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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 int slptime_threshold = 1800;
166 static int blktime_threshold = 900;
167 static int sleepfreq = 3;
175 int blkticks, slpticks, slptype, tryl, tticks;
179 blkticks = blktime_threshold * hz;
180 slpticks = slptime_threshold * hz;
183 * Avoid to sleep on the sx_lock in order to avoid a possible
184 * priority inversion problem leading to starvation.
185 * If the lock can't be held after 100 tries, panic.
187 if (!sx_try_slock(&allproc_lock)) {
189 panic("%s: possible deadlock detected on allproc_lock\n",
192 pause("allproc_lock deadlkres", sleepfreq * hz);
196 FOREACH_PROC_IN_SYSTEM(p) {
198 FOREACH_THREAD_IN_PROC(p, td) {
200 if (TD_ON_LOCK(td)) {
203 * The thread should be blocked on a
204 * turnstile, simply check if the
205 * turnstile channel is in good state.
207 MPASS(td->td_blocked != NULL);
208 tticks = ticks - td->td_blktick;
210 if (tticks > blkticks) {
213 * Accordingly with provided
214 * thresholds, this thread is
215 * stuck for too long on a
219 sx_sunlock(&allproc_lock);
220 panic("%s: possible deadlock detected for %p, blocked for %d ticks\n",
221 __func__, td, tticks);
223 } else if (TD_IS_SLEEPING(td)) {
226 * Check if the thread is sleeping on a
227 * lock, otherwise skip the check.
228 * Drop the thread lock in order to
229 * avoid a LOR with the sleepqueue
232 wchan = td->td_wchan;
233 tticks = ticks - td->td_slptick;
235 slptype = sleepq_type(wchan);
236 if ((slptype == SLEEPQ_SX ||
237 slptype == SLEEPQ_LK) &&
241 * Accordingly with provided
242 * thresholds, this thread is
243 * stuck for too long on a
247 sx_sunlock(&allproc_lock);
248 panic("%s: possible deadlock detected for %p, blocked for %d ticks\n",
249 __func__, td, tticks);
256 sx_sunlock(&allproc_lock);
258 /* Sleep for sleepfreq seconds. */
259 pause("deadlkres", sleepfreq * hz);
263 static struct kthread_desc deadlkres_kd = {
266 (struct thread **)NULL
269 SYSINIT(deadlkres, SI_SUB_CLOCKS, SI_ORDER_ANY, kthread_start, &deadlkres_kd);
271 SYSCTL_NODE(_debug, OID_AUTO, deadlkres, CTLFLAG_RW, 0, "Deadlock resolver");
272 SYSCTL_INT(_debug_deadlkres, OID_AUTO, slptime_threshold, CTLFLAG_RW,
273 &slptime_threshold, 0,
274 "Number of seconds within is valid to sleep on a sleepqueue");
275 SYSCTL_INT(_debug_deadlkres, OID_AUTO, blktime_threshold, CTLFLAG_RW,
276 &blktime_threshold, 0,
277 "Number of seconds within is valid to block on a turnstile");
278 SYSCTL_INT(_debug_deadlkres, OID_AUTO, sleepfreq, CTLFLAG_RW, &sleepfreq, 0,
279 "Number of seconds between any deadlock resolver thread run");
280 #endif /* DEADLKRES */
283 read_cpu_time(long *cp_time)
288 /* Sum up global cp_time[]. */
289 bzero(cp_time, sizeof(long) * CPUSTATES);
290 for (i = 0; i <= mp_maxid; i++) {
294 for (j = 0; j < CPUSTATES; j++)
295 cp_time[j] += pc->pc_cp_time[j];
300 #include <sys/watchdog.h>
302 static int watchdog_ticks;
303 static int watchdog_enabled;
304 static void watchdog_fire(void);
305 static void watchdog_config(void *, u_int, int *);
306 #endif /* SW_WATCHDOG */
309 * Clock handling routines.
311 * This code is written to operate with two timers that run independently of
314 * The main timer, running hz times per second, is used to trigger interval
315 * timers, timeouts and rescheduling as needed.
317 * The second timer handles kernel and user profiling,
318 * and does resource use estimation. If the second timer is programmable,
319 * it is randomized to avoid aliasing between the two clocks. For example,
320 * the randomization prevents an adversary from always giving up the cpu
321 * just before its quantum expires. Otherwise, it would never accumulate
322 * cpu ticks. The mean frequency of the second timer is stathz.
324 * If no second timer exists, stathz will be zero; in this case we drive
325 * profiling and statistics off the main clock. This WILL NOT be accurate;
326 * do not do it unless absolutely necessary.
328 * The statistics clock may (or may not) be run at a higher rate while
329 * profiling. This profile clock runs at profhz. We require that profhz
330 * be an integral multiple of stathz.
332 * If the statistics clock is running fast, it must be divided by the ratio
333 * profhz/stathz for statistics. (For profiling, every tick counts.)
335 * Time-of-day is maintained using a "timecounter", which may or may
336 * not be related to the hardware generating the above mentioned
347 * Initialize clock frequencies and start both clocks running.
357 * Set divisors to 1 (normal case) and let the machine-specific
360 mtx_init(&time_lock, "time lock", NULL, MTX_SPIN);
364 * Compute profhz/stathz, and fix profhz if needed.
366 i = stathz ? stathz : hz;
369 psratio = profhz / i;
371 EVENTHANDLER_REGISTER(watchdog_list, watchdog_config, NULL, 0);
376 * Each time the real-time timer fires, this function is called on all CPUs.
377 * Note that hardclock() calls hardclock_cpu() for the boot CPU, so only
378 * the other CPUs in the system need to call this function.
381 hardclock_cpu(int usermode)
383 struct pstats *pstats;
384 struct thread *td = curthread;
385 struct proc *p = td->td_proc;
389 * Run current process's virtual and profile time, as needed.
394 timevalisset(&pstats->p_timer[ITIMER_VIRTUAL].it_value)) {
396 if (itimerdecr(&pstats->p_timer[ITIMER_VIRTUAL], tick) == 0)
397 flags |= TDF_ALRMPEND | TDF_ASTPENDING;
400 if (timevalisset(&pstats->p_timer[ITIMER_PROF].it_value)) {
402 if (itimerdecr(&pstats->p_timer[ITIMER_PROF], tick) == 0)
403 flags |= TDF_PROFPEND | TDF_ASTPENDING;
408 td->td_flags |= flags;
412 if (PMC_CPU_HAS_SAMPLES(PCPU_GET(cpuid)))
413 PMC_CALL_HOOK_UNLOCKED(curthread, PMC_FN_DO_SAMPLES, NULL);
419 * The real-time timer, interrupting hz times per second.
422 hardclock(int usermode, uintfptr_t pc)
425 atomic_add_int((volatile int *)&ticks, 1);
426 hardclock_cpu(usermode);
429 * If no separate statistics clock is available, run it from here.
431 * XXX: this only works for UP
434 profclock(usermode, pc);
437 #ifdef DEVICE_POLLING
438 hardclock_device_poll(); /* this is very short and quick */
439 #endif /* DEVICE_POLLING */
441 if (watchdog_enabled > 0 && --watchdog_ticks <= 0)
443 #endif /* SW_WATCHDOG */
447 * Compute number of ticks in the specified amount of time.
453 register unsigned long ticks;
454 register long sec, usec;
457 * If the number of usecs in the whole seconds part of the time
458 * difference fits in a long, then the total number of usecs will
459 * fit in an unsigned long. Compute the total and convert it to
460 * ticks, rounding up and adding 1 to allow for the current tick
461 * to expire. Rounding also depends on unsigned long arithmetic
464 * Otherwise, if the number of ticks in the whole seconds part of
465 * the time difference fits in a long, then convert the parts to
466 * ticks separately and add, using similar rounding methods and
467 * overflow avoidance. This method would work in the previous
468 * case but it is slightly slower and assumes that hz is integral.
470 * Otherwise, round the time difference down to the maximum
471 * representable value.
473 * If ints have 32 bits, then the maximum value for any timeout in
474 * 10ms ticks is 248 days.
488 printf("tvotohz: negative time difference %ld sec %ld usec\n",
492 } else if (sec <= LONG_MAX / 1000000)
493 ticks = (sec * 1000000 + (unsigned long)usec + (tick - 1))
495 else if (sec <= LONG_MAX / hz)
497 + ((unsigned long)usec + (tick - 1)) / tick + 1;
506 * Start profiling on a process.
508 * Kernel profiling passes proc0 which never exits and hence
509 * keeps the profile clock running constantly.
513 register struct proc *p;
516 PROC_LOCK_ASSERT(p, MA_OWNED);
517 if (p->p_flag & P_STOPPROF)
519 if ((p->p_flag & P_PROFIL) == 0) {
520 p->p_flag |= P_PROFIL;
521 mtx_lock_spin(&time_lock);
522 if (++profprocs == 1)
523 cpu_startprofclock();
524 mtx_unlock_spin(&time_lock);
529 * Stop profiling on a process.
533 register struct proc *p;
536 PROC_LOCK_ASSERT(p, MA_OWNED);
537 if (p->p_flag & P_PROFIL) {
538 if (p->p_profthreads != 0) {
539 p->p_flag |= P_STOPPROF;
540 while (p->p_profthreads != 0)
541 msleep(&p->p_profthreads, &p->p_mtx, PPAUSE,
543 p->p_flag &= ~P_STOPPROF;
545 if ((p->p_flag & P_PROFIL) == 0)
547 p->p_flag &= ~P_PROFIL;
548 mtx_lock_spin(&time_lock);
549 if (--profprocs == 0)
551 mtx_unlock_spin(&time_lock);
556 * Statistics clock. Updates rusage information and calls the scheduler
557 * to adjust priorities of the active thread.
559 * This should be called by all active processors.
562 statclock(int usermode)
574 cp_time = (long *)PCPU_PTR(cp_time);
577 * Charge the time as appropriate.
580 if (p->p_nice > NZERO)
586 * Came from kernel mode, so we were:
587 * - handling an interrupt,
588 * - doing syscall or trap work on behalf of the current
590 * - spinning in the idle loop.
591 * Whichever it is, charge the time as appropriate.
592 * Note that we charge interrupts to the current process,
593 * regardless of whether they are ``for'' that process,
594 * so that we know how much of its real time was spent
595 * in ``non-process'' (i.e., interrupt) work.
597 if ((td->td_pflags & TDP_ITHREAD) ||
598 td->td_intr_nesting_level >= 2) {
604 if (!TD_IS_IDLETHREAD(td))
611 /* Update resource usage integrals and maximums. */
612 MPASS(p->p_vmspace != NULL);
615 ru->ru_ixrss += pgtok(vm->vm_tsize);
616 ru->ru_idrss += pgtok(vm->vm_dsize);
617 ru->ru_isrss += pgtok(vm->vm_ssize);
618 rss = pgtok(vmspace_resident_count(vm));
619 if (ru->ru_maxrss < rss)
621 KTR_POINT2(KTR_SCHED, "thread", sched_tdname(td), "statclock",
622 "prio:%d", td->td_priority, "stathz:%d", (stathz)?stathz:hz);
623 thread_lock_flags(td, MTX_QUIET);
629 profclock(int usermode, uintfptr_t pc)
640 * Came from user mode; CPU was in user state.
641 * If this process is being profiled, record the tick.
642 * if there is no related user location yet, don't
643 * bother trying to count it.
645 if (td->td_proc->p_flag & P_PROFIL)
646 addupc_intr(td, pc, 1);
651 * Kernel statistics are just like addupc_intr, only easier.
654 if (g->state == GMON_PROF_ON && pc >= g->lowpc) {
656 if (i < g->textsize) {
665 * Return information about system clocks.
668 sysctl_kern_clockrate(SYSCTL_HANDLER_ARGS)
670 struct clockinfo clkinfo;
672 * Construct clockinfo structure.
674 bzero(&clkinfo, sizeof(clkinfo));
677 clkinfo.profhz = profhz;
678 clkinfo.stathz = stathz ? stathz : hz;
679 return (sysctl_handle_opaque(oidp, &clkinfo, sizeof clkinfo, req));
682 SYSCTL_PROC(_kern, KERN_CLOCKRATE, clockrate,
683 CTLTYPE_STRUCT|CTLFLAG_RD|CTLFLAG_MPSAFE,
684 0, 0, sysctl_kern_clockrate, "S,clockinfo",
685 "Rate and period of various kernel clocks");
690 watchdog_config(void *unused __unused, u_int cmd, int *error)
694 u = cmd & WD_INTERVAL;
695 if (u >= WD_TO_1SEC) {
696 watchdog_ticks = (1 << (u - WD_TO_1SEC)) * hz;
697 watchdog_enabled = 1;
700 watchdog_enabled = 0;
705 * Handle a watchdog timeout by dumping interrupt information and
706 * then either dropping to DDB or panicking.
719 nintr = eintrcnt - intrcnt;
721 printf("interrupt total\n");
722 while (--nintr >= 0) {
724 printf("%-12s %20lu\n", curname, *curintr);
725 curname += strlen(curname) + 1;
726 inttotal += *curintr++;
728 printf("Total %20ju\n", (uintmax_t)inttotal);
730 #if defined(KDB) && !defined(KDB_UNATTENDED)
732 kdb_enter(KDB_WHY_WATCHDOG, "watchdog timeout");
734 panic("watchdog timeout");
738 #endif /* SW_WATCHDOG */