1 /*-
2 * SPDX-License-Identifier: BSD-3-Clause
3 *
4 * Copyright (c) 1982, 1986, 1990, 1991, 1993
5 * The Regents of the University of California. All rights reserved.
6 * (c) UNIX System Laboratories, Inc.
7 * All or some portions of this file are derived from material licensed
8 * to the University of California by American Telephone and Telegraph
9 * Co. or Unix System Laboratories, Inc. and are reproduced herein with
10 * the permission of UNIX System Laboratories, Inc.
11 *
12 * Redistribution and use in source and binary forms, with or without
13 * modification, are permitted provided that the following conditions
14 * are met:
15 * 1. Redistributions of source code must retain the above copyright
16 * notice, this list of conditions and the following disclaimer.
17 * 2. Redistributions in binary form must reproduce the above copyright
18 * notice, this list of conditions and the following disclaimer in the
19 * documentation and/or other materials provided with the distribution.
20 * 3. Neither the name of the University nor the names of its contributors
21 * may be used to endorse or promote products derived from this software
22 * without specific prior written permission.
23 *
24 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
25 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
26 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
27 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
28 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
29 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
30 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
31 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
32 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
33 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
34 * SUCH DAMAGE.
35 */
36
37 #include "opt_hwpmc_hooks.h"
38 #include "opt_hwt_hooks.h"
39 #include "opt_sched.h"
40
41 #include <sys/systm.h>
42 #include <sys/cpuset.h>
43 #include <sys/kernel.h>
44 #include <sys/ktr.h>
45 #include <sys/lock.h>
46 #include <sys/kthread.h>
47 #include <sys/mutex.h>
48 #include <sys/proc.h>
49 #include <sys/resourcevar.h>
50 #include <sys/runq.h>
51 #include <sys/sched.h>
52 #include <sys/sdt.h>
53 #include <sys/smp.h>
54 #include <sys/sysctl.h>
55 #include <sys/sx.h>
56 #include <sys/turnstile.h>
57 #include <sys/umtxvar.h>
58 #include <machine/pcb.h>
59 #include <machine/smp.h>
60
61 #ifdef HWPMC_HOOKS
62 #include <sys/pmckern.h>
63 #endif
64
65 #ifdef HWT_HOOKS
66 #include <dev/hwt/hwt_hook.h>
67 #endif
68
69 /*
70 * INVERSE_ESTCPU_WEIGHT is only suitable for statclock() frequencies in
71 * the range 100-256 Hz (approximately).
72 */
73 #define INVERSE_ESTCPU_WEIGHT 8 /* 1 / (priorities per estcpu level). */
74 #define NICE_WEIGHT 1 /* Priorities per nice level. */
75 #define ESTCPULIM(e) \
76 min((e), INVERSE_ESTCPU_WEIGHT * \
77 (PRI_MAX_TIMESHARE - PRI_MIN_TIMESHARE - \
78 (PRIO_MAX - PRIO_MIN) * NICE_WEIGHT) \
79 + INVERSE_ESTCPU_WEIGHT - 1)
80
81 #define TS_NAME_LEN (MAXCOMLEN + sizeof(" td ") + sizeof(__XSTRING(UINT_MAX)))
82
83 /*
84 * The schedulable entity that runs a context.
85 * This is an extension to the thread structure and is tailored to
86 * the requirements of this scheduler.
87 * All fields are protected by the scheduler lock.
88 */
89 struct td_sched {
90 fixpt_t ts_pctcpu; /* %cpu during p_swtime. */
91 u_int ts_estcpu; /* Estimated cpu utilization. */
92 int ts_cpticks; /* Ticks of cpu time. */
93 int ts_slptime; /* Seconds !RUNNING. */
94 int ts_slice; /* Remaining part of time slice. */
95 int ts_flags;
96 int ts_rqcpu; /* That CPU's runq or NOCPU => global */
97 #ifdef KTR
98 char ts_name[TS_NAME_LEN];
99 #endif
100 };
101
102 /* flags kept in td_flags */
103 #define TDF_DIDRUN TDF_SCHED0 /* thread actually ran. */
104 #define TDF_BOUND TDF_SCHED1 /* Bound to one CPU. */
105 #define TDF_SLICEEND TDF_SCHED2 /* Thread time slice is over. */
106
107 #define TDP_RESCHED TDP_SCHED1 /* Reschedule due to maybe_resched(). */
108
109 /* flags kept in ts_flags */
110 #define TSF_AFFINITY 0x0001 /* Has a non-"full" CPU set. */
111
112 #ifdef SMP
113 #define TS_RUNQ_PTR(ts) ((ts)->ts_rqcpu == NOCPU ? \
114 (&runq_global) : (DPCPU_ID_PTR((ts)->ts_rqcpu, runq_pcpu)))
115 #else
116 #define TS_RUNQ_PTR(ts) (&runq_global)
117 #endif
118
119 #define THREAD_CAN_SCHED(td, cpu) \
120 CPU_ISSET((cpu), &(td)->td_cpuset->cs_mask)
121
122 _Static_assert(sizeof(struct thread) + sizeof(struct td_sched) <=
123 sizeof(struct thread0_storage),
124 "increase struct thread0_storage.t0st_sched size");
125
126 static struct mtx sched_lock;
127
128 static int realstathz = 127; /* stathz is sometimes 0 and run off of hz. */
129 static int sched_tdcnt; /* Total runnable threads in the system. */
130 static int sched_slice = 12; /* Thread run time before rescheduling. */
131
132 static void setup_runqs(void);
133 static void schedcpu(void);
134 static void schedcpu_thread(void);
135 static void sched_priority(struct thread *td, u_char prio);
136 static void maybe_resched(struct thread *td);
137 static void updatepri(struct thread *td);
138 static void resetpriority(struct thread *td);
139 static void resetpriority_thread(struct thread *td);
140 #ifdef SMP
141 static int sched_pickcpu(struct thread *td);
142 static int forward_wakeup(int cpunum);
143 static void kick_other_cpu(int pri, int cpuid);
144 #endif
145
146 static struct kproc_desc sched_kp = {
147 "schedcpu",
148 schedcpu_thread,
149 NULL
150 };
151
152 static void
sched_4bsd_schedcpu(void)153 sched_4bsd_schedcpu(void)
154 {
155 kproc_start(&sched_kp);
156 }
157
158 /*
159 * Global run queue.
160 */
161 static struct runq runq_global;
162
163 #ifdef SMP
164 /*
165 * Per-CPU run queues
166 */
167 DPCPU_DEFINE_STATIC(struct runq, runq_pcpu);
168 DPCPU_DEFINE_STATIC(long, runq_length);
169
170 static cpuset_t idle_cpus_mask;
171 #endif
172
173 struct pcpuidlestat {
174 u_int idlecalls;
175 u_int oldidlecalls;
176 };
177 DPCPU_DEFINE_STATIC(struct pcpuidlestat, idlestat);
178
179 static void
setup_runqs(void)180 setup_runqs(void)
181 {
182 #ifdef SMP
183 int cpu;
184
185 CPU_FOREACH(cpu)
186 runq_init(DPCPU_ID_PTR(cpu, runq_pcpu));
187 #endif
188
189 runq_init(&runq_global);
190 }
191
192 static int
sysctl_kern_4bsd_quantum(SYSCTL_HANDLER_ARGS)193 sysctl_kern_4bsd_quantum(SYSCTL_HANDLER_ARGS)
194 {
195 int error, new_val, period;
196
197 period = 1000000 / realstathz;
198 new_val = period * sched_slice;
199 error = sysctl_handle_int(oidp, &new_val, 0, req);
200 if (error != 0 || req->newptr == NULL)
201 return (error);
202 if (new_val <= 0)
203 return (EINVAL);
204 sched_slice = imax(1, (new_val + period / 2) / period);
205 hogticks = imax(1, (2 * hz * sched_slice + realstathz / 2) /
206 realstathz);
207 return (0);
208 }
209
210 SYSCTL_NODE(_kern_sched, OID_AUTO, 4bsd, CTLFLAG_RD | CTLFLAG_MPSAFE, 0,
211 "4BSD Scheduler");
212
213 SYSCTL_PROC(_kern_sched_4bsd, OID_AUTO, quantum,
214 CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_MPSAFE, NULL, 0,
215 sysctl_kern_4bsd_quantum, "I",
216 "Quantum for timeshare threads in microseconds");
217 SYSCTL_INT(_kern_sched_4bsd, OID_AUTO, slice, CTLFLAG_RW, &sched_slice, 0,
218 "Quantum for timeshare threads in stathz ticks");
219 #ifdef SMP
220 /* Enable forwarding of wakeups to all other cpus */
221 static SYSCTL_NODE(_kern_sched_4bsd, OID_AUTO, ipiwakeup,
222 CTLFLAG_RD | CTLFLAG_MPSAFE, NULL,
223 "Kernel SMP");
224
225 static int runq_fuzz = 1;
226 SYSCTL_INT(_kern_sched_4bsd, OID_AUTO, runq_fuzz, CTLFLAG_RW,
227 &runq_fuzz, 0, "");
228
229 static int forward_wakeup_enabled = 1;
230 SYSCTL_INT(_kern_sched_4bsd_ipiwakeup, OID_AUTO, enabled, CTLFLAG_RW,
231 &forward_wakeup_enabled, 0,
232 "Forwarding of wakeup to idle CPUs");
233
234 static int forward_wakeups_requested = 0;
235 SYSCTL_INT(_kern_sched_4bsd_ipiwakeup, OID_AUTO, requested, CTLFLAG_RD,
236 &forward_wakeups_requested, 0,
237 "Requests for Forwarding of wakeup to idle CPUs");
238
239 static int forward_wakeups_delivered = 0;
240 SYSCTL_INT(_kern_sched_4bsd_ipiwakeup, OID_AUTO, delivered, CTLFLAG_RD,
241 &forward_wakeups_delivered, 0,
242 "Completed Forwarding of wakeup to idle CPUs");
243
244 static int forward_wakeup_use_mask = 1;
245 SYSCTL_INT(_kern_sched_4bsd_ipiwakeup, OID_AUTO, usemask, CTLFLAG_RW,
246 &forward_wakeup_use_mask, 0,
247 "Use the mask of idle cpus");
248
249 static int forward_wakeup_use_loop = 0;
250 SYSCTL_INT(_kern_sched_4bsd_ipiwakeup, OID_AUTO, useloop, CTLFLAG_RW,
251 &forward_wakeup_use_loop, 0,
252 "Use a loop to find idle cpus");
253
254 #endif
255 #if 0
256 static int sched_followon = 0;
257 SYSCTL_INT(_kern_sched_4bsd, OID_AUTO, followon, CTLFLAG_RW,
258 &sched_followon, 0,
259 "allow threads to share a quantum");
260 #endif
261
262 static __inline void
sched_load_add(void)263 sched_load_add(void)
264 {
265
266 sched_tdcnt++;
267 KTR_COUNTER0(KTR_SCHED, "load", "global load", sched_tdcnt);
268 SDT_PROBE2(sched, , , load__change, NOCPU, sched_tdcnt);
269 }
270
271 static __inline void
sched_load_rem(void)272 sched_load_rem(void)
273 {
274
275 sched_tdcnt--;
276 KTR_COUNTER0(KTR_SCHED, "load", "global load", sched_tdcnt);
277 SDT_PROBE2(sched, , , load__change, NOCPU, sched_tdcnt);
278 }
279
280 static void
maybe_resched_ast(struct thread * td,int tda)281 maybe_resched_ast(struct thread *td, int tda)
282 {
283 MPASS(td == curthread); /* We are AST */
284 if ((td->td_pflags & TDP_RESCHED) != 0) {
285 td->td_pflags &= ~TDP_RESCHED;
286 ast_scheduler(td, tda);
287 }
288 }
289
290 /*
291 * Arrange to reschedule if necessary, taking the priorities and
292 * schedulers into account.
293 */
294 static void
maybe_resched(struct thread * td)295 maybe_resched(struct thread *td)
296 {
297 struct thread *ctd;
298
299 ctd = curthread;
300 THREAD_LOCK_ASSERT(td, MA_OWNED);
301 if (td->td_priority < ctd->td_priority)
302 ctd->td_pflags |= TDP_RESCHED;
303 }
304
305 /*
306 * This function is called when a thread is about to be put on run queue
307 * because it has been made runnable or its priority has been adjusted. It
308 * determines if the new thread should preempt the current thread. If so,
309 * it sets td_owepreempt to request a preemption.
310 */
311 static int
maybe_preempt(struct thread * td)312 maybe_preempt(struct thread *td)
313 {
314 #ifdef PREEMPTION
315 struct thread *ctd;
316 int cpri, pri;
317
318 /*
319 * The new thread should not preempt the current thread if any of the
320 * following conditions are true:
321 *
322 * - The kernel is in the throes of crashing (panicstr).
323 * - The current thread has a higher (numerically lower) or
324 * equivalent priority. Note that this prevents curthread from
325 * trying to preempt to itself.
326 * - The current thread has an inhibitor set or is in the process of
327 * exiting. In this case, the current thread is about to switch
328 * out anyways, so there's no point in preempting. If we did,
329 * the current thread would not be properly resumed as well, so
330 * just avoid that whole landmine.
331 * - If the new thread's priority is not a realtime priority and
332 * the current thread's priority is not an idle priority and
333 * FULL_PREEMPTION is disabled.
334 *
335 * If all of these conditions are false, but the current thread is in
336 * a nested critical section, then we have to defer the preemption
337 * until we exit the critical section. Otherwise, switch immediately
338 * to the new thread.
339 */
340 ctd = curthread;
341 THREAD_LOCK_ASSERT(td, MA_OWNED);
342 KASSERT((td->td_inhibitors == 0),
343 ("maybe_preempt: trying to run inhibited thread"));
344 pri = td->td_priority;
345 cpri = ctd->td_priority;
346 if (KERNEL_PANICKED() || pri >= cpri /* || dumping */ ||
347 TD_IS_INHIBITED(ctd))
348 return (0);
349 #ifndef FULL_PREEMPTION
350 if (pri > PRI_MAX_ITHD && cpri < PRI_MIN_IDLE)
351 return (0);
352 #endif
353
354 CTR0(KTR_PROC, "maybe_preempt: scheduling preemption");
355 ctd->td_owepreempt = 1;
356 return (1);
357 #else
358 return (0);
359 #endif
360 }
361
362 /*
363 * Constants for digital decay and forget:
364 * 90% of (ts_estcpu) usage in 5 * loadav time
365 * 95% of (ts_pctcpu) usage in 60 seconds (load insensitive)
366 * Note that, as ps(1) mentions, this can let percentages
367 * total over 100% (I've seen 137.9% for 3 processes).
368 *
369 * Note that schedclock() updates ts_estcpu and p_cpticks asynchronously.
370 *
371 * We wish to decay away 90% of ts_estcpu in (5 * loadavg) seconds.
372 * That is, the system wants to compute a value of decay such
373 * that the following for loop:
374 * for (i = 0; i < (5 * loadavg); i++)
375 * ts_estcpu *= decay;
376 * will compute
377 * ts_estcpu *= 0.1;
378 * for all values of loadavg:
379 *
380 * Mathematically this loop can be expressed by saying:
381 * decay ** (5 * loadavg) ~= .1
382 *
383 * The system computes decay as:
384 * decay = (2 * loadavg) / (2 * loadavg + 1)
385 *
386 * We wish to prove that the system's computation of decay
387 * will always fulfill the equation:
388 * decay ** (5 * loadavg) ~= .1
389 *
390 * If we compute b as:
391 * b = 2 * loadavg
392 * then
393 * decay = b / (b + 1)
394 *
395 * We now need to prove two things:
396 * 1) Given factor ** (5 * loadavg) ~= .1, prove factor == b/(b+1)
397 * 2) Given b/(b+1) ** power ~= .1, prove power == (5 * loadavg)
398 *
399 * Facts:
400 * For x close to zero, exp(x) =~ 1 + x, since
401 * exp(x) = 0! + x**1/1! + x**2/2! + ... .
402 * therefore exp(-1/b) =~ 1 - (1/b) = (b-1)/b.
403 * For x close to zero, ln(1+x) =~ x, since
404 * ln(1+x) = x - x**2/2 + x**3/3 - ... -1 < x < 1
405 * therefore ln(b/(b+1)) = ln(1 - 1/(b+1)) =~ -1/(b+1).
406 * ln(.1) =~ -2.30
407 *
408 * Proof of (1):
409 * Solve (factor)**(power) =~ .1 given power (5*loadav):
410 * solving for factor,
411 * ln(factor) =~ (-2.30/5*loadav), or
412 * factor =~ exp(-1/((5/2.30)*loadav)) =~ exp(-1/(2*loadav)) =
413 * exp(-1/b) =~ (b-1)/b =~ b/(b+1). QED
414 *
415 * Proof of (2):
416 * Solve (factor)**(power) =~ .1 given factor == (b/(b+1)):
417 * solving for power,
418 * power*ln(b/(b+1)) =~ -2.30, or
419 * power =~ 2.3 * (b + 1) = 4.6*loadav + 2.3 =~ 5*loadav. QED
420 *
421 * Actual power values for the implemented algorithm are as follows:
422 * loadav: 1 2 3 4
423 * power: 5.68 10.32 14.94 19.55
424 */
425
426 /* calculations for digital decay to forget 90% of usage in 5*loadav sec */
427 #define loadfactor(loadav) (2 * (loadav))
428 #define decay_cpu(loadfac, cpu) (((loadfac) * (cpu)) / ((loadfac) + FSCALE))
429
430 extern fixpt_t ccpu;
431
432 /*
433 * If `ccpu' is not equal to `exp(-1/20)' and you still want to use the
434 * faster/more-accurate formula, you'll have to estimate CCPU_SHIFT below
435 * and possibly adjust FSHIFT in "param.h" so that (FSHIFT >= CCPU_SHIFT).
436 *
437 * To estimate CCPU_SHIFT for exp(-1/20), the following formula was used:
438 * 1 - exp(-1/20) ~= 0.0487 ~= 0.0488 == 1 (fixed pt, *11* bits).
439 *
440 * If you don't want to bother with the faster/more-accurate formula, you
441 * can set CCPU_SHIFT to (FSHIFT + 1) which will use a slower/less-accurate
442 * (more general) method of calculating the %age of CPU used by a process.
443 */
444 #define CCPU_SHIFT 11
445
446 /*
447 * Recompute process priorities, every hz ticks.
448 * MP-safe, called without the Giant mutex.
449 */
450 /* ARGSUSED */
451 static void
schedcpu(void)452 schedcpu(void)
453 {
454 fixpt_t loadfac = loadfactor(averunnable.ldavg[0]);
455 struct thread *td;
456 struct proc *p;
457 struct td_sched *ts;
458 int awake;
459
460 sx_slock(&allproc_lock);
461 FOREACH_PROC_IN_SYSTEM(p) {
462 PROC_LOCK(p);
463 if (p->p_state == PRS_NEW) {
464 PROC_UNLOCK(p);
465 continue;
466 }
467 FOREACH_THREAD_IN_PROC(p, td) {
468 awake = 0;
469 ts = td_get_sched(td);
470 thread_lock(td);
471 /*
472 * Increment sleep time (if sleeping). We
473 * ignore overflow, as above.
474 */
475 /*
476 * The td_sched slptimes are not touched in wakeup
477 * because the thread may not HAVE everything in
478 * memory? XXX I think this is out of date.
479 */
480 if (TD_ON_RUNQ(td)) {
481 awake = 1;
482 td->td_flags &= ~TDF_DIDRUN;
483 } else if (TD_IS_RUNNING(td)) {
484 awake = 1;
485 /* Do not clear TDF_DIDRUN */
486 } else if (td->td_flags & TDF_DIDRUN) {
487 awake = 1;
488 td->td_flags &= ~TDF_DIDRUN;
489 }
490
491 /*
492 * ts_pctcpu is only for ps and ttyinfo().
493 */
494 ts->ts_pctcpu = (ts->ts_pctcpu * ccpu) >> FSHIFT;
495 /*
496 * If the td_sched has been idle the entire second,
497 * stop recalculating its priority until
498 * it wakes up.
499 */
500 if (ts->ts_cpticks != 0) {
501 #if (FSHIFT >= CCPU_SHIFT)
502 ts->ts_pctcpu += (realstathz == 100)
503 ? ((fixpt_t) ts->ts_cpticks) <<
504 (FSHIFT - CCPU_SHIFT) :
505 100 * (((fixpt_t) ts->ts_cpticks)
506 << (FSHIFT - CCPU_SHIFT)) / realstathz;
507 #else
508 ts->ts_pctcpu += ((FSCALE - ccpu) *
509 (ts->ts_cpticks *
510 FSCALE / realstathz)) >> FSHIFT;
511 #endif
512 ts->ts_cpticks = 0;
513 }
514 /*
515 * If there are ANY running threads in this process,
516 * then don't count it as sleeping.
517 * XXX: this is broken.
518 */
519 if (awake) {
520 if (ts->ts_slptime > 1) {
521 /*
522 * In an ideal world, this should not
523 * happen, because whoever woke us
524 * up from the long sleep should have
525 * unwound the slptime and reset our
526 * priority before we run at the stale
527 * priority. Should KASSERT at some
528 * point when all the cases are fixed.
529 */
530 updatepri(td);
531 }
532 ts->ts_slptime = 0;
533 } else
534 ts->ts_slptime++;
535 if (ts->ts_slptime > 1) {
536 thread_unlock(td);
537 continue;
538 }
539 ts->ts_estcpu = decay_cpu(loadfac, ts->ts_estcpu);
540 resetpriority(td);
541 resetpriority_thread(td);
542 thread_unlock(td);
543 }
544 PROC_UNLOCK(p);
545 }
546 sx_sunlock(&allproc_lock);
547 }
548
549 /*
550 * Main loop for a kthread that executes schedcpu once a second.
551 */
552 static void
schedcpu_thread(void)553 schedcpu_thread(void)
554 {
555
556 for (;;) {
557 schedcpu();
558 pause("-", hz);
559 }
560 }
561
562 /*
563 * Recalculate the priority of a process after it has slept for a while.
564 * For all load averages >= 1 and max ts_estcpu of 255, sleeping for at
565 * least six times the loadfactor will decay ts_estcpu to zero.
566 */
567 static void
updatepri(struct thread * td)568 updatepri(struct thread *td)
569 {
570 struct td_sched *ts;
571 fixpt_t loadfac;
572 unsigned int newcpu;
573
574 ts = td_get_sched(td);
575 loadfac = loadfactor(averunnable.ldavg[0]);
576 if (ts->ts_slptime > 5 * loadfac)
577 ts->ts_estcpu = 0;
578 else {
579 newcpu = ts->ts_estcpu;
580 ts->ts_slptime--; /* was incremented in schedcpu() */
581 while (newcpu && --ts->ts_slptime)
582 newcpu = decay_cpu(loadfac, newcpu);
583 ts->ts_estcpu = newcpu;
584 }
585 }
586
587 /*
588 * Compute the priority of a process when running in user mode.
589 * Arrange to reschedule if the resulting priority is better
590 * than that of the current process.
591 */
592 static void
resetpriority(struct thread * td)593 resetpriority(struct thread *td)
594 {
595 u_int newpriority;
596
597 if (td->td_pri_class != PRI_TIMESHARE)
598 return;
599 newpriority = PRI_MIN_TIMESHARE +
600 td_get_sched(td)->ts_estcpu / INVERSE_ESTCPU_WEIGHT +
601 NICE_WEIGHT * (td->td_proc->p_nice - PRIO_MIN);
602 KASSERT(PRI_MIN_TIMESHARE <= newpriority &&
603 newpriority <= PRI_MAX_TIMESHARE,
604 ("Out-of-bounds priority, probably 'ts_estcpu' not clamped "
605 "correctly, see ESTCPULIM()"));
606 sched_user_prio(td, newpriority);
607 }
608
609 /*
610 * Update the thread's priority when the associated process's user
611 * priority changes.
612 */
613 static void
resetpriority_thread(struct thread * td)614 resetpriority_thread(struct thread *td)
615 {
616
617 /* Only change threads with a time sharing user priority. */
618 if (td->td_priority < PRI_MIN_TIMESHARE ||
619 td->td_priority > PRI_MAX_TIMESHARE)
620 return;
621
622 /* XXX the whole needresched thing is broken, but not silly. */
623 maybe_resched(td);
624
625 sched_prio(td, td->td_user_pri);
626 }
627
628 static void
sched_4bsd_setup(void)629 sched_4bsd_setup(void)
630 {
631 /*
632 * Decay 95% of `ts_pctcpu' in 60 seconds; see CCPU_SHIFT
633 * before changing.
634 */
635 ccpu = 0.95122942450071400909 * FSCALE; /* exp(-1/20) */
636
637 setup_runqs();
638
639 /* Account for thread0. */
640 sched_load_add();
641
642 ast_register(TDA_SCHED_PRIV, ASTR_UNCOND, 0, maybe_resched_ast);
643 }
644
645 /*
646 * This routine determines time constants after stathz and hz are setup.
647 */
648 static void
sched_4bsd_initticks(void)649 sched_4bsd_initticks(void)
650 {
651
652 realstathz = stathz ? stathz : hz;
653 sched_slice = realstathz / 10; /* ~100ms */
654 hogticks = imax(1, (2 * hz * sched_slice + realstathz / 2) /
655 realstathz);
656 }
657
658 /* External interfaces start here */
659
660 /*
661 * Very early in the boot some setup of scheduler-specific
662 * parts of proc0 and of some scheduler resources needs to be done.
663 * Called from:
664 * proc0_init()
665 */
666 static void
sched_4bsd_init(void)667 sched_4bsd_init(void)
668 {
669
670 /*
671 * Set up the scheduler specific parts of thread0.
672 */
673 thread0.td_lock = &sched_lock;
674 td_get_sched(&thread0)->ts_slice = sched_slice;
675 mtx_init(&sched_lock, "sched lock", NULL, MTX_SPIN);
676 }
677
678 static void
sched_4bsd_init_ap(void)679 sched_4bsd_init_ap(void)
680 {
681
682 /* Nothing needed. */
683 }
684
685 static bool
sched_4bsd_runnable(void)686 sched_4bsd_runnable(void)
687 {
688 #ifdef SMP
689 return (runq_not_empty(&runq_global) ||
690 runq_not_empty(DPCPU_PTR(runq_pcpu)));
691 #else
692 return (runq_not_empty(&runq_global));
693 #endif
694 }
695
696 static int
sched_4bsd_rr_interval(void)697 sched_4bsd_rr_interval(void)
698 {
699
700 /* Convert sched_slice from stathz to hz. */
701 return (imax(1, (sched_slice * hz + realstathz / 2) / realstathz));
702 }
703
704 /*
705 * We adjust the priority of the current process. The priority of a
706 * process gets worse as it accumulates CPU time. The cpu usage
707 * estimator (ts_estcpu) is increased here. resetpriority() will
708 * compute a different priority each time ts_estcpu increases by
709 * INVERSE_ESTCPU_WEIGHT (until PRI_MAX_TIMESHARE is reached). The
710 * cpu usage estimator ramps up quite quickly when the process is
711 * running (linearly), and decays away exponentially, at a rate which
712 * is proportionally slower when the system is busy. The basic
713 * principle is that the system will 90% forget that the process used
714 * a lot of CPU time in 5 * loadav seconds. This causes the system to
715 * favor processes which haven't run much recently, and to round-robin
716 * among other processes.
717 */
718 static void
sched_clock_tick(struct thread * td)719 sched_clock_tick(struct thread *td)
720 {
721 struct pcpuidlestat *stat;
722 struct td_sched *ts;
723
724 THREAD_LOCK_ASSERT(td, MA_OWNED);
725 ts = td_get_sched(td);
726
727 ts->ts_cpticks++;
728 ts->ts_estcpu = ESTCPULIM(ts->ts_estcpu + 1);
729 if ((ts->ts_estcpu % INVERSE_ESTCPU_WEIGHT) == 0) {
730 resetpriority(td);
731 resetpriority_thread(td);
732 }
733
734 /*
735 * Force a context switch if the current thread has used up a full
736 * time slice (default is 100ms).
737 */
738 if (!TD_IS_IDLETHREAD(td) && --ts->ts_slice <= 0) {
739 ts->ts_slice = sched_slice;
740
741 /*
742 * If an ithread uses a full quantum, demote its
743 * priority and preempt it.
744 */
745 if (PRI_BASE(td->td_pri_class) == PRI_ITHD) {
746 SCHED_STAT_INC(ithread_preemptions);
747 td->td_owepreempt = 1;
748 if (td->td_base_pri + RQ_PPQ < PRI_MAX_ITHD) {
749 SCHED_STAT_INC(ithread_demotions);
750 sched_prio(td, td->td_base_pri + RQ_PPQ);
751 }
752 } else {
753 td->td_flags |= TDF_SLICEEND;
754 ast_sched_locked(td, TDA_SCHED);
755 }
756 }
757
758 stat = DPCPU_PTR(idlestat);
759 stat->oldidlecalls = stat->idlecalls;
760 stat->idlecalls = 0;
761 }
762
763 static void
sched_4bsd_clock(struct thread * td,int cnt)764 sched_4bsd_clock(struct thread *td, int cnt)
765 {
766
767 for ( ; cnt > 0; cnt--)
768 sched_clock_tick(td);
769 }
770
771 /*
772 * Charge child's scheduling CPU usage to parent.
773 */
774 static void
sched_4bsd_exit(struct proc * p,struct thread * td)775 sched_4bsd_exit(struct proc *p, struct thread *td)
776 {
777
778 KTR_STATE1(KTR_SCHED, "thread", sched_tdname(td), "proc exit",
779 "prio:%d", td->td_priority);
780
781 PROC_LOCK_ASSERT(p, MA_OWNED);
782 sched_exit_thread(FIRST_THREAD_IN_PROC(p), td);
783 }
784
785 static void
sched_4bsd_exit_thread(struct thread * td,struct thread * child)786 sched_4bsd_exit_thread(struct thread *td, struct thread *child)
787 {
788
789 KTR_STATE1(KTR_SCHED, "thread", sched_tdname(child), "exit",
790 "prio:%d", child->td_priority);
791 thread_lock(td);
792 td_get_sched(td)->ts_estcpu = ESTCPULIM(td_get_sched(td)->ts_estcpu +
793 td_get_sched(child)->ts_estcpu);
794 thread_unlock(td);
795 thread_lock(child);
796 if ((child->td_flags & TDF_NOLOAD) == 0)
797 sched_load_rem();
798 thread_unlock(child);
799 }
800
801 static void
sched_4bsd_fork(struct thread * td,struct thread * childtd)802 sched_4bsd_fork(struct thread *td, struct thread *childtd)
803 {
804 sched_fork_thread(td, childtd);
805 }
806
807 static void
sched_4bsd_fork_thread(struct thread * td,struct thread * childtd)808 sched_4bsd_fork_thread(struct thread *td, struct thread *childtd)
809 {
810 struct td_sched *ts, *tsc;
811
812 childtd->td_oncpu = NOCPU;
813 childtd->td_lastcpu = NOCPU;
814 childtd->td_lock = &sched_lock;
815 childtd->td_cpuset = cpuset_ref(td->td_cpuset);
816 childtd->td_domain.dr_policy = td->td_cpuset->cs_domain;
817 childtd->td_priority = childtd->td_base_pri;
818 ts = td_get_sched(childtd);
819 bzero(ts, sizeof(*ts));
820 tsc = td_get_sched(td);
821 ts->ts_estcpu = tsc->ts_estcpu;
822 ts->ts_flags |= (tsc->ts_flags & TSF_AFFINITY);
823 ts->ts_slice = 1;
824 }
825
826 static void
sched_4bsd_nice(struct proc * p,int nice)827 sched_4bsd_nice(struct proc *p, int nice)
828 {
829 struct thread *td;
830
831 PROC_LOCK_ASSERT(p, MA_OWNED);
832 p->p_nice = nice;
833 FOREACH_THREAD_IN_PROC(p, td) {
834 thread_lock(td);
835 resetpriority(td);
836 resetpriority_thread(td);
837 thread_unlock(td);
838 }
839 }
840
841 static void
sched_4bsd_class(struct thread * td,int class)842 sched_4bsd_class(struct thread *td, int class)
843 {
844 THREAD_LOCK_ASSERT(td, MA_OWNED);
845 td->td_pri_class = class;
846 }
847
848 /*
849 * Adjust the priority of a thread.
850 */
851 static void
sched_priority(struct thread * td,u_char prio)852 sched_priority(struct thread *td, u_char prio)
853 {
854
855 KTR_POINT3(KTR_SCHED, "thread", sched_tdname(td), "priority change",
856 "prio:%d", td->td_priority, "new prio:%d", prio, KTR_ATTR_LINKED,
857 sched_tdname(curthread));
858 SDT_PROBE3(sched, , , change__pri, td, td->td_proc, prio);
859 if (td != curthread && prio > td->td_priority) {
860 KTR_POINT3(KTR_SCHED, "thread", sched_tdname(curthread),
861 "lend prio", "prio:%d", td->td_priority, "new prio:%d",
862 prio, KTR_ATTR_LINKED, sched_tdname(td));
863 SDT_PROBE4(sched, , , lend__pri, td, td->td_proc, prio,
864 curthread);
865 }
866 THREAD_LOCK_ASSERT(td, MA_OWNED);
867 if (td->td_priority == prio)
868 return;
869 td->td_priority = prio;
870 if (TD_ON_RUNQ(td) && td->td_rqindex != RQ_PRI_TO_QUEUE_IDX(prio)) {
871 sched_rem(td);
872 sched_add(td, SRQ_BORING | SRQ_HOLDTD);
873 }
874 }
875
876 /*
877 * Update a thread's priority when it is lent another thread's
878 * priority.
879 */
880 static void
sched_4bsd_lend_prio(struct thread * td,u_char prio)881 sched_4bsd_lend_prio(struct thread *td, u_char prio)
882 {
883
884 td->td_flags |= TDF_BORROWING;
885 sched_priority(td, prio);
886 }
887
888 /*
889 * Restore a thread's priority when priority propagation is
890 * over. The prio argument is the minimum priority the thread
891 * needs to have to satisfy other possible priority lending
892 * requests. If the thread's regulary priority is less
893 * important than prio the thread will keep a priority boost
894 * of prio.
895 */
896 static void
sched_4bsd_unlend_prio(struct thread * td,u_char prio)897 sched_4bsd_unlend_prio(struct thread *td, u_char prio)
898 {
899 u_char base_pri;
900
901 if (td->td_base_pri >= PRI_MIN_TIMESHARE &&
902 td->td_base_pri <= PRI_MAX_TIMESHARE)
903 base_pri = td->td_user_pri;
904 else
905 base_pri = td->td_base_pri;
906 if (prio >= base_pri) {
907 td->td_flags &= ~TDF_BORROWING;
908 sched_prio(td, base_pri);
909 } else
910 sched_lend_prio(td, prio);
911 }
912
913 static void
sched_4bsd_prio(struct thread * td,u_char prio)914 sched_4bsd_prio(struct thread *td, u_char prio)
915 {
916 u_char oldprio;
917
918 /* First, update the base priority. */
919 td->td_base_pri = prio;
920
921 /*
922 * If the thread is borrowing another thread's priority, don't ever
923 * lower the priority.
924 */
925 if (td->td_flags & TDF_BORROWING && td->td_priority < prio)
926 return;
927
928 /* Change the real priority. */
929 oldprio = td->td_priority;
930 sched_priority(td, prio);
931
932 /*
933 * If the thread is on a turnstile, then let the turnstile update
934 * its state.
935 */
936 if (TD_ON_LOCK(td) && oldprio != prio)
937 turnstile_adjust(td, oldprio);
938 }
939
940 static void
sched_4bsd_ithread_prio(struct thread * td,u_char prio)941 sched_4bsd_ithread_prio(struct thread *td, u_char prio)
942 {
943 THREAD_LOCK_ASSERT(td, MA_OWNED);
944 MPASS(td->td_pri_class == PRI_ITHD);
945 td->td_base_ithread_pri = prio;
946 sched_prio(td, prio);
947 }
948
949 static void
sched_4bsd_user_prio(struct thread * td,u_char prio)950 sched_4bsd_user_prio(struct thread *td, u_char prio)
951 {
952
953 THREAD_LOCK_ASSERT(td, MA_OWNED);
954 td->td_base_user_pri = prio;
955 if (td->td_lend_user_pri <= prio)
956 return;
957 td->td_user_pri = prio;
958 }
959
960 static void
sched_4bsd_lend_user_prio(struct thread * td,u_char prio)961 sched_4bsd_lend_user_prio(struct thread *td, u_char prio)
962 {
963
964 THREAD_LOCK_ASSERT(td, MA_OWNED);
965 td->td_lend_user_pri = prio;
966 td->td_user_pri = min(prio, td->td_base_user_pri);
967 if (td->td_priority > td->td_user_pri)
968 sched_prio(td, td->td_user_pri);
969 else if (td->td_priority != td->td_user_pri)
970 ast_sched_locked(td, TDA_SCHED);
971 }
972
973 /*
974 * Like the above but first check if there is anything to do.
975 */
976 static void
sched_4bsd_lend_user_prio_cond(struct thread * td,u_char prio)977 sched_4bsd_lend_user_prio_cond(struct thread *td, u_char prio)
978 {
979
980 if (td->td_lend_user_pri == prio)
981 return;
982
983 thread_lock(td);
984 sched_lend_user_prio(td, prio);
985 thread_unlock(td);
986 }
987
988 static void
sched_4bsd_sleep(struct thread * td,int pri)989 sched_4bsd_sleep(struct thread *td, int pri)
990 {
991
992 THREAD_LOCK_ASSERT(td, MA_OWNED);
993 td->td_slptick = ticks;
994 td_get_sched(td)->ts_slptime = 0;
995 if (pri != 0 && PRI_BASE(td->td_pri_class) == PRI_TIMESHARE)
996 sched_prio(td, pri);
997 }
998
999 static void
sched_4bsd_sswitch(struct thread * td,int flags)1000 sched_4bsd_sswitch(struct thread *td, int flags)
1001 {
1002 struct thread *newtd;
1003 struct mtx *tmtx;
1004 int preempted;
1005
1006 tmtx = &sched_lock;
1007
1008 THREAD_LOCK_ASSERT(td, MA_OWNED);
1009
1010 td->td_lastcpu = td->td_oncpu;
1011 preempted = (td->td_flags & TDF_SLICEEND) == 0 &&
1012 (flags & SW_PREEMPT) != 0;
1013 td->td_flags &= ~TDF_SLICEEND;
1014 ast_unsched_locked(td, TDA_SCHED);
1015 td->td_owepreempt = 0;
1016 td->td_oncpu = NOCPU;
1017
1018 /*
1019 * At the last moment, if this thread is still marked RUNNING,
1020 * then put it back on the run queue as it has not been suspended
1021 * or stopped or any thing else similar. We never put the idle
1022 * threads on the run queue, however.
1023 */
1024 if (td->td_flags & TDF_IDLETD) {
1025 TD_SET_CAN_RUN(td);
1026 #ifdef SMP
1027 CPU_CLR(PCPU_GET(cpuid), &idle_cpus_mask);
1028 #endif
1029 } else {
1030 if (TD_IS_RUNNING(td)) {
1031 /* Put us back on the run queue. */
1032 sched_add(td, SRQ_HOLDTD | SRQ_OURSELF | SRQ_YIELDING |
1033 (preempted ? SRQ_PREEMPTED : 0));
1034 }
1035 }
1036
1037 /*
1038 * Switch to the sched lock to fix things up and pick
1039 * a new thread. Block the td_lock in order to avoid
1040 * breaking the critical path.
1041 */
1042 if (td->td_lock != &sched_lock) {
1043 mtx_lock_spin(&sched_lock);
1044 tmtx = thread_lock_block(td);
1045 mtx_unlock_spin(tmtx);
1046 }
1047
1048 if ((td->td_flags & TDF_NOLOAD) == 0)
1049 sched_load_rem();
1050
1051 newtd = choosethread();
1052 MPASS(newtd->td_lock == &sched_lock);
1053
1054 #if (KTR_COMPILE & KTR_SCHED) != 0
1055 if (TD_IS_IDLETHREAD(td))
1056 KTR_STATE1(KTR_SCHED, "thread", sched_tdname(td), "idle",
1057 "prio:%d", td->td_priority);
1058 else
1059 KTR_STATE3(KTR_SCHED, "thread", sched_tdname(td), KTDSTATE(td),
1060 "prio:%d", td->td_priority, "wmesg:\"%s\"", td->td_wmesg,
1061 "lockname:\"%s\"", td->td_lockname);
1062 #endif
1063
1064 if (td != newtd) {
1065 #ifdef HWPMC_HOOKS
1066 if (PMC_PROC_IS_USING_PMCS(td->td_proc))
1067 PMC_SWITCH_CONTEXT(td, PMC_FN_CSW_OUT);
1068 #endif
1069
1070 #ifdef HWT_HOOKS
1071 HWT_CALL_HOOK(td, HWT_SWITCH_OUT, NULL);
1072 HWT_CALL_HOOK(newtd, HWT_SWITCH_IN, NULL);
1073 #endif
1074
1075 SDT_PROBE2(sched, , , off__cpu, newtd, newtd->td_proc);
1076
1077 /* I feel sleepy */
1078 lock_profile_release_lock(&sched_lock.lock_object, true);
1079 #ifdef KDTRACE_HOOKS
1080 /*
1081 * If DTrace has set the active vtime enum to anything
1082 * other than INACTIVE (0), then it should have set the
1083 * function to call.
1084 */
1085 if (dtrace_vtime_active)
1086 (*dtrace_vtime_switch_func)(newtd);
1087 #endif
1088
1089 cpu_switch(td, newtd, tmtx);
1090 lock_profile_obtain_lock_success(&sched_lock.lock_object, true,
1091 0, 0, __FILE__, __LINE__);
1092 /*
1093 * Where am I? What year is it?
1094 * We are in the same thread that went to sleep above,
1095 * but any amount of time may have passed. All our context
1096 * will still be available as will local variables.
1097 * PCPU values however may have changed as we may have
1098 * changed CPU so don't trust cached values of them.
1099 * New threads will go to fork_exit() instead of here
1100 * so if you change things here you may need to change
1101 * things there too.
1102 *
1103 * If the thread above was exiting it will never wake
1104 * up again here, so either it has saved everything it
1105 * needed to, or the thread_wait() or wait() will
1106 * need to reap it.
1107 */
1108
1109 SDT_PROBE0(sched, , , on__cpu);
1110 #ifdef HWPMC_HOOKS
1111 if (PMC_PROC_IS_USING_PMCS(td->td_proc))
1112 PMC_SWITCH_CONTEXT(td, PMC_FN_CSW_IN);
1113 #endif
1114 } else {
1115 td->td_lock = &sched_lock;
1116 SDT_PROBE0(sched, , , remain__cpu);
1117 }
1118
1119 KTR_STATE1(KTR_SCHED, "thread", sched_tdname(td), "running",
1120 "prio:%d", td->td_priority);
1121
1122 #ifdef SMP
1123 if (td->td_flags & TDF_IDLETD)
1124 CPU_SET(PCPU_GET(cpuid), &idle_cpus_mask);
1125 #endif
1126 sched_lock.mtx_lock = (uintptr_t)td;
1127 td->td_oncpu = PCPU_GET(cpuid);
1128 spinlock_enter();
1129 mtx_unlock_spin(&sched_lock);
1130 }
1131
1132 static void
sched_4bsd_wakeup(struct thread * td,int srqflags)1133 sched_4bsd_wakeup(struct thread *td, int srqflags)
1134 {
1135 struct td_sched *ts;
1136
1137 THREAD_LOCK_ASSERT(td, MA_OWNED);
1138 ts = td_get_sched(td);
1139 if (ts->ts_slptime > 1) {
1140 updatepri(td);
1141 resetpriority(td);
1142 }
1143 td->td_slptick = 0;
1144 ts->ts_slptime = 0;
1145 ts->ts_slice = sched_slice;
1146
1147 /*
1148 * When resuming an idle ithread, restore its base ithread
1149 * priority.
1150 */
1151 if (PRI_BASE(td->td_pri_class) == PRI_ITHD &&
1152 td->td_base_pri != td->td_base_ithread_pri)
1153 sched_prio(td, td->td_base_ithread_pri);
1154
1155 sched_add(td, srqflags);
1156 }
1157
1158 #ifdef SMP
1159 static int
forward_wakeup(int cpunum)1160 forward_wakeup(int cpunum)
1161 {
1162 struct pcpu *pc;
1163 cpuset_t dontuse, map, map2;
1164 u_int id, me;
1165 int iscpuset;
1166
1167 mtx_assert(&sched_lock, MA_OWNED);
1168
1169 CTR0(KTR_RUNQ, "forward_wakeup()");
1170
1171 if ((!forward_wakeup_enabled) ||
1172 (forward_wakeup_use_mask == 0 && forward_wakeup_use_loop == 0))
1173 return (0);
1174 if (!smp_started || KERNEL_PANICKED())
1175 return (0);
1176
1177 forward_wakeups_requested++;
1178
1179 /*
1180 * Check the idle mask we received against what we calculated
1181 * before in the old version.
1182 */
1183 me = PCPU_GET(cpuid);
1184
1185 /* Don't bother if we should be doing it ourself. */
1186 if (CPU_ISSET(me, &idle_cpus_mask) &&
1187 (cpunum == NOCPU || me == cpunum))
1188 return (0);
1189
1190 CPU_SETOF(me, &dontuse);
1191 CPU_OR(&dontuse, &dontuse, &stopped_cpus);
1192 CPU_ZERO(&map2);
1193 if (forward_wakeup_use_loop) {
1194 STAILQ_FOREACH(pc, &cpuhead, pc_allcpu) {
1195 id = pc->pc_cpuid;
1196 if (!CPU_ISSET(id, &dontuse) &&
1197 pc->pc_curthread == pc->pc_idlethread) {
1198 CPU_SET(id, &map2);
1199 }
1200 }
1201 }
1202
1203 if (forward_wakeup_use_mask) {
1204 map = idle_cpus_mask;
1205 CPU_ANDNOT(&map, &map, &dontuse);
1206
1207 /* If they are both on, compare and use loop if different. */
1208 if (forward_wakeup_use_loop) {
1209 if (CPU_CMP(&map, &map2)) {
1210 printf("map != map2, loop method preferred\n");
1211 map = map2;
1212 }
1213 }
1214 } else {
1215 map = map2;
1216 }
1217
1218 /* If we only allow a specific CPU, then mask off all the others. */
1219 if (cpunum != NOCPU) {
1220 KASSERT((cpunum <= mp_maxcpus),("forward_wakeup: bad cpunum."));
1221 iscpuset = CPU_ISSET(cpunum, &map);
1222 if (iscpuset == 0)
1223 CPU_ZERO(&map);
1224 else
1225 CPU_SETOF(cpunum, &map);
1226 }
1227 if (!CPU_EMPTY(&map)) {
1228 forward_wakeups_delivered++;
1229 STAILQ_FOREACH(pc, &cpuhead, pc_allcpu) {
1230 id = pc->pc_cpuid;
1231 if (!CPU_ISSET(id, &map))
1232 continue;
1233 if (cpu_idle_wakeup(pc->pc_cpuid))
1234 CPU_CLR(id, &map);
1235 }
1236 if (!CPU_EMPTY(&map))
1237 ipi_selected(map, IPI_AST);
1238 return (1);
1239 }
1240 if (cpunum == NOCPU)
1241 printf("forward_wakeup: Idle processor not found\n");
1242 return (0);
1243 }
1244
1245 static void
kick_other_cpu(int pri,int cpuid)1246 kick_other_cpu(int pri, int cpuid)
1247 {
1248 struct pcpu *pcpu;
1249 int cpri;
1250
1251 pcpu = pcpu_find(cpuid);
1252 if (CPU_ISSET(cpuid, &idle_cpus_mask)) {
1253 forward_wakeups_delivered++;
1254 if (!cpu_idle_wakeup(cpuid))
1255 ipi_cpu(cpuid, IPI_AST);
1256 return;
1257 }
1258
1259 cpri = pcpu->pc_curthread->td_priority;
1260 if (pri >= cpri)
1261 return;
1262
1263 #if defined(IPI_PREEMPTION) && defined(PREEMPTION)
1264 #if !defined(FULL_PREEMPTION)
1265 if (pri <= PRI_MAX_ITHD)
1266 #endif /* ! FULL_PREEMPTION */
1267 {
1268 ipi_cpu(cpuid, IPI_PREEMPT);
1269 return;
1270 }
1271 #endif /* defined(IPI_PREEMPTION) && defined(PREEMPTION) */
1272
1273 if (pcpu->pc_curthread->td_lock == &sched_lock) {
1274 ast_sched_locked(pcpu->pc_curthread, TDA_SCHED);
1275 ipi_cpu(cpuid, IPI_AST);
1276 }
1277 }
1278 #endif /* SMP */
1279
1280 #ifdef SMP
1281 static int
sched_pickcpu(struct thread * td)1282 sched_pickcpu(struct thread *td)
1283 {
1284 int best, cpu;
1285
1286 mtx_assert(&sched_lock, MA_OWNED);
1287
1288 if (td->td_lastcpu != NOCPU && THREAD_CAN_SCHED(td, td->td_lastcpu))
1289 best = td->td_lastcpu;
1290 else
1291 best = NOCPU;
1292 CPU_FOREACH(cpu) {
1293 if (!THREAD_CAN_SCHED(td, cpu))
1294 continue;
1295
1296 if (best == NOCPU)
1297 best = cpu;
1298 else if (DPCPU_ID_GET(cpu, runq_length) < DPCPU_ID_GET(best, runq_length))
1299 best = cpu;
1300 }
1301 KASSERT(best != NOCPU, ("no valid CPUs"));
1302
1303 return (best);
1304 }
1305 #endif
1306
1307 static void
sched_4bsd_add(struct thread * td,int flags)1308 sched_4bsd_add(struct thread *td, int flags)
1309 #ifdef SMP
1310 {
1311 cpuset_t tidlemsk;
1312 struct td_sched *ts;
1313 u_int cpu, cpuid;
1314 int forwarded = 0;
1315 int single_cpu = 0;
1316
1317 ts = td_get_sched(td);
1318 THREAD_LOCK_ASSERT(td, MA_OWNED);
1319 KASSERT((td->td_inhibitors == 0),
1320 ("sched_add: trying to run inhibited thread"));
1321 KASSERT((TD_CAN_RUN(td) || TD_IS_RUNNING(td)),
1322 ("sched_add: bad thread state"));
1323 KASSERT(td->td_flags & TDF_INMEM,
1324 ("sched_add: thread swapped out"));
1325
1326 KTR_STATE2(KTR_SCHED, "thread", sched_tdname(td), "runq add",
1327 "prio:%d", td->td_priority, KTR_ATTR_LINKED,
1328 sched_tdname(curthread));
1329 KTR_POINT1(KTR_SCHED, "thread", sched_tdname(curthread), "wokeup",
1330 KTR_ATTR_LINKED, sched_tdname(td));
1331 SDT_PROBE4(sched, , , enqueue, td, td->td_proc, NULL,
1332 flags & SRQ_PREEMPTED);
1333
1334 /*
1335 * Now that the thread is moving to the run-queue, set the lock
1336 * to the scheduler's lock.
1337 */
1338 if (td->td_lock != &sched_lock) {
1339 mtx_lock_spin(&sched_lock);
1340 if ((flags & SRQ_HOLD) != 0)
1341 td->td_lock = &sched_lock;
1342 else
1343 thread_lock_set(td, &sched_lock);
1344 }
1345 TD_SET_RUNQ(td);
1346
1347 /*
1348 * If SMP is started and the thread is pinned or otherwise limited to
1349 * a specific set of CPUs, queue the thread to a per-CPU run queue.
1350 * Otherwise, queue the thread to the global run queue.
1351 *
1352 * If SMP has not yet been started we must use the global run queue
1353 * as per-CPU state may not be initialized yet and we may crash if we
1354 * try to access the per-CPU run queues.
1355 */
1356 if (smp_started && (td->td_pinned != 0 || td->td_flags & TDF_BOUND ||
1357 ts->ts_flags & TSF_AFFINITY)) {
1358 if (td->td_pinned != 0)
1359 cpu = td->td_lastcpu;
1360 else if (td->td_flags & TDF_BOUND) {
1361 /* Find CPU from bound runq. */
1362 KASSERT(ts->ts_rqcpu != NOCPU,
1363 ("sched_add: bound td_sched not on cpu runq"));
1364 cpu = ts->ts_rqcpu;
1365 } else
1366 /* Find a valid CPU for our cpuset */
1367 cpu = sched_pickcpu(td);
1368 ts->ts_rqcpu = cpu;
1369 single_cpu = 1;
1370 CTR3(KTR_RUNQ,
1371 "sched_add: Put td_sched:%p(td:%p) on cpu%d runq", ts, td,
1372 cpu);
1373 } else {
1374 CTR2(KTR_RUNQ,
1375 "sched_add: adding td_sched:%p (td:%p) to gbl runq", ts,
1376 td);
1377 cpu = NOCPU;
1378 ts->ts_rqcpu = NOCPU;
1379 }
1380
1381 if ((td->td_flags & TDF_NOLOAD) == 0)
1382 sched_load_add();
1383 runq_add(TS_RUNQ_PTR(ts), td, flags);
1384 if (cpu != NOCPU)
1385 (*DPCPU_ID_PTR(cpu, runq_length))++;
1386
1387 cpuid = PCPU_GET(cpuid);
1388 if (single_cpu && cpu != cpuid) {
1389 kick_other_cpu(td->td_priority, cpu);
1390 } else {
1391 if (!single_cpu) {
1392 tidlemsk = idle_cpus_mask;
1393 CPU_CLR(cpuid, &tidlemsk);
1394
1395 if (!CPU_ISSET(cpuid, &idle_cpus_mask) &&
1396 ((flags & SRQ_INTR) == 0) &&
1397 !CPU_EMPTY(&tidlemsk))
1398 forwarded = forward_wakeup(cpu);
1399 }
1400
1401 if (!forwarded) {
1402 if (!maybe_preempt(td))
1403 maybe_resched(td);
1404 }
1405 }
1406 if ((flags & SRQ_HOLDTD) == 0)
1407 thread_unlock(td);
1408 }
1409 #else /* SMP */
1410 {
1411 struct td_sched *ts;
1412
1413 ts = td_get_sched(td);
1414 THREAD_LOCK_ASSERT(td, MA_OWNED);
1415 KASSERT((td->td_inhibitors == 0),
1416 ("sched_add: trying to run inhibited thread"));
1417 KASSERT((TD_CAN_RUN(td) || TD_IS_RUNNING(td)),
1418 ("sched_add: bad thread state"));
1419 KASSERT(td->td_flags & TDF_INMEM,
1420 ("sched_add: thread swapped out"));
1421 KTR_STATE2(KTR_SCHED, "thread", sched_tdname(td), "runq add",
1422 "prio:%d", td->td_priority, KTR_ATTR_LINKED,
1423 sched_tdname(curthread));
1424 KTR_POINT1(KTR_SCHED, "thread", sched_tdname(curthread), "wokeup",
1425 KTR_ATTR_LINKED, sched_tdname(td));
1426 SDT_PROBE4(sched, , , enqueue, td, td->td_proc, NULL,
1427 flags & SRQ_PREEMPTED);
1428
1429 /*
1430 * Now that the thread is moving to the run-queue, set the lock
1431 * to the scheduler's lock.
1432 */
1433 if (td->td_lock != &sched_lock) {
1434 mtx_lock_spin(&sched_lock);
1435 if ((flags & SRQ_HOLD) != 0)
1436 td->td_lock = &sched_lock;
1437 else
1438 thread_lock_set(td, &sched_lock);
1439 }
1440 TD_SET_RUNQ(td);
1441 CTR2(KTR_RUNQ, "sched_add: adding td_sched:%p (td:%p) to runq", ts, td);
1442 ts->ts_rqcpu = NOCPU;
1443
1444 if ((td->td_flags & TDF_NOLOAD) == 0)
1445 sched_load_add();
1446 runq_add(TS_RUNQ_PTR(ts), td, flags);
1447 if (!maybe_preempt(td))
1448 maybe_resched(td);
1449 if ((flags & SRQ_HOLDTD) == 0)
1450 thread_unlock(td);
1451 }
1452 #endif /* SMP */
1453
1454 static void
sched_4bsd_rem(struct thread * td)1455 sched_4bsd_rem(struct thread *td)
1456 {
1457 struct td_sched *ts;
1458
1459 ts = td_get_sched(td);
1460 KASSERT(td->td_flags & TDF_INMEM,
1461 ("sched_rem: thread swapped out"));
1462 KASSERT(TD_ON_RUNQ(td),
1463 ("sched_rem: thread not on run queue"));
1464 mtx_assert(&sched_lock, MA_OWNED);
1465 KTR_STATE2(KTR_SCHED, "thread", sched_tdname(td), "runq rem",
1466 "prio:%d", td->td_priority, KTR_ATTR_LINKED,
1467 sched_tdname(curthread));
1468 SDT_PROBE3(sched, , , dequeue, td, td->td_proc, NULL);
1469
1470 if ((td->td_flags & TDF_NOLOAD) == 0)
1471 sched_load_rem();
1472 #ifdef SMP
1473 if (ts->ts_rqcpu != NOCPU)
1474 (*DPCPU_ID_PTR(ts->ts_rqcpu, runq_length))--;
1475 #endif
1476 runq_remove(TS_RUNQ_PTR(ts), td);
1477 TD_SET_CAN_RUN(td);
1478 }
1479
1480 /*
1481 * Select threads to run. Note that running threads still consume a
1482 * slot.
1483 */
1484 static struct thread *
sched_4bsd_choose(void)1485 sched_4bsd_choose(void)
1486 {
1487 struct thread *td;
1488 struct runq *runq;
1489
1490 mtx_assert(&sched_lock, MA_OWNED);
1491 #ifdef SMP
1492 struct thread *tdcpu;
1493
1494 runq = &runq_global;
1495 td = runq_choose_fuzz(&runq_global, runq_fuzz);
1496 tdcpu = runq_choose(DPCPU_PTR(runq_pcpu));
1497
1498 if (td == NULL ||
1499 (tdcpu != NULL &&
1500 tdcpu->td_priority < td->td_priority)) {
1501 CTR2(KTR_RUNQ, "choosing td %p from pcpu runq %d", tdcpu,
1502 PCPU_GET(cpuid));
1503 td = tdcpu;
1504 runq = DPCPU_PTR(runq_pcpu);
1505 } else {
1506 CTR1(KTR_RUNQ, "choosing td_sched %p from main runq", td);
1507 }
1508
1509 #else
1510 runq = &runq_global;
1511 td = runq_choose(&runq_global);
1512 #endif
1513
1514 if (td) {
1515 #ifdef SMP
1516 if (td == tdcpu)
1517 (*DPCPU_PTR(runq_length))--;
1518 #endif
1519 runq_remove(runq, td);
1520 td->td_flags |= TDF_DIDRUN;
1521
1522 KASSERT(td->td_flags & TDF_INMEM,
1523 ("sched_choose: thread swapped out"));
1524 return (td);
1525 }
1526 return (PCPU_GET(idlethread));
1527 }
1528
1529 static void
sched_4bsd_preempt(struct thread * td)1530 sched_4bsd_preempt(struct thread *td)
1531 {
1532 int flags;
1533
1534 SDT_PROBE2(sched, , , surrender, td, td->td_proc);
1535 if (td->td_critnest > 1) {
1536 td->td_owepreempt = 1;
1537 } else {
1538 thread_lock(td);
1539 flags = SW_INVOL | SW_PREEMPT;
1540 flags |= TD_IS_IDLETHREAD(td) ? SWT_REMOTEWAKEIDLE :
1541 SWT_REMOTEPREEMPT;
1542 mi_switch(flags);
1543 }
1544 }
1545
1546 static void
sched_4bsd_userret_slowpath(struct thread * td)1547 sched_4bsd_userret_slowpath(struct thread *td)
1548 {
1549
1550 thread_lock(td);
1551 td->td_priority = td->td_user_pri;
1552 td->td_base_pri = td->td_user_pri;
1553 thread_unlock(td);
1554 }
1555
1556 static void
sched_4bsd_bind(struct thread * td,int cpu)1557 sched_4bsd_bind(struct thread *td, int cpu)
1558 {
1559 #ifdef SMP
1560 struct td_sched *ts = td_get_sched(td);
1561 #endif
1562
1563 THREAD_LOCK_ASSERT(td, MA_OWNED|MA_NOTRECURSED);
1564 KASSERT(td == curthread, ("sched_bind: can only bind curthread"));
1565
1566 td->td_flags |= TDF_BOUND;
1567 #ifdef SMP
1568 ts->ts_rqcpu = cpu;
1569 if (PCPU_GET(cpuid) == cpu)
1570 return;
1571
1572 mi_switch(SW_VOL | SWT_BIND);
1573 thread_lock(td);
1574 #endif
1575 }
1576
1577 static void
sched_4bsd_unbind(struct thread * td)1578 sched_4bsd_unbind(struct thread* td)
1579 {
1580 THREAD_LOCK_ASSERT(td, MA_OWNED);
1581 KASSERT(td == curthread, ("sched_unbind: can only bind curthread"));
1582 td->td_flags &= ~TDF_BOUND;
1583 }
1584
1585 static int
sched_4bsd_is_bound(struct thread * td)1586 sched_4bsd_is_bound(struct thread *td)
1587 {
1588 THREAD_LOCK_ASSERT(td, MA_OWNED);
1589 return (td->td_flags & TDF_BOUND);
1590 }
1591
1592 static void
sched_4bsd_relinquish(struct thread * td)1593 sched_4bsd_relinquish(struct thread *td)
1594 {
1595 thread_lock(td);
1596 mi_switch(SW_VOL | SWT_RELINQUISH);
1597 }
1598
1599 static int
sched_4bsd_load(void)1600 sched_4bsd_load(void)
1601 {
1602 return (sched_tdcnt);
1603 }
1604
1605 static int
sched_4bsd_sizeof_proc(void)1606 sched_4bsd_sizeof_proc(void)
1607 {
1608 return (sizeof(struct proc));
1609 }
1610
1611 static int
sched_4bsd_sizeof_thread(void)1612 sched_4bsd_sizeof_thread(void)
1613 {
1614 return (sizeof(struct thread) + sizeof(struct td_sched));
1615 }
1616
1617 static fixpt_t
sched_4bsd_pctcpu(struct thread * td)1618 sched_4bsd_pctcpu(struct thread *td)
1619 {
1620 struct td_sched *ts;
1621
1622 THREAD_LOCK_ASSERT(td, MA_OWNED);
1623 ts = td_get_sched(td);
1624 return (ts->ts_pctcpu);
1625 }
1626
1627 static u_int
sched_4bsd_estcpu(struct thread * td)1628 sched_4bsd_estcpu(struct thread *td)
1629 {
1630
1631 return (td_get_sched(td)->ts_estcpu);
1632 }
1633
1634 /*
1635 * The actual idle process.
1636 */
1637 static void
sched_4bsd_idletd(void * dummy)1638 sched_4bsd_idletd(void *dummy)
1639 {
1640 struct pcpuidlestat *stat;
1641
1642 THREAD_NO_SLEEPING();
1643 stat = DPCPU_PTR(idlestat);
1644 for (;;) {
1645 mtx_assert(&Giant, MA_NOTOWNED);
1646
1647 while (!sched_runnable()) {
1648 cpu_idle(stat->idlecalls + stat->oldidlecalls > 64);
1649 stat->idlecalls++;
1650 }
1651
1652 mtx_lock_spin(&sched_lock);
1653 mi_switch(SW_VOL | SWT_IDLE);
1654 }
1655 }
1656
1657 static void
sched_throw_tail(struct thread * td)1658 sched_throw_tail(struct thread *td)
1659 {
1660 struct thread *newtd;
1661
1662 mtx_assert(&sched_lock, MA_OWNED);
1663 KASSERT(curthread->td_md.md_spinlock_count == 1, ("invalid count"));
1664
1665 newtd = choosethread();
1666
1667 #ifdef HWT_HOOKS
1668 if (td)
1669 HWT_CALL_HOOK(td, HWT_SWITCH_OUT, NULL);
1670 HWT_CALL_HOOK(newtd, HWT_SWITCH_IN, NULL);
1671 #endif
1672
1673 cpu_throw(td, newtd); /* doesn't return */
1674 }
1675
1676 /*
1677 * A CPU is entering for the first time.
1678 */
1679 static void
sched_4bsd_ap_entry(void)1680 sched_4bsd_ap_entry(void)
1681 {
1682
1683 /*
1684 * Correct spinlock nesting. The idle thread context that we are
1685 * borrowing was created so that it would start out with a single
1686 * spin lock (sched_lock) held in fork_trampoline(). Since we've
1687 * explicitly acquired locks in this function, the nesting count
1688 * is now 2 rather than 1. Since we are nested, calling
1689 * spinlock_exit() will simply adjust the counts without allowing
1690 * spin lock using code to interrupt us.
1691 */
1692 mtx_lock_spin(&sched_lock);
1693 spinlock_exit();
1694 PCPU_SET(switchtime, cpu_ticks());
1695 PCPU_SET(switchticks, ticks);
1696
1697 sched_throw_tail(NULL);
1698 }
1699
1700 /*
1701 * A thread is exiting.
1702 */
1703 static void
sched_4bsd_throw(struct thread * td)1704 sched_4bsd_throw(struct thread *td)
1705 {
1706
1707 MPASS(td != NULL);
1708 MPASS(td->td_lock == &sched_lock);
1709
1710 lock_profile_release_lock(&sched_lock.lock_object, true);
1711 td->td_lastcpu = td->td_oncpu;
1712 td->td_oncpu = NOCPU;
1713
1714 sched_throw_tail(td);
1715 }
1716
1717 static void
sched_4bsd_fork_exit(struct thread * td)1718 sched_4bsd_fork_exit(struct thread *td)
1719 {
1720
1721 /*
1722 * Finish setting up thread glue so that it begins execution in a
1723 * non-nested critical section with sched_lock held but not recursed.
1724 */
1725 td->td_oncpu = PCPU_GET(cpuid);
1726 sched_lock.mtx_lock = (uintptr_t)td;
1727 lock_profile_obtain_lock_success(&sched_lock.lock_object, true,
1728 0, 0, __FILE__, __LINE__);
1729 THREAD_LOCK_ASSERT(td, MA_OWNED | MA_NOTRECURSED);
1730
1731 KTR_STATE1(KTR_SCHED, "thread", sched_tdname(td), "running",
1732 "prio:%d", td->td_priority);
1733 SDT_PROBE0(sched, , , on__cpu);
1734 }
1735
1736 static char *
sched_4bsd_tdname(struct thread * td)1737 sched_4bsd_tdname(struct thread *td)
1738 {
1739 #ifdef KTR
1740 struct td_sched *ts;
1741
1742 ts = td_get_sched(td);
1743 if (ts->ts_name[0] == '\0')
1744 snprintf(ts->ts_name, sizeof(ts->ts_name),
1745 "%s tid %d", td->td_name, td->td_tid);
1746 return (ts->ts_name);
1747 #else
1748 return (td->td_name);
1749 #endif
1750 }
1751
1752 static void
sched_4bsd_clear_tdname(struct thread * td)1753 sched_4bsd_clear_tdname(struct thread *td)
1754 {
1755 #ifdef KTR
1756 struct td_sched *ts;
1757
1758 ts = td_get_sched(td);
1759 ts->ts_name[0] = '\0';
1760 #endif
1761 }
1762
1763 static void
sched_4bsd_affinity(struct thread * td)1764 sched_4bsd_affinity(struct thread *td)
1765 {
1766 #ifdef SMP
1767 struct td_sched *ts;
1768 int cpu;
1769
1770 THREAD_LOCK_ASSERT(td, MA_OWNED);
1771
1772 /*
1773 * Set the TSF_AFFINITY flag if there is at least one CPU this
1774 * thread can't run on.
1775 */
1776 ts = td_get_sched(td);
1777 ts->ts_flags &= ~TSF_AFFINITY;
1778 CPU_FOREACH(cpu) {
1779 if (!THREAD_CAN_SCHED(td, cpu)) {
1780 ts->ts_flags |= TSF_AFFINITY;
1781 break;
1782 }
1783 }
1784
1785 /*
1786 * If this thread can run on all CPUs, nothing else to do.
1787 */
1788 if (!(ts->ts_flags & TSF_AFFINITY))
1789 return;
1790
1791 /* Pinned threads and bound threads should be left alone. */
1792 if (td->td_pinned != 0 || td->td_flags & TDF_BOUND)
1793 return;
1794
1795 switch (TD_GET_STATE(td)) {
1796 case TDS_RUNQ:
1797 /*
1798 * If we are on a per-CPU runqueue that is in the set,
1799 * then nothing needs to be done.
1800 */
1801 if (ts->ts_rqcpu != NOCPU && THREAD_CAN_SCHED(td, ts->ts_rqcpu))
1802 return;
1803
1804 /* Put this thread on a valid per-CPU runqueue. */
1805 sched_rem(td);
1806 sched_add(td, SRQ_HOLDTD | SRQ_BORING);
1807 break;
1808 case TDS_RUNNING:
1809 /*
1810 * See if our current CPU is in the set. If not, force a
1811 * context switch.
1812 */
1813 if (THREAD_CAN_SCHED(td, td->td_oncpu))
1814 return;
1815
1816 ast_sched_locked(td, TDA_SCHED);
1817 if (td != curthread)
1818 ipi_cpu(cpu, IPI_AST);
1819 break;
1820 default:
1821 break;
1822 }
1823 #endif
1824 }
1825
1826 static int
sched_4bsd_find_l2_neighbor(int cpu)1827 sched_4bsd_find_l2_neighbor(int cpu)
1828 {
1829 return (-1);
1830 }
1831
1832 struct sched_instance sched_4bsd_instance = {
1833 #define SLOT(name) .name = sched_4bsd_##name
1834 SLOT(load),
1835 SLOT(rr_interval),
1836 SLOT(runnable),
1837 SLOT(exit),
1838 SLOT(fork),
1839 SLOT(fork_exit),
1840 SLOT(class),
1841 SLOT(nice),
1842 SLOT(ap_entry),
1843 SLOT(exit_thread),
1844 SLOT(estcpu),
1845 SLOT(fork_thread),
1846 SLOT(ithread_prio),
1847 SLOT(lend_prio),
1848 SLOT(lend_user_prio),
1849 SLOT(lend_user_prio_cond),
1850 SLOT(pctcpu),
1851 SLOT(prio),
1852 SLOT(sleep),
1853 SLOT(sswitch),
1854 SLOT(throw),
1855 SLOT(unlend_prio),
1856 SLOT(user_prio),
1857 SLOT(userret_slowpath),
1858 SLOT(add),
1859 SLOT(choose),
1860 SLOT(clock),
1861 SLOT(idletd),
1862 SLOT(preempt),
1863 SLOT(relinquish),
1864 SLOT(rem),
1865 SLOT(wakeup),
1866 SLOT(bind),
1867 SLOT(unbind),
1868 SLOT(is_bound),
1869 SLOT(affinity),
1870 SLOT(sizeof_proc),
1871 SLOT(sizeof_thread),
1872 SLOT(tdname),
1873 SLOT(clear_tdname),
1874 SLOT(find_l2_neighbor),
1875 SLOT(init),
1876 SLOT(init_ap),
1877 SLOT(setup),
1878 SLOT(initticks),
1879 SLOT(schedcpu),
1880 #undef SLOT
1881 };
1882 DECLARE_SCHEDULER(fourbsd_sched_selector, "4BSD", &sched_4bsd_instance);
1883