xref: /freebsd/sys/kern/sched_4bsd.c (revision 7afc53b8dfcc7d5897920ce6cc7e842fbb4ab813)
1 /*-
2  * Copyright (c) 1982, 1986, 1990, 1991, 1993
3  *	The Regents of the University of California.  All rights reserved.
4  * (c) UNIX System Laboratories, Inc.
5  * All or some portions of this file are derived from material licensed
6  * to the University of California by American Telephone and Telegraph
7  * Co. or Unix System Laboratories, Inc. and are reproduced herein with
8  * the permission of UNIX System Laboratories, Inc.
9  *
10  * Redistribution and use in source and binary forms, with or without
11  * modification, are permitted provided that the following conditions
12  * are met:
13  * 1. Redistributions of source code must retain the above copyright
14  *    notice, this list of conditions and the following disclaimer.
15  * 2. Redistributions in binary form must reproduce the above copyright
16  *    notice, this list of conditions and the following disclaimer in the
17  *    documentation and/or other materials provided with the distribution.
18  * 4. Neither the name of the University nor the names of its contributors
19  *    may be used to endorse or promote products derived from this software
20  *    without specific prior written permission.
21  *
22  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
23  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
24  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
25  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
26  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
27  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
28  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
29  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
30  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
31  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
32  * SUCH DAMAGE.
33  */
34 
35 #include <sys/cdefs.h>
36 __FBSDID("$FreeBSD$");
37 
38 #define kse td_sched
39 
40 #include <sys/param.h>
41 #include <sys/systm.h>
42 #include <sys/kernel.h>
43 #include <sys/ktr.h>
44 #include <sys/lock.h>
45 #include <sys/kthread.h>
46 #include <sys/mutex.h>
47 #include <sys/proc.h>
48 #include <sys/resourcevar.h>
49 #include <sys/sched.h>
50 #include <sys/smp.h>
51 #include <sys/sysctl.h>
52 #include <sys/sx.h>
53 #include <sys/turnstile.h>
54 #include <machine/smp.h>
55 
56 #ifdef HWPMC_HOOKS
57 #include <sys/pmckern.h>
58 #endif
59 
60 /*
61  * INVERSE_ESTCPU_WEIGHT is only suitable for statclock() frequencies in
62  * the range 100-256 Hz (approximately).
63  */
64 #define	ESTCPULIM(e) \
65     min((e), INVERSE_ESTCPU_WEIGHT * (NICE_WEIGHT * (PRIO_MAX - PRIO_MIN) - \
66     RQ_PPQ) + INVERSE_ESTCPU_WEIGHT - 1)
67 #ifdef SMP
68 #define	INVERSE_ESTCPU_WEIGHT	(8 * smp_cpus)
69 #else
70 #define	INVERSE_ESTCPU_WEIGHT	8	/* 1 / (priorities per estcpu level). */
71 #endif
72 #define	NICE_WEIGHT		1	/* Priorities per nice level. */
73 
74 /*
75  * The schedulable entity that can be given a context to run.
76  * A process may have several of these. Probably one per processor
77  * but posibly a few more. In this universe they are grouped
78  * with a KSEG that contains the priority and niceness
79  * for the group.
80  */
81 struct kse {
82 	TAILQ_ENTRY(kse) ke_procq;	/* (j/z) Run queue. */
83 	struct thread	*ke_thread;	/* (*) Active associated thread. */
84 	fixpt_t		ke_pctcpu;	/* (j) %cpu during p_swtime. */
85 	char		ke_rqindex;	/* (j) Run queue index. */
86 	enum {
87 		KES_THREAD = 0x0,	/* slaved to thread state */
88 		KES_ONRUNQ
89 	} ke_state;			/* (j) KSE status. */
90 	int		ke_cpticks;	/* (j) Ticks of cpu time. */
91 	struct runq	*ke_runq;	/* runq the kse is currently on */
92 };
93 
94 #define ke_proc		ke_thread->td_proc
95 #define ke_ksegrp	ke_thread->td_ksegrp
96 
97 #define td_kse td_sched
98 
99 /* flags kept in td_flags */
100 #define TDF_DIDRUN	TDF_SCHED0	/* KSE actually ran. */
101 #define TDF_EXIT	TDF_SCHED1	/* KSE is being killed. */
102 #define TDF_BOUND	TDF_SCHED2
103 
104 #define ke_flags	ke_thread->td_flags
105 #define KEF_DIDRUN	TDF_DIDRUN /* KSE actually ran. */
106 #define KEF_EXIT	TDF_EXIT /* KSE is being killed. */
107 #define KEF_BOUND	TDF_BOUND /* stuck to one CPU */
108 
109 #define SKE_RUNQ_PCPU(ke)						\
110     ((ke)->ke_runq != 0 && (ke)->ke_runq != &runq)
111 
112 struct kg_sched {
113 	struct thread	*skg_last_assigned; /* (j) Last thread assigned to */
114 					   /* the system scheduler. */
115 	int	skg_avail_opennings;	/* (j) Num KSEs requested in group. */
116 	int	skg_concurrency;	/* (j) Num KSEs requested in group. */
117 };
118 #define kg_last_assigned	kg_sched->skg_last_assigned
119 #define kg_avail_opennings	kg_sched->skg_avail_opennings
120 #define kg_concurrency		kg_sched->skg_concurrency
121 
122 #define SLOT_RELEASE(kg)						\
123 do {									\
124 	kg->kg_avail_opennings++; 					\
125 	CTR3(KTR_RUNQ, "kg %p(%d) Slot released (->%d)",		\
126 	kg,								\
127 	kg->kg_concurrency,						\
128 	 kg->kg_avail_opennings);					\
129 /*	KASSERT((kg->kg_avail_opennings <= kg->kg_concurrency),		\
130 	    ("slots out of whack"));*/					\
131 } while (0)
132 
133 #define SLOT_USE(kg)							\
134 do {									\
135 	kg->kg_avail_opennings--; 					\
136 	CTR3(KTR_RUNQ, "kg %p(%d) Slot used (->%d)",			\
137 	kg,								\
138 	kg->kg_concurrency,						\
139 	 kg->kg_avail_opennings);					\
140 /*	KASSERT((kg->kg_avail_opennings >= 0),				\
141 	    ("slots out of whack"));*/					\
142 } while (0)
143 
144 /*
145  * KSE_CAN_MIGRATE macro returns true if the kse can migrate between
146  * cpus.
147  */
148 #define KSE_CAN_MIGRATE(ke)						\
149     ((ke)->ke_thread->td_pinned == 0 && ((ke)->ke_flags & KEF_BOUND) == 0)
150 
151 static struct kse kse0;
152 static struct kg_sched kg_sched0;
153 
154 static int	sched_tdcnt;	/* Total runnable threads in the system. */
155 static int	sched_quantum;	/* Roundrobin scheduling quantum in ticks. */
156 #define	SCHED_QUANTUM	(hz / 10)	/* Default sched quantum */
157 
158 static struct callout roundrobin_callout;
159 
160 static void	slot_fill(struct ksegrp *kg);
161 static struct kse *sched_choose(void);		/* XXX Should be thread * */
162 
163 static void	setup_runqs(void);
164 static void	roundrobin(void *arg);
165 static void	schedcpu(void);
166 static void	schedcpu_thread(void);
167 static void	sched_priority(struct thread *td, u_char prio);
168 static void	sched_setup(void *dummy);
169 static void	maybe_resched(struct thread *td);
170 static void	updatepri(struct ksegrp *kg);
171 static void	resetpriority(struct ksegrp *kg);
172 static void	resetpriority_thread(struct thread *td, struct ksegrp *kg);
173 #ifdef SMP
174 static int	forward_wakeup(int  cpunum);
175 #endif
176 
177 static struct kproc_desc sched_kp = {
178         "schedcpu",
179         schedcpu_thread,
180         NULL
181 };
182 SYSINIT(schedcpu, SI_SUB_RUN_SCHEDULER, SI_ORDER_FIRST, kproc_start, &sched_kp)
183 SYSINIT(sched_setup, SI_SUB_RUN_QUEUE, SI_ORDER_FIRST, sched_setup, NULL)
184 
185 /*
186  * Global run queue.
187  */
188 static struct runq runq;
189 
190 #ifdef SMP
191 /*
192  * Per-CPU run queues
193  */
194 static struct runq runq_pcpu[MAXCPU];
195 #endif
196 
197 static void
198 setup_runqs(void)
199 {
200 #ifdef SMP
201 	int i;
202 
203 	for (i = 0; i < MAXCPU; ++i)
204 		runq_init(&runq_pcpu[i]);
205 #endif
206 
207 	runq_init(&runq);
208 }
209 
210 static int
211 sysctl_kern_quantum(SYSCTL_HANDLER_ARGS)
212 {
213 	int error, new_val;
214 
215 	new_val = sched_quantum * tick;
216 	error = sysctl_handle_int(oidp, &new_val, 0, req);
217         if (error != 0 || req->newptr == NULL)
218 		return (error);
219 	if (new_val < tick)
220 		return (EINVAL);
221 	sched_quantum = new_val / tick;
222 	hogticks = 2 * sched_quantum;
223 	return (0);
224 }
225 
226 SYSCTL_NODE(_kern, OID_AUTO, sched, CTLFLAG_RD, 0, "Scheduler");
227 
228 SYSCTL_STRING(_kern_sched, OID_AUTO, name, CTLFLAG_RD, "4BSD", 0,
229     "Scheduler name");
230 
231 SYSCTL_PROC(_kern_sched, OID_AUTO, quantum, CTLTYPE_INT | CTLFLAG_RW,
232     0, sizeof sched_quantum, sysctl_kern_quantum, "I",
233     "Roundrobin scheduling quantum in microseconds");
234 
235 #ifdef SMP
236 /* Enable forwarding of wakeups to all other cpus */
237 SYSCTL_NODE(_kern_sched, OID_AUTO, ipiwakeup, CTLFLAG_RD, NULL, "Kernel SMP");
238 
239 static int forward_wakeup_enabled = 1;
240 SYSCTL_INT(_kern_sched_ipiwakeup, OID_AUTO, enabled, CTLFLAG_RW,
241 	   &forward_wakeup_enabled, 0,
242 	   "Forwarding of wakeup to idle CPUs");
243 
244 static int forward_wakeups_requested = 0;
245 SYSCTL_INT(_kern_sched_ipiwakeup, OID_AUTO, requested, CTLFLAG_RD,
246 	   &forward_wakeups_requested, 0,
247 	   "Requests for Forwarding of wakeup to idle CPUs");
248 
249 static int forward_wakeups_delivered = 0;
250 SYSCTL_INT(_kern_sched_ipiwakeup, OID_AUTO, delivered, CTLFLAG_RD,
251 	   &forward_wakeups_delivered, 0,
252 	   "Completed Forwarding of wakeup to idle CPUs");
253 
254 static int forward_wakeup_use_mask = 1;
255 SYSCTL_INT(_kern_sched_ipiwakeup, OID_AUTO, usemask, CTLFLAG_RW,
256 	   &forward_wakeup_use_mask, 0,
257 	   "Use the mask of idle cpus");
258 
259 static int forward_wakeup_use_loop = 0;
260 SYSCTL_INT(_kern_sched_ipiwakeup, OID_AUTO, useloop, CTLFLAG_RW,
261 	   &forward_wakeup_use_loop, 0,
262 	   "Use a loop to find idle cpus");
263 
264 static int forward_wakeup_use_single = 0;
265 SYSCTL_INT(_kern_sched_ipiwakeup, OID_AUTO, onecpu, CTLFLAG_RW,
266 	   &forward_wakeup_use_single, 0,
267 	   "Only signal one idle cpu");
268 
269 static int forward_wakeup_use_htt = 0;
270 SYSCTL_INT(_kern_sched_ipiwakeup, OID_AUTO, htt2, CTLFLAG_RW,
271 	   &forward_wakeup_use_htt, 0,
272 	   "account for htt");
273 
274 #endif
275 static int sched_followon = 0;
276 SYSCTL_INT(_kern_sched, OID_AUTO, followon, CTLFLAG_RW,
277 	   &sched_followon, 0,
278 	   "allow threads to share a quantum");
279 
280 static int sched_pfollowons = 0;
281 SYSCTL_INT(_kern_sched, OID_AUTO, pfollowons, CTLFLAG_RD,
282 	   &sched_pfollowons, 0,
283 	   "number of followons done to a different ksegrp");
284 
285 static int sched_kgfollowons = 0;
286 SYSCTL_INT(_kern_sched, OID_AUTO, kgfollowons, CTLFLAG_RD,
287 	   &sched_kgfollowons, 0,
288 	   "number of followons done in a ksegrp");
289 
290 static __inline void
291 sched_load_add(void)
292 {
293 	sched_tdcnt++;
294 	CTR1(KTR_SCHED, "global load: %d", sched_tdcnt);
295 }
296 
297 static __inline void
298 sched_load_rem(void)
299 {
300 	sched_tdcnt--;
301 	CTR1(KTR_SCHED, "global load: %d", sched_tdcnt);
302 }
303 /*
304  * Arrange to reschedule if necessary, taking the priorities and
305  * schedulers into account.
306  */
307 static void
308 maybe_resched(struct thread *td)
309 {
310 
311 	mtx_assert(&sched_lock, MA_OWNED);
312 	if (td->td_priority < curthread->td_priority)
313 		curthread->td_flags |= TDF_NEEDRESCHED;
314 }
315 
316 /*
317  * Force switch among equal priority processes every 100ms.
318  * We don't actually need to force a context switch of the current process.
319  * The act of firing the event triggers a context switch to softclock() and
320  * then switching back out again which is equivalent to a preemption, thus
321  * no further work is needed on the local CPU.
322  */
323 /* ARGSUSED */
324 static void
325 roundrobin(void *arg)
326 {
327 
328 #ifdef SMP
329 	mtx_lock_spin(&sched_lock);
330 	forward_roundrobin();
331 	mtx_unlock_spin(&sched_lock);
332 #endif
333 
334 	callout_reset(&roundrobin_callout, sched_quantum, roundrobin, NULL);
335 }
336 
337 /*
338  * Constants for digital decay and forget:
339  *	90% of (kg_estcpu) usage in 5 * loadav time
340  *	95% of (ke_pctcpu) usage in 60 seconds (load insensitive)
341  *          Note that, as ps(1) mentions, this can let percentages
342  *          total over 100% (I've seen 137.9% for 3 processes).
343  *
344  * Note that schedclock() updates kg_estcpu and p_cpticks asynchronously.
345  *
346  * We wish to decay away 90% of kg_estcpu in (5 * loadavg) seconds.
347  * That is, the system wants to compute a value of decay such
348  * that the following for loop:
349  * 	for (i = 0; i < (5 * loadavg); i++)
350  * 		kg_estcpu *= decay;
351  * will compute
352  * 	kg_estcpu *= 0.1;
353  * for all values of loadavg:
354  *
355  * Mathematically this loop can be expressed by saying:
356  * 	decay ** (5 * loadavg) ~= .1
357  *
358  * The system computes decay as:
359  * 	decay = (2 * loadavg) / (2 * loadavg + 1)
360  *
361  * We wish to prove that the system's computation of decay
362  * will always fulfill the equation:
363  * 	decay ** (5 * loadavg) ~= .1
364  *
365  * If we compute b as:
366  * 	b = 2 * loadavg
367  * then
368  * 	decay = b / (b + 1)
369  *
370  * We now need to prove two things:
371  *	1) Given factor ** (5 * loadavg) ~= .1, prove factor == b/(b+1)
372  *	2) Given b/(b+1) ** power ~= .1, prove power == (5 * loadavg)
373  *
374  * Facts:
375  *         For x close to zero, exp(x) =~ 1 + x, since
376  *              exp(x) = 0! + x**1/1! + x**2/2! + ... .
377  *              therefore exp(-1/b) =~ 1 - (1/b) = (b-1)/b.
378  *         For x close to zero, ln(1+x) =~ x, since
379  *              ln(1+x) = x - x**2/2 + x**3/3 - ...     -1 < x < 1
380  *              therefore ln(b/(b+1)) = ln(1 - 1/(b+1)) =~ -1/(b+1).
381  *         ln(.1) =~ -2.30
382  *
383  * Proof of (1):
384  *    Solve (factor)**(power) =~ .1 given power (5*loadav):
385  *	solving for factor,
386  *      ln(factor) =~ (-2.30/5*loadav), or
387  *      factor =~ exp(-1/((5/2.30)*loadav)) =~ exp(-1/(2*loadav)) =
388  *          exp(-1/b) =~ (b-1)/b =~ b/(b+1).                    QED
389  *
390  * Proof of (2):
391  *    Solve (factor)**(power) =~ .1 given factor == (b/(b+1)):
392  *	solving for power,
393  *      power*ln(b/(b+1)) =~ -2.30, or
394  *      power =~ 2.3 * (b + 1) = 4.6*loadav + 2.3 =~ 5*loadav.  QED
395  *
396  * Actual power values for the implemented algorithm are as follows:
397  *      loadav: 1       2       3       4
398  *      power:  5.68    10.32   14.94   19.55
399  */
400 
401 /* calculations for digital decay to forget 90% of usage in 5*loadav sec */
402 #define	loadfactor(loadav)	(2 * (loadav))
403 #define	decay_cpu(loadfac, cpu)	(((loadfac) * (cpu)) / ((loadfac) + FSCALE))
404 
405 /* decay 95% of `ke_pctcpu' in 60 seconds; see CCPU_SHIFT before changing */
406 static fixpt_t	ccpu = 0.95122942450071400909 * FSCALE;	/* exp(-1/20) */
407 SYSCTL_INT(_kern, OID_AUTO, ccpu, CTLFLAG_RD, &ccpu, 0, "");
408 
409 /*
410  * If `ccpu' is not equal to `exp(-1/20)' and you still want to use the
411  * faster/more-accurate formula, you'll have to estimate CCPU_SHIFT below
412  * and possibly adjust FSHIFT in "param.h" so that (FSHIFT >= CCPU_SHIFT).
413  *
414  * To estimate CCPU_SHIFT for exp(-1/20), the following formula was used:
415  *	1 - exp(-1/20) ~= 0.0487 ~= 0.0488 == 1 (fixed pt, *11* bits).
416  *
417  * If you don't want to bother with the faster/more-accurate formula, you
418  * can set CCPU_SHIFT to (FSHIFT + 1) which will use a slower/less-accurate
419  * (more general) method of calculating the %age of CPU used by a process.
420  */
421 #define	CCPU_SHIFT	11
422 
423 /*
424  * Recompute process priorities, every hz ticks.
425  * MP-safe, called without the Giant mutex.
426  */
427 /* ARGSUSED */
428 static void
429 schedcpu(void)
430 {
431 	register fixpt_t loadfac = loadfactor(averunnable.ldavg[0]);
432 	struct thread *td;
433 	struct proc *p;
434 	struct kse *ke;
435 	struct ksegrp *kg;
436 	int awake, realstathz;
437 
438 	realstathz = stathz ? stathz : hz;
439 	sx_slock(&allproc_lock);
440 	FOREACH_PROC_IN_SYSTEM(p) {
441 		/*
442 		 * Prevent state changes and protect run queue.
443 		 */
444 		mtx_lock_spin(&sched_lock);
445 		/*
446 		 * Increment time in/out of memory.  We ignore overflow; with
447 		 * 16-bit int's (remember them?) overflow takes 45 days.
448 		 */
449 		p->p_swtime++;
450 		FOREACH_KSEGRP_IN_PROC(p, kg) {
451 			awake = 0;
452 			FOREACH_THREAD_IN_GROUP(kg, td) {
453 				ke = td->td_kse;
454 				/*
455 				 * Increment sleep time (if sleeping).  We
456 				 * ignore overflow, as above.
457 				 */
458 				/*
459 				 * The kse slptimes are not touched in wakeup
460 				 * because the thread may not HAVE a KSE.
461 				 */
462 				if (ke->ke_state == KES_ONRUNQ) {
463 					awake = 1;
464 					ke->ke_flags &= ~KEF_DIDRUN;
465 				} else if ((ke->ke_state == KES_THREAD) &&
466 				    (TD_IS_RUNNING(td))) {
467 					awake = 1;
468 					/* Do not clear KEF_DIDRUN */
469 				} else if (ke->ke_flags & KEF_DIDRUN) {
470 					awake = 1;
471 					ke->ke_flags &= ~KEF_DIDRUN;
472 				}
473 
474 				/*
475 				 * ke_pctcpu is only for ps and ttyinfo().
476 				 * Do it per kse, and add them up at the end?
477 				 * XXXKSE
478 				 */
479 				ke->ke_pctcpu = (ke->ke_pctcpu * ccpu) >>
480 				    FSHIFT;
481 				/*
482 				 * If the kse has been idle the entire second,
483 				 * stop recalculating its priority until
484 				 * it wakes up.
485 				 */
486 				if (ke->ke_cpticks == 0)
487 					continue;
488 #if	(FSHIFT >= CCPU_SHIFT)
489 				ke->ke_pctcpu += (realstathz == 100)
490 				    ? ((fixpt_t) ke->ke_cpticks) <<
491 				    (FSHIFT - CCPU_SHIFT) :
492 				    100 * (((fixpt_t) ke->ke_cpticks)
493 				    << (FSHIFT - CCPU_SHIFT)) / realstathz;
494 #else
495 				ke->ke_pctcpu += ((FSCALE - ccpu) *
496 				    (ke->ke_cpticks *
497 				    FSCALE / realstathz)) >> FSHIFT;
498 #endif
499 				ke->ke_cpticks = 0;
500 			} /* end of kse loop */
501 			/*
502 			 * If there are ANY running threads in this KSEGRP,
503 			 * then don't count it as sleeping.
504 			 */
505 			if (awake) {
506 				if (kg->kg_slptime > 1) {
507 					/*
508 					 * In an ideal world, this should not
509 					 * happen, because whoever woke us
510 					 * up from the long sleep should have
511 					 * unwound the slptime and reset our
512 					 * priority before we run at the stale
513 					 * priority.  Should KASSERT at some
514 					 * point when all the cases are fixed.
515 					 */
516 					updatepri(kg);
517 				}
518 				kg->kg_slptime = 0;
519 			} else
520 				kg->kg_slptime++;
521 			if (kg->kg_slptime > 1)
522 				continue;
523 			kg->kg_estcpu = decay_cpu(loadfac, kg->kg_estcpu);
524 		      	resetpriority(kg);
525 			FOREACH_THREAD_IN_GROUP(kg, td) {
526 				resetpriority_thread(td, kg);
527 			}
528 		} /* end of ksegrp loop */
529 		mtx_unlock_spin(&sched_lock);
530 	} /* end of process loop */
531 	sx_sunlock(&allproc_lock);
532 }
533 
534 /*
535  * Main loop for a kthread that executes schedcpu once a second.
536  */
537 static void
538 schedcpu_thread(void)
539 {
540 	int nowake;
541 
542 	for (;;) {
543 		schedcpu();
544 		tsleep(&nowake, curthread->td_priority, "-", hz);
545 	}
546 }
547 
548 /*
549  * Recalculate the priority of a process after it has slept for a while.
550  * For all load averages >= 1 and max kg_estcpu of 255, sleeping for at
551  * least six times the loadfactor will decay kg_estcpu to zero.
552  */
553 static void
554 updatepri(struct ksegrp *kg)
555 {
556 	register fixpt_t loadfac;
557 	register unsigned int newcpu;
558 
559 	loadfac = loadfactor(averunnable.ldavg[0]);
560 	if (kg->kg_slptime > 5 * loadfac)
561 		kg->kg_estcpu = 0;
562 	else {
563 		newcpu = kg->kg_estcpu;
564 		kg->kg_slptime--;	/* was incremented in schedcpu() */
565 		while (newcpu && --kg->kg_slptime)
566 			newcpu = decay_cpu(loadfac, newcpu);
567 		kg->kg_estcpu = newcpu;
568 	}
569 }
570 
571 /*
572  * Compute the priority of a process when running in user mode.
573  * Arrange to reschedule if the resulting priority is better
574  * than that of the current process.
575  */
576 static void
577 resetpriority(struct ksegrp *kg)
578 {
579 	register unsigned int newpriority;
580 
581 	if (kg->kg_pri_class == PRI_TIMESHARE) {
582 		newpriority = PUSER + kg->kg_estcpu / INVERSE_ESTCPU_WEIGHT +
583 		    NICE_WEIGHT * (kg->kg_proc->p_nice - PRIO_MIN);
584 		newpriority = min(max(newpriority, PRI_MIN_TIMESHARE),
585 		    PRI_MAX_TIMESHARE);
586 		kg->kg_user_pri = newpriority;
587 	}
588 }
589 
590 /*
591  * Update the thread's priority when the associated ksegroup's user
592  * priority changes.
593  */
594 static void
595 resetpriority_thread(struct thread *td, struct ksegrp *kg)
596 {
597 
598 	/* Only change threads with a time sharing user priority. */
599 	if (td->td_priority < PRI_MIN_TIMESHARE ||
600 	    td->td_priority > PRI_MAX_TIMESHARE)
601 		return;
602 
603 	/* XXX the whole needresched thing is broken, but not silly. */
604 	maybe_resched(td);
605 
606 	sched_prio(td, kg->kg_user_pri);
607 }
608 
609 /* ARGSUSED */
610 static void
611 sched_setup(void *dummy)
612 {
613 	setup_runqs();
614 
615 	if (sched_quantum == 0)
616 		sched_quantum = SCHED_QUANTUM;
617 	hogticks = 2 * sched_quantum;
618 
619 	callout_init(&roundrobin_callout, CALLOUT_MPSAFE);
620 
621 	/* Kick off timeout driven events by calling first time. */
622 	roundrobin(NULL);
623 
624 	/* Account for thread0. */
625 	sched_load_add();
626 }
627 
628 /* External interfaces start here */
629 /*
630  * Very early in the boot some setup of scheduler-specific
631  * parts of proc0 and of some scheduler resources needs to be done.
632  * Called from:
633  *  proc0_init()
634  */
635 void
636 schedinit(void)
637 {
638 	/*
639 	 * Set up the scheduler specific parts of proc0.
640 	 */
641 	proc0.p_sched = NULL; /* XXX */
642 	ksegrp0.kg_sched = &kg_sched0;
643 	thread0.td_sched = &kse0;
644 	kse0.ke_thread = &thread0;
645 	kse0.ke_state = KES_THREAD;
646 	kg_sched0.skg_concurrency = 1;
647 	kg_sched0.skg_avail_opennings = 0; /* we are already running */
648 }
649 
650 int
651 sched_runnable(void)
652 {
653 #ifdef SMP
654 	return runq_check(&runq) + runq_check(&runq_pcpu[PCPU_GET(cpuid)]);
655 #else
656 	return runq_check(&runq);
657 #endif
658 }
659 
660 int
661 sched_rr_interval(void)
662 {
663 	if (sched_quantum == 0)
664 		sched_quantum = SCHED_QUANTUM;
665 	return (sched_quantum);
666 }
667 
668 /*
669  * We adjust the priority of the current process.  The priority of
670  * a process gets worse as it accumulates CPU time.  The cpu usage
671  * estimator (kg_estcpu) is increased here.  resetpriority() will
672  * compute a different priority each time kg_estcpu increases by
673  * INVERSE_ESTCPU_WEIGHT
674  * (until MAXPRI is reached).  The cpu usage estimator ramps up
675  * quite quickly when the process is running (linearly), and decays
676  * away exponentially, at a rate which is proportionally slower when
677  * the system is busy.  The basic principle is that the system will
678  * 90% forget that the process used a lot of CPU time in 5 * loadav
679  * seconds.  This causes the system to favor processes which haven't
680  * run much recently, and to round-robin among other processes.
681  */
682 void
683 sched_clock(struct thread *td)
684 {
685 	struct ksegrp *kg;
686 	struct kse *ke;
687 
688 	mtx_assert(&sched_lock, MA_OWNED);
689 	kg = td->td_ksegrp;
690 	ke = td->td_kse;
691 
692 	ke->ke_cpticks++;
693 	kg->kg_estcpu = ESTCPULIM(kg->kg_estcpu + 1);
694 	if ((kg->kg_estcpu % INVERSE_ESTCPU_WEIGHT) == 0) {
695 		resetpriority(kg);
696 		resetpriority_thread(td, kg);
697 	}
698 }
699 
700 /*
701  * charge childs scheduling cpu usage to parent.
702  *
703  * XXXKSE assume only one thread & kse & ksegrp keep estcpu in each ksegrp.
704  * Charge it to the ksegrp that did the wait since process estcpu is sum of
705  * all ksegrps, this is strictly as expected.  Assume that the child process
706  * aggregated all the estcpu into the 'built-in' ksegrp.
707  */
708 void
709 sched_exit(struct proc *p, struct thread *td)
710 {
711 	sched_exit_ksegrp(FIRST_KSEGRP_IN_PROC(p), td);
712 	sched_exit_thread(FIRST_THREAD_IN_PROC(p), td);
713 }
714 
715 void
716 sched_exit_ksegrp(struct ksegrp *kg, struct thread *childtd)
717 {
718 
719 	mtx_assert(&sched_lock, MA_OWNED);
720 	kg->kg_estcpu = ESTCPULIM(kg->kg_estcpu + childtd->td_ksegrp->kg_estcpu);
721 }
722 
723 void
724 sched_exit_thread(struct thread *td, struct thread *child)
725 {
726 	CTR3(KTR_SCHED, "sched_exit_thread: %p(%s) prio %d",
727 	    child, child->td_proc->p_comm, child->td_priority);
728 	if ((child->td_proc->p_flag & P_NOLOAD) == 0)
729 		sched_load_rem();
730 }
731 
732 void
733 sched_fork(struct thread *td, struct thread *childtd)
734 {
735 	sched_fork_ksegrp(td, childtd->td_ksegrp);
736 	sched_fork_thread(td, childtd);
737 }
738 
739 void
740 sched_fork_ksegrp(struct thread *td, struct ksegrp *child)
741 {
742 	mtx_assert(&sched_lock, MA_OWNED);
743 	child->kg_estcpu = td->td_ksegrp->kg_estcpu;
744 }
745 
746 void
747 sched_fork_thread(struct thread *td, struct thread *childtd)
748 {
749 	sched_newthread(childtd);
750 }
751 
752 void
753 sched_nice(struct proc *p, int nice)
754 {
755 	struct ksegrp *kg;
756 	struct thread *td;
757 
758 	PROC_LOCK_ASSERT(p, MA_OWNED);
759 	mtx_assert(&sched_lock, MA_OWNED);
760 	p->p_nice = nice;
761 	FOREACH_KSEGRP_IN_PROC(p, kg) {
762 		resetpriority(kg);
763 		FOREACH_THREAD_IN_GROUP(kg, td) {
764 			resetpriority_thread(td, kg);
765 		}
766 	}
767 }
768 
769 void
770 sched_class(struct ksegrp *kg, int class)
771 {
772 	mtx_assert(&sched_lock, MA_OWNED);
773 	kg->kg_pri_class = class;
774 }
775 
776 /*
777  * Adjust the priority of a thread.
778  * This may include moving the thread within the KSEGRP,
779  * changing the assignment of a kse to the thread,
780  * and moving a KSE in the system run queue.
781  */
782 static void
783 sched_priority(struct thread *td, u_char prio)
784 {
785 	CTR6(KTR_SCHED, "sched_prio: %p(%s) prio %d newprio %d by %p(%s)",
786 	    td, td->td_proc->p_comm, td->td_priority, prio, curthread,
787 	    curthread->td_proc->p_comm);
788 
789 	mtx_assert(&sched_lock, MA_OWNED);
790 	if (td->td_priority == prio)
791 		return;
792 	if (TD_ON_RUNQ(td)) {
793 		adjustrunqueue(td, prio);
794 	} else {
795 		td->td_priority = prio;
796 	}
797 }
798 
799 /*
800  * Update a thread's priority when it is lent another thread's
801  * priority.
802  */
803 void
804 sched_lend_prio(struct thread *td, u_char prio)
805 {
806 
807 	td->td_flags |= TDF_BORROWING;
808 	sched_priority(td, prio);
809 }
810 
811 /*
812  * Restore a thread's priority when priority propagation is
813  * over.  The prio argument is the minimum priority the thread
814  * needs to have to satisfy other possible priority lending
815  * requests.  If the thread's regulary priority is less
816  * important than prio the thread will keep a priority boost
817  * of prio.
818  */
819 void
820 sched_unlend_prio(struct thread *td, u_char prio)
821 {
822 	u_char base_pri;
823 
824 	if (td->td_base_pri >= PRI_MIN_TIMESHARE &&
825 	    td->td_base_pri <= PRI_MAX_TIMESHARE)
826 		base_pri = td->td_ksegrp->kg_user_pri;
827 	else
828 		base_pri = td->td_base_pri;
829 	if (prio >= base_pri) {
830 		td->td_flags &= ~TDF_BORROWING;
831 		sched_prio(td, base_pri);
832 	} else
833 		sched_lend_prio(td, prio);
834 }
835 
836 void
837 sched_prio(struct thread *td, u_char prio)
838 {
839 	u_char oldprio;
840 
841 	/* First, update the base priority. */
842 	td->td_base_pri = prio;
843 
844 	/*
845 	 * If the thread is borrowing another thread's priority, don't ever
846 	 * lower the priority.
847 	 */
848 	if (td->td_flags & TDF_BORROWING && td->td_priority < prio)
849 		return;
850 
851 	/* Change the real priority. */
852 	oldprio = td->td_priority;
853 	sched_priority(td, prio);
854 
855 	/*
856 	 * If the thread is on a turnstile, then let the turnstile update
857 	 * its state.
858 	 */
859 	if (TD_ON_LOCK(td) && oldprio != prio)
860 		turnstile_adjust(td, oldprio);
861 }
862 
863 void
864 sched_sleep(struct thread *td)
865 {
866 
867 	mtx_assert(&sched_lock, MA_OWNED);
868 	td->td_ksegrp->kg_slptime = 0;
869 }
870 
871 static void remrunqueue(struct thread *td);
872 
873 void
874 sched_switch(struct thread *td, struct thread *newtd, int flags)
875 {
876 	struct kse *ke;
877 	struct ksegrp *kg;
878 	struct proc *p;
879 
880 	ke = td->td_kse;
881 	p = td->td_proc;
882 
883 	mtx_assert(&sched_lock, MA_OWNED);
884 
885 	if ((p->p_flag & P_NOLOAD) == 0)
886 		sched_load_rem();
887 	/*
888 	 * We are volunteering to switch out so we get to nominate
889 	 * a successor for the rest of our quantum
890 	 * First try another thread in our ksegrp, and then look for
891 	 * other ksegrps in our process.
892 	 */
893 	if (sched_followon &&
894 	    (p->p_flag & P_HADTHREADS) &&
895 	    (flags & SW_VOL) &&
896 	    newtd == NULL) {
897 		/* lets schedule another thread from this process */
898 		 kg = td->td_ksegrp;
899 		 if ((newtd = TAILQ_FIRST(&kg->kg_runq))) {
900 			remrunqueue(newtd);
901 			sched_kgfollowons++;
902 		 } else {
903 			FOREACH_KSEGRP_IN_PROC(p, kg) {
904 				if ((newtd = TAILQ_FIRST(&kg->kg_runq))) {
905 					sched_pfollowons++;
906 					remrunqueue(newtd);
907 					break;
908 				}
909 			}
910 		}
911 	}
912 
913 	if (newtd)
914 		newtd->td_flags |= (td->td_flags & TDF_NEEDRESCHED);
915 
916 	td->td_lastcpu = td->td_oncpu;
917 	td->td_flags &= ~TDF_NEEDRESCHED;
918 	td->td_owepreempt = 0;
919 	td->td_oncpu = NOCPU;
920 	/*
921 	 * At the last moment, if this thread is still marked RUNNING,
922 	 * then put it back on the run queue as it has not been suspended
923 	 * or stopped or any thing else similar.  We never put the idle
924 	 * threads on the run queue, however.
925 	 */
926 	if (td == PCPU_GET(idlethread))
927 		TD_SET_CAN_RUN(td);
928 	else {
929 		SLOT_RELEASE(td->td_ksegrp);
930 		if (TD_IS_RUNNING(td)) {
931 			/* Put us back on the run queue (kse and all). */
932 			setrunqueue(td, (flags & SW_PREEMPT) ?
933 			    SRQ_OURSELF|SRQ_YIELDING|SRQ_PREEMPTED :
934 			    SRQ_OURSELF|SRQ_YIELDING);
935 		} else if (p->p_flag & P_HADTHREADS) {
936 			/*
937 			 * We will not be on the run queue. So we must be
938 			 * sleeping or similar. As it's available,
939 			 * someone else can use the KSE if they need it.
940 			 * It's NOT available if we are about to need it
941 			 */
942 			if (newtd == NULL || newtd->td_ksegrp != td->td_ksegrp)
943 				slot_fill(td->td_ksegrp);
944 		}
945 	}
946 	if (newtd) {
947 		/*
948 		 * The thread we are about to run needs to be counted
949 		 * as if it had been added to the run queue and selected.
950 		 * It came from:
951 		 * * A preemption
952 		 * * An upcall
953 		 * * A followon
954 		 */
955 		KASSERT((newtd->td_inhibitors == 0),
956 			("trying to run inhibitted thread"));
957 		SLOT_USE(newtd->td_ksegrp);
958 		newtd->td_kse->ke_flags |= KEF_DIDRUN;
959         	TD_SET_RUNNING(newtd);
960 		if ((newtd->td_proc->p_flag & P_NOLOAD) == 0)
961 			sched_load_add();
962 	} else {
963 		newtd = choosethread();
964 	}
965 
966 	if (td != newtd) {
967 #ifdef	HWPMC_HOOKS
968 		if (PMC_PROC_IS_USING_PMCS(td->td_proc))
969 			PMC_SWITCH_CONTEXT(td, PMC_FN_CSW_OUT);
970 #endif
971 		cpu_switch(td, newtd);
972 #ifdef	HWPMC_HOOKS
973 		if (PMC_PROC_IS_USING_PMCS(td->td_proc))
974 			PMC_SWITCH_CONTEXT(td, PMC_FN_CSW_IN);
975 #endif
976 	}
977 
978 	sched_lock.mtx_lock = (uintptr_t)td;
979 	td->td_oncpu = PCPU_GET(cpuid);
980 }
981 
982 void
983 sched_wakeup(struct thread *td)
984 {
985 	struct ksegrp *kg;
986 
987 	mtx_assert(&sched_lock, MA_OWNED);
988 	kg = td->td_ksegrp;
989 	if (kg->kg_slptime > 1) {
990 		updatepri(kg);
991 		resetpriority(kg);
992 	}
993 	kg->kg_slptime = 0;
994 	setrunqueue(td, SRQ_BORING);
995 }
996 
997 #ifdef SMP
998 /* enable HTT_2 if you have a 2-way HTT cpu.*/
999 static int
1000 forward_wakeup(int  cpunum)
1001 {
1002 	cpumask_t map, me, dontuse;
1003 	cpumask_t map2;
1004 	struct pcpu *pc;
1005 	cpumask_t id, map3;
1006 
1007 	mtx_assert(&sched_lock, MA_OWNED);
1008 
1009 	CTR0(KTR_RUNQ, "forward_wakeup()");
1010 
1011 	if ((!forward_wakeup_enabled) ||
1012 	     (forward_wakeup_use_mask == 0 && forward_wakeup_use_loop == 0))
1013 		return (0);
1014 	if (!smp_started || cold || panicstr)
1015 		return (0);
1016 
1017 	forward_wakeups_requested++;
1018 
1019 /*
1020  * check the idle mask we received against what we calculated before
1021  * in the old version.
1022  */
1023 	me = PCPU_GET(cpumask);
1024 	/*
1025 	 * don't bother if we should be doing it ourself..
1026 	 */
1027 	if ((me & idle_cpus_mask) && (cpunum == NOCPU || me == (1 << cpunum)))
1028 		return (0);
1029 
1030 	dontuse = me | stopped_cpus | hlt_cpus_mask;
1031 	map3 = 0;
1032 	if (forward_wakeup_use_loop) {
1033 		SLIST_FOREACH(pc, &cpuhead, pc_allcpu) {
1034 			id = pc->pc_cpumask;
1035 			if ( (id & dontuse) == 0 &&
1036 			    pc->pc_curthread == pc->pc_idlethread) {
1037 				map3 |= id;
1038 			}
1039 		}
1040 	}
1041 
1042 	if (forward_wakeup_use_mask) {
1043 		map = 0;
1044 		map = idle_cpus_mask & ~dontuse;
1045 
1046 		/* If they are both on, compare and use loop if different */
1047 		if (forward_wakeup_use_loop) {
1048 			if (map != map3) {
1049 				printf("map (%02X) != map3 (%02X)\n",
1050 						map, map3);
1051 				map = map3;
1052 			}
1053 		}
1054 	} else {
1055 		map = map3;
1056 	}
1057 	/* If we only allow a specific CPU, then mask off all the others */
1058 	if (cpunum != NOCPU) {
1059 		KASSERT((cpunum <= mp_maxcpus),("forward_wakeup: bad cpunum."));
1060 		map &= (1 << cpunum);
1061 	} else {
1062 		/* Try choose an idle die. */
1063 		if (forward_wakeup_use_htt) {
1064 			map2 =  (map & (map >> 1)) & 0x5555;
1065 			if (map2) {
1066 				map = map2;
1067 			}
1068 		}
1069 
1070 		/* set only one bit */
1071 		if (forward_wakeup_use_single) {
1072 			map = map & ((~map) + 1);
1073 		}
1074 	}
1075 	if (map) {
1076 		forward_wakeups_delivered++;
1077 		ipi_selected(map, IPI_AST);
1078 		return (1);
1079 	}
1080 	if (cpunum == NOCPU)
1081 		printf("forward_wakeup: Idle processor not found\n");
1082 	return (0);
1083 }
1084 #endif
1085 
1086 void
1087 sched_add(struct thread *td, int flags)
1088 {
1089 	struct kse *ke;
1090 #ifdef SMP
1091 	int forwarded = 0;
1092 	int cpu;
1093 #endif
1094 
1095 	ke = td->td_kse;
1096 	mtx_assert(&sched_lock, MA_OWNED);
1097 	KASSERT(ke->ke_state != KES_ONRUNQ,
1098 	    ("sched_add: kse %p (%s) already in run queue", ke,
1099 	    ke->ke_proc->p_comm));
1100 	KASSERT(ke->ke_proc->p_sflag & PS_INMEM,
1101 	    ("sched_add: process swapped out"));
1102 	CTR5(KTR_SCHED, "sched_add: %p(%s) prio %d by %p(%s)",
1103 	    td, td->td_proc->p_comm, td->td_priority, curthread,
1104 	    curthread->td_proc->p_comm);
1105 
1106 #ifdef SMP
1107 	if (KSE_CAN_MIGRATE(ke)) {
1108 		CTR2(KTR_RUNQ,
1109 		    "sched_add: adding kse:%p (td:%p) to gbl runq", ke, td);
1110 		cpu = NOCPU;
1111 		ke->ke_runq = &runq;
1112 	} else {
1113 		if (!SKE_RUNQ_PCPU(ke))
1114 			ke->ke_runq = &runq_pcpu[(cpu = PCPU_GET(cpuid))];
1115 		else
1116 			cpu = td->td_lastcpu;
1117 		CTR3(KTR_RUNQ,
1118 		    "sched_add: Put kse:%p(td:%p) on cpu%d runq", ke, td, cpu);
1119 	}
1120 #else
1121 	CTR2(KTR_RUNQ, "sched_add: adding kse:%p (td:%p) to runq", ke, td);
1122 	ke->ke_runq = &runq;
1123 
1124 #endif
1125 	/*
1126 	 * If we are yielding (on the way out anyhow)
1127 	 * or the thread being saved is US,
1128 	 * then don't try be smart about preemption
1129 	 * or kicking off another CPU
1130 	 * as it won't help and may hinder.
1131 	 * In the YIEDLING case, we are about to run whoever is
1132 	 * being put in the queue anyhow, and in the
1133 	 * OURSELF case, we are puting ourself on the run queue
1134 	 * which also only happens when we are about to yield.
1135 	 */
1136 	if((flags & SRQ_YIELDING) == 0) {
1137 #ifdef SMP
1138 		cpumask_t me = PCPU_GET(cpumask);
1139 		int idle = idle_cpus_mask & me;
1140 		/*
1141 		 * Only try to kick off another CPU if
1142 		 * the thread is unpinned
1143 		 * or pinned to another cpu,
1144 		 * and there are other available and idle CPUs.
1145 		 * if we are idle, or it's an interrupt,
1146 		 * then skip straight to preemption.
1147 		 */
1148 		if ( (! idle) && ((flags & SRQ_INTR) == 0) &&
1149 		    (idle_cpus_mask & ~(hlt_cpus_mask | me)) &&
1150 		    ( KSE_CAN_MIGRATE(ke) ||
1151 		      ke->ke_runq != &runq_pcpu[PCPU_GET(cpuid)])) {
1152 			forwarded = forward_wakeup(cpu);
1153 		}
1154 		/*
1155 		 * If we failed to kick off another cpu, then look to
1156 		 * see if we should preempt this CPU. Only allow this
1157 		 * if it is not pinned or IS pinned to this CPU.
1158 		 * If we are the idle thread, we also try do preempt.
1159 		 * as it will be quicker and being idle, we won't
1160 		 * lose in doing so..
1161 		 */
1162 		if ((!forwarded) &&
1163 		    (ke->ke_runq == &runq ||
1164 		     ke->ke_runq == &runq_pcpu[PCPU_GET(cpuid)]))
1165 #endif
1166 
1167 		{
1168 			if (maybe_preempt(td))
1169 				return;
1170 		}
1171 	}
1172 	if ((td->td_proc->p_flag & P_NOLOAD) == 0)
1173 		sched_load_add();
1174 	SLOT_USE(td->td_ksegrp);
1175 	runq_add(ke->ke_runq, ke, flags);
1176 	ke->ke_state = KES_ONRUNQ;
1177 	maybe_resched(td);
1178 }
1179 
1180 void
1181 sched_rem(struct thread *td)
1182 {
1183 	struct kse *ke;
1184 
1185 	ke = td->td_kse;
1186 	KASSERT(ke->ke_proc->p_sflag & PS_INMEM,
1187 	    ("sched_rem: process swapped out"));
1188 	KASSERT((ke->ke_state == KES_ONRUNQ),
1189 	    ("sched_rem: KSE not on run queue"));
1190 	mtx_assert(&sched_lock, MA_OWNED);
1191 	CTR5(KTR_SCHED, "sched_rem: %p(%s) prio %d by %p(%s)",
1192 	    td, td->td_proc->p_comm, td->td_priority, curthread,
1193 	    curthread->td_proc->p_comm);
1194 
1195 	if ((td->td_proc->p_flag & P_NOLOAD) == 0)
1196 		sched_load_rem();
1197 	SLOT_RELEASE(td->td_ksegrp);
1198 	runq_remove(ke->ke_runq, ke);
1199 
1200 	ke->ke_state = KES_THREAD;
1201 }
1202 
1203 /*
1204  * Select threads to run.
1205  * Notice that the running threads still consume a slot.
1206  */
1207 struct kse *
1208 sched_choose(void)
1209 {
1210 	struct kse *ke;
1211 	struct runq *rq;
1212 
1213 #ifdef SMP
1214 	struct kse *kecpu;
1215 
1216 	rq = &runq;
1217 	ke = runq_choose(&runq);
1218 	kecpu = runq_choose(&runq_pcpu[PCPU_GET(cpuid)]);
1219 
1220 	if (ke == NULL ||
1221 	    (kecpu != NULL &&
1222 	     kecpu->ke_thread->td_priority < ke->ke_thread->td_priority)) {
1223 		CTR2(KTR_RUNQ, "choosing kse %p from pcpu runq %d", kecpu,
1224 		     PCPU_GET(cpuid));
1225 		ke = kecpu;
1226 		rq = &runq_pcpu[PCPU_GET(cpuid)];
1227 	} else {
1228 		CTR1(KTR_RUNQ, "choosing kse %p from main runq", ke);
1229 	}
1230 
1231 #else
1232 	rq = &runq;
1233 	ke = runq_choose(&runq);
1234 #endif
1235 
1236 	if (ke != NULL) {
1237 		runq_remove(rq, ke);
1238 		ke->ke_state = KES_THREAD;
1239 
1240 		KASSERT(ke->ke_proc->p_sflag & PS_INMEM,
1241 		    ("sched_choose: process swapped out"));
1242 	}
1243 	return (ke);
1244 }
1245 
1246 void
1247 sched_userret(struct thread *td)
1248 {
1249 	struct ksegrp *kg;
1250 	/*
1251 	 * XXX we cheat slightly on the locking here to avoid locking in
1252 	 * the usual case.  Setting td_priority here is essentially an
1253 	 * incomplete workaround for not setting it properly elsewhere.
1254 	 * Now that some interrupt handlers are threads, not setting it
1255 	 * properly elsewhere can clobber it in the window between setting
1256 	 * it here and returning to user mode, so don't waste time setting
1257 	 * it perfectly here.
1258 	 */
1259 	KASSERT((td->td_flags & TDF_BORROWING) == 0,
1260 	    ("thread with borrowed priority returning to userland"));
1261 	kg = td->td_ksegrp;
1262 	if (td->td_priority != kg->kg_user_pri) {
1263 		mtx_lock_spin(&sched_lock);
1264 		td->td_priority = kg->kg_user_pri;
1265 		td->td_base_pri = kg->kg_user_pri;
1266 		mtx_unlock_spin(&sched_lock);
1267 	}
1268 }
1269 
1270 void
1271 sched_bind(struct thread *td, int cpu)
1272 {
1273 	struct kse *ke;
1274 
1275 	mtx_assert(&sched_lock, MA_OWNED);
1276 	KASSERT(TD_IS_RUNNING(td),
1277 	    ("sched_bind: cannot bind non-running thread"));
1278 
1279 	ke = td->td_kse;
1280 
1281 	ke->ke_flags |= KEF_BOUND;
1282 #ifdef SMP
1283 	ke->ke_runq = &runq_pcpu[cpu];
1284 	if (PCPU_GET(cpuid) == cpu)
1285 		return;
1286 
1287 	ke->ke_state = KES_THREAD;
1288 
1289 	mi_switch(SW_VOL, NULL);
1290 #endif
1291 }
1292 
1293 void
1294 sched_unbind(struct thread* td)
1295 {
1296 	mtx_assert(&sched_lock, MA_OWNED);
1297 	td->td_kse->ke_flags &= ~KEF_BOUND;
1298 }
1299 
1300 int
1301 sched_is_bound(struct thread *td)
1302 {
1303 	mtx_assert(&sched_lock, MA_OWNED);
1304 	return (td->td_kse->ke_flags & KEF_BOUND);
1305 }
1306 
1307 int
1308 sched_load(void)
1309 {
1310 	return (sched_tdcnt);
1311 }
1312 
1313 int
1314 sched_sizeof_ksegrp(void)
1315 {
1316 	return (sizeof(struct ksegrp) + sizeof(struct kg_sched));
1317 }
1318 int
1319 sched_sizeof_proc(void)
1320 {
1321 	return (sizeof(struct proc));
1322 }
1323 int
1324 sched_sizeof_thread(void)
1325 {
1326 	return (sizeof(struct thread) + sizeof(struct kse));
1327 }
1328 
1329 fixpt_t
1330 sched_pctcpu(struct thread *td)
1331 {
1332 	struct kse *ke;
1333 
1334 	ke = td->td_kse;
1335 	return (ke->ke_pctcpu);
1336 
1337 	return (0);
1338 }
1339 #define KERN_SWITCH_INCLUDE 1
1340 #include "kern/kern_switch.c"
1341