xref: /freebsd/sys/kern/kern_clock.c (revision 884a2a699669ec61e2366e3e358342dbc94be24a)
1 /*-
2  * Copyright (c) 1982, 1986, 1991, 1993
3  *	The Regents of the University of California.  All rights reserved.
4  * (c) UNIX System Laboratories, Inc.
5  * All or some portions of this file are derived from material licensed
6  * to the University of California by American Telephone and Telegraph
7  * Co. or Unix System Laboratories, Inc. and are reproduced herein with
8  * the permission of UNIX System Laboratories, Inc.
9  *
10  * Redistribution and use in source and binary forms, with or without
11  * modification, are permitted provided that the following conditions
12  * are met:
13  * 1. Redistributions of source code must retain the above copyright
14  *    notice, this list of conditions and the following disclaimer.
15  * 2. Redistributions in binary form must reproduce the above copyright
16  *    notice, this list of conditions and the following disclaimer in the
17  *    documentation and/or other materials provided with the distribution.
18  * 4. Neither the name of the University nor the names of its contributors
19  *    may be used to endorse or promote products derived from this software
20  *    without specific prior written permission.
21  *
22  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
23  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
24  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
25  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
26  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
27  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
28  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
29  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
30  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
31  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
32  * SUCH DAMAGE.
33  *
34  *	@(#)kern_clock.c	8.5 (Berkeley) 1/21/94
35  */
36 
37 #include <sys/cdefs.h>
38 __FBSDID("$FreeBSD$");
39 
40 #include "opt_kdb.h"
41 #include "opt_device_polling.h"
42 #include "opt_hwpmc_hooks.h"
43 #include "opt_ntp.h"
44 #include "opt_watchdog.h"
45 
46 #include <sys/param.h>
47 #include <sys/systm.h>
48 #include <sys/callout.h>
49 #include <sys/kdb.h>
50 #include <sys/kernel.h>
51 #include <sys/kthread.h>
52 #include <sys/ktr.h>
53 #include <sys/lock.h>
54 #include <sys/mutex.h>
55 #include <sys/proc.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>
61 #include <sys/smp.h>
62 #include <vm/vm.h>
63 #include <vm/pmap.h>
64 #include <vm/vm_map.h>
65 #include <sys/sysctl.h>
66 #include <sys/bus.h>
67 #include <sys/interrupt.h>
68 #include <sys/limits.h>
69 #include <sys/timetc.h>
70 
71 #ifdef GPROF
72 #include <sys/gmon.h>
73 #endif
74 
75 #ifdef HWPMC_HOOKS
76 #include <sys/pmckern.h>
77 #endif
78 
79 #ifdef DEVICE_POLLING
80 extern void hardclock_device_poll(void);
81 #endif /* DEVICE_POLLING */
82 
83 static void initclocks(void *dummy);
84 SYSINIT(clocks, SI_SUB_CLOCKS, SI_ORDER_FIRST, initclocks, NULL);
85 
86 /* Spin-lock protecting profiling statistics. */
87 static struct mtx time_lock;
88 
89 static int
90 sysctl_kern_cp_time(SYSCTL_HANDLER_ARGS)
91 {
92 	int error;
93 	long cp_time[CPUSTATES];
94 #ifdef SCTL_MASK32
95 	int i;
96 	unsigned int cp_time32[CPUSTATES];
97 #endif
98 
99 	read_cpu_time(cp_time);
100 #ifdef SCTL_MASK32
101 	if (req->flags & SCTL_MASK32) {
102 		if (!req->oldptr)
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));
107 	} else
108 #endif
109 	{
110 		if (!req->oldptr)
111 			return SYSCTL_OUT(req, 0, sizeof(cp_time));
112 		error = SYSCTL_OUT(req, cp_time, sizeof(cp_time));
113 	}
114 	return error;
115 }
116 
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");
119 
120 static long empty[CPUSTATES];
121 
122 static int
123 sysctl_kern_cp_times(SYSCTL_HANDLER_ARGS)
124 {
125 	struct pcpu *pcpu;
126 	int error;
127 	int c;
128 	long *cp_time;
129 #ifdef SCTL_MASK32
130 	unsigned int cp_time32[CPUSTATES];
131 	int i;
132 #endif
133 
134 	if (!req->oldptr) {
135 #ifdef SCTL_MASK32
136 		if (req->flags & SCTL_MASK32)
137 			return SYSCTL_OUT(req, 0, sizeof(cp_time32) * (mp_maxid + 1));
138 		else
139 #endif
140 			return SYSCTL_OUT(req, 0, sizeof(long) * CPUSTATES * (mp_maxid + 1));
141 	}
142 	for (error = 0, c = 0; error == 0 && c <= mp_maxid; c++) {
143 		if (!CPU_ABSENT(c)) {
144 			pcpu = pcpu_find(c);
145 			cp_time = pcpu->pc_cp_time;
146 		} else {
147 			cp_time = empty;
148 		}
149 #ifdef SCTL_MASK32
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));
154 		} else
155 #endif
156 			error = SYSCTL_OUT(req, cp_time, sizeof(long) * CPUSTATES);
157 	}
158 	return error;
159 }
160 
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");
163 
164 #ifdef DEADLKRES
165 static const char *blessed[] = {
166 	"getblk",
167 	"so_snd_sx",
168 	"so_rcv_sx",
169 	NULL
170 };
171 static int slptime_threshold = 1800;
172 static int blktime_threshold = 900;
173 static int sleepfreq = 3;
174 
175 static void
176 deadlkres(void)
177 {
178 	struct proc *p;
179 	struct thread *td;
180 	void *wchan;
181 	int blkticks, i, slpticks, slptype, tryl, tticks;
182 
183 	tryl = 0;
184 	for (;;) {
185 		blkticks = blktime_threshold * hz;
186 		slpticks = slptime_threshold * hz;
187 
188 		/*
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.
192 		 */
193 		if (!sx_try_slock(&allproc_lock)) {
194 			if (tryl > 100)
195 		panic("%s: possible deadlock detected on allproc_lock\n",
196 				    __func__);
197 			tryl++;
198 			pause("allproc", sleepfreq * hz);
199 			continue;
200 		}
201 		tryl = 0;
202 		FOREACH_PROC_IN_SYSTEM(p) {
203 			PROC_LOCK(p);
204 			if (p->p_state == PRS_NEW) {
205 				PROC_UNLOCK(p);
206 				continue;
207 			}
208 			FOREACH_THREAD_IN_PROC(p, td) {
209 
210 				/*
211 				 * Once a thread is found in "interesting"
212 				 * state a possible ticks wrap-up needs to be
213 				 * checked.
214 				 */
215 				thread_lock(td);
216 				if (TD_ON_LOCK(td) && ticks < td->td_blktick) {
217 
218 					/*
219 					 * The thread should be blocked on a
220 					 * turnstile, simply check if the
221 					 * turnstile channel is in good state.
222 					 */
223 					MPASS(td->td_blocked != NULL);
224 
225 					tticks = ticks - td->td_blktick;
226 					thread_unlock(td);
227 					if (tticks > blkticks) {
228 
229 						/*
230 						 * Accordingly with provided
231 						 * thresholds, this thread is
232 						 * stuck for too long on a
233 						 * turnstile.
234 						 */
235 						PROC_UNLOCK(p);
236 						sx_sunlock(&allproc_lock);
237 	panic("%s: possible deadlock detected for %p, blocked for %d ticks\n",
238 						    __func__, td, tticks);
239 					}
240 				} else if (TD_IS_SLEEPING(td) &&
241 				    TD_ON_SLEEPQ(td) &&
242 				    ticks < td->td_blktick) {
243 
244 					/*
245 					 * Check if the thread is sleeping on a
246 					 * lock, otherwise skip the check.
247 					 * Drop the thread lock in order to
248 					 * avoid a LOR with the sleepqueue
249 					 * spinlock.
250 					 */
251 					wchan = td->td_wchan;
252 					tticks = ticks - td->td_slptick;
253 					thread_unlock(td);
254 					slptype = sleepq_type(wchan);
255 					if ((slptype == SLEEPQ_SX ||
256 					    slptype == SLEEPQ_LK) &&
257 					    tticks > slpticks) {
258 
259 						/*
260 						 * Accordingly with provided
261 						 * thresholds, this thread is
262 						 * stuck for too long on a
263 						 * sleepqueue.
264 						 * However, being on a
265 						 * sleepqueue, we might still
266 						 * check for the blessed
267 						 * list.
268 						 */
269 						tryl = 0;
270 						for (i = 0; blessed[i] != NULL;
271 						    i++) {
272 							if (!strcmp(blessed[i],
273 							    td->td_wmesg)) {
274 								tryl = 1;
275 								break;
276 							}
277 						}
278 						if (tryl != 0) {
279 							tryl = 0;
280 							continue;
281 						}
282 						PROC_UNLOCK(p);
283 						sx_sunlock(&allproc_lock);
284 	panic("%s: possible deadlock detected for %p, blocked for %d ticks\n",
285 						    __func__, td, tticks);
286 					}
287 				} else
288 					thread_unlock(td);
289 			}
290 			PROC_UNLOCK(p);
291 		}
292 		sx_sunlock(&allproc_lock);
293 
294 		/* Sleep for sleepfreq seconds. */
295 		pause("-", sleepfreq * hz);
296 	}
297 }
298 
299 static struct kthread_desc deadlkres_kd = {
300 	"deadlkres",
301 	deadlkres,
302 	(struct thread **)NULL
303 };
304 
305 SYSINIT(deadlkres, SI_SUB_CLOCKS, SI_ORDER_ANY, kthread_start, &deadlkres_kd);
306 
307 SYSCTL_NODE(_debug, OID_AUTO, deadlkres, CTLFLAG_RW, 0, "Deadlock resolver");
308 SYSCTL_INT(_debug_deadlkres, OID_AUTO, slptime_threshold, CTLFLAG_RW,
309     &slptime_threshold, 0,
310     "Number of seconds within is valid to sleep on a sleepqueue");
311 SYSCTL_INT(_debug_deadlkres, OID_AUTO, blktime_threshold, CTLFLAG_RW,
312     &blktime_threshold, 0,
313     "Number of seconds within is valid to block on a turnstile");
314 SYSCTL_INT(_debug_deadlkres, OID_AUTO, sleepfreq, CTLFLAG_RW, &sleepfreq, 0,
315     "Number of seconds between any deadlock resolver thread run");
316 #endif	/* DEADLKRES */
317 
318 void
319 read_cpu_time(long *cp_time)
320 {
321 	struct pcpu *pc;
322 	int i, j;
323 
324 	/* Sum up global cp_time[]. */
325 	bzero(cp_time, sizeof(long) * CPUSTATES);
326 	CPU_FOREACH(i) {
327 		pc = pcpu_find(i);
328 		for (j = 0; j < CPUSTATES; j++)
329 			cp_time[j] += pc->pc_cp_time[j];
330 	}
331 }
332 
333 #ifdef SW_WATCHDOG
334 #include <sys/watchdog.h>
335 
336 static int watchdog_ticks;
337 static int watchdog_enabled;
338 static void watchdog_fire(void);
339 static void watchdog_config(void *, u_int, int *);
340 #endif /* SW_WATCHDOG */
341 
342 /*
343  * Clock handling routines.
344  *
345  * This code is written to operate with two timers that run independently of
346  * each other.
347  *
348  * The main timer, running hz times per second, is used to trigger interval
349  * timers, timeouts and rescheduling as needed.
350  *
351  * The second timer handles kernel and user profiling,
352  * and does resource use estimation.  If the second timer is programmable,
353  * it is randomized to avoid aliasing between the two clocks.  For example,
354  * the randomization prevents an adversary from always giving up the cpu
355  * just before its quantum expires.  Otherwise, it would never accumulate
356  * cpu ticks.  The mean frequency of the second timer is stathz.
357  *
358  * If no second timer exists, stathz will be zero; in this case we drive
359  * profiling and statistics off the main clock.  This WILL NOT be accurate;
360  * do not do it unless absolutely necessary.
361  *
362  * The statistics clock may (or may not) be run at a higher rate while
363  * profiling.  This profile clock runs at profhz.  We require that profhz
364  * be an integral multiple of stathz.
365  *
366  * If the statistics clock is running fast, it must be divided by the ratio
367  * profhz/stathz for statistics.  (For profiling, every tick counts.)
368  *
369  * Time-of-day is maintained using a "timecounter", which may or may
370  * not be related to the hardware generating the above mentioned
371  * interrupts.
372  */
373 
374 int	stathz;
375 int	profhz;
376 int	profprocs;
377 int	ticks;
378 int	psratio;
379 
380 static DPCPU_DEFINE(int, pcputicks);	/* Per-CPU version of ticks. */
381 static int global_hardclock_run = 0;
382 
383 /*
384  * Initialize clock frequencies and start both clocks running.
385  */
386 /* ARGSUSED*/
387 static void
388 initclocks(dummy)
389 	void *dummy;
390 {
391 	register int i;
392 
393 	/*
394 	 * Set divisors to 1 (normal case) and let the machine-specific
395 	 * code do its bit.
396 	 */
397 	mtx_init(&time_lock, "time lock", NULL, MTX_DEF);
398 	cpu_initclocks();
399 
400 	/*
401 	 * Compute profhz/stathz, and fix profhz if needed.
402 	 */
403 	i = stathz ? stathz : hz;
404 	if (profhz == 0)
405 		profhz = i;
406 	psratio = profhz / i;
407 #ifdef SW_WATCHDOG
408 	EVENTHANDLER_REGISTER(watchdog_list, watchdog_config, NULL, 0);
409 #endif
410 }
411 
412 /*
413  * Each time the real-time timer fires, this function is called on all CPUs.
414  * Note that hardclock() calls hardclock_cpu() for the boot CPU, so only
415  * the other CPUs in the system need to call this function.
416  */
417 void
418 hardclock_cpu(int usermode)
419 {
420 	struct pstats *pstats;
421 	struct thread *td = curthread;
422 	struct proc *p = td->td_proc;
423 	int flags;
424 
425 	/*
426 	 * Run current process's virtual and profile time, as needed.
427 	 */
428 	pstats = p->p_stats;
429 	flags = 0;
430 	if (usermode &&
431 	    timevalisset(&pstats->p_timer[ITIMER_VIRTUAL].it_value)) {
432 		PROC_SLOCK(p);
433 		if (itimerdecr(&pstats->p_timer[ITIMER_VIRTUAL], tick) == 0)
434 			flags |= TDF_ALRMPEND | TDF_ASTPENDING;
435 		PROC_SUNLOCK(p);
436 	}
437 	if (timevalisset(&pstats->p_timer[ITIMER_PROF].it_value)) {
438 		PROC_SLOCK(p);
439 		if (itimerdecr(&pstats->p_timer[ITIMER_PROF], tick) == 0)
440 			flags |= TDF_PROFPEND | TDF_ASTPENDING;
441 		PROC_SUNLOCK(p);
442 	}
443 	thread_lock(td);
444 	sched_tick(1);
445 	td->td_flags |= flags;
446 	thread_unlock(td);
447 
448 #ifdef	HWPMC_HOOKS
449 	if (PMC_CPU_HAS_SAMPLES(PCPU_GET(cpuid)))
450 		PMC_CALL_HOOK_UNLOCKED(curthread, PMC_FN_DO_SAMPLES, NULL);
451 #endif
452 	callout_tick();
453 }
454 
455 /*
456  * The real-time timer, interrupting hz times per second.
457  */
458 void
459 hardclock(int usermode, uintfptr_t pc)
460 {
461 
462 	atomic_add_int((volatile int *)&ticks, 1);
463 	hardclock_cpu(usermode);
464 	tc_ticktock(1);
465 	cpu_tick_calibration();
466 	/*
467 	 * If no separate statistics clock is available, run it from here.
468 	 *
469 	 * XXX: this only works for UP
470 	 */
471 	if (stathz == 0) {
472 		profclock(usermode, pc);
473 		statclock(usermode);
474 	}
475 #ifdef DEVICE_POLLING
476 	hardclock_device_poll();	/* this is very short and quick */
477 #endif /* DEVICE_POLLING */
478 #ifdef SW_WATCHDOG
479 	if (watchdog_enabled > 0 && --watchdog_ticks <= 0)
480 		watchdog_fire();
481 #endif /* SW_WATCHDOG */
482 }
483 
484 void
485 hardclock_anycpu(int cnt, int usermode)
486 {
487 	struct pstats *pstats;
488 	struct thread *td = curthread;
489 	struct proc *p = td->td_proc;
490 	int *t = DPCPU_PTR(pcputicks);
491 	int flags, global, newticks;
492 #ifdef SW_WATCHDOG
493 	int i;
494 #endif /* SW_WATCHDOG */
495 
496 	/*
497 	 * Update per-CPU and possibly global ticks values.
498 	 */
499 	*t += cnt;
500 	do {
501 		global = ticks;
502 		newticks = *t - global;
503 		if (newticks <= 0) {
504 			if (newticks < -1)
505 				*t = global - 1;
506 			newticks = 0;
507 			break;
508 		}
509 	} while (!atomic_cmpset_int(&ticks, global, *t));
510 
511 	/*
512 	 * Run current process's virtual and profile time, as needed.
513 	 */
514 	pstats = p->p_stats;
515 	flags = 0;
516 	if (usermode &&
517 	    timevalisset(&pstats->p_timer[ITIMER_VIRTUAL].it_value)) {
518 		PROC_SLOCK(p);
519 		if (itimerdecr(&pstats->p_timer[ITIMER_VIRTUAL],
520 		    tick * cnt) == 0)
521 			flags |= TDF_ALRMPEND | TDF_ASTPENDING;
522 		PROC_SUNLOCK(p);
523 	}
524 	if (timevalisset(&pstats->p_timer[ITIMER_PROF].it_value)) {
525 		PROC_SLOCK(p);
526 		if (itimerdecr(&pstats->p_timer[ITIMER_PROF],
527 		    tick * cnt) == 0)
528 			flags |= TDF_PROFPEND | TDF_ASTPENDING;
529 		PROC_SUNLOCK(p);
530 	}
531 	thread_lock(td);
532 	sched_tick(cnt);
533 	td->td_flags |= flags;
534 	thread_unlock(td);
535 
536 #ifdef	HWPMC_HOOKS
537 	if (PMC_CPU_HAS_SAMPLES(PCPU_GET(cpuid)))
538 		PMC_CALL_HOOK_UNLOCKED(curthread, PMC_FN_DO_SAMPLES, NULL);
539 #endif
540 	callout_tick();
541 	/* We are in charge to handle this tick duty. */
542 	if (newticks > 0) {
543 		/* Dangerous and no need to call these things concurrently. */
544 		if (atomic_cmpset_acq_int(&global_hardclock_run, 0, 1)) {
545 			tc_ticktock(newticks);
546 #ifdef DEVICE_POLLING
547 			/* This is very short and quick. */
548 			hardclock_device_poll();
549 #endif /* DEVICE_POLLING */
550 			atomic_store_rel_int(&global_hardclock_run, 0);
551 		}
552 #ifdef SW_WATCHDOG
553 		if (watchdog_enabled > 0) {
554 			i = atomic_fetchadd_int(&watchdog_ticks, -newticks);
555 			if (i > 0 && i <= newticks)
556 				watchdog_fire();
557 		}
558 #endif /* SW_WATCHDOG */
559 	}
560 	if (curcpu == CPU_FIRST())
561 		cpu_tick_calibration();
562 }
563 
564 void
565 hardclock_sync(int cpu)
566 {
567 	int	*t = DPCPU_ID_PTR(cpu, pcputicks);
568 
569 	*t = ticks;
570 }
571 
572 /*
573  * Compute number of ticks in the specified amount of time.
574  */
575 int
576 tvtohz(tv)
577 	struct timeval *tv;
578 {
579 	register unsigned long ticks;
580 	register long sec, usec;
581 
582 	/*
583 	 * If the number of usecs in the whole seconds part of the time
584 	 * difference fits in a long, then the total number of usecs will
585 	 * fit in an unsigned long.  Compute the total and convert it to
586 	 * ticks, rounding up and adding 1 to allow for the current tick
587 	 * to expire.  Rounding also depends on unsigned long arithmetic
588 	 * to avoid overflow.
589 	 *
590 	 * Otherwise, if the number of ticks in the whole seconds part of
591 	 * the time difference fits in a long, then convert the parts to
592 	 * ticks separately and add, using similar rounding methods and
593 	 * overflow avoidance.  This method would work in the previous
594 	 * case but it is slightly slower and assumes that hz is integral.
595 	 *
596 	 * Otherwise, round the time difference down to the maximum
597 	 * representable value.
598 	 *
599 	 * If ints have 32 bits, then the maximum value for any timeout in
600 	 * 10ms ticks is 248 days.
601 	 */
602 	sec = tv->tv_sec;
603 	usec = tv->tv_usec;
604 	if (usec < 0) {
605 		sec--;
606 		usec += 1000000;
607 	}
608 	if (sec < 0) {
609 #ifdef DIAGNOSTIC
610 		if (usec > 0) {
611 			sec++;
612 			usec -= 1000000;
613 		}
614 		printf("tvotohz: negative time difference %ld sec %ld usec\n",
615 		       sec, usec);
616 #endif
617 		ticks = 1;
618 	} else if (sec <= LONG_MAX / 1000000)
619 		ticks = (sec * 1000000 + (unsigned long)usec + (tick - 1))
620 			/ tick + 1;
621 	else if (sec <= LONG_MAX / hz)
622 		ticks = sec * hz
623 			+ ((unsigned long)usec + (tick - 1)) / tick + 1;
624 	else
625 		ticks = LONG_MAX;
626 	if (ticks > INT_MAX)
627 		ticks = INT_MAX;
628 	return ((int)ticks);
629 }
630 
631 /*
632  * Start profiling on a process.
633  *
634  * Kernel profiling passes proc0 which never exits and hence
635  * keeps the profile clock running constantly.
636  */
637 void
638 startprofclock(p)
639 	register struct proc *p;
640 {
641 
642 	PROC_LOCK_ASSERT(p, MA_OWNED);
643 	if (p->p_flag & P_STOPPROF)
644 		return;
645 	if ((p->p_flag & P_PROFIL) == 0) {
646 		p->p_flag |= P_PROFIL;
647 		mtx_lock(&time_lock);
648 		if (++profprocs == 1)
649 			cpu_startprofclock();
650 		mtx_unlock(&time_lock);
651 	}
652 }
653 
654 /*
655  * Stop profiling on a process.
656  */
657 void
658 stopprofclock(p)
659 	register struct proc *p;
660 {
661 
662 	PROC_LOCK_ASSERT(p, MA_OWNED);
663 	if (p->p_flag & P_PROFIL) {
664 		if (p->p_profthreads != 0) {
665 			p->p_flag |= P_STOPPROF;
666 			while (p->p_profthreads != 0)
667 				msleep(&p->p_profthreads, &p->p_mtx, PPAUSE,
668 				    "stopprof", 0);
669 			p->p_flag &= ~P_STOPPROF;
670 		}
671 		if ((p->p_flag & P_PROFIL) == 0)
672 			return;
673 		p->p_flag &= ~P_PROFIL;
674 		mtx_lock(&time_lock);
675 		if (--profprocs == 0)
676 			cpu_stopprofclock();
677 		mtx_unlock(&time_lock);
678 	}
679 }
680 
681 /*
682  * Statistics clock.  Updates rusage information and calls the scheduler
683  * to adjust priorities of the active thread.
684  *
685  * This should be called by all active processors.
686  */
687 void
688 statclock(int usermode)
689 {
690 	struct rusage *ru;
691 	struct vmspace *vm;
692 	struct thread *td;
693 	struct proc *p;
694 	long rss;
695 	long *cp_time;
696 
697 	td = curthread;
698 	p = td->td_proc;
699 
700 	cp_time = (long *)PCPU_PTR(cp_time);
701 	if (usermode) {
702 		/*
703 		 * Charge the time as appropriate.
704 		 */
705 		td->td_uticks++;
706 		if (p->p_nice > NZERO)
707 			cp_time[CP_NICE]++;
708 		else
709 			cp_time[CP_USER]++;
710 	} else {
711 		/*
712 		 * Came from kernel mode, so we were:
713 		 * - handling an interrupt,
714 		 * - doing syscall or trap work on behalf of the current
715 		 *   user process, or
716 		 * - spinning in the idle loop.
717 		 * Whichever it is, charge the time as appropriate.
718 		 * Note that we charge interrupts to the current process,
719 		 * regardless of whether they are ``for'' that process,
720 		 * so that we know how much of its real time was spent
721 		 * in ``non-process'' (i.e., interrupt) work.
722 		 */
723 		if ((td->td_pflags & TDP_ITHREAD) ||
724 		    td->td_intr_nesting_level >= 2) {
725 			td->td_iticks++;
726 			cp_time[CP_INTR]++;
727 		} else {
728 			td->td_pticks++;
729 			td->td_sticks++;
730 			if (!TD_IS_IDLETHREAD(td))
731 				cp_time[CP_SYS]++;
732 			else
733 				cp_time[CP_IDLE]++;
734 		}
735 	}
736 
737 	/* Update resource usage integrals and maximums. */
738 	MPASS(p->p_vmspace != NULL);
739 	vm = p->p_vmspace;
740 	ru = &td->td_ru;
741 	ru->ru_ixrss += pgtok(vm->vm_tsize);
742 	ru->ru_idrss += pgtok(vm->vm_dsize);
743 	ru->ru_isrss += pgtok(vm->vm_ssize);
744 	rss = pgtok(vmspace_resident_count(vm));
745 	if (ru->ru_maxrss < rss)
746 		ru->ru_maxrss = rss;
747 	KTR_POINT2(KTR_SCHED, "thread", sched_tdname(td), "statclock",
748 	    "prio:%d", td->td_priority, "stathz:%d", (stathz)?stathz:hz);
749 	thread_lock_flags(td, MTX_QUIET);
750 	sched_clock(td);
751 	thread_unlock(td);
752 }
753 
754 void
755 profclock(int usermode, uintfptr_t pc)
756 {
757 	struct thread *td;
758 #ifdef GPROF
759 	struct gmonparam *g;
760 	uintfptr_t i;
761 #endif
762 
763 	td = curthread;
764 	if (usermode) {
765 		/*
766 		 * Came from user mode; CPU was in user state.
767 		 * If this process is being profiled, record the tick.
768 		 * if there is no related user location yet, don't
769 		 * bother trying to count it.
770 		 */
771 		if (td->td_proc->p_flag & P_PROFIL)
772 			addupc_intr(td, pc, 1);
773 	}
774 #ifdef GPROF
775 	else {
776 		/*
777 		 * Kernel statistics are just like addupc_intr, only easier.
778 		 */
779 		g = &_gmonparam;
780 		if (g->state == GMON_PROF_ON && pc >= g->lowpc) {
781 			i = PC_TO_I(g, pc);
782 			if (i < g->textsize) {
783 				KCOUNT(g, i)++;
784 			}
785 		}
786 	}
787 #endif
788 }
789 
790 /*
791  * Return information about system clocks.
792  */
793 static int
794 sysctl_kern_clockrate(SYSCTL_HANDLER_ARGS)
795 {
796 	struct clockinfo clkinfo;
797 	/*
798 	 * Construct clockinfo structure.
799 	 */
800 	bzero(&clkinfo, sizeof(clkinfo));
801 	clkinfo.hz = hz;
802 	clkinfo.tick = tick;
803 	clkinfo.profhz = profhz;
804 	clkinfo.stathz = stathz ? stathz : hz;
805 	return (sysctl_handle_opaque(oidp, &clkinfo, sizeof clkinfo, req));
806 }
807 
808 SYSCTL_PROC(_kern, KERN_CLOCKRATE, clockrate,
809 	CTLTYPE_STRUCT|CTLFLAG_RD|CTLFLAG_MPSAFE,
810 	0, 0, sysctl_kern_clockrate, "S,clockinfo",
811 	"Rate and period of various kernel clocks");
812 
813 #ifdef SW_WATCHDOG
814 
815 static void
816 watchdog_config(void *unused __unused, u_int cmd, int *error)
817 {
818 	u_int u;
819 
820 	u = cmd & WD_INTERVAL;
821 	if (u >= WD_TO_1SEC) {
822 		watchdog_ticks = (1 << (u - WD_TO_1SEC)) * hz;
823 		watchdog_enabled = 1;
824 		*error = 0;
825 	} else {
826 		watchdog_enabled = 0;
827 	}
828 }
829 
830 /*
831  * Handle a watchdog timeout by dumping interrupt information and
832  * then either dropping to DDB or panicking.
833  */
834 static void
835 watchdog_fire(void)
836 {
837 	int nintr;
838 	uint64_t inttotal;
839 	u_long *curintr;
840 	char *curname;
841 
842 	curintr = intrcnt;
843 	curname = intrnames;
844 	inttotal = 0;
845 	nintr = eintrcnt - intrcnt;
846 
847 	printf("interrupt                   total\n");
848 	while (--nintr >= 0) {
849 		if (*curintr)
850 			printf("%-12s %20lu\n", curname, *curintr);
851 		curname += strlen(curname) + 1;
852 		inttotal += *curintr++;
853 	}
854 	printf("Total        %20ju\n", (uintmax_t)inttotal);
855 
856 #if defined(KDB) && !defined(KDB_UNATTENDED)
857 	kdb_backtrace();
858 	kdb_enter(KDB_WHY_WATCHDOG, "watchdog timeout");
859 #else
860 	panic("watchdog timeout");
861 #endif
862 }
863 
864 #endif /* SW_WATCHDOG */
865