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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>
53 #include <sys/mutex.h>
55 #include <sys/resource.h>
56 #include <sys/resourcevar.h>
57 #include <sys/sched.h>
58 #include <sys/signalvar.h>
62 #include <vm/vm_map.h>
63 #include <sys/sysctl.h>
65 #include <sys/interrupt.h>
66 #include <sys/limits.h>
67 #include <sys/timetc.h>
74 #include <sys/pmckern.h>
78 extern void hardclock_device_poll(void);
79 #endif /* DEVICE_POLLING */
81 static void initclocks(void *dummy);
82 SYSINIT(clocks, SI_SUB_CLOCKS, SI_ORDER_FIRST, initclocks, NULL)
84 /* Spin-lock protecting profiling statistics. */
85 static struct mtx time_lock;
88 sysctl_kern_cp_time(SYSCTL_HANDLER_ARGS)
91 long cp_time[CPUSTATES];
94 unsigned int cp_time32[CPUSTATES];
97 read_cpu_time(cp_time);
99 if (req->flags & SCTL_MASK32) {
101 return SYSCTL_OUT(req, 0, sizeof(cp_time32));
102 for (i = 0; i < CPUSTATES; i++)
103 cp_time32[i] = (unsigned int)cp_time[i];
104 error = SYSCTL_OUT(req, cp_time32, sizeof(cp_time32));
109 return SYSCTL_OUT(req, 0, sizeof(cp_time));
110 error = SYSCTL_OUT(req, cp_time, sizeof(cp_time));
115 SYSCTL_PROC(_kern, OID_AUTO, cp_time, CTLTYPE_LONG|CTLFLAG_RD,
116 0,0, sysctl_kern_cp_time, "LU", "CPU time statistics");
118 static long empty[CPUSTATES];
121 sysctl_kern_cp_times(SYSCTL_HANDLER_ARGS)
128 unsigned int cp_time32[CPUSTATES];
134 if (req->flags & SCTL_MASK32)
135 return SYSCTL_OUT(req, 0, sizeof(cp_time32) * (mp_maxid + 1));
138 return SYSCTL_OUT(req, 0, sizeof(long) * CPUSTATES * (mp_maxid + 1));
140 for (error = 0, c = 0; error == 0 && c <= mp_maxid; c++) {
141 if (!CPU_ABSENT(c)) {
143 cp_time = pcpu->pc_cp_time;
148 if (req->flags & SCTL_MASK32) {
149 for (i = 0; i < CPUSTATES; i++)
150 cp_time32[i] = (unsigned int)cp_time[i];
151 error = SYSCTL_OUT(req, cp_time32, sizeof(cp_time32));
154 error = SYSCTL_OUT(req, cp_time, sizeof(long) * CPUSTATES);
159 SYSCTL_PROC(_kern, OID_AUTO, cp_times, CTLTYPE_LONG|CTLFLAG_RD,
160 0,0, sysctl_kern_cp_times, "LU", "per-CPU time statistics");
163 read_cpu_time(long *cp_time)
168 /* Sum up global cp_time[]. */
169 bzero(cp_time, sizeof(long) * CPUSTATES);
170 for (i = 0; i <= mp_maxid; i++) {
174 for (j = 0; j < CPUSTATES; j++)
175 cp_time[j] += pc->pc_cp_time[j];
180 #include <sys/watchdog.h>
182 static int watchdog_ticks;
183 static int watchdog_enabled;
184 static void watchdog_fire(void);
185 static void watchdog_config(void *, u_int, int *);
186 #endif /* SW_WATCHDOG */
189 * Clock handling routines.
191 * This code is written to operate with two timers that run independently of
194 * The main timer, running hz times per second, is used to trigger interval
195 * timers, timeouts and rescheduling as needed.
197 * The second timer handles kernel and user profiling,
198 * and does resource use estimation. If the second timer is programmable,
199 * it is randomized to avoid aliasing between the two clocks. For example,
200 * the randomization prevents an adversary from always giving up the cpu
201 * just before its quantum expires. Otherwise, it would never accumulate
202 * cpu ticks. The mean frequency of the second timer is stathz.
204 * If no second timer exists, stathz will be zero; in this case we drive
205 * profiling and statistics off the main clock. This WILL NOT be accurate;
206 * do not do it unless absolutely necessary.
208 * The statistics clock may (or may not) be run at a higher rate while
209 * profiling. This profile clock runs at profhz. We require that profhz
210 * be an integral multiple of stathz.
212 * If the statistics clock is running fast, it must be divided by the ratio
213 * profhz/stathz for statistics. (For profiling, every tick counts.)
215 * Time-of-day is maintained using a "timecounter", which may or may
216 * not be related to the hardware generating the above mentioned
227 * Initialize clock frequencies and start both clocks running.
237 * Set divisors to 1 (normal case) and let the machine-specific
240 mtx_init(&time_lock, "time lock", NULL, MTX_SPIN);
244 * Compute profhz/stathz, and fix profhz if needed.
246 i = stathz ? stathz : hz;
249 psratio = profhz / i;
251 EVENTHANDLER_REGISTER(watchdog_list, watchdog_config, NULL, 0);
256 * Each time the real-time timer fires, this function is called on all CPUs.
257 * Note that hardclock() calls hardclock_cpu() for the boot CPU, so only
258 * the other CPUs in the system need to call this function.
261 hardclock_cpu(int usermode)
263 struct pstats *pstats;
264 struct thread *td = curthread;
265 struct proc *p = td->td_proc;
269 * Run current process's virtual and profile time, as needed.
274 timevalisset(&pstats->p_timer[ITIMER_VIRTUAL].it_value)) {
276 if (itimerdecr(&pstats->p_timer[ITIMER_VIRTUAL], tick) == 0)
277 flags |= TDF_ALRMPEND | TDF_ASTPENDING;
280 if (timevalisset(&pstats->p_timer[ITIMER_PROF].it_value)) {
282 if (itimerdecr(&pstats->p_timer[ITIMER_PROF], tick) == 0)
283 flags |= TDF_PROFPEND | TDF_ASTPENDING;
288 td->td_flags |= flags;
292 if (PMC_CPU_HAS_SAMPLES(PCPU_GET(cpuid)))
293 PMC_CALL_HOOK_UNLOCKED(curthread, PMC_FN_DO_SAMPLES, NULL);
298 * The real-time timer, interrupting hz times per second.
301 hardclock(int usermode, uintfptr_t pc)
303 int need_softclock = 0;
305 hardclock_cpu(usermode);
309 * If no separate statistics clock is available, run it from here.
311 * XXX: this only works for UP
314 profclock(usermode, pc);
318 #ifdef DEVICE_POLLING
319 hardclock_device_poll(); /* this is very short and quick */
320 #endif /* DEVICE_POLLING */
323 * Process callouts at a very low cpu priority, so we don't keep the
324 * relatively high clock interrupt priority any longer than necessary.
326 mtx_lock_spin_flags(&callout_lock, MTX_QUIET);
328 if (!TAILQ_EMPTY(&callwheel[ticks & callwheelmask])) {
330 } else if (softticks + 1 == ticks)
332 mtx_unlock_spin_flags(&callout_lock, MTX_QUIET);
335 * swi_sched acquires the thread lock, so we don't want to call it
336 * with callout_lock held; incorrect locking order.
339 swi_sched(softclock_ih, 0);
342 if (watchdog_enabled > 0 && --watchdog_ticks <= 0)
344 #endif /* SW_WATCHDOG */
348 * Compute number of ticks in the specified amount of time.
354 register unsigned long ticks;
355 register long sec, usec;
358 * If the number of usecs in the whole seconds part of the time
359 * difference fits in a long, then the total number of usecs will
360 * fit in an unsigned long. Compute the total and convert it to
361 * ticks, rounding up and adding 1 to allow for the current tick
362 * to expire. Rounding also depends on unsigned long arithmetic
365 * Otherwise, if the number of ticks in the whole seconds part of
366 * the time difference fits in a long, then convert the parts to
367 * ticks separately and add, using similar rounding methods and
368 * overflow avoidance. This method would work in the previous
369 * case but it is slightly slower and assumes that hz is integral.
371 * Otherwise, round the time difference down to the maximum
372 * representable value.
374 * If ints have 32 bits, then the maximum value for any timeout in
375 * 10ms ticks is 248 days.
389 printf("tvotohz: negative time difference %ld sec %ld usec\n",
393 } else if (sec <= LONG_MAX / 1000000)
394 ticks = (sec * 1000000 + (unsigned long)usec + (tick - 1))
396 else if (sec <= LONG_MAX / hz)
398 + ((unsigned long)usec + (tick - 1)) / tick + 1;
407 * Start profiling on a process.
409 * Kernel profiling passes proc0 which never exits and hence
410 * keeps the profile clock running constantly.
414 register struct proc *p;
417 PROC_LOCK_ASSERT(p, MA_OWNED);
418 if (p->p_flag & P_STOPPROF)
420 if ((p->p_flag & P_PROFIL) == 0) {
421 p->p_flag |= P_PROFIL;
422 mtx_lock_spin(&time_lock);
423 if (++profprocs == 1)
424 cpu_startprofclock();
425 mtx_unlock_spin(&time_lock);
430 * Stop profiling on a process.
434 register struct proc *p;
437 PROC_LOCK_ASSERT(p, MA_OWNED);
438 if (p->p_flag & P_PROFIL) {
439 if (p->p_profthreads != 0) {
440 p->p_flag |= P_STOPPROF;
441 while (p->p_profthreads != 0)
442 msleep(&p->p_profthreads, &p->p_mtx, PPAUSE,
444 p->p_flag &= ~P_STOPPROF;
446 if ((p->p_flag & P_PROFIL) == 0)
448 p->p_flag &= ~P_PROFIL;
449 mtx_lock_spin(&time_lock);
450 if (--profprocs == 0)
452 mtx_unlock_spin(&time_lock);
457 * Statistics clock. Updates rusage information and calls the scheduler
458 * to adjust priorities of the active thread.
460 * This should be called by all active processors.
463 statclock(int usermode)
475 cp_time = (long *)PCPU_PTR(cp_time);
478 * Charge the time as appropriate.
481 if (p->p_flag & P_SA)
485 if (p->p_nice > NZERO)
491 * Came from kernel mode, so we were:
492 * - handling an interrupt,
493 * - doing syscall or trap work on behalf of the current
495 * - spinning in the idle loop.
496 * Whichever it is, charge the time as appropriate.
497 * Note that we charge interrupts to the current process,
498 * regardless of whether they are ``for'' that process,
499 * so that we know how much of its real time was spent
500 * in ``non-process'' (i.e., interrupt) work.
502 if ((td->td_pflags & TDP_ITHREAD) ||
503 td->td_intr_nesting_level >= 2) {
508 if (p->p_flag & P_SA)
513 if (!TD_IS_IDLETHREAD(td))
520 /* Update resource usage integrals and maximums. */
521 MPASS(p->p_vmspace != NULL);
524 ru->ru_ixrss += pgtok(vm->vm_tsize);
525 ru->ru_idrss += pgtok(vm->vm_dsize);
526 ru->ru_isrss += pgtok(vm->vm_ssize);
527 rss = pgtok(vmspace_resident_count(vm));
528 if (ru->ru_maxrss < rss)
530 CTR4(KTR_SCHED, "statclock: %p(%s) prio %d stathz %d",
531 td, td->td_name, td->td_priority, (stathz)?stathz:hz);
532 thread_lock_flags(td, MTX_QUIET);
538 profclock(int usermode, uintfptr_t pc)
549 * Came from user mode; CPU was in user state.
550 * If this process is being profiled, record the tick.
551 * if there is no related user location yet, don't
552 * bother trying to count it.
554 if (td->td_proc->p_flag & P_PROFIL)
555 addupc_intr(td, pc, 1);
560 * Kernel statistics are just like addupc_intr, only easier.
563 if (g->state == GMON_PROF_ON && pc >= g->lowpc) {
565 if (i < g->textsize) {
574 * Return information about system clocks.
577 sysctl_kern_clockrate(SYSCTL_HANDLER_ARGS)
579 struct clockinfo clkinfo;
581 * Construct clockinfo structure.
583 bzero(&clkinfo, sizeof(clkinfo));
586 clkinfo.profhz = profhz;
587 clkinfo.stathz = stathz ? stathz : hz;
588 return (sysctl_handle_opaque(oidp, &clkinfo, sizeof clkinfo, req));
591 SYSCTL_PROC(_kern, KERN_CLOCKRATE, clockrate, CTLTYPE_STRUCT|CTLFLAG_RD,
592 0, 0, sysctl_kern_clockrate, "S,clockinfo",
593 "Rate and period of various kernel clocks");
598 watchdog_config(void *unused __unused, u_int cmd, int *error)
602 u = cmd & WD_INTERVAL;
603 if (u >= WD_TO_1SEC) {
604 watchdog_ticks = (1 << (u - WD_TO_1SEC)) * hz;
605 watchdog_enabled = 1;
608 watchdog_enabled = 0;
613 * Handle a watchdog timeout by dumping interrupt information and
614 * then either dropping to DDB or panicking.
627 nintr = eintrcnt - intrcnt;
629 printf("interrupt total\n");
630 while (--nintr >= 0) {
632 printf("%-12s %20lu\n", curname, *curintr);
633 curname += strlen(curname) + 1;
634 inttotal += *curintr++;
636 printf("Total %20ju\n", (uintmax_t)inttotal);
638 #if defined(KDB) && !defined(KDB_UNATTENDED)
640 kdb_enter(KDB_WHY_WATCHDOG, "watchdog timeout");
642 panic("watchdog timeout");
646 #endif /* SW_WATCHDOG */