kern_clock.c

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/*-
 * Copyright (c) 1982, 1986, 1991, 1993
 *      The Regents of the University of California.  All rights reserved.
 * (c) UNIX System Laboratories, Inc.
 * All or some portions of this file are derived from material licensed
 * to the University of California by American Telephone and Telegraph
 * Co. or Unix System Laboratories, Inc. and are reproduced herein with
 * the permission of UNIX System Laboratories, Inc.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 *      @(#)kern_clock.c        8.5 (Berkeley) 1/21/94
 */

#include <sys/cdefs.h>
__FBSDID("$BSDSUniX$");

#include "opt_kdb.h"
#include "opt_device_polling.h"
#include "opt_hwpmc_hooks.h"
#include "opt_kdtrace.h"
#include "opt_ntp.h"
#include "opt_watchdog.h"

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/callout.h>
#include <sys/kdb.h>
#include <sys/kernel.h>
#include <sys/kthread.h>
#include <sys/ktr.h>
#include <sys/lock.h>
#include <sys/mutex.h>
#include <sys/proc.h>
#include <sys/resource.h>
#include <sys/resourcevar.h>
#include <sys/sched.h>
#include <sys/sdt.h>
#include <sys/signalvar.h>
#include <sys/sleepqueue.h>
#include <sys/smp.h>
#include <vm/vm.h>
#include <vm/pmap.h>
#include <vm/vm_map.h>
#include <sys/sysctl.h>
#include <sys/bus.h>
#include <sys/interrupt.h>
#include <sys/limits.h>
#include <sys/timetc.h>

#ifdef GPROF
#include <sys/gmon.h>
#endif

#ifdef HWPMC_HOOKS
#include <sys/pmckern.h>
PMC_SOFT_DEFINE( , , clock, hard);
PMC_SOFT_DEFINE( , , clock, stat);
PMC_SOFT_DEFINE_EX( , , clock, prof, \
    cpu_startprofclock, cpu_stopprofclock);
#endif

#ifdef DEVICE_POLLING
extern void hardclock_device_poll(void);
#endif /* DEVICE_POLLING */

static void initclocks(void *dummy);
SYSINIT(clocks, SI_SUB_CLOCKS, SI_ORDER_FIRST, initclocks, NULL);

/* Spin-lock protecting profiling statistics. */
static struct mtx time_lock;

SDT_PROVIDER_DECLARE(sched);
SDT_PROBE_DEFINE2(sched, , , tick, "struct thread *", "struct proc *");

static int
sysctl_kern_cp_time(SYSCTL_HANDLER_ARGS)
{
        int error;
        long cp_time[CPUSTATES];
#ifdef SCTL_MASK32
        int i;
        unsigned int cp_time32[CPUSTATES];
#endif

        read_cpu_time(cp_time);
#ifdef SCTL_MASK32
        if (req->flags & SCTL_MASK32) {
                if (!req->oldptr)
                        return SYSCTL_OUT(req, 0, sizeof(cp_time32));
                for (i = 0; i < CPUSTATES; i++)
                        cp_time32[i] = (unsigned int)cp_time[i];
                error = SYSCTL_OUT(req, cp_time32, sizeof(cp_time32));
        } else
#endif
        {
                if (!req->oldptr)
                        return SYSCTL_OUT(req, 0, sizeof(cp_time));
                error = SYSCTL_OUT(req, cp_time, sizeof(cp_time));
        }
        return error;
}

SYSCTL_PROC(_kern, OID_AUTO, cp_time, CTLTYPE_LONG|CTLFLAG_RD|CTLFLAG_MPSAFE,
    0,0, sysctl_kern_cp_time, "LU", "CPU time statistics");

static long empty[CPUSTATES];

static int
sysctl_kern_cp_times(SYSCTL_HANDLER_ARGS)
{
        struct pcpu *pcpu;
        int error;
        int c;
        long *cp_time;
#ifdef SCTL_MASK32
        unsigned int cp_time32[CPUSTATES];
        int i;
#endif

        if (!req->oldptr) {
#ifdef SCTL_MASK32
                if (req->flags & SCTL_MASK32)
                        return SYSCTL_OUT(req, 0, sizeof(cp_time32) * (mp_maxid + 1));
                else
#endif
                        return SYSCTL_OUT(req, 0, sizeof(long) * CPUSTATES * (mp_maxid + 1));
        }
        for (error = 0, c = 0; error == 0 && c <= mp_maxid; c++) {
                if (!CPU_ABSENT(c)) {
                        pcpu = pcpu_find(c);
                        cp_time = pcpu->pc_cp_time;
                } else {
                        cp_time = empty;
                }
#ifdef SCTL_MASK32
                if (req->flags & SCTL_MASK32) {
                        for (i = 0; i < CPUSTATES; i++)
                                cp_time32[i] = (unsigned int)cp_time[i];
                        error = SYSCTL_OUT(req, cp_time32, sizeof(cp_time32));
                } else
#endif
                        error = SYSCTL_OUT(req, cp_time, sizeof(long) * CPUSTATES);
        }
        return error;
}

SYSCTL_PROC(_kern, OID_AUTO, cp_times, CTLTYPE_LONG|CTLFLAG_RD|CTLFLAG_MPSAFE,
    0,0, sysctl_kern_cp_times, "LU", "per-CPU time statistics");

#ifdef DEADLKRES
static const char *blessed[] = {
        "getblk",
        "so_snd_sx",
        "so_rcv_sx",
        NULL
};
static int slptime_threshold = 1800;
static int blktime_threshold = 900;
static int sleepfreq = 3;

static void
deadlkres(void)
{
        struct proc *p;
        struct thread *td;
        void *wchan;
        int blkticks, i, slpticks, slptype, tryl, tticks;

        tryl = 0;
        for (;;) {
                blkticks = blktime_threshold * hz;
                slpticks = slptime_threshold * hz;

                /*
                 * Avoid to sleep on the sx_lock in order to avoid a possible
                 * priority inversion problem leading to starvation.
                 * If the lock can't be held after 100 tries, panic.
                 */
                if (!sx_try_slock(&allproc_lock)) {
                        if (tryl > 100)
                panic("%s: possible deadlock detected on allproc_lock\n",
                                    __func__);
                        tryl++;
                        pause("allproc", sleepfreq * hz);
                        continue;
                }
                tryl = 0;
                FOREACH_PROC_IN_SYSTEM(p) {
                        PROC_LOCK(p);
                        if (p->p_state == PRS_NEW) {
                                PROC_UNLOCK(p);
                                continue;
                        }
                        FOREACH_THREAD_IN_PROC(p, td) {

                                /*
                                 * Once a thread is found in "interesting"
                                 * state a possible ticks wrap-up needs to be
                                 * checked.
                                 */
                                thread_lock(td);
                                if (TD_ON_LOCK(td) && ticks < td->td_blktick) {

                                        /*
                                         * The thread should be blocked on a
                                         * turnstile, simply check if the
                                         * turnstile channel is in good state.
                                         */
                                        MPASS(td->td_blocked != NULL);

                                        tticks = ticks - td->td_blktick;
                                        thread_unlock(td);
                                        if (tticks > blkticks) {

                                                /*
                                                 * Accordingly with provided
                                                 * thresholds, this thread is
                                                 * stuck for too long on a
                                                 * turnstile.
                                                 */
                                                PROC_UNLOCK(p);
                                                sx_sunlock(&allproc_lock);
        panic("%s: possible deadlock detected for %p, blocked for %d ticks\n",
                                                    __func__, td, tticks);
                                        }
                                } else if (TD_IS_SLEEPING(td) &&
                                    TD_ON_SLEEPQ(td) &&
                                    ticks < td->td_blktick) {

                                        /*
                                         * Check if the thread is sleeping on a
                                         * lock, otherwise skip the check.
                                         * Drop the thread lock in order to
                                         * avoid a LOR with the sleepqueue
                                         * spinlock.
                                         */
                                        wchan = td->td_wchan;
                                        tticks = ticks - td->td_slptick;
                                        thread_unlock(td);
                                        slptype = sleepq_type(wchan);
                                        if ((slptype == SLEEPQ_SX ||
                                            slptype == SLEEPQ_LK) &&
                                            tticks > slpticks) {

                                                /*
                                                 * Accordingly with provided
                                                 * thresholds, this thread is
                                                 * stuck for too long on a
                                                 * sleepqueue.
                                                 * However, being on a
                                                 * sleepqueue, we might still
                                                 * check for the blessed
                                                 * list.
                                                 */
                                                tryl = 0;
                                                for (i = 0; blessed[i] != NULL;
                                                    i++) {
                                                        if (!strcmp(blessed[i],
                                                            td->td_wmesg)) {
                                                                tryl = 1;
                                                                break;
                                                        }
                                                }
                                                if (tryl != 0) {
                                                        tryl = 0;
                                                        continue;
                                                }
                                                PROC_UNLOCK(p);
                                                sx_sunlock(&allproc_lock);
        panic("%s: possible deadlock detected for %p, blocked for %d ticks\n",
                                                    __func__, td, tticks);
                                        }
                                } else
                                        thread_unlock(td);
                        }
                        PROC_UNLOCK(p);
                }
                sx_sunlock(&allproc_lock);

                /* Sleep for sleepfreq seconds. */
                pause("-", sleepfreq * hz);
        }
}

static struct kthread_desc deadlkres_kd = {
        "deadlkres",
        deadlkres,
        (struct thread **)NULL
};

SYSINIT(deadlkres, SI_SUB_CLOCKS, SI_ORDER_ANY, kthread_start, &deadlkres_kd);

static SYSCTL_NODE(_debug, OID_AUTO, deadlkres, CTLFLAG_RW, 0,
    "Deadlock resolver");
SYSCTL_INT(_debug_deadlkres, OID_AUTO, slptime_threshold, CTLFLAG_RW,
    &slptime_threshold, 0,
    "Number of seconds within is valid to sleep on a sleepqueue");
SYSCTL_INT(_debug_deadlkres, OID_AUTO, blktime_threshold, CTLFLAG_RW,
    &blktime_threshold, 0,
    "Number of seconds within is valid to block on a turnstile");
SYSCTL_INT(_debug_deadlkres, OID_AUTO, sleepfreq, CTLFLAG_RW, &sleepfreq, 0,
    "Number of seconds between any deadlock resolver thread run");
#endif  /* DEADLKRES */

void
read_cpu_time(long *cp_time)
{
        struct pcpu *pc;
        int i, j;

        /* Sum up global cp_time[]. */
        bzero(cp_time, sizeof(long) * CPUSTATES);
        CPU_FOREACH(i) {
                pc = pcpu_find(i);
                for (j = 0; j < CPUSTATES; j++)
                        cp_time[j] += pc->pc_cp_time[j];
        }
}

#ifdef SW_WATCHDOG
#include <sys/watchdog.h>

static int watchdog_ticks;
static int watchdog_enabled;
static void watchdog_fire(void);
static void watchdog_config(void *, u_int, int *);
#endif /* SW_WATCHDOG */

/*
 * Clock handling routines.
 *
 * This code is written to operate with two timers that run independently of
 * each other.
 *
 * The main timer, running hz times per second, is used to trigger interval
 * timers, timeouts and rescheduling as needed.
 *
 * The second timer handles kernel and user profiling,
 * and does resource use estimation.  If the second timer is programmable,
 * it is randomized to avoid aliasing between the two clocks.  For example,
 * the randomization prevents an adversary from always giving up the cpu
 * just before its quantum expires.  Otherwise, it would never accumulate
 * cpu ticks.  The mean frequency of the second timer is stathz.
 *
 * If no second timer exists, stathz will be zero; in this case we drive
 * profiling and statistics off the main clock.  This WILL NOT be accurate;
 * do not do it unless absolutely necessary.
 *
 * The statistics clock may (or may not) be run at a higher rate while
 * profiling.  This profile clock runs at profhz.  We require that profhz
 * be an integral multiple of stathz.
 *
 * If the statistics clock is running fast, it must be divided by the ratio
 * profhz/stathz for statistics.  (For profiling, every tick counts.)
 *
 * Time-of-day is maintained using a "timecounter", which may or may
 * not be related to the hardware generating the above mentioned
 * interrupts.
 */

int     stathz;
int     profhz;
int     profprocs;
volatile int    ticks;
int     psratio;

static DPCPU_DEFINE(int, pcputicks);    /* Per-CPU version of ticks. */
static int global_hardclock_run = 0;

/*
 * Initialize clock frequencies and start both clocks running.
 */
/* ARGSUSED*/
static void
initclocks(dummy)
        void *dummy;
{
        register int i;

        /*
         * Set divisors to 1 (normal case) and let the machine-specific
         * code do its bit.
         */
        mtx_init(&time_lock, "time lock", NULL, MTX_DEF);
        cpu_initclocks();

        /*
         * Compute profhz/stathz, and fix profhz if needed.
         */
        i = stathz ? stathz : hz;
        if (profhz == 0)
                profhz = i;
        psratio = profhz / i;
#ifdef SW_WATCHDOG
        EVENTHANDLER_REGISTER(watchdog_list, watchdog_config, NULL, 0);
#endif
}

/*
 * Each time the real-time timer fires, this function is called on all CPUs.
 * Note that hardclock() calls hardclock_cpu() for the boot CPU, so only
 * the other CPUs in the system need to call this function.
 */
void
hardclock_cpu(int usermode)
{
        struct pstats *pstats;
        struct thread *td = curthread;
        struct proc *p = td->td_proc;
        int flags;

        /*
         * Run current process's virtual and profile time, as needed.
         */
        pstats = p->p_stats;
        flags = 0;
        if (usermode &&
            timevalisset(&pstats->p_timer[ITIMER_VIRTUAL].it_value)) {
                PROC_SLOCK(p);
                if (itimerdecr(&pstats->p_timer[ITIMER_VIRTUAL], tick) == 0)
                        flags |= TDF_ALRMPEND | TDF_ASTPENDING;
                PROC_SUNLOCK(p);
        }
        if (timevalisset(&pstats->p_timer[ITIMER_PROF].it_value)) {
                PROC_SLOCK(p);
                if (itimerdecr(&pstats->p_timer[ITIMER_PROF], tick) == 0)
                        flags |= TDF_PROFPEND | TDF_ASTPENDING;
                PROC_SUNLOCK(p);
        }
        thread_lock(td);
        sched_tick(1);
        td->td_flags |= flags;
        thread_unlock(td);

#ifdef HWPMC_HOOKS
        if (PMC_CPU_HAS_SAMPLES(PCPU_GET(cpuid)))
                PMC_CALL_HOOK_UNLOCKED(curthread, PMC_FN_DO_SAMPLES, NULL);
        if (td->td_intr_frame != NULL)
                PMC_SOFT_CALL_TF( , , clock, hard, td->td_intr_frame);
#endif
        callout_tick();
}

/*
 * The real-time timer, interrupting hz times per second.
 */
void
hardclock(int usermode, uintfptr_t pc)
{

        atomic_add_int(&ticks, 1);
        hardclock_cpu(usermode);
        tc_ticktock(1);
        cpu_tick_calibration();
        /*
         * If no separate statistics clock is available, run it from here.
         *
         * XXX: this only works for UP
         */
        if (stathz == 0) {
                profclock(usermode, pc);
                statclock(usermode);
        }
#ifdef DEVICE_POLLING
        hardclock_device_poll();        /* this is very short and quick */
#endif /* DEVICE_POLLING */
#ifdef SW_WATCHDOG
        if (watchdog_enabled > 0 && --watchdog_ticks <= 0)
                watchdog_fire();
#endif /* SW_WATCHDOG */
}

void
hardclock_cnt(int cnt, int usermode)
{
        struct pstats *pstats;
        struct thread *td = curthread;
        struct proc *p = td->td_proc;
        int *t = DPCPU_PTR(pcputicks);
        int flags, global, newticks;
#ifdef SW_WATCHDOG
        int i;
#endif /* SW_WATCHDOG */

        /*
         * Update per-CPU and possibly global ticks values.
         */
        *t += cnt;
        do {
                global = ticks;
                newticks = *t - global;
                if (newticks <= 0) {
                        if (newticks < -1)
                                *t = global - 1;
                        newticks = 0;
                        break;
                }
        } while (!atomic_cmpset_int(&ticks, global, *t));

        /*
         * Run current process's virtual and profile time, as needed.
         */
        pstats = p->p_stats;
        flags = 0;
        if (usermode &&
            timevalisset(&pstats->p_timer[ITIMER_VIRTUAL].it_value)) {
                PROC_SLOCK(p);
                if (itimerdecr(&pstats->p_timer[ITIMER_VIRTUAL],
                    tick * cnt) == 0)
                        flags |= TDF_ALRMPEND | TDF_ASTPENDING;
                PROC_SUNLOCK(p);
        }
        if (timevalisset(&pstats->p_timer[ITIMER_PROF].it_value)) {
                PROC_SLOCK(p);
                if (itimerdecr(&pstats->p_timer[ITIMER_PROF],
                    tick * cnt) == 0)
                        flags |= TDF_PROFPEND | TDF_ASTPENDING;
                PROC_SUNLOCK(p);
        }
        thread_lock(td);
        sched_tick(cnt);
        td->td_flags |= flags;
        thread_unlock(td);

#ifdef  HWPMC_HOOKS
        if (PMC_CPU_HAS_SAMPLES(PCPU_GET(cpuid)))
                PMC_CALL_HOOK_UNLOCKED(curthread, PMC_FN_DO_SAMPLES, NULL);
        if (td->td_intr_frame != NULL)
                PMC_SOFT_CALL_TF( , , clock, hard, td->td_intr_frame);
#endif
        callout_tick();
        /* We are in charge to handle this tick duty. */
        if (newticks > 0) {
                /* Dangerous and no need to call these things concurrently. */
                if (atomic_cmpset_acq_int(&global_hardclock_run, 0, 1)) {
                        tc_ticktock(newticks);
#ifdef DEVICE_POLLING
                        /* This is very short and quick. */
                        hardclock_device_poll();
#endif /* DEVICE_POLLING */
                        atomic_store_rel_int(&global_hardclock_run, 0);
                }
#ifdef SW_WATCHDOG
                if (watchdog_enabled > 0) {
                        i = atomic_fetchadd_int(&watchdog_ticks, -newticks);
                        if (i > 0 && i <= newticks)
                                watchdog_fire();
                }
#endif /* SW_WATCHDOG */
        }
        if (curcpu == CPU_FIRST())
                cpu_tick_calibration();
}

void
hardclock_sync(int cpu)
{
        int     *t = DPCPU_ID_PTR(cpu, pcputicks);

        *t = ticks;
}

/*
 * Compute number of ticks in the specified amount of time.
 */
int
tvtohz(tv)
        struct timeval *tv;
{
        register unsigned long ticks;
        register long sec, usec;

        /*
         * If the number of usecs in the whole seconds part of the time
         * difference fits in a long, then the total number of usecs will
         * fit in an unsigned long.  Compute the total and convert it to
         * ticks, rounding up and adding 1 to allow for the current tick
         * to expire.  Rounding also depends on unsigned long arithmetic
         * to avoid overflow.
         *
         * Otherwise, if the number of ticks in the whole seconds part of
         * the time difference fits in a long, then convert the parts to
         * ticks separately and add, using similar rounding methods and
         * overflow avoidance.  This method would work in the previous
         * case but it is slightly slower and assumes that hz is integral.
         *
         * Otherwise, round the time difference down to the maximum
         * representable value.
         *
         * If ints have 32 bits, then the maximum value for any timeout in
         * 10ms ticks is 248 days.
         */
        sec = tv->tv_sec;
        usec = tv->tv_usec;
        if (usec < 0) {
                sec--;
                usec += 1000000;
        }
        if (sec < 0) {
#ifdef DIAGNOSTIC
                if (usec > 0) {
                        sec++;
                        usec -= 1000000;
                }
                printf("tvotohz: negative time difference %ld sec %ld usec\n",
                       sec, usec);
#endif
                ticks = 1;
        } else if (sec <= LONG_MAX / 1000000)
                ticks = (sec * 1000000 + (unsigned long)usec + (tick - 1))
                        / tick + 1;
        else if (sec <= LONG_MAX / hz)
                ticks = sec * hz
                        + ((unsigned long)usec + (tick - 1)) / tick + 1;
        else
                ticks = LONG_MAX;
        if (ticks > INT_MAX)
                ticks = INT_MAX;
        return ((int)ticks);
}

/*
 * Start profiling on a process.
 *
 * Kernel profiling passes proc0 which never exits and hence
 * keeps the profile clock running constantly.
 */
void
startprofclock(p)
        register struct proc *p;
{

        PROC_LOCK_ASSERT(p, MA_OWNED);
        if (p->p_flag & P_STOPPROF)
                return;
        if ((p->p_flag & P_PROFIL) == 0) {
                p->p_flag |= P_PROFIL;
                mtx_lock(&time_lock);
                if (++profprocs == 1)
                        cpu_startprofclock();
                mtx_unlock(&time_lock);
        }
}

/*
 * Stop profiling on a process.
 */
void
stopprofclock(p)
        register struct proc *p;
{

        PROC_LOCK_ASSERT(p, MA_OWNED);
        if (p->p_flag & P_PROFIL) {
                if (p->p_profthreads != 0) {
                        p->p_flag |= P_STOPPROF;
                        while (p->p_profthreads != 0)
                                msleep(&p->p_profthreads, &p->p_mtx, PPAUSE,
                                    "stopprof", 0);
                        p->p_flag &= ~P_STOPPROF;
                }
                if ((p->p_flag & P_PROFIL) == 0)
                        return;
                p->p_flag &= ~P_PROFIL;
                mtx_lock(&time_lock);
                if (--profprocs == 0)
                        cpu_stopprofclock();
                mtx_unlock(&time_lock);
        }
}

/*
 * Statistics clock.  Updates rusage information and calls the scheduler
 * to adjust priorities of the active thread.
 *
 * This should be called by all active processors.
 */
void
statclock(int usermode)
{

        statclock_cnt(1, usermode);
}

void
statclock_cnt(int cnt, int usermode)
{
        struct rusage *ru;
        struct vmspace *vm;
        struct thread *td;
        struct proc *p;
        long rss;
        long *cp_time;

        td = curthread;
        p = td->td_proc;

        cp_time = (long *)PCPU_PTR(cp_time);
        if (usermode) {
                /*
                 * Charge the time as appropriate.
                 */
                td->td_uticks += cnt;
                if (p->p_nice > NZERO)
                        cp_time[CP_NICE] += cnt;
                else
                        cp_time[CP_USER] += cnt;
        } else {
                /*
                 * Came from kernel mode, so we were:
                 * - handling an interrupt,
                 * - doing syscall or trap work on behalf of the current
                 *   user process, or
                 * - spinning in the idle loop.
                 * Whichever it is, charge the time as appropriate.
                 * Note that we charge interrupts to the current process,
                 * regardless of whether they are ``for'' that process,
                 * so that we know how much of its real time was spent
                 * in ``non-process'' (i.e., interrupt) work.
                 */
                if ((td->td_pflags & TDP_ITHREAD) ||
                    td->td_intr_nesting_level >= 2) {
                        td->td_iticks += cnt;
                        cp_time[CP_INTR] += cnt;
                } else {
                        td->td_pticks += cnt;
                        td->td_sticks += cnt;
                        if (!TD_IS_IDLETHREAD(td))
                                cp_time[CP_SYS] += cnt;
                        else
                                cp_time[CP_IDLE] += cnt;
                }
        }

        /* Update resource usage integrals and maximums. */
        MPASS(p->p_vmspace != NULL);
        vm = p->p_vmspace;
        ru = &td->td_ru;
        ru->ru_ixrss += pgtok(vm->vm_tsize) * cnt;
        ru->ru_idrss += pgtok(vm->vm_dsize) * cnt;
        ru->ru_isrss += pgtok(vm->vm_ssize) * cnt;
        rss = pgtok(vmspace_resident_count(vm));
        if (ru->ru_maxrss < rss)
                ru->ru_maxrss = rss;
        KTR_POINT2(KTR_SCHED, "thread", sched_tdname(td), "statclock",
            "prio:%d", td->td_priority, "stathz:%d", (stathz)?stathz:hz);
        SDT_PROBE2(sched, , , tick, td, td->td_proc);
        thread_lock_flags(td, MTX_QUIET);
        for ( ; cnt > 0; cnt--)
                sched_clock(td);
        thread_unlock(td);
#ifdef HWPMC_HOOKS
        if (td->td_intr_frame != NULL)
                PMC_SOFT_CALL_TF( , , clock, stat, td->td_intr_frame);
#endif
}

void
profclock(int usermode, uintfptr_t pc)
{

        profclock_cnt(1, usermode, pc);
}

void
profclock_cnt(int cnt, int usermode, uintfptr_t pc)
{
        struct thread *td;
#ifdef GPROF
        struct gmonparam *g;
        uintfptr_t i;
#endif

        td = curthread;
        if (usermode) {
                /*
                 * Came from user mode; CPU was in user state.
                 * If this process is being profiled, record the tick.
                 * if there is no related user location yet, don't
                 * bother trying to count it.
                 */
                if (td->td_proc->p_flag & P_PROFIL)
                        addupc_intr(td, pc, cnt);
        }
#ifdef GPROF
        else {
                /*
                 * Kernel statistics are just like addupc_intr, only easier.
                 */
                g = &_gmonparam;
                if (g->state == GMON_PROF_ON && pc >= g->lowpc) {
                        i = PC_TO_I(g, pc);
                        if (i < g->textsize) {
                                KCOUNT(g, i) += cnt;
                        }
                }
        }
#endif
#ifdef HWPMC_HOOKS
        if (td->td_intr_frame != NULL)
                PMC_SOFT_CALL_TF( , , clock, prof, td->td_intr_frame);
#endif
}

/*
 * Return information about system clocks.
 */
static int
sysctl_kern_clockrate(SYSCTL_HANDLER_ARGS)
{
        struct clockinfo clkinfo;
        /*
         * Construct clockinfo structure.
         */
        bzero(&clkinfo, sizeof(clkinfo));
        clkinfo.hz = hz;
        clkinfo.tick = tick;
        clkinfo.profhz = profhz;
        clkinfo.stathz = stathz ? stathz : hz;
        return (sysctl_handle_opaque(oidp, &clkinfo, sizeof clkinfo, req));
}

SYSCTL_PROC(_kern, KERN_CLOCKRATE, clockrate,
        CTLTYPE_STRUCT|CTLFLAG_RD|CTLFLAG_MPSAFE,
        0, 0, sysctl_kern_clockrate, "S,clockinfo",
        "Rate and period of various kernel clocks");

#ifdef SW_WATCHDOG

static void
watchdog_config(void *unused __unused, u_int cmd, int *error)
{
        u_int u;

        u = cmd & WD_INTERVAL;
        if (u >= WD_TO_1SEC) {
                watchdog_ticks = (1 << (u - WD_TO_1SEC)) * hz;
                watchdog_enabled = 1;
                *error = 0;
        } else {
                watchdog_enabled = 0;
        }
}

/*
 * Handle a watchdog timeout by dumping interrupt information and
 * then either dropping to DDB or panicking.
 */
static void
watchdog_fire(void)
{
        int nintr;
        uint64_t inttotal;
        u_long *curintr;
        char *curname;

        curintr = intrcnt;
        curname = intrnames;
        inttotal = 0;
        nintr = sintrcnt / sizeof(u_long);

        printf("interrupt                   total\n");
        while (--nintr >= 0) {
                if (*curintr)
                        printf("%-12s %20lu\n", curname, *curintr);
                curname += strlen(curname) + 1;
                inttotal += *curintr++;
        }
        printf("Total        %20ju\n", (uintmax_t)inttotal);

#if defined(KDB) && !defined(KDB_UNATTENDED)
        kdb_backtrace();
        kdb_enter(KDB_WHY_WATCHDOG, "watchdog timeout");
#else
        panic("watchdog timeout");
#endif
}

#endif /* SW_WATCHDOG */