2 * SPDX-License-Identifier: BSD-3-Clause
4 * Copyright (c) 1982, 1986, 1991, 1993
5 * The Regents of the University of California. All rights reserved.
6 * (c) UNIX System Laboratories, Inc.
7 * All or some portions of this file are derived from material licensed
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33 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
36 * @(#)kern_clock.c 8.5 (Berkeley) 1/21/94
39 #include <sys/cdefs.h>
40 __FBSDID("$FreeBSD$");
43 #include "opt_device_polling.h"
44 #include "opt_hwpmc_hooks.h"
46 #include "opt_watchdog.h"
48 #include <sys/param.h>
49 #include <sys/systm.h>
50 #include <sys/callout.h>
51 #include <sys/epoch.h>
52 #include <sys/eventhandler.h>
53 #include <sys/gtaskqueue.h>
55 #include <sys/kernel.h>
56 #include <sys/kthread.h>
59 #include <sys/mutex.h>
61 #include <sys/resource.h>
62 #include <sys/resourcevar.h>
63 #include <sys/sched.h>
65 #include <sys/signalvar.h>
66 #include <sys/sleepqueue.h>
70 #include <vm/vm_map.h>
71 #include <sys/sysctl.h>
73 #include <sys/interrupt.h>
74 #include <sys/limits.h>
75 #include <sys/timetc.h>
82 #include <sys/pmckern.h>
83 PMC_SOFT_DEFINE( , , clock, hard);
84 PMC_SOFT_DEFINE( , , clock, stat);
85 PMC_SOFT_DEFINE_EX( , , clock, prof, \
86 cpu_startprofclock, cpu_stopprofclock);
90 extern void hardclock_device_poll(void);
91 #endif /* DEVICE_POLLING */
93 static void initclocks(void *dummy);
94 SYSINIT(clocks, SI_SUB_CLOCKS, SI_ORDER_FIRST, initclocks, NULL);
96 /* Spin-lock protecting profiling statistics. */
97 static struct mtx time_lock;
99 SDT_PROVIDER_DECLARE(sched);
100 SDT_PROBE_DEFINE2(sched, , , tick, "struct thread *", "struct proc *");
103 sysctl_kern_cp_time(SYSCTL_HANDLER_ARGS)
106 long cp_time[CPUSTATES];
109 unsigned int cp_time32[CPUSTATES];
112 read_cpu_time(cp_time);
114 if (req->flags & SCTL_MASK32) {
116 return SYSCTL_OUT(req, 0, sizeof(cp_time32));
117 for (i = 0; i < CPUSTATES; i++)
118 cp_time32[i] = (unsigned int)cp_time[i];
119 error = SYSCTL_OUT(req, cp_time32, sizeof(cp_time32));
124 return SYSCTL_OUT(req, 0, sizeof(cp_time));
125 error = SYSCTL_OUT(req, cp_time, sizeof(cp_time));
130 SYSCTL_PROC(_kern, OID_AUTO, cp_time, CTLTYPE_LONG|CTLFLAG_RD|CTLFLAG_MPSAFE,
131 0,0, sysctl_kern_cp_time, "LU", "CPU time statistics");
133 static long empty[CPUSTATES];
136 sysctl_kern_cp_times(SYSCTL_HANDLER_ARGS)
143 unsigned int cp_time32[CPUSTATES];
149 if (req->flags & SCTL_MASK32)
150 return SYSCTL_OUT(req, 0, sizeof(cp_time32) * (mp_maxid + 1));
153 return SYSCTL_OUT(req, 0, sizeof(long) * CPUSTATES * (mp_maxid + 1));
155 for (error = 0, c = 0; error == 0 && c <= mp_maxid; c++) {
156 if (!CPU_ABSENT(c)) {
158 cp_time = pcpu->pc_cp_time;
163 if (req->flags & SCTL_MASK32) {
164 for (i = 0; i < CPUSTATES; i++)
165 cp_time32[i] = (unsigned int)cp_time[i];
166 error = SYSCTL_OUT(req, cp_time32, sizeof(cp_time32));
169 error = SYSCTL_OUT(req, cp_time, sizeof(long) * CPUSTATES);
174 SYSCTL_PROC(_kern, OID_AUTO, cp_times, CTLTYPE_LONG|CTLFLAG_RD|CTLFLAG_MPSAFE,
175 0,0, sysctl_kern_cp_times, "LU", "per-CPU time statistics");
178 static const char *blessed[] = {
184 static int slptime_threshold = 1800;
185 static int blktime_threshold = 900;
186 static int sleepfreq = 3;
189 deadlres_td_on_lock(struct proc *p, struct thread *td, int blkticks)
193 sx_assert(&allproc_lock, SX_LOCKED);
194 PROC_LOCK_ASSERT(p, MA_OWNED);
195 THREAD_LOCK_ASSERT(td, MA_OWNED);
197 * The thread should be blocked on a turnstile, simply check
198 * if the turnstile channel is in good state.
200 MPASS(td->td_blocked != NULL);
202 tticks = ticks - td->td_blktick;
203 if (tticks > blkticks)
205 * Accordingly with provided thresholds, this thread is stuck
206 * for too long on a turnstile.
208 panic("%s: possible deadlock detected for %p (%s), "
209 "blocked for %d ticks\n", __func__,
210 td, sched_tdname(td), tticks);
214 deadlres_td_sleep_q(struct proc *p, struct thread *td, int slpticks)
217 int i, slptype, tticks;
219 sx_assert(&allproc_lock, SX_LOCKED);
220 PROC_LOCK_ASSERT(p, MA_OWNED);
221 THREAD_LOCK_ASSERT(td, MA_OWNED);
223 * Check if the thread is sleeping on a lock, otherwise skip the check.
224 * Drop the thread lock in order to avoid a LOR with the sleepqueue
227 wchan = td->td_wchan;
228 tticks = ticks - td->td_slptick;
229 slptype = sleepq_type(wchan);
230 if ((slptype == SLEEPQ_SX || slptype == SLEEPQ_LK) &&
234 * Accordingly with provided thresholds, this thread is stuck
235 * for too long on a sleepqueue.
236 * However, being on a sleepqueue, we might still check for the
239 for (i = 0; blessed[i] != NULL; i++)
240 if (!strcmp(blessed[i], td->td_wmesg))
243 panic("%s: possible deadlock detected for %p (%s), "
244 "blocked for %d ticks\n", __func__,
245 td, sched_tdname(td), tticks);
254 int blkticks, slpticks, tryl;
258 blkticks = blktime_threshold * hz;
259 slpticks = slptime_threshold * hz;
262 * Avoid to sleep on the sx_lock in order to avoid a
263 * possible priority inversion problem leading to
265 * If the lock can't be held after 100 tries, panic.
267 if (!sx_try_slock(&allproc_lock)) {
269 panic("%s: possible deadlock detected "
270 "on allproc_lock\n", __func__);
272 pause("allproc", sleepfreq * hz);
276 FOREACH_PROC_IN_SYSTEM(p) {
278 if (p->p_state == PRS_NEW) {
282 FOREACH_THREAD_IN_PROC(p, td) {
285 deadlres_td_on_lock(p, td,
287 else if (TD_IS_SLEEPING(td))
288 deadlres_td_sleep_q(p, td,
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 | CTLFLAG_MPSAFE, 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];
336 #include <sys/watchdog.h>
338 static int watchdog_ticks;
339 static int watchdog_enabled;
340 static void watchdog_fire(void);
341 static void watchdog_config(void *, u_int, int *);
344 watchdog_attach(void)
346 EVENTHANDLER_REGISTER(watchdog_list, watchdog_config, NULL, 0);
350 * Clock handling routines.
352 * This code is written to operate with two timers that run independently of
355 * The main timer, running hz times per second, is used to trigger interval
356 * timers, timeouts and rescheduling as needed.
358 * The second timer handles kernel and user profiling,
359 * and does resource use estimation. If the second timer is programmable,
360 * it is randomized to avoid aliasing between the two clocks. For example,
361 * the randomization prevents an adversary from always giving up the cpu
362 * just before its quantum expires. Otherwise, it would never accumulate
363 * cpu ticks. The mean frequency of the second timer is stathz.
365 * If no second timer exists, stathz will be zero; in this case we drive
366 * profiling and statistics off the main clock. This WILL NOT be accurate;
367 * do not do it unless absolutely necessary.
369 * The statistics clock may (or may not) be run at a higher rate while
370 * profiling. This profile clock runs at profhz. We require that profhz
371 * be an integral multiple of stathz.
373 * If the statistics clock is running fast, it must be divided by the ratio
374 * profhz/stathz for statistics. (For profiling, every tick counts.)
376 * Time-of-day is maintained using a "timecounter", which may or may
377 * not be related to the hardware generating the above mentioned
387 DPCPU_DEFINE_STATIC(int, pcputicks); /* Per-CPU version of ticks. */
388 #ifdef DEVICE_POLLING
389 static int devpoll_run = 0;
393 * Initialize clock frequencies and start both clocks running.
397 initclocks(void *dummy)
402 * Set divisors to 1 (normal case) and let the machine-specific
405 mtx_init(&time_lock, "time lock", NULL, MTX_DEF);
409 * Compute profhz/stathz, and fix profhz if needed.
411 i = stathz ? stathz : hz;
414 psratio = profhz / i;
417 /* Enable hardclock watchdog now, even if a hardware watchdog exists. */
420 /* Volunteer to run a software watchdog. */
421 if (wdog_software_attach == NULL)
422 wdog_software_attach = watchdog_attach;
426 static __noinline void
427 hardclock_itimer(struct thread *td, struct pstats *pstats, int cnt, int usermode)
435 timevalisset(&pstats->p_timer[ITIMER_VIRTUAL].it_value)) {
437 if (itimerdecr(&pstats->p_timer[ITIMER_VIRTUAL],
439 flags |= TDF_ALRMPEND | TDF_ASTPENDING;
442 if (timevalisset(&pstats->p_timer[ITIMER_PROF].it_value)) {
444 if (itimerdecr(&pstats->p_timer[ITIMER_PROF],
446 flags |= TDF_PROFPEND | TDF_ASTPENDING;
451 td->td_flags |= flags;
457 hardclock(int cnt, int usermode)
459 struct pstats *pstats;
460 struct thread *td = curthread;
461 struct proc *p = td->td_proc;
462 int *t = DPCPU_PTR(pcputicks);
463 int global, i, newticks;
466 * Update per-CPU and possibly global ticks values.
471 newticks = *t - global;
478 } while (!atomic_fcmpset_int(&ticks, &global, *t));
481 * Run current process's virtual and profile time, as needed.
485 timevalisset(&pstats->p_timer[ITIMER_VIRTUAL].it_value) ||
486 timevalisset(&pstats->p_timer[ITIMER_PROF].it_value)))
487 hardclock_itimer(td, pstats, cnt, usermode);
490 if (PMC_CPU_HAS_SAMPLES(PCPU_GET(cpuid)))
491 PMC_CALL_HOOK_UNLOCKED(curthread, PMC_FN_DO_SAMPLES, NULL);
492 if (td->td_intr_frame != NULL)
493 PMC_SOFT_CALL_TF( , , clock, hard, td->td_intr_frame);
495 /* We are in charge to handle this tick duty. */
497 tc_ticktock(newticks);
498 #ifdef DEVICE_POLLING
499 /* Dangerous and no need to call these things concurrently. */
500 if (atomic_cmpset_acq_int(&devpoll_run, 0, 1)) {
501 /* This is very short and quick. */
502 hardclock_device_poll();
503 atomic_store_rel_int(&devpoll_run, 0);
505 #endif /* DEVICE_POLLING */
506 if (watchdog_enabled > 0) {
507 i = atomic_fetchadd_int(&watchdog_ticks, -newticks);
508 if (i > 0 && i <= newticks)
511 intr_event_handle(clk_intr_event, NULL);
513 if (curcpu == CPU_FIRST())
514 cpu_tick_calibration();
515 if (__predict_false(DPCPU_GET(epoch_cb_count)))
516 GROUPTASK_ENQUEUE(DPCPU_PTR(epoch_cb_task));
520 hardclock_sync(int cpu)
523 KASSERT(!CPU_ABSENT(cpu), ("Absent CPU %d", cpu));
524 t = DPCPU_ID_PTR(cpu, pcputicks);
530 * Compute number of ticks in the specified amount of time.
533 tvtohz(struct timeval *tv)
539 * If the number of usecs in the whole seconds part of the time
540 * difference fits in a long, then the total number of usecs will
541 * fit in an unsigned long. Compute the total and convert it to
542 * ticks, rounding up and adding 1 to allow for the current tick
543 * to expire. Rounding also depends on unsigned long arithmetic
546 * Otherwise, if the number of ticks in the whole seconds part of
547 * the time difference fits in a long, then convert the parts to
548 * ticks separately and add, using similar rounding methods and
549 * overflow avoidance. This method would work in the previous
550 * case but it is slightly slower and assumes that hz is integral.
552 * Otherwise, round the time difference down to the maximum
553 * representable value.
555 * If ints have 32 bits, then the maximum value for any timeout in
556 * 10ms ticks is 248 days.
570 printf("tvotohz: negative time difference %ld sec %ld usec\n",
574 } else if (sec <= LONG_MAX / 1000000)
575 ticks = howmany(sec * 1000000 + (unsigned long)usec, tick) + 1;
576 else if (sec <= LONG_MAX / hz)
578 + howmany((unsigned long)usec, tick) + 1;
587 * Start profiling on a process.
589 * Kernel profiling passes proc0 which never exits and hence
590 * keeps the profile clock running constantly.
593 startprofclock(struct proc *p)
596 PROC_LOCK_ASSERT(p, MA_OWNED);
597 if (p->p_flag & P_STOPPROF)
599 if ((p->p_flag & P_PROFIL) == 0) {
600 p->p_flag |= P_PROFIL;
601 mtx_lock(&time_lock);
602 if (++profprocs == 1)
603 cpu_startprofclock();
604 mtx_unlock(&time_lock);
609 * Stop profiling on a process.
612 stopprofclock(struct proc *p)
615 PROC_LOCK_ASSERT(p, MA_OWNED);
616 if (p->p_flag & P_PROFIL) {
617 if (p->p_profthreads != 0) {
618 while (p->p_profthreads != 0) {
619 p->p_flag |= P_STOPPROF;
620 msleep(&p->p_profthreads, &p->p_mtx, PPAUSE,
624 if ((p->p_flag & P_PROFIL) == 0)
626 p->p_flag &= ~P_PROFIL;
627 mtx_lock(&time_lock);
628 if (--profprocs == 0)
630 mtx_unlock(&time_lock);
635 * Statistics clock. Updates rusage information and calls the scheduler
636 * to adjust priorities of the active thread.
638 * This should be called by all active processors.
641 statclock(int cnt, int usermode)
649 uint64_t runtime, new_switchtime;
654 cp_time = (long *)PCPU_PTR(cp_time);
657 * Charge the time as appropriate.
659 td->td_uticks += cnt;
660 if (p->p_nice > NZERO)
661 cp_time[CP_NICE] += cnt;
663 cp_time[CP_USER] += cnt;
666 * Came from kernel mode, so we were:
667 * - handling an interrupt,
668 * - doing syscall or trap work on behalf of the current
670 * - spinning in the idle loop.
671 * Whichever it is, charge the time as appropriate.
672 * Note that we charge interrupts to the current process,
673 * regardless of whether they are ``for'' that process,
674 * so that we know how much of its real time was spent
675 * in ``non-process'' (i.e., interrupt) work.
677 if ((td->td_pflags & TDP_ITHREAD) ||
678 td->td_intr_nesting_level >= 2) {
679 td->td_iticks += cnt;
680 cp_time[CP_INTR] += cnt;
682 td->td_pticks += cnt;
683 td->td_sticks += cnt;
684 if (!TD_IS_IDLETHREAD(td))
685 cp_time[CP_SYS] += cnt;
687 cp_time[CP_IDLE] += cnt;
691 /* Update resource usage integrals and maximums. */
692 MPASS(p->p_vmspace != NULL);
695 ru->ru_ixrss += pgtok(vm->vm_tsize) * cnt;
696 ru->ru_idrss += pgtok(vm->vm_dsize) * cnt;
697 ru->ru_isrss += pgtok(vm->vm_ssize) * cnt;
698 rss = pgtok(vmspace_resident_count(vm));
699 if (ru->ru_maxrss < rss)
701 KTR_POINT2(KTR_SCHED, "thread", sched_tdname(td), "statclock",
702 "prio:%d", td->td_priority, "stathz:%d", (stathz)?stathz:hz);
703 SDT_PROBE2(sched, , , tick, td, td->td_proc);
704 thread_lock_flags(td, MTX_QUIET);
707 * Compute the amount of time during which the current
708 * thread was running, and add that to its total so far.
710 new_switchtime = cpu_ticks();
711 runtime = new_switchtime - PCPU_GET(switchtime);
712 td->td_runtime += runtime;
713 td->td_incruntime += runtime;
714 PCPU_SET(switchtime, new_switchtime);
716 sched_clock(td, cnt);
719 if (td->td_intr_frame != NULL)
720 PMC_SOFT_CALL_TF( , , clock, stat, td->td_intr_frame);
725 profclock(int cnt, int usermode, uintfptr_t pc)
736 * Came from user mode; CPU was in user state.
737 * If this process is being profiled, record the tick.
738 * if there is no related user location yet, don't
739 * bother trying to count it.
741 if (td->td_proc->p_flag & P_PROFIL)
742 addupc_intr(td, pc, cnt);
747 * Kernel statistics are just like addupc_intr, only easier.
750 if (g->state == GMON_PROF_ON && pc >= g->lowpc) {
752 if (i < g->textsize) {
759 if (td->td_intr_frame != NULL)
760 PMC_SOFT_CALL_TF( , , clock, prof, td->td_intr_frame);
765 * Return information about system clocks.
768 sysctl_kern_clockrate(SYSCTL_HANDLER_ARGS)
770 struct clockinfo clkinfo;
772 * Construct clockinfo structure.
774 bzero(&clkinfo, sizeof(clkinfo));
777 clkinfo.profhz = profhz;
778 clkinfo.stathz = stathz ? stathz : hz;
779 return (sysctl_handle_opaque(oidp, &clkinfo, sizeof clkinfo, req));
782 SYSCTL_PROC(_kern, KERN_CLOCKRATE, clockrate,
783 CTLTYPE_STRUCT|CTLFLAG_RD|CTLFLAG_MPSAFE,
784 0, 0, sysctl_kern_clockrate, "S,clockinfo",
785 "Rate and period of various kernel clocks");
788 watchdog_config(void *unused __unused, u_int cmd, int *error)
792 u = cmd & WD_INTERVAL;
793 if (u >= WD_TO_1SEC) {
794 watchdog_ticks = (1 << (u - WD_TO_1SEC)) * hz;
795 watchdog_enabled = 1;
798 watchdog_enabled = 0;
803 * Handle a watchdog timeout by dumping interrupt information and
804 * then either dropping to DDB or panicking.
817 nintr = sintrcnt / sizeof(u_long);
819 printf("interrupt total\n");
820 while (--nintr >= 0) {
822 printf("%-12s %20lu\n", curname, *curintr);
823 curname += strlen(curname) + 1;
824 inttotal += *curintr++;
826 printf("Total %20ju\n", (uintmax_t)inttotal);
828 #if defined(KDB) && !defined(KDB_UNATTENDED)
830 kdb_enter(KDB_WHY_WATCHDOG, "watchdog timeout");
832 panic("watchdog timeout");