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(void);
157 static void sleepq_dtor(void *mem, int size, void *arg);
159 static int sleepq_init(void *mem, int size, int flags);
160 static int sleepq_resume_thread(struct sleepqueue *sq, struct thread *td,
162 static void sleepq_switch(void *wchan, int pri);
163 static void sleepq_timeout(void *arg);
165 SDT_PROBE_DECLARE(sched, , , sleep);
166 SDT_PROBE_DECLARE(sched, , , wakeup);
169 * Early initialization of sleep queues that is called from the sleepinit()
173 init_sleepqueues(void)
175 #ifdef SLEEPQUEUE_PROFILING
176 struct sysctl_oid *chain_oid;
181 for (i = 0; i < SC_TABLESIZE; i++) {
182 LIST_INIT(&sleepq_chains[i].sc_queues);
183 mtx_init(&sleepq_chains[i].sc_lock, "sleepq chain", NULL,
184 MTX_SPIN | MTX_RECURSE);
185 #ifdef SLEEPQUEUE_PROFILING
186 snprintf(chain_name, sizeof(chain_name), "%d", i);
187 chain_oid = SYSCTL_ADD_NODE(NULL,
188 SYSCTL_STATIC_CHILDREN(_debug_sleepq_chains), OID_AUTO,
189 chain_name, CTLFLAG_RD, NULL, "sleepq chain stats");
190 SYSCTL_ADD_UINT(NULL, SYSCTL_CHILDREN(chain_oid), OID_AUTO,
191 "depth", CTLFLAG_RD, &sleepq_chains[i].sc_depth, 0, NULL);
192 SYSCTL_ADD_UINT(NULL, SYSCTL_CHILDREN(chain_oid), OID_AUTO,
193 "max_depth", CTLFLAG_RD, &sleepq_chains[i].sc_max_depth, 0,
197 sleepq_zone = uma_zcreate("SLEEPQUEUE", sizeof(struct sleepqueue),
199 NULL, sleepq_dtor, sleepq_init, NULL, UMA_ALIGN_CACHE, 0);
201 NULL, NULL, sleepq_init, NULL, UMA_ALIGN_CACHE, 0);
204 thread0.td_sleepqueue = sleepq_alloc();
208 * Get a sleep queue for a new thread.
214 return (uma_zalloc(sleepq_zone, M_WAITOK));
218 * Free a sleep queue when a thread is destroyed.
221 sleepq_free(struct sleepqueue *sq)
224 uma_zfree(sleepq_zone, sq);
228 * Lock the sleep queue chain associated with the specified wait channel.
231 sleepq_lock(void *wchan)
233 struct sleepqueue_chain *sc;
235 sc = SC_LOOKUP(wchan);
236 mtx_lock_spin(&sc->sc_lock);
240 * Look up the sleep queue associated with a given wait channel in the hash
241 * table locking the associated sleep queue chain. If no queue is found in
242 * the table, NULL is returned.
245 sleepq_lookup(void *wchan)
247 struct sleepqueue_chain *sc;
248 struct sleepqueue *sq;
250 KASSERT(wchan != NULL, ("%s: invalid NULL wait channel", __func__));
251 sc = SC_LOOKUP(wchan);
252 mtx_assert(&sc->sc_lock, MA_OWNED);
253 LIST_FOREACH(sq, &sc->sc_queues, sq_hash)
254 if (sq->sq_wchan == wchan)
260 * Unlock the sleep queue chain associated with a given wait channel.
263 sleepq_release(void *wchan)
265 struct sleepqueue_chain *sc;
267 sc = SC_LOOKUP(wchan);
268 mtx_unlock_spin(&sc->sc_lock);
272 * Places the current thread on the sleep queue for the specified wait
273 * channel. If INVARIANTS is enabled, then it associates the passed in
274 * lock with the sleepq to make sure it is held when that sleep queue is
278 sleepq_add(void *wchan, struct lock_object *lock, const char *wmesg, int flags,
281 struct sleepqueue_chain *sc;
282 struct sleepqueue *sq;
286 sc = SC_LOOKUP(wchan);
287 mtx_assert(&sc->sc_lock, MA_OWNED);
288 MPASS(td->td_sleepqueue != NULL);
289 MPASS(wchan != NULL);
290 MPASS((queue >= 0) && (queue < NR_SLEEPQS));
292 /* If this thread is not allowed to sleep, die a horrible death. */
293 KASSERT(td->td_no_sleeping == 0,
294 ("%s: td %p to sleep on wchan %p with sleeping prohibited",
295 __func__, td, wchan));
297 /* Look up the sleep queue associated with the wait channel 'wchan'. */
298 sq = sleepq_lookup(wchan);
301 * If the wait channel does not already have a sleep queue, use
302 * this thread's sleep queue. Otherwise, insert the current thread
303 * into the sleep queue already in use by this wait channel.
309 sq = td->td_sleepqueue;
310 for (i = 0; i < NR_SLEEPQS; i++) {
311 KASSERT(TAILQ_EMPTY(&sq->sq_blocked[i]),
312 ("thread's sleep queue %d is not empty", i));
313 KASSERT(sq->sq_blockedcnt[i] == 0,
314 ("thread's sleep queue %d count mismatches", i));
316 KASSERT(LIST_EMPTY(&sq->sq_free),
317 ("thread's sleep queue has a non-empty free list"));
318 KASSERT(sq->sq_wchan == NULL, ("stale sq_wchan pointer"));
321 #ifdef SLEEPQUEUE_PROFILING
323 if (sc->sc_depth > sc->sc_max_depth) {
324 sc->sc_max_depth = sc->sc_depth;
325 if (sc->sc_max_depth > sleepq_max_depth)
326 sleepq_max_depth = sc->sc_max_depth;
329 sq = td->td_sleepqueue;
330 LIST_INSERT_HEAD(&sc->sc_queues, sq, sq_hash);
331 sq->sq_wchan = wchan;
332 sq->sq_type = flags & SLEEPQ_TYPE;
334 MPASS(wchan == sq->sq_wchan);
335 MPASS(lock == sq->sq_lock);
336 MPASS((flags & SLEEPQ_TYPE) == sq->sq_type);
337 LIST_INSERT_HEAD(&sq->sq_free, td->td_sleepqueue, sq_hash);
340 TAILQ_INSERT_TAIL(&sq->sq_blocked[queue], td, td_slpq);
341 sq->sq_blockedcnt[queue]++;
342 td->td_sleepqueue = NULL;
343 td->td_sqqueue = queue;
344 td->td_wchan = wchan;
345 td->td_wmesg = wmesg;
346 if (flags & SLEEPQ_INTERRUPTIBLE) {
347 td->td_flags |= TDF_SINTR;
348 td->td_flags &= ~TDF_SLEEPABORT;
354 * Sets a timeout that will remove the current thread from the specified
355 * sleep queue after timo ticks if the thread has not already been awakened.
358 sleepq_set_timeout_sbt(void *wchan, sbintime_t sbt, sbintime_t pr,
361 struct sleepqueue_chain *sc;
365 sc = SC_LOOKUP(wchan);
366 mtx_assert(&sc->sc_lock, MA_OWNED);
367 MPASS(TD_ON_SLEEPQ(td));
368 MPASS(td->td_sleepqueue == NULL);
369 MPASS(wchan != NULL);
370 callout_reset_sbt_on(&td->td_slpcallout, sbt, pr,
371 sleepq_timeout, td, PCPU_GET(cpuid), flags | C_DIRECT_EXEC);
375 * Return the number of actual sleepers for the specified queue.
378 sleepq_sleepcnt(void *wchan, int queue)
380 struct sleepqueue *sq;
382 KASSERT(wchan != NULL, ("%s: invalid NULL wait channel", __func__));
383 MPASS((queue >= 0) && (queue < NR_SLEEPQS));
384 sq = sleepq_lookup(wchan);
387 return (sq->sq_blockedcnt[queue]);
391 * Marks the pending sleep of the current thread as interruptible and
392 * makes an initial check for pending signals before putting a thread
393 * to sleep. Enters and exits with the thread lock held. Thread lock
394 * may have transitioned from the sleepq lock to a run lock.
397 sleepq_catch_signals(void *wchan, int pri)
399 struct sleepqueue_chain *sc;
400 struct sleepqueue *sq;
408 sc = SC_LOOKUP(wchan);
409 mtx_assert(&sc->sc_lock, MA_OWNED);
410 MPASS(wchan != NULL);
411 if ((td->td_pflags & TDP_WAKEUP) != 0) {
412 td->td_pflags &= ~TDP_WAKEUP;
419 * See if there are any pending signals for this thread. If not
420 * we can switch immediately. Otherwise do the signal processing
424 if ((td->td_flags & (TDF_NEEDSIGCHK | TDF_NEEDSUSPCHK)) == 0) {
425 sleepq_switch(wchan, pri);
429 mtx_unlock_spin(&sc->sc_lock);
430 CTR3(KTR_PROC, "sleepq catching signals: thread %p (pid %ld, %s)",
431 (void *)td, (long)p->p_pid, td->td_name);
434 mtx_lock(&ps->ps_mtx);
437 mtx_unlock(&ps->ps_mtx);
438 ret = thread_suspend_check(1);
439 MPASS(ret == 0 || ret == EINTR || ret == ERESTART);
441 if (SIGISMEMBER(ps->ps_sigintr, sig))
445 mtx_unlock(&ps->ps_mtx);
448 * Lock the per-process spinlock prior to dropping the PROC_LOCK
449 * to avoid a signal delivery race. PROC_LOCK, PROC_SLOCK, and
450 * thread_lock() are currently held in tdsendsignal().
453 mtx_lock_spin(&sc->sc_lock);
458 sleepq_switch(wchan, pri);
463 * There were pending signals and this thread is still
464 * on the sleep queue, remove it from the sleep queue.
466 if (TD_ON_SLEEPQ(td)) {
467 sq = sleepq_lookup(wchan);
468 if (sleepq_resume_thread(sq, td, 0)) {
471 * This thread hasn't gone to sleep yet, so it
472 * should not be swapped out.
474 panic("not waking up swapper");
478 mtx_unlock_spin(&sc->sc_lock);
479 MPASS(td->td_lock != &sc->sc_lock);
484 * Switches to another thread if we are still asleep on a sleep queue.
485 * Returns with thread lock.
488 sleepq_switch(void *wchan, int pri)
490 struct sleepqueue_chain *sc;
491 struct sleepqueue *sq;
495 sc = SC_LOOKUP(wchan);
496 mtx_assert(&sc->sc_lock, MA_OWNED);
497 THREAD_LOCK_ASSERT(td, MA_OWNED);
500 * If we have a sleep queue, then we've already been woken up, so
503 if (td->td_sleepqueue != NULL) {
504 mtx_unlock_spin(&sc->sc_lock);
509 * If TDF_TIMEOUT is set, then our sleep has been timed out
510 * already but we are still on the sleep queue, so dequeue the
513 if (td->td_flags & TDF_TIMEOUT) {
514 MPASS(TD_ON_SLEEPQ(td));
515 sq = sleepq_lookup(wchan);
516 if (sleepq_resume_thread(sq, td, 0)) {
519 * This thread hasn't gone to sleep yet, so it
520 * should not be swapped out.
522 panic("not waking up swapper");
525 mtx_unlock_spin(&sc->sc_lock);
528 #ifdef SLEEPQUEUE_PROFILING
530 sleepq_profile(td->td_wmesg);
532 MPASS(td->td_sleepqueue == NULL);
533 sched_sleep(td, pri);
534 thread_lock_set(td, &sc->sc_lock);
535 SDT_PROBE0(sched, , , sleep);
537 mi_switch(SW_VOL | SWT_SLEEPQ, NULL);
538 KASSERT(TD_IS_RUNNING(td), ("running but not TDS_RUNNING"));
539 CTR3(KTR_PROC, "sleepq resume: thread %p (pid %ld, %s)",
540 (void *)td, (long)td->td_proc->p_pid, (void *)td->td_name);
544 * Check to see if we timed out.
547 sleepq_check_timeout(void)
552 THREAD_LOCK_ASSERT(td, MA_OWNED);
555 * If TDF_TIMEOUT is set, we timed out.
557 if (td->td_flags & TDF_TIMEOUT) {
558 td->td_flags &= ~TDF_TIMEOUT;
559 return (EWOULDBLOCK);
563 * If TDF_TIMOFAIL is set, the timeout ran after we had
564 * already been woken up.
566 if (td->td_flags & TDF_TIMOFAIL)
567 td->td_flags &= ~TDF_TIMOFAIL;
570 * If callout_stop() fails, then the timeout is running on
571 * another CPU, so synchronize with it to avoid having it
572 * accidentally wake up a subsequent sleep.
574 else if (callout_stop(&td->td_slpcallout) == 0) {
575 td->td_flags |= TDF_TIMEOUT;
577 mi_switch(SW_INVOL | SWT_SLEEPQTIMO, NULL);
583 * Check to see if we were awoken by a signal.
586 sleepq_check_signals(void)
591 THREAD_LOCK_ASSERT(td, MA_OWNED);
593 /* We are no longer in an interruptible sleep. */
594 if (td->td_flags & TDF_SINTR)
595 td->td_flags &= ~TDF_SINTR;
597 if (td->td_flags & TDF_SLEEPABORT) {
598 td->td_flags &= ~TDF_SLEEPABORT;
599 return (td->td_intrval);
606 * Block the current thread until it is awakened from its sleep queue.
609 sleepq_wait(void *wchan, int pri)
614 MPASS(!(td->td_flags & TDF_SINTR));
616 sleepq_switch(wchan, pri);
621 * Block the current thread until it is awakened from its sleep queue
622 * or it is interrupted by a signal.
625 sleepq_wait_sig(void *wchan, int pri)
630 rcatch = sleepq_catch_signals(wchan, pri);
631 rval = sleepq_check_signals();
632 thread_unlock(curthread);
639 * Block the current thread until it is awakened from its sleep queue
640 * or it times out while waiting.
643 sleepq_timedwait(void *wchan, int pri)
649 MPASS(!(td->td_flags & TDF_SINTR));
651 sleepq_switch(wchan, pri);
652 rval = sleepq_check_timeout();
659 * Block the current thread until it is awakened from its sleep queue,
660 * it is interrupted by a signal, or it times out waiting to be awakened.
663 sleepq_timedwait_sig(void *wchan, int pri)
665 int rcatch, rvalt, rvals;
667 rcatch = sleepq_catch_signals(wchan, pri);
668 rvalt = sleepq_check_timeout();
669 rvals = sleepq_check_signals();
670 thread_unlock(curthread);
679 * Returns the type of sleepqueue given a waitchannel.
682 sleepq_type(void *wchan)
684 struct sleepqueue *sq;
687 MPASS(wchan != NULL);
690 sq = sleepq_lookup(wchan);
692 sleepq_release(wchan);
696 sleepq_release(wchan);
701 * Removes a thread from a sleep queue and makes it
705 sleepq_resume_thread(struct sleepqueue *sq, struct thread *td, int pri)
707 struct sleepqueue_chain *sc;
710 MPASS(sq->sq_wchan != NULL);
711 MPASS(td->td_wchan == sq->sq_wchan);
712 MPASS(td->td_sqqueue < NR_SLEEPQS && td->td_sqqueue >= 0);
713 THREAD_LOCK_ASSERT(td, MA_OWNED);
714 sc = SC_LOOKUP(sq->sq_wchan);
715 mtx_assert(&sc->sc_lock, MA_OWNED);
717 SDT_PROBE2(sched, , , wakeup, td, td->td_proc);
719 /* Remove the thread from the queue. */
720 sq->sq_blockedcnt[td->td_sqqueue]--;
721 TAILQ_REMOVE(&sq->sq_blocked[td->td_sqqueue], td, td_slpq);
724 * Get a sleep queue for this thread. If this is the last waiter,
725 * use the queue itself and take it out of the chain, otherwise,
726 * remove a queue from the free list.
728 if (LIST_EMPTY(&sq->sq_free)) {
729 td->td_sleepqueue = sq;
733 #ifdef SLEEPQUEUE_PROFILING
737 td->td_sleepqueue = LIST_FIRST(&sq->sq_free);
738 LIST_REMOVE(td->td_sleepqueue, sq_hash);
742 td->td_flags &= ~TDF_SINTR;
744 CTR3(KTR_PROC, "sleepq_wakeup: thread %p (pid %ld, %s)",
745 (void *)td, (long)td->td_proc->p_pid, td->td_name);
747 /* Adjust priority if requested. */
748 MPASS(pri == 0 || (pri >= PRI_MIN && pri <= PRI_MAX));
749 if (pri != 0 && td->td_priority > pri &&
750 PRI_BASE(td->td_pri_class) == PRI_TIMESHARE)
754 * Note that thread td might not be sleeping if it is running
755 * sleepq_catch_signals() on another CPU or is blocked on its
756 * proc lock to check signals. There's no need to mark the
757 * thread runnable in that case.
759 if (TD_IS_SLEEPING(td)) {
761 return (setrunnable(td));
768 * UMA zone item deallocator.
771 sleepq_dtor(void *mem, int size, void *arg)
773 struct sleepqueue *sq;
777 for (i = 0; i < NR_SLEEPQS; i++) {
778 MPASS(TAILQ_EMPTY(&sq->sq_blocked[i]));
779 MPASS(sq->sq_blockedcnt[i] == 0);
785 * UMA zone item initializer.
788 sleepq_init(void *mem, int size, int flags)
790 struct sleepqueue *sq;
795 for (i = 0; i < NR_SLEEPQS; i++) {
796 TAILQ_INIT(&sq->sq_blocked[i]);
797 sq->sq_blockedcnt[i] = 0;
799 LIST_INIT(&sq->sq_free);
804 * Find the highest priority thread sleeping on a wait channel and resume it.
807 sleepq_signal(void *wchan, int flags, int pri, int queue)
809 struct sleepqueue *sq;
810 struct thread *td, *besttd;
813 CTR2(KTR_PROC, "sleepq_signal(%p, %d)", wchan, flags);
814 KASSERT(wchan != NULL, ("%s: invalid NULL wait channel", __func__));
815 MPASS((queue >= 0) && (queue < NR_SLEEPQS));
816 sq = sleepq_lookup(wchan);
819 KASSERT(sq->sq_type == (flags & SLEEPQ_TYPE),
820 ("%s: mismatch between sleep/wakeup and cv_*", __func__));
823 * Find the highest priority thread on the queue. If there is a
824 * tie, use the thread that first appears in the queue as it has
825 * been sleeping the longest since threads are always added to
826 * the tail of sleep queues.
829 TAILQ_FOREACH(td, &sq->sq_blocked[queue], td_slpq) {
830 if (besttd == NULL || td->td_priority < besttd->td_priority)
833 MPASS(besttd != NULL);
835 wakeup_swapper = sleepq_resume_thread(sq, besttd, pri);
836 thread_unlock(besttd);
837 return (wakeup_swapper);
841 * Resume all threads sleeping on a specified wait channel.
844 sleepq_broadcast(void *wchan, int flags, int pri, int queue)
846 struct sleepqueue *sq;
847 struct thread *td, *tdn;
850 CTR2(KTR_PROC, "sleepq_broadcast(%p, %d)", wchan, flags);
851 KASSERT(wchan != NULL, ("%s: invalid NULL wait channel", __func__));
852 MPASS((queue >= 0) && (queue < NR_SLEEPQS));
853 sq = sleepq_lookup(wchan);
856 KASSERT(sq->sq_type == (flags & SLEEPQ_TYPE),
857 ("%s: mismatch between sleep/wakeup and cv_*", __func__));
859 /* Resume all blocked threads on the sleep queue. */
861 TAILQ_FOREACH_SAFE(td, &sq->sq_blocked[queue], td_slpq, tdn) {
863 if (sleepq_resume_thread(sq, td, pri))
867 return (wakeup_swapper);
871 * Time sleeping threads out. When the timeout expires, the thread is
872 * removed from the sleep queue and made runnable if it is still asleep.
875 sleepq_timeout(void *arg)
877 struct sleepqueue_chain *sc;
878 struct sleepqueue *sq;
885 CTR3(KTR_PROC, "sleepq_timeout: thread %p (pid %ld, %s)",
886 (void *)td, (long)td->td_proc->p_pid, (void *)td->td_name);
889 * First, see if the thread is asleep and get the wait channel if
893 if (TD_IS_SLEEPING(td) && TD_ON_SLEEPQ(td)) {
894 wchan = td->td_wchan;
895 sc = SC_LOOKUP(wchan);
896 THREAD_LOCKPTR_ASSERT(td, &sc->sc_lock);
897 sq = sleepq_lookup(wchan);
899 td->td_flags |= TDF_TIMEOUT;
900 wakeup_swapper = sleepq_resume_thread(sq, td, 0);
908 * If the thread is on the SLEEPQ but isn't sleeping yet, it
909 * can either be on another CPU in between sleepq_add() and
910 * one of the sleepq_*wait*() routines or it can be in
911 * sleepq_catch_signals().
913 if (TD_ON_SLEEPQ(td)) {
914 td->td_flags |= TDF_TIMEOUT;
920 * Now check for the edge cases. First, if TDF_TIMEOUT is set,
921 * then the other thread has already yielded to us, so clear
922 * the flag and resume it. If TDF_TIMEOUT is not set, then the
923 * we know that the other thread is not on a sleep queue, but it
924 * hasn't resumed execution yet. In that case, set TDF_TIMOFAIL
925 * to let it know that the timeout has already run and doesn't
926 * need to be canceled.
928 if (td->td_flags & TDF_TIMEOUT) {
929 MPASS(TD_IS_SLEEPING(td));
930 td->td_flags &= ~TDF_TIMEOUT;
932 wakeup_swapper = setrunnable(td);
934 td->td_flags |= TDF_TIMOFAIL;
941 * Resumes a specific thread from the sleep queue associated with a specific
942 * wait channel if it is on that queue.
945 sleepq_remove(struct thread *td, void *wchan)
947 struct sleepqueue *sq;
951 * Look up the sleep queue for this wait channel, then re-check
952 * that the thread is asleep on that channel, if it is not, then
955 MPASS(wchan != NULL);
957 sq = sleepq_lookup(wchan);
959 * We can not lock the thread here as it may be sleeping on a
960 * different sleepq. However, holding the sleepq lock for this
961 * wchan can guarantee that we do not miss a wakeup for this
962 * channel. The asserts below will catch any false positives.
964 if (!TD_ON_SLEEPQ(td) || td->td_wchan != wchan) {
965 sleepq_release(wchan);
968 /* Thread is asleep on sleep queue sq, so wake it up. */
971 MPASS(td->td_wchan == wchan);
972 wakeup_swapper = sleepq_resume_thread(sq, td, 0);
974 sleepq_release(wchan);
980 * Abort a thread as if an interrupt had occurred. Only abort
981 * interruptible waits (unfortunately it isn't safe to abort others).
984 sleepq_abort(struct thread *td, int intrval)
986 struct sleepqueue *sq;
989 THREAD_LOCK_ASSERT(td, MA_OWNED);
990 MPASS(TD_ON_SLEEPQ(td));
991 MPASS(td->td_flags & TDF_SINTR);
992 MPASS(intrval == EINTR || intrval == ERESTART);
995 * If the TDF_TIMEOUT flag is set, just leave. A
996 * timeout is scheduled anyhow.
998 if (td->td_flags & TDF_TIMEOUT)
1001 CTR3(KTR_PROC, "sleepq_abort: thread %p (pid %ld, %s)",
1002 (void *)td, (long)td->td_proc->p_pid, (void *)td->td_name);
1003 td->td_intrval = intrval;
1004 td->td_flags |= TDF_SLEEPABORT;
1006 * If the thread has not slept yet it will find the signal in
1007 * sleepq_catch_signals() and call sleepq_resume_thread. Otherwise
1008 * we have to do it here.
1010 if (!TD_IS_SLEEPING(td))
1012 wchan = td->td_wchan;
1013 MPASS(wchan != NULL);
1014 sq = sleepq_lookup(wchan);
1017 /* Thread is asleep on sleep queue sq, so wake it up. */
1018 return (sleepq_resume_thread(sq, td, 0));
1021 #ifdef SLEEPQUEUE_PROFILING
1022 #define SLEEPQ_PROF_LOCATIONS 1024
1023 #define SLEEPQ_SBUFSIZE 512
1024 struct sleepq_prof {
1025 LIST_ENTRY(sleepq_prof) sp_link;
1026 const char *sp_wmesg;
1030 LIST_HEAD(sqphead, sleepq_prof);
1032 struct sqphead sleepq_prof_free;
1033 struct sqphead sleepq_hash[SC_TABLESIZE];
1034 static struct sleepq_prof sleepq_profent[SLEEPQ_PROF_LOCATIONS];
1035 static struct mtx sleepq_prof_lock;
1036 MTX_SYSINIT(sleepq_prof_lock, &sleepq_prof_lock, "sleepq_prof", MTX_SPIN);
1039 sleepq_profile(const char *wmesg)
1041 struct sleepq_prof *sp;
1043 mtx_lock_spin(&sleepq_prof_lock);
1044 if (prof_enabled == 0)
1046 LIST_FOREACH(sp, &sleepq_hash[SC_HASH(wmesg)], sp_link)
1047 if (sp->sp_wmesg == wmesg)
1049 sp = LIST_FIRST(&sleepq_prof_free);
1052 sp->sp_wmesg = wmesg;
1053 LIST_REMOVE(sp, sp_link);
1054 LIST_INSERT_HEAD(&sleepq_hash[SC_HASH(wmesg)], sp, sp_link);
1058 mtx_unlock_spin(&sleepq_prof_lock);
1063 sleepq_prof_reset(void)
1065 struct sleepq_prof *sp;
1069 mtx_lock_spin(&sleepq_prof_lock);
1070 enabled = prof_enabled;
1072 for (i = 0; i < SC_TABLESIZE; i++)
1073 LIST_INIT(&sleepq_hash[i]);
1074 LIST_INIT(&sleepq_prof_free);
1075 for (i = 0; i < SLEEPQ_PROF_LOCATIONS; i++) {
1076 sp = &sleepq_profent[i];
1077 sp->sp_wmesg = NULL;
1079 LIST_INSERT_HEAD(&sleepq_prof_free, sp, sp_link);
1081 prof_enabled = enabled;
1082 mtx_unlock_spin(&sleepq_prof_lock);
1086 enable_sleepq_prof(SYSCTL_HANDLER_ARGS)
1091 error = sysctl_handle_int(oidp, &v, v, req);
1094 if (req->newptr == NULL)
1096 if (v == prof_enabled)
1099 sleepq_prof_reset();
1100 mtx_lock_spin(&sleepq_prof_lock);
1102 mtx_unlock_spin(&sleepq_prof_lock);
1108 reset_sleepq_prof_stats(SYSCTL_HANDLER_ARGS)
1113 error = sysctl_handle_int(oidp, &v, 0, req);
1116 if (req->newptr == NULL)
1120 sleepq_prof_reset();
1126 dump_sleepq_prof_stats(SYSCTL_HANDLER_ARGS)
1128 struct sleepq_prof *sp;
1134 error = sysctl_wire_old_buffer(req, 0);
1137 sb = sbuf_new_for_sysctl(NULL, NULL, SLEEPQ_SBUFSIZE, req);
1138 sbuf_printf(sb, "\nwmesg\tcount\n");
1139 enabled = prof_enabled;
1140 mtx_lock_spin(&sleepq_prof_lock);
1142 mtx_unlock_spin(&sleepq_prof_lock);
1143 for (i = 0; i < SC_TABLESIZE; i++) {
1144 LIST_FOREACH(sp, &sleepq_hash[i], sp_link) {
1145 sbuf_printf(sb, "%s\t%ld\n",
1146 sp->sp_wmesg, sp->sp_count);
1149 mtx_lock_spin(&sleepq_prof_lock);
1150 prof_enabled = enabled;
1151 mtx_unlock_spin(&sleepq_prof_lock);
1153 error = sbuf_finish(sb);
1158 SYSCTL_PROC(_debug_sleepq, OID_AUTO, stats, CTLTYPE_STRING | CTLFLAG_RD,
1159 NULL, 0, dump_sleepq_prof_stats, "A", "Sleepqueue profiling statistics");
1160 SYSCTL_PROC(_debug_sleepq, OID_AUTO, reset, CTLTYPE_INT | CTLFLAG_RW,
1161 NULL, 0, reset_sleepq_prof_stats, "I",
1162 "Reset sleepqueue profiling statistics");
1163 SYSCTL_PROC(_debug_sleepq, OID_AUTO, enable, CTLTYPE_INT | CTLFLAG_RW,
1164 NULL, 0, enable_sleepq_prof, "I", "Enable sleepqueue profiling");
1168 DB_SHOW_COMMAND(sleepq, db_show_sleepqueue)
1170 struct sleepqueue_chain *sc;
1171 struct sleepqueue *sq;
1173 struct lock_object *lock;
1183 * First, see if there is an active sleep queue for the wait channel
1184 * indicated by the address.
1186 wchan = (void *)addr;
1187 sc = SC_LOOKUP(wchan);
1188 LIST_FOREACH(sq, &sc->sc_queues, sq_hash)
1189 if (sq->sq_wchan == wchan)
1193 * Second, see if there is an active sleep queue at the address
1196 for (i = 0; i < SC_TABLESIZE; i++)
1197 LIST_FOREACH(sq, &sleepq_chains[i].sc_queues, sq_hash) {
1198 if (sq == (struct sleepqueue *)addr)
1202 db_printf("Unable to locate a sleep queue via %p\n", (void *)addr);
1205 db_printf("Wait channel: %p\n", sq->sq_wchan);
1206 db_printf("Queue type: %d\n", sq->sq_type);
1210 db_printf("Associated Interlock: %p - (%s) %s\n", lock,
1211 LOCK_CLASS(lock)->lc_name, lock->lo_name);
1214 db_printf("Blocked threads:\n");
1215 for (i = 0; i < NR_SLEEPQS; i++) {
1216 db_printf("\nQueue[%d]:\n", i);
1217 if (TAILQ_EMPTY(&sq->sq_blocked[i]))
1218 db_printf("\tempty\n");
1220 TAILQ_FOREACH(td, &sq->sq_blocked[0],
1222 db_printf("\t%p (tid %d, pid %d, \"%s\")\n", td,
1223 td->td_tid, td->td_proc->p_pid,
1226 db_printf("(expected: %u)\n", sq->sq_blockedcnt[i]);
1230 /* Alias 'show sleepqueue' to 'show sleepq'. */
1231 DB_SHOW_ALIAS(sleepqueue, db_show_sleepqueue);