2 * Copyright (c) 2004 John Baldwin <jhb@FreeBSD.org>
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
28 * Implementation of sleep queues used to hold queue of threads blocked on
29 * a wait channel. Sleep queues different from turnstiles in that wait
30 * channels are not owned by anyone, so there is no priority propagation.
31 * Sleep queues can also provide a timeout and can also be interrupted by
32 * signals. That said, there are several similarities between the turnstile
33 * and sleep queue implementations. (Note: turnstiles were implemented
34 * first.) For example, both use a hash table of the same size where each
35 * bucket is referred to as a "chain" that contains both a spin lock and
36 * a linked list of queues. An individual queue is located by using a hash
37 * to pick a chain, locking the chain, and then walking the chain searching
38 * for the queue. This means that a wait channel object does not need to
39 * embed it's queue head just as locks do not embed their turnstile queue
40 * head. Threads also carry around a sleep queue that they lend to the
41 * wait channel when blocking. Just as in turnstiles, the queue includes
42 * a free list of the sleep queues of other threads blocked on the same
43 * wait channel in the case of multiple waiters.
45 * Some additional functionality provided by sleep queues include the
46 * ability to set a timeout. The timeout is managed using a per-thread
47 * callout that resumes a thread if it is asleep. A thread may also
48 * catch signals while it is asleep (aka an interruptible sleep). The
49 * signal code uses sleepq_abort() to interrupt a sleeping thread. Finally,
50 * sleep queues also provide some extra assertions. One is not allowed to
51 * mix the sleep/wakeup and cv APIs for a given wait channel. Also, one
52 * must consistently use the same lock to synchronize with a wait channel,
53 * though this check is currently only a warning for sleep/wakeup due to
54 * pre-existing abuse of that API. The same lock must also be held when
55 * awakening threads, though that is currently only enforced for condition
59 #include <sys/cdefs.h>
60 __FBSDID("$FreeBSD$");
62 #include "opt_sleepqueue_profiling.h"
64 #include "opt_sched.h"
66 #include <sys/param.h>
67 #include <sys/systm.h>
69 #include <sys/kernel.h>
71 #include <sys/mutex.h>
74 #include <sys/sched.h>
76 #include <sys/signalvar.h>
77 #include <sys/sleepqueue.h>
78 #include <sys/sysctl.h>
87 * Constants for the hash table of sleep queue chains.
88 * SC_TABLESIZE must be a power of two for SC_MASK to work properly.
90 #define SC_TABLESIZE 256 /* Must be power of 2. */
91 #define SC_MASK (SC_TABLESIZE - 1)
93 #define SC_HASH(wc) ((((uintptr_t)(wc) >> SC_SHIFT) ^ (uintptr_t)(wc)) & \
95 #define SC_LOOKUP(wc) &sleepq_chains[SC_HASH(wc)]
98 * There two different lists of sleep queues. Both lists are connected
99 * via the sq_hash entries. The first list is the sleep queue chain list
100 * that a sleep queue is on when it is attached to a wait channel. The
101 * second list is the free list hung off of a sleep queue that is attached
104 * Each sleep queue also contains the wait channel it is attached to, the
105 * list of threads blocked on that wait channel, flags specific to the
106 * wait channel, and the lock used to synchronize with a wait channel.
107 * The flags are used to catch mismatches between the various consumers
108 * of the sleep queue API (e.g. sleep/wakeup and condition variables).
109 * The lock pointer is only used when invariants are enabled for various
113 * c - sleep queue chain lock
116 TAILQ_HEAD(, thread) sq_blocked[NR_SLEEPQS]; /* (c) Blocked threads. */
117 u_int sq_blockedcnt[NR_SLEEPQS]; /* (c) N. of blocked threads. */
118 LIST_ENTRY(sleepqueue) sq_hash; /* (c) Chain and free list. */
119 LIST_HEAD(, sleepqueue) sq_free; /* (c) Free queues. */
120 void *sq_wchan; /* (c) Wait channel. */
121 int sq_type; /* (c) Queue type. */
123 struct lock_object *sq_lock; /* (c) Associated lock. */
127 struct sleepqueue_chain {
128 LIST_HEAD(, sleepqueue) sc_queues; /* List of sleep queues. */
129 struct mtx sc_lock; /* Spin lock for this chain. */
130 #ifdef SLEEPQUEUE_PROFILING
131 u_int sc_depth; /* Length of sc_queues. */
132 u_int sc_max_depth; /* Max length of sc_queues. */
136 #ifdef SLEEPQUEUE_PROFILING
137 u_int sleepq_max_depth;
138 static SYSCTL_NODE(_debug, OID_AUTO, sleepq, CTLFLAG_RD, 0, "sleepq profiling");
139 static SYSCTL_NODE(_debug_sleepq, OID_AUTO, chains, CTLFLAG_RD, 0,
140 "sleepq chain stats");
141 SYSCTL_UINT(_debug_sleepq, OID_AUTO, max_depth, CTLFLAG_RD, &sleepq_max_depth,
142 0, "maxmimum depth achieved of a single chain");
144 static void sleepq_profile(const char *wmesg);
145 static int prof_enabled;
147 static struct sleepqueue_chain sleepq_chains[SC_TABLESIZE];
148 static uma_zone_t sleepq_zone;
151 * Prototypes for non-exported routines.
153 static int sleepq_catch_signals(void *wchan, int pri);
154 static int sleepq_check_signals(void);
155 static int sleepq_check_timeout(struct thread *);
156 static void sleepq_stop_timeout(struct thread *);
158 static void sleepq_dtor(void *mem, int size, void *arg);
160 static int sleepq_init(void *mem, int size, int flags);
161 static int sleepq_resume_thread(struct sleepqueue *sq, struct thread *td,
163 static void sleepq_switch(void *wchan, int pri);
164 static void sleepq_timeout(void *arg);
166 SDT_PROBE_DECLARE(sched, , , sleep);
167 SDT_PROBE_DECLARE(sched, , , wakeup);
170 * Initialize SLEEPQUEUE_PROFILING specific sysctl nodes.
171 * Note that it must happen after sleepinit() has been fully executed, so
172 * it must happen after SI_SUB_KMEM SYSINIT() subsystem setup.
174 #ifdef SLEEPQUEUE_PROFILING
176 init_sleepqueue_profiling(void)
179 struct sysctl_oid *chain_oid;
182 for (i = 0; i < SC_TABLESIZE; i++) {
183 snprintf(chain_name, sizeof(chain_name), "%u", i);
184 chain_oid = SYSCTL_ADD_NODE(NULL,
185 SYSCTL_STATIC_CHILDREN(_debug_sleepq_chains), OID_AUTO,
186 chain_name, CTLFLAG_RD, NULL, "sleepq chain stats");
187 SYSCTL_ADD_UINT(NULL, SYSCTL_CHILDREN(chain_oid), OID_AUTO,
188 "depth", CTLFLAG_RD, &sleepq_chains[i].sc_depth, 0, NULL);
189 SYSCTL_ADD_UINT(NULL, SYSCTL_CHILDREN(chain_oid), OID_AUTO,
190 "max_depth", CTLFLAG_RD, &sleepq_chains[i].sc_max_depth, 0,
195 SYSINIT(sleepqueue_profiling, SI_SUB_LOCK, SI_ORDER_ANY,
196 init_sleepqueue_profiling, NULL);
200 * Early initialization of sleep queues that is called from the sleepinit()
204 init_sleepqueues(void)
208 for (i = 0; i < SC_TABLESIZE; i++) {
209 LIST_INIT(&sleepq_chains[i].sc_queues);
210 mtx_init(&sleepq_chains[i].sc_lock, "sleepq chain", NULL,
211 MTX_SPIN | MTX_RECURSE);
213 sleepq_zone = uma_zcreate("SLEEPQUEUE", sizeof(struct sleepqueue),
215 NULL, sleepq_dtor, sleepq_init, NULL, UMA_ALIGN_CACHE, 0);
217 NULL, NULL, sleepq_init, NULL, UMA_ALIGN_CACHE, 0);
220 thread0.td_sleepqueue = sleepq_alloc();
224 * Get a sleep queue for a new thread.
230 return (uma_zalloc(sleepq_zone, M_WAITOK));
234 * Free a sleep queue when a thread is destroyed.
237 sleepq_free(struct sleepqueue *sq)
240 uma_zfree(sleepq_zone, sq);
244 * Lock the sleep queue chain associated with the specified wait channel.
247 sleepq_lock(void *wchan)
249 struct sleepqueue_chain *sc;
251 sc = SC_LOOKUP(wchan);
252 mtx_lock_spin(&sc->sc_lock);
256 * Look up the sleep queue associated with a given wait channel in the hash
257 * table locking the associated sleep queue chain. If no queue is found in
258 * the table, NULL is returned.
261 sleepq_lookup(void *wchan)
263 struct sleepqueue_chain *sc;
264 struct sleepqueue *sq;
266 KASSERT(wchan != NULL, ("%s: invalid NULL wait channel", __func__));
267 sc = SC_LOOKUP(wchan);
268 mtx_assert(&sc->sc_lock, MA_OWNED);
269 LIST_FOREACH(sq, &sc->sc_queues, sq_hash)
270 if (sq->sq_wchan == wchan)
276 * Unlock the sleep queue chain associated with a given wait channel.
279 sleepq_release(void *wchan)
281 struct sleepqueue_chain *sc;
283 sc = SC_LOOKUP(wchan);
284 mtx_unlock_spin(&sc->sc_lock);
288 * Places the current thread on the sleep queue for the specified wait
289 * channel. If INVARIANTS is enabled, then it associates the passed in
290 * lock with the sleepq to make sure it is held when that sleep queue is
294 sleepq_add(void *wchan, struct lock_object *lock, const char *wmesg, int flags,
297 struct sleepqueue_chain *sc;
298 struct sleepqueue *sq;
302 sc = SC_LOOKUP(wchan);
303 mtx_assert(&sc->sc_lock, MA_OWNED);
304 MPASS(td->td_sleepqueue != NULL);
305 MPASS(wchan != NULL);
306 MPASS((queue >= 0) && (queue < NR_SLEEPQS));
308 /* If this thread is not allowed to sleep, die a horrible death. */
309 KASSERT(td->td_no_sleeping == 0,
310 ("%s: td %p to sleep on wchan %p with sleeping prohibited",
311 __func__, td, wchan));
313 /* Look up the sleep queue associated with the wait channel 'wchan'. */
314 sq = sleepq_lookup(wchan);
317 * If the wait channel does not already have a sleep queue, use
318 * this thread's sleep queue. Otherwise, insert the current thread
319 * into the sleep queue already in use by this wait channel.
325 sq = td->td_sleepqueue;
326 for (i = 0; i < NR_SLEEPQS; i++) {
327 KASSERT(TAILQ_EMPTY(&sq->sq_blocked[i]),
328 ("thread's sleep queue %d is not empty", i));
329 KASSERT(sq->sq_blockedcnt[i] == 0,
330 ("thread's sleep queue %d count mismatches", i));
332 KASSERT(LIST_EMPTY(&sq->sq_free),
333 ("thread's sleep queue has a non-empty free list"));
334 KASSERT(sq->sq_wchan == NULL, ("stale sq_wchan pointer"));
337 #ifdef SLEEPQUEUE_PROFILING
339 if (sc->sc_depth > sc->sc_max_depth) {
340 sc->sc_max_depth = sc->sc_depth;
341 if (sc->sc_max_depth > sleepq_max_depth)
342 sleepq_max_depth = sc->sc_max_depth;
345 sq = td->td_sleepqueue;
346 LIST_INSERT_HEAD(&sc->sc_queues, sq, sq_hash);
347 sq->sq_wchan = wchan;
348 sq->sq_type = flags & SLEEPQ_TYPE;
350 MPASS(wchan == sq->sq_wchan);
351 MPASS(lock == sq->sq_lock);
352 MPASS((flags & SLEEPQ_TYPE) == sq->sq_type);
353 LIST_INSERT_HEAD(&sq->sq_free, td->td_sleepqueue, sq_hash);
356 TAILQ_INSERT_TAIL(&sq->sq_blocked[queue], td, td_slpq);
357 sq->sq_blockedcnt[queue]++;
358 td->td_sleepqueue = NULL;
359 td->td_sqqueue = queue;
360 td->td_wchan = wchan;
361 td->td_wmesg = wmesg;
362 if (flags & SLEEPQ_INTERRUPTIBLE) {
363 td->td_flags |= TDF_SINTR;
364 td->td_flags &= ~TDF_SLEEPABORT;
370 * Sets a timeout that will remove the current thread from the specified
371 * sleep queue after timo ticks if the thread has not already been awakened.
374 sleepq_set_timeout_sbt(void *wchan, sbintime_t sbt, sbintime_t pr,
381 mtx_lock_spin(&td->td_slpmutex);
382 callout_reset_sbt_on(&td->td_slpcallout, sbt, pr,
383 sleepq_timeout, td, PCPU_GET(cpuid), flags | C_DIRECT_EXEC);
384 mtx_unlock_spin(&td->td_slpmutex);
388 * Return the number of actual sleepers for the specified queue.
391 sleepq_sleepcnt(void *wchan, int queue)
393 struct sleepqueue *sq;
395 KASSERT(wchan != NULL, ("%s: invalid NULL wait channel", __func__));
396 MPASS((queue >= 0) && (queue < NR_SLEEPQS));
397 sq = sleepq_lookup(wchan);
400 return (sq->sq_blockedcnt[queue]);
404 * Marks the pending sleep of the current thread as interruptible and
405 * makes an initial check for pending signals before putting a thread
406 * to sleep. Enters and exits with the thread lock held. Thread lock
407 * may have transitioned from the sleepq lock to a run lock.
410 sleepq_catch_signals(void *wchan, int pri)
412 struct sleepqueue_chain *sc;
413 struct sleepqueue *sq;
421 sc = SC_LOOKUP(wchan);
422 mtx_assert(&sc->sc_lock, MA_OWNED);
423 MPASS(wchan != NULL);
424 if ((td->td_pflags & TDP_WAKEUP) != 0) {
425 td->td_pflags &= ~TDP_WAKEUP;
432 * See if there are any pending signals for this thread. If not
433 * we can switch immediately. Otherwise do the signal processing
437 if ((td->td_flags & (TDF_NEEDSIGCHK | TDF_NEEDSUSPCHK)) == 0) {
438 sleepq_switch(wchan, pri);
442 mtx_unlock_spin(&sc->sc_lock);
443 CTR3(KTR_PROC, "sleepq catching signals: thread %p (pid %ld, %s)",
444 (void *)td, (long)p->p_pid, td->td_name);
447 mtx_lock(&ps->ps_mtx);
450 mtx_unlock(&ps->ps_mtx);
451 ret = thread_suspend_check(1);
452 MPASS(ret == 0 || ret == EINTR || ret == ERESTART);
454 if (SIGISMEMBER(ps->ps_sigintr, sig))
458 mtx_unlock(&ps->ps_mtx);
461 * Lock the per-process spinlock prior to dropping the PROC_LOCK
462 * to avoid a signal delivery race. PROC_LOCK, PROC_SLOCK, and
463 * thread_lock() are currently held in tdsendsignal().
466 mtx_lock_spin(&sc->sc_lock);
471 sleepq_switch(wchan, pri);
476 * There were pending signals and this thread is still
477 * on the sleep queue, remove it from the sleep queue.
479 if (TD_ON_SLEEPQ(td)) {
480 sq = sleepq_lookup(wchan);
481 if (sleepq_resume_thread(sq, td, 0)) {
484 * This thread hasn't gone to sleep yet, so it
485 * should not be swapped out.
487 panic("not waking up swapper");
491 mtx_unlock_spin(&sc->sc_lock);
492 MPASS(td->td_lock != &sc->sc_lock);
497 * Switches to another thread if we are still asleep on a sleep queue.
498 * Returns with thread lock.
501 sleepq_switch(void *wchan, int pri)
503 struct sleepqueue_chain *sc;
504 struct sleepqueue *sq;
508 sc = SC_LOOKUP(wchan);
509 mtx_assert(&sc->sc_lock, MA_OWNED);
510 THREAD_LOCK_ASSERT(td, MA_OWNED);
513 * If we have a sleep queue, then we've already been woken up, so
516 if (td->td_sleepqueue != NULL) {
517 mtx_unlock_spin(&sc->sc_lock);
522 * If TDF_TIMEOUT is set, then our sleep has been timed out
523 * already but we are still on the sleep queue, so dequeue the
526 if (td->td_flags & TDF_TIMEOUT) {
527 MPASS(TD_ON_SLEEPQ(td));
528 sq = sleepq_lookup(wchan);
529 if (sleepq_resume_thread(sq, td, 0)) {
532 * This thread hasn't gone to sleep yet, so it
533 * should not be swapped out.
535 panic("not waking up swapper");
538 mtx_unlock_spin(&sc->sc_lock);
541 #ifdef SLEEPQUEUE_PROFILING
543 sleepq_profile(td->td_wmesg);
545 MPASS(td->td_sleepqueue == NULL);
546 sched_sleep(td, pri);
547 thread_lock_set(td, &sc->sc_lock);
548 SDT_PROBE0(sched, , , sleep);
550 mi_switch(SW_VOL | SWT_SLEEPQ, NULL);
551 KASSERT(TD_IS_RUNNING(td), ("running but not TDS_RUNNING"));
552 CTR3(KTR_PROC, "sleepq resume: thread %p (pid %ld, %s)",
553 (void *)td, (long)td->td_proc->p_pid, (void *)td->td_name);
557 * Check to see if we timed out.
560 sleepq_check_timeout(struct thread *td)
562 THREAD_LOCK_ASSERT(td, MA_OWNED);
565 * If TDF_TIMEOUT is set, we timed out.
567 if (td->td_flags & TDF_TIMEOUT) {
568 td->td_flags &= ~TDF_TIMEOUT;
569 return (EWOULDBLOCK);
575 * Atomically stop the timeout by using a mutex.
578 sleepq_stop_timeout(struct thread *td)
580 mtx_lock_spin(&td->td_slpmutex);
581 callout_stop(&td->td_slpcallout);
582 mtx_unlock_spin(&td->td_slpmutex);
586 * Check to see if we were awoken by a signal.
589 sleepq_check_signals(void)
594 THREAD_LOCK_ASSERT(td, MA_OWNED);
596 /* We are no longer in an interruptible sleep. */
597 if (td->td_flags & TDF_SINTR)
598 td->td_flags &= ~TDF_SINTR;
600 if (td->td_flags & TDF_SLEEPABORT) {
601 td->td_flags &= ~TDF_SLEEPABORT;
602 return (td->td_intrval);
609 * Block the current thread until it is awakened from its sleep queue.
612 sleepq_wait(void *wchan, int pri)
617 MPASS(!(td->td_flags & TDF_SINTR));
619 sleepq_switch(wchan, pri);
624 * Block the current thread until it is awakened from its sleep queue
625 * or it is interrupted by a signal.
628 sleepq_wait_sig(void *wchan, int pri)
633 rcatch = sleepq_catch_signals(wchan, pri);
634 rval = sleepq_check_signals();
635 thread_unlock(curthread);
642 * Block the current thread until it is awakened from its sleep queue
643 * or it times out while waiting.
646 sleepq_timedwait(void *wchan, int pri)
652 MPASS(!(td->td_flags & TDF_SINTR));
654 sleepq_switch(wchan, pri);
655 rval = sleepq_check_timeout(td);
658 sleepq_stop_timeout(td);
664 * Block the current thread until it is awakened from its sleep queue,
665 * it is interrupted by a signal, or it times out waiting to be awakened.
668 sleepq_timedwait_sig(void *wchan, int pri)
671 int rcatch, rvalt, rvals;
675 rcatch = sleepq_catch_signals(wchan, pri);
676 rvalt = sleepq_check_timeout(td);
677 rvals = sleepq_check_signals();
680 sleepq_stop_timeout(td);
690 * Returns the type of sleepqueue given a waitchannel.
693 sleepq_type(void *wchan)
695 struct sleepqueue *sq;
698 MPASS(wchan != NULL);
701 sq = sleepq_lookup(wchan);
703 sleepq_release(wchan);
707 sleepq_release(wchan);
712 * Removes a thread from a sleep queue and makes it
716 sleepq_resume_thread(struct sleepqueue *sq, struct thread *td, int pri)
718 struct sleepqueue_chain *sc;
721 MPASS(sq->sq_wchan != NULL);
722 MPASS(td->td_wchan == sq->sq_wchan);
723 MPASS(td->td_sqqueue < NR_SLEEPQS && td->td_sqqueue >= 0);
724 THREAD_LOCK_ASSERT(td, MA_OWNED);
725 sc = SC_LOOKUP(sq->sq_wchan);
726 mtx_assert(&sc->sc_lock, MA_OWNED);
728 SDT_PROBE2(sched, , , wakeup, td, td->td_proc);
730 /* Remove the thread from the queue. */
731 sq->sq_blockedcnt[td->td_sqqueue]--;
732 TAILQ_REMOVE(&sq->sq_blocked[td->td_sqqueue], td, td_slpq);
735 * Get a sleep queue for this thread. If this is the last waiter,
736 * use the queue itself and take it out of the chain, otherwise,
737 * remove a queue from the free list.
739 if (LIST_EMPTY(&sq->sq_free)) {
740 td->td_sleepqueue = sq;
744 #ifdef SLEEPQUEUE_PROFILING
748 td->td_sleepqueue = LIST_FIRST(&sq->sq_free);
749 LIST_REMOVE(td->td_sleepqueue, sq_hash);
753 td->td_flags &= ~TDF_SINTR;
755 CTR3(KTR_PROC, "sleepq_wakeup: thread %p (pid %ld, %s)",
756 (void *)td, (long)td->td_proc->p_pid, td->td_name);
758 /* Adjust priority if requested. */
759 MPASS(pri == 0 || (pri >= PRI_MIN && pri <= PRI_MAX));
760 if (pri != 0 && td->td_priority > pri &&
761 PRI_BASE(td->td_pri_class) == PRI_TIMESHARE)
765 * Note that thread td might not be sleeping if it is running
766 * sleepq_catch_signals() on another CPU or is blocked on its
767 * proc lock to check signals. There's no need to mark the
768 * thread runnable in that case.
770 if (TD_IS_SLEEPING(td)) {
772 return (setrunnable(td));
779 * UMA zone item deallocator.
782 sleepq_dtor(void *mem, int size, void *arg)
784 struct sleepqueue *sq;
788 for (i = 0; i < NR_SLEEPQS; i++) {
789 MPASS(TAILQ_EMPTY(&sq->sq_blocked[i]));
790 MPASS(sq->sq_blockedcnt[i] == 0);
796 * UMA zone item initializer.
799 sleepq_init(void *mem, int size, int flags)
801 struct sleepqueue *sq;
806 for (i = 0; i < NR_SLEEPQS; i++) {
807 TAILQ_INIT(&sq->sq_blocked[i]);
808 sq->sq_blockedcnt[i] = 0;
810 LIST_INIT(&sq->sq_free);
815 * Find the highest priority thread sleeping on a wait channel and resume it.
818 sleepq_signal(void *wchan, int flags, int pri, int queue)
820 struct sleepqueue *sq;
821 struct thread *td, *besttd;
824 CTR2(KTR_PROC, "sleepq_signal(%p, %d)", wchan, flags);
825 KASSERT(wchan != NULL, ("%s: invalid NULL wait channel", __func__));
826 MPASS((queue >= 0) && (queue < NR_SLEEPQS));
827 sq = sleepq_lookup(wchan);
830 KASSERT(sq->sq_type == (flags & SLEEPQ_TYPE),
831 ("%s: mismatch between sleep/wakeup and cv_*", __func__));
834 * Find the highest priority thread on the queue. If there is a
835 * tie, use the thread that first appears in the queue as it has
836 * been sleeping the longest since threads are always added to
837 * the tail of sleep queues.
840 TAILQ_FOREACH(td, &sq->sq_blocked[queue], td_slpq) {
841 if (besttd == NULL || td->td_priority < besttd->td_priority)
844 MPASS(besttd != NULL);
846 wakeup_swapper = sleepq_resume_thread(sq, besttd, pri);
847 thread_unlock(besttd);
848 return (wakeup_swapper);
852 * Resume all threads sleeping on a specified wait channel.
855 sleepq_broadcast(void *wchan, int flags, int pri, int queue)
857 struct sleepqueue *sq;
858 struct thread *td, *tdn;
861 CTR2(KTR_PROC, "sleepq_broadcast(%p, %d)", wchan, flags);
862 KASSERT(wchan != NULL, ("%s: invalid NULL wait channel", __func__));
863 MPASS((queue >= 0) && (queue < NR_SLEEPQS));
864 sq = sleepq_lookup(wchan);
867 KASSERT(sq->sq_type == (flags & SLEEPQ_TYPE),
868 ("%s: mismatch between sleep/wakeup and cv_*", __func__));
870 /* Resume all blocked threads on the sleep queue. */
872 TAILQ_FOREACH_SAFE(td, &sq->sq_blocked[queue], td_slpq, tdn) {
874 if (sleepq_resume_thread(sq, td, pri))
878 return (wakeup_swapper);
882 * Time sleeping threads out. When the timeout expires, the thread is
883 * removed from the sleep queue and made runnable if it is still asleep.
886 sleepq_timeout(void *arg)
888 struct thread *td = arg;
889 int wakeup_swapper = 0;
891 CTR3(KTR_PROC, "sleepq_timeout: thread %p (pid %ld, %s)",
892 (void *)td, (long)td->td_proc->p_pid, (void *)td->td_name);
894 /* Handle the three cases which can happen */
897 if (TD_ON_SLEEPQ(td)) {
898 if (TD_IS_SLEEPING(td)) {
899 struct sleepqueue_chain *sc;
900 struct sleepqueue *sq;
904 * Case I - thread is asleep and needs to be
907 wchan = td->td_wchan;
908 sc = SC_LOOKUP(wchan);
909 THREAD_LOCKPTR_ASSERT(td, &sc->sc_lock);
910 sq = sleepq_lookup(wchan);
912 td->td_flags |= TDF_TIMEOUT;
913 wakeup_swapper = sleepq_resume_thread(sq, td, 0);
916 * Case II - cancel going to sleep by setting
917 * the timeout flag because the target thread
918 * is not asleep yet. It can be on another CPU
919 * in between sleepq_add() and one of the
920 * sleepq_*wait*() routines or it can be in
921 * sleepq_catch_signals().
923 td->td_flags |= TDF_TIMEOUT;
927 * Case III - thread is already woken up by a wakeup
928 * call and should not timeout. Nothing to do!
937 * Resumes a specific thread from the sleep queue associated with a specific
938 * wait channel if it is on that queue.
941 sleepq_remove(struct thread *td, void *wchan)
943 struct sleepqueue *sq;
947 * Look up the sleep queue for this wait channel, then re-check
948 * that the thread is asleep on that channel, if it is not, then
951 MPASS(wchan != NULL);
953 sq = sleepq_lookup(wchan);
955 * We can not lock the thread here as it may be sleeping on a
956 * different sleepq. However, holding the sleepq lock for this
957 * wchan can guarantee that we do not miss a wakeup for this
958 * channel. The asserts below will catch any false positives.
960 if (!TD_ON_SLEEPQ(td) || td->td_wchan != wchan) {
961 sleepq_release(wchan);
964 /* Thread is asleep on sleep queue sq, so wake it up. */
967 MPASS(td->td_wchan == wchan);
968 wakeup_swapper = sleepq_resume_thread(sq, td, 0);
970 sleepq_release(wchan);
976 * Abort a thread as if an interrupt had occurred. Only abort
977 * interruptible waits (unfortunately it isn't safe to abort others).
980 sleepq_abort(struct thread *td, int intrval)
982 struct sleepqueue *sq;
985 THREAD_LOCK_ASSERT(td, MA_OWNED);
986 MPASS(TD_ON_SLEEPQ(td));
987 MPASS(td->td_flags & TDF_SINTR);
988 MPASS(intrval == EINTR || intrval == ERESTART);
991 * If the TDF_TIMEOUT flag is set, just leave. A
992 * timeout is scheduled anyhow.
994 if (td->td_flags & TDF_TIMEOUT)
997 CTR3(KTR_PROC, "sleepq_abort: thread %p (pid %ld, %s)",
998 (void *)td, (long)td->td_proc->p_pid, (void *)td->td_name);
999 td->td_intrval = intrval;
1000 td->td_flags |= TDF_SLEEPABORT;
1002 * If the thread has not slept yet it will find the signal in
1003 * sleepq_catch_signals() and call sleepq_resume_thread. Otherwise
1004 * we have to do it here.
1006 if (!TD_IS_SLEEPING(td))
1008 wchan = td->td_wchan;
1009 MPASS(wchan != NULL);
1010 sq = sleepq_lookup(wchan);
1013 /* Thread is asleep on sleep queue sq, so wake it up. */
1014 return (sleepq_resume_thread(sq, td, 0));
1017 #ifdef SLEEPQUEUE_PROFILING
1018 #define SLEEPQ_PROF_LOCATIONS 1024
1019 #define SLEEPQ_SBUFSIZE 512
1020 struct sleepq_prof {
1021 LIST_ENTRY(sleepq_prof) sp_link;
1022 const char *sp_wmesg;
1026 LIST_HEAD(sqphead, sleepq_prof);
1028 struct sqphead sleepq_prof_free;
1029 struct sqphead sleepq_hash[SC_TABLESIZE];
1030 static struct sleepq_prof sleepq_profent[SLEEPQ_PROF_LOCATIONS];
1031 static struct mtx sleepq_prof_lock;
1032 MTX_SYSINIT(sleepq_prof_lock, &sleepq_prof_lock, "sleepq_prof", MTX_SPIN);
1035 sleepq_profile(const char *wmesg)
1037 struct sleepq_prof *sp;
1039 mtx_lock_spin(&sleepq_prof_lock);
1040 if (prof_enabled == 0)
1042 LIST_FOREACH(sp, &sleepq_hash[SC_HASH(wmesg)], sp_link)
1043 if (sp->sp_wmesg == wmesg)
1045 sp = LIST_FIRST(&sleepq_prof_free);
1048 sp->sp_wmesg = wmesg;
1049 LIST_REMOVE(sp, sp_link);
1050 LIST_INSERT_HEAD(&sleepq_hash[SC_HASH(wmesg)], sp, sp_link);
1054 mtx_unlock_spin(&sleepq_prof_lock);
1059 sleepq_prof_reset(void)
1061 struct sleepq_prof *sp;
1065 mtx_lock_spin(&sleepq_prof_lock);
1066 enabled = prof_enabled;
1068 for (i = 0; i < SC_TABLESIZE; i++)
1069 LIST_INIT(&sleepq_hash[i]);
1070 LIST_INIT(&sleepq_prof_free);
1071 for (i = 0; i < SLEEPQ_PROF_LOCATIONS; i++) {
1072 sp = &sleepq_profent[i];
1073 sp->sp_wmesg = NULL;
1075 LIST_INSERT_HEAD(&sleepq_prof_free, sp, sp_link);
1077 prof_enabled = enabled;
1078 mtx_unlock_spin(&sleepq_prof_lock);
1082 enable_sleepq_prof(SYSCTL_HANDLER_ARGS)
1087 error = sysctl_handle_int(oidp, &v, v, req);
1090 if (req->newptr == NULL)
1092 if (v == prof_enabled)
1095 sleepq_prof_reset();
1096 mtx_lock_spin(&sleepq_prof_lock);
1098 mtx_unlock_spin(&sleepq_prof_lock);
1104 reset_sleepq_prof_stats(SYSCTL_HANDLER_ARGS)
1109 error = sysctl_handle_int(oidp, &v, 0, req);
1112 if (req->newptr == NULL)
1116 sleepq_prof_reset();
1122 dump_sleepq_prof_stats(SYSCTL_HANDLER_ARGS)
1124 struct sleepq_prof *sp;
1130 error = sysctl_wire_old_buffer(req, 0);
1133 sb = sbuf_new_for_sysctl(NULL, NULL, SLEEPQ_SBUFSIZE, req);
1134 sbuf_printf(sb, "\nwmesg\tcount\n");
1135 enabled = prof_enabled;
1136 mtx_lock_spin(&sleepq_prof_lock);
1138 mtx_unlock_spin(&sleepq_prof_lock);
1139 for (i = 0; i < SC_TABLESIZE; i++) {
1140 LIST_FOREACH(sp, &sleepq_hash[i], sp_link) {
1141 sbuf_printf(sb, "%s\t%ld\n",
1142 sp->sp_wmesg, sp->sp_count);
1145 mtx_lock_spin(&sleepq_prof_lock);
1146 prof_enabled = enabled;
1147 mtx_unlock_spin(&sleepq_prof_lock);
1149 error = sbuf_finish(sb);
1154 SYSCTL_PROC(_debug_sleepq, OID_AUTO, stats, CTLTYPE_STRING | CTLFLAG_RD,
1155 NULL, 0, dump_sleepq_prof_stats, "A", "Sleepqueue profiling statistics");
1156 SYSCTL_PROC(_debug_sleepq, OID_AUTO, reset, CTLTYPE_INT | CTLFLAG_RW,
1157 NULL, 0, reset_sleepq_prof_stats, "I",
1158 "Reset sleepqueue profiling statistics");
1159 SYSCTL_PROC(_debug_sleepq, OID_AUTO, enable, CTLTYPE_INT | CTLFLAG_RW,
1160 NULL, 0, enable_sleepq_prof, "I", "Enable sleepqueue profiling");
1164 DB_SHOW_COMMAND(sleepq, db_show_sleepqueue)
1166 struct sleepqueue_chain *sc;
1167 struct sleepqueue *sq;
1169 struct lock_object *lock;
1179 * First, see if there is an active sleep queue for the wait channel
1180 * indicated by the address.
1182 wchan = (void *)addr;
1183 sc = SC_LOOKUP(wchan);
1184 LIST_FOREACH(sq, &sc->sc_queues, sq_hash)
1185 if (sq->sq_wchan == wchan)
1189 * Second, see if there is an active sleep queue at the address
1192 for (i = 0; i < SC_TABLESIZE; i++)
1193 LIST_FOREACH(sq, &sleepq_chains[i].sc_queues, sq_hash) {
1194 if (sq == (struct sleepqueue *)addr)
1198 db_printf("Unable to locate a sleep queue via %p\n", (void *)addr);
1201 db_printf("Wait channel: %p\n", sq->sq_wchan);
1202 db_printf("Queue type: %d\n", sq->sq_type);
1206 db_printf("Associated Interlock: %p - (%s) %s\n", lock,
1207 LOCK_CLASS(lock)->lc_name, lock->lo_name);
1210 db_printf("Blocked threads:\n");
1211 for (i = 0; i < NR_SLEEPQS; i++) {
1212 db_printf("\nQueue[%d]:\n", i);
1213 if (TAILQ_EMPTY(&sq->sq_blocked[i]))
1214 db_printf("\tempty\n");
1216 TAILQ_FOREACH(td, &sq->sq_blocked[0],
1218 db_printf("\t%p (tid %d, pid %d, \"%s\")\n", td,
1219 td->td_tid, td->td_proc->p_pid,
1222 db_printf("(expected: %u)\n", sq->sq_blockedcnt[i]);
1226 /* Alias 'show sleepqueue' to 'show sleepq'. */
1227 DB_SHOW_ALIAS(sleepqueue, db_show_sleepqueue);