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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>
59 #include <sys/signalvar.h>
60 #include <sys/sleepqueue.h>
64 #include <vm/vm_map.h>
65 #include <sys/sysctl.h>
67 #include <sys/interrupt.h>
68 #include <sys/limits.h>
69 #include <sys/timetc.h>
76 #include <sys/pmckern.h>
80 extern void hardclock_device_poll(void);
81 #endif /* DEVICE_POLLING */
83 static void initclocks(void *dummy);
84 SYSINIT(clocks, SI_SUB_CLOCKS, SI_ORDER_FIRST, initclocks, NULL);
86 /* Spin-lock protecting profiling statistics. */
87 static struct mtx time_lock;
90 sysctl_kern_cp_time(SYSCTL_HANDLER_ARGS)
93 long cp_time[CPUSTATES];
96 unsigned int cp_time32[CPUSTATES];
99 read_cpu_time(cp_time);
101 if (req->flags & SCTL_MASK32) {
103 return SYSCTL_OUT(req, 0, sizeof(cp_time32));
104 for (i = 0; i < CPUSTATES; i++)
105 cp_time32[i] = (unsigned int)cp_time[i];
106 error = SYSCTL_OUT(req, cp_time32, sizeof(cp_time32));
111 return SYSCTL_OUT(req, 0, sizeof(cp_time));
112 error = SYSCTL_OUT(req, cp_time, sizeof(cp_time));
117 SYSCTL_PROC(_kern, OID_AUTO, cp_time, CTLTYPE_LONG|CTLFLAG_RD|CTLFLAG_MPSAFE,
118 0,0, sysctl_kern_cp_time, "LU", "CPU time statistics");
120 static long empty[CPUSTATES];
123 sysctl_kern_cp_times(SYSCTL_HANDLER_ARGS)
130 unsigned int cp_time32[CPUSTATES];
136 if (req->flags & SCTL_MASK32)
137 return SYSCTL_OUT(req, 0, sizeof(cp_time32) * (mp_maxid + 1));
140 return SYSCTL_OUT(req, 0, sizeof(long) * CPUSTATES * (mp_maxid + 1));
142 for (error = 0, c = 0; error == 0 && c <= mp_maxid; c++) {
143 if (!CPU_ABSENT(c)) {
145 cp_time = pcpu->pc_cp_time;
150 if (req->flags & SCTL_MASK32) {
151 for (i = 0; i < CPUSTATES; i++)
152 cp_time32[i] = (unsigned int)cp_time[i];
153 error = SYSCTL_OUT(req, cp_time32, sizeof(cp_time32));
156 error = SYSCTL_OUT(req, cp_time, sizeof(long) * CPUSTATES);
161 SYSCTL_PROC(_kern, OID_AUTO, cp_times, CTLTYPE_LONG|CTLFLAG_RD|CTLFLAG_MPSAFE,
162 0,0, sysctl_kern_cp_times, "LU", "per-CPU time statistics");
165 static const char *blessed[] = {
171 static int slptime_threshold = 1800;
172 static int blktime_threshold = 900;
173 static int sleepfreq = 3;
181 int blkticks, i, slpticks, slptype, tryl, tticks;
185 blkticks = blktime_threshold * hz;
186 slpticks = slptime_threshold * hz;
189 * Avoid to sleep on the sx_lock in order to avoid a possible
190 * priority inversion problem leading to starvation.
191 * If the lock can't be held after 100 tries, panic.
193 if (!sx_try_slock(&allproc_lock)) {
195 panic("%s: possible deadlock detected on allproc_lock\n",
198 pause("allproc_lock deadlkres", sleepfreq * hz);
202 FOREACH_PROC_IN_SYSTEM(p) {
204 FOREACH_THREAD_IN_PROC(p, td) {
207 * Once a thread is found in "interesting"
208 * state a possible ticks wrap-up needs to be
212 if (TD_ON_LOCK(td) && ticks < td->td_blktick) {
215 * The thread should be blocked on a
216 * turnstile, simply check if the
217 * turnstile channel is in good state.
219 MPASS(td->td_blocked != NULL);
221 tticks = ticks - td->td_blktick;
223 if (tticks > blkticks) {
226 * Accordingly with provided
227 * thresholds, this thread is
228 * stuck for too long on a
232 sx_sunlock(&allproc_lock);
233 panic("%s: possible deadlock detected for %p, blocked for %d ticks\n",
234 __func__, td, tticks);
236 } else if (TD_IS_SLEEPING(td) &&
238 ticks < td->td_blktick) {
241 * Check if the thread is sleeping on a
242 * lock, otherwise skip the check.
243 * Drop the thread lock in order to
244 * avoid a LOR with the sleepqueue
247 wchan = td->td_wchan;
248 tticks = ticks - td->td_slptick;
250 slptype = sleepq_type(wchan);
251 if ((slptype == SLEEPQ_SX ||
252 slptype == SLEEPQ_LK) &&
256 * Accordingly with provided
257 * thresholds, this thread is
258 * stuck for too long on a
260 * However, being on a
261 * sleepqueue, we might still
262 * check for the blessed
266 for (i = 0; blessed[i] != NULL;
268 if (!strcmp(blessed[i],
279 sx_sunlock(&allproc_lock);
280 panic("%s: possible deadlock detected for %p, blocked for %d ticks\n",
281 __func__, td, tticks);
288 sx_sunlock(&allproc_lock);
290 /* Sleep for sleepfreq seconds. */
291 pause("deadlkres", sleepfreq * hz);
295 static struct kthread_desc deadlkres_kd = {
298 (struct thread **)NULL
301 SYSINIT(deadlkres, SI_SUB_CLOCKS, SI_ORDER_ANY, kthread_start, &deadlkres_kd);
303 SYSCTL_NODE(_debug, OID_AUTO, deadlkres, CTLFLAG_RW, 0, "Deadlock resolver");
304 SYSCTL_INT(_debug_deadlkres, OID_AUTO, slptime_threshold, CTLFLAG_RW,
305 &slptime_threshold, 0,
306 "Number of seconds within is valid to sleep on a sleepqueue");
307 SYSCTL_INT(_debug_deadlkres, OID_AUTO, blktime_threshold, CTLFLAG_RW,
308 &blktime_threshold, 0,
309 "Number of seconds within is valid to block on a turnstile");
310 SYSCTL_INT(_debug_deadlkres, OID_AUTO, sleepfreq, CTLFLAG_RW, &sleepfreq, 0,
311 "Number of seconds between any deadlock resolver thread run");
312 #endif /* DEADLKRES */
315 read_cpu_time(long *cp_time)
320 /* Sum up global cp_time[]. */
321 bzero(cp_time, sizeof(long) * CPUSTATES);
324 for (j = 0; j < CPUSTATES; j++)
325 cp_time[j] += pc->pc_cp_time[j];
330 #include <sys/watchdog.h>
332 static int watchdog_ticks;
333 static int watchdog_enabled;
334 static void watchdog_fire(void);
335 static void watchdog_config(void *, u_int, int *);
336 #endif /* SW_WATCHDOG */
339 * Clock handling routines.
341 * This code is written to operate with two timers that run independently of
344 * The main timer, running hz times per second, is used to trigger interval
345 * timers, timeouts and rescheduling as needed.
347 * The second timer handles kernel and user profiling,
348 * and does resource use estimation. If the second timer is programmable,
349 * it is randomized to avoid aliasing between the two clocks. For example,
350 * the randomization prevents an adversary from always giving up the cpu
351 * just before its quantum expires. Otherwise, it would never accumulate
352 * cpu ticks. The mean frequency of the second timer is stathz.
354 * If no second timer exists, stathz will be zero; in this case we drive
355 * profiling and statistics off the main clock. This WILL NOT be accurate;
356 * do not do it unless absolutely necessary.
358 * The statistics clock may (or may not) be run at a higher rate while
359 * profiling. This profile clock runs at profhz. We require that profhz
360 * be an integral multiple of stathz.
362 * If the statistics clock is running fast, it must be divided by the ratio
363 * profhz/stathz for statistics. (For profiling, every tick counts.)
365 * Time-of-day is maintained using a "timecounter", which may or may
366 * not be related to the hardware generating the above mentioned
376 static DPCPU_DEFINE(int, pcputicks); /* Per-CPU version of ticks. */
377 static int global_hardclock_run = 0;
380 * Initialize clock frequencies and start both clocks running.
390 * Set divisors to 1 (normal case) and let the machine-specific
393 mtx_init(&time_lock, "time lock", NULL, MTX_DEF);
397 * Compute profhz/stathz, and fix profhz if needed.
399 i = stathz ? stathz : hz;
402 psratio = profhz / i;
404 EVENTHANDLER_REGISTER(watchdog_list, watchdog_config, NULL, 0);
409 * Each time the real-time timer fires, this function is called on all CPUs.
410 * Note that hardclock() calls hardclock_cpu() for the boot CPU, so only
411 * the other CPUs in the system need to call this function.
414 hardclock_cpu(int usermode)
416 struct pstats *pstats;
417 struct thread *td = curthread;
418 struct proc *p = td->td_proc;
422 * Run current process's virtual and profile time, as needed.
427 timevalisset(&pstats->p_timer[ITIMER_VIRTUAL].it_value)) {
429 if (itimerdecr(&pstats->p_timer[ITIMER_VIRTUAL], tick) == 0)
430 flags |= TDF_ALRMPEND | TDF_ASTPENDING;
433 if (timevalisset(&pstats->p_timer[ITIMER_PROF].it_value)) {
435 if (itimerdecr(&pstats->p_timer[ITIMER_PROF], tick) == 0)
436 flags |= TDF_PROFPEND | TDF_ASTPENDING;
441 td->td_flags |= flags;
445 if (PMC_CPU_HAS_SAMPLES(PCPU_GET(cpuid)))
446 PMC_CALL_HOOK_UNLOCKED(curthread, PMC_FN_DO_SAMPLES, NULL);
452 * The real-time timer, interrupting hz times per second.
455 hardclock(int usermode, uintfptr_t pc)
458 atomic_add_int((volatile int *)&ticks, 1);
459 hardclock_cpu(usermode);
461 cpu_tick_calibration();
463 * If no separate statistics clock is available, run it from here.
465 * XXX: this only works for UP
468 profclock(usermode, pc);
471 #ifdef DEVICE_POLLING
472 hardclock_device_poll(); /* this is very short and quick */
473 #endif /* DEVICE_POLLING */
475 if (watchdog_enabled > 0 && --watchdog_ticks <= 0)
477 #endif /* SW_WATCHDOG */
481 hardclock_anycpu(int cnt, int usermode)
483 struct pstats *pstats;
484 struct thread *td = curthread;
485 struct proc *p = td->td_proc;
486 int *t = DPCPU_PTR(pcputicks);
487 int flags, global, newticks;
490 #endif /* SW_WATCHDOG */
493 * Update per-CPU and possibly global ticks values.
498 newticks = *t - global;
505 } while (!atomic_cmpset_int(&ticks, global, *t));
508 * Run current process's virtual and profile time, as needed.
513 timevalisset(&pstats->p_timer[ITIMER_VIRTUAL].it_value)) {
515 if (itimerdecr(&pstats->p_timer[ITIMER_VIRTUAL],
517 flags |= TDF_ALRMPEND | TDF_ASTPENDING;
520 if (timevalisset(&pstats->p_timer[ITIMER_PROF].it_value)) {
522 if (itimerdecr(&pstats->p_timer[ITIMER_PROF],
524 flags |= TDF_PROFPEND | TDF_ASTPENDING;
529 td->td_flags |= flags;
533 if (PMC_CPU_HAS_SAMPLES(PCPU_GET(cpuid)))
534 PMC_CALL_HOOK_UNLOCKED(curthread, PMC_FN_DO_SAMPLES, NULL);
537 /* We are in charge to handle this tick duty. */
539 /* Dangerous and no need to call these things concurrently. */
540 if (atomic_cmpset_acq_int(&global_hardclock_run, 0, 1)) {
541 tc_ticktock(newticks);
542 #ifdef DEVICE_POLLING
543 /* This is very short and quick. */
544 hardclock_device_poll();
545 #endif /* DEVICE_POLLING */
546 atomic_store_rel_int(&global_hardclock_run, 0);
549 if (watchdog_enabled > 0) {
550 i = atomic_fetchadd_int(&watchdog_ticks, -newticks);
551 if (i > 0 && i <= newticks)
554 #endif /* SW_WATCHDOG */
556 if (curcpu == CPU_FIRST())
557 cpu_tick_calibration();
561 hardclock_sync(int cpu)
563 int *t = DPCPU_ID_PTR(cpu, pcputicks);
569 * Compute number of ticks in the specified amount of time.
575 register unsigned long ticks;
576 register long sec, usec;
579 * If the number of usecs in the whole seconds part of the time
580 * difference fits in a long, then the total number of usecs will
581 * fit in an unsigned long. Compute the total and convert it to
582 * ticks, rounding up and adding 1 to allow for the current tick
583 * to expire. Rounding also depends on unsigned long arithmetic
586 * Otherwise, if the number of ticks in the whole seconds part of
587 * the time difference fits in a long, then convert the parts to
588 * ticks separately and add, using similar rounding methods and
589 * overflow avoidance. This method would work in the previous
590 * case but it is slightly slower and assumes that hz is integral.
592 * Otherwise, round the time difference down to the maximum
593 * representable value.
595 * If ints have 32 bits, then the maximum value for any timeout in
596 * 10ms ticks is 248 days.
610 printf("tvotohz: negative time difference %ld sec %ld usec\n",
614 } else if (sec <= LONG_MAX / 1000000)
615 ticks = (sec * 1000000 + (unsigned long)usec + (tick - 1))
617 else if (sec <= LONG_MAX / hz)
619 + ((unsigned long)usec + (tick - 1)) / tick + 1;
628 * Start profiling on a process.
630 * Kernel profiling passes proc0 which never exits and hence
631 * keeps the profile clock running constantly.
635 register struct proc *p;
638 PROC_LOCK_ASSERT(p, MA_OWNED);
639 if (p->p_flag & P_STOPPROF)
641 if ((p->p_flag & P_PROFIL) == 0) {
642 p->p_flag |= P_PROFIL;
643 mtx_lock(&time_lock);
644 if (++profprocs == 1)
645 cpu_startprofclock();
646 mtx_unlock(&time_lock);
651 * Stop profiling on a process.
655 register struct proc *p;
658 PROC_LOCK_ASSERT(p, MA_OWNED);
659 if (p->p_flag & P_PROFIL) {
660 if (p->p_profthreads != 0) {
661 p->p_flag |= P_STOPPROF;
662 while (p->p_profthreads != 0)
663 msleep(&p->p_profthreads, &p->p_mtx, PPAUSE,
665 p->p_flag &= ~P_STOPPROF;
667 if ((p->p_flag & P_PROFIL) == 0)
669 p->p_flag &= ~P_PROFIL;
670 mtx_lock(&time_lock);
671 if (--profprocs == 0)
673 mtx_unlock(&time_lock);
678 * Statistics clock. Updates rusage information and calls the scheduler
679 * to adjust priorities of the active thread.
681 * This should be called by all active processors.
684 statclock(int usermode)
696 cp_time = (long *)PCPU_PTR(cp_time);
699 * Charge the time as appropriate.
702 if (p->p_nice > NZERO)
708 * Came from kernel mode, so we were:
709 * - handling an interrupt,
710 * - doing syscall or trap work on behalf of the current
712 * - spinning in the idle loop.
713 * Whichever it is, charge the time as appropriate.
714 * Note that we charge interrupts to the current process,
715 * regardless of whether they are ``for'' that process,
716 * so that we know how much of its real time was spent
717 * in ``non-process'' (i.e., interrupt) work.
719 if ((td->td_pflags & TDP_ITHREAD) ||
720 td->td_intr_nesting_level >= 2) {
726 if (!TD_IS_IDLETHREAD(td))
733 /* Update resource usage integrals and maximums. */
734 MPASS(p->p_vmspace != NULL);
737 ru->ru_ixrss += pgtok(vm->vm_tsize);
738 ru->ru_idrss += pgtok(vm->vm_dsize);
739 ru->ru_isrss += pgtok(vm->vm_ssize);
740 rss = pgtok(vmspace_resident_count(vm));
741 if (ru->ru_maxrss < rss)
743 KTR_POINT2(KTR_SCHED, "thread", sched_tdname(td), "statclock",
744 "prio:%d", td->td_priority, "stathz:%d", (stathz)?stathz:hz);
745 thread_lock_flags(td, MTX_QUIET);
751 profclock(int usermode, uintfptr_t pc)
762 * Came from user mode; CPU was in user state.
763 * If this process is being profiled, record the tick.
764 * if there is no related user location yet, don't
765 * bother trying to count it.
767 if (td->td_proc->p_flag & P_PROFIL)
768 addupc_intr(td, pc, 1);
773 * Kernel statistics are just like addupc_intr, only easier.
776 if (g->state == GMON_PROF_ON && pc >= g->lowpc) {
778 if (i < g->textsize) {
787 * Return information about system clocks.
790 sysctl_kern_clockrate(SYSCTL_HANDLER_ARGS)
792 struct clockinfo clkinfo;
794 * Construct clockinfo structure.
796 bzero(&clkinfo, sizeof(clkinfo));
799 clkinfo.profhz = profhz;
800 clkinfo.stathz = stathz ? stathz : hz;
801 return (sysctl_handle_opaque(oidp, &clkinfo, sizeof clkinfo, req));
804 SYSCTL_PROC(_kern, KERN_CLOCKRATE, clockrate,
805 CTLTYPE_STRUCT|CTLFLAG_RD|CTLFLAG_MPSAFE,
806 0, 0, sysctl_kern_clockrate, "S,clockinfo",
807 "Rate and period of various kernel clocks");
812 watchdog_config(void *unused __unused, u_int cmd, int *error)
816 u = cmd & WD_INTERVAL;
817 if (u >= WD_TO_1SEC) {
818 watchdog_ticks = (1 << (u - WD_TO_1SEC)) * hz;
819 watchdog_enabled = 1;
822 watchdog_enabled = 0;
827 * Handle a watchdog timeout by dumping interrupt information and
828 * then either dropping to DDB or panicking.
841 nintr = eintrcnt - intrcnt;
843 printf("interrupt total\n");
844 while (--nintr >= 0) {
846 printf("%-12s %20lu\n", curname, *curintr);
847 curname += strlen(curname) + 1;
848 inttotal += *curintr++;
850 printf("Total %20ju\n", (uintmax_t)inttotal);
852 #if defined(KDB) && !defined(KDB_UNATTENDED)
854 kdb_enter(KDB_WHY_WATCHDOG, "watchdog timeout");
856 panic("watchdog timeout");
860 #endif /* SW_WATCHDOG */