kern_clock.c

Go to the documentation of this file.

/*-
 * SPDX-License-Identifier: BSD-3-Clause
 *
 * 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.
 * 3. 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("$FreeBSD$");
 
#include "opt_kdb.h"
#include "opt_device_polling.h"
#include "opt_hwpmc_hooks.h"
#include "opt_ntp.h"
#include "opt_watchdog.h"
 
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/callout.h>
#include <sys/epoch.h>
#include <sys/eventhandler.h>
#include <sys/gtaskqueue.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 */
 
/* 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
deadlres_td_on_lock(struct proc *p, struct thread *td, int blkticks)
{
        int tticks;
 
        sx_assert(&allproc_lock, SX_LOCKED);
        PROC_LOCK_ASSERT(p, MA_OWNED);
        THREAD_LOCK_ASSERT(td, MA_OWNED);
        /*
         * 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;
        if (tticks > blkticks)
                /*
                 * Accordingly with provided thresholds, this thread is stuck
                 * for too long on a turnstile.
                 */
                panic("%s: possible deadlock detected for %p (%s), "
                    "blocked for %d ticks\n", __func__,
                    td, sched_tdname(td), tticks);
}
 
static void
deadlres_td_sleep_q(struct proc *p, struct thread *td, int slpticks)
{
        const void *wchan;
        int i, slptype, tticks;
 
        sx_assert(&allproc_lock, SX_LOCKED);
        PROC_LOCK_ASSERT(p, MA_OWNED);
        THREAD_LOCK_ASSERT(td, MA_OWNED);
        /*
         * 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;
        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.
                 */
                for (i = 0; blessed[i] != NULL; i++)
                        if (!strcmp(blessed[i], td->td_wmesg))
                                return;
 
                panic("%s: possible deadlock detected for %p (%s), "
                    "blocked for %d ticks\n", __func__,
                    td, sched_tdname(td), tticks);
        }
}
 
static void
deadlkres(void)
{
        struct proc *p;
        struct thread *td;
        int blkticks, slpticks, tryl;
 
        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) {
                                thread_lock(td);
                                if (TD_ON_LOCK(td))
                                        deadlres_td_on_lock(p, td,
                                            blkticks);
                                else if (TD_IS_SLEEPING(td))
                                        deadlres_td_sleep_q(p, td,
                                            slpticks);
                                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 | CTLFLAG_MPSAFE, 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];
        }
}
 
#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 *);
 
static void
watchdog_attach(void)
{
        EVENTHANDLER_REGISTER(watchdog_list, watchdog_config, NULL, 0);
}
 
/*
 * 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;
 
DPCPU_DEFINE_STATIC(int, pcputicks);    /* Per-CPU version of ticks. */
#ifdef DEVICE_POLLING
static int devpoll_run = 0;
#endif
 
/*
 * Initialize clock frequencies and start both clocks running.
 */
static void
initclocks(void *dummy __unused)
{
        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
        /* Enable hardclock watchdog now, even if a hardware watchdog exists. */
        watchdog_attach();
#else
        /* Volunteer to run a software watchdog. */
        if (wdog_software_attach == NULL)
                wdog_software_attach = watchdog_attach;
#endif
}
SYSINIT(clocks, SI_SUB_CLOCKS, SI_ORDER_FIRST, initclocks, NULL);
 
static __noinline void
hardclock_itimer(struct thread *td, struct pstats *pstats, int cnt, int usermode)
{
        struct proc *p;
        int flags;
 
        flags = 0;
        p = td->td_proc;
        if (usermode &&
            timevalisset(&pstats->p_timer[ITIMER_VIRTUAL].it_value)) {
                PROC_ITIMLOCK(p);
                if (itimerdecr(&pstats->p_timer[ITIMER_VIRTUAL],
                    tick * cnt) == 0)
                        flags |= TDF_ALRMPEND | TDF_ASTPENDING;
                PROC_ITIMUNLOCK(p);
        }
        if (timevalisset(&pstats->p_timer[ITIMER_PROF].it_value)) {
                PROC_ITIMLOCK(p);
                if (itimerdecr(&pstats->p_timer[ITIMER_PROF],
                    tick * cnt) == 0)
                        flags |= TDF_PROFPEND | TDF_ASTPENDING;
                PROC_ITIMUNLOCK(p);
        }
        if (flags != 0) {
                thread_lock(td);
                td->td_flags |= flags;
                thread_unlock(td);
        }
}
 
void
hardclock(int cnt, int usermode)
{
        struct pstats *pstats;
        struct thread *td = curthread;
        struct proc *p = td->td_proc;
        int *t = DPCPU_PTR(pcputicks);
        int global, i, newticks;
 
        /*
         * Update per-CPU and possibly global ticks values.
         */
        *t += cnt;
        global = ticks;
        do {
                newticks = *t - global;
                if (newticks <= 0) {
                        if (newticks < -1)
                                *t = global - 1;
                        newticks = 0;
                        break;
                }
        } while (!atomic_fcmpset_int(&ticks, &global, *t));
 
        /*
         * Run current process's virtual and profile time, as needed.
         */
        pstats = p->p_stats;
        if (__predict_false(
            timevalisset(&pstats->p_timer[ITIMER_VIRTUAL].it_value) ||
            timevalisset(&pstats->p_timer[ITIMER_PROF].it_value)))
                hardclock_itimer(td, pstats, cnt, usermode);
 
#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
        /* We are in charge to handle this tick duty. */
        if (newticks > 0) {
                tc_ticktock(newticks);
#ifdef DEVICE_POLLING
                /* Dangerous and no need to call these things concurrently. */
                if (atomic_cmpset_acq_int(&devpoll_run, 0, 1)) {
                        /* This is very short and quick. */
                        hardclock_device_poll();
                        atomic_store_rel_int(&devpoll_run, 0);
                }
#endif /* DEVICE_POLLING */
                if (watchdog_enabled > 0) {
                        i = atomic_fetchadd_int(&watchdog_ticks, -newticks);
                        if (i > 0 && i <= newticks)
                                watchdog_fire();
                }
                intr_event_handle(clk_intr_event, NULL);
        }
        if (curcpu == CPU_FIRST())
                cpu_tick_calibration();
        if (__predict_false(DPCPU_GET(epoch_cb_count)))
                GROUPTASK_ENQUEUE(DPCPU_PTR(epoch_cb_task));
}
 
void
hardclock_sync(int cpu)
{
        int *t;
        KASSERT(!CPU_ABSENT(cpu), ("Absent CPU %d", cpu));
        t = DPCPU_ID_PTR(cpu, pcputicks);
 
        *t = ticks;
}
 
/*
 * Compute number of ticks in the specified amount of time.
 */
int
tvtohz(struct timeval *tv)
{
        unsigned long ticks;
        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 = howmany(sec * 1000000 + (unsigned long)usec, tick) + 1;
        else if (sec <= LONG_MAX / hz)
                ticks = sec * hz
                        + howmany((unsigned long)usec, 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(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(struct proc *p)
{
 
        PROC_LOCK_ASSERT(p, MA_OWNED);
        if (p->p_flag & P_PROFIL) {
                if (p->p_profthreads != 0) {
                        while (p->p_profthreads != 0) {
                                p->p_flag |= P_STOPPROF;
                                msleep(&p->p_profthreads, &p->p_mtx, PPAUSE,
                                    "stopprof", 0);
                        }
                }
                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 cnt, int usermode)
{
        struct rusage *ru;
        struct vmspace *vm;
        struct thread *td;
        struct proc *p;
        long rss;
        long *cp_time;
        uint64_t runtime, new_switchtime;
 
        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);
 
        /*
         * Compute the amount of time during which the current
         * thread was running, and add that to its total so far.
         */
        new_switchtime = cpu_ticks();
        runtime = new_switchtime - PCPU_GET(switchtime);
        td->td_runtime += runtime;
        td->td_incruntime += runtime;
        PCPU_SET(switchtime, new_switchtime);
 
        sched_clock(td, cnt);
        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 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");
 
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
}