2 * Copyright (c) 1982, 1986, 1991, 1993
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34 * From: @(#)kern_clock.c 8.5 (Berkeley) 1/21/94
37 #include <sys/cdefs.h>
38 __FBSDID("$FreeBSD$");
40 #include "opt_callout_profiling.h"
42 #include "opt_timer.h"
46 #include <sys/param.h>
47 #include <sys/systm.h>
49 #include <sys/callout.h>
51 #include <sys/interrupt.h>
52 #include <sys/kernel.h>
55 #include <sys/malloc.h>
56 #include <sys/mutex.h>
59 #include <sys/sleepqueue.h>
60 #include <sys/sysctl.h>
64 #include <machine/cpu.h>
67 #ifndef NO_EVENTTIMERS
68 DPCPU_DECLARE(sbintime_t, hardclocktime);
71 SDT_PROVIDER_DEFINE(callout_execute);
72 SDT_PROBE_DEFINE1(callout_execute, kernel, , callout__start,
74 SDT_PROBE_DEFINE1(callout_execute, kernel, , callout__end,
77 #ifdef CALLOUT_PROFILING
79 SYSCTL_INT(_debug, OID_AUTO, to_avg_depth, CTLFLAG_RD, &avg_depth, 0,
80 "Average number of items examined per softclock call. Units = 1/1000");
81 static int avg_gcalls;
82 SYSCTL_INT(_debug, OID_AUTO, to_avg_gcalls, CTLFLAG_RD, &avg_gcalls, 0,
83 "Average number of Giant callouts made per softclock call. Units = 1/1000");
84 static int avg_lockcalls;
85 SYSCTL_INT(_debug, OID_AUTO, to_avg_lockcalls, CTLFLAG_RD, &avg_lockcalls, 0,
86 "Average number of lock callouts made per softclock call. Units = 1/1000");
87 static int avg_mpcalls;
88 SYSCTL_INT(_debug, OID_AUTO, to_avg_mpcalls, CTLFLAG_RD, &avg_mpcalls, 0,
89 "Average number of MP callouts made per softclock call. Units = 1/1000");
90 static int avg_depth_dir;
91 SYSCTL_INT(_debug, OID_AUTO, to_avg_depth_dir, CTLFLAG_RD, &avg_depth_dir, 0,
92 "Average number of direct callouts examined per callout_process call. "
94 static int avg_lockcalls_dir;
95 SYSCTL_INT(_debug, OID_AUTO, to_avg_lockcalls_dir, CTLFLAG_RD,
96 &avg_lockcalls_dir, 0, "Average number of lock direct callouts made per "
97 "callout_process call. Units = 1/1000");
98 static int avg_mpcalls_dir;
99 SYSCTL_INT(_debug, OID_AUTO, to_avg_mpcalls_dir, CTLFLAG_RD, &avg_mpcalls_dir,
100 0, "Average number of MP direct callouts made per callout_process call. "
105 SYSCTL_INT(_kern, OID_AUTO, ncallout, CTLFLAG_RDTUN | CTLFLAG_NOFETCH, &ncallout, 0,
106 "Number of entries in callwheel and size of timeout() preallocation");
109 static int pin_default_swi = 1;
110 static int pin_pcpu_swi = 1;
112 static int pin_default_swi = 0;
113 static int pin_pcpu_swi = 0;
116 SYSCTL_INT(_kern, OID_AUTO, pin_default_swi, CTLFLAG_RDTUN | CTLFLAG_NOFETCH, &pin_default_swi,
117 0, "Pin the default (non-per-cpu) swi (shared with PCPU 0 swi)");
118 SYSCTL_INT(_kern, OID_AUTO, pin_pcpu_swi, CTLFLAG_RDTUN | CTLFLAG_NOFETCH, &pin_pcpu_swi,
119 0, "Pin the per-CPU swis (except PCPU 0, which is also default");
123 * allocate more timeout table slots when table overflows.
125 u_int callwheelsize, callwheelmask;
128 * The callout cpu exec entities represent informations necessary for
129 * describing the state of callouts currently running on the CPU and the ones
130 * necessary for migrating callouts to the new callout cpu. In particular,
131 * the first entry of the array cc_exec_entity holds informations for callout
132 * running in SWI thread context, while the second one holds informations
133 * for callout running directly from hardware interrupt context.
134 * The cached informations are very important for deferring migration when
135 * the migrating callout is already running.
138 struct callout *cc_next;
139 struct callout *cc_curr;
141 void (*ce_migration_func)(void *);
142 void *ce_migration_arg;
143 int ce_migration_cpu;
144 sbintime_t ce_migration_time;
145 sbintime_t ce_migration_prec;
152 * There is one struct callout_cpu per cpu, holding all relevant
153 * state for the callout processing thread on the individual CPU.
156 struct mtx_padalign cc_lock;
157 struct cc_exec cc_exec_entity[2];
158 struct callout *cc_callout;
159 struct callout_list *cc_callwheel;
160 struct callout_tailq cc_expireq;
161 struct callout_slist cc_callfree;
162 sbintime_t cc_firstevent;
163 sbintime_t cc_lastscan;
166 char cc_ktr_event_name[20];
169 #define cc_exec_curr cc_exec_entity[0].cc_curr
170 #define cc_exec_next cc_exec_entity[0].cc_next
171 #define cc_exec_cancel cc_exec_entity[0].cc_cancel
172 #define cc_exec_waiting cc_exec_entity[0].cc_waiting
173 #define cc_exec_curr_dir cc_exec_entity[1].cc_curr
174 #define cc_exec_next_dir cc_exec_entity[1].cc_next
175 #define cc_exec_cancel_dir cc_exec_entity[1].cc_cancel
176 #define cc_exec_waiting_dir cc_exec_entity[1].cc_waiting
179 #define cc_migration_func cc_exec_entity[0].ce_migration_func
180 #define cc_migration_arg cc_exec_entity[0].ce_migration_arg
181 #define cc_migration_cpu cc_exec_entity[0].ce_migration_cpu
182 #define cc_migration_time cc_exec_entity[0].ce_migration_time
183 #define cc_migration_prec cc_exec_entity[0].ce_migration_prec
184 #define cc_migration_func_dir cc_exec_entity[1].ce_migration_func
185 #define cc_migration_arg_dir cc_exec_entity[1].ce_migration_arg
186 #define cc_migration_cpu_dir cc_exec_entity[1].ce_migration_cpu
187 #define cc_migration_time_dir cc_exec_entity[1].ce_migration_time
188 #define cc_migration_prec_dir cc_exec_entity[1].ce_migration_prec
190 struct callout_cpu cc_cpu[MAXCPU];
191 #define CPUBLOCK MAXCPU
192 #define CC_CPU(cpu) (&cc_cpu[(cpu)])
193 #define CC_SELF() CC_CPU(PCPU_GET(cpuid))
195 struct callout_cpu cc_cpu;
196 #define CC_CPU(cpu) &cc_cpu
197 #define CC_SELF() &cc_cpu
199 #define CC_LOCK(cc) mtx_lock_spin(&(cc)->cc_lock)
200 #define CC_UNLOCK(cc) mtx_unlock_spin(&(cc)->cc_lock)
201 #define CC_LOCK_ASSERT(cc) mtx_assert(&(cc)->cc_lock, MA_OWNED)
203 static int timeout_cpu;
205 static void callout_cpu_init(struct callout_cpu *cc, int cpu);
206 static void softclock_call_cc(struct callout *c, struct callout_cpu *cc,
207 #ifdef CALLOUT_PROFILING
208 int *mpcalls, int *lockcalls, int *gcalls,
212 static MALLOC_DEFINE(M_CALLOUT, "callout", "Callout datastructures");
216 * cc_curr - If a callout is in progress, it is cc_curr.
217 * If cc_curr is non-NULL, threads waiting in
218 * callout_drain() will be woken up as soon as the
219 * relevant callout completes.
220 * cc_cancel - Changing to 1 with both callout_lock and cc_lock held
221 * guarantees that the current callout will not run.
222 * The softclock() function sets this to 0 before it
223 * drops callout_lock to acquire c_lock, and it calls
224 * the handler only if curr_cancelled is still 0 after
225 * cc_lock is successfully acquired.
226 * cc_waiting - If a thread is waiting in callout_drain(), then
227 * callout_wait is nonzero. Set only when
228 * cc_curr is non-NULL.
232 * Resets the execution entity tied to a specific callout cpu.
235 cc_cce_cleanup(struct callout_cpu *cc, int direct)
238 cc->cc_exec_entity[direct].cc_curr = NULL;
239 cc->cc_exec_entity[direct].cc_next = NULL;
240 cc->cc_exec_entity[direct].cc_cancel = false;
241 cc->cc_exec_entity[direct].cc_waiting = false;
243 cc->cc_exec_entity[direct].ce_migration_cpu = CPUBLOCK;
244 cc->cc_exec_entity[direct].ce_migration_time = 0;
245 cc->cc_exec_entity[direct].ce_migration_prec = 0;
246 cc->cc_exec_entity[direct].ce_migration_func = NULL;
247 cc->cc_exec_entity[direct].ce_migration_arg = NULL;
252 * Checks if migration is requested by a specific callout cpu.
255 cc_cce_migrating(struct callout_cpu *cc, int direct)
259 return (cc->cc_exec_entity[direct].ce_migration_cpu != CPUBLOCK);
266 * Kernel low level callwheel initialization
267 * called on cpu0 during kernel startup.
270 callout_callwheel_init(void *dummy)
272 struct callout_cpu *cc;
275 * Calculate the size of the callout wheel and the preallocated
276 * timeout() structures.
277 * XXX: Clip callout to result of previous function of maxusers
278 * maximum 384. This is still huge, but acceptable.
280 ncallout = imin(16 + maxproc + maxfiles, 18508);
281 TUNABLE_INT_FETCH("kern.ncallout", &ncallout);
284 * Calculate callout wheel size, should be next power of two higher
287 callwheelsize = 1 << fls(ncallout);
288 callwheelmask = callwheelsize - 1;
291 * Fetch whether we're pinning the swi's or not.
293 TUNABLE_INT_FETCH("kern.pin_default_swi", &pin_default_swi);
294 TUNABLE_INT_FETCH("kern.pin_pcpu_swi", &pin_pcpu_swi);
297 * Only cpu0 handles timeout(9) and receives a preallocation.
299 * XXX: Once all timeout(9) consumers are converted this can
302 timeout_cpu = PCPU_GET(cpuid);
303 cc = CC_CPU(timeout_cpu);
304 cc->cc_callout = malloc(ncallout * sizeof(struct callout),
305 M_CALLOUT, M_WAITOK);
306 callout_cpu_init(cc, timeout_cpu);
308 SYSINIT(callwheel_init, SI_SUB_CPU, SI_ORDER_ANY, callout_callwheel_init, NULL);
311 * Initialize the per-cpu callout structures.
314 callout_cpu_init(struct callout_cpu *cc, int cpu)
319 mtx_init(&cc->cc_lock, "callout", NULL, MTX_SPIN | MTX_RECURSE);
320 SLIST_INIT(&cc->cc_callfree);
321 cc->cc_callwheel = malloc(sizeof(struct callout_list) * callwheelsize,
322 M_CALLOUT, M_WAITOK);
323 for (i = 0; i < callwheelsize; i++)
324 LIST_INIT(&cc->cc_callwheel[i]);
325 TAILQ_INIT(&cc->cc_expireq);
326 cc->cc_firstevent = SBT_MAX;
327 for (i = 0; i < 2; i++)
328 cc_cce_cleanup(cc, i);
329 snprintf(cc->cc_ktr_event_name, sizeof(cc->cc_ktr_event_name),
330 "callwheel cpu %d", cpu);
331 if (cc->cc_callout == NULL) /* Only cpu0 handles timeout(9) */
333 for (i = 0; i < ncallout; i++) {
334 c = &cc->cc_callout[i];
336 c->c_flags = CALLOUT_LOCAL_ALLOC;
337 SLIST_INSERT_HEAD(&cc->cc_callfree, c, c_links.sle);
343 * Switches the cpu tied to a specific callout.
344 * The function expects a locked incoming callout cpu and returns with
345 * locked outcoming callout cpu.
347 static struct callout_cpu *
348 callout_cpu_switch(struct callout *c, struct callout_cpu *cc, int new_cpu)
350 struct callout_cpu *new_cc;
352 MPASS(c != NULL && cc != NULL);
356 * Avoid interrupts and preemption firing after the callout cpu
357 * is blocked in order to avoid deadlocks as the new thread
358 * may be willing to acquire the callout cpu lock.
363 new_cc = CC_CPU(new_cpu);
372 * Start standard softclock thread.
375 start_softclock(void *dummy)
377 struct callout_cpu *cc;
378 char name[MAXCOMLEN];
381 struct intr_event *ie;
384 cc = CC_CPU(timeout_cpu);
385 snprintf(name, sizeof(name), "clock (%d)", timeout_cpu);
386 if (swi_add(&clk_intr_event, name, softclock, cc, SWI_CLOCK,
387 INTR_MPSAFE, &cc->cc_cookie))
388 panic("died while creating standard software ithreads");
389 if (pin_default_swi &&
390 (intr_event_bind(clk_intr_event, timeout_cpu) != 0)) {
391 printf("%s: timeout clock couldn't be pinned to cpu %d\n",
398 if (cpu == timeout_cpu)
401 cc->cc_callout = NULL; /* Only cpu0 handles timeout(9). */
402 callout_cpu_init(cc, cpu);
403 snprintf(name, sizeof(name), "clock (%d)", cpu);
405 if (swi_add(&ie, name, softclock, cc, SWI_CLOCK,
406 INTR_MPSAFE, &cc->cc_cookie))
407 panic("died while creating standard software ithreads");
408 if (pin_pcpu_swi && (intr_event_bind(ie, cpu) != 0)) {
409 printf("%s: per-cpu clock couldn't be pinned to "
417 SYSINIT(start_softclock, SI_SUB_SOFTINTR, SI_ORDER_FIRST, start_softclock, NULL);
419 #define CC_HASH_SHIFT 8
422 callout_hash(sbintime_t sbt)
425 return (sbt >> (32 - CC_HASH_SHIFT));
429 callout_get_bucket(sbintime_t sbt)
432 return (callout_hash(sbt) & callwheelmask);
436 callout_process(sbintime_t now)
438 struct callout *tmp, *tmpn;
439 struct callout_cpu *cc;
440 struct callout_list *sc;
441 sbintime_t first, last, max, tmp_max;
443 u_int firstb, lastb, nowb;
444 #ifdef CALLOUT_PROFILING
445 int depth_dir = 0, mpcalls_dir = 0, lockcalls_dir = 0;
449 mtx_lock_spin_flags(&cc->cc_lock, MTX_QUIET);
451 /* Compute the buckets of the last scan and present times. */
452 firstb = callout_hash(cc->cc_lastscan);
453 cc->cc_lastscan = now;
454 nowb = callout_hash(now);
456 /* Compute the last bucket and minimum time of the bucket after it. */
458 lookahead = (SBT_1S / 16);
459 else if (nowb - firstb == 1)
460 lookahead = (SBT_1S / 8);
462 lookahead = (SBT_1S / 2);
464 first += (lookahead / 2);
466 last &= (0xffffffffffffffffLLU << (32 - CC_HASH_SHIFT));
467 lastb = callout_hash(last) - 1;
471 * Check if we wrapped around the entire wheel from the last scan.
472 * In case, we need to scan entirely the wheel for pending callouts.
474 if (lastb - firstb >= callwheelsize) {
475 lastb = firstb + callwheelsize - 1;
476 if (nowb - firstb >= callwheelsize)
480 /* Iterate callwheel from firstb to nowb and then up to lastb. */
482 sc = &cc->cc_callwheel[firstb & callwheelmask];
483 tmp = LIST_FIRST(sc);
484 while (tmp != NULL) {
485 /* Run the callout if present time within allowed. */
486 if (tmp->c_time <= now) {
488 * Consumer told us the callout may be run
489 * directly from hardware interrupt context.
491 if (tmp->c_flags & CALLOUT_DIRECT) {
492 #ifdef CALLOUT_PROFILING
495 cc->cc_exec_next_dir =
496 LIST_NEXT(tmp, c_links.le);
497 cc->cc_bucket = firstb & callwheelmask;
498 LIST_REMOVE(tmp, c_links.le);
499 softclock_call_cc(tmp, cc,
500 #ifdef CALLOUT_PROFILING
501 &mpcalls_dir, &lockcalls_dir, NULL,
504 tmp = cc->cc_exec_next_dir;
506 tmpn = LIST_NEXT(tmp, c_links.le);
507 LIST_REMOVE(tmp, c_links.le);
508 TAILQ_INSERT_TAIL(&cc->cc_expireq,
510 tmp->c_flags |= CALLOUT_PROCESSED;
515 /* Skip events from distant future. */
516 if (tmp->c_time >= max)
519 * Event minimal time is bigger than present maximal
520 * time, so it cannot be aggregated.
522 if (tmp->c_time > last) {
526 /* Update first and last time, respecting this event. */
527 if (tmp->c_time < first)
529 tmp_max = tmp->c_time + tmp->c_precision;
533 tmp = LIST_NEXT(tmp, c_links.le);
535 /* Proceed with the next bucket. */
538 * Stop if we looked after present time and found
539 * some event we can't execute at now.
540 * Stop if we looked far enough into the future.
542 } while (((int)(firstb - lastb)) <= 0);
543 cc->cc_firstevent = last;
544 #ifndef NO_EVENTTIMERS
545 cpu_new_callout(curcpu, last, first);
547 #ifdef CALLOUT_PROFILING
548 avg_depth_dir += (depth_dir * 1000 - avg_depth_dir) >> 8;
549 avg_mpcalls_dir += (mpcalls_dir * 1000 - avg_mpcalls_dir) >> 8;
550 avg_lockcalls_dir += (lockcalls_dir * 1000 - avg_lockcalls_dir) >> 8;
552 mtx_unlock_spin_flags(&cc->cc_lock, MTX_QUIET);
554 * swi_sched acquires the thread lock, so we don't want to call it
555 * with cc_lock held; incorrect locking order.
557 if (!TAILQ_EMPTY(&cc->cc_expireq))
558 swi_sched(cc->cc_cookie, 0);
561 static struct callout_cpu *
562 callout_lock(struct callout *c)
564 struct callout_cpu *cc;
570 if (cpu == CPUBLOCK) {
571 while (c->c_cpu == CPUBLOCK)
586 callout_cc_add(struct callout *c, struct callout_cpu *cc,
587 sbintime_t sbt, sbintime_t precision, void (*func)(void *),
588 void *arg, int cpu, int flags)
593 if (sbt < cc->cc_lastscan)
594 sbt = cc->cc_lastscan;
596 c->c_flags |= (CALLOUT_ACTIVE | CALLOUT_PENDING);
597 if (flags & C_DIRECT_EXEC)
598 c->c_flags |= CALLOUT_DIRECT;
599 c->c_flags &= ~CALLOUT_PROCESSED;
602 c->c_precision = precision;
603 bucket = callout_get_bucket(c->c_time);
604 CTR3(KTR_CALLOUT, "precision set for %p: %d.%08x",
605 c, (int)(c->c_precision >> 32),
606 (u_int)(c->c_precision & 0xffffffff));
607 LIST_INSERT_HEAD(&cc->cc_callwheel[bucket], c, c_links.le);
608 if (cc->cc_bucket == bucket)
609 cc->cc_exec_next_dir = c;
610 #ifndef NO_EVENTTIMERS
612 * Inform the eventtimers(4) subsystem there's a new callout
613 * that has been inserted, but only if really required.
615 if (SBT_MAX - c->c_time < c->c_precision)
616 c->c_precision = SBT_MAX - c->c_time;
617 sbt = c->c_time + c->c_precision;
618 if (sbt < cc->cc_firstevent) {
619 cc->cc_firstevent = sbt;
620 cpu_new_callout(cpu, sbt, c->c_time);
626 callout_cc_del(struct callout *c, struct callout_cpu *cc)
629 if ((c->c_flags & CALLOUT_LOCAL_ALLOC) == 0)
632 SLIST_INSERT_HEAD(&cc->cc_callfree, c, c_links.sle);
636 softclock_call_cc(struct callout *c, struct callout_cpu *cc,
637 #ifdef CALLOUT_PROFILING
638 int *mpcalls, int *lockcalls, int *gcalls,
642 struct rm_priotracker tracker;
643 void (*c_func)(void *);
645 struct lock_class *class;
646 struct lock_object *c_lock;
647 uintptr_t lock_status;
650 struct callout_cpu *new_cc;
651 void (*new_func)(void *);
654 sbintime_t new_prec, new_time;
656 #if defined(DIAGNOSTIC) || defined(CALLOUT_PROFILING)
657 sbintime_t sbt1, sbt2;
659 static sbintime_t maxdt = 2 * SBT_1MS; /* 2 msec */
660 static timeout_t *lastfunc;
663 KASSERT((c->c_flags & (CALLOUT_PENDING | CALLOUT_ACTIVE)) ==
664 (CALLOUT_PENDING | CALLOUT_ACTIVE),
665 ("softclock_call_cc: pend|act %p %x", c, c->c_flags));
666 class = (c->c_lock != NULL) ? LOCK_CLASS(c->c_lock) : NULL;
668 if (c->c_flags & CALLOUT_SHAREDLOCK) {
669 if (class == &lock_class_rm)
670 lock_status = (uintptr_t)&tracker;
677 c_flags = c->c_flags;
678 if (c->c_flags & CALLOUT_LOCAL_ALLOC)
679 c->c_flags = CALLOUT_LOCAL_ALLOC;
681 c->c_flags &= ~CALLOUT_PENDING;
682 cc->cc_exec_entity[direct].cc_curr = c;
683 cc->cc_exec_entity[direct].cc_cancel = false;
685 if (c_lock != NULL) {
686 class->lc_lock(c_lock, lock_status);
688 * The callout may have been cancelled
689 * while we switched locks.
691 if (cc->cc_exec_entity[direct].cc_cancel) {
692 class->lc_unlock(c_lock);
695 /* The callout cannot be stopped now. */
696 cc->cc_exec_entity[direct].cc_cancel = true;
697 if (c_lock == &Giant.lock_object) {
698 #ifdef CALLOUT_PROFILING
701 CTR3(KTR_CALLOUT, "callout giant %p func %p arg %p",
704 #ifdef CALLOUT_PROFILING
707 CTR3(KTR_CALLOUT, "callout lock %p func %p arg %p",
711 #ifdef CALLOUT_PROFILING
714 CTR3(KTR_CALLOUT, "callout %p func %p arg %p",
717 KTR_STATE3(KTR_SCHED, "callout", cc->cc_ktr_event_name, "running",
718 "func:%p", c_func, "arg:%p", c_arg, "direct:%d", direct);
719 #if defined(DIAGNOSTIC) || defined(CALLOUT_PROFILING)
722 THREAD_NO_SLEEPING();
723 SDT_PROBE(callout_execute, kernel, , callout__start, c, 0, 0, 0, 0);
725 SDT_PROBE(callout_execute, kernel, , callout__end, c, 0, 0, 0, 0);
726 THREAD_SLEEPING_OK();
727 #if defined(DIAGNOSTIC) || defined(CALLOUT_PROFILING)
731 if (lastfunc != c_func || sbt2 > maxdt * 2) {
734 "Expensive timeout(9) function: %p(%p) %jd.%09ld s\n",
735 c_func, c_arg, (intmax_t)ts2.tv_sec, ts2.tv_nsec);
741 KTR_STATE0(KTR_SCHED, "callout", cc->cc_ktr_event_name, "idle");
742 CTR1(KTR_CALLOUT, "callout %p finished", c);
743 if ((c_flags & CALLOUT_RETURNUNLOCKED) == 0)
744 class->lc_unlock(c_lock);
747 KASSERT(cc->cc_exec_entity[direct].cc_curr == c, ("mishandled cc_curr"));
748 cc->cc_exec_entity[direct].cc_curr = NULL;
749 if (cc->cc_exec_entity[direct].cc_waiting) {
751 * There is someone waiting for the
752 * callout to complete.
753 * If the callout was scheduled for
754 * migration just cancel it.
756 if (cc_cce_migrating(cc, direct)) {
757 cc_cce_cleanup(cc, direct);
760 * It should be assert here that the callout is not
761 * destroyed but that is not easy.
763 c->c_flags &= ~CALLOUT_DFRMIGRATION;
765 cc->cc_exec_entity[direct].cc_waiting = false;
767 wakeup(&cc->cc_exec_entity[direct].cc_waiting);
769 } else if (cc_cce_migrating(cc, direct)) {
770 KASSERT((c_flags & CALLOUT_LOCAL_ALLOC) == 0,
771 ("Migrating legacy callout %p", c));
774 * If the callout was scheduled for
775 * migration just perform it now.
777 new_cpu = cc->cc_exec_entity[direct].ce_migration_cpu;
778 new_time = cc->cc_exec_entity[direct].ce_migration_time;
779 new_prec = cc->cc_exec_entity[direct].ce_migration_prec;
780 new_func = cc->cc_exec_entity[direct].ce_migration_func;
781 new_arg = cc->cc_exec_entity[direct].ce_migration_arg;
782 cc_cce_cleanup(cc, direct);
785 * It should be assert here that the callout is not destroyed
786 * but that is not easy.
788 * As first thing, handle deferred callout stops.
790 if ((c->c_flags & CALLOUT_DFRMIGRATION) == 0) {
792 "deferred cancelled %p func %p arg %p",
793 c, new_func, new_arg);
794 callout_cc_del(c, cc);
797 c->c_flags &= ~CALLOUT_DFRMIGRATION;
799 new_cc = callout_cpu_switch(c, cc, new_cpu);
800 flags = (direct) ? C_DIRECT_EXEC : 0;
801 callout_cc_add(c, new_cc, new_time, new_prec, new_func,
802 new_arg, new_cpu, flags);
806 panic("migration should not happen");
810 * If the current callout is locally allocated (from
811 * timeout(9)) then put it on the freelist.
813 * Note: we need to check the cached copy of c_flags because
814 * if it was not local, then it's not safe to deref the
817 KASSERT((c_flags & CALLOUT_LOCAL_ALLOC) == 0 ||
818 c->c_flags == CALLOUT_LOCAL_ALLOC,
819 ("corrupted callout"));
820 if (c_flags & CALLOUT_LOCAL_ALLOC)
821 callout_cc_del(c, cc);
825 * The callout mechanism is based on the work of Adam M. Costello and
826 * George Varghese, published in a technical report entitled "Redesigning
827 * the BSD Callout and Timer Facilities" and modified slightly for inclusion
828 * in FreeBSD by Justin T. Gibbs. The original work on the data structures
829 * used in this implementation was published by G. Varghese and T. Lauck in
830 * the paper "Hashed and Hierarchical Timing Wheels: Data Structures for
831 * the Efficient Implementation of a Timer Facility" in the Proceedings of
832 * the 11th ACM Annual Symposium on Operating Systems Principles,
833 * Austin, Texas Nov 1987.
837 * Software (low priority) clock interrupt.
838 * Run periodic events from timeout queue.
843 struct callout_cpu *cc;
845 #ifdef CALLOUT_PROFILING
846 int depth = 0, gcalls = 0, lockcalls = 0, mpcalls = 0;
849 cc = (struct callout_cpu *)arg;
851 while ((c = TAILQ_FIRST(&cc->cc_expireq)) != NULL) {
852 TAILQ_REMOVE(&cc->cc_expireq, c, c_links.tqe);
853 softclock_call_cc(c, cc,
854 #ifdef CALLOUT_PROFILING
855 &mpcalls, &lockcalls, &gcalls,
858 #ifdef CALLOUT_PROFILING
862 #ifdef CALLOUT_PROFILING
863 avg_depth += (depth * 1000 - avg_depth) >> 8;
864 avg_mpcalls += (mpcalls * 1000 - avg_mpcalls) >> 8;
865 avg_lockcalls += (lockcalls * 1000 - avg_lockcalls) >> 8;
866 avg_gcalls += (gcalls * 1000 - avg_gcalls) >> 8;
873 * Execute a function after a specified length of time.
876 * Cancel previous timeout function call.
878 * callout_handle_init --
879 * Initialize a handle so that using it with untimeout is benign.
881 * See AT&T BCI Driver Reference Manual for specification. This
882 * implementation differs from that one in that although an
883 * identification value is returned from timeout, the original
884 * arguments to timeout as well as the identifier are used to
885 * identify entries for untimeout.
887 struct callout_handle
888 timeout(timeout_t *ftn, void *arg, int to_ticks)
890 struct callout_cpu *cc;
892 struct callout_handle handle;
894 cc = CC_CPU(timeout_cpu);
896 /* Fill in the next free callout structure. */
897 new = SLIST_FIRST(&cc->cc_callfree);
899 /* XXX Attempt to malloc first */
900 panic("timeout table full");
901 SLIST_REMOVE_HEAD(&cc->cc_callfree, c_links.sle);
902 callout_reset(new, to_ticks, ftn, arg);
903 handle.callout = new;
910 untimeout(timeout_t *ftn, void *arg, struct callout_handle handle)
912 struct callout_cpu *cc;
915 * Check for a handle that was initialized
916 * by callout_handle_init, but never used
917 * for a real timeout.
919 if (handle.callout == NULL)
922 cc = callout_lock(handle.callout);
923 if (handle.callout->c_func == ftn && handle.callout->c_arg == arg)
924 callout_stop(handle.callout);
929 callout_handle_init(struct callout_handle *handle)
931 handle->callout = NULL;
935 * New interface; clients allocate their own callout structures.
937 * callout_reset() - establish or change a timeout
938 * callout_stop() - disestablish a timeout
939 * callout_init() - initialize a callout structure so that it can
940 * safely be passed to callout_reset() and callout_stop()
942 * <sys/callout.h> defines three convenience macros:
944 * callout_active() - returns truth if callout has not been stopped,
945 * drained, or deactivated since the last time the callout was
947 * callout_pending() - returns truth if callout is still waiting for timeout
948 * callout_deactivate() - marks the callout as having been serviced
951 callout_reset_sbt_on(struct callout *c, sbintime_t sbt, sbintime_t precision,
952 void (*ftn)(void *), void *arg, int cpu, int flags)
954 sbintime_t to_sbt, pr;
955 struct callout_cpu *cc;
956 int cancelled, direct;
959 if (flags & C_ABSOLUTE) {
962 if ((flags & C_HARDCLOCK) && (sbt < tick_sbt))
964 if ((flags & C_HARDCLOCK) ||
965 #ifdef NO_EVENTTIMERS
966 sbt >= sbt_timethreshold) {
967 to_sbt = getsbinuptime();
969 /* Add safety belt for the case of hz > 1000. */
970 to_sbt += tc_tick_sbt - tick_sbt;
972 sbt >= sbt_tickthreshold) {
974 * Obtain the time of the last hardclock() call on
975 * this CPU directly from the kern_clocksource.c.
976 * This value is per-CPU, but it is equal for all
980 to_sbt = DPCPU_GET(hardclocktime);
983 to_sbt = DPCPU_GET(hardclocktime);
987 if ((flags & C_HARDCLOCK) == 0)
990 to_sbt = sbinuptime();
991 if (SBT_MAX - to_sbt < sbt)
995 pr = ((C_PRELGET(flags) < 0) ? sbt >> tc_precexp :
996 sbt >> C_PRELGET(flags));
1001 * Don't allow migration of pre-allocated callouts lest they
1002 * become unbalanced.
1004 if (c->c_flags & CALLOUT_LOCAL_ALLOC)
1006 direct = (c->c_flags & CALLOUT_DIRECT) != 0;
1007 KASSERT(!direct || c->c_lock == NULL,
1008 ("%s: direct callout %p has lock", __func__, c));
1009 cc = callout_lock(c);
1010 if (cc->cc_exec_entity[direct].cc_curr == c) {
1012 * We're being asked to reschedule a callout which is
1013 * currently in progress. If there is a lock then we
1014 * can cancel the callout if it has not really started.
1016 if (c->c_lock != NULL && !cc->cc_exec_entity[direct].cc_cancel)
1017 cancelled = cc->cc_exec_entity[direct].cc_cancel = true;
1018 if (cc->cc_exec_entity[direct].cc_waiting) {
1020 * Someone has called callout_drain to kill this
1021 * callout. Don't reschedule.
1023 CTR4(KTR_CALLOUT, "%s %p func %p arg %p",
1024 cancelled ? "cancelled" : "failed to cancel",
1025 c, c->c_func, c->c_arg);
1030 if (c->c_flags & CALLOUT_PENDING) {
1031 if ((c->c_flags & CALLOUT_PROCESSED) == 0) {
1032 if (cc->cc_exec_next_dir == c)
1033 cc->cc_exec_next_dir = LIST_NEXT(c, c_links.le);
1034 LIST_REMOVE(c, c_links.le);
1036 TAILQ_REMOVE(&cc->cc_expireq, c, c_links.tqe);
1038 c->c_flags &= ~(CALLOUT_ACTIVE | CALLOUT_PENDING);
1043 * If the callout must migrate try to perform it immediately.
1044 * If the callout is currently running, just defer the migration
1045 * to a more appropriate moment.
1047 if (c->c_cpu != cpu) {
1048 if (cc->cc_exec_entity[direct].cc_curr == c) {
1049 cc->cc_exec_entity[direct].ce_migration_cpu = cpu;
1050 cc->cc_exec_entity[direct].ce_migration_time
1052 cc->cc_exec_entity[direct].ce_migration_prec
1054 cc->cc_exec_entity[direct].ce_migration_func = ftn;
1055 cc->cc_exec_entity[direct].ce_migration_arg = arg;
1056 c->c_flags |= CALLOUT_DFRMIGRATION;
1058 "migration of %p func %p arg %p in %d.%08x to %u deferred",
1059 c, c->c_func, c->c_arg, (int)(to_sbt >> 32),
1060 (u_int)(to_sbt & 0xffffffff), cpu);
1064 cc = callout_cpu_switch(c, cc, cpu);
1068 callout_cc_add(c, cc, to_sbt, precision, ftn, arg, cpu, flags);
1069 CTR6(KTR_CALLOUT, "%sscheduled %p func %p arg %p in %d.%08x",
1070 cancelled ? "re" : "", c, c->c_func, c->c_arg, (int)(to_sbt >> 32),
1071 (u_int)(to_sbt & 0xffffffff));
1078 * Common idioms that can be optimized in the future.
1081 callout_schedule_on(struct callout *c, int to_ticks, int cpu)
1083 return callout_reset_on(c, to_ticks, c->c_func, c->c_arg, cpu);
1087 callout_schedule(struct callout *c, int to_ticks)
1089 return callout_reset_on(c, to_ticks, c->c_func, c->c_arg, c->c_cpu);
1093 _callout_stop_safe(struct callout *c, int safe)
1095 struct callout_cpu *cc, *old_cc;
1096 struct lock_class *class;
1097 int direct, sq_locked, use_lock;
1100 * Some old subsystems don't hold Giant while running a callout_stop(),
1101 * so just discard this check for the moment.
1103 if (!safe && c->c_lock != NULL) {
1104 if (c->c_lock == &Giant.lock_object)
1105 use_lock = mtx_owned(&Giant);
1108 class = LOCK_CLASS(c->c_lock);
1109 class->lc_assert(c->c_lock, LA_XLOCKED);
1113 direct = (c->c_flags & CALLOUT_DIRECT) != 0;
1117 cc = callout_lock(c);
1120 * If the callout was migrating while the callout cpu lock was
1121 * dropped, just drop the sleepqueue lock and check the states
1124 if (sq_locked != 0 && cc != old_cc) {
1127 sleepq_release(&old_cc->cc_exec_entity[direct].cc_waiting);
1132 panic("migration should not happen");
1137 * If the callout isn't pending, it's not on the queue, so
1138 * don't attempt to remove it from the queue. We can try to
1139 * stop it by other means however.
1141 if (!(c->c_flags & CALLOUT_PENDING)) {
1142 c->c_flags &= ~CALLOUT_ACTIVE;
1145 * If it wasn't on the queue and it isn't the current
1146 * callout, then we can't stop it, so just bail.
1148 if (cc->cc_exec_entity[direct].cc_curr != c) {
1149 CTR3(KTR_CALLOUT, "failed to stop %p func %p arg %p",
1150 c, c->c_func, c->c_arg);
1154 &cc->cc_exec_entity[direct].cc_waiting);
1160 * The current callout is running (or just
1161 * about to run) and blocking is allowed, so
1162 * just wait for the current invocation to
1165 while (cc->cc_exec_entity[direct].cc_curr == c) {
1167 * Use direct calls to sleepqueue interface
1168 * instead of cv/msleep in order to avoid
1169 * a LOR between cc_lock and sleepqueue
1170 * chain spinlocks. This piece of code
1171 * emulates a msleep_spin() call actually.
1173 * If we already have the sleepqueue chain
1174 * locked, then we can safely block. If we
1175 * don't already have it locked, however,
1176 * we have to drop the cc_lock to lock
1177 * it. This opens several races, so we
1178 * restart at the beginning once we have
1179 * both locks. If nothing has changed, then
1180 * we will end up back here with sq_locked
1186 &cc->cc_exec_entity[direct].cc_waiting);
1193 * Migration could be cancelled here, but
1194 * as long as it is still not sure when it
1195 * will be packed up, just let softclock()
1198 cc->cc_exec_entity[direct].cc_waiting = true;
1202 &cc->cc_exec_entity[direct].cc_waiting,
1203 &cc->cc_lock.lock_object, "codrain",
1206 &cc->cc_exec_entity[direct].cc_waiting,
1211 /* Reacquire locks previously released. */
1215 } else if (use_lock &&
1216 !cc->cc_exec_entity[direct].cc_cancel) {
1218 * The current callout is waiting for its
1219 * lock which we hold. Cancel the callout
1220 * and return. After our caller drops the
1221 * lock, the callout will be skipped in
1224 cc->cc_exec_entity[direct].cc_cancel = true;
1225 CTR3(KTR_CALLOUT, "cancelled %p func %p arg %p",
1226 c, c->c_func, c->c_arg);
1227 KASSERT(!cc_cce_migrating(cc, direct),
1228 ("callout wrongly scheduled for migration"));
1230 KASSERT(!sq_locked, ("sleepqueue chain locked"));
1232 } else if ((c->c_flags & CALLOUT_DFRMIGRATION) != 0) {
1233 c->c_flags &= ~CALLOUT_DFRMIGRATION;
1234 CTR3(KTR_CALLOUT, "postponing stop %p func %p arg %p",
1235 c, c->c_func, c->c_arg);
1239 CTR3(KTR_CALLOUT, "failed to stop %p func %p arg %p",
1240 c, c->c_func, c->c_arg);
1242 KASSERT(!sq_locked, ("sleepqueue chain still locked"));
1246 sleepq_release(&cc->cc_exec_entity[direct].cc_waiting);
1248 c->c_flags &= ~(CALLOUT_ACTIVE | CALLOUT_PENDING);
1250 CTR3(KTR_CALLOUT, "cancelled %p func %p arg %p",
1251 c, c->c_func, c->c_arg);
1252 if ((c->c_flags & CALLOUT_PROCESSED) == 0) {
1253 if (cc->cc_exec_next_dir == c)
1254 cc->cc_exec_next_dir = LIST_NEXT(c, c_links.le);
1255 LIST_REMOVE(c, c_links.le);
1257 TAILQ_REMOVE(&cc->cc_expireq, c, c_links.tqe);
1258 callout_cc_del(c, cc);
1265 callout_init(struct callout *c, int mpsafe)
1267 bzero(c, sizeof *c);
1270 c->c_flags = CALLOUT_RETURNUNLOCKED;
1272 c->c_lock = &Giant.lock_object;
1275 c->c_cpu = timeout_cpu;
1279 _callout_init_lock(struct callout *c, struct lock_object *lock, int flags)
1281 bzero(c, sizeof *c);
1283 KASSERT((flags & ~(CALLOUT_RETURNUNLOCKED | CALLOUT_SHAREDLOCK)) == 0,
1284 ("callout_init_lock: bad flags %d", flags));
1285 KASSERT(lock != NULL || (flags & CALLOUT_RETURNUNLOCKED) == 0,
1286 ("callout_init_lock: CALLOUT_RETURNUNLOCKED with no lock"));
1287 KASSERT(lock == NULL || !(LOCK_CLASS(lock)->lc_flags &
1288 (LC_SPINLOCK | LC_SLEEPABLE)), ("%s: invalid lock class",
1290 c->c_flags = flags & (CALLOUT_RETURNUNLOCKED | CALLOUT_SHAREDLOCK);
1291 c->c_cpu = timeout_cpu;
1294 #ifdef APM_FIXUP_CALLTODO
1296 * Adjust the kernel calltodo timeout list. This routine is used after
1297 * an APM resume to recalculate the calltodo timer list values with the
1298 * number of hz's we have been sleeping. The next hardclock() will detect
1299 * that there are fired timers and run softclock() to execute them.
1301 * Please note, I have not done an exhaustive analysis of what code this
1302 * might break. I am motivated to have my select()'s and alarm()'s that
1303 * have expired during suspend firing upon resume so that the applications
1304 * which set the timer can do the maintanence the timer was for as close
1305 * as possible to the originally intended time. Testing this code for a
1306 * week showed that resuming from a suspend resulted in 22 to 25 timers
1307 * firing, which seemed independant on whether the suspend was 2 hours or
1308 * 2 days. Your milage may vary. - Ken Key <key@cs.utk.edu>
1311 adjust_timeout_calltodo(struct timeval *time_change)
1313 register struct callout *p;
1314 unsigned long delta_ticks;
1317 * How many ticks were we asleep?
1318 * (stolen from tvtohz()).
1321 /* Don't do anything */
1322 if (time_change->tv_sec < 0)
1324 else if (time_change->tv_sec <= LONG_MAX / 1000000)
1325 delta_ticks = (time_change->tv_sec * 1000000 +
1326 time_change->tv_usec + (tick - 1)) / tick + 1;
1327 else if (time_change->tv_sec <= LONG_MAX / hz)
1328 delta_ticks = time_change->tv_sec * hz +
1329 (time_change->tv_usec + (tick - 1)) / tick + 1;
1331 delta_ticks = LONG_MAX;
1333 if (delta_ticks > INT_MAX)
1334 delta_ticks = INT_MAX;
1337 * Now rip through the timer calltodo list looking for timers
1341 /* don't collide with softclock() */
1343 for (p = calltodo.c_next; p != NULL; p = p->c_next) {
1344 p->c_time -= delta_ticks;
1346 /* Break if the timer had more time on it than delta_ticks */
1350 /* take back the ticks the timer didn't use (p->c_time <= 0) */
1351 delta_ticks = -p->c_time;
1357 #endif /* APM_FIXUP_CALLTODO */
1360 flssbt(sbintime_t sbt)
1363 sbt += (uint64_t)sbt >> 1;
1364 if (sizeof(long) >= sizeof(sbintime_t))
1367 return (flsl(((uint64_t)sbt) >> 32) + 32);
1372 * Dump immediate statistic snapshot of the scheduled callouts.
1375 sysctl_kern_callout_stat(SYSCTL_HANDLER_ARGS)
1377 struct callout *tmp;
1378 struct callout_cpu *cc;
1379 struct callout_list *sc;
1380 sbintime_t maxpr, maxt, medpr, medt, now, spr, st, t;
1381 int ct[64], cpr[64], ccpbk[32];
1382 int error, val, i, count, tcum, pcum, maxc, c, medc;
1388 error = sysctl_handle_int(oidp, &val, 0, req);
1389 if (error != 0 || req->newptr == NULL)
1392 st = spr = maxt = maxpr = 0;
1393 bzero(ccpbk, sizeof(ccpbk));
1394 bzero(ct, sizeof(ct));
1395 bzero(cpr, sizeof(cpr));
1401 cc = CC_CPU(timeout_cpu);
1404 for (i = 0; i < callwheelsize; i++) {
1405 sc = &cc->cc_callwheel[i];
1407 LIST_FOREACH(tmp, sc, c_links.le) {
1409 t = tmp->c_time - now;
1413 spr += tmp->c_precision / SBT_1US;
1416 if (tmp->c_precision > maxpr)
1417 maxpr = tmp->c_precision;
1419 cpr[flssbt(tmp->c_precision)]++;
1423 ccpbk[fls(c + c / 2)]++;
1431 for (i = 0, tcum = 0; i < 64 && tcum < count / 2; i++)
1433 medt = (i >= 2) ? (((sbintime_t)1) << (i - 2)) : 0;
1434 for (i = 0, pcum = 0; i < 64 && pcum < count / 2; i++)
1436 medpr = (i >= 2) ? (((sbintime_t)1) << (i - 2)) : 0;
1437 for (i = 0, c = 0; i < 32 && c < count / 2; i++)
1439 medc = (i >= 2) ? (1 << (i - 2)) : 0;
1441 printf("Scheduled callouts statistic snapshot:\n");
1442 printf(" Callouts: %6d Buckets: %6d*%-3d Bucket size: 0.%06ds\n",
1443 count, callwheelsize, mp_ncpus, 1000000 >> CC_HASH_SHIFT);
1444 printf(" C/Bk: med %5d avg %6d.%06jd max %6d\n",
1446 count / callwheelsize / mp_ncpus,
1447 (uint64_t)count * 1000000 / callwheelsize / mp_ncpus % 1000000,
1449 printf(" Time: med %5jd.%06jds avg %6jd.%06jds max %6jd.%06jds\n",
1450 medt / SBT_1S, (medt & 0xffffffff) * 1000000 >> 32,
1451 (st / count) / 1000000, (st / count) % 1000000,
1452 maxt / SBT_1S, (maxt & 0xffffffff) * 1000000 >> 32);
1453 printf(" Prec: med %5jd.%06jds avg %6jd.%06jds max %6jd.%06jds\n",
1454 medpr / SBT_1S, (medpr & 0xffffffff) * 1000000 >> 32,
1455 (spr / count) / 1000000, (spr / count) % 1000000,
1456 maxpr / SBT_1S, (maxpr & 0xffffffff) * 1000000 >> 32);
1457 printf(" Distribution: \tbuckets\t time\t tcum\t"
1459 for (i = 0, tcum = pcum = 0; i < 64; i++) {
1460 if (ct[i] == 0 && cpr[i] == 0)
1462 t = (i != 0) ? (((sbintime_t)1) << (i - 1)) : 0;
1465 printf(" %10jd.%06jds\t 2**%d\t%7d\t%7d\t%7d\t%7d\n",
1466 t / SBT_1S, (t & 0xffffffff) * 1000000 >> 32,
1467 i - 1 - (32 - CC_HASH_SHIFT),
1468 ct[i], tcum, cpr[i], pcum);
1472 SYSCTL_PROC(_kern, OID_AUTO, callout_stat,
1473 CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_MPSAFE,
1474 0, 0, sysctl_kern_callout_stat, "I",
1475 "Dump immediate statistic snapshot of the scheduled callouts");