FreeBSD kernel kern code
kern_synch.c
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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 * @(#)kern_synch.c 8.9 (Berkeley) 5/19/95
37 */
38
39#include <sys/cdefs.h>
40__FBSDID("$FreeBSD$");
41
42#include "opt_ktrace.h"
43#include "opt_sched.h"
44
45#include <sys/param.h>
46#include <sys/systm.h>
47#include <sys/blockcount.h>
48#include <sys/condvar.h>
49#include <sys/kdb.h>
50#include <sys/kernel.h>
51#include <sys/ktr.h>
52#include <sys/lock.h>
53#include <sys/mutex.h>
54#include <sys/proc.h>
55#include <sys/resourcevar.h>
56#include <sys/sched.h>
57#include <sys/sdt.h>
58#include <sys/signalvar.h>
59#include <sys/sleepqueue.h>
60#include <sys/smp.h>
61#include <sys/sx.h>
62#include <sys/sysctl.h>
63#include <sys/sysproto.h>
64#include <sys/vmmeter.h>
65#ifdef KTRACE
66#include <sys/uio.h>
67#include <sys/ktrace.h>
68#endif
69#ifdef EPOCH_TRACE
70#include <sys/epoch.h>
71#endif
72
73#include <machine/cpu.h>
74
75static void synch_setup(void *dummy);
76SYSINIT(synch_setup, SI_SUB_KICK_SCHEDULER, SI_ORDER_FIRST, synch_setup,
77 NULL);
78
80static const char pause_wchan[MAXCPU];
81
82static struct callout loadav_callout;
83
84struct loadavg averunnable =
85 { {0, 0, 0}, FSCALE }; /* load average, of runnable procs */
86/*
87 * Constants for averages over 1, 5, and 15 minutes
88 * when sampling at 5 second intervals.
89 */
90static fixpt_t cexp[3] = {
91 0.9200444146293232 * FSCALE, /* exp(-1/12) */
92 0.9834714538216174 * FSCALE, /* exp(-1/60) */
93 0.9944598480048967 * FSCALE, /* exp(-1/180) */
94};
95
96/* kernel uses `FSCALE', userland (SHOULD) use kern.fscale */
97SYSCTL_INT(_kern, OID_AUTO, fscale, CTLFLAG_RD, SYSCTL_NULL_INT_PTR, FSCALE,
98 "Fixed-point scale factor used for calculating load average values");
99
100static void loadav(void *arg);
101
103SDT_PROBE_DEFINE(sched, , , preempt);
104
105static void
106sleepinit(void *unused)
107{
108
109 hogticks = (hz / 10) * 2; /* Default only. */
111}
112
113/*
114 * vmem tries to lock the sleepq mutexes when free'ing kva, so make sure
115 * it is available.
116 */
117SYSINIT(sleepinit, SI_SUB_KMEM, SI_ORDER_ANY, sleepinit, NULL);
118
119/*
120 * General sleep call. Suspends the current thread until a wakeup is
121 * performed on the specified identifier. The thread will then be made
122 * runnable with the specified priority. Sleeps at most sbt units of time
123 * (0 means no timeout). If pri includes the PCATCH flag, let signals
124 * interrupt the sleep, otherwise ignore them while sleeping. Returns 0 if
125 * awakened, EWOULDBLOCK if the timeout expires. If PCATCH is set and a
126 * signal becomes pending, ERESTART is returned if the current system
127 * call should be restarted if possible, and EINTR is returned if the system
128 * call should be interrupted by the signal (return EINTR).
129 *
130 * The lock argument is unlocked before the caller is suspended, and
131 * re-locked before _sleep() returns. If priority includes the PDROP
132 * flag the lock is not re-locked before returning.
133 */
134int
135_sleep(const void *ident, struct lock_object *lock, int priority,
136 const char *wmesg, sbintime_t sbt, sbintime_t pr, int flags)
137{
138 struct thread *td;
139 struct lock_class *class;
140 uintptr_t lock_state;
141 int catch, pri, rval, sleepq_flags;
142 WITNESS_SAVE_DECL(lock_witness);
143
144 TSENTER();
145 td = curthread;
146#ifdef KTRACE
147 if (KTRPOINT(td, KTR_CSW))
148 ktrcsw(1, 0, wmesg);
149#endif
150 WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, lock,
151 "Sleeping on \"%s\"", wmesg);
152 KASSERT(sbt != 0 || mtx_owned(&Giant) || lock != NULL ||
153 (priority & PNOLOCK) != 0,
154 ("sleeping without a lock"));
155 KASSERT(ident != NULL, ("_sleep: NULL ident"));
156 KASSERT(TD_IS_RUNNING(td), ("_sleep: curthread not running"));
157 if (priority & PDROP)
158 KASSERT(lock != NULL && lock != &Giant.lock_object,
159 ("PDROP requires a non-Giant lock"));
160 if (lock != NULL)
161 class = LOCK_CLASS(lock);
162 else
163 class = NULL;
164
165 if (SCHEDULER_STOPPED_TD(td)) {
166 if (lock != NULL && priority & PDROP)
167 class->lc_unlock(lock);
168 return (0);
169 }
170 catch = priority & PCATCH;
171 pri = priority & PRIMASK;
172
173 KASSERT(!TD_ON_SLEEPQ(td), ("recursive sleep"));
174
175 if ((uintptr_t)ident >= (uintptr_t)&pause_wchan[0] &&
176 (uintptr_t)ident <= (uintptr_t)&pause_wchan[MAXCPU - 1])
177 sleepq_flags = SLEEPQ_PAUSE;
178 else
179 sleepq_flags = SLEEPQ_SLEEP;
180 if (catch)
181 sleepq_flags |= SLEEPQ_INTERRUPTIBLE;
182
183 sleepq_lock(ident);
184 CTR5(KTR_PROC, "sleep: thread %ld (pid %ld, %s) on %s (%p)",
185 td->td_tid, td->td_proc->p_pid, td->td_name, wmesg, ident);
186
187 if (lock == &Giant.lock_object)
188 mtx_assert(&Giant, MA_OWNED);
189 DROP_GIANT();
190 if (lock != NULL && lock != &Giant.lock_object &&
191 !(class->lc_flags & LC_SLEEPABLE)) {
192 KASSERT(!(class->lc_flags & LC_SPINLOCK),
193 ("spin locks can only use msleep_spin"));
194 WITNESS_SAVE(lock, lock_witness);
195 lock_state = class->lc_unlock(lock);
196 } else
197 /* GCC needs to follow the Yellow Brick Road */
198 lock_state = -1;
199
200 /*
201 * We put ourselves on the sleep queue and start our timeout
202 * before calling thread_suspend_check, as we could stop there,
203 * and a wakeup or a SIGCONT (or both) could occur while we were
204 * stopped without resuming us. Thus, we must be ready for sleep
205 * when cursig() is called. If the wakeup happens while we're
206 * stopped, then td will no longer be on a sleep queue upon
207 * return from cursig().
208 */
209 sleepq_add(ident, lock, wmesg, sleepq_flags, 0);
210 if (sbt != 0)
211 sleepq_set_timeout_sbt(ident, sbt, pr, flags);
212 if (lock != NULL && class->lc_flags & LC_SLEEPABLE) {
213 sleepq_release(ident);
214 WITNESS_SAVE(lock, lock_witness);
215 lock_state = class->lc_unlock(lock);
216 sleepq_lock(ident);
217 }
218 if (sbt != 0 && catch)
219 rval = sleepq_timedwait_sig(ident, pri);
220 else if (sbt != 0)
221 rval = sleepq_timedwait(ident, pri);
222 else if (catch)
223 rval = sleepq_wait_sig(ident, pri);
224 else {
225 sleepq_wait(ident, pri);
226 rval = 0;
227 }
228#ifdef KTRACE
229 if (KTRPOINT(td, KTR_CSW))
230 ktrcsw(0, 0, wmesg);
231#endif
232 PICKUP_GIANT();
233 if (lock != NULL && lock != &Giant.lock_object && !(priority & PDROP)) {
234 class->lc_lock(lock, lock_state);
235 WITNESS_RESTORE(lock, lock_witness);
236 }
237 TSEXIT();
238 return (rval);
239}
240
241int
242msleep_spin_sbt(const void *ident, struct mtx *mtx, const char *wmesg,
243 sbintime_t sbt, sbintime_t pr, int flags)
244{
245 struct thread *td;
246 int rval;
247 WITNESS_SAVE_DECL(mtx);
248
249 td = curthread;
250 KASSERT(mtx != NULL, ("sleeping without a mutex"));
251 KASSERT(ident != NULL, ("msleep_spin_sbt: NULL ident"));
252 KASSERT(TD_IS_RUNNING(td), ("msleep_spin_sbt: curthread not running"));
253
254 if (SCHEDULER_STOPPED_TD(td))
255 return (0);
256
257 sleepq_lock(ident);
258 CTR5(KTR_PROC, "msleep_spin: thread %ld (pid %ld, %s) on %s (%p)",
259 td->td_tid, td->td_proc->p_pid, td->td_name, wmesg, ident);
260
261 DROP_GIANT();
262 mtx_assert(mtx, MA_OWNED | MA_NOTRECURSED);
263 WITNESS_SAVE(&mtx->lock_object, mtx);
264 mtx_unlock_spin(mtx);
265
266 /*
267 * We put ourselves on the sleep queue and start our timeout.
268 */
269 sleepq_add(ident, &mtx->lock_object, wmesg, SLEEPQ_SLEEP, 0);
270 if (sbt != 0)
271 sleepq_set_timeout_sbt(ident, sbt, pr, flags);
272
273 /*
274 * Can't call ktrace with any spin locks held so it can lock the
275 * ktrace_mtx lock, and WITNESS_WARN considers it an error to hold
276 * any spin lock. Thus, we have to drop the sleepq spin lock while
277 * we handle those requests. This is safe since we have placed our
278 * thread on the sleep queue already.
279 */
280#ifdef KTRACE
281 if (KTRPOINT(td, KTR_CSW)) {
282 sleepq_release(ident);
283 ktrcsw(1, 0, wmesg);
284 sleepq_lock(ident);
285 }
286#endif
287#ifdef WITNESS
288 sleepq_release(ident);
289 WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, NULL, "Sleeping on \"%s\"",
290 wmesg);
291 sleepq_lock(ident);
292#endif
293 if (sbt != 0)
294 rval = sleepq_timedwait(ident, 0);
295 else {
296 sleepq_wait(ident, 0);
297 rval = 0;
298 }
299#ifdef KTRACE
300 if (KTRPOINT(td, KTR_CSW))
301 ktrcsw(0, 0, wmesg);
302#endif
303 PICKUP_GIANT();
304 mtx_lock_spin(mtx);
305 WITNESS_RESTORE(&mtx->lock_object, mtx);
306 return (rval);
307}
308
309/*
310 * pause_sbt() delays the calling thread by the given signed binary
311 * time. During cold bootup, pause_sbt() uses the DELAY() function
312 * instead of the _sleep() function to do the waiting. The "sbt"
313 * argument must be greater than or equal to zero. A "sbt" value of
314 * zero is equivalent to a "sbt" value of one tick.
315 */
316int
317pause_sbt(const char *wmesg, sbintime_t sbt, sbintime_t pr, int flags)
318{
319 KASSERT(sbt >= 0, ("pause_sbt: timeout must be >= 0"));
320
321 /* silently convert invalid timeouts */
322 if (sbt == 0)
323 sbt = tick_sbt;
324
325 if ((cold && curthread == &thread0) || kdb_active ||
326 SCHEDULER_STOPPED()) {
327 /*
328 * We delay one second at a time to avoid overflowing the
329 * system specific DELAY() function(s):
330 */
331 while (sbt >= SBT_1S) {
332 DELAY(1000000);
333 sbt -= SBT_1S;
334 }
335 /* Do the delay remainder, if any */
336 sbt = howmany(sbt, SBT_1US);
337 if (sbt > 0)
338 DELAY(sbt);
339 return (EWOULDBLOCK);
340 }
341 return (_sleep(&pause_wchan[curcpu], NULL,
342 (flags & C_CATCH) ? PCATCH : 0, wmesg, sbt, pr, flags));
343}
344
345/*
346 * Make all threads sleeping on the specified identifier runnable.
347 */
348void
349wakeup(const void *ident)
350{
351 int wakeup_swapper;
352
353 sleepq_lock(ident);
354 wakeup_swapper = sleepq_broadcast(ident, SLEEPQ_SLEEP, 0, 0);
355 sleepq_release(ident);
356 if (wakeup_swapper) {
357 KASSERT(ident != &proc0,
358 ("wakeup and wakeup_swapper and proc0"));
359 kick_proc0();
360 }
361}
362
363/*
364 * Make a thread sleeping on the specified identifier runnable.
365 * May wake more than one thread if a target thread is currently
366 * swapped out.
367 */
368void
369wakeup_one(const void *ident)
370{
371 int wakeup_swapper;
372
373 sleepq_lock(ident);
374 wakeup_swapper = sleepq_signal(ident, SLEEPQ_SLEEP | SLEEPQ_DROP, 0, 0);
375 if (wakeup_swapper)
376 kick_proc0();
377}
378
379void
380wakeup_any(const void *ident)
381{
382 int wakeup_swapper;
383
384 sleepq_lock(ident);
385 wakeup_swapper = sleepq_signal(ident, SLEEPQ_SLEEP | SLEEPQ_UNFAIR |
386 SLEEPQ_DROP, 0, 0);
387 if (wakeup_swapper)
388 kick_proc0();
389}
390
391/*
392 * Signal sleeping waiters after the counter has reached zero.
393 */
394void
395_blockcount_wakeup(blockcount_t *bc, u_int old)
396{
397
398 KASSERT(_BLOCKCOUNT_WAITERS(old),
399 ("%s: no waiters on %p", __func__, bc));
400
401 if (atomic_cmpset_int(&bc->__count, _BLOCKCOUNT_WAITERS_FLAG, 0))
402 wakeup(bc);
403}
404
405/*
406 * Wait for a wakeup or a signal. This does not guarantee that the count is
407 * still zero on return. Callers wanting a precise answer should use
408 * blockcount_wait() with an interlock.
409 *
410 * If there is no work to wait for, return 0. If the sleep was interrupted by a
411 * signal, return EINTR or ERESTART, and return EAGAIN otherwise.
412 */
413int
414_blockcount_sleep(blockcount_t *bc, struct lock_object *lock, const char *wmesg,
415 int prio)
416{
417 void *wchan;
418 uintptr_t lock_state;
419 u_int old;
420 int ret;
421 bool catch, drop;
422
423 KASSERT(lock != &Giant.lock_object,
424 ("%s: cannot use Giant as the interlock", __func__));
425
426 catch = (prio & PCATCH) != 0;
427 drop = (prio & PDROP) != 0;
428 prio &= PRIMASK;
429
430 /*
431 * Synchronize with the fence in blockcount_release(). If we end up
432 * waiting, the sleepqueue lock acquisition will provide the required
433 * side effects.
434 *
435 * If there is no work to wait for, but waiters are present, try to put
436 * ourselves to sleep to avoid jumping ahead.
437 */
438 if (atomic_load_acq_int(&bc->__count) == 0) {
439 if (lock != NULL && drop)
440 LOCK_CLASS(lock)->lc_unlock(lock);
441 return (0);
442 }
443 lock_state = 0;
444 wchan = bc;
445 sleepq_lock(wchan);
446 DROP_GIANT();
447 if (lock != NULL)
448 lock_state = LOCK_CLASS(lock)->lc_unlock(lock);
449 old = blockcount_read(bc);
450 ret = 0;
451 do {
452 if (_BLOCKCOUNT_COUNT(old) == 0) {
453 sleepq_release(wchan);
454 goto out;
455 }
456 if (_BLOCKCOUNT_WAITERS(old))
457 break;
458 } while (!atomic_fcmpset_int(&bc->__count, &old,
459 old | _BLOCKCOUNT_WAITERS_FLAG));
460 sleepq_add(wchan, NULL, wmesg, catch ? SLEEPQ_INTERRUPTIBLE : 0, 0);
461 if (catch)
462 ret = sleepq_wait_sig(wchan, prio);
463 else
464 sleepq_wait(wchan, prio);
465 if (ret == 0)
466 ret = EAGAIN;
467
468out:
469 PICKUP_GIANT();
470 if (lock != NULL && !drop)
471 LOCK_CLASS(lock)->lc_lock(lock, lock_state);
472
473 return (ret);
474}
475
476static void
478{
479 thread_unlock(curthread);
481 kdb_reenter();
482 panic("%s: did not reenter debugger", __func__);
483}
484
485/*
486 * The machine independent parts of context switching.
487 *
488 * The thread lock is required on entry and is no longer held on return.
489 */
490void
492{
493 uint64_t runtime, new_switchtime;
494 struct thread *td;
495
496 td = curthread; /* XXX */
497 THREAD_LOCK_ASSERT(td, MA_OWNED | MA_NOTRECURSED);
498 KASSERT(!TD_ON_RUNQ(td), ("mi_switch: called by old code"));
499#ifdef INVARIANTS
500 if (!TD_ON_LOCK(td) && !TD_IS_RUNNING(td))
501 mtx_assert(&Giant, MA_NOTOWNED);
502#endif
503 KASSERT(td->td_critnest == 1 || KERNEL_PANICKED(),
504 ("mi_switch: switch in a critical section"));
505 KASSERT((flags & (SW_INVOL | SW_VOL)) != 0,
506 ("mi_switch: switch must be voluntary or involuntary"));
507
508 /*
509 * Don't perform context switches from the debugger.
510 */
511 if (kdb_active)
512 kdb_switch();
513 if (SCHEDULER_STOPPED_TD(td))
514 return;
515 if (flags & SW_VOL) {
516 td->td_ru.ru_nvcsw++;
517 td->td_swvoltick = ticks;
518 } else {
519 td->td_ru.ru_nivcsw++;
520 td->td_swinvoltick = ticks;
521 }
522#ifdef SCHED_STATS
523 SCHED_STAT_INC(sched_switch_stats[flags & SW_TYPE_MASK]);
524#endif
525 /*
526 * Compute the amount of time during which the current
527 * thread was running, and add that to its total so far.
528 */
529 new_switchtime = cpu_ticks();
530 runtime = new_switchtime - PCPU_GET(switchtime);
531 td->td_runtime += runtime;
532 td->td_incruntime += runtime;
533 PCPU_SET(switchtime, new_switchtime);
534 td->td_generation++; /* bump preempt-detect counter */
535 VM_CNT_INC(v_swtch);
536 PCPU_SET(switchticks, ticks);
537 CTR4(KTR_PROC, "mi_switch: old thread %ld (td_sched %p, pid %ld, %s)",
538 td->td_tid, td_get_sched(td), td->td_proc->p_pid, td->td_name);
539#ifdef KDTRACE_HOOKS
540 if (SDT_PROBES_ENABLED() &&
541 ((flags & SW_PREEMPT) != 0 || ((flags & SW_INVOL) != 0 &&
542 (flags & SW_TYPE_MASK) == SWT_NEEDRESCHED)))
543 SDT_PROBE0(sched, , , preempt);
544#endif
545 sched_switch(td, flags);
546 CTR4(KTR_PROC, "mi_switch: new thread %ld (td_sched %p, pid %ld, %s)",
547 td->td_tid, td_get_sched(td), td->td_proc->p_pid, td->td_name);
548
549 /*
550 * If the last thread was exiting, finish cleaning it up.
551 */
552 if ((td = PCPU_GET(deadthread))) {
553 PCPU_SET(deadthread, NULL);
554 thread_stash(td);
555 }
556 spinlock_exit();
557}
558
559/*
560 * Change thread state to be runnable, placing it on the run queue if
561 * it is in memory. If it is swapped out, return true so our caller
562 * will know to awaken the swapper.
563 *
564 * Requires the thread lock on entry, drops on exit.
565 */
566int
567setrunnable(struct thread *td, int srqflags)
568{
569 int swapin;
570
571 THREAD_LOCK_ASSERT(td, MA_OWNED);
572 KASSERT(td->td_proc->p_state != PRS_ZOMBIE,
573 ("setrunnable: pid %d is a zombie", td->td_proc->p_pid));
574
575 swapin = 0;
576 switch (TD_GET_STATE(td)) {
577 case TDS_RUNNING:
578 case TDS_RUNQ:
579 break;
580 case TDS_CAN_RUN:
581 KASSERT((td->td_flags & TDF_INMEM) != 0,
582 ("setrunnable: td %p not in mem, flags 0x%X inhibit 0x%X",
583 td, td->td_flags, td->td_inhibitors));
584 /* unlocks thread lock according to flags */
585 sched_wakeup(td, srqflags);
586 return (0);
587 case TDS_INHIBITED:
588 /*
589 * If we are only inhibited because we are swapped out
590 * arrange to swap in this process.
591 */
592 if (td->td_inhibitors == TDI_SWAPPED &&
593 (td->td_flags & TDF_SWAPINREQ) == 0) {
594 td->td_flags |= TDF_SWAPINREQ;
595 swapin = 1;
596 }
597 break;
598 default:
599 panic("setrunnable: state 0x%x", TD_GET_STATE(td));
600 }
601 if ((srqflags & (SRQ_HOLD | SRQ_HOLDTD)) == 0)
602 thread_unlock(td);
603
604 return (swapin);
605}
606
607/*
608 * Compute a tenex style load average of a quantity on
609 * 1, 5 and 15 minute intervals.
610 */
611static void
612loadav(void *arg)
613{
614 int i, nrun;
615 struct loadavg *avg;
616
617 nrun = sched_load();
618 avg = &averunnable;
619
620 for (i = 0; i < 3; i++)
621 avg->ldavg[i] = (cexp[i] * avg->ldavg[i] +
622 nrun * FSCALE * (FSCALE - cexp[i])) >> FSHIFT;
623
624 /*
625 * Schedule the next update to occur after 5 seconds, but add a
626 * random variation to avoid synchronisation with processes that
627 * run at regular intervals.
628 */
629 callout_reset_sbt(&loadav_callout,
630 SBT_1US * (4000000 + (int)(random() % 2000001)), SBT_1US,
631 loadav, NULL, C_DIRECT_EXEC | C_PREL(32));
632}
633
634/* ARGSUSED */
635static void
637{
639
640 /* Kick off timeout driven events by calling first time. */
641 loadav(NULL);
642}
643
644int
646{
647
648 return ((u_int)ticks - (u_int)curthread->td_swvoltick >= hogticks);
649}
650
651void
653{
654
655 if (should_yield())
656 kern_yield(PRI_USER);
657}
658
659void
660kern_yield(int prio)
661{
662 struct thread *td;
663
664 td = curthread;
665 DROP_GIANT();
666 thread_lock(td);
667 if (prio == PRI_USER)
668 prio = td->td_user_pri;
669 if (prio >= 0)
670 sched_prio(td, prio);
671 mi_switch(SW_VOL | SWT_RELINQUISH);
672 PICKUP_GIANT();
673}
674
675/*
676 * General purpose yield system call.
677 */
678int
679sys_yield(struct thread *td, struct yield_args *uap)
680{
681
682 thread_lock(td);
683 if (PRI_BASE(td->td_pri_class) == PRI_TIMESHARE)
684 sched_prio(td, PRI_MAX_TIMESHARE);
685 mi_switch(SW_VOL | SWT_RELINQUISH);
686 td->td_retval[0] = 0;
687 return (0);
688}
689
690int
691sys_sched_getcpu(struct thread *td, struct sched_getcpu_args *uap)
692{
693 td->td_retval[0] = td->td_oncpu;
694 return (0);
695}
int priority
Definition: cpufreq_if.m:46
struct proc proc0
Definition: init_main.c:109
volatile int ticks
Definition: kern_clock.c:380
struct mtx __exclusive_cache_line Giant
Definition: kern_mutex.c:181
static struct pollrec pr[POLL_LIST_LEN]
Definition: kern_poll.c:261
void panic(const char *fmt,...)
int sys_yield(struct thread *td, struct yield_args *uap)
Definition: kern_synch.c:679
void kern_yield(int prio)
Definition: kern_synch.c:660
static fixpt_t cexp[3]
Definition: kern_synch.c:90
void _blockcount_wakeup(blockcount_t *bc, u_int old)
Definition: kern_synch.c:395
static void kdb_switch(void)
Definition: kern_synch.c:477
void mi_switch(int flags)
Definition: kern_synch.c:491
static void loadav(void *arg)
Definition: kern_synch.c:612
int sys_sched_getcpu(struct thread *td, struct sched_getcpu_args *uap)
Definition: kern_synch.c:691
static const char pause_wchan[MAXCPU]
Definition: kern_synch.c:80
int pause_sbt(const char *wmesg, sbintime_t sbt, sbintime_t pr, int flags)
Definition: kern_synch.c:317
int should_yield(void)
Definition: kern_synch.c:645
void wakeup_any(const void *ident)
Definition: kern_synch.c:380
int _sleep(const void *ident, struct lock_object *lock, int priority, const char *wmesg, sbintime_t sbt, sbintime_t pr, int flags)
Definition: kern_synch.c:135
SYSCTL_INT(_kern, OID_AUTO, fscale, CTLFLAG_RD, SYSCTL_NULL_INT_PTR, FSCALE, "Fixed-point scale factor used for calculating load average values")
void maybe_yield(void)
Definition: kern_synch.c:652
int msleep_spin_sbt(const void *ident, struct mtx *mtx, const char *wmesg, sbintime_t sbt, sbintime_t pr, int flags)
Definition: kern_synch.c:242
static void synch_setup(void *dummy)
Definition: kern_synch.c:636
SYSINIT(synch_setup, SI_SUB_KICK_SCHEDULER, SI_ORDER_FIRST, synch_setup, NULL)
SDT_PROVIDER_DECLARE(sched)
SDT_PROBE_DEFINE(sched,,, preempt)
__FBSDID("$FreeBSD$")
int setrunnable(struct thread *td, int srqflags)
Definition: kern_synch.c:567
static struct callout loadav_callout
Definition: kern_synch.c:82
struct loadavg averunnable
Definition: kern_synch.c:84
void wakeup(const void *ident)
Definition: kern_synch.c:349
void wakeup_one(const void *ident)
Definition: kern_synch.c:369
int hogticks
Definition: kern_synch.c:79
int _blockcount_sleep(blockcount_t *bc, struct lock_object *lock, const char *wmesg, int prio)
Definition: kern_synch.c:414
static void sleepinit(void *unused)
Definition: kern_synch.c:106
cpu_tick_f * cpu_ticks
Definition: kern_tc.c:2174
void thread_stash(struct thread *td)
Definition: kern_thread.c:573
void callout_init(struct callout *c, int mpsafe)
void sched_prio(struct thread *td, u_char prio)
Definition: sched_4bsd.c:901
int sched_load(void)
Definition: sched_4bsd.c:1574
void sched_switch(struct thread *td, int flags)
Definition: sched_4bsd.c:986
void sched_wakeup(struct thread *td, int srqflags)
Definition: sched_4bsd.c:1118
u_char __read_frequently kdb_active
Definition: subr_kdb.c:56
void kdb_reenter(void)
Definition: subr_kdb.c:558
void kdb_backtrace(void)
Definition: subr_kdb.c:429
int hz
Definition: subr_param.c:85
sbintime_t tick_sbt
Definition: subr_param.c:88
void sleepq_release(const void *wchan)
void init_sleepqueues(void)
int sleepq_wait_sig(const void *wchan, int pri)
int sleepq_broadcast(const void *wchan, int flags, int pri, int queue)
int sleepq_timedwait_sig(const void *wchan, int pri)
int sleepq_signal(const void *wchan, int flags, int pri, int queue)
int sleepq_timedwait(const void *wchan, int pri)
void sleepq_add(const void *wchan, struct lock_object *lock, const char *wmesg, int flags, int queue)
void sleepq_set_timeout_sbt(const void *wchan, sbintime_t sbt, sbintime_t pr, int flags)
void sleepq_wait(const void *wchan, int pri)
void sleepq_lock(const void *wchan)
uint16_t flags
Definition: subr_stats.c:2
struct mtx mtx
Definition: uipc_ktls.c:0
static int dummy