
8911 	struct sched_entity *se;
8912 	struct task_struct *p;
8913 	int new_tasks;
8914 
8915 again:
8916 	p = pick_task_fair(rq, rf);
8917 	if (!p)
8918 		goto idle;
8919 	se = &p->se;
8920 
8921 #ifdef CONFIG_FAIR_GROUP_SCHED
8922 	if (prev->sched_class != &fair_sched_class)
8923 		goto simple;
8924 
8925 	__put_prev_set_next_dl_server(rq, prev, p);
8926 
8927 	/*
8928 	 * Because of the set_next_buddy() in dequeue_task_fair() it is rather
8929 	 * likely that a next task is from the same cgroup as the current.
8930 	 *
8931 	 * Therefore attempt to avoid putting and setting the entire cgroup
8932 	 * hierarchy, only change the part that actually changes.
8933 	 *
8934 	 * Since we haven't yet done put_prev_entity and if the selected task
8935 	 * is a different task than we started out with, try and touch the
8936 	 * least amount of cfs_rqs.
8937 	 */
8938 	if (prev != p) {
8939 		struct sched_entity *pse = &prev->se;
8940 		struct cfs_rq *cfs_rq;
8941 
8942 		while (!(cfs_rq = is_same_group(se, pse))) {
8943 			int se_depth = se->depth;
8944 			int pse_depth = pse->depth;
8945 
8946 			if (se_depth <= pse_depth) {
8947 				put_prev_entity(cfs_rq_of(pse), pse);
8948 				pse = parent_entity(pse);
8949 			}
8950 			if (se_depth >= pse_depth) {
8951 				set_next_entity(cfs_rq_of(se), se);
8952 				se = parent_entity(se);
8953 			}
8954 		}
8955 
8956 		put_prev_entity(cfs_rq, pse);
8957 		set_next_entity(cfs_rq, se);
8958 
8959 		__set_next_task_fair(rq, p, true);
8960 	}
8961 
8962 	return p;
8963 
8964 simple:
8965 #endif /* CONFIG_FAIR_GROUP_SCHED */
8966 	put_prev_set_next_task(rq, prev, p);
8967 	return p;
8968 
8969 idle:
8970 	if (rf) {
8971 		new_tasks = sched_balance_newidle(rq, rf);
8972 
8973 		/*
8974 		 * Because sched_balance_newidle() releases (and re-acquires)
8975 		 * rq->lock, it is possible for any higher priority task to
8976 		 * appear. In that case we must re-start the pick_next_entity()
8977 		 * loop.
8978 		 */
8979 		if (new_tasks < 0)
8980 			return RETRY_TASK;
8981 
8982 		if (new_tasks > 0)
8983 			goto again;
8984 	}
8985 
8986 	return NULL;
8987 }
8988 
8989 static struct task_struct *
8990 fair_server_pick_task(struct sched_dl_entity *dl_se, struct rq_flags *rf)
8991 {
8992 	return pick_task_fair(dl_se->rq, rf);
8993 }
8994 
8995 void fair_server_init(struct rq *rq)
8996 {
8997 	struct sched_dl_entity *dl_se = &rq->fair_server;
8998 
8999 	init_dl_entity(dl_se);
9000 
9001 	dl_server_init(dl_se, rq, fair_server_pick_task);
9002 }
9003 
9004 /*
9005  * Account for a descheduled task:
9006  */
9007 static void put_prev_task_fair(struct rq *rq, struct task_struct *prev, struct task_struct *next)
9008 {
9009 	struct sched_entity *se = &prev->se;
9010 	struct cfs_rq *cfs_rq;
9011 
9012 	for_each_sched_entity(se) {
9013 		cfs_rq = cfs_rq_of(se);
9014 		put_prev_entity(cfs_rq, se);
9015 	}
9016 }
9017 
9018 /*
9019  * sched_yield() is very simple
9020  */
9021 static void yield_task_fair(struct rq *rq)
9022 {
9023 	struct task_struct *curr = rq->donor;
9024 	struct cfs_rq *cfs_rq = task_cfs_rq(curr);
9025 	struct sched_entity *se = &curr->se;
9026 
9027 	/*
9028 	 * Are we the only task in the tree?
9029 	 */
9030 	if (unlikely(rq->nr_running == 1))
9031 		return;
9032 
9033 	clear_buddies(cfs_rq, se);
9034 
9035 	update_rq_clock(rq);
9036 	/*
9037 	 * Update run-time statistics of the 'current'.
9038 	 */
9039 	update_curr(cfs_rq);
9040 	/*
9041 	 * Tell update_rq_clock() that we've just updated,
9042 	 * so we don't do microscopic update in schedule()
9043 	 * and double the fastpath cost.
9044 	 */
9045 	rq_clock_skip_update(rq);
9046 
9047 	/*
9048 	 * Forfeit the remaining vruntime, only if the entity is eligible. This
9049 	 * condition is necessary because in core scheduling we prefer to run
9050 	 * ineligible tasks rather than force idling. If this happens we may
9051 	 * end up in a loop where the core scheduler picks the yielding task,
9052 	 * which yields immediately again; without the condition the vruntime
9053 	 * ends up quickly running away.
9054 	 */
9055 	if (entity_eligible(cfs_rq, se)) {
9056 		se->vruntime = se->deadline;
9057 		se->deadline += calc_delta_fair(se->slice, se);
9058 	}
9059 }
9060 
9061 static bool yield_to_task_fair(struct rq *rq, struct task_struct *p)
9062 {
9063 	struct sched_entity *se = &p->se;
9064 
9065 	/* !se->on_rq also covers throttled task */
9066 	if (!se->on_rq)
9067 		return false;
9068 
9069 	/* Tell the scheduler that we'd really like se to run next. */
9070 	set_next_buddy(se);
9071 
9072 	yield_task_fair(rq);
9073 
9074 	return true;
9075 }
9076 
9077 /**************************************************
9078  * Fair scheduling class load-balancing methods.
9079  *
9080  * BASICS
9081  *
9082  * The purpose of load-balancing is to achieve the same basic fairness the
9083  * per-CPU scheduler provides, namely provide a proportional amount of compute
9084  * time to each task. This is expressed in the following equation:
9085  *
9086  *   W_i,n/P_i == W_j,n/P_j for all i,j                               (1)
9087  *
9088  * Where W_i,n is the n-th weight average for CPU i. The instantaneous weight
9089  * W_i,0 is defined as:
9090  *
9091  *   W_i,0 = \Sum_j w_i,j                                             (2)
9092  *
9093  * Where w_i,j is the weight of the j-th runnable task on CPU i. This weight
9094  * is derived from the nice value as per sched_prio_to_weight[].
9095  *
9096  * The weight average is an exponential decay average of the instantaneous
9097  * weight:
9098  *
9099  *   W'_i,n = (2^n - 1) / 2^n * W_i,n + 1 / 2^n * W_i,0               (3)
9100  *
9101  * C_i is the compute capacity of CPU i, typically it is the
9102  * fraction of 'recent' time available for SCHED_OTHER task execution. But it
9103  * can also include other factors [XXX].
9104  *
9105  * To achieve this balance we define a measure of imbalance which follows
9106  * directly from (1):
9107  *
9108  *   imb_i,j = max{ avg(W/C), W_i/C_i } - min{ avg(W/C), W_j/C_j }    (4)
9109  *
9110  * We them move tasks around to minimize the imbalance. In the continuous
9111  * function space it is obvious this converges, in the discrete case we get
9112  * a few fun cases generally called infeasible weight scenarios.
9113  *
9114  * [XXX expand on:
9115  *     - infeasible weights;
9116  *     - local vs global optima in the discrete case. ]
9117  *
9118  *
9119  * SCHED DOMAINS
9120  *
9121  * In order to solve the imbalance equation (4), and avoid the obvious O(n^2)
9122  * for all i,j solution, we create a tree of CPUs that follows the hardware
9123  * topology where each level pairs two lower groups (or better). This results
9124  * in O(log n) layers. Furthermore we reduce the number of CPUs going up the
9125  * tree to only the first of the previous level and we decrease the frequency
9126  * of load-balance at each level inversely proportional to the number of CPUs in
9127  * the groups.
9128  *
9129  * This yields:
9130  *
9131  *     log_2 n     1     n
9132  *   \Sum       { --- * --- * 2^i } = O(n)                            (5)
9133  *     i = 0      2^i   2^i
9134  *                               `- size of each group
9135  *         |         |     `- number of CPUs doing load-balance
9136  *         |         `- freq
9137  *         `- sum over all levels
9138  *
9139  * Coupled with a limit on how many tasks we can migrate every balance pass,
9140  * this makes (5) the runtime complexity of the balancer.
9141  *
9142  * An important property here is that each CPU is still (indirectly) connected
9143  * to every other CPU in at most O(log n) steps:
9144  *
9145  * The adjacency matrix of the resulting graph is given by:
9146  *
9147  *             log_2 n
9148  *   A_i,j = \Union     (i % 2^k == 0) && i / 2^(k+1) == j / 2^(k+1)  (6)
9149  *             k = 0
9150  *
9151  * And you'll find that:
9152  *
9153  *   A^(log_2 n)_i,j != 0  for all i,j                                (7)
9154  *
9155  * Showing there's indeed a path between every CPU in at most O(log n) steps.
9156  * The task movement gives a factor of O(m), giving a convergence complexity
9157  * of:
9158  *
9159  *   O(nm log n),  n := nr_cpus, m := nr_tasks                        (8)
9160  *
9161  *
9162  * WORK CONSERVING
9163  *
9164  * In order to avoid CPUs going idle while there's still work to do, new idle
9165  * balancing is more aggressive and has the newly idle CPU iterate up the domain
9166  * tree itself instead of relying on other CPUs to bring it work.
9167  *
9168  * This adds some complexity to both (5) and (8) but it reduces the total idle
9169  * time.
9170  *
9171  * [XXX more?]
9172  *
9173  *
9174  * CGROUPS
9175  *
9176  * Cgroups make a horror show out of (2), instead of a simple sum we get:
9177  *
9178  *                                s_k,i
9179  *   W_i,0 = \Sum_j \Prod_k w_k * -----                               (9)
9180  *                                 S_k
9181  *
9182  * Where
9183  *
9184  *   s_k,i = \Sum_j w_i,j,k  and  S_k = \Sum_i s_k,i                 (10)
9185  *
9186  * w_i,j,k is the weight of the j-th runnable task in the k-th cgroup on CPU i.
9187  *
9188  * The big problem is S_k, its a global sum needed to compute a local (W_i)
9189  * property.
9190  *
9191  * [XXX write more on how we solve this.. _after_ merging pjt's patches that
9192  *      rewrite all of this once again.]
9193  */
9194 
9195 static unsigned long __read_mostly max_load_balance_interval = HZ/10;
9196 
9197 enum fbq_type { regular, remote, all };
9198 
9199 /*
9200  * 'group_type' describes the group of CPUs at the moment of load balancing.
9201  *
9202  * The enum is ordered by pulling priority, with the group with lowest priority
9203  * first so the group_type can simply be compared when selecting the busiest
9204  * group. See update_sd_pick_busiest().
9205  */
9206 enum group_type {
9207 	/* The group has spare capacity that can be used to run more tasks.  */
9208 	group_has_spare = 0,
9209 	/*
9210 	 * The group is fully used and the tasks don't compete for more CPU
9211 	 * cycles. Nevertheless, some tasks might wait before running.
9212 	 */
9213 	group_fully_busy,
9214 	/*
9215 	 * One task doesn't fit with CPU's capacity and must be migrated to a
9216 	 * more powerful CPU.
9217 	 */
9218 	group_misfit_task,
9219 	/*
9220 	 * Balance SMT group that's fully busy. Can benefit from migration
9221 	 * a task on SMT with busy sibling to another CPU on idle core.
9222 	 */
9223 	group_smt_balance,
9224 	/*
9225 	 * SD_ASYM_PACKING only: One local CPU with higher capacity is available,
9226 	 * and the task should be migrated to it instead of running on the
9227 	 * current CPU.
9228 	 */
9229 	group_asym_packing,
9230 	/*
9231 	 * The tasks' affinity constraints previously prevented the scheduler
9232 	 * from balancing the load across the system.
9233 	 */
9234 	group_imbalanced,
9235 	/*
9236 	 * The CPU is overloaded and can't provide expected CPU cycles to all
9237 	 * tasks.
9238 	 */
9239 	group_overloaded
9240 };
9241 
9242 enum migration_type {
9243 	migrate_load = 0,
9244 	migrate_util,
9245 	migrate_task,
9246 	migrate_misfit
9247 };
9248 
9249 #define LBF_ALL_PINNED	0x01
9250 #define LBF_NEED_BREAK	0x02
9251 #define LBF_DST_PINNED  0x04
9252 #define LBF_SOME_PINNED	0x08
9253 #define LBF_ACTIVE_LB	0x10
9254 
9255 struct lb_env {
9256 	struct sched_domain	*sd;
9257 
9258 	struct rq		*src_rq;
9259 	int			src_cpu;
9260 
9261 	int			dst_cpu;
9262 	struct rq		*dst_rq;
9263 
9264 	struct cpumask		*dst_grpmask;
9265 	int			new_dst_cpu;
9266 	enum cpu_idle_type	idle;
9267 	long			imbalance;
9268 	/* The set of CPUs under consideration for load-balancing */
9269 	struct cpumask		*cpus;
9270 
9271 	unsigned int		flags;
9272 
9273 	unsigned int		loop;
9274 	unsigned int		loop_break;
9275 	unsigned int		loop_max;
9276 
9277 	enum fbq_type		fbq_type;
9278 	enum migration_type	migration_type;
9279 	struct list_head	tasks;
9280 };
9281 
9282 /*
9283  * Is this task likely cache-hot:
9284  */
9285 static int task_hot(struct task_struct *p, struct lb_env *env)
9286 {
9287 	s64 delta;
9288 
9289 	lockdep_assert_rq_held(env->src_rq);
9290 
9291 	if (p->sched_class != &fair_sched_class)
9292 		return 0;
9293 
9294 	if (unlikely(task_has_idle_policy(p)))
9295 		return 0;
9296 
9297 	/* SMT siblings share cache */
9298 	if (env->sd->flags & SD_SHARE_CPUCAPACITY)
9299 		return 0;
9300 
9301 	/*
9302 	 * Buddy candidates are cache hot:
9303 	 */
9304 	if (sched_feat(CACHE_HOT_BUDDY) && env->dst_rq->nr_running &&
9305 	    (&p->se == cfs_rq_of(&p->se)->next))
9306 		return 1;
9307 
9308 	if (sysctl_sched_migration_cost == -1)
9309 		return 1;
9310 
9311 	/*
9312 	 * Don't migrate task if the task's cookie does not match
9313 	 * with the destination CPU's core cookie.
9314 	 */
9315 	if (!sched_core_cookie_match(cpu_rq(env->dst_cpu), p))
9316 		return 1;
9317 
9318 	if (sysctl_sched_migration_cost == 0)
9319 		return 0;
9320 
9321 	delta = rq_clock_task(env->src_rq) - p->se.exec_start;
9322 
9323 	return delta < (s64)sysctl_sched_migration_cost;
9324 }
9325 
9326 #ifdef CONFIG_NUMA_BALANCING
9327 /*
9328  * Returns a positive value, if task migration degrades locality.
9329  * Returns 0, if task migration is not affected by locality.
9330  * Returns a negative value, if task migration improves locality i.e migration preferred.
9331  */
9332 static long migrate_degrades_locality(struct task_struct *p, struct lb_env *env)
9333 {
9334 	struct numa_group *numa_group = rcu_dereference_all(p->numa_group);
9335 	unsigned long src_weight, dst_weight;
9336 	int src_nid, dst_nid, dist;
9337 
9338 	if (!static_branch_likely(&sched_numa_balancing))
9339 		return 0;
9340 
9341 	if (!p->numa_faults || !(env->sd->flags & SD_NUMA))
9342 		return 0;
9343 
9344 	src_nid = cpu_to_node(env->src_cpu);
9345 	dst_nid = cpu_to_node(env->dst_cpu);
9346 
9347 	if (src_nid == dst_nid)
9348 		return 0;
9349 
9350 	/* Migrating away from the preferred node is always bad. */
9351 	if (src_nid == p->numa_preferred_nid) {
9352 		if (env->src_rq->nr_running > env->src_rq->nr_preferred_running)
9353 			return 1;
9354 		else
9355 			return 0;
9356 	}
9357 
9358 	/* Encourage migration to the preferred node. */
9359 	if (dst_nid == p->numa_preferred_nid)
9360 		return -1;
9361 
9362 	/* Leaving a core idle is often worse than degrading locality. */
9363 	if (env->idle == CPU_IDLE)
9364 		return 0;
9365 
9366 	dist = node_distance(src_nid, dst_nid);
9367 	if (numa_group) {
9368 		src_weight = group_weight(p, src_nid, dist);
9369 		dst_weight = group_weight(p, dst_nid, dist);
9370 	} else {
9371 		src_weight = task_weight(p, src_nid, dist);
9372 		dst_weight = task_weight(p, dst_nid, dist);
9373 	}
9374 
9375 	return src_weight - dst_weight;
9376 }
9377 
9378 #else /* !CONFIG_NUMA_BALANCING: */
9379 static inline long migrate_degrades_locality(struct task_struct *p,
9380 					     struct lb_env *env)
9381 {
9382 	return 0;
9383 }
9384 #endif /* !CONFIG_NUMA_BALANCING */
9385 
9386 /*
9387  * Check whether the task is ineligible on the destination cpu
9388  *
9389  * When the PLACE_LAG scheduling feature is enabled and
9390  * dst_cfs_rq->nr_queued is greater than 1, if the task
9391  * is ineligible, it will also be ineligible when
9392  * it is migrated to the destination cpu.
9393  */
9394 static inline int task_is_ineligible_on_dst_cpu(struct task_struct *p, int dest_cpu)
9395 {
9396 	struct cfs_rq *dst_cfs_rq;
9397 
9398 #ifdef CONFIG_FAIR_GROUP_SCHED
9399 	dst_cfs_rq = task_group(p)->cfs_rq[dest_cpu];
9400 #else
9401 	dst_cfs_rq = &cpu_rq(dest_cpu)->cfs;
9402 #endif
9403 	if (sched_feat(PLACE_LAG) && dst_cfs_rq->nr_queued &&
9404 	    !entity_eligible(task_cfs_rq(p), &p->se))
9405 		return 1;
9406 
9407 	return 0;
9408 }
9409 
9410 /*
9411  * can_migrate_task - may task p from runqueue rq be migrated to this_cpu?
9412  */
9413 static
9414 int can_migrate_task(struct task_struct *p, struct lb_env *env)
9415 {
9416 	long degrades, hot;
9417 
9418 	lockdep_assert_rq_held(env->src_rq);
9419 	if (p->sched_task_hot)
9420 		p->sched_task_hot = 0;
9421 
9422 	/*
9423 	 * We do not migrate tasks that are:
9424 	 * 1) delayed dequeued unless we migrate load, or
9425 	 * 2) target cfs_rq is in throttled hierarchy, or
9426 	 * 3) cannot be migrated to this CPU due to cpus_ptr, or
9427 	 * 4) running (obviously), or
9428 	 * 5) are cache-hot on their current CPU, or
9429 	 * 6) are blocked on mutexes (if SCHED_PROXY_EXEC is enabled)
9430 	 */
9431 	if ((p->se.sched_delayed) && (env->migration_type != migrate_load))
9432 		return 0;
9433 
9434 	if (lb_throttled_hierarchy(p, env->dst_cpu))
9435 		return 0;
9436 
9437 	/*
9438 	 * We want to prioritize the migration of eligible tasks.
9439 	 * For ineligible tasks we soft-limit them and only allow
9440 	 * them to migrate when nr_balance_failed is non-zero to
9441 	 * avoid load-balancing trying very hard to balance the load.
9442 	 */
9443 	if (!env->sd->nr_balance_failed &&
9444 	    task_is_ineligible_on_dst_cpu(p, env->dst_cpu))
9445 		return 0;
9446 
9447 	/* Disregard percpu kthreads; they are where they need to be. */
9448 	if (kthread_is_per_cpu(p))
9449 		return 0;
9450 
9451 	if (task_is_blocked(p))
9452 		return 0;
9453 
9454 	if (!cpumask_test_cpu(env->dst_cpu, p->cpus_ptr)) {
9455 		int cpu;
9456 
9457 		schedstat_inc(p->stats.nr_failed_migrations_affine);
9458 
9459 		env->flags |= LBF_SOME_PINNED;
9460 
9461 		/*
9462 		 * Remember if this task can be migrated to any other CPU in
9463 		 * our sched_group. We may want to revisit it if we couldn't
9464 		 * meet load balance goals by pulling other tasks on src_cpu.
9465 		 *
9466 		 * Avoid computing new_dst_cpu
9467 		 * - for NEWLY_IDLE
9468 		 * - if we have already computed one in current iteration
9469 		 * - if it's an active balance
9470 		 */
9471 		if (env->idle == CPU_NEWLY_IDLE ||
9472 		    env->flags & (LBF_DST_PINNED | LBF_ACTIVE_LB))
9473 			return 0;
9474 
9475 		/* Prevent to re-select dst_cpu via env's CPUs: */
9476 		cpu = cpumask_first_and_and(env->dst_grpmask, env->cpus, p->cpus_ptr);
9477 
9478 		if (cpu < nr_cpu_ids) {
9479 			env->flags |= LBF_DST_PINNED;
9480 			env->new_dst_cpu = cpu;
9481 		}
9482 
9483 		return 0;
9484 	}
9485 
9486 	/* Record that we found at least one task that could run on dst_cpu */
9487 	env->flags &= ~LBF_ALL_PINNED;
9488 
9489 	if (task_on_cpu(env->src_rq, p) ||
9490 	    task_current_donor(env->src_rq, p)) {
9491 		schedstat_inc(p->stats.nr_failed_migrations_running);
9492 		return 0;
9493 	}
9494 
9495 	/*
9496 	 * Aggressive migration if:
9497 	 * 1) active balance
9498 	 * 2) destination numa is preferred
9499 	 * 3) task is cache cold, or
9500 	 * 4) too many balance attempts have failed.
9501 	 */
9502 	if (env->flags & LBF_ACTIVE_LB)
9503 		return 1;
9504 
9505 	degrades = migrate_degrades_locality(p, env);
9506 	if (!degrades)
9507 		hot = task_hot(p, env);
9508 	else
9509 		hot = degrades > 0;
9510 
9511 	if (!hot || env->sd->nr_balance_failed > env->sd->cache_nice_tries) {
9512 		if (hot)
9513 			p->sched_task_hot = 1;
9514 		return 1;
9515 	}
9516 
9517 	schedstat_inc(p->stats.nr_failed_migrations_hot);
9518 	return 0;
9519 }
9520 
9521 /*
9522  * detach_task() -- detach the task for the migration specified in env
9523  */
9524 static void detach_task(struct task_struct *p, struct lb_env *env)
9525 {
9526 	lockdep_assert_rq_held(env->src_rq);
9527 
9528 	if (p->sched_task_hot) {
9529 		p->sched_task_hot = 0;
9530 		schedstat_inc(env->sd->lb_hot_gained[env->idle]);
9531 		schedstat_inc(p->stats.nr_forced_migrations);
9532 	}
9533 
9534 	WARN_ON(task_current(env->src_rq, p));
9535 	WARN_ON(task_current_donor(env->src_rq, p));
9536 
9537 	deactivate_task(env->src_rq, p, DEQUEUE_NOCLOCK);
9538 	set_task_cpu(p, env->dst_cpu);
9539 }
9540 
9541 /*
9542  * detach_one_task() -- tries to dequeue exactly one task from env->src_rq, as
9543  * part of active balancing operations within "domain".
9544  *
9545  * Returns a task if successful and NULL otherwise.
9546  */
9547 static struct task_struct *detach_one_task(struct lb_env *env)
9548 {
9549 	struct task_struct *p;
9550 
9551 	lockdep_assert_rq_held(env->src_rq);
9552 
9553 	list_for_each_entry_reverse(p,
9554 			&env->src_rq->cfs_tasks, se.group_node) {
9555 		if (!can_migrate_task(p, env))
9556 			continue;
9557 
9558 		detach_task(p, env);
9559 
9560 		/*
9561 		 * Right now, this is only the second place where
9562 		 * lb_gained[env->idle] is updated (other is detach_tasks)
9563 		 * so we can safely collect stats here rather than
9564 		 * inside detach_tasks().
9565 		 */
9566 		schedstat_inc(env->sd->lb_gained[env->idle]);
9567 		return p;
9568 	}
9569 	return NULL;
9570 }
9571 
9572 /*
9573  * detach_tasks() -- tries to detach up to imbalance load/util/tasks from
9574  * busiest_rq, as part of a balancing operation within domain "sd".
9575  *
9576  * Returns number of detached tasks if successful and 0 otherwise.
9577  */
9578 static int detach_tasks(struct lb_env *env)
9579 {
9580 	struct list_head *tasks = &env->src_rq->cfs_tasks;
9581 	unsigned long util, load;
9582 	struct task_struct *p;
9583 	int detached = 0;
9584 
9585 	lockdep_assert_rq_held(env->src_rq);
9586 
9587 	/*
9588 	 * Source run queue has been emptied by another CPU, clear
9589 	 * LBF_ALL_PINNED flag as we will not test any task.
9590 	 */
9591 	if (env->src_rq->nr_running <= 1) {
9592 		env->flags &= ~LBF_ALL_PINNED;
9593 		return 0;
9594 	}
9595 
9596 	if (env->imbalance <= 0)
9597 		return 0;
9598 
9599 	while (!list_empty(tasks)) {
9600 		/*
9601 		 * We don't want to steal all, otherwise we may be treated likewise,
9602 		 * which could at worst lead to a livelock crash.
9603 		 */
9604 		if (env->idle && env->src_rq->nr_running <= 1)
9605 			break;
9606 
9607 		env->loop++;
9608 		/* We've more or less seen every task there is, call it quits */
9609 		if (env->loop > env->loop_max)
9610 			break;
9611 
9612 		/* take a breather every nr_migrate tasks */
9613 		if (env->loop > env->loop_break) {
9614 			env->loop_break += SCHED_NR_MIGRATE_BREAK;
9615 			env->flags |= LBF_NEED_BREAK;
9616 			break;
9617 		}
9618 
9619 		p = list_last_entry(tasks, struct task_struct, se.group_node);
9620 
9621 		if (!can_migrate_task(p, env))
9622 			goto next;
9623 
9624 		switch (env->migration_type) {
9625 		case migrate_load:
9626 			/*
9627 			 * Depending of the number of CPUs and tasks and the
9628 			 * cgroup hierarchy, task_h_load() can return a null
9629 			 * value. Make sure that env->imbalance decreases
9630 			 * otherwise detach_tasks() will stop only after
9631 			 * detaching up to loop_max tasks.
9632 			 */
9633 			load = max_t(unsigned long, task_h_load(p), 1);
9634 
9635 			if (sched_feat(LB_MIN) &&
9636 			    load < 16 && !env->sd->nr_balance_failed)
9637 				goto next;
9638 
9639 			/*
9640 			 * Make sure that we don't migrate too much load.
9641 			 * Nevertheless, let relax the constraint if
9642 			 * scheduler fails to find a good waiting task to
9643 			 * migrate.
9644 			 */
9645 			if (shr_bound(load, env->sd->nr_balance_failed) > env->imbalance)
9646 				goto next;
9647 
9648 			env->imbalance -= load;
9649 			break;
9650 
9651 		case migrate_util:
9652 			util = task_util_est(p);
9653 
9654 			if (shr_bound(util, env->sd->nr_balance_failed) > env->imbalance)
9655 				goto next;
9656 
9657 			env->imbalance -= util;
9658 			break;
9659 
9660 		case migrate_task:
9661 			env->imbalance--;
9662 			break;
9663 
9664 		case migrate_misfit:
9665 			/* This is not a misfit task */
9666 			if (task_fits_cpu(p, env->src_cpu))
9667 				goto next;
9668 
9669 			env->imbalance = 0;
9670 			break;
9671 		}
9672 
9673 		detach_task(p, env);
9674 		list_add(&p->se.group_node, &env->tasks);
9675 
9676 		detached++;
9677 
9678 #ifdef CONFIG_PREEMPTION
9679 		/*
9680 		 * NEWIDLE balancing is a source of latency, so preemptible
9681 		 * kernels will stop after the first task is detached to minimize
9682 		 * the critical section.
9683 		 */
9684 		if (env->idle == CPU_NEWLY_IDLE)
9685 			break;
9686 #endif
9687 
9688 		/*
9689 		 * We only want to steal up to the prescribed amount of
9690 		 * load/util/tasks.
9691 		 */
9692 		if (env->imbalance <= 0)
9693 			break;
9694 
9695 		continue;
9696 next:
9697 		if (p->sched_task_hot)
9698 			schedstat_inc(p->stats.nr_failed_migrations_hot);
9699 
9700 		list_move(&p->se.group_node, tasks);
9701 	}
9702 
9703 	/*
9704 	 * Right now, this is one of only two places we collect this stat
9705 	 * so we can safely collect detach_one_task() stats here rather
9706 	 * than inside detach_one_task().
9707 	 */
9708 	schedstat_add(env->sd->lb_gained[env->idle], detached);
9709 
9710 	return detached;
9711 }
9712 
9713 /*
9714  * attach_task() -- attach the task detached by detach_task() to its new rq.
9715  */
9716 static void attach_task(struct rq *rq, struct task_struct *p)
9717 {
9718 	lockdep_assert_rq_held(rq);
9719 
9720 	WARN_ON_ONCE(task_rq(p) != rq);
9721 	activate_task(rq, p, ENQUEUE_NOCLOCK);
9722 	wakeup_preempt(rq, p, 0);
9723 }
9724 
9725 /*
9726  * attach_one_task() -- attaches the task returned from detach_one_task() to
9727  * its new rq.
9728  */
9729 static void attach_one_task(struct rq *rq, struct task_struct *p)
9730 {
9731 	struct rq_flags rf;
9732 
9733 	rq_lock(rq, &rf);
9734 	update_rq_clock(rq);
9735 	attach_task(rq, p);
9736 	rq_unlock(rq, &rf);
9737 }
9738 
9739 /*
9740  * attach_tasks() -- attaches all tasks detached by detach_tasks() to their
9741  * new rq.
9742  */
9743 static void attach_tasks(struct lb_env *env)
9744 {
9745 	struct list_head *tasks = &env->tasks;
9746 	struct task_struct *p;
9747 	struct rq_flags rf;
9748 
9749 	rq_lock(env->dst_rq, &rf);
9750 	update_rq_clock(env->dst_rq);
9751 
9752 	while (!list_empty(tasks)) {
9753 		p = list_first_entry(tasks, struct task_struct, se.group_node);
9754 		list_del_init(&p->se.group_node);
9755 
9756 		attach_task(env->dst_rq, p);
9757 	}
9758 
9759 	rq_unlock(env->dst_rq, &rf);
9760 }
9761 
9762 #ifdef CONFIG_NO_HZ_COMMON
9763 static inline bool cfs_rq_has_blocked_load(struct cfs_rq *cfs_rq)
9764 {
9765 	if (cfs_rq->avg.load_avg)
9766 		return true;
9767 
9768 	if (cfs_rq->avg.util_avg)
9769 		return true;
9770 
9771 	return false;
9772 }
9773 
9774 static inline bool others_have_blocked(struct rq *rq)
9775 {
9776 	if (cpu_util_rt(rq))
9777 		return true;
9778 
9779 	if (cpu_util_dl(rq))
9780 		return true;
9781 
9782 	if (hw_load_avg(rq))
9783 		return true;
9784 
9785 	if (cpu_util_irq(rq))
9786 		return true;
9787 
9788 	return false;
9789 }
9790 
9791 static inline void update_blocked_load_tick(struct rq *rq)
9792 {
9793 	WRITE_ONCE(rq->last_blocked_load_update_tick, jiffies);
9794 }
9795 
9796 static inline void update_has_blocked_load_status(struct rq *rq, bool has_blocked_load)
9797 {
9798 	if (!has_blocked_load)
9799 		rq->has_blocked_load = 0;
9800 }
9801 #else /* !CONFIG_NO_HZ_COMMON: */
9802 static inline bool cfs_rq_has_blocked_load(struct cfs_rq *cfs_rq) { return false; }
9803 static inline bool others_have_blocked(struct rq *rq) { return false; }
9804 static inline void update_blocked_load_tick(struct rq *rq) {}
9805 static inline void update_has_blocked_load_status(struct rq *rq, bool has_blocked_load) {}
9806 #endif /* !CONFIG_NO_HZ_COMMON */
9807 
9808 static bool __update_blocked_others(struct rq *rq, bool *done)
9809 {
9810 	bool updated;
9811 
9812 	/*
9813 	 * update_load_avg() can call cpufreq_update_util(). Make sure that RT,
9814 	 * DL and IRQ signals have been updated before updating CFS.
9815 	 */
9816 	updated = update_other_load_avgs(rq);
9817 
9818 	if (others_have_blocked(rq))
9819 		*done = false;
9820 
9821 	return updated;
9822 }
9823 
9824 #ifdef CONFIG_FAIR_GROUP_SCHED
9825 
9826 static bool __update_blocked_fair(struct rq *rq, bool *done)
9827 {
9828 	struct cfs_rq *cfs_rq, *pos;
9829 	bool decayed = false;
9830 	int cpu = cpu_of(rq);
9831 
9832 	/*
9833 	 * Iterates the task_group tree in a bottom up fashion, see
9834 	 * list_add_leaf_cfs_rq() for details.
9835 	 */
9836 	for_each_leaf_cfs_rq_safe(rq, cfs_rq, pos) {
9837 		struct sched_entity *se;
9838 
9839 		if (update_cfs_rq_load_avg(cfs_rq_clock_pelt(cfs_rq), cfs_rq)) {
9840 			update_tg_load_avg(cfs_rq);
9841 
9842 			if (cfs_rq->nr_queued == 0)
9843 				update_idle_cfs_rq_clock_pelt(cfs_rq);
9844 
9845 			if (cfs_rq == &rq->cfs)
9846 				decayed = true;
9847 		}
9848 
9849 		/* Propagate pending load changes to the parent, if any: */
9850 		se = cfs_rq->tg->se[cpu];
9851 		if (se && !skip_blocked_update(se))
9852 			update_load_avg(cfs_rq_of(se), se, UPDATE_TG);
9853 
9854 		/*
9855 		 * There can be a lot of idle CPU cgroups.  Don't let fully
9856 		 * decayed cfs_rqs linger on the list.
9857 		 */
9858 		if (cfs_rq_is_decayed(cfs_rq))
9859 			list_del_leaf_cfs_rq(cfs_rq);
9860 
9861 		/* Don't need periodic decay once load/util_avg are null */
9862 		if (cfs_rq_has_blocked_load(cfs_rq))
9863 			*done = false;
9864 	}
9865 
9866 	return decayed;
9867 }
9868 
9869 /*
9870  * Compute the hierarchical load factor for cfs_rq and all its ascendants.
9871  * This needs to be done in a top-down fashion because the load of a child
9872  * group is a fraction of its parents load.
9873  */
9874 static void update_cfs_rq_h_load(struct cfs_rq *cfs_rq)
9875 {
9876 	struct rq *rq = rq_of(cfs_rq);
9877 	struct sched_entity *se = cfs_rq->tg->se[cpu_of(rq)];
9878 	unsigned long now = jiffies;
9879 	unsigned long load;
9880 
9881 	if (cfs_rq->last_h_load_update == now)
9882 		return;
9883 
9884 	WRITE_ONCE(cfs_rq->h_load_next, NULL);
9885 	for_each_sched_entity(se) {
9886 		cfs_rq = cfs_rq_of(se);
9887 		WRITE_ONCE(cfs_rq->h_load_next, se);
9888 		if (cfs_rq->last_h_load_update == now)
9889 			break;
9890 	}
9891 
9892 	if (!se) {
9893 		cfs_rq->h_load = cfs_rq_load_avg(cfs_rq);
9894 		cfs_rq->last_h_load_update = now;
9895 	}
9896 
9897 	while ((se = READ_ONCE(cfs_rq->h_load_next)) != NULL) {
9898 		load = cfs_rq->h_load;
9899 		load = div64_ul(load * se->avg.load_avg,
9900 			cfs_rq_load_avg(cfs_rq) + 1);
9901 		cfs_rq = group_cfs_rq(se);
9902 		cfs_rq->h_load = load;
9903 		cfs_rq->last_h_load_update = now;
9904 	}
9905 }
9906 
9907 static unsigned long task_h_load(struct task_struct *p)
9908 {
9909 	struct cfs_rq *cfs_rq = task_cfs_rq(p);
9910 
9911 	update_cfs_rq_h_load(cfs_rq);
9912 	return div64_ul(p->se.avg.load_avg * cfs_rq->h_load,
9913 			cfs_rq_load_avg(cfs_rq) + 1);
9914 }
9915 #else /* !CONFIG_FAIR_GROUP_SCHED: */
9916 static bool __update_blocked_fair(struct rq *rq, bool *done)
9917 {
9918 	struct cfs_rq *cfs_rq = &rq->cfs;
9919 	bool decayed;
9920 
9921 	decayed = update_cfs_rq_load_avg(cfs_rq_clock_pelt(cfs_rq), cfs_rq);
9922 	if (cfs_rq_has_blocked_load(cfs_rq))
9923 		*done = false;
9924 
9925 	return decayed;
9926 }
9927 
9928 static unsigned long task_h_load(struct task_struct *p)
9929 {
9930 	return p->se.avg.load_avg;
9931 }
9932 #endif /* !CONFIG_FAIR_GROUP_SCHED */
9933 
9934 static void __sched_balance_update_blocked_averages(struct rq *rq)
9935 {
9936 	bool decayed = false, done = true;
9937 
9938 	update_blocked_load_tick(rq);
9939 
9940 	decayed |= __update_blocked_others(rq, &done);
9941 	decayed |= __update_blocked_fair(rq, &done);
9942 
9943 	update_has_blocked_load_status(rq, !done);
9944 	if (decayed)
9945 		cpufreq_update_util(rq, 0);
9946 }
9947 
9948 static void sched_balance_update_blocked_averages(int cpu)
9949 {
9950 	struct rq *rq = cpu_rq(cpu);
9951 
9952 	guard(rq_lock_irqsave)(rq);
9953 	update_rq_clock(rq);
9954 	__sched_balance_update_blocked_averages(rq);
9955 }
9956 
9957 /********** Helpers for sched_balance_find_src_group ************************/
9958 
9959 /*
9960  * sg_lb_stats - stats of a sched_group required for load-balancing:
9961  */
9962 struct sg_lb_stats {
9963 	unsigned long avg_load;			/* Avg load            over the CPUs of the group */
9964 	unsigned long group_load;		/* Total load          over the CPUs of the group */
9965 	unsigned long group_capacity;		/* Capacity            over the CPUs of the group */
9966 	unsigned long group_util;		/* Total utilization   over the CPUs of the group */
9967 	unsigned long group_runnable;		/* Total runnable time over the CPUs of the group */
9968 	unsigned int sum_nr_running;		/* Nr of all tasks running in the group */
9969 	unsigned int sum_h_nr_running;		/* Nr of CFS tasks running in the group */
9970 	unsigned int idle_cpus;                 /* Nr of idle CPUs         in the group */
9971 	unsigned int group_weight;
9972 	enum group_type group_type;
9973 	unsigned int group_asym_packing;	/* Tasks should be moved to preferred CPU */
9974 	unsigned int group_smt_balance;		/* Task on busy SMT be moved */
9975 	unsigned long group_misfit_task_load;	/* A CPU has a task too big for its capacity */
9976 #ifdef CONFIG_NUMA_BALANCING
9977 	unsigned int nr_numa_running;
9978 	unsigned int nr_preferred_running;
9979 #endif
9980 };
9981 
9982 /*
9983  * sd_lb_stats - stats of a sched_domain required for load-balancing:
9984  */
9985 struct sd_lb_stats {
9986 	struct sched_group *busiest;		/* Busiest group in this sd */
9987 	struct sched_group *local;		/* Local group in this sd */
9988 	unsigned long total_load;		/* Total load of all groups in sd */
9989 	unsigned long total_capacity;		/* Total capacity of all groups in sd */
9990 	unsigned long avg_load;			/* Average load across all groups in sd */
9991 	unsigned int prefer_sibling;		/* Tasks should go to sibling first */
9992 
9993 	struct sg_lb_stats busiest_stat;	/* Statistics of the busiest group */
9994 	struct sg_lb_stats local_stat;		/* Statistics of the local group */
9995 };
9996 
9997 static inline void init_sd_lb_stats(struct sd_lb_stats *sds)
9998 {
9999 	/*
10000 	 * Skimp on the clearing to avoid duplicate work. We can avoid clearing
10001 	 * local_stat because update_sg_lb_stats() does a full clear/assignment.
10002 	 * We must however set busiest_stat::group_type and
10003 	 * busiest_stat::idle_cpus to the worst busiest group because
10004 	 * update_sd_pick_busiest() reads these before assignment.
10005 	 */
10006 	*sds = (struct sd_lb_stats){
10007 		.busiest = NULL,
10008 		.local = NULL,
10009 		.total_load = 0UL,
10010 		.total_capacity = 0UL,
10011 		.busiest_stat = {
10012 			.idle_cpus = UINT_MAX,
10013 			.group_type = group_has_spare,
10014 		},
10015 	};
10016 }
10017 
10018 static unsigned long scale_rt_capacity(int cpu)
10019 {
10020 	unsigned long max = get_actual_cpu_capacity(cpu);
10021 	struct rq *rq = cpu_rq(cpu);
10022 	unsigned long used, free;
10023 	unsigned long irq;
10024 
10025 	irq = cpu_util_irq(rq);
10026 
10027 	if (unlikely(irq >= max))
10028 		return 1;
10029 
10030 	/*
10031 	 * avg_rt.util_avg and avg_dl.util_avg track binary signals
10032 	 * (running and not running) with weights 0 and 1024 respectively.
10033 	 */
10034 	used = cpu_util_rt(rq);
10035 	used += cpu_util_dl(rq);
10036 
10037 	if (unlikely(used >= max))
10038 		return 1;
10039 
10040 	free = max - used;
10041 
10042 	return scale_irq_capacity(free, irq, max);
10043 }
10044 
10045 static void update_cpu_capacity(struct sched_domain *sd, int cpu)
10046 {
10047 	unsigned long capacity = scale_rt_capacity(cpu);
10048 	struct sched_group *sdg = sd->groups;
10049 
10050 	if (!capacity)
10051 		capacity = 1;
10052 
10053 	cpu_rq(cpu)->cpu_capacity = capacity;
10054 	trace_sched_cpu_capacity_tp(cpu_rq(cpu));
10055 
10056 	sdg->sgc->capacity = capacity;
10057 	sdg->sgc->min_capacity = capacity;
10058 	sdg->sgc->max_capacity = capacity;
10059 }
10060 
10061 void update_group_capacity(struct sched_domain *sd, int cpu)
10062 {
10063 	struct sched_domain *child = sd->child;
10064 	struct sched_group *group, *sdg = sd->groups;
10065 	unsigned long capacity, min_capacity, max_capacity;
10066 	unsigned long interval;
10067 
10068 	interval = msecs_to_jiffies(sd->balance_interval);
10069 	interval = clamp(interval, 1UL, max_load_balance_interval);
10070 	sdg->sgc->next_update = jiffies + interval;
10071 
10072 	if (!child) {
10073 		update_cpu_capacity(sd, cpu);
10074 		return;
10075 	}
10076 
10077 	capacity = 0;
10078 	min_capacity = ULONG_MAX;
10079 	max_capacity = 0;
10080 
10081 	if (child->flags & SD_NUMA) {
10082 		/*
10083 		 * SD_NUMA domains cannot assume that child groups
10084 		 * span the current group.
10085 		 */
10086 
10087 		for_each_cpu(cpu, sched_group_span(sdg)) {
10088 			unsigned long cpu_cap = capacity_of(cpu);
10089 
10090 			capacity += cpu_cap;
10091 			min_capacity = min(cpu_cap, min_capacity);
10092 			max_capacity = max(cpu_cap, max_capacity);
10093 		}
10094 	} else  {
10095 		/*
10096 		 * !SD_NUMA domains can assume that child groups
10097 		 * span the current group.
10098 		 */
10099 
10100 		group = child->groups;
10101 		do {
10102 			struct sched_group_capacity *sgc = group->sgc;
10103 
10104 			capacity += sgc->capacity;
10105 			min_capacity = min(sgc->min_capacity, min_capacity);
10106 			max_capacity = max(sgc->max_capacity, max_capacity);
10107 			group = group->next;
10108 		} while (group != child->groups);
10109 	}
10110 
10111 	sdg->sgc->capacity = capacity;
10112 	sdg->sgc->min_capacity = min_capacity;
10113 	sdg->sgc->max_capacity = max_capacity;
10114 }
10115 
10116 /*
10117  * Check whether the capacity of the rq has been noticeably reduced by side
10118  * activity. The imbalance_pct is used for the threshold.
10119  * Return true is the capacity is reduced
10120  */
10121 static inline int
10122 check_cpu_capacity(struct rq *rq, struct sched_domain *sd)
10123 {
10124 	return ((rq->cpu_capacity * sd->imbalance_pct) <
10125 				(arch_scale_cpu_capacity(cpu_of(rq)) * 100));
10126 }
10127 
10128 /* Check if the rq has a misfit task */
10129 static inline bool check_misfit_status(struct rq *rq)
10130 {
10131 	return rq->misfit_task_load;
10132 }
10133 
10134 /*
10135  * Group imbalance indicates (and tries to solve) the problem where balancing
10136  * groups is inadequate due to ->cpus_ptr constraints.
10137  *
10138  * Imagine a situation of two groups of 4 CPUs each and 4 tasks each with a
10139  * cpumask covering 1 CPU of the first group and 3 CPUs of the second group.
10140  * Something like:
10141  *
10142  *	{ 0 1 2 3 } { 4 5 6 7 }
10143  *	        *     * * *
10144  *
10145  * If we were to balance group-wise we'd place two tasks in the first group and
10146  * two tasks in the second group. Clearly this is undesired as it will overload
10147  * cpu 3 and leave one of the CPUs in the second group unused.
10148  *
10149  * The current solution to this issue is detecting the skew in the first group
10150  * by noticing the lower domain failed to reach balance and had difficulty
10151  * moving tasks due to affinity constraints.
10152  *
10153  * When this is so detected; this group becomes a candidate for busiest; see
10154  * update_sd_pick_busiest(). And calculate_imbalance() and
10155  * sched_balance_find_src_group() avoid some of the usual balance conditions to allow it
10156  * to create an effective group imbalance.
10157  *
10158  * This is a somewhat tricky proposition since the next run might not find the
10159  * group imbalance and decide the groups need to be balanced again. A most
10160  * subtle and fragile situation.
10161  */
10162 
10163 static inline int sg_imbalanced(struct sched_group *group)
10164 {
10165 	return group->sgc->imbalance;
10166 }
10167 
10168 /*
10169  * group_has_capacity returns true if the group has spare capacity that could
10170  * be used by some tasks.
10171  * We consider that a group has spare capacity if the number of task is
10172  * smaller than the number of CPUs or if the utilization is lower than the
10173  * available capacity for CFS tasks.
10174  * For the latter, we use a threshold to stabilize the state, to take into
10175  * account the variance of the tasks' load and to return true if the available
10176  * capacity in meaningful for the load balancer.
10177  * As an example, an available capacity of 1% can appear but it doesn't make
10178  * any benefit for the load balance.
10179  */
10180 static inline bool
10181 group_has_capacity(unsigned int imbalance_pct, struct sg_lb_stats *sgs)
10182 {
10183 	if (sgs->sum_nr_running < sgs->group_weight)
10184 		return true;
10185 
10186 	if ((sgs->group_capacity * imbalance_pct) <
10187 			(sgs->group_runnable * 100))
10188 		return false;
10189 
10190 	if ((sgs->group_capacity * 100) >
10191 			(sgs->group_util * imbalance_pct))
10192 		return true;
10193 
10194 	return false;
10195 }
10196 
10197 /*
10198  *  group_is_overloaded returns true if the group has more tasks than it can
10199  *  handle.
10200  *  group_is_overloaded is not equals to !group_has_capacity because a group
10201  *  with the exact right number of tasks, has no more spare capacity but is not
10202  *  overloaded so both group_has_capacity and group_is_overloaded return
10203  *  false.
10204  */
10205 static inline bool
10206 group_is_overloaded(unsigned int imbalance_pct, struct sg_lb_stats *sgs)
10207 {
10208 	if (sgs->sum_nr_running <= sgs->group_weight)
10209 		return false;
10210 
10211 	if ((sgs->group_capacity * 100) <
10212 			(sgs->group_util * imbalance_pct))
10213 		return true;
10214 
10215 	if ((sgs->group_capacity * imbalance_pct) <
10216 			(sgs->group_runnable * 100))
10217 		return true;
10218 
10219 	return false;
10220 }
10221 
10222 static inline enum
10223 group_type group_classify(unsigned int imbalance_pct,
10224 			  struct sched_group *group,
10225 			  struct sg_lb_stats *sgs)
10226 {
10227 	if (group_is_overloaded(imbalance_pct, sgs))
10228 		return group_overloaded;
10229 
10230 	if (sg_imbalanced(group))
10231 		return group_imbalanced;
10232 
10233 	if (sgs->group_asym_packing)
10234 		return group_asym_packing;
10235 
10236 	if (sgs->group_smt_balance)
10237 		return group_smt_balance;
10238 
10239 	if (sgs->group_misfit_task_load)
10240 		return group_misfit_task;
10241 
10242 	if (!group_has_capacity(imbalance_pct, sgs))
10243 		return group_fully_busy;
10244 
10245 	return group_has_spare;
10246 }
10247 
10248 /**
10249  * sched_use_asym_prio - Check whether asym_packing priority must be used
10250  * @sd:		The scheduling domain of the load balancing
10251  * @cpu:	A CPU
10252  *
10253  * Always use CPU priority when balancing load between SMT siblings. When
10254  * balancing load between cores, it is not sufficient that @cpu is idle. Only
10255  * use CPU priority if the whole core is idle.
10256  *
10257  * Returns: True if the priority of @cpu must be followed. False otherwise.
10258  */
10259 static bool sched_use_asym_prio(struct sched_domain *sd, int cpu)
10260 {
10261 	if (!(sd->flags & SD_ASYM_PACKING))
10262 		return false;
10263 
10264 	if (!sched_smt_active())
10265 		return true;
10266 
10267 	return sd->flags & SD_SHARE_CPUCAPACITY || is_core_idle(cpu);
10268 }
10269 
10270 static inline bool sched_asym(struct sched_domain *sd, int dst_cpu, int src_cpu)
10271 {
10272 	/*
10273 	 * First check if @dst_cpu can do asym_packing load balance. Only do it
10274 	 * if it has higher priority than @src_cpu.
10275 	 */
10276 	return sched_use_asym_prio(sd, dst_cpu) &&
10277 		sched_asym_prefer(dst_cpu, src_cpu);
10278 }
10279 
10280 /**
10281  * sched_group_asym - Check if the destination CPU can do asym_packing balance
10282  * @env:	The load balancing environment
10283  * @sgs:	Load-balancing statistics of the candidate busiest group
10284  * @group:	The candidate busiest group
10285  *
10286  * @env::dst_cpu can do asym_packing if it has higher priority than the
10287  * preferred CPU of @group.
10288  *
10289  * Return: true if @env::dst_cpu can do with asym_packing load balance. False
10290  * otherwise.
10291  */
10292 static inline bool
10293 sched_group_asym(struct lb_env *env, struct sg_lb_stats *sgs, struct sched_group *group)
10294 {
10295 	/*
10296 	 * CPU priorities do not make sense for SMT cores with more than one
10297 	 * busy sibling.
10298 	 */
10299 	if ((group->flags & SD_SHARE_CPUCAPACITY) &&
10300 	    (sgs->group_weight - sgs->idle_cpus != 1))
10301 		return false;
10302 
10303 	return sched_asym(env->sd, env->dst_cpu, READ_ONCE(group->asym_prefer_cpu));
10304 }
10305 
10306 /* One group has more than one SMT CPU while the other group does not */
10307 static inline bool smt_vs_nonsmt_groups(struct sched_group *sg1,
10308 				    struct sched_group *sg2)
10309 {
10310 	if (!sg1 || !sg2)
10311 		return false;
10312 
10313 	return (sg1->flags & SD_SHARE_CPUCAPACITY) !=
10314 		(sg2->flags & SD_SHARE_CPUCAPACITY);
10315 }
10316 
10317 static inline bool smt_balance(struct lb_env *env, struct sg_lb_stats *sgs,
10318 			       struct sched_group *group)
10319 {
10320 	if (!env->idle)
10321 		return false;
10322 
10323 	/*
10324 	 * For SMT source group, it is better to move a task
10325 	 * to a CPU that doesn't have multiple tasks sharing its CPU capacity.
10326 	 * Note that if a group has a single SMT, SD_SHARE_CPUCAPACITY
10327 	 * will not be on.
10328 	 */
10329 	if (group->flags & SD_SHARE_CPUCAPACITY &&
10330 	    sgs->sum_h_nr_running > 1)
10331 		return true;
10332 
10333 	return false;
10334 }
10335 
10336 static inline long sibling_imbalance(struct lb_env *env,
10337 				    struct sd_lb_stats *sds,
10338 				    struct sg_lb_stats *busiest,
10339 				    struct sg_lb_stats *local)
10340 {
10341 	int ncores_busiest, ncores_local;
10342 	long imbalance;
10343 
10344 	if (!env->idle || !busiest->sum_nr_running)
10345 		return 0;
10346 
10347 	ncores_busiest = sds->busiest->cores;
10348 	ncores_local = sds->local->cores;
10349 
10350 	if (ncores_busiest == ncores_local) {
10351 		imbalance = busiest->sum_nr_running;
10352 		lsub_positive(&imbalance, local->sum_nr_running);
10353 		return imbalance;
10354 	}
10355 
10356 	/* Balance such that nr_running/ncores ratio are same on both groups */
10357 	imbalance = ncores_local * busiest->sum_nr_running;
10358 	lsub_positive(&imbalance, ncores_busiest * local->sum_nr_running);
10359 	/* Normalize imbalance and do rounding on normalization */
10360 	imbalance = 2 * imbalance + ncores_local + ncores_busiest;
10361 	imbalance /= ncores_local + ncores_busiest;
10362 
10363 	/* Take advantage of resource in an empty sched group */
10364 	if (imbalance <= 1 && local->sum_nr_running == 0 &&
10365 	    busiest->sum_nr_running > 1)
10366 		imbalance = 2;
10367 
10368 	return imbalance;
10369 }
10370 
10371 static inline bool
10372 sched_reduced_capacity(struct rq *rq, struct sched_domain *sd)
10373 {
10374 	/*
10375 	 * When there is more than 1 task, the group_overloaded case already
10376 	 * takes care of cpu with reduced capacity
10377 	 */
10378 	if (rq->cfs.h_nr_runnable != 1)
10379 		return false;
10380 
10381 	return check_cpu_capacity(rq, sd);
10382 }
10383 
10384 /**
10385  * update_sg_lb_stats - Update sched_group's statistics for load balancing.
10386  * @env: The load balancing environment.
10387  * @sds: Load-balancing data with statistics of the local group.
10388  * @group: sched_group whose statistics are to be updated.
10389  * @sgs: variable to hold the statistics for this group.
10390  * @sg_overloaded: sched_group is overloaded
10391  * @sg_overutilized: sched_group is overutilized
10392  */
10393 static inline void update_sg_lb_stats(struct lb_env *env,
10394 				      struct sd_lb_stats *sds,
10395 				      struct sched_group *group,
10396 				      struct sg_lb_stats *sgs,
10397 				      bool *sg_overloaded,
10398 				      bool *sg_overutilized)
10399 {
10400 	int i, nr_running, local_group, sd_flags = env->sd->flags;
10401 	bool balancing_at_rd = !env->sd->parent;
10402 
10403 	memset(sgs, 0, sizeof(*sgs));
10404 
10405 	local_group = group == sds->local;
10406 
10407 	for_each_cpu_and(i, sched_group_span(group), env->cpus) {
10408 		struct rq *rq = cpu_rq(i);
10409 		unsigned long load = cpu_load(rq);
10410 
10411 		sgs->group_load += load;
10412 		sgs->group_util += cpu_util_cfs(i);
10413 		sgs->group_runnable += cpu_runnable(rq);
10414 		sgs->sum_h_nr_running += rq->cfs.h_nr_runnable;
10415 
10416 		nr_running = rq->nr_running;
10417 		sgs->sum_nr_running += nr_running;
10418 
10419 		if (cpu_overutilized(i))
10420 			*sg_overutilized = 1;
10421 
10422 		/*
10423 		 * No need to call idle_cpu() if nr_running is not 0
10424 		 */
10425 		if (!nr_running && idle_cpu(i)) {
10426 			sgs->idle_cpus++;
10427 			/* Idle cpu can't have misfit task */
10428 			continue;
10429 		}
10430 
10431 		/* Overload indicator is only updated at root domain */
10432 		if (balancing_at_rd && nr_running > 1)
10433 			*sg_overloaded = 1;
10434 
10435 #ifdef CONFIG_NUMA_BALANCING
10436 		/* Only fbq_classify_group() uses this to classify NUMA groups */
10437 		if (sd_flags & SD_NUMA) {
10438 			sgs->nr_numa_running += rq->nr_numa_running;
10439 			sgs->nr_preferred_running += rq->nr_preferred_running;
10440 		}
10441 #endif
10442 		if (local_group)
10443 			continue;
10444 
10445 		if (sd_flags & SD_ASYM_CPUCAPACITY) {
10446 			/* Check for a misfit task on the cpu */
10447 			if (sgs->group_misfit_task_load < rq->misfit_task_load) {
10448 				sgs->group_misfit_task_load = rq->misfit_task_load;
10449 				*sg_overloaded = 1;
10450 			}
10451 		} else if (env->idle && sched_reduced_capacity(rq, env->sd)) {
10452 			/* Check for a task running on a CPU with reduced capacity */
10453 			if (sgs->group_misfit_task_load < load)
10454 				sgs->group_misfit_task_load = load;
10455 		}
10456 	}
10457 
10458 	sgs->group_capacity = group->sgc->capacity;
10459 
10460 	sgs->group_weight = group->group_weight;
10461 
10462 	/* Check if dst CPU is idle and preferred to this group */
10463 	if (!local_group && env->idle && sgs->sum_h_nr_running &&
10464 	    sched_group_asym(env, sgs, group))
10465 		sgs->group_asym_packing = 1;
10466 
10467 	/* Check for loaded SMT group to be balanced to dst CPU */
10468 	if (!local_group && smt_balance(env, sgs, group))
10469 		sgs->group_smt_balance = 1;
10470 
10471 	sgs->group_type = group_classify(env->sd->imbalance_pct, group, sgs);
10472 
10473 	/* Computing avg_load makes sense only when group is overloaded */
10474 	if (sgs->group_type == group_overloaded)
10475 		sgs->avg_load = (sgs->group_load * SCHED_CAPACITY_SCALE) /
10476 				sgs->group_capacity;
10477 }
10478 
10479 /**
10480  * update_sd_pick_busiest - return 1 on busiest group
10481  * @env: The load balancing environment.
10482  * @sds: sched_domain statistics
10483  * @sg: sched_group candidate to be checked for being the busiest
10484  * @sgs: sched_group statistics
10485  *
10486  * Determine if @sg is a busier group than the previously selected
10487  * busiest group.
10488  *
10489  * Return: %true if @sg is a busier group than the previously selected
10490  * busiest group. %false otherwise.
10491  */
10492 static bool update_sd_pick_busiest(struct lb_env *env,
10493 				   struct sd_lb_stats *sds,
10494 				   struct sched_group *sg,
10495 				   struct sg_lb_stats *sgs)
10496 {
10497 	struct sg_lb_stats *busiest = &sds->busiest_stat;
10498 
10499 	/* Make sure that there is at least one task to pull */
10500 	if (!sgs->sum_h_nr_running)
10501 		return false;
10502 
10503 	/*
10504 	 * Don't try to pull misfit tasks we can't help.
10505 	 * We can use max_capacity here as reduction in capacity on some
10506 	 * CPUs in the group should either be possible to resolve
10507 	 * internally or be covered by avg_load imbalance (eventually).
10508 	 */
10509 	if ((env->sd->flags & SD_ASYM_CPUCAPACITY) &&
10510 	    (sgs->group_type == group_misfit_task) &&
10511 	    (!capacity_greater(capacity_of(env->dst_cpu), sg->sgc->max_capacity) ||
10512 	     sds->local_stat.group_type != group_has_spare))
10513 		return false;
10514 
10515 	if (sgs->group_type > busiest->group_type)
10516 		return true;
10517 
10518 	if (sgs->group_type < busiest->group_type)
10519 		return false;
10520 
10521 	/*
10522 	 * The candidate and the current busiest group are the same type of
10523 	 * group. Let check which one is the busiest according to the type.
10524 	 */
10525 
10526 	switch (sgs->group_type) {
10527 	case group_overloaded:
10528 		/* Select the overloaded group with highest avg_load. */
10529 		return sgs->avg_load > busiest->avg_load;
10530 
10531 	case group_imbalanced:
10532 		/*
10533 		 * Select the 1st imbalanced group as we don't have any way to
10534 		 * choose one more than another.
10535 		 */
10536 		return false;
10537 
10538 	case group_asym_packing:
10539 		/* Prefer to move from lowest priority CPU's work */
10540 		return sched_asym_prefer(READ_ONCE(sds->busiest->asym_prefer_cpu),
10541 					 READ_ONCE(sg->asym_prefer_cpu));
10542 
10543 	case group_misfit_task:
10544 		/*
10545 		 * If we have more than one misfit sg go with the biggest
10546 		 * misfit.
10547 		 */
10548 		return sgs->group_misfit_task_load > busiest->group_misfit_task_load;
10549 
10550 	case group_smt_balance:
10551 		/*
10552 		 * Check if we have spare CPUs on either SMT group to
10553 		 * choose has spare or fully busy handling.
10554 		 */
10555 		if (sgs->idle_cpus != 0 || busiest->idle_cpus != 0)
10556 			goto has_spare;
10557 
10558 		fallthrough;
10559 
10560 	case group_fully_busy:
10561 		/*
10562 		 * Select the fully busy group with highest avg_load. In
10563 		 * theory, there is no need to pull task from such kind of
10564 		 * group because tasks have all compute capacity that they need
10565 		 * but we can still improve the overall throughput by reducing
10566 		 * contention when accessing shared HW resources.
10567 		 *
10568 		 * XXX for now avg_load is not computed and always 0 so we
10569 		 * select the 1st one, except if @sg is composed of SMT
10570 		 * siblings.
10571 		 */
10572 
10573 		if (sgs->avg_load < busiest->avg_load)
10574 			return false;
10575 
10576 		if (sgs->avg_load == busiest->avg_load) {
10577 			/*
10578 			 * SMT sched groups need more help than non-SMT groups.
10579 			 * If @sg happens to also be SMT, either choice is good.
10580 			 */
10581 			if (sds->busiest->flags & SD_SHARE_CPUCAPACITY)
10582 				return false;
10583 		}
10584 
10585 		break;
10586 
10587 	case group_has_spare:
10588 		/*
10589 		 * Do not pick sg with SMT CPUs over sg with pure CPUs,
10590 		 * as we do not want to pull task off SMT core with one task
10591 		 * and make the core idle.
10592 		 */
10593 		if (smt_vs_nonsmt_groups(sds->busiest, sg)) {
10594 			if (sg->flags & SD_SHARE_CPUCAPACITY && sgs->sum_h_nr_running <= 1)
10595 				return false;
10596 			else
10597 				return true;
10598 		}
10599 has_spare:
10600 
10601 		/*
10602 		 * Select not overloaded group with lowest number of idle CPUs
10603 		 * and highest number of running tasks. We could also compare
10604 		 * the spare capacity which is more stable but it can end up
10605 		 * that the group has less spare capacity but finally more idle
10606 		 * CPUs which means less opportunity to pull tasks.
10607 		 */
10608 		if (sgs->idle_cpus > busiest->idle_cpus)
10609 			return false;
10610 		else if ((sgs->idle_cpus == busiest->idle_cpus) &&
10611 			 (sgs->sum_nr_running <= busiest->sum_nr_running))
10612 			return false;
10613 
10614 		break;
10615 	}
10616 
10617 	/*
10618 	 * Candidate sg has no more than one task per CPU and has higher
10619 	 * per-CPU capacity. Migrating tasks to less capable CPUs may harm
10620 	 * throughput. Maximize throughput, power/energy consequences are not
10621 	 * considered.
10622 	 */
10623 	if ((env->sd->flags & SD_ASYM_CPUCAPACITY) &&
10624 	    (sgs->group_type <= group_fully_busy) &&
10625 	    (capacity_greater(sg->sgc->min_capacity, capacity_of(env->dst_cpu))))
10626 		return false;
10627 
10628 	return true;
10629 }
10630 
10631 #ifdef CONFIG_NUMA_BALANCING
10632 static inline enum fbq_type fbq_classify_group(struct sg_lb_stats *sgs)
10633 {
10634 	if (sgs->sum_h_nr_running > sgs->nr_numa_running)
10635 		return regular;
10636 	if (sgs->sum_h_nr_running > sgs->nr_preferred_running)
10637 		return remote;
10638 	return all;
10639 }
10640 
10641 static inline enum fbq_type fbq_classify_rq(struct rq *rq)
10642 {
10643 	if (rq->nr_running > rq->nr_numa_running)
10644 		return regular;
10645 	if (rq->nr_running > rq->nr_preferred_running)
10646 		return remote;
10647 	return all;
10648 }
10649 #else /* !CONFIG_NUMA_BALANCING: */
10650 static inline enum fbq_type fbq_classify_group(struct sg_lb_stats *sgs)
10651 {
10652 	return all;
10653 }
10654 
10655 static inline enum fbq_type fbq_classify_rq(struct rq *rq)
10656 {
10657 	return regular;
10658 }
10659 #endif /* !CONFIG_NUMA_BALANCING */
10660 
10661 
10662 struct sg_lb_stats;
10663 
10664 /*
10665  * task_running_on_cpu - return 1 if @p is running on @cpu.
10666  */
10667 
10668 static unsigned int task_running_on_cpu(int cpu, struct task_struct *p)
10669 {
10670 	/* Task has no contribution or is new */
10671 	if (cpu != task_cpu(p) || !READ_ONCE(p->se.avg.last_update_time))
10672 		return 0;
10673 
10674 	if (task_on_rq_queued(p))
10675 		return 1;
10676 
10677 	return 0;
10678 }
10679 
10680 /**
10681  * idle_cpu_without - would a given CPU be idle without p ?
10682  * @cpu: the processor on which idleness is tested.
10683  * @p: task which should be ignored.
10684  *
10685  * Return: 1 if the CPU would be idle. 0 otherwise.
10686  */
10687 static int idle_cpu_without(int cpu, struct task_struct *p)
10688 {
10689 	struct rq *rq = cpu_rq(cpu);
10690 
10691 	if (rq->curr != rq->idle && rq->curr != p)
10692 		return 0;
10693 
10694 	/*
10695 	 * rq->nr_running can't be used but an updated version without the
10696 	 * impact of p on cpu must be used instead. The updated nr_running
10697 	 * be computed and tested before calling idle_cpu_without().
10698 	 */
10699 
10700 	if (rq->ttwu_pending)
10701 		return 0;
10702 
10703 	return 1;
10704 }
10705 
10706 /*
10707  * update_sg_wakeup_stats - Update sched_group's statistics for wakeup.
10708  * @sd: The sched_domain level to look for idlest group.
10709  * @group: sched_group whose statistics are to be updated.
10710  * @sgs: variable to hold the statistics for this group.
10711  * @p: The task for which we look for the idlest group/CPU.
10712  */
10713 static inline void update_sg_wakeup_stats(struct sched_domain *sd,
10714 					  struct sched_group *group,
10715 					  struct sg_lb_stats *sgs,
10716 					  struct task_struct *p)
10717 {
10718 	int i, nr_running;
10719 
10720 	memset(sgs, 0, sizeof(*sgs));
10721 
10722 	/* Assume that task can't fit any CPU of the group */
10723 	if (sd->flags & SD_ASYM_CPUCAPACITY)
10724 		sgs->group_misfit_task_load = 1;
10725 
10726 	for_each_cpu_and(i, sched_group_span(group), p->cpus_ptr) {
10727 		struct rq *rq = cpu_rq(i);
10728 		unsigned int local;
10729 
10730 		sgs->group_load += cpu_load_without(rq, p);
10731 		sgs->group_util += cpu_util_without(i, p);
10732 		sgs->group_runnable += cpu_runnable_without(rq, p);
10733 		local = task_running_on_cpu(i, p);
10734 		sgs->sum_h_nr_running += rq->cfs.h_nr_runnable - local;
10735 
10736 		nr_running = rq->nr_running - local;
10737 		sgs->sum_nr_running += nr_running;
10738 
10739 		/*
10740 		 * No need to call idle_cpu_without() if nr_running is not 0
10741 		 */
10742 		if (!nr_running && idle_cpu_without(i, p))
10743 			sgs->idle_cpus++;
10744 
10745 		/* Check if task fits in the CPU */
10746 		if (sd->flags & SD_ASYM_CPUCAPACITY &&
10747 		    sgs->group_misfit_task_load &&
10748 		    task_fits_cpu(p, i))
10749 			sgs->group_misfit_task_load = 0;
10750 
10751 	}
10752 
10753 	sgs->group_capacity = group->sgc->capacity;
10754 
10755 	sgs->group_weight = group->group_weight;
10756 
10757 	sgs->group_type = group_classify(sd->imbalance_pct, group, sgs);
10758 
10759 	/*
10760 	 * Computing avg_load makes sense only when group is fully busy or
10761 	 * overloaded
10762 	 */
10763 	if (sgs->group_type == group_fully_busy ||
10764 		sgs->group_type == group_overloaded)
10765 		sgs->avg_load = (sgs->group_load * SCHED_CAPACITY_SCALE) /
10766 				sgs->group_capacity;
10767 }
10768 
10769 static bool update_pick_idlest(struct sched_group *idlest,
10770 			       struct sg_lb_stats *idlest_sgs,
10771 			       struct sched_group *group,
10772 			       struct sg_lb_stats *sgs)
10773 {
10774 	if (sgs->group_type < idlest_sgs->group_type)
10775 		return true;
10776 
10777 	if (sgs->group_type > idlest_sgs->group_type)
10778 		return false;
10779 
10780 	/*
10781 	 * The candidate and the current idlest group are the same type of
10782 	 * group. Let check which one is the idlest according to the type.
10783 	 */
10784 
10785 	switch (sgs->group_type) {
10786 	case group_overloaded:
10787 	case group_fully_busy:
10788 		/* Select the group with lowest avg_load. */
10789 		if (idlest_sgs->avg_load <= sgs->avg_load)
10790 			return false;
10791 		break;
10792 
10793 	case group_imbalanced:
10794 	case group_asym_packing:
10795 	case group_smt_balance:
10796 		/* Those types are not used in the slow wakeup path */
10797 		return false;
10798 
10799 	case group_misfit_task:
10800 		/* Select group with the highest max capacity */
10801 		if (idlest->sgc->max_capacity >= group->sgc->max_capacity)
10802 			return false;
10803 		break;
10804 
10805 	case group_has_spare:
10806 		/* Select group with most idle CPUs */
10807 		if (idlest_sgs->idle_cpus > sgs->idle_cpus)
10808 			return false;
10809 
10810 		/* Select group with lowest group_util */
10811 		if (idlest_sgs->idle_cpus == sgs->idle_cpus &&
10812 			idlest_sgs->group_util <= sgs->group_util)
10813 			return false;
10814 
10815 		break;
10816 	}
10817 
10818 	return true;
10819 }
10820 
10821 /*
10822  * sched_balance_find_dst_group() finds and returns the least busy CPU group within the
10823  * domain.
10824  *
10825  * Assumes p is allowed on at least one CPU in sd.
10826  */
10827 static struct sched_group *
10828 sched_balance_find_dst_group(struct sched_domain *sd, struct task_struct *p, int this_cpu)
10829 {
10830 	struct sched_group *idlest = NULL, *local = NULL, *group = sd->groups;
10831 	struct sg_lb_stats local_sgs, tmp_sgs;
10832 	struct sg_lb_stats *sgs;
10833 	unsigned long imbalance;
10834 	struct sg_lb_stats idlest_sgs = {
10835 			.avg_load = UINT_MAX,
10836 			.group_type = group_overloaded,
10837 	};
10838 
10839 	do {
10840 		int local_group;
10841 
10842 		/* Skip over this group if it has no CPUs allowed */
10843 		if (!cpumask_intersects(sched_group_span(group),
10844 					p->cpus_ptr))
10845 			continue;
10846 
10847 		/* Skip over this group if no cookie matched */
10848 		if (!sched_group_cookie_match(cpu_rq(this_cpu), p, group))
10849 			continue;
10850 
10851 		local_group = cpumask_test_cpu(this_cpu,
10852 					       sched_group_span(group));
10853 
10854 		if (local_group) {
10855 			sgs = &local_sgs;
10856 			local = group;
10857 		} else {
10858 			sgs = &tmp_sgs;
10859 		}
10860 
10861 		update_sg_wakeup_stats(sd, group, sgs, p);
10862 
10863 		if (!local_group && update_pick_idlest(idlest, &idlest_sgs, group, sgs)) {
10864 			idlest = group;
10865 			idlest_sgs = *sgs;
10866 		}
10867 
10868 	} while (group = group->next, group != sd->groups);
10869 
10870 
10871 	/* There is no idlest group to push tasks to */
10872 	if (!idlest)
10873 		return NULL;
10874 
10875 	/* The local group has been skipped because of CPU affinity */
10876 	if (!local)
10877 		return idlest;
10878 
10879 	/*
10880 	 * If the local group is idler than the selected idlest group
10881 	 * don't try and push the task.
10882 	 */
10883 	if (local_sgs.group_type < idlest_sgs.group_type)
10884 		return NULL;
10885 
10886 	/*
10887 	 * If the local group is busier than the selected idlest group
10888 	 * try and push the task.
10889 	 */
10890 	if (local_sgs.group_type > idlest_sgs.group_type)
10891 		return idlest;
10892 
10893 	switch (local_sgs.group_type) {
10894 	case group_overloaded:
10895 	case group_fully_busy:
10896 
10897 		/* Calculate allowed imbalance based on load */
10898 		imbalance = scale_load_down(NICE_0_LOAD) *
10899 				(sd->imbalance_pct-100) / 100;
10900 
10901 		/*
10902 		 * When comparing groups across NUMA domains, it's possible for
10903 		 * the local domain to be very lightly loaded relative to the
10904 		 * remote domains but "imbalance" skews the comparison making
10905 		 * remote CPUs look much more favourable. When considering
10906 		 * cross-domain, add imbalance to the load on the remote node
10907 		 * and consider staying local.
10908 		 */
10909 
10910 		if ((sd->flags & SD_NUMA) &&
10911 		    ((idlest_sgs.avg_load + imbalance) >= local_sgs.avg_load))
10912 			return NULL;
10913 
10914 		/*
10915 		 * If the local group is less loaded than the selected
10916 		 * idlest group don't try and push any tasks.
10917 		 */
10918 		if (idlest_sgs.avg_load >= (local_sgs.avg_load + imbalance))
10919 			return NULL;
10920 
10921 		if (100 * local_sgs.avg_load <= sd->imbalance_pct * idlest_sgs.avg_load)
10922 			return NULL;
10923 		break;
10924 
10925 	case group_imbalanced:
10926 	case group_asym_packing:
10927 	case group_smt_balance:
10928 		/* Those type are not used in the slow wakeup path */
10929 		return NULL;
10930 
10931 	case group_misfit_task:
10932 		/* Select group with the highest max capacity */
10933 		if (local->sgc->max_capacity >= idlest->sgc->max_capacity)
10934 			return NULL;
10935 		break;
10936 
10937 	case group_has_spare:
10938 #ifdef CONFIG_NUMA
10939 		if (sd->flags & SD_NUMA) {
10940 			int imb_numa_nr = sd->imb_numa_nr;
10941 #ifdef CONFIG_NUMA_BALANCING
10942 			int idlest_cpu;
10943 			/*
10944 			 * If there is spare capacity at NUMA, try to select
10945 			 * the preferred node
10946 			 */
10947 			if (cpu_to_node(this_cpu) == p->numa_preferred_nid)
10948 				return NULL;
10949 
10950 			idlest_cpu = cpumask_first(sched_group_span(idlest));
10951 			if (cpu_to_node(idlest_cpu) == p->numa_preferred_nid)
10952 				return idlest;
10953 #endif /* CONFIG_NUMA_BALANCING */
10954 			/*
10955 			 * Otherwise, keep the task close to the wakeup source
10956 			 * and improve locality if the number of running tasks
10957 			 * would remain below threshold where an imbalance is
10958 			 * allowed while accounting for the possibility the
10959 			 * task is pinned to a subset of CPUs. If there is a
10960 			 * real need of migration, periodic load balance will
10961 			 * take care of it.
10962 			 */
10963 			if (p->nr_cpus_allowed != NR_CPUS) {
10964 				unsigned int w = cpumask_weight_and(p->cpus_ptr,
10965 								sched_group_span(local));
10966 				imb_numa_nr = min(w, sd->imb_numa_nr);
10967 			}
10968 
10969 			imbalance = abs(local_sgs.idle_cpus - idlest_sgs.idle_cpus);
10970 			if (!adjust_numa_imbalance(imbalance,
10971 						   local_sgs.sum_nr_running + 1,
10972 						   imb_numa_nr)) {
10973 				return NULL;
10974 			}
10975 		}
10976 #endif /* CONFIG_NUMA */
10977 
10978 		/*
10979 		 * Select group with highest number of idle CPUs. We could also
10980 		 * compare the utilization which is more stable but it can end
10981 		 * up that the group has less spare capacity but finally more
10982 		 * idle CPUs which means more opportunity to run task.
10983 		 */
10984 		if (local_sgs.idle_cpus >= idlest_sgs.idle_cpus)
10985 			return NULL;
10986 		break;
10987 	}
10988 
10989 	return idlest;
10990 }
10991 
10992 static void update_idle_cpu_scan(struct lb_env *env,
10993 				 unsigned long sum_util)
10994 {
10995 	struct sched_domain_shared *sd_share;
10996 	int llc_weight, pct;
10997 	u64 x, y, tmp;
10998 	/*
10999 	 * Update the number of CPUs to scan in LLC domain, which could
11000 	 * be used as a hint in select_idle_cpu(). The update of sd_share
11001 	 * could be expensive because it is within a shared cache line.
11002 	 * So the write of this hint only occurs during periodic load
11003 	 * balancing, rather than CPU_NEWLY_IDLE, because the latter
11004 	 * can fire way more frequently than the former.
11005 	 */
11006 	if (!sched_feat(SIS_UTIL) || env->idle == CPU_NEWLY_IDLE)
11007 		return;
11008 
11009 	llc_weight = per_cpu(sd_llc_size, env->dst_cpu);
11010 	if (env->sd->span_weight != llc_weight)
11011 		return;
11012 
11013 	sd_share = rcu_dereference_all(per_cpu(sd_llc_shared, env->dst_cpu));
11014 	if (!sd_share)
11015 		return;
11016 
11017 	/*
11018 	 * The number of CPUs to search drops as sum_util increases, when
11019 	 * sum_util hits 85% or above, the scan stops.
11020 	 * The reason to choose 85% as the threshold is because this is the
11021 	 * imbalance_pct(117) when a LLC sched group is overloaded.
11022 	 *
11023 	 * let y = SCHED_CAPACITY_SCALE - p * x^2                       [1]
11024 	 * and y'= y / SCHED_CAPACITY_SCALE
11025 	 *
11026 	 * x is the ratio of sum_util compared to the CPU capacity:
11027 	 * x = sum_util / (llc_weight * SCHED_CAPACITY_SCALE)
11028 	 * y' is the ratio of CPUs to be scanned in the LLC domain,
11029 	 * and the number of CPUs to scan is calculated by:
11030 	 *
11031 	 * nr_scan = llc_weight * y'                                    [2]
11032 	 *
11033 	 * When x hits the threshold of overloaded, AKA, when
11034 	 * x = 100 / pct, y drops to 0. According to [1],
11035 	 * p should be SCHED_CAPACITY_SCALE * pct^2 / 10000
11036 	 *
11037 	 * Scale x by SCHED_CAPACITY_SCALE:
11038 	 * x' = sum_util / llc_weight;                                  [3]
11039 	 *
11040 	 * and finally [1] becomes:
11041 	 * y = SCHED_CAPACITY_SCALE -
11042 	 *     x'^2 * pct^2 / (10000 * SCHED_CAPACITY_SCALE)            [4]
11043 	 *
11044 	 */
11045 	/* equation [3] */
11046 	x = sum_util;
11047 	do_div(x, llc_weight);
11048 
11049 	/* equation [4] */
11050 	pct = env->sd->imbalance_pct;
11051 	tmp = x * x * pct * pct;
11052 	do_div(tmp, 10000 * SCHED_CAPACITY_SCALE);
11053 	tmp = min_t(long, tmp, SCHED_CAPACITY_SCALE);
11054 	y = SCHED_CAPACITY_SCALE - tmp;
11055 
11056 	/* equation [2] */
11057 	y *= llc_weight;
11058 	do_div(y, SCHED_CAPACITY_SCALE);
11059 	if ((int)y != sd_share->nr_idle_scan)
11060 		WRITE_ONCE(sd_share->nr_idle_scan, (int)y);
11061 }
11062 
11063 /**
11064  * update_sd_lb_stats - Update sched_domain's statistics for load balancing.
11065  * @env: The load balancing environment.
11066  * @sds: variable to hold the statistics for this sched_domain.
11067  */
11068 
11069 static inline void update_sd_lb_stats(struct lb_env *env, struct sd_lb_stats *sds)
11070 {
11071 	struct sched_group *sg = env->sd->groups;
11072 	struct sg_lb_stats *local = &sds->local_stat;
11073 	struct sg_lb_stats tmp_sgs;
11074 	unsigned long sum_util = 0;
11075 	bool sg_overloaded = 0, sg_overutilized = 0;
11076 
11077 	do {
11078 		struct sg_lb_stats *sgs = &tmp_sgs;
11079 		int local_group;
11080 
11081 		local_group = cpumask_test_cpu(env->dst_cpu, sched_group_span(sg));
11082 		if (local_group) {
11083 			sds->local = sg;
11084 			sgs = local;
11085 
11086 			if (env->idle != CPU_NEWLY_IDLE ||
11087 			    time_after_eq(jiffies, sg->sgc->next_update))
11088 				update_group_capacity(env->sd, env->dst_cpu);
11089 		}
11090 
11091 		update_sg_lb_stats(env, sds, sg, sgs, &sg_overloaded, &sg_overutilized);
11092 
11093 		if (!local_group && update_sd_pick_busiest(env, sds, sg, sgs)) {
11094 			sds->busiest = sg;
11095 			sds->busiest_stat = *sgs;
11096 		}
11097 
11098 		/* Now, start updating sd_lb_stats */
11099 		sds->total_load += sgs->group_load;
11100 		sds->total_capacity += sgs->group_capacity;
11101 
11102 		sum_util += sgs->group_util;
11103 		sg = sg->next;
11104 	} while (sg != env->sd->groups);
11105 
11106 	/*
11107 	 * Indicate that the child domain of the busiest group prefers tasks
11108 	 * go to a child's sibling domains first. NB the flags of a sched group
11109 	 * are those of the child domain.
11110 	 */
11111 	if (sds->busiest)
11112 		sds->prefer_sibling = !!(sds->busiest->flags & SD_PREFER_SIBLING);
11113 
11114 
11115 	if (env->sd->flags & SD_NUMA)
11116 		env->fbq_type = fbq_classify_group(&sds->busiest_stat);
11117 
11118 	if (!env->sd->parent) {
11119 		/* update overload indicator if we are at root domain */
11120 		set_rd_overloaded(env->dst_rq->rd, sg_overloaded);
11121 
11122 		/* Update over-utilization (tipping point, U >= 0) indicator */
11123 		set_rd_overutilized(env->dst_rq->rd, sg_overutilized);
11124 	} else if (sg_overutilized) {
11125 		set_rd_overutilized(env->dst_rq->rd, sg_overutilized);
11126 	}
11127 
11128 	update_idle_cpu_scan(env, sum_util);
11129 }
11130 
11131 /**
11132  * calculate_imbalance - Calculate the amount of imbalance present within the
11133  *			 groups of a given sched_domain during load balance.
11134  * @env: load balance environment
11135  * @sds: statistics of the sched_domain whose imbalance is to be calculated.
11136  */
11137 static inline void calculate_imbalance(struct lb_env *env, struct sd_lb_stats *sds)
11138 {
11139 	struct sg_lb_stats *local, *busiest;
11140 
11141 	local = &sds->local_stat;
11142 	busiest = &sds->busiest_stat;
11143 
11144 	if (busiest->group_type == group_misfit_task) {
11145 		if (env->sd->flags & SD_ASYM_CPUCAPACITY) {
11146 			/* Set imbalance to allow misfit tasks to be balanced. */
11147 			env->migration_type = migrate_misfit;
11148 			env->imbalance = 1;
11149 		} else {
11150 			/*
11151 			 * Set load imbalance to allow moving task from cpu
11152 			 * with reduced capacity.
11153 			 */
11154 			env->migration_type = migrate_load;
11155 			env->imbalance = busiest->group_misfit_task_load;
11156 		}
11157 		return;
11158 	}
11159 
11160 	if (busiest->group_type == group_asym_packing) {
11161 		/*
11162 		 * In case of asym capacity, we will try to migrate all load to
11163 		 * the preferred CPU.
11164 		 */
11165 		env->migration_type = migrate_task;
11166 		env->imbalance = busiest->sum_h_nr_running;
11167 		return;
11168 	}
11169 
11170 	if (busiest->group_type == group_smt_balance) {
11171 		/* Reduce number of tasks sharing CPU capacity */
11172 		env->migration_type = migrate_task;
11173 		env->imbalance = 1;
11174 		return;
11175 	}
11176 
11177 	if (busiest->group_type == group_imbalanced) {
11178 		/*
11179 		 * In the group_imb case we cannot rely on group-wide averages
11180 		 * to ensure CPU-load equilibrium, try to move any task to fix
11181 		 * the imbalance. The next load balance will take care of
11182 		 * balancing back the system.
11183 		 */
11184 		env->migration_type = migrate_task;
11185 		env->imbalance = 1;
11186 		return;
11187 	}
11188 
11189 	/*
11190 	 * Try to use spare capacity of local group without overloading it or
11191 	 * emptying busiest.
11192 	 */
11193 	if (local->group_type == group_has_spare) {
11194 		if ((busiest->group_type > group_fully_busy) &&
11195 		    !(env->sd->flags & SD_SHARE_LLC)) {
11196 			/*
11197 			 * If busiest is overloaded, try to fill spare
11198 			 * capacity. This might end up creating spare capacity
11199 			 * in busiest or busiest still being overloaded but
11200 			 * there is no simple way to directly compute the
11201 			 * amount of load to migrate in order to balance the
11202 			 * system.
11203 			 */
11204 			env->migration_type = migrate_util;
11205 			env->imbalance = max(local->group_capacity, local->group_util) -
11206 					 local->group_util;
11207 
11208 			/*
11209 			 * In some cases, the group's utilization is max or even
11210 			 * higher than capacity because of migrations but the
11211 			 * local CPU is (newly) idle. There is at least one
11212 			 * waiting task in this overloaded busiest group. Let's
11213 			 * try to pull it.
11214 			 */
11215 			if (env->idle && env->imbalance == 0) {
11216 				env->migration_type = migrate_task;
11217 				env->imbalance = 1;
11218 			}
11219 
11220 			return;
11221 		}
11222 
11223 		if (busiest->group_weight == 1 || sds->prefer_sibling) {
11224 			/*
11225 			 * When prefer sibling, evenly spread running tasks on
11226 			 * groups.
11227 			 */
11228 			env->migration_type = migrate_task;
11229 			env->imbalance = sibling_imbalance(env, sds, busiest, local);
11230 		} else {
11231 
11232 			/*
11233 			 * If there is no overload, we just want to even the number of
11234 			 * idle CPUs.
11235 			 */
11236 			env->migration_type = migrate_task;
11237 			env->imbalance = max_t(long, 0,
11238 					       (local->idle_cpus - busiest->idle_cpus));
11239 		}
11240 
11241 #ifdef CONFIG_NUMA
11242 		/* Consider allowing a small imbalance between NUMA groups */
11243 		if (env->sd->flags & SD_NUMA) {
11244 			env->imbalance = adjust_numa_imbalance(env->imbalance,
11245 							       local->sum_nr_running + 1,
11246 							       env->sd->imb_numa_nr);
11247 		}
11248 #endif
11249 
11250 		/* Number of tasks to move to restore balance */
11251 		env->imbalance >>= 1;
11252 
11253 		return;
11254 	}
11255 
11256 	/*
11257 	 * Local is fully busy but has to take more load to relieve the
11258 	 * busiest group
11259 	 */
11260 	if (local->group_type < group_overloaded) {
11261 		/*
11262 		 * Local will become overloaded so the avg_load metrics are
11263 		 * finally needed.
11264 		 */
11265 
11266 		local->avg_load = (local->group_load * SCHED_CAPACITY_SCALE) /
11267 				  local->group_capacity;
11268 
11269 		/*
11270 		 * If the local group is more loaded than the selected
11271 		 * busiest group don't try to pull any tasks.
11272 		 */
11273 		if (local->avg_load >= busiest->avg_load) {
11274 			env->imbalance = 0;
11275 			return;
11276 		}
11277 
11278 		sds->avg_load = (sds->total_load * SCHED_CAPACITY_SCALE) /
11279 				sds->total_capacity;
11280 
11281 		/*
11282 		 * If the local group is more loaded than the average system
11283 		 * load, don't try to pull any tasks.
11284 		 */
11285 		if (local->avg_load >= sds->avg_load) {
11286 			env->imbalance = 0;
11287 			return;
11288 		}
11289 
11290 	}
11291 
11292 	/*
11293 	 * Both group are or will become overloaded and we're trying to get all
11294 	 * the CPUs to the average_load, so we don't want to push ourselves
11295 	 * above the average load, nor do we wish to reduce the max loaded CPU
11296 	 * below the average load. At the same time, we also don't want to
11297 	 * reduce the group load below the group capacity. Thus we look for
11298 	 * the minimum possible imbalance.
11299 	 */
11300 	env->migration_type = migrate_load;
11301 	env->imbalance = min(
11302 		(busiest->avg_load - sds->avg_load) * busiest->group_capacity,
11303 		(sds->avg_load - local->avg_load) * local->group_capacity
11304 	) / SCHED_CAPACITY_SCALE;
11305 }
11306 
11307 /******* sched_balance_find_src_group() helpers end here *********************/
11308 
11309 /*
11310  * Decision matrix according to the local and busiest group type:
11311  *
11312  * busiest \ local has_spare fully_busy misfit asym imbalanced overloaded
11313  * has_spare        nr_idle   balanced   N/A    N/A  balanced   balanced
11314  * fully_busy       nr_idle   nr_idle    N/A    N/A  balanced   balanced
11315  * misfit_task      force     N/A        N/A    N/A  N/A        N/A
11316  * asym_packing     force     force      N/A    N/A  force      force
11317  * imbalanced       force     force      N/A    N/A  force      force
11318  * overloaded       force     force      N/A    N/A  force      avg_load
11319  *
11320  * N/A :      Not Applicable because already filtered while updating
11321  *            statistics.
11322  * balanced : The system is balanced for these 2 groups.
11323  * force :    Calculate the imbalance as load migration is probably needed.
11324  * avg_load : Only if imbalance is significant enough.
11325  * nr_idle :  dst_cpu is not busy and the number of idle CPUs is quite
11326  *            different in groups.
11327  */
11328 
11329 /**
11330  * sched_balance_find_src_group - Returns the busiest group within the sched_domain
11331  * if there is an imbalance.
11332  * @env: The load balancing environment.
11333  *
11334  * Also calculates the amount of runnable load which should be moved
11335  * to restore balance.
11336  *
11337  * Return:	- The busiest group if imbalance exists.
11338  */
11339 static struct sched_group *sched_balance_find_src_group(struct lb_env *env)
11340 {
11341 	struct sg_lb_stats *local, *busiest;
11342 	struct sd_lb_stats sds;
11343 
11344 	init_sd_lb_stats(&sds);
11345 
11346 	/*
11347 	 * Compute the various statistics relevant for load balancing at
11348 	 * this level.
11349 	 */
11350 	update_sd_lb_stats(env, &sds);
11351 
11352 	/* There is no busy sibling group to pull tasks from */
11353 	if (!sds.busiest)
11354 		goto out_balanced;
11355 
11356 	busiest = &sds.busiest_stat;
11357 
11358 	/* Misfit tasks should be dealt with regardless of the avg load */
11359 	if (busiest->group_type == group_misfit_task)
11360 		goto force_balance;
11361 
11362 	if (!is_rd_overutilized(env->dst_rq->rd) &&
11363 	    rcu_dereference_all(env->dst_rq->rd->pd))
11364 		goto out_balanced;
11365 
11366 	/* ASYM feature bypasses nice load balance check */
11367 	if (busiest->group_type == group_asym_packing)
11368 		goto force_balance;
11369 
11370 	/*
11371 	 * If the busiest group is imbalanced the below checks don't
11372 	 * work because they assume all things are equal, which typically
11373 	 * isn't true due to cpus_ptr constraints and the like.
11374 	 */
11375 	if (busiest->group_type == group_imbalanced)
11376 		goto force_balance;
11377 
11378 	local = &sds.local_stat;
11379 	/*
11380 	 * If the local group is busier than the selected busiest group
11381 	 * don't try and pull any tasks.
11382 	 */
11383 	if (local->group_type > busiest->group_type)
11384 		goto out_balanced;
11385 
11386 	/*
11387 	 * When groups are overloaded, use the avg_load to ensure fairness
11388 	 * between tasks.
11389 	 */
11390 	if (local->group_type == group_overloaded) {
11391 		/*
11392 		 * If the local group is more loaded than the selected
11393 		 * busiest group don't try to pull any tasks.
11394 		 */
11395 		if (local->avg_load >= busiest->avg_load)
11396 			goto out_balanced;
11397 
11398 		/* XXX broken for overlapping NUMA groups */
11399 		sds.avg_load = (sds.total_load * SCHED_CAPACITY_SCALE) /
11400 				sds.total_capacity;
11401 
11402 		/*
11403 		 * Don't pull any tasks if this group is already above the
11404 		 * domain average load.
11405 		 */
11406 		if (local->avg_load >= sds.avg_load)
11407 			goto out_balanced;
11408 
11409 		/*
11410 		 * If the busiest group is more loaded, use imbalance_pct to be
11411 		 * conservative.
11412 		 */
11413 		if (100 * busiest->avg_load <=
11414 				env->sd->imbalance_pct * local->avg_load)
11415 			goto out_balanced;
11416 	}
11417 
11418 	/*
11419 	 * Try to move all excess tasks to a sibling domain of the busiest
11420 	 * group's child domain.
11421 	 */
11422 	if (sds.prefer_sibling && local->group_type == group_has_spare &&
11423 	    sibling_imbalance(env, &sds, busiest, local) > 1)
11424 		goto force_balance;
11425 
11426 	if (busiest->group_type != group_overloaded) {
11427 		if (!env->idle) {
11428 			/*
11429 			 * If the busiest group is not overloaded (and as a
11430 			 * result the local one too) but this CPU is already
11431 			 * busy, let another idle CPU try to pull task.
11432 			 */
11433 			goto out_balanced;
11434 		}
11435 
11436 		if (busiest->group_type == group_smt_balance &&
11437 		    smt_vs_nonsmt_groups(sds.local, sds.busiest)) {
11438 			/* Let non SMT CPU pull from SMT CPU sharing with sibling */
11439 			goto force_balance;
11440 		}
11441 
11442 		if (busiest->group_weight > 1 &&
11443 		    local->idle_cpus <= (busiest->idle_cpus + 1)) {
11444 			/*
11445 			 * If the busiest group is not overloaded
11446 			 * and there is no imbalance between this and busiest
11447 			 * group wrt idle CPUs, it is balanced. The imbalance
11448 			 * becomes significant if the diff is greater than 1
11449 			 * otherwise we might end up to just move the imbalance
11450 			 * on another group. Of course this applies only if
11451 			 * there is more than 1 CPU per group.
11452 			 */
11453 			goto out_balanced;
11454 		}
11455 
11456 		if (busiest->sum_h_nr_running == 1) {
11457 			/*
11458 			 * busiest doesn't have any tasks waiting to run
11459 			 */
11460 			goto out_balanced;
11461 		}
11462 	}
11463 
11464 force_balance:
11465 	/* Looks like there is an imbalance. Compute it */
11466 	calculate_imbalance(env, &sds);
11467 	return env->imbalance ? sds.busiest : NULL;
11468 
11469 out_balanced:
11470 	env->imbalance = 0;
11471 	return NULL;
11472 }
11473 
11474 /*
11475  * sched_balance_find_src_rq - find the busiest runqueue among the CPUs in the group.
11476  */
11477 static struct rq *sched_balance_find_src_rq(struct lb_env *env,
11478 				     struct sched_group *group)
11479 {
11480 	struct rq *busiest = NULL, *rq;
11481 	unsigned long busiest_util = 0, busiest_load = 0, busiest_capacity = 1;
11482 	unsigned int busiest_nr = 0;
11483 	int i;
11484 
11485 	for_each_cpu_and(i, sched_group_span(group), env->cpus) {
11486 		unsigned long capacity, load, util;
11487 		unsigned int nr_running;
11488 		enum fbq_type rt;
11489 
11490 		rq = cpu_rq(i);
11491 		rt = fbq_classify_rq(rq);
11492 
11493 		/*
11494 		 * We classify groups/runqueues into three groups:
11495 		 *  - regular: there are !numa tasks
11496 		 *  - remote:  there are numa tasks that run on the 'wrong' node
11497 		 *  - all:     there is no distinction
11498 		 *
11499 		 * In order to avoid migrating ideally placed numa tasks,
11500 		 * ignore those when there's better options.
11501 		 *
11502 		 * If we ignore the actual busiest queue to migrate another
11503 		 * task, the next balance pass can still reduce the busiest
11504 		 * queue by moving tasks around inside the node.
11505 		 *
11506 		 * If we cannot move enough load due to this classification
11507 		 * the next pass will adjust the group classification and
11508 		 * allow migration of more tasks.
11509 		 *
11510 		 * Both cases only affect the total convergence complexity.
11511 		 */
11512 		if (rt > env->fbq_type)
11513 			continue;
11514 
11515 		nr_running = rq->cfs.h_nr_runnable;
11516 		if (!nr_running)
11517 			continue;
11518 
11519 		capacity = capacity_of(i);
11520 
11521 		/*
11522 		 * For ASYM_CPUCAPACITY domains, don't pick a CPU that could
11523 		 * eventually lead to active_balancing high->low capacity.
11524 		 * Higher per-CPU capacity is considered better than balancing
11525 		 * average load.
11526 		 */
11527 		if (env->sd->flags & SD_ASYM_CPUCAPACITY &&
11528 		    !capacity_greater(capacity_of(env->dst_cpu), capacity) &&
11529 		    nr_running == 1)
11530 			continue;
11531 
11532 		/*
11533 		 * Make sure we only pull tasks from a CPU of lower priority
11534 		 * when balancing between SMT siblings.
11535 		 *
11536 		 * If balancing between cores, let lower priority CPUs help
11537 		 * SMT cores with more than one busy sibling.
11538 		 */
11539 		if (sched_asym(env->sd, i, env->dst_cpu) && nr_running == 1)
11540 			continue;
11541 
11542 		switch (env->migration_type) {
11543 		case migrate_load:
11544 			/*
11545 			 * When comparing with load imbalance, use cpu_load()
11546 			 * which is not scaled with the CPU capacity.
11547 			 */
11548 			load = cpu_load(rq);
11549 
11550 			if (nr_running == 1 && load > env->imbalance &&
11551 			    !check_cpu_capacity(rq, env->sd))
11552 				break;
11553 
11554 			/*
11555 			 * For the load comparisons with the other CPUs,
11556 			 * consider the cpu_load() scaled with the CPU
11557 			 * capacity, so that the load can be moved away
11558 			 * from the CPU that is potentially running at a
11559 			 * lower capacity.
11560 			 *
11561 			 * Thus we're looking for max(load_i / capacity_i),
11562 			 * crosswise multiplication to rid ourselves of the
11563 			 * division works out to:
11564 			 * load_i * capacity_j > load_j * capacity_i;
11565 			 * where j is our previous maximum.
11566 			 */
11567 			if (load * busiest_capacity > busiest_load * capacity) {
11568 				busiest_load = load;
11569 				busiest_capacity = capacity;
11570 				busiest = rq;
11571 			}
11572 			break;
11573 
11574 		case migrate_util:
11575 			util = cpu_util_cfs_boost(i);
11576 
11577 			/*
11578 			 * Don't try to pull utilization from a CPU with one
11579 			 * running task. Whatever its utilization, we will fail
11580 			 * detach the task.
11581 			 */
11582 			if (nr_running <= 1)
11583 				continue;
11584 
11585 			if (busiest_util < util) {
11586 				busiest_util = util;
11587 				busiest = rq;
11588 			}
11589 			break;
11590 
11591 		case migrate_task:
11592 			if (busiest_nr < nr_running) {
11593 				busiest_nr = nr_running;
11594 				busiest = rq;
11595 			}
11596 			break;
11597 
11598 		case migrate_misfit:
11599 			/*
11600 			 * For ASYM_CPUCAPACITY domains with misfit tasks we
11601 			 * simply seek the "biggest" misfit task.
11602 			 */
11603 			if (rq->misfit_task_load > busiest_load) {
11604 				busiest_load = rq->misfit_task_load;
11605 				busiest = rq;
11606 			}
11607 
11608 			break;
11609 
11610 		}
11611 	}
11612 
11613 	return busiest;
11614 }
11615 
11616 /*
11617  * Max backoff if we encounter pinned tasks. Pretty arbitrary value, but
11618  * so long as it is large enough.
11619  */
11620 #define MAX_PINNED_INTERVAL	512
11621 
11622 static inline bool
11623 asym_active_balance(struct lb_env *env)
11624 {
11625 	/*
11626 	 * ASYM_PACKING needs to force migrate tasks from busy but lower
11627 	 * priority CPUs in order to pack all tasks in the highest priority
11628 	 * CPUs. When done between cores, do it only if the whole core if the
11629 	 * whole core is idle.
11630 	 *
11631 	 * If @env::src_cpu is an SMT core with busy siblings, let
11632 	 * the lower priority @env::dst_cpu help it. Do not follow
11633 	 * CPU priority.
11634 	 */
11635 	return env->idle && sched_use_asym_prio(env->sd, env->dst_cpu) &&
11636 	       (sched_asym_prefer(env->dst_cpu, env->src_cpu) ||
11637 		!sched_use_asym_prio(env->sd, env->src_cpu));
11638 }
11639 
11640 static inline bool
11641 imbalanced_active_balance(struct lb_env *env)
11642 {
11643 	struct sched_domain *sd = env->sd;
11644 
11645 	/*
11646 	 * The imbalanced case includes the case of pinned tasks preventing a fair
11647 	 * distribution of the load on the system but also the even distribution of the
11648 	 * threads on a system with spare capacity
11649 	 */
11650 	if ((env->migration_type == migrate_task) &&
11651 	    (sd->nr_balance_failed > sd->cache_nice_tries+2))
11652 		return 1;
11653 
11654 	return 0;
11655 }
11656 
11657 static int need_active_balance(struct lb_env *env)
11658 {
11659 	struct sched_domain *sd = env->sd;
11660 
11661 	if (asym_active_balance(env))
11662 		return 1;
11663 
11664 	if (imbalanced_active_balance(env))
11665 		return 1;
11666 
11667 	/*
11668 	 * The dst_cpu is idle and the src_cpu CPU has only 1 CFS task.
11669 	 * It's worth migrating the task if the src_cpu's capacity is reduced
11670 	 * because of other sched_class or IRQs if more capacity stays
11671 	 * available on dst_cpu.
11672 	 */
11673 	if (env->idle &&
11674 	    (env->src_rq->cfs.h_nr_runnable == 1)) {
11675 		if ((check_cpu_capacity(env->src_rq, sd)) &&
11676 		    (capacity_of(env->src_cpu)*sd->imbalance_pct < capacity_of(env->dst_cpu)*100))
11677 			return 1;
11678 	}
11679 
11680 	if (env->migration_type == migrate_misfit)
11681 		return 1;
11682 
11683 	return 0;
11684 }
11685 
11686 static int active_load_balance_cpu_stop(void *data);
11687 
11688 static int should_we_balance(struct lb_env *env)
11689 {
11690 	struct cpumask *swb_cpus = this_cpu_cpumask_var_ptr(should_we_balance_tmpmask);
11691 	struct sched_group *sg = env->sd->groups;
11692 	int cpu, idle_smt = -1;
11693 
11694 	/*
11695 	 * Ensure the balancing environment is consistent; can happen
11696 	 * when the softirq triggers 'during' hotplug.
11697 	 */
11698 	if (!cpumask_test_cpu(env->dst_cpu, env->cpus))
11699 		return 0;
11700 
11701 	/*
11702 	 * In the newly idle case, we will allow all the CPUs
11703 	 * to do the newly idle load balance.
11704 	 *
11705 	 * However, we bail out if we already have tasks or a wakeup pending,
11706 	 * to optimize wakeup latency.
11707 	 */
11708 	if (env->idle == CPU_NEWLY_IDLE) {
11709 		if (env->dst_rq->nr_running > 0 || env->dst_rq->ttwu_pending)
11710 			return 0;
11711 		return 1;
11712 	}
11713 
11714 	cpumask_copy(swb_cpus, group_balance_mask(sg));
11715 	/* Try to find first idle CPU */
11716 	for_each_cpu_and(cpu, swb_cpus, env->cpus) {
11717 		if (!idle_cpu(cpu))
11718 			continue;
11719 
11720 		/*
11721 		 * Don't balance to idle SMT in busy core right away when
11722 		 * balancing cores, but remember the first idle SMT CPU for
11723 		 * later consideration.  Find CPU on an idle core first.
11724 		 */
11725 		if (!(env->sd->flags & SD_SHARE_CPUCAPACITY) && !is_core_idle(cpu)) {
11726 			if (idle_smt == -1)
11727 				idle_smt = cpu;
11728 			/*
11729 			 * If the core is not idle, and first SMT sibling which is
11730 			 * idle has been found, then its not needed to check other
11731 			 * SMT siblings for idleness:
11732 			 */
11733 #ifdef CONFIG_SCHED_SMT
11734 			cpumask_andnot(swb_cpus, swb_cpus, cpu_smt_mask(cpu));
11735 #endif
11736 			continue;
11737 		}
11738 
11739 		/*
11740 		 * Are we the first idle core in a non-SMT domain or higher,
11741 		 * or the first idle CPU in a SMT domain?
11742 		 */
11743 		return cpu == env->dst_cpu;
11744 	}
11745 
11746 	/* Are we the first idle CPU with busy siblings? */
11747 	if (idle_smt != -1)
11748 		return idle_smt == env->dst_cpu;
11749 
11750 	/* Are we the first CPU of this group ? */
11751 	return group_balance_cpu(sg) == env->dst_cpu;
11752 }
11753 
11754 static void update_lb_imbalance_stat(struct lb_env *env, struct sched_domain *sd,
11755 				     enum cpu_idle_type idle)
11756 {
11757 	if (!schedstat_enabled())
11758 		return;
11759 
11760 	switch (env->migration_type) {
11761 	case migrate_load:
11762 		__schedstat_add(sd->lb_imbalance_load[idle], env->imbalance);
11763 		break;
11764 	case migrate_util:
11765 		__schedstat_add(sd->lb_imbalance_util[idle], env->imbalance);
11766 		break;
11767 	case migrate_task:
11768 		__schedstat_add(sd->lb_imbalance_task[idle], env->imbalance);
11769 		break;
11770 	case migrate_misfit:
11771 		__schedstat_add(sd->lb_imbalance_misfit[idle], env->imbalance);
11772 		break;
11773 	}
11774 }
11775 
11776 /*
11777  * This flag serializes load-balancing passes over large domains
11778  * (above the NODE topology level) - only one load-balancing instance
11779  * may run at a time, to reduce overhead on very large systems with
11780  * lots of CPUs and large NUMA distances.
11781  *
11782  * - Note that load-balancing passes triggered while another one
11783  *   is executing are skipped and not re-tried.
11784  *
11785  * - Also note that this does not serialize rebalance_domains()
11786  *   execution, as non-SD_SERIALIZE domains will still be
11787  *   load-balanced in parallel.
11788  */
11789 static atomic_t sched_balance_running = ATOMIC_INIT(0);
11790 
11791 /*
11792  * Check this_cpu to ensure it is balanced within domain. Attempt to move
11793  * tasks if there is an imbalance.
11794  */
11795 static int sched_balance_rq(int this_cpu, struct rq *this_rq,
11796 			struct sched_domain *sd, enum cpu_idle_type idle,
11797 			int *continue_balancing)
11798 {
11799 	int ld_moved, cur_ld_moved, active_balance = 0;
11800 	struct sched_domain *sd_parent = sd->parent;
11801 	struct sched_group *group;
11802 	struct rq *busiest;
11803 	struct rq_flags rf;
11804 	struct cpumask *cpus = this_cpu_cpumask_var_ptr(load_balance_mask);
11805 	struct lb_env env = {
11806 		.sd		= sd,
11807 		.dst_cpu	= this_cpu,
11808 		.dst_rq		= this_rq,
11809 		.dst_grpmask    = group_balance_mask(sd->groups),
11810 		.idle		= idle,
11811 		.loop_break	= SCHED_NR_MIGRATE_BREAK,
11812 		.cpus		= cpus,
11813 		.fbq_type	= all,
11814 		.tasks		= LIST_HEAD_INIT(env.tasks),
11815 	};
11816 	bool need_unlock = false;
11817 
11818 	cpumask_and(cpus, sched_domain_span(sd), cpu_active_mask);
11819 
11820 	schedstat_inc(sd->lb_count[idle]);
11821 
11822 redo:
11823 	if (!should_we_balance(&env)) {
11824 		*continue_balancing = 0;
11825 		goto out_balanced;
11826 	}
11827 
11828 	if (!need_unlock && (sd->flags & SD_SERIALIZE)) {
11829 		int zero = 0;
11830 		if (!atomic_try_cmpxchg_acquire(&sched_balance_running, &zero, 1))
11831 			goto out_balanced;
11832 
11833 		need_unlock = true;
11834 	}
11835 
11836 	group = sched_balance_find_src_group(&env);
11837 	if (!group) {
11838 		schedstat_inc(sd->lb_nobusyg[idle]);
11839 		goto out_balanced;
11840 	}
11841 
11842 	busiest = sched_balance_find_src_rq(&env, group);
11843 	if (!busiest) {
11844 		schedstat_inc(sd->lb_nobusyq[idle]);
11845 		goto out_balanced;
11846 	}
11847 
11848 	WARN_ON_ONCE(busiest == env.dst_rq);
11849 
11850 	update_lb_imbalance_stat(&env, sd, idle);
11851 
11852 	env.src_cpu = busiest->cpu;
11853 	env.src_rq = busiest;
11854 
11855 	ld_moved = 0;
11856 	/* Clear this flag as soon as we find a pullable task */
11857 	env.flags |= LBF_ALL_PINNED;
11858 	if (busiest->nr_running > 1) {
11859 		/*
11860 		 * Attempt to move tasks. If sched_balance_find_src_group has found
11861 		 * an imbalance but busiest->nr_running <= 1, the group is
11862 		 * still unbalanced. ld_moved simply stays zero, so it is
11863 		 * correctly treated as an imbalance.
11864 		 */
11865 		env.loop_max  = min(sysctl_sched_nr_migrate, busiest->nr_running);
11866 
11867 more_balance:
11868 		rq_lock_irqsave(busiest, &rf);
11869 		update_rq_clock(busiest);
11870 
11871 		/*
11872 		 * cur_ld_moved - load moved in current iteration
11873 		 * ld_moved     - cumulative load moved across iterations
11874 		 */
11875 		cur_ld_moved = detach_tasks(&env);
11876 
11877 		/*
11878 		 * We've detached some tasks from busiest_rq. Every
11879 		 * task is masked "TASK_ON_RQ_MIGRATING", so we can safely
11880 		 * unlock busiest->lock, and we are able to be sure
11881 		 * that nobody can manipulate the tasks in parallel.
11882 		 * See task_rq_lock() family for the details.
11883 		 */
11884 
11885 		rq_unlock(busiest, &rf);
11886 
11887 		if (cur_ld_moved) {
11888 			attach_tasks(&env);
11889 			ld_moved += cur_ld_moved;
11890 		}
11891 
11892 		local_irq_restore(rf.flags);
11893 
11894 		if (env.flags & LBF_NEED_BREAK) {
11895 			env.flags &= ~LBF_NEED_BREAK;
11896 			goto more_balance;
11897 		}
11898 
11899 		/*
11900 		 * Revisit (affine) tasks on src_cpu that couldn't be moved to
11901 		 * us and move them to an alternate dst_cpu in our sched_group
11902 		 * where they can run. The upper limit on how many times we
11903 		 * iterate on same src_cpu is dependent on number of CPUs in our
11904 		 * sched_group.
11905 		 *
11906 		 * This changes load balance semantics a bit on who can move
11907 		 * load to a given_cpu. In addition to the given_cpu itself
11908 		 * (or a ilb_cpu acting on its behalf where given_cpu is
11909 		 * nohz-idle), we now have balance_cpu in a position to move
11910 		 * load to given_cpu. In rare situations, this may cause
11911 		 * conflicts (balance_cpu and given_cpu/ilb_cpu deciding
11912 		 * _independently_ and at _same_ time to move some load to
11913 		 * given_cpu) causing excess load to be moved to given_cpu.
11914 		 * This however should not happen so much in practice and
11915 		 * moreover subsequent load balance cycles should correct the
11916 		 * excess load moved.
11917 		 */
11918 		if ((env.flags & LBF_DST_PINNED) && env.imbalance > 0) {
11919 
11920 			/* Prevent to re-select dst_cpu via env's CPUs */
11921 			__cpumask_clear_cpu(env.dst_cpu, env.cpus);
11922 
11923 			env.dst_rq	 = cpu_rq(env.new_dst_cpu);
11924 			env.dst_cpu	 = env.new_dst_cpu;
11925 			env.flags	&= ~LBF_DST_PINNED;
11926 			env.loop	 = 0;
11927 			env.loop_break	 = SCHED_NR_MIGRATE_BREAK;
11928 
11929 			/*
11930 			 * Go back to "more_balance" rather than "redo" since we
11931 			 * need to continue with same src_cpu.
11932 			 */
11933 			goto more_balance;
11934 		}
11935 
11936 		/*
11937 		 * We failed to reach balance because of affinity.
11938 		 */
11939 		if (sd_parent) {
11940 			int *group_imbalance = &sd_parent->groups->sgc->imbalance;
11941 
11942 			if ((env.flags & LBF_SOME_PINNED) && env.imbalance > 0)
11943 				*group_imbalance = 1;
11944 		}
11945 
11946 		/* All tasks on this runqueue were pinned by CPU affinity */
11947 		if (unlikely(env.flags & LBF_ALL_PINNED)) {
11948 			__cpumask_clear_cpu(cpu_of(busiest), cpus);
11949 			/*
11950 			 * Attempting to continue load balancing at the current
11951 			 * sched_domain level only makes sense if there are
11952 			 * active CPUs remaining as possible busiest CPUs to
11953 			 * pull load from which are not contained within the
11954 			 * destination group that is receiving any migrated
11955 			 * load.
11956 			 */
11957 			if (!cpumask_subset(cpus, env.dst_grpmask)) {
11958 				env.loop = 0;
11959 				env.loop_break = SCHED_NR_MIGRATE_BREAK;
11960 				goto redo;
11961 			}
11962 			goto out_all_pinned;
11963 		}
11964 	}
11965 
11966 	if (!ld_moved) {
11967 		schedstat_inc(sd->lb_failed[idle]);
11968 		/*
11969 		 * Increment the failure counter only on periodic balance.
11970 		 * We do not want newidle balance, which can be very
11971 		 * frequent, pollute the failure counter causing
11972 		 * excessive cache_hot migrations and active balances.
11973 		 *
11974 		 * Similarly for migration_misfit which is not related to
11975 		 * load/util migration, don't pollute nr_balance_failed.
11976 		 */
11977 		if (idle != CPU_NEWLY_IDLE &&
11978 		    env.migration_type != migrate_misfit)
11979 			sd->nr_balance_failed++;
11980 
11981 		if (need_active_balance(&env)) {
11982 			unsigned long flags;
11983 
11984 			raw_spin_rq_lock_irqsave(busiest, flags);
11985 
11986 			/*
11987 			 * Don't kick the active_load_balance_cpu_stop,
11988 			 * if the curr task on busiest CPU can't be
11989 			 * moved to this_cpu:
11990 			 */
11991 			if (!cpumask_test_cpu(this_cpu, busiest->curr->cpus_ptr)) {
11992 				raw_spin_rq_unlock_irqrestore(busiest, flags);
11993 				goto out_one_pinned;
11994 			}
11995 
11996 			/* Record that we found at least one task that could run on this_cpu */
11997 			env.flags &= ~LBF_ALL_PINNED;
11998 
11999 			/*
12000 			 * ->active_balance synchronizes accesses to
12001 			 * ->active_balance_work.  Once set, it's cleared
12002 			 * only after active load balance is finished.
12003 			 */
12004 			if (!busiest->active_balance) {
12005 				busiest->active_balance = 1;
12006 				busiest->push_cpu = this_cpu;
12007 				active_balance = 1;
12008 			}
12009 
12010 			preempt_disable();
12011 			raw_spin_rq_unlock_irqrestore(busiest, flags);
12012 			if (active_balance) {
12013 				stop_one_cpu_nowait(cpu_of(busiest),
12014 					active_load_balance_cpu_stop, busiest,
12015 					&busiest->active_balance_work);
12016 			}
12017 			preempt_enable();
12018 		}
12019 	} else {
12020 		sd->nr_balance_failed = 0;
12021 	}
12022 
12023 	if (likely(!active_balance) || need_active_balance(&env)) {
12024 		/* We were unbalanced, so reset the balancing interval */
12025 		sd->balance_interval = sd->min_interval;
12026 	}
12027 
12028 	goto out;
12029 
12030 out_balanced:
12031 	/*
12032 	 * We reach balance although we may have faced some affinity
12033 	 * constraints. Clear the imbalance flag only if other tasks got
12034 	 * a chance to move and fix the imbalance.
12035 	 */
12036 	if (sd_parent && !(env.flags & LBF_ALL_PINNED)) {
12037 		int *group_imbalance = &sd_parent->groups->sgc->imbalance;
12038 
12039 		if (*group_imbalance)
12040 			*group_imbalance = 0;
12041 	}
12042 
12043 out_all_pinned:
12044 	/*
12045 	 * We reach balance because all tasks are pinned at this level so
12046 	 * we can't migrate them. Let the imbalance flag set so parent level
12047 	 * can try to migrate them.
12048 	 */
12049 	schedstat_inc(sd->lb_balanced[idle]);
12050 
12051 	sd->nr_balance_failed = 0;
12052 
12053 out_one_pinned:
12054 	ld_moved = 0;
12055 
12056 	/*
12057 	 * sched_balance_newidle() disregards balance intervals, so we could
12058 	 * repeatedly reach this code, which would lead to balance_interval
12059 	 * skyrocketing in a short amount of time. Skip the balance_interval
12060 	 * increase logic to avoid that.
12061 	 *
12062 	 * Similarly misfit migration which is not necessarily an indication of
12063 	 * the system being busy and requires lb to backoff to let it settle
12064 	 * down.
12065 	 */
12066 	if (env.idle == CPU_NEWLY_IDLE ||
12067 	    env.migration_type == migrate_misfit)
12068 		goto out;
12069 
12070 	/* tune up the balancing interval */
12071 	if ((env.flags & LBF_ALL_PINNED &&
12072 	     sd->balance_interval < MAX_PINNED_INTERVAL) ||
12073 	    sd->balance_interval < sd->max_interval)
12074 		sd->balance_interval *= 2;
12075 out:
12076 	if (need_unlock)
12077 		atomic_set_release(&sched_balance_running, 0);
12078 
12079 	return ld_moved;
12080 }
12081 
12082 static inline unsigned long
12083 get_sd_balance_interval(struct sched_domain *sd, int cpu_busy)
12084 {
12085 	unsigned long interval = sd->balance_interval;
12086 
12087 	if (cpu_busy)
12088 		interval *= sd->busy_factor;
12089 
12090 	/* scale ms to jiffies */
12091 	interval = msecs_to_jiffies(interval);
12092 
12093 	/*
12094 	 * Reduce likelihood of busy balancing at higher domains racing with
12095 	 * balancing at lower domains by preventing their balancing periods
12096 	 * from being multiples of each other.
12097 	 */
12098 	if (cpu_busy)
12099 		interval -= 1;
12100 
12101 	interval = clamp(interval, 1UL, max_load_balance_interval);
12102 
12103 	return interval;
12104 }
12105 
12106 static inline void
12107 update_next_balance(struct sched_domain *sd, unsigned long *next_balance)
12108 {
12109 	unsigned long interval, next;
12110 
12111 	/* used by idle balance, so cpu_busy = 0 */
12112 	interval = get_sd_balance_interval(sd, 0);
12113 	next = sd->last_balance + interval;
12114 
12115 	if (time_after(*next_balance, next))
12116 		*next_balance = next;
12117 }
12118 
12119 /*
12120  * active_load_balance_cpu_stop is run by the CPU stopper. It pushes
12121  * running tasks off the busiest CPU onto idle CPUs. It requires at
12122  * least 1 task to be running on each physical CPU where possible, and
12123  * avoids physical / logical imbalances.
12124  */
12125 static int active_load_balance_cpu_stop(void *data)
12126 {
12127 	struct rq *busiest_rq = data;
12128 	int busiest_cpu = cpu_of(busiest_rq);
12129 	int target_cpu = busiest_rq->push_cpu;
12130 	struct rq *target_rq = cpu_rq(target_cpu);
12131 	struct sched_domain *sd;
12132 	struct task_struct *p = NULL;
12133 	struct rq_flags rf;
12134 
12135 	rq_lock_irq(busiest_rq, &rf);
12136 	/*
12137 	 * Between queueing the stop-work and running it is a hole in which
12138 	 * CPUs can become inactive. We should not move tasks from or to
12139 	 * inactive CPUs.
12140 	 */
12141 	if (!cpu_active(busiest_cpu) || !cpu_active(target_cpu))
12142 		goto out_unlock;
12143 
12144 	/* Make sure the requested CPU hasn't gone down in the meantime: */
12145 	if (unlikely(busiest_cpu != smp_processor_id() ||
12146 		     !busiest_rq->active_balance))
12147 		goto out_unlock;
12148 
12149 	/* Is there any task to move? */
12150 	if (busiest_rq->nr_running <= 1)
12151 		goto out_unlock;
12152 
12153 	/*
12154 	 * This condition is "impossible", if it occurs
12155 	 * we need to fix it. Originally reported by
12156 	 * Bjorn Helgaas on a 128-CPU setup.
12157 	 */
12158 	WARN_ON_ONCE(busiest_rq == target_rq);
12159 
12160 	/* Search for an sd spanning us and the target CPU. */
12161 	rcu_read_lock();
12162 	for_each_domain(target_cpu, sd) {
12163 		if (cpumask_test_cpu(busiest_cpu, sched_domain_span(sd)))
12164 			break;
12165 	}
12166 
12167 	if (likely(sd)) {
12168 		struct lb_env env = {
12169 			.sd		= sd,
12170 			.dst_cpu	= target_cpu,
12171 			.dst_rq		= target_rq,
12172 			.src_cpu	= busiest_rq->cpu,
12173 			.src_rq		= busiest_rq,
12174 			.idle		= CPU_IDLE,
12175 			.flags		= LBF_ACTIVE_LB,
12176 		};
12177 
12178 		schedstat_inc(sd->alb_count);
12179 		update_rq_clock(busiest_rq);
12180 
12181 		p = detach_one_task(&env);
12182 		if (p) {
12183 			schedstat_inc(sd->alb_pushed);
12184 			/* Active balancing done, reset the failure counter. */
12185 			sd->nr_balance_failed = 0;
12186 		} else {
12187 			schedstat_inc(sd->alb_failed);
12188 		}
12189 	}
12190 	rcu_read_unlock();
12191 out_unlock:
12192 	busiest_rq->active_balance = 0;
12193 	rq_unlock(busiest_rq, &rf);
12194 
12195 	if (p)
12196 		attach_one_task(target_rq, p);
12197 
12198 	local_irq_enable();
12199 
12200 	return 0;
12201 }
12202 
12203 /*
12204  * Scale the max sched_balance_rq interval with the number of CPUs in the system.
12205  * This trades load-balance latency on larger machines for less cross talk.
12206  */
12207 void update_max_interval(void)
12208 {
12209 	max_load_balance_interval = HZ*num_online_cpus()/10;
12210 }
12211 
12212 static inline void update_newidle_stats(struct sched_domain *sd, unsigned int success)
12213 {
12214 	sd->newidle_call++;
12215 	sd->newidle_success += success;
12216 
12217 	if (sd->newidle_call >= 1024) {
12218 		sd->newidle_ratio = sd->newidle_success;
12219 		sd->newidle_call /= 2;
12220 		sd->newidle_success /= 2;
12221 	}
12222 }
12223 
12224 static inline bool
12225 update_newidle_cost(struct sched_domain *sd, u64 cost, unsigned int success)
12226 {
12227 	unsigned long next_decay = sd->last_decay_max_lb_cost + HZ;
12228 	unsigned long now = jiffies;
12229 
12230 	if (cost)
12231 		update_newidle_stats(sd, success);
12232 
12233 	if (cost > sd->max_newidle_lb_cost) {
12234 		/*
12235 		 * Track max cost of a domain to make sure to not delay the
12236 		 * next wakeup on the CPU.
12237 		 */
12238 		sd->max_newidle_lb_cost = cost;
12239 		sd->last_decay_max_lb_cost = now;
12240 
12241 	} else if (time_after(now, next_decay)) {
12242 		/*
12243 		 * Decay the newidle max times by ~1% per second to ensure that
12244 		 * it is not outdated and the current max cost is actually
12245 		 * shorter.
12246 		 */
12247 		sd->max_newidle_lb_cost = (sd->max_newidle_lb_cost * 253) / 256;
12248 		sd->last_decay_max_lb_cost = now;
12249 		return true;
12250 	}
12251 
12252 	return false;
12253 }
12254 
12255 /*
12256  * It checks each scheduling domain to see if it is due to be balanced,
12257  * and initiates a balancing operation if so.
12258  *
12259  * Balancing parameters are set up in init_sched_domains.
12260  */
12261 static void sched_balance_domains(struct rq *rq, enum cpu_idle_type idle)
12262 {
12263 	int continue_balancing = 1;
12264 	int cpu = rq->cpu;
12265 	int busy = idle != CPU_IDLE && !sched_idle_cpu(cpu);
12266 	unsigned long interval;
12267 	struct sched_domain *sd;
12268 	/* Earliest time when we have to do rebalance again */
12269 	unsigned long next_balance = jiffies + 60*HZ;
12270 	int update_next_balance = 0;
12271 	int need_decay = 0;
12272 	u64 max_cost = 0;
12273 
12274 	rcu_read_lock();
12275 	for_each_domain(cpu, sd) {
12276 		/*
12277 		 * Decay the newidle max times here because this is a regular
12278 		 * visit to all the domains.
12279 		 */
12280 		need_decay = update_newidle_cost(sd, 0, 0);
12281 		max_cost += sd->max_newidle_lb_cost;
12282 
12283 		/*
12284 		 * Stop the load balance at this level. There is another
12285 		 * CPU in our sched group which is doing load balancing more
12286 		 * actively.
12287 		 */
12288 		if (!continue_balancing) {
12289 			if (need_decay)
12290 				continue;
12291 			break;
12292 		}
12293 
12294 		interval = get_sd_balance_interval(sd, busy);
12295 		if (time_after_eq(jiffies, sd->last_balance + interval)) {
12296 			if (sched_balance_rq(cpu, rq, sd, idle, &continue_balancing)) {
12297 				/*
12298 				 * The LBF_DST_PINNED logic could have changed
12299 				 * env->dst_cpu, so we can't know our idle
12300 				 * state even if we migrated tasks. Update it.
12301 				 */
12302 				idle = idle_cpu(cpu);
12303 				busy = !idle && !sched_idle_cpu(cpu);
12304 			}
12305 			sd->last_balance = jiffies;
12306 			interval = get_sd_balance_interval(sd, busy);
12307 		}
12308 		if (time_after(next_balance, sd->last_balance + interval)) {
12309 			next_balance = sd->last_balance + interval;
12310 			update_next_balance = 1;
12311 		}
12312 	}
12313 	if (need_decay) {
12314 		/*
12315 		 * Ensure the rq-wide value also decays but keep it at a
12316 		 * reasonable floor to avoid funnies with rq->avg_idle.
12317 		 */
12318 		rq->max_idle_balance_cost =
12319 			max((u64)sysctl_sched_migration_cost, max_cost);
12320 	}
12321 	rcu_read_unlock();
12322 
12323 	/*
12324 	 * next_balance will be updated only when there is a need.
12325 	 * When the cpu is attached to null domain for ex, it will not be
12326 	 * updated.
12327 	 */
12328 	if (likely(update_next_balance))
12329 		rq->next_balance = next_balance;
12330 
12331 }
12332 
12333 static inline int on_null_domain(struct rq *rq)
12334 {
12335 	return unlikely(!rcu_dereference_sched(rq->sd));
12336 }
12337 
12338 #ifdef CONFIG_NO_HZ_COMMON
12339 /*
12340  * NOHZ idle load balancing (ILB) details:
12341  *
12342  * - When one of the busy CPUs notices that there may be an idle rebalancing
12343  *   needed, they will kick the idle load balancer, which then does idle
12344  *   load balancing for all the idle CPUs.
12345  */
12346 static inline int find_new_ilb(void)
12347 {
12348 	const struct cpumask *hk_mask;
12349 	int ilb_cpu;
12350 
12351 	hk_mask = housekeeping_cpumask(HK_TYPE_KERNEL_NOISE);
12352 
12353 	for_each_cpu_and(ilb_cpu, nohz.idle_cpus_mask, hk_mask) {
12354 
12355 		if (ilb_cpu == smp_processor_id())
12356 			continue;
12357 
12358 		if (idle_cpu(ilb_cpu))
12359 			return ilb_cpu;
12360 	}
12361 
12362 	return -1;
12363 }
12364 
12365 /*
12366  * Kick a CPU to do the NOHZ balancing, if it is time for it, via a cross-CPU
12367  * SMP function call (IPI).
12368  *
12369  * We pick the first idle CPU in the HK_TYPE_KERNEL_NOISE housekeeping set
12370  * (if there is one).
12371  */
12372 static void kick_ilb(unsigned int flags)
12373 {
12374 	int ilb_cpu;
12375 
12376 	/*
12377 	 * Increase nohz.next_balance only when if full ilb is triggered but
12378 	 * not if we only update stats.
12379 	 */
12380 	if (flags & NOHZ_BALANCE_KICK)
12381 		nohz.next_balance = jiffies+1;
12382 
12383 	ilb_cpu = find_new_ilb();
12384 	if (ilb_cpu < 0)
12385 		return;
12386 
12387 	/*
12388 	 * Don't bother if no new NOHZ balance work items for ilb_cpu,
12389 	 * i.e. all bits in flags are already set in ilb_cpu.
12390 	 */
12391 	if ((atomic_read(nohz_flags(ilb_cpu)) & flags) == flags)
12392 		return;
12393 
12394 	/*
12395 	 * Access to rq::nohz_csd is serialized by NOHZ_KICK_MASK; he who sets
12396 	 * the first flag owns it; cleared by nohz_csd_func().
12397 	 */
12398 	flags = atomic_fetch_or(flags, nohz_flags(ilb_cpu));
12399 	if (flags & NOHZ_KICK_MASK)
12400 		return;
12401 
12402 	/*
12403 	 * This way we generate an IPI on the target CPU which
12404 	 * is idle, and the softirq performing NOHZ idle load balancing
12405 	 * will be run before returning from the IPI.
12406 	 */
12407 	smp_call_function_single_async(ilb_cpu, &cpu_rq(ilb_cpu)->nohz_csd);
12408 }
12409 
12410 /*
12411  * Current decision point for kicking the idle load balancer in the presence
12412  * of idle CPUs in the system.
12413  */
12414 static void nohz_balancer_kick(struct rq *rq)
12415 {
12416 	unsigned long now = jiffies;
12417 	struct sched_domain_shared *sds;
12418 	struct sched_domain *sd;
12419 	int nr_busy, i, cpu = rq->cpu;
12420 	unsigned int flags = 0;
12421 
12422 	if (unlikely(rq->idle_balance))
12423 		return;
12424 
12425 	/*
12426 	 * We may be recently in ticked or tickless idle mode. At the first
12427 	 * busy tick after returning from idle, we will update the busy stats.
12428 	 */
12429 	nohz_balance_exit_idle(rq);
12430 
12431 	if (READ_ONCE(nohz.has_blocked_load) &&
12432 	    time_after(now, READ_ONCE(nohz.next_blocked)))
12433 		flags = NOHZ_STATS_KICK;
12434 
12435 	/*
12436 	 * Most of the time system is not 100% busy. i.e nohz.nr_cpus > 0
12437 	 * Skip the read if time is not due.
12438 	 *
12439 	 * If none are in tickless mode, there maybe a narrow window
12440 	 * (28 jiffies, HZ=1000) where flags maybe set and kick_ilb called.
12441 	 * But idle load balancing is not done as find_new_ilb fails.
12442 	 * That's very rare. So read nohz.nr_cpus only if time is due.
12443 	 */
12444 	if (time_before(now, nohz.next_balance))
12445 		goto out;
12446 
12447 	/*
12448 	 * None are in tickless mode and hence no need for NOHZ idle load
12449 	 * balancing
12450 	 */
12451 	if (unlikely(cpumask_empty(nohz.idle_cpus_mask)))
12452 		return;
12453 
12454 	if (rq->nr_running >= 2) {
12455 		flags = NOHZ_STATS_KICK | NOHZ_BALANCE_KICK;
12456 		goto out;
12457 	}
12458 
12459 	rcu_read_lock();
12460 
12461 	sd = rcu_dereference_all(rq->sd);
12462 	if (sd) {
12463 		/*
12464 		 * If there's a runnable CFS task and the current CPU has reduced
12465 		 * capacity, kick the ILB to see if there's a better CPU to run on:
12466 		 */
12467 		if (rq->cfs.h_nr_runnable >= 1 && check_cpu_capacity(rq, sd)) {
12468 			flags = NOHZ_STATS_KICK | NOHZ_BALANCE_KICK;
12469 			goto unlock;
12470 		}
12471 	}
12472 
12473 	sd = rcu_dereference_all(per_cpu(sd_asym_packing, cpu));
12474 	if (sd) {
12475 		/*
12476 		 * When ASYM_PACKING; see if there's a more preferred CPU
12477 		 * currently idle; in which case, kick the ILB to move tasks
12478 		 * around.
12479 		 *
12480 		 * When balancing between cores, all the SMT siblings of the
12481 		 * preferred CPU must be idle.
12482 		 */
12483 		for_each_cpu_and(i, sched_domain_span(sd), nohz.idle_cpus_mask) {
12484 			if (sched_asym(sd, i, cpu)) {
12485 				flags = NOHZ_STATS_KICK | NOHZ_BALANCE_KICK;
12486 				goto unlock;
12487 			}
12488 		}
12489 	}
12490 
12491 	sd = rcu_dereference_all(per_cpu(sd_asym_cpucapacity, cpu));
12492 	if (sd) {
12493 		/*
12494 		 * When ASYM_CPUCAPACITY; see if there's a higher capacity CPU
12495 		 * to run the misfit task on.
12496 		 */
12497 		if (check_misfit_status(rq)) {
12498 			flags = NOHZ_STATS_KICK | NOHZ_BALANCE_KICK;
12499 			goto unlock;
12500 		}
12501 
12502 		/*
12503 		 * For asymmetric systems, we do not want to nicely balance
12504 		 * cache use, instead we want to embrace asymmetry and only
12505 		 * ensure tasks have enough CPU capacity.
12506 		 *
12507 		 * Skip the LLC logic because it's not relevant in that case.
12508 		 */
12509 		goto unlock;
12510 	}
12511 
12512 	sds = rcu_dereference_all(per_cpu(sd_llc_shared, cpu));
12513 	if (sds) {
12514 		/*
12515 		 * If there is an imbalance between LLC domains (IOW we could
12516 		 * increase the overall cache utilization), we need a less-loaded LLC
12517 		 * domain to pull some load from. Likewise, we may need to spread
12518 		 * load within the current LLC domain (e.g. packed SMT cores but
12519 		 * other CPUs are idle). We can't really know from here how busy
12520 		 * the others are - so just get a NOHZ balance going if it looks
12521 		 * like this LLC domain has tasks we could move.
12522 		 */
12523 		nr_busy = atomic_read(&sds->nr_busy_cpus);
12524 		if (nr_busy > 1) {
12525 			flags = NOHZ_STATS_KICK | NOHZ_BALANCE_KICK;
12526 			goto unlock;
12527 		}
12528 	}
12529 unlock:
12530 	rcu_read_unlock();
12531 out:
12532 	if (READ_ONCE(nohz.needs_update))
12533 		flags |= NOHZ_NEXT_KICK;
12534 
12535 	if (flags)
12536 		kick_ilb(flags);
12537 }
12538 
12539 static void set_cpu_sd_state_busy(int cpu)
12540 {
12541 	struct sched_domain *sd;
12542 
12543 	rcu_read_lock();
12544 	sd = rcu_dereference_all(per_cpu(sd_llc, cpu));
12545 
12546 	if (!sd || !sd->nohz_idle)
12547 		goto unlock;
12548 	sd->nohz_idle = 0;
12549 
12550 	atomic_inc(&sd->shared->nr_busy_cpus);
12551 unlock:
12552 	rcu_read_unlock();
12553 }
12554 
12555 void nohz_balance_exit_idle(struct rq *rq)
12556 {
12557 	WARN_ON_ONCE(rq != this_rq());
12558 
12559 	if (likely(!rq->nohz_tick_stopped))
12560 		return;
12561 
12562 	rq->nohz_tick_stopped = 0;
12563 	cpumask_clear_cpu(rq->cpu, nohz.idle_cpus_mask);
12564 
12565 	set_cpu_sd_state_busy(rq->cpu);
12566 }
12567 
12568 static void set_cpu_sd_state_idle(int cpu)
12569 {
12570 	struct sched_domain *sd;
12571 
12572 	rcu_read_lock();
12573 	sd = rcu_dereference_all(per_cpu(sd_llc, cpu));
12574 
12575 	if (!sd || sd->nohz_idle)
12576 		goto unlock;
12577 	sd->nohz_idle = 1;
12578 
12579 	atomic_dec(&sd->shared->nr_busy_cpus);
12580 unlock:
12581 	rcu_read_unlock();
12582 }
12583 
12584 /*
12585  * This routine will record that the CPU is going idle with tick stopped.
12586  * This info will be used in performing idle load balancing in the future.
12587  */
12588 void nohz_balance_enter_idle(int cpu)
12589 {
12590 	struct rq *rq = cpu_rq(cpu);
12591 
12592 	WARN_ON_ONCE(cpu != smp_processor_id());
12593 
12594 	/* If this CPU is going down, then nothing needs to be done: */
12595 	if (!cpu_active(cpu))
12596 		return;
12597 
12598 	/*
12599 	 * Can be set safely without rq->lock held
12600 	 * If a clear happens, it will have evaluated last additions because
12601 	 * rq->lock is held during the check and the clear
12602 	 */
12603 	rq->has_blocked_load = 1;
12604 
12605 	/*
12606 	 * The tick is still stopped but load could have been added in the
12607 	 * meantime. We set the nohz.has_blocked_load flag to trig a check of the
12608 	 * *_avg. The CPU is already part of nohz.idle_cpus_mask so the clear
12609 	 * of nohz.has_blocked_load can only happen after checking the new load
12610 	 */
12611 	if (rq->nohz_tick_stopped)
12612 		goto out;
12613 
12614 	/* If we're a completely isolated CPU, we don't play: */
12615 	if (on_null_domain(rq))
12616 		return;
12617 
12618 	rq->nohz_tick_stopped = 1;
12619 
12620 	cpumask_set_cpu(cpu, nohz.idle_cpus_mask);
12621 
12622 	/*
12623 	 * Ensures that if nohz_idle_balance() fails to observe our
12624 	 * @idle_cpus_mask store, it must observe the @has_blocked_load
12625 	 * and @needs_update stores.
12626 	 */
12627 	smp_mb__after_atomic();
12628 
12629 	set_cpu_sd_state_idle(cpu);
12630 
12631 	WRITE_ONCE(nohz.needs_update, 1);
12632 out:
12633 	/*
12634 	 * Each time a cpu enter idle, we assume that it has blocked load and
12635 	 * enable the periodic update of the load of idle CPUs
12636 	 */
12637 	WRITE_ONCE(nohz.has_blocked_load, 1);
12638 }
12639 
12640 static bool update_nohz_stats(struct rq *rq)
12641 {
12642 	unsigned int cpu = rq->cpu;
12643 
12644 	if (!rq->has_blocked_load)
12645 		return false;
12646 
12647 	if (!cpumask_test_cpu(cpu, nohz.idle_cpus_mask))
12648 		return false;
12649 
12650 	if (!time_after(jiffies, READ_ONCE(rq->last_blocked_load_update_tick)))
12651 		return true;
12652 
12653 	sched_balance_update_blocked_averages(cpu);
12654 
12655 	return rq->has_blocked_load;
12656 }
12657 
12658 /*
12659  * Internal function that runs load balance for all idle CPUs. The load balance
12660  * can be a simple update of blocked load or a complete load balance with
12661  * tasks movement depending of flags.
12662  */
12663 static void _nohz_idle_balance(struct rq *this_rq, unsigned int flags)
12664 {
12665 	/* Earliest time when we have to do rebalance again */
12666 	unsigned long now = jiffies;
12667 	unsigned long next_balance = now + 60*HZ;
12668 	bool has_blocked_load = false;
12669 	int update_next_balance = 0;
12670 	int this_cpu = this_rq->cpu;
12671 	int balance_cpu;
12672 	struct rq *rq;
12673 
12674 	WARN_ON_ONCE((flags & NOHZ_KICK_MASK) == NOHZ_BALANCE_KICK);
12675 
12676 	/*
12677 	 * We assume there will be no idle load after this update and clear
12678 	 * the has_blocked_load flag. If a cpu enters idle in the mean time, it will
12679 	 * set the has_blocked_load flag and trigger another update of idle load.
12680 	 * Because a cpu that becomes idle, is added to idle_cpus_mask before
12681 	 * setting the flag, we are sure to not clear the state and not
12682 	 * check the load of an idle cpu.
12683 	 *
12684 	 * Same applies to idle_cpus_mask vs needs_update.
12685 	 */
12686 	if (flags & NOHZ_STATS_KICK)
12687 		WRITE_ONCE(nohz.has_blocked_load, 0);
12688 	if (flags & NOHZ_NEXT_KICK)
12689 		WRITE_ONCE(nohz.needs_update, 0);
12690 
12691 	/*
12692 	 * Ensures that if we miss the CPU, we must see the has_blocked_load
12693 	 * store from nohz_balance_enter_idle().
12694 	 */
12695 	smp_mb();
12696 
12697 	/*
12698 	 * Start with the next CPU after this_cpu so we will end with this_cpu and let a
12699 	 * chance for other idle cpu to pull load.
12700 	 */
12701 	for_each_cpu_wrap(balance_cpu,  nohz.idle_cpus_mask, this_cpu+1) {
12702 		if (!idle_cpu(balance_cpu))
12703 			continue;
12704 
12705 		/*
12706 		 * If this CPU gets work to do, stop the load balancing
12707 		 * work being done for other CPUs. Next load
12708 		 * balancing owner will pick it up.
12709 		 */
12710 		if (!idle_cpu(this_cpu) && need_resched()) {
12711 			if (flags & NOHZ_STATS_KICK)
12712 				has_blocked_load = true;
12713 			if (flags & NOHZ_NEXT_KICK)
12714 				WRITE_ONCE(nohz.needs_update, 1);
12715 			goto abort;
12716 		}
12717 
12718 		rq = cpu_rq(balance_cpu);
12719 
12720 		if (flags & NOHZ_STATS_KICK)
12721 			has_blocked_load |= update_nohz_stats(rq);
12722 
12723 		/*
12724 		 * If time for next balance is due,
12725 		 * do the balance.
12726 		 */
12727 		if (time_after_eq(jiffies, rq->next_balance)) {
12728 			struct rq_flags rf;
12729 
12730 			rq_lock_irqsave(rq, &rf);
12731 			update_rq_clock(rq);
12732 			rq_unlock_irqrestore(rq, &rf);
12733 
12734 			if (flags & NOHZ_BALANCE_KICK)
12735 				sched_balance_domains(rq, CPU_IDLE);
12736 		}
12737 
12738 		if (time_after(next_balance, rq->next_balance)) {
12739 			next_balance = rq->next_balance;
12740 			update_next_balance = 1;
12741 		}
12742 	}
12743 
12744 	/*
12745 	 * next_balance will be updated only when there is a need.
12746 	 * When the CPU is attached to null domain for ex, it will not be
12747 	 * updated.
12748 	 */
12749 	if (likely(update_next_balance))
12750 		nohz.next_balance = next_balance;
12751 
12752 	if (flags & NOHZ_STATS_KICK)
12753 		WRITE_ONCE(nohz.next_blocked,
12754 			   now + msecs_to_jiffies(LOAD_AVG_PERIOD));
12755 
12756 abort:
12757 	/* There is still blocked load, enable periodic update */
12758 	if (has_blocked_load)
12759 		WRITE_ONCE(nohz.has_blocked_load, 1);
12760 }
12761 
12762 /*
12763  * In CONFIG_NO_HZ_COMMON case, the idle balance kickee will do the
12764  * rebalancing for all the CPUs for whom scheduler ticks are stopped.
12765  */
12766 static bool nohz_idle_balance(struct rq *this_rq, enum cpu_idle_type idle)
12767 {
12768 	unsigned int flags = this_rq->nohz_idle_balance;
12769 
12770 	if (!flags)
12771 		return false;
12772 
12773 	this_rq->nohz_idle_balance = 0;
12774 
12775 	if (idle != CPU_IDLE)
12776 		return false;
12777 
12778 	_nohz_idle_balance(this_rq, flags);
12779 
12780 	return true;
12781 }
12782 
12783 /*
12784  * Check if we need to directly run the ILB for updating blocked load before
12785  * entering idle state. Here we run ILB directly without issuing IPIs.
12786  *
12787  * Note that when this function is called, the tick may not yet be stopped on
12788  * this CPU yet. nohz.idle_cpus_mask is updated only when tick is stopped and
12789  * cleared on the next busy tick. In other words, nohz.idle_cpus_mask updates
12790  * don't align with CPUs enter/exit idle to avoid bottlenecks due to high idle
12791  * entry/exit rate (usec). So it is possible that _nohz_idle_balance() is
12792  * called from this function on (this) CPU that's not yet in the mask. That's
12793  * OK because the goal of nohz_run_idle_balance() is to run ILB only for
12794  * updating the blocked load of already idle CPUs without waking up one of
12795  * those idle CPUs and outside the preempt disable / IRQ off phase of the local
12796  * cpu about to enter idle, because it can take a long time.
12797  */
12798 void nohz_run_idle_balance(int cpu)
12799 {
12800 	unsigned int flags;
12801 
12802 	flags = atomic_fetch_andnot(NOHZ_NEWILB_KICK, nohz_flags(cpu));
12803 
12804 	/*
12805 	 * Update the blocked load only if no SCHED_SOFTIRQ is about to happen
12806 	 * (i.e. NOHZ_STATS_KICK set) and will do the same.
12807 	 */
12808 	if ((flags == NOHZ_NEWILB_KICK) && !need_resched())
12809 		_nohz_idle_balance(cpu_rq(cpu), NOHZ_STATS_KICK);
12810 }
12811 
12812 static void nohz_newidle_balance(struct rq *this_rq)
12813 {
12814 	int this_cpu = this_rq->cpu;
12815 
12816 	/* Will wake up very soon. No time for doing anything else*/
12817 	if (this_rq->avg_idle < sysctl_sched_migration_cost)
12818 		return;
12819 
12820 	/* Don't need to update blocked load of idle CPUs*/
12821 	if (!READ_ONCE(nohz.has_blocked_load) ||
12822 	    time_before(jiffies, READ_ONCE(nohz.next_blocked)))
12823 		return;
12824 
12825 	/*
12826 	 * Set the need to trigger ILB in order to update blocked load
12827 	 * before entering idle state.
12828 	 */
12829 	atomic_or(NOHZ_NEWILB_KICK, nohz_flags(this_cpu));
12830 }
12831 
12832 #else /* !CONFIG_NO_HZ_COMMON: */
12833 static inline void nohz_balancer_kick(struct rq *rq) { }
12834 
12835 static inline bool nohz_idle_balance(struct rq *this_rq, enum cpu_idle_type idle)
12836 {
12837 	return false;
12838 }
12839 
12840 static inline void nohz_newidle_balance(struct rq *this_rq) { }
12841 #endif /* !CONFIG_NO_HZ_COMMON */
12842 
12843 /*
12844  * sched_balance_newidle is called by schedule() if this_cpu is about to become
12845  * idle. Attempts to pull tasks from other CPUs.
12846  *
12847  * Returns:
12848  *   < 0 - we released the lock and there are !fair tasks present
12849  *     0 - failed, no new tasks
12850  *   > 0 - success, new (fair) tasks present
12851  */
12852 static int sched_balance_newidle(struct rq *this_rq, struct rq_flags *rf)
12853 	__must_hold(__rq_lockp(this_rq))
12854 {
12855 	unsigned long next_balance = jiffies + HZ;
12856 	int this_cpu = this_rq->cpu;
12857 	int continue_balancing = 1;
12858 	u64 t0, t1, curr_cost = 0;
12859 	struct sched_domain *sd;
12860 	int pulled_task = 0;
12861 
12862 	update_misfit_status(NULL, this_rq);
12863 
12864 	/*
12865 	 * There is a task waiting to run. No need to search for one.
12866 	 * Return 0; the task will be enqueued when switching to idle.
12867 	 */
12868 	if (this_rq->ttwu_pending)
12869 		return 0;
12870 
12871 	/*
12872 	 * We must set idle_stamp _before_ calling sched_balance_rq()
12873 	 * for CPU_NEWLY_IDLE, such that we measure the this duration
12874 	 * as idle time.
12875 	 */
12876 	this_rq->idle_stamp = rq_clock(this_rq);
12877 
12878 	/*
12879 	 * Do not pull tasks towards !active CPUs...
12880 	 */
12881 	if (!cpu_active(this_cpu))
12882 		return 0;
12883 
12884 	/*
12885 	 * This is OK, because current is on_cpu, which avoids it being picked
12886 	 * for load-balance and preemption/IRQs are still disabled avoiding
12887 	 * further scheduler activity on it and we're being very careful to
12888 	 * re-start the picking loop.
12889 	 */
12890 	rq_unpin_lock(this_rq, rf);
12891 
12892 	sd = rcu_dereference_sched_domain(this_rq->sd);
12893 	if (!sd)
12894 		goto out;
12895 
12896 	if (!get_rd_overloaded(this_rq->rd) ||
12897 	    this_rq->avg_idle < sd->max_newidle_lb_cost) {
12898 
12899 		update_next_balance(sd, &next_balance);
12900 		goto out;
12901 	}
12902 
12903 	/*
12904 	 * Include sched_balance_update_blocked_averages() in the cost
12905 	 * calculation because it can be quite costly -- this ensures we skip
12906 	 * it when avg_idle gets to be very low.
12907 	 */
12908 	t0 = sched_clock_cpu(this_cpu);
12909 	__sched_balance_update_blocked_averages(this_rq);
12910 
12911 	this_rq->next_class = &fair_sched_class;
12912 	raw_spin_rq_unlock(this_rq);
12913 
12914 	for_each_domain(this_cpu, sd) {
12915 		u64 domain_cost;
12916 
12917 		update_next_balance(sd, &next_balance);
12918 
12919 		if (this_rq->avg_idle < curr_cost + sd->max_newidle_lb_cost)
12920 			break;
12921 
12922 		if (sd->flags & SD_BALANCE_NEWIDLE) {
12923 			unsigned int weight = 1;
12924 
12925 			if (sched_feat(NI_RANDOM)) {
12926 				/*
12927 				 * Throw a 1k sided dice; and only run
12928 				 * newidle_balance according to the success
12929 				 * rate.
12930 				 */
12931 				u32 d1k = sched_rng() % 1024;
12932 				weight = 1 + sd->newidle_ratio;
12933 				if (d1k > weight) {
12934 					update_newidle_stats(sd, 0);
12935 					continue;
12936 				}
12937 				weight = (1024 + weight/2) / weight;
12938 			}
12939 
12940 			pulled_task = sched_balance_rq(this_cpu, this_rq,
12941 						   sd, CPU_NEWLY_IDLE,
12942 						   &continue_balancing);
12943 
12944 			t1 = sched_clock_cpu(this_cpu);
12945 			domain_cost = t1 - t0;
12946 			curr_cost += domain_cost;
12947 			t0 = t1;
12948 
12949 			/*
12950 			 * Track max cost of a domain to make sure to not delay the
12951 			 * next wakeup on the CPU.
12952 			 */
12953 			update_newidle_cost(sd, domain_cost, weight * !!pulled_task);
12954 		}
12955 
12956 		/*
12957 		 * Stop searching for tasks to pull if there are
12958 		 * now runnable tasks on this rq.
12959 		 */
12960 		if (pulled_task || !continue_balancing)
12961 			break;
12962 	}
12963 
12964 	raw_spin_rq_lock(this_rq);
12965 
12966 	if (curr_cost > this_rq->max_idle_balance_cost)
12967 		this_rq->max_idle_balance_cost = curr_cost;
12968 
12969 	/*
12970 	 * While browsing the domains, we released the rq lock, a task could
12971 	 * have been enqueued in the meantime. Since we're not going idle,
12972 	 * pretend we pulled a task.
12973 	 */
12974 	if (this_rq->cfs.h_nr_queued && !pulled_task)
12975 		pulled_task = 1;
12976 
12977 	/* If a higher prio class was modified, restart the pick */
12978 	if (sched_class_above(this_rq->next_class, &fair_sched_class))
12979 		pulled_task = -1;
12980 
12981 out:
12982 	/* Move the next balance forward */
12983 	if (time_after(this_rq->next_balance, next_balance))
12984 		this_rq->next_balance = next_balance;
12985 
12986 	if (pulled_task)
12987 		this_rq->idle_stamp = 0;
12988 	else
12989 		nohz_newidle_balance(this_rq);
12990 
12991 	rq_repin_lock(this_rq, rf);
12992 
12993 	return pulled_task;
12994 }
12995 
12996 /*
12997  * This softirq handler is triggered via SCHED_SOFTIRQ from two places:
12998  *
12999  * - directly from the local sched_tick() for periodic load balancing
13000  *
13001  * - indirectly from a remote sched_tick() for NOHZ idle balancing
13002  *   through the SMP cross-call nohz_csd_func()
13003  */
13004 static __latent_entropy void sched_balance_softirq(void)
13005 {
13006 	struct rq *this_rq = this_rq();
13007 	enum cpu_idle_type idle = this_rq->idle_balance;
13008 	/*
13009 	 * If this CPU has a pending NOHZ_BALANCE_KICK, then do the
13010 	 * balancing on behalf of the other idle CPUs whose ticks are
13011 	 * stopped. Do nohz_idle_balance *before* sched_balance_domains to
13012 	 * give the idle CPUs a chance to load balance. Else we may
13013 	 * load balance only within the local sched_domain hierarchy
13014 	 * and abort nohz_idle_balance altogether if we pull some load.
13015 	 */
13016 	if (nohz_idle_balance(this_rq, idle))
13017 		return;
13018 
13019 	/* normal load balance */
13020 	sched_balance_update_blocked_averages(this_rq->cpu);
13021 	sched_balance_domains(this_rq, idle);
13022 }
13023 
13024 /*
13025  * Trigger the SCHED_SOFTIRQ if it is time to do periodic load balancing.
13026  */
13027 void sched_balance_trigger(struct rq *rq)
13028 {
13029 	/*
13030 	 * Don't need to rebalance while attached to NULL domain or
13031 	 * runqueue CPU is not active
13032 	 */
13033 	if (unlikely(on_null_domain(rq) || !cpu_active(cpu_of(rq))))
13034 		return;
13035 
13036 	if (time_after_eq(jiffies, rq->next_balance))
13037 		raise_softirq(SCHED_SOFTIRQ);
13038 
13039 	nohz_balancer_kick(rq);
13040 }
13041 
13042 static void rq_online_fair(struct rq *rq)
13043 {
13044 	update_sysctl();
13045 
13046 	update_runtime_enabled(rq);
13047 }
13048 
13049 static void rq_offline_fair(struct rq *rq)
13050 {
13051 	update_sysctl();
13052 
13053 	/* Ensure any throttled groups are reachable by pick_next_task */
13054 	unthrottle_offline_cfs_rqs(rq);
13055 
13056 	/* Ensure that we remove rq contribution to group share: */
13057 	clear_tg_offline_cfs_rqs(rq);
13058 }
13059 
13060 #ifdef CONFIG_SCHED_CORE
13061 static inline bool
13062 __entity_slice_used(struct sched_entity *se, int min_nr_tasks)
13063 {
13064 	u64 rtime = se->sum_exec_runtime - se->prev_sum_exec_runtime;
13065 	u64 slice = se->slice;
13066 
13067 	return (rtime * min_nr_tasks > slice);
13068 }
13069 
13070 #define MIN_NR_TASKS_DURING_FORCEIDLE	2
13071 static inline void task_tick_core(struct rq *rq, struct task_struct *curr)
13072 {
13073 	if (!sched_core_enabled(rq))
13074 		return;
13075 
13076 	/*
13077 	 * If runqueue has only one task which used up its slice and
13078 	 * if the sibling is forced idle, then trigger schedule to
13079 	 * give forced idle task a chance.
13080 	 *
13081 	 * sched_slice() considers only this active rq and it gets the
13082 	 * whole slice. But during force idle, we have siblings acting
13083 	 * like a single runqueue and hence we need to consider runnable
13084 	 * tasks on this CPU and the forced idle CPU. Ideally, we should
13085 	 * go through the forced idle rq, but that would be a perf hit.
13086 	 * We can assume that the forced idle CPU has at least
13087 	 * MIN_NR_TASKS_DURING_FORCEIDLE - 1 tasks and use that to check
13088 	 * if we need to give up the CPU.
13089 	 */
13090 	if (rq->core->core_forceidle_count && rq->cfs.nr_queued == 1 &&
13091 	    __entity_slice_used(&curr->se, MIN_NR_TASKS_DURING_FORCEIDLE))
13092 		resched_curr(rq);
13093 }
13094 
13095 /*
13096  * Consider any infeasible weight scenario. Take for instance two tasks,
13097  * each bound to their respective sibling, one with weight 1 and one with
13098  * weight 2. Then the lower weight task will run ahead of the higher weight
13099  * task without bound.
13100  *
13101  * This utterly destroys the concept of a shared time base.
13102  *
13103  * Remember; all this is about a proportionally fair scheduling, where each
13104  * tasks receives:
13105  *
13106  *              w_i
13107  *   dt_i = ---------- dt                                     (1)
13108  *          \Sum_j w_j
13109  *
13110  * which we do by tracking a virtual time, s_i:
13111  *
13112  *          1
13113  *   s_i = --- d[t]_i                                         (2)
13114  *         w_i
13115  *
13116  * Where d[t] is a delta of discrete time, while dt is an infinitesimal.
13117  * The immediate corollary is that the ideal schedule S, where (2) to use
13118  * an infinitesimal delta, is:
13119  *
13120  *           1
13121  *   S = ---------- dt                                        (3)
13122  *       \Sum_i w_i
13123  *
13124  * From which we can define the lag, or deviation from the ideal, as:
13125  *
13126  *   lag(i) = S - s_i                                         (4)
13127  *
13128  * And since the one and only purpose is to approximate S, we get that:
13129  *
13130  *   \Sum_i w_i lag(i) := 0                                   (5)
13131  *
13132  * If this were not so, we no longer converge to S, and we can no longer
13133  * claim our scheduler has any of the properties we derive from S. This is
13134  * exactly what you did above, you broke it!
13135  *
13136  *
13137  * Let's continue for a while though; to see if there is anything useful to
13138  * be learned. We can combine (1)-(3) or (4)-(5) and express S in s_i:
13139  *
13140  *       \Sum_i w_i s_i
13141  *   S = --------------                                       (6)
13142  *         \Sum_i w_i
13143  *
13144  * Which gives us a way to compute S, given our s_i. Now, if you've read
13145  * our code, you know that we do not in fact do this, the reason for this
13146  * is two-fold. Firstly, computing S in that way requires a 64bit division
13147  * for every time we'd use it (see 12), and secondly, this only describes
13148  * the steady-state, it doesn't handle dynamics.
13149  *
13150  * Anyway, in (6):  s_i -> x + (s_i - x), to get:
13151  *
13152  *           \Sum_i w_i (s_i - x)
13153  *   S - x = --------------------                             (7)
13154  *              \Sum_i w_i
13155  *
13156  * Which shows that S and s_i transform alike (which makes perfect sense
13157  * given that S is basically the (weighted) average of s_i).
13158  *
13159  * So the thing to remember is that the above is strictly UP. It is
13160  * possible to generalize to multiple runqueues -- however it gets really
13161  * yuck when you have to add affinity support, as illustrated by our very
13162  * first counter-example.
13163  *
13164  * Luckily I think we can avoid needing a full multi-queue variant for
13165  * core-scheduling (or load-balancing). The crucial observation is that we
13166  * only actually need this comparison in the presence of forced-idle; only
13167  * then do we need to tell if the stalled rq has higher priority over the
13168  * other.
13169  *
13170  * [XXX assumes SMT2; better consider the more general case, I suspect
13171  * it'll work out because our comparison is always between 2 rqs and the
13172  * answer is only interesting if one of them is forced-idle]
13173  *
13174  * And (under assumption of SMT2) when there is forced-idle, there is only
13175  * a single queue, so everything works like normal.
13176  *
13177  * Let, for our runqueue 'k':
13178  *
13179  *   T_k = \Sum_i w_i s_i
13180  *   W_k = \Sum_i w_i      ; for all i of k                  (8)
13181  *
13182  * Then we can write (6) like:
13183  *
13184  *         T_k
13185  *   S_k = ---                                               (9)
13186  *         W_k
13187  *
13188  * From which immediately follows that:
13189  *
13190  *           T_k + T_l
13191  *   S_k+l = ---------                                       (10)
13192  *           W_k + W_l
13193  *
13194  * On which we can define a combined lag:
13195  *
13196  *   lag_k+l(i) := S_k+l - s_i                               (11)
13197  *
13198  * And that gives us the tools to compare tasks across a combined runqueue.
13199  *
13200  *
13201  * Combined this gives the following:
13202  *
13203  *  a) when a runqueue enters force-idle, sync it against it's sibling rq(s)
13204  *     using (7); this only requires storing single 'time'-stamps.
13205  *
13206  *  b) when comparing tasks between 2 runqueues of which one is forced-idle,
13207  *     compare the combined lag, per (11).
13208  *
13209  * Now, of course cgroups (I so hate them) make this more interesting in
13210  * that a) seems to suggest we need to iterate all cgroup on a CPU at such
13211  * boundaries, but I think we can avoid that. The force-idle is for the
13212  * whole CPU, all it's rqs. So we can mark it in the root and lazily
13213  * propagate downward on demand.
13214  */
13215 
13216 /*
13217  * So this sync is basically a relative reset of S to 0.
13218  *
13219  * So with 2 queues, when one goes idle, we drop them both to 0 and one
13220  * then increases due to not being idle, and the idle one builds up lag to
13221  * get re-elected. So far so simple, right?
13222  *
13223  * When there's 3, we can have the situation where 2 run and one is idle,
13224  * we sync to 0 and let the idle one build up lag to get re-election. Now
13225  * suppose another one also drops idle. At this point dropping all to 0
13226  * again would destroy the built-up lag from the queue that was already
13227  * idle, not good.
13228  *
13229  * So instead of syncing everything, we can:
13230  *
13231  *   less := !((s64)(s_a - s_b) <= 0)
13232  *
13233  *   (v_a - S_a) - (v_b - S_b) == v_a - v_b - S_a + S_b
13234  *                             == v_a - (v_b - S_a + S_b)
13235  *
13236  * IOW, we can recast the (lag) comparison to a one-sided difference.
13237  * So if then, instead of syncing the whole queue, sync the idle queue
13238  * against the active queue with S_a + S_b at the point where we sync.
13239  *
13240  * (XXX consider the implication of living in a cyclic group: N / 2^n N)
13241  *
13242  * This gives us means of syncing single queues against the active queue,
13243  * and for already idle queues to preserve their build-up lag.
13244  *
13245  * Of course, then we get the situation where there's 2 active and one
13246  * going idle, who do we pick to sync against? Theory would have us sync
13247  * against the combined S, but as we've already demonstrated, there is no
13248  * such thing in infeasible weight scenarios.
13249  *
13250  * One thing I've considered; and this is where that core_active rudiment
13251  * came from, is having active queues sync up between themselves after
13252  * every tick. This limits the observed divergence due to the work
13253  * conservancy.
13254  *
13255  * On top of that, we can improve upon things by employing (10) here.
13256  */
13257 
13258 /*
13259  * se_fi_update - Update the cfs_rq->zero_vruntime_fi in a CFS hierarchy if needed.
13260  */
13261 static void se_fi_update(const struct sched_entity *se, unsigned int fi_seq,
13262 			 bool forceidle)
13263 {
13264 	for_each_sched_entity(se) {
13265 		struct cfs_rq *cfs_rq = cfs_rq_of(se);
13266 
13267 		if (forceidle) {
13268 			if (cfs_rq->forceidle_seq == fi_seq)
13269 				break;
13270 			cfs_rq->forceidle_seq = fi_seq;
13271 		}
13272 
13273 		cfs_rq->zero_vruntime_fi = cfs_rq->zero_vruntime;
13274 	}
13275 }
13276 
13277 void task_vruntime_update(struct rq *rq, struct task_struct *p, bool in_fi)
13278 {
13279 	struct sched_entity *se = &p->se;
13280 
13281 	if (p->sched_class != &fair_sched_class)
13282 		return;
13283 
13284 	se_fi_update(se, rq->core->core_forceidle_seq, in_fi);
13285 }
13286 
13287 bool cfs_prio_less(const struct task_struct *a, const struct task_struct *b,
13288 			bool in_fi)
13289 {
13290 	struct rq *rq = task_rq(a);
13291 	const struct sched_entity *sea = &a->se;
13292 	const struct sched_entity *seb = &b->se;
13293 	struct cfs_rq *cfs_rqa;
13294 	struct cfs_rq *cfs_rqb;
13295 	s64 delta;
13296 
13297 	WARN_ON_ONCE(task_rq(b)->core != rq->core);
13298 
13299 #ifdef CONFIG_FAIR_GROUP_SCHED
13300 	/*
13301 	 * Find an se in the hierarchy for tasks a and b, such that the se's
13302 	 * are immediate siblings.
13303 	 */
13304 	while (sea->cfs_rq->tg != seb->cfs_rq->tg) {
13305 		int sea_depth = sea->depth;
13306 		int seb_depth = seb->depth;
13307 
13308 		if (sea_depth >= seb_depth)
13309 			sea = parent_entity(sea);
13310 		if (sea_depth <= seb_depth)
13311 			seb = parent_entity(seb);
13312 	}
13313 
13314 	se_fi_update(sea, rq->core->core_forceidle_seq, in_fi);
13315 	se_fi_update(seb, rq->core->core_forceidle_seq, in_fi);
13316 
13317 	cfs_rqa = sea->cfs_rq;
13318 	cfs_rqb = seb->cfs_rq;
13319 #else /* !CONFIG_FAIR_GROUP_SCHED: */
13320 	cfs_rqa = &task_rq(a)->cfs;
13321 	cfs_rqb = &task_rq(b)->cfs;
13322 #endif /* !CONFIG_FAIR_GROUP_SCHED */
13323 
13324 	/*
13325 	 * Find delta after normalizing se's vruntime with its cfs_rq's
13326 	 * zero_vruntime_fi, which would have been updated in prior calls
13327 	 * to se_fi_update().
13328 	 */
13329 	delta = vruntime_op(sea->vruntime, "-", seb->vruntime) +
13330 		vruntime_op(cfs_rqb->zero_vruntime_fi, "-", cfs_rqa->zero_vruntime_fi);
13331 
13332 	return delta > 0;
13333 }
13334 
13335 static int task_is_throttled_fair(struct task_struct *p, int cpu)
13336 {
13337 	struct cfs_rq *cfs_rq;
13338 
13339 #ifdef CONFIG_FAIR_GROUP_SCHED
13340 	cfs_rq = task_group(p)->cfs_rq[cpu];
13341 #else
13342 	cfs_rq = &cpu_rq(cpu)->cfs;
13343 #endif
13344 	return throttled_hierarchy(cfs_rq);
13345 }
13346 #else /* !CONFIG_SCHED_CORE: */
13347 static inline void task_tick_core(struct rq *rq, struct task_struct *curr) {}
13348 #endif /* !CONFIG_SCHED_CORE */
13349 
13350 /*
13351  * scheduler tick hitting a task of our scheduling class.
13352  *
13353  * NOTE: This function can be called remotely by the tick offload that
13354  * goes along full dynticks. Therefore no local assumption can be made
13355  * and everything must be accessed through the @rq and @curr passed in
13356  * parameters.
13357  */
13358 static void task_tick_fair(struct rq *rq, struct task_struct *curr, int queued)
13359 {
13360 	struct cfs_rq *cfs_rq;
13361 	struct sched_entity *se = &curr->se;
13362 
13363 	for_each_sched_entity(se) {
13364 		cfs_rq = cfs_rq_of(se);
13365 		entity_tick(cfs_rq, se, queued);
13366 	}
13367 
13368 	if (queued) {
13369 		if (!need_resched())
13370 			hrtick_start_fair(rq, curr);
13371 		return;
13372 	}
13373 
13374 	if (static_branch_unlikely(&sched_numa_balancing))
13375 		task_tick_numa(rq, curr);
13376 
13377 	update_misfit_status(curr, rq);
13378 	check_update_overutilized_status(task_rq(curr));
13379 
13380 	task_tick_core(rq, curr);
13381 }
13382 
13383 /*
13384  * called on fork with the child task as argument from the parent's context
13385  *  - child not yet on the tasklist
13386  *  - preemption disabled
13387  */
13388 static void task_fork_fair(struct task_struct *p)
13389 {
13390 	set_task_max_allowed_capacity(p);
13391 }
13392 
13393 /*
13394  * Priority of the task has changed. Check to see if we preempt
13395  * the current task.
13396  */
13397 static void
13398 prio_changed_fair(struct rq *rq, struct task_struct *p, u64 oldprio)
13399 {
13400 	if (!task_on_rq_queued(p))
13401 		return;
13402 
13403 	if (p->prio == oldprio)
13404 		return;
13405 
13406 	if (rq->cfs.nr_queued == 1)
13407 		return;
13408 
13409 	/*
13410 	 * Reschedule if we are currently running on this runqueue and
13411 	 * our priority decreased, or if we are not currently running on
13412 	 * this runqueue and our priority is higher than the current's
13413 	 */
13414 	if (task_current_donor(rq, p)) {
13415 		if (p->prio > oldprio)
13416 			resched_curr(rq);
13417 	} else {
13418 		wakeup_preempt(rq, p, 0);
13419 	}
13420 }
13421 
13422 #ifdef CONFIG_FAIR_GROUP_SCHED
13423 /*
13424  * Propagate the changes of the sched_entity across the tg tree to make it
13425  * visible to the root
13426  */
13427 static void propagate_entity_cfs_rq(struct sched_entity *se)
13428 {
13429 	struct cfs_rq *cfs_rq = cfs_rq_of(se);
13430 
13431 	/*
13432 	 * If a task gets attached to this cfs_rq and before being queued,
13433 	 * it gets migrated to another CPU due to reasons like affinity
13434 	 * change, make sure this cfs_rq stays on leaf cfs_rq list to have
13435 	 * that removed load decayed or it can cause faireness problem.
13436 	 */
13437 	if (!cfs_rq_pelt_clock_throttled(cfs_rq))
13438 		list_add_leaf_cfs_rq(cfs_rq);
13439 
13440 	/* Start to propagate at parent */
13441 	se = se->parent;
13442 
13443 	for_each_sched_entity(se) {
13444 		cfs_rq = cfs_rq_of(se);
13445 
13446 		update_load_avg(cfs_rq, se, UPDATE_TG);
13447 
13448 		if (!cfs_rq_pelt_clock_throttled(cfs_rq))
13449 			list_add_leaf_cfs_rq(cfs_rq);
13450 	}
13451 
13452 	assert_list_leaf_cfs_rq(rq_of(cfs_rq));
13453 }
13454 #else /* !CONFIG_FAIR_GROUP_SCHED: */
13455 static void propagate_entity_cfs_rq(struct sched_entity *se) { }
13456 #endif /* !CONFIG_FAIR_GROUP_SCHED */
13457 
13458 static void detach_entity_cfs_rq(struct sched_entity *se)
13459 {
13460 	struct cfs_rq *cfs_rq = cfs_rq_of(se);
13461 
13462 	/*
13463 	 * In case the task sched_avg hasn't been attached:
13464 	 * - A forked task which hasn't been woken up by wake_up_new_task().
13465 	 * - A task which has been woken up by try_to_wake_up() but is
13466 	 *   waiting for actually being woken up by sched_ttwu_pending().
13467 	 */
13468 	if (!se->avg.last_update_time)
13469 		return;
13470 
13471 	/* Catch up with the cfs_rq and remove our load when we leave */
13472 	update_load_avg(cfs_rq, se, 0);
13473 	detach_entity_load_avg(cfs_rq, se);
13474 	update_tg_load_avg(cfs_rq);
13475 	propagate_entity_cfs_rq(se);
13476 }
13477 
13478 static void attach_entity_cfs_rq(struct sched_entity *se)
13479 {
13480 	struct cfs_rq *cfs_rq = cfs_rq_of(se);
13481 
13482 	/* Synchronize entity with its cfs_rq */
13483 	update_load_avg(cfs_rq, se, sched_feat(ATTACH_AGE_LOAD) ? 0 : SKIP_AGE_LOAD);
13484 	attach_entity_load_avg(cfs_rq, se);
13485 	update_tg_load_avg(cfs_rq);
13486 	propagate_entity_cfs_rq(se);
13487 }
13488 
13489 static void detach_task_cfs_rq(struct task_struct *p)
13490 {
13491 	struct sched_entity *se = &p->se;
13492 
13493 	detach_entity_cfs_rq(se);
13494 }
13495 
13496 static void attach_task_cfs_rq(struct task_struct *p)
13497 {
13498 	struct sched_entity *se = &p->se;
13499 
13500 	attach_entity_cfs_rq(se);
13501 }
13502 
13503 static void switching_from_fair(struct rq *rq, struct task_struct *p)
13504 {
13505 	if (p->se.sched_delayed)
13506 		dequeue_task(rq, p, DEQUEUE_SLEEP | DEQUEUE_DELAYED | DEQUEUE_NOCLOCK);
13507 }
13508 
13509 static void switched_from_fair(struct rq *rq, struct task_struct *p)
13510 {
13511 	detach_task_cfs_rq(p);
13512 }
13513 
13514 static void switched_to_fair(struct rq *rq, struct task_struct *p)
13515 {
13516 	WARN_ON_ONCE(p->se.sched_delayed);
13517 
13518 	attach_task_cfs_rq(p);
13519 
13520 	set_task_max_allowed_capacity(p);
13521 
13522 	if (task_on_rq_queued(p)) {
13523 		/*
13524 		 * We were most likely switched from sched_rt, so
13525 		 * kick off the schedule if running, otherwise just see
13526 		 * if we can still preempt the current task.
13527 		 */
13528 		if (task_current_donor(rq, p))
13529 			resched_curr(rq);
13530 		else
13531 			wakeup_preempt(rq, p, 0);
13532 	}
13533 }
13534 
13535 static void __set_next_task_fair(struct rq *rq, struct task_struct *p, bool first)
13536 {
13537 	struct sched_entity *se = &p->se;
13538 
13539 	if (task_on_rq_queued(p)) {
13540 		/*
13541 		 * Move the next running task to the front of the list, so our
13542 		 * cfs_tasks list becomes MRU one.
13543 		 */
13544 		list_move(&se->group_node, &rq->cfs_tasks);
13545 	}
13546 	if (!first)
13547 		return;
13548 
13549 	WARN_ON_ONCE(se->sched_delayed);
13550 
13551 	if (hrtick_enabled_fair(rq))
13552 		hrtick_start_fair(rq, p);
13553 
13554 	update_misfit_status(p, rq);
13555 	sched_fair_update_stop_tick(rq, p);
13556 }
13557 
13558 /*
13559  * Account for a task changing its policy or group.
13560  *
13561  * This routine is mostly called to set cfs_rq->curr field when a task
13562  * migrates between groups/classes.
13563  */
13564 static void set_next_task_fair(struct rq *rq, struct task_struct *p, bool first)
13565 {
13566 	struct sched_entity *se = &p->se;
13567 
13568 	for_each_sched_entity(se) {
13569 		struct cfs_rq *cfs_rq = cfs_rq_of(se);
13570 
13571 		set_next_entity(cfs_rq, se);
13572 		/* ensure bandwidth has been allocated on our new cfs_rq */
13573 		account_cfs_rq_runtime(cfs_rq, 0);
13574 	}
13575 
13576 	__set_next_task_fair(rq, p, first);
13577 }
13578 
13579 void init_cfs_rq(struct cfs_rq *cfs_rq)
13580 {
13581 	cfs_rq->tasks_timeline = RB_ROOT_CACHED;
13582 	cfs_rq->zero_vruntime = (u64)(-(1LL << 20));
13583 	raw_spin_lock_init(&cfs_rq->removed.lock);
13584 }
13585 
13586 #ifdef CONFIG_FAIR_GROUP_SCHED
13587 static void task_change_group_fair(struct task_struct *p)
13588 {
13589 	/*
13590 	 * We couldn't detach or attach a forked task which
13591 	 * hasn't been woken up by wake_up_new_task().
13592 	 */
13593 	if (READ_ONCE(p->__state) == TASK_NEW)
13594 		return;
13595 
13596 	detach_task_cfs_rq(p);
13597 
13598 	/* Tell se's cfs_rq has been changed -- migrated */
13599 	p->se.avg.last_update_time = 0;
13600 	set_task_rq(p, task_cpu(p));
13601 	attach_task_cfs_rq(p);
13602 }
13603 
13604 void free_fair_sched_group(struct task_group *tg)
13605 {
13606 	int i;
13607 
13608 	for_each_possible_cpu(i) {
13609 		if (tg->cfs_rq)
13610 			kfree(tg->cfs_rq[i]);
13611 		if (tg->se)
13612 			kfree(tg->se[i]);
13613 	}
13614 
13615 	kfree(tg->cfs_rq);
13616 	kfree(tg->se);
13617 }
13618 
13619 int alloc_fair_sched_group(struct task_group *tg, struct task_group *parent)
13620 {
13621 	struct sched_entity *se;
13622 	struct cfs_rq *cfs_rq;
13623 	int i;
13624 
13625 	tg->cfs_rq = kcalloc(nr_cpu_ids, sizeof(cfs_rq), GFP_KERNEL);
13626 	if (!tg->cfs_rq)
13627 		goto err;
13628 	tg->se = kcalloc(nr_cpu_ids, sizeof(se), GFP_KERNEL);
13629 	if (!tg->se)
13630 		goto err;
13631 
13632 	tg->shares = NICE_0_LOAD;
13633 
13634 	init_cfs_bandwidth(tg_cfs_bandwidth(tg), tg_cfs_bandwidth(parent));
13635 
13636 	for_each_possible_cpu(i) {
13637 		cfs_rq = kzalloc_node(sizeof(struct cfs_rq),
13638 				      GFP_KERNEL, cpu_to_node(i));
13639 		if (!cfs_rq)
13640 			goto err;
13641 
13642 		se = kzalloc_node(sizeof(struct sched_entity_stats),
13643 				  GFP_KERNEL, cpu_to_node(i));
13644 		if (!se)
13645 			goto err_free_rq;
13646 
13647 		init_cfs_rq(cfs_rq);
13648 		init_tg_cfs_entry(tg, cfs_rq, se, i, parent->se[i]);
13649 		init_entity_runnable_average(se);
13650 	}
13651 
13652 	return 1;
13653 
13654 err_free_rq:
13655 	kfree(cfs_rq);
13656 err:
13657 	return 0;
13658 }
13659 
13660 void online_fair_sched_group(struct task_group *tg)
13661 {
13662 	struct sched_entity *se;
13663 	struct rq_flags rf;
13664 	struct rq *rq;
13665 	int i;
13666 
13667 	for_each_possible_cpu(i) {
13668 		rq = cpu_rq(i);
13669 		se = tg->se[i];
13670 		rq_lock_irq(rq, &rf);
13671 		update_rq_clock(rq);
13672 		attach_entity_cfs_rq(se);
13673 		sync_throttle(tg, i);
13674 		rq_unlock_irq(rq, &rf);
13675 	}
13676 }
13677 
13678 void unregister_fair_sched_group(struct task_group *tg)
13679 {
13680 	int cpu;
13681 
13682 	destroy_cfs_bandwidth(tg_cfs_bandwidth(tg));
13683 
13684 	for_each_possible_cpu(cpu) {
13685 		struct cfs_rq *cfs_rq = tg->cfs_rq[cpu];
13686 		struct sched_entity *se = tg->se[cpu];
13687 		struct rq *rq = cpu_rq(cpu);
13688 
13689 		if (se) {
13690 			if (se->sched_delayed) {
13691 				guard(rq_lock_irqsave)(rq);
13692 				if (se->sched_delayed) {
13693 					update_rq_clock(rq);
13694 					dequeue_entities(rq, se, DEQUEUE_SLEEP | DEQUEUE_DELAYED);
13695 				}
13696 				list_del_leaf_cfs_rq(cfs_rq);
13697 			}
13698 			remove_entity_load_avg(se);
13699 		}
13700 
13701 		/*
13702 		 * Only empty task groups can be destroyed; so we can speculatively
13703 		 * check on_list without danger of it being re-added.
13704 		 */
13705 		if (cfs_rq->on_list) {
13706 			guard(rq_lock_irqsave)(rq);
13707 			list_del_leaf_cfs_rq(cfs_rq);
13708 		}
13709 	}
13710 }
13711 
13712 void init_tg_cfs_entry(struct task_group *tg, struct cfs_rq *cfs_rq,
13713 			struct sched_entity *se, int cpu,
13714 			struct sched_entity *parent)
13715 {
13716 	struct rq *rq = cpu_rq(cpu);
13717 
13718 	cfs_rq->tg = tg;
13719 	cfs_rq->rq = rq;
13720 	init_cfs_rq_runtime(cfs_rq);
13721 
13722 	tg->cfs_rq[cpu] = cfs_rq;
13723 	tg->se[cpu] = se;
13724 
13725 	/* se could be NULL for root_task_group */
13726 	if (!se)
13727 		return;
13728 
13729 	if (!parent) {
13730 		se->cfs_rq = &rq->cfs;
13731 		se->depth = 0;
13732 	} else {
13733 		se->cfs_rq = parent->my_q;
13734 		se->depth = parent->depth + 1;
13735 	}
13736 
13737 	se->my_q = cfs_rq;
13738 	/* guarantee group entities always have weight */
13739 	update_load_set(&se->load, NICE_0_LOAD);
13740 	se->parent = parent;
13741 }
13742 
13743 static DEFINE_MUTEX(shares_mutex);
13744 
13745 static int __sched_group_set_shares(struct task_group *tg, unsigned long shares)
13746 {
13747 	int i;
13748 
13749 	lockdep_assert_held(&shares_mutex);
13750 
13751 	/*
13752 	 * We can't change the weight of the root cgroup.
13753 	 */
13754 	if (!tg->se[0])
13755 		return -EINVAL;
13756 
13757 	shares = clamp(shares, scale_load(MIN_SHARES), scale_load(MAX_SHARES));
13758 
13759 	if (tg->shares == shares)
13760 		return 0;
13761 
13762 	tg->shares = shares;
13763 	for_each_possible_cpu(i) {
13764 		struct rq *rq = cpu_rq(i);
13765 		struct sched_entity *se = tg->se[i];
13766 		struct rq_flags rf;
13767 
13768 		/* Propagate contribution to hierarchy */
13769 		rq_lock_irqsave(rq, &rf);
13770 		update_rq_clock(rq);
13771 		for_each_sched_entity(se) {
13772 			update_load_avg(cfs_rq_of(se), se, UPDATE_TG);
13773 			update_cfs_group(se);
13774 		}
13775 		rq_unlock_irqrestore(rq, &rf);
13776 	}
13777 
13778 	return 0;
13779 }
13780 
13781 int sched_group_set_shares(struct task_group *tg, unsigned long shares)
13782 {
13783 	int ret;
13784 
13785 	mutex_lock(&shares_mutex);
13786 	if (tg_is_idle(tg))
13787 		ret = -EINVAL;
13788 	else
13789 		ret = __sched_group_set_shares(tg, shares);
13790 	mutex_unlock(&shares_mutex);
13791 
13792 	return ret;
13793 }
13794 
13795 int sched_group_set_idle(struct task_group *tg, long idle)
13796 {
13797 	int i;
13798 
13799 	if (tg == &root_task_group)
13800 		return -EINVAL;
13801 
13802 	if (idle < 0 || idle > 1)
13803 		return -EINVAL;
13804 
13805 	mutex_lock(&shares_mutex);
13806 
13807 	if (tg->idle == idle) {
13808 		mutex_unlock(&shares_mutex);
13809 		return 0;
13810 	}
13811 
13812 	tg->idle = idle;
13813 
13814 	for_each_possible_cpu(i) {
13815 		struct rq *rq = cpu_rq(i);
13816 		struct sched_entity *se = tg->se[i];
13817 		struct cfs_rq *grp_cfs_rq = tg->cfs_rq[i];
13818 		bool was_idle = cfs_rq_is_idle(grp_cfs_rq);
13819 		long idle_task_delta;
13820 		struct rq_flags rf;
13821 
13822 		rq_lock_irqsave(rq, &rf);
13823 
13824 		grp_cfs_rq->idle = idle;
13825 		if (WARN_ON_ONCE(was_idle == cfs_rq_is_idle(grp_cfs_rq)))
13826 			goto next_cpu;
13827 
13828 		idle_task_delta = grp_cfs_rq->h_nr_queued -
13829 				  grp_cfs_rq->h_nr_idle;
13830 		if (!cfs_rq_is_idle(grp_cfs_rq))
13831 			idle_task_delta *= -1;
13832 
13833 		for_each_sched_entity(se) {
13834 			struct cfs_rq *cfs_rq = cfs_rq_of(se);
13835 
13836 			if (!se->on_rq)
13837 				break;
13838 
13839 			cfs_rq->h_nr_idle += idle_task_delta;
13840 
13841 			/* Already accounted at parent level and above. */
13842 			if (cfs_rq_is_idle(cfs_rq))
13843 				break;
13844 		}
13845 
13846 next_cpu:
13847 		rq_unlock_irqrestore(rq, &rf);
13848 	}
13849 
13850 	/* Idle groups have minimum weight. */
13851 	if (tg_is_idle(tg))
13852 		__sched_group_set_shares(tg, scale_load(WEIGHT_IDLEPRIO));
13853 	else
13854 		__sched_group_set_shares(tg, NICE_0_LOAD);
13855 
13856 	mutex_unlock(&shares_mutex);
13857 	return 0;
13858 }
13859 
13860 #endif /* CONFIG_FAIR_GROUP_SCHED */
13861 
13862 
13863 static unsigned int get_rr_interval_fair(struct rq *rq, struct task_struct *task)
13864 {
13865 	struct sched_entity *se = &task->se;
13866 	unsigned int rr_interval = 0;
13867 
13868 	/*
13869 	 * Time slice is 0 for SCHED_OTHER tasks that are on an otherwise
13870 	 * idle runqueue:
13871 	 */
13872 	if (rq->cfs.load.weight)
13873 		rr_interval = NS_TO_JIFFIES(se->slice);
13874 
13875 	return rr_interval;
13876 }
13877 
13878 /*
13879  * All the scheduling class methods:
13880  */
13881 DEFINE_SCHED_CLASS(fair) = {
13882 	.enqueue_task		= enqueue_task_fair,
13883 	.dequeue_task		= dequeue_task_fair,
13884 	.yield_task		= yield_task_fair,
13885 	.yield_to_task		= yield_to_task_fair,
13886 
13887 	.wakeup_preempt		= wakeup_preempt_fair,
13888 
13889 	.pick_task		= pick_task_fair,
13890 	.pick_next_task		= pick_next_task_fair,
13891 	.put_prev_task		= put_prev_task_fair,
13892 	.set_next_task          = set_next_task_fair,
13893 
13894 	.select_task_rq		= select_task_rq_fair,
13895 	.migrate_task_rq	= migrate_task_rq_fair,
13896 
13897 	.rq_online		= rq_online_fair,
13898 	.rq_offline		= rq_offline_fair,
13899 
13900 	.task_dead		= task_dead_fair,
13901 	.set_cpus_allowed	= set_cpus_allowed_fair,
13902 
13903 	.task_tick		= task_tick_fair,
13904 	.task_fork		= task_fork_fair,
13905 
13906 	.reweight_task		= reweight_task_fair,
13907 	.prio_changed		= prio_changed_fair,
13908 	.switching_from		= switching_from_fair,
13909 	.switched_from		= switched_from_fair,
13910 	.switched_to		= switched_to_fair,
13911 
13912 	.get_rr_interval	= get_rr_interval_fair,
13913 
13914 	.update_curr		= update_curr_fair,
13915 
13916 #ifdef CONFIG_FAIR_GROUP_SCHED
13917 	.task_change_group	= task_change_group_fair,
13918 #endif
13919 
13920 #ifdef CONFIG_SCHED_CORE
13921 	.task_is_throttled	= task_is_throttled_fair,
13922 #endif
13923 
13924 #ifdef CONFIG_UCLAMP_TASK
13925 	.uclamp_enabled		= 1,
13926 #endif
13927 };
13928 
13929 void print_cfs_stats(struct seq_file *m, int cpu)
13930 {
13931 	struct cfs_rq *cfs_rq, *pos;
13932 
13933 	rcu_read_lock();
13934 	for_each_leaf_cfs_rq_safe(cpu_rq(cpu), cfs_rq, pos)
13935 		print_cfs_rq(m, cpu, cfs_rq);
13936 	rcu_read_unlock();
13937 }
13938 
13939 #ifdef CONFIG_NUMA_BALANCING
13940 void show_numa_stats(struct task_struct *p, struct seq_file *m)
13941 {
13942 	int node;
13943 	unsigned long tsf = 0, tpf = 0, gsf = 0, gpf = 0;
13944 	struct numa_group *ng;
13945 
13946 	rcu_read_lock();
13947 	ng = rcu_dereference_all(p->numa_group);
13948 	for_each_online_node(node) {
13949 		if (p->numa_faults) {
13950 			tsf = p->numa_faults[task_faults_idx(NUMA_MEM, node, 0)];
13951 			tpf = p->numa_faults[task_faults_idx(NUMA_MEM, node, 1)];
13952 		}
13953 		if (ng) {
13954 			gsf = ng->faults[task_faults_idx(NUMA_MEM, node, 0)],
13955 			gpf = ng->faults[task_faults_idx(NUMA_MEM, node, 1)];
13956 		}
13957 		print_numa_stats(m, node, tsf, tpf, gsf, gpf);
13958 	}
13959 	rcu_read_unlock();
13960 }
13961 #endif /* CONFIG_NUMA_BALANCING */
13962 
13963 __init void init_sched_fair_class(void)
13964 {
13965 	int i;
13966 
13967 	for_each_possible_cpu(i) {
13968 		zalloc_cpumask_var_node(&per_cpu(load_balance_mask, i), GFP_KERNEL, cpu_to_node(i));
13969 		zalloc_cpumask_var_node(&per_cpu(select_rq_mask,    i), GFP_KERNEL, cpu_to_node(i));
13970 		zalloc_cpumask_var_node(&per_cpu(should_we_balance_tmpmask, i),
13971 					GFP_KERNEL, cpu_to_node(i));
13972 
13973 #ifdef CONFIG_CFS_BANDWIDTH
13974 		INIT_CSD(&cpu_rq(i)->cfsb_csd, __cfsb_csd_unthrottle, cpu_rq(i));
13975 		INIT_LIST_HEAD(&cpu_rq(i)->cfsb_csd_list);
13976 #endif
13977 	}
13978 
13979 	open_softirq(SCHED_SOFTIRQ, sched_balance_softirq);
13980 
13981 #ifdef CONFIG_NO_HZ_COMMON
13982 	nohz.next_balance = jiffies;
13983 	nohz.next_blocked = jiffies;
13984 	zalloc_cpumask_var(&nohz.idle_cpus_mask, GFP_NOWAIT);
13985 #endif
13986 }
13987