2 * Copyright (c) 1982, 1986, 1991, 1993
3 * The Regents of the University of California. All rights reserved.
4 * (c) UNIX System Laboratories, Inc.
5 * All or some portions of this file are derived from material licensed
6 * to the University of California by American Telephone and Telegraph
7 * Co. or Unix System Laboratories, Inc. and are reproduced herein with
8 * the permission of UNIX System Laboratories, Inc.
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
13 * 1. Redistributions of source code must retain the above copyright
14 * notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 * notice, this list of conditions and the following disclaimer in the
17 * documentation and/or other materials provided with the distribution.
18 * 4. Neither the name of the University nor the names of its contributors
19 * may be used to endorse or promote products derived from this software
20 * without specific prior written permission.
22 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
25 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
34 * @(#)kern_clock.c 8.5 (Berkeley) 1/21/94
37 #include <sys/cdefs.h>
38 __FBSDID("$FreeBSD$");
41 #include "opt_device_polling.h"
42 #include "opt_hwpmc_hooks.h"
44 #include "opt_watchdog.h"
46 #include <sys/param.h>
47 #include <sys/systm.h>
48 #include <sys/callout.h>
50 #include <sys/kernel.h>
51 #include <sys/kthread.h>
54 #include <sys/mutex.h>
56 #include <sys/resource.h>
57 #include <sys/resourcevar.h>
58 #include <sys/sched.h>
60 #include <sys/signalvar.h>
61 #include <sys/sleepqueue.h>
65 #include <vm/vm_map.h>
66 #include <sys/sysctl.h>
68 #include <sys/interrupt.h>
69 #include <sys/limits.h>
70 #include <sys/timetc.h>
77 #include <sys/pmckern.h>
78 PMC_SOFT_DEFINE( , , clock, hard);
79 PMC_SOFT_DEFINE( , , clock, stat);
80 PMC_SOFT_DEFINE_EX( , , clock, prof, \
81 cpu_startprofclock, cpu_stopprofclock);
85 extern void hardclock_device_poll(void);
86 #endif /* DEVICE_POLLING */
88 static void initclocks(void *dummy);
89 SYSINIT(clocks, SI_SUB_CLOCKS, SI_ORDER_FIRST, initclocks, NULL);
91 /* Spin-lock protecting profiling statistics. */
92 static struct mtx time_lock;
94 SDT_PROVIDER_DECLARE(sched);
95 SDT_PROBE_DEFINE2(sched, , , tick, "struct thread *", "struct proc *");
98 sysctl_kern_cp_time(SYSCTL_HANDLER_ARGS)
101 long cp_time[CPUSTATES];
104 unsigned int cp_time32[CPUSTATES];
107 read_cpu_time(cp_time);
109 if (req->flags & SCTL_MASK32) {
111 return SYSCTL_OUT(req, 0, sizeof(cp_time32));
112 for (i = 0; i < CPUSTATES; i++)
113 cp_time32[i] = (unsigned int)cp_time[i];
114 error = SYSCTL_OUT(req, cp_time32, sizeof(cp_time32));
119 return SYSCTL_OUT(req, 0, sizeof(cp_time));
120 error = SYSCTL_OUT(req, cp_time, sizeof(cp_time));
125 SYSCTL_PROC(_kern, OID_AUTO, cp_time, CTLTYPE_LONG|CTLFLAG_RD|CTLFLAG_MPSAFE,
126 0,0, sysctl_kern_cp_time, "LU", "CPU time statistics");
128 static long empty[CPUSTATES];
131 sysctl_kern_cp_times(SYSCTL_HANDLER_ARGS)
138 unsigned int cp_time32[CPUSTATES];
144 if (req->flags & SCTL_MASK32)
145 return SYSCTL_OUT(req, 0, sizeof(cp_time32) * (mp_maxid + 1));
148 return SYSCTL_OUT(req, 0, sizeof(long) * CPUSTATES * (mp_maxid + 1));
150 for (error = 0, c = 0; error == 0 && c <= mp_maxid; c++) {
151 if (!CPU_ABSENT(c)) {
153 cp_time = pcpu->pc_cp_time;
158 if (req->flags & SCTL_MASK32) {
159 for (i = 0; i < CPUSTATES; i++)
160 cp_time32[i] = (unsigned int)cp_time[i];
161 error = SYSCTL_OUT(req, cp_time32, sizeof(cp_time32));
164 error = SYSCTL_OUT(req, cp_time, sizeof(long) * CPUSTATES);
169 SYSCTL_PROC(_kern, OID_AUTO, cp_times, CTLTYPE_LONG|CTLFLAG_RD|CTLFLAG_MPSAFE,
170 0,0, sysctl_kern_cp_times, "LU", "per-CPU time statistics");
173 static const char *blessed[] = {
179 static int slptime_threshold = 1800;
180 static int blktime_threshold = 900;
181 static int sleepfreq = 3;
189 int blkticks, i, slpticks, slptype, tryl, tticks;
193 blkticks = blktime_threshold * hz;
194 slpticks = slptime_threshold * hz;
197 * Avoid to sleep on the sx_lock in order to avoid a possible
198 * priority inversion problem leading to starvation.
199 * If the lock can't be held after 100 tries, panic.
201 if (!sx_try_slock(&allproc_lock)) {
203 panic("%s: possible deadlock detected on allproc_lock\n",
206 pause("allproc", sleepfreq * hz);
210 FOREACH_PROC_IN_SYSTEM(p) {
212 if (p->p_state == PRS_NEW) {
216 FOREACH_THREAD_IN_PROC(p, td) {
219 if (TD_ON_LOCK(td)) {
222 * The thread should be blocked on a
223 * turnstile, simply check if the
224 * turnstile channel is in good state.
226 MPASS(td->td_blocked != NULL);
228 tticks = ticks - td->td_blktick;
230 if (tticks > blkticks) {
233 * Accordingly with provided
234 * thresholds, this thread is
235 * stuck for too long on a
239 sx_sunlock(&allproc_lock);
240 panic("%s: possible deadlock detected for %p, blocked for %d ticks\n",
241 __func__, td, tticks);
243 } else if (TD_IS_SLEEPING(td) &&
247 * Check if the thread is sleeping on a
248 * lock, otherwise skip the check.
249 * Drop the thread lock in order to
250 * avoid a LOR with the sleepqueue
253 wchan = td->td_wchan;
254 tticks = ticks - td->td_slptick;
256 slptype = sleepq_type(wchan);
257 if ((slptype == SLEEPQ_SX ||
258 slptype == SLEEPQ_LK) &&
262 * Accordingly with provided
263 * thresholds, this thread is
264 * stuck for too long on a
266 * However, being on a
267 * sleepqueue, we might still
268 * check for the blessed
272 for (i = 0; blessed[i] != NULL;
274 if (!strcmp(blessed[i],
285 sx_sunlock(&allproc_lock);
286 panic("%s: possible deadlock detected for %p, blocked for %d ticks\n",
287 __func__, td, tticks);
294 sx_sunlock(&allproc_lock);
296 /* Sleep for sleepfreq seconds. */
297 pause("-", sleepfreq * hz);
301 static struct kthread_desc deadlkres_kd = {
304 (struct thread **)NULL
307 SYSINIT(deadlkres, SI_SUB_CLOCKS, SI_ORDER_ANY, kthread_start, &deadlkres_kd);
309 static SYSCTL_NODE(_debug, OID_AUTO, deadlkres, CTLFLAG_RW, 0,
310 "Deadlock resolver");
311 SYSCTL_INT(_debug_deadlkres, OID_AUTO, slptime_threshold, CTLFLAG_RW,
312 &slptime_threshold, 0,
313 "Number of seconds within is valid to sleep on a sleepqueue");
314 SYSCTL_INT(_debug_deadlkres, OID_AUTO, blktime_threshold, CTLFLAG_RW,
315 &blktime_threshold, 0,
316 "Number of seconds within is valid to block on a turnstile");
317 SYSCTL_INT(_debug_deadlkres, OID_AUTO, sleepfreq, CTLFLAG_RW, &sleepfreq, 0,
318 "Number of seconds between any deadlock resolver thread run");
319 #endif /* DEADLKRES */
322 read_cpu_time(long *cp_time)
327 /* Sum up global cp_time[]. */
328 bzero(cp_time, sizeof(long) * CPUSTATES);
331 for (j = 0; j < CPUSTATES; j++)
332 cp_time[j] += pc->pc_cp_time[j];
337 #include <sys/watchdog.h>
339 static int watchdog_ticks;
340 static int watchdog_enabled;
341 static void watchdog_fire(void);
342 static void watchdog_config(void *, u_int, int *);
343 #endif /* SW_WATCHDOG */
346 * Clock handling routines.
348 * This code is written to operate with two timers that run independently of
351 * The main timer, running hz times per second, is used to trigger interval
352 * timers, timeouts and rescheduling as needed.
354 * The second timer handles kernel and user profiling,
355 * and does resource use estimation. If the second timer is programmable,
356 * it is randomized to avoid aliasing between the two clocks. For example,
357 * the randomization prevents an adversary from always giving up the cpu
358 * just before its quantum expires. Otherwise, it would never accumulate
359 * cpu ticks. The mean frequency of the second timer is stathz.
361 * If no second timer exists, stathz will be zero; in this case we drive
362 * profiling and statistics off the main clock. This WILL NOT be accurate;
363 * do not do it unless absolutely necessary.
365 * The statistics clock may (or may not) be run at a higher rate while
366 * profiling. This profile clock runs at profhz. We require that profhz
367 * be an integral multiple of stathz.
369 * If the statistics clock is running fast, it must be divided by the ratio
370 * profhz/stathz for statistics. (For profiling, every tick counts.)
372 * Time-of-day is maintained using a "timecounter", which may or may
373 * not be related to the hardware generating the above mentioned
383 static DPCPU_DEFINE(int, pcputicks); /* Per-CPU version of ticks. */
384 static int global_hardclock_run = 0;
387 * Initialize clock frequencies and start both clocks running.
394 #ifdef EARLY_AP_STARTUP
401 * Set divisors to 1 (normal case) and let the machine-specific
404 mtx_init(&time_lock, "time lock", NULL, MTX_DEF);
408 * Compute profhz/stathz, and fix profhz if needed.
410 i = stathz ? stathz : hz;
413 psratio = profhz / i;
415 EVENTHANDLER_REGISTER(watchdog_list, watchdog_config, NULL, 0);
418 * Arrange for ticks to wrap 10 minutes after boot to help catch
419 * sign problems sooner.
421 ticks = INT_MAX - (hz * 10 * 60);
423 #ifdef EARLY_AP_STARTUP
425 * Fixup the tick counts in any blocked or sleeping threads to
426 * account for the jump above.
428 sx_slock(&allproc_lock);
429 FOREACH_PROC_IN_SYSTEM(p) {
431 if (p->p_state == PRS_NEW) {
435 FOREACH_THREAD_IN_PROC(p, td) {
437 if (TD_ON_LOCK(td)) {
438 MPASS(td->td_blktick == 0);
439 td->td_blktick = ticks;
441 if (TD_ON_SLEEPQ(td)) {
442 MPASS(td->td_slptick == 0);
443 td->td_slptick = ticks;
449 sx_sunlock(&allproc_lock);
454 * Each time the real-time timer fires, this function is called on all CPUs.
455 * Note that hardclock() calls hardclock_cpu() for the boot CPU, so only
456 * the other CPUs in the system need to call this function.
459 hardclock_cpu(int usermode)
461 struct pstats *pstats;
462 struct thread *td = curthread;
463 struct proc *p = td->td_proc;
467 * Run current process's virtual and profile time, as needed.
472 timevalisset(&pstats->p_timer[ITIMER_VIRTUAL].it_value)) {
474 if (itimerdecr(&pstats->p_timer[ITIMER_VIRTUAL], tick) == 0)
475 flags |= TDF_ALRMPEND | TDF_ASTPENDING;
478 if (timevalisset(&pstats->p_timer[ITIMER_PROF].it_value)) {
480 if (itimerdecr(&pstats->p_timer[ITIMER_PROF], tick) == 0)
481 flags |= TDF_PROFPEND | TDF_ASTPENDING;
485 td->td_flags |= flags;
489 if (PMC_CPU_HAS_SAMPLES(PCPU_GET(cpuid)))
490 PMC_CALL_HOOK_UNLOCKED(curthread, PMC_FN_DO_SAMPLES, NULL);
491 if (td->td_intr_frame != NULL)
492 PMC_SOFT_CALL_TF( , , clock, hard, td->td_intr_frame);
494 callout_process(sbinuptime());
498 * The real-time timer, interrupting hz times per second.
501 hardclock(int usermode, uintfptr_t pc)
504 atomic_add_int(&ticks, 1);
505 hardclock_cpu(usermode);
507 cpu_tick_calibration();
509 * If no separate statistics clock is available, run it from here.
511 * XXX: this only works for UP
514 profclock(usermode, pc);
517 #ifdef DEVICE_POLLING
518 hardclock_device_poll(); /* this is very short and quick */
519 #endif /* DEVICE_POLLING */
521 if (watchdog_enabled > 0 && --watchdog_ticks <= 0)
523 #endif /* SW_WATCHDOG */
527 hardclock_cnt(int cnt, int usermode)
529 struct pstats *pstats;
530 struct thread *td = curthread;
531 struct proc *p = td->td_proc;
532 int *t = DPCPU_PTR(pcputicks);
533 int flags, global, newticks;
536 #endif /* SW_WATCHDOG */
539 * Update per-CPU and possibly global ticks values.
544 newticks = *t - global;
551 } while (!atomic_cmpset_int(&ticks, global, *t));
554 * Run current process's virtual and profile time, as needed.
559 timevalisset(&pstats->p_timer[ITIMER_VIRTUAL].it_value)) {
561 if (itimerdecr(&pstats->p_timer[ITIMER_VIRTUAL],
563 flags |= TDF_ALRMPEND | TDF_ASTPENDING;
566 if (timevalisset(&pstats->p_timer[ITIMER_PROF].it_value)) {
568 if (itimerdecr(&pstats->p_timer[ITIMER_PROF],
570 flags |= TDF_PROFPEND | TDF_ASTPENDING;
575 td->td_flags |= flags;
580 if (PMC_CPU_HAS_SAMPLES(PCPU_GET(cpuid)))
581 PMC_CALL_HOOK_UNLOCKED(curthread, PMC_FN_DO_SAMPLES, NULL);
582 if (td->td_intr_frame != NULL)
583 PMC_SOFT_CALL_TF( , , clock, hard, td->td_intr_frame);
585 /* We are in charge to handle this tick duty. */
587 /* Dangerous and no need to call these things concurrently. */
588 if (atomic_cmpset_acq_int(&global_hardclock_run, 0, 1)) {
589 tc_ticktock(newticks);
590 #ifdef DEVICE_POLLING
591 /* This is very short and quick. */
592 hardclock_device_poll();
593 #endif /* DEVICE_POLLING */
594 atomic_store_rel_int(&global_hardclock_run, 0);
597 if (watchdog_enabled > 0) {
598 i = atomic_fetchadd_int(&watchdog_ticks, -newticks);
599 if (i > 0 && i <= newticks)
602 #endif /* SW_WATCHDOG */
604 if (curcpu == CPU_FIRST())
605 cpu_tick_calibration();
609 hardclock_sync(int cpu)
611 int *t = DPCPU_ID_PTR(cpu, pcputicks);
617 * Compute number of ticks in the specified amount of time.
623 register unsigned long ticks;
624 register long sec, usec;
627 * If the number of usecs in the whole seconds part of the time
628 * difference fits in a long, then the total number of usecs will
629 * fit in an unsigned long. Compute the total and convert it to
630 * ticks, rounding up and adding 1 to allow for the current tick
631 * to expire. Rounding also depends on unsigned long arithmetic
634 * Otherwise, if the number of ticks in the whole seconds part of
635 * the time difference fits in a long, then convert the parts to
636 * ticks separately and add, using similar rounding methods and
637 * overflow avoidance. This method would work in the previous
638 * case but it is slightly slower and assumes that hz is integral.
640 * Otherwise, round the time difference down to the maximum
641 * representable value.
643 * If ints have 32 bits, then the maximum value for any timeout in
644 * 10ms ticks is 248 days.
658 printf("tvotohz: negative time difference %ld sec %ld usec\n",
662 } else if (sec <= LONG_MAX / 1000000)
663 ticks = howmany(sec * 1000000 + (unsigned long)usec, tick) + 1;
664 else if (sec <= LONG_MAX / hz)
666 + howmany((unsigned long)usec, tick) + 1;
675 * Start profiling on a process.
677 * Kernel profiling passes proc0 which never exits and hence
678 * keeps the profile clock running constantly.
682 register struct proc *p;
685 PROC_LOCK_ASSERT(p, MA_OWNED);
686 if (p->p_flag & P_STOPPROF)
688 if ((p->p_flag & P_PROFIL) == 0) {
689 p->p_flag |= P_PROFIL;
690 mtx_lock(&time_lock);
691 if (++profprocs == 1)
692 cpu_startprofclock();
693 mtx_unlock(&time_lock);
698 * Stop profiling on a process.
702 register struct proc *p;
705 PROC_LOCK_ASSERT(p, MA_OWNED);
706 if (p->p_flag & P_PROFIL) {
707 if (p->p_profthreads != 0) {
708 while (p->p_profthreads != 0) {
709 p->p_flag |= P_STOPPROF;
710 msleep(&p->p_profthreads, &p->p_mtx, PPAUSE,
714 if ((p->p_flag & P_PROFIL) == 0)
716 p->p_flag &= ~P_PROFIL;
717 mtx_lock(&time_lock);
718 if (--profprocs == 0)
720 mtx_unlock(&time_lock);
725 * Statistics clock. Updates rusage information and calls the scheduler
726 * to adjust priorities of the active thread.
728 * This should be called by all active processors.
731 statclock(int usermode)
734 statclock_cnt(1, usermode);
738 statclock_cnt(int cnt, int usermode)
750 cp_time = (long *)PCPU_PTR(cp_time);
753 * Charge the time as appropriate.
755 td->td_uticks += cnt;
756 if (p->p_nice > NZERO)
757 cp_time[CP_NICE] += cnt;
759 cp_time[CP_USER] += cnt;
762 * Came from kernel mode, so we were:
763 * - handling an interrupt,
764 * - doing syscall or trap work on behalf of the current
766 * - spinning in the idle loop.
767 * Whichever it is, charge the time as appropriate.
768 * Note that we charge interrupts to the current process,
769 * regardless of whether they are ``for'' that process,
770 * so that we know how much of its real time was spent
771 * in ``non-process'' (i.e., interrupt) work.
773 if ((td->td_pflags & TDP_ITHREAD) ||
774 td->td_intr_nesting_level >= 2) {
775 td->td_iticks += cnt;
776 cp_time[CP_INTR] += cnt;
778 td->td_pticks += cnt;
779 td->td_sticks += cnt;
780 if (!TD_IS_IDLETHREAD(td))
781 cp_time[CP_SYS] += cnt;
783 cp_time[CP_IDLE] += cnt;
787 /* Update resource usage integrals and maximums. */
788 MPASS(p->p_vmspace != NULL);
791 ru->ru_ixrss += pgtok(vm->vm_tsize) * cnt;
792 ru->ru_idrss += pgtok(vm->vm_dsize) * cnt;
793 ru->ru_isrss += pgtok(vm->vm_ssize) * cnt;
794 rss = pgtok(vmspace_resident_count(vm));
795 if (ru->ru_maxrss < rss)
797 KTR_POINT2(KTR_SCHED, "thread", sched_tdname(td), "statclock",
798 "prio:%d", td->td_priority, "stathz:%d", (stathz)?stathz:hz);
799 SDT_PROBE2(sched, , , tick, td, td->td_proc);
800 thread_lock_flags(td, MTX_QUIET);
801 for ( ; cnt > 0; cnt--)
805 if (td->td_intr_frame != NULL)
806 PMC_SOFT_CALL_TF( , , clock, stat, td->td_intr_frame);
811 profclock(int usermode, uintfptr_t pc)
814 profclock_cnt(1, usermode, pc);
818 profclock_cnt(int cnt, int usermode, uintfptr_t pc)
829 * Came from user mode; CPU was in user state.
830 * If this process is being profiled, record the tick.
831 * if there is no related user location yet, don't
832 * bother trying to count it.
834 if (td->td_proc->p_flag & P_PROFIL)
835 addupc_intr(td, pc, cnt);
840 * Kernel statistics are just like addupc_intr, only easier.
843 if (g->state == GMON_PROF_ON && pc >= g->lowpc) {
845 if (i < g->textsize) {
852 if (td->td_intr_frame != NULL)
853 PMC_SOFT_CALL_TF( , , clock, prof, td->td_intr_frame);
858 * Return information about system clocks.
861 sysctl_kern_clockrate(SYSCTL_HANDLER_ARGS)
863 struct clockinfo clkinfo;
865 * Construct clockinfo structure.
867 bzero(&clkinfo, sizeof(clkinfo));
870 clkinfo.profhz = profhz;
871 clkinfo.stathz = stathz ? stathz : hz;
872 return (sysctl_handle_opaque(oidp, &clkinfo, sizeof clkinfo, req));
875 SYSCTL_PROC(_kern, KERN_CLOCKRATE, clockrate,
876 CTLTYPE_STRUCT|CTLFLAG_RD|CTLFLAG_MPSAFE,
877 0, 0, sysctl_kern_clockrate, "S,clockinfo",
878 "Rate and period of various kernel clocks");
883 watchdog_config(void *unused __unused, u_int cmd, int *error)
887 u = cmd & WD_INTERVAL;
888 if (u >= WD_TO_1SEC) {
889 watchdog_ticks = (1 << (u - WD_TO_1SEC)) * hz;
890 watchdog_enabled = 1;
893 watchdog_enabled = 0;
898 * Handle a watchdog timeout by dumping interrupt information and
899 * then either dropping to DDB or panicking.
912 nintr = sintrcnt / sizeof(u_long);
914 printf("interrupt total\n");
915 while (--nintr >= 0) {
917 printf("%-12s %20lu\n", curname, *curintr);
918 curname += strlen(curname) + 1;
919 inttotal += *curintr++;
921 printf("Total %20ju\n", (uintmax_t)inttotal);
923 #if defined(KDB) && !defined(KDB_UNATTENDED)
925 kdb_enter(KDB_WHY_WATCHDOG, "watchdog timeout");
927 panic("watchdog timeout");
931 #endif /* SW_WATCHDOG */