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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"
43 #include "opt_kdtrace.h"
45 #include "opt_watchdog.h"
47 #include <sys/param.h>
48 #include <sys/systm.h>
49 #include <sys/callout.h>
51 #include <sys/kernel.h>
52 #include <sys/kthread.h>
55 #include <sys/mutex.h>
57 #include <sys/resource.h>
58 #include <sys/resourcevar.h>
59 #include <sys/sched.h>
61 #include <sys/signalvar.h>
62 #include <sys/sleepqueue.h>
66 #include <vm/vm_map.h>
67 #include <sys/sysctl.h>
69 #include <sys/interrupt.h>
70 #include <sys/limits.h>
71 #include <sys/timetc.h>
78 #include <sys/pmckern.h>
79 PMC_SOFT_DEFINE( , , clock, hard);
80 PMC_SOFT_DEFINE( , , clock, stat);
84 extern void hardclock_device_poll(void);
85 #endif /* DEVICE_POLLING */
87 static void initclocks(void *dummy);
88 SYSINIT(clocks, SI_SUB_CLOCKS, SI_ORDER_FIRST, initclocks, NULL);
90 /* Spin-lock protecting profiling statistics. */
91 static struct mtx time_lock;
93 SDT_PROVIDER_DECLARE(sched);
94 SDT_PROBE_DEFINE2(sched, , , tick, tick, "struct thread *", "struct proc *");
97 sysctl_kern_cp_time(SYSCTL_HANDLER_ARGS)
100 long cp_time[CPUSTATES];
103 unsigned int cp_time32[CPUSTATES];
106 read_cpu_time(cp_time);
108 if (req->flags & SCTL_MASK32) {
110 return SYSCTL_OUT(req, 0, sizeof(cp_time32));
111 for (i = 0; i < CPUSTATES; i++)
112 cp_time32[i] = (unsigned int)cp_time[i];
113 error = SYSCTL_OUT(req, cp_time32, sizeof(cp_time32));
118 return SYSCTL_OUT(req, 0, sizeof(cp_time));
119 error = SYSCTL_OUT(req, cp_time, sizeof(cp_time));
124 SYSCTL_PROC(_kern, OID_AUTO, cp_time, CTLTYPE_LONG|CTLFLAG_RD|CTLFLAG_MPSAFE,
125 0,0, sysctl_kern_cp_time, "LU", "CPU time statistics");
127 static long empty[CPUSTATES];
130 sysctl_kern_cp_times(SYSCTL_HANDLER_ARGS)
137 unsigned int cp_time32[CPUSTATES];
143 if (req->flags & SCTL_MASK32)
144 return SYSCTL_OUT(req, 0, sizeof(cp_time32) * (mp_maxid + 1));
147 return SYSCTL_OUT(req, 0, sizeof(long) * CPUSTATES * (mp_maxid + 1));
149 for (error = 0, c = 0; error == 0 && c <= mp_maxid; c++) {
150 if (!CPU_ABSENT(c)) {
152 cp_time = pcpu->pc_cp_time;
157 if (req->flags & SCTL_MASK32) {
158 for (i = 0; i < CPUSTATES; i++)
159 cp_time32[i] = (unsigned int)cp_time[i];
160 error = SYSCTL_OUT(req, cp_time32, sizeof(cp_time32));
163 error = SYSCTL_OUT(req, cp_time, sizeof(long) * CPUSTATES);
168 SYSCTL_PROC(_kern, OID_AUTO, cp_times, CTLTYPE_LONG|CTLFLAG_RD|CTLFLAG_MPSAFE,
169 0,0, sysctl_kern_cp_times, "LU", "per-CPU time statistics");
172 static const char *blessed[] = {
178 static int slptime_threshold = 1800;
179 static int blktime_threshold = 900;
180 static int sleepfreq = 3;
188 int blkticks, i, slpticks, slptype, tryl, tticks;
192 blkticks = blktime_threshold * hz;
193 slpticks = slptime_threshold * hz;
196 * Avoid to sleep on the sx_lock in order to avoid a possible
197 * priority inversion problem leading to starvation.
198 * If the lock can't be held after 100 tries, panic.
200 if (!sx_try_slock(&allproc_lock)) {
202 panic("%s: possible deadlock detected on allproc_lock\n",
205 pause("allproc", sleepfreq * hz);
209 FOREACH_PROC_IN_SYSTEM(p) {
211 if (p->p_state == PRS_NEW) {
215 FOREACH_THREAD_IN_PROC(p, td) {
218 * Once a thread is found in "interesting"
219 * state a possible ticks wrap-up needs to be
223 if (TD_ON_LOCK(td) && ticks < td->td_blktick) {
226 * The thread should be blocked on a
227 * turnstile, simply check if the
228 * turnstile channel is in good state.
230 MPASS(td->td_blocked != NULL);
232 tticks = ticks - td->td_blktick;
234 if (tticks > blkticks) {
237 * Accordingly with provided
238 * thresholds, this thread is
239 * stuck for too long on a
243 sx_sunlock(&allproc_lock);
244 panic("%s: possible deadlock detected for %p, blocked for %d ticks\n",
245 __func__, td, tticks);
247 } else if (TD_IS_SLEEPING(td) &&
249 ticks < td->td_blktick) {
252 * Check if the thread is sleeping on a
253 * lock, otherwise skip the check.
254 * Drop the thread lock in order to
255 * avoid a LOR with the sleepqueue
258 wchan = td->td_wchan;
259 tticks = ticks - td->td_slptick;
261 slptype = sleepq_type(wchan);
262 if ((slptype == SLEEPQ_SX ||
263 slptype == SLEEPQ_LK) &&
267 * Accordingly with provided
268 * thresholds, this thread is
269 * stuck for too long on a
271 * However, being on a
272 * sleepqueue, we might still
273 * check for the blessed
277 for (i = 0; blessed[i] != NULL;
279 if (!strcmp(blessed[i],
290 sx_sunlock(&allproc_lock);
291 panic("%s: possible deadlock detected for %p, blocked for %d ticks\n",
292 __func__, td, tticks);
299 sx_sunlock(&allproc_lock);
301 /* Sleep for sleepfreq seconds. */
302 pause("-", sleepfreq * hz);
306 static struct kthread_desc deadlkres_kd = {
309 (struct thread **)NULL
312 SYSINIT(deadlkres, SI_SUB_CLOCKS, SI_ORDER_ANY, kthread_start, &deadlkres_kd);
314 SYSCTL_NODE(_debug, OID_AUTO, deadlkres, CTLFLAG_RW, 0, "Deadlock resolver");
315 SYSCTL_INT(_debug_deadlkres, OID_AUTO, slptime_threshold, CTLFLAG_RW,
316 &slptime_threshold, 0,
317 "Number of seconds within is valid to sleep on a sleepqueue");
318 SYSCTL_INT(_debug_deadlkres, OID_AUTO, blktime_threshold, CTLFLAG_RW,
319 &blktime_threshold, 0,
320 "Number of seconds within is valid to block on a turnstile");
321 SYSCTL_INT(_debug_deadlkres, OID_AUTO, sleepfreq, CTLFLAG_RW, &sleepfreq, 0,
322 "Number of seconds between any deadlock resolver thread run");
323 #endif /* DEADLKRES */
326 read_cpu_time(long *cp_time)
331 /* Sum up global cp_time[]. */
332 bzero(cp_time, sizeof(long) * CPUSTATES);
335 for (j = 0; j < CPUSTATES; j++)
336 cp_time[j] += pc->pc_cp_time[j];
341 #include <sys/watchdog.h>
343 static int watchdog_ticks;
344 static int watchdog_enabled;
345 static void watchdog_fire(void);
346 static void watchdog_config(void *, u_int, int *);
347 #endif /* SW_WATCHDOG */
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 static DPCPU_DEFINE(int, pcputicks); /* Per-CPU version of ticks. */
388 static int global_hardclock_run = 0;
391 * Initialize clock frequencies and start both clocks running.
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);
420 * Each time the real-time timer fires, this function is called on all CPUs.
421 * Note that hardclock() calls hardclock_cpu() for the boot CPU, so only
422 * the other CPUs in the system need to call this function.
425 hardclock_cpu(int usermode)
427 struct pstats *pstats;
428 struct thread *td = curthread;
429 struct proc *p = td->td_proc;
433 * Run current process's virtual and profile time, as needed.
438 timevalisset(&pstats->p_timer[ITIMER_VIRTUAL].it_value)) {
440 if (itimerdecr(&pstats->p_timer[ITIMER_VIRTUAL], tick) == 0)
441 flags |= TDF_ALRMPEND | TDF_ASTPENDING;
444 if (timevalisset(&pstats->p_timer[ITIMER_PROF].it_value)) {
446 if (itimerdecr(&pstats->p_timer[ITIMER_PROF], tick) == 0)
447 flags |= TDF_PROFPEND | TDF_ASTPENDING;
452 td->td_flags |= flags;
456 if (PMC_CPU_HAS_SAMPLES(PCPU_GET(cpuid)))
457 PMC_CALL_HOOK_UNLOCKED(curthread, PMC_FN_DO_SAMPLES, NULL);
458 if (td->td_intr_frame != NULL)
459 PMC_SOFT_CALL_TF( , , clock, hard, td->td_intr_frame);
465 * The real-time timer, interrupting hz times per second.
468 hardclock(int usermode, uintfptr_t pc)
471 atomic_add_int((volatile int *)&ticks, 1);
472 hardclock_cpu(usermode);
474 cpu_tick_calibration();
476 * If no separate statistics clock is available, run it from here.
478 * XXX: this only works for UP
481 profclock(usermode, pc);
484 #ifdef DEVICE_POLLING
485 hardclock_device_poll(); /* this is very short and quick */
486 #endif /* DEVICE_POLLING */
488 if (watchdog_enabled > 0 && --watchdog_ticks <= 0)
490 #endif /* SW_WATCHDOG */
494 hardclock_cnt(int cnt, int usermode)
496 struct pstats *pstats;
497 struct thread *td = curthread;
498 struct proc *p = td->td_proc;
499 int *t = DPCPU_PTR(pcputicks);
500 int flags, global, newticks;
503 #endif /* SW_WATCHDOG */
506 * Update per-CPU and possibly global ticks values.
511 newticks = *t - global;
518 } while (!atomic_cmpset_int(&ticks, global, *t));
521 * Run current process's virtual and profile time, as needed.
526 timevalisset(&pstats->p_timer[ITIMER_VIRTUAL].it_value)) {
528 if (itimerdecr(&pstats->p_timer[ITIMER_VIRTUAL],
530 flags |= TDF_ALRMPEND | TDF_ASTPENDING;
533 if (timevalisset(&pstats->p_timer[ITIMER_PROF].it_value)) {
535 if (itimerdecr(&pstats->p_timer[ITIMER_PROF],
537 flags |= TDF_PROFPEND | TDF_ASTPENDING;
542 td->td_flags |= flags;
546 if (PMC_CPU_HAS_SAMPLES(PCPU_GET(cpuid)))
547 PMC_CALL_HOOK_UNLOCKED(curthread, PMC_FN_DO_SAMPLES, NULL);
548 if (td->td_intr_frame != NULL)
549 PMC_SOFT_CALL_TF( , , clock, hard, td->td_intr_frame);
552 /* We are in charge to handle this tick duty. */
554 /* Dangerous and no need to call these things concurrently. */
555 if (atomic_cmpset_acq_int(&global_hardclock_run, 0, 1)) {
556 tc_ticktock(newticks);
557 #ifdef DEVICE_POLLING
558 /* This is very short and quick. */
559 hardclock_device_poll();
560 #endif /* DEVICE_POLLING */
561 atomic_store_rel_int(&global_hardclock_run, 0);
564 if (watchdog_enabled > 0) {
565 i = atomic_fetchadd_int(&watchdog_ticks, -newticks);
566 if (i > 0 && i <= newticks)
569 #endif /* SW_WATCHDOG */
571 if (curcpu == CPU_FIRST())
572 cpu_tick_calibration();
576 hardclock_sync(int cpu)
578 int *t = DPCPU_ID_PTR(cpu, pcputicks);
584 * Compute number of ticks in the specified amount of time.
590 register unsigned long ticks;
591 register long sec, usec;
594 * If the number of usecs in the whole seconds part of the time
595 * difference fits in a long, then the total number of usecs will
596 * fit in an unsigned long. Compute the total and convert it to
597 * ticks, rounding up and adding 1 to allow for the current tick
598 * to expire. Rounding also depends on unsigned long arithmetic
601 * Otherwise, if the number of ticks in the whole seconds part of
602 * the time difference fits in a long, then convert the parts to
603 * ticks separately and add, using similar rounding methods and
604 * overflow avoidance. This method would work in the previous
605 * case but it is slightly slower and assumes that hz is integral.
607 * Otherwise, round the time difference down to the maximum
608 * representable value.
610 * If ints have 32 bits, then the maximum value for any timeout in
611 * 10ms ticks is 248 days.
625 printf("tvotohz: negative time difference %ld sec %ld usec\n",
629 } else if (sec <= LONG_MAX / 1000000)
630 ticks = (sec * 1000000 + (unsigned long)usec + (tick - 1))
632 else if (sec <= LONG_MAX / hz)
634 + ((unsigned long)usec + (tick - 1)) / tick + 1;
643 * Start profiling on a process.
645 * Kernel profiling passes proc0 which never exits and hence
646 * keeps the profile clock running constantly.
650 register struct proc *p;
653 PROC_LOCK_ASSERT(p, MA_OWNED);
654 if (p->p_flag & P_STOPPROF)
656 if ((p->p_flag & P_PROFIL) == 0) {
657 p->p_flag |= P_PROFIL;
658 mtx_lock(&time_lock);
659 if (++profprocs == 1)
660 cpu_startprofclock();
661 mtx_unlock(&time_lock);
666 * Stop profiling on a process.
670 register struct proc *p;
673 PROC_LOCK_ASSERT(p, MA_OWNED);
674 if (p->p_flag & P_PROFIL) {
675 if (p->p_profthreads != 0) {
676 p->p_flag |= P_STOPPROF;
677 while (p->p_profthreads != 0)
678 msleep(&p->p_profthreads, &p->p_mtx, PPAUSE,
680 p->p_flag &= ~P_STOPPROF;
682 if ((p->p_flag & P_PROFIL) == 0)
684 p->p_flag &= ~P_PROFIL;
685 mtx_lock(&time_lock);
686 if (--profprocs == 0)
688 mtx_unlock(&time_lock);
693 * Statistics clock. Updates rusage information and calls the scheduler
694 * to adjust priorities of the active thread.
696 * This should be called by all active processors.
699 statclock(int usermode)
702 statclock_cnt(1, usermode);
706 statclock_cnt(int cnt, int usermode)
718 cp_time = (long *)PCPU_PTR(cp_time);
721 * Charge the time as appropriate.
723 td->td_uticks += cnt;
724 if (p->p_nice > NZERO)
725 cp_time[CP_NICE] += cnt;
727 cp_time[CP_USER] += cnt;
730 * Came from kernel mode, so we were:
731 * - handling an interrupt,
732 * - doing syscall or trap work on behalf of the current
734 * - spinning in the idle loop.
735 * Whichever it is, charge the time as appropriate.
736 * Note that we charge interrupts to the current process,
737 * regardless of whether they are ``for'' that process,
738 * so that we know how much of its real time was spent
739 * in ``non-process'' (i.e., interrupt) work.
741 if ((td->td_pflags & TDP_ITHREAD) ||
742 td->td_intr_nesting_level >= 2) {
743 td->td_iticks += cnt;
744 cp_time[CP_INTR] += cnt;
746 td->td_pticks += cnt;
747 td->td_sticks += cnt;
748 if (!TD_IS_IDLETHREAD(td))
749 cp_time[CP_SYS] += cnt;
751 cp_time[CP_IDLE] += cnt;
755 /* Update resource usage integrals and maximums. */
756 MPASS(p->p_vmspace != NULL);
759 ru->ru_ixrss += pgtok(vm->vm_tsize) * cnt;
760 ru->ru_idrss += pgtok(vm->vm_dsize) * cnt;
761 ru->ru_isrss += pgtok(vm->vm_ssize) * cnt;
762 rss = pgtok(vmspace_resident_count(vm));
763 if (ru->ru_maxrss < rss)
765 KTR_POINT2(KTR_SCHED, "thread", sched_tdname(td), "statclock",
766 "prio:%d", td->td_priority, "stathz:%d", (stathz)?stathz:hz);
767 SDT_PROBE2(sched, , , tick, td, td->td_proc);
768 thread_lock_flags(td, MTX_QUIET);
769 for ( ; cnt > 0; cnt--)
773 if (td->td_intr_frame != NULL)
774 PMC_SOFT_CALL_TF( , , clock, stat, td->td_intr_frame);
779 profclock(int usermode, uintfptr_t pc)
782 profclock_cnt(1, usermode, pc);
786 profclock_cnt(int cnt, int usermode, uintfptr_t pc)
797 * Came from user mode; CPU was in user state.
798 * If this process is being profiled, record the tick.
799 * if there is no related user location yet, don't
800 * bother trying to count it.
802 if (td->td_proc->p_flag & P_PROFIL)
803 addupc_intr(td, pc, cnt);
808 * Kernel statistics are just like addupc_intr, only easier.
811 if (g->state == GMON_PROF_ON && pc >= g->lowpc) {
813 if (i < g->textsize) {
822 * Return information about system clocks.
825 sysctl_kern_clockrate(SYSCTL_HANDLER_ARGS)
827 struct clockinfo clkinfo;
829 * Construct clockinfo structure.
831 bzero(&clkinfo, sizeof(clkinfo));
834 clkinfo.profhz = profhz;
835 clkinfo.stathz = stathz ? stathz : hz;
836 return (sysctl_handle_opaque(oidp, &clkinfo, sizeof clkinfo, req));
839 SYSCTL_PROC(_kern, KERN_CLOCKRATE, clockrate,
840 CTLTYPE_STRUCT|CTLFLAG_RD|CTLFLAG_MPSAFE,
841 0, 0, sysctl_kern_clockrate, "S,clockinfo",
842 "Rate and period of various kernel clocks");
847 watchdog_config(void *unused __unused, u_int cmd, int *error)
851 u = cmd & WD_INTERVAL;
852 if (u >= WD_TO_1SEC) {
853 watchdog_ticks = (1 << (u - WD_TO_1SEC)) * hz;
854 watchdog_enabled = 1;
857 watchdog_enabled = 0;
862 * Handle a watchdog timeout by dumping interrupt information and
863 * then either dropping to DDB or panicking.
876 nintr = sintrcnt / sizeof(u_long);
878 printf("interrupt total\n");
879 while (--nintr >= 0) {
881 printf("%-12s %20lu\n", curname, *curintr);
882 curname += strlen(curname) + 1;
883 inttotal += *curintr++;
885 printf("Total %20ju\n", (uintmax_t)inttotal);
887 #if defined(KDB) && !defined(KDB_UNATTENDED)
889 kdb_enter(KDB_WHY_WATCHDOG, "watchdog timeout");
891 panic("watchdog timeout");
895 #endif /* SW_WATCHDOG */