kern_clocksource.c

Go to the documentation of this file.

/*-
 * Copyright (c) 2010-2012 Alexander Motin <mav@FreeBSD.org>
 * All rights reserved.
 *
 * 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,
 *    without modification, immediately at the beginning of the file.
 * 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.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 AUTHOR 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.
 */

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

/*
 * Common routines to manage event timers hardware.
 */

#include "opt_device_polling.h"
#include "opt_kdtrace.h"

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/bus.h>
#include <sys/lock.h>
#include <sys/kdb.h>
#include <sys/ktr.h>
#include <sys/mutex.h>
#include <sys/proc.h>
#include <sys/kernel.h>
#include <sys/sched.h>
#include <sys/smp.h>
#include <sys/sysctl.h>
#include <sys/timeet.h>
#include <sys/timetc.h>

#include <machine/atomic.h>
#include <machine/clock.h>
#include <machine/cpu.h>
#include <machine/smp.h>

#ifdef KDTRACE_HOOKS
#include <sys/dtrace_bsd.h>
cyclic_clock_func_t     cyclic_clock_func = NULL;
#endif

int                     cpu_deepest_sleep = 0;  /* Deepest Cx state available. */
int                     cpu_disable_c2_sleep = 0; /* Timer dies in C2. */
int                     cpu_disable_c3_sleep = 0; /* Timer dies in C3. */

static void             setuptimer(void);
static void             loadtimer(struct bintime *now, int first);
static int              doconfigtimer(void);
static void             configtimer(int start);
static int              round_freq(struct eventtimer *et, int freq);

static void             getnextcpuevent(struct bintime *event, int idle);
static void             getnextevent(struct bintime *event);
static int              handleevents(struct bintime *now, int fake);
#ifdef SMP
static void             cpu_new_callout(int cpu, int ticks);
#endif

static struct mtx       et_hw_mtx;

#define ET_HW_LOCK(state)                                               \
        {                                                               \
                if (timer->et_flags & ET_FLAGS_PERCPU)                  \
                        mtx_lock_spin(&(state)->et_hw_mtx);             \
                else                                                    \
                        mtx_lock_spin(&et_hw_mtx);                      \
        }

#define ET_HW_UNLOCK(state)                                             \
        {                                                               \
                if (timer->et_flags & ET_FLAGS_PERCPU)                  \
                        mtx_unlock_spin(&(state)->et_hw_mtx);           \
                else                                                    \
                        mtx_unlock_spin(&et_hw_mtx);                    \
        }

static struct eventtimer *timer = NULL;
static struct bintime   timerperiod;    /* Timer period for periodic mode. */
static struct bintime   hardperiod;     /* hardclock() events period. */
static struct bintime   statperiod;     /* statclock() events period. */
static struct bintime   profperiod;     /* profclock() events period. */
static struct bintime   nexttick;       /* Next global timer tick time. */
static struct bintime   nexthard;       /* Next global hardlock() event. */
static u_int            busy = 0;       /* Reconfiguration is in progress. */
static int              profiling = 0;  /* Profiling events enabled. */

static char             timername[32];  /* Wanted timer. */
TUNABLE_STR("kern.eventtimer.timer", timername, sizeof(timername));

static int              singlemul = 0;  /* Multiplier for periodic mode. */
TUNABLE_INT("kern.eventtimer.singlemul", &singlemul);
SYSCTL_INT(_kern_eventtimer, OID_AUTO, singlemul, CTLFLAG_RW, &singlemul,
    0, "Multiplier for periodic mode");

static u_int            idletick = 0;   /* Run periodic events when idle. */
TUNABLE_INT("kern.eventtimer.idletick", &idletick);
SYSCTL_UINT(_kern_eventtimer, OID_AUTO, idletick, CTLFLAG_RW, &idletick,
    0, "Run periodic events when idle");

static u_int            activetick = 1; /* Run all periodic events when active. */
TUNABLE_INT("kern.eventtimer.activetick", &activetick);
SYSCTL_UINT(_kern_eventtimer, OID_AUTO, activetick, CTLFLAG_RW, &activetick,
    0, "Run all periodic events when active");

static int              periodic = 0;   /* Periodic or one-shot mode. */
static int              want_periodic = 0; /* What mode to prefer. */
TUNABLE_INT("kern.eventtimer.periodic", &want_periodic);

struct pcpu_state {
        struct mtx      et_hw_mtx;      /* Per-CPU timer mutex. */
        u_int           action;         /* Reconfiguration requests. */
        u_int           handle;         /* Immediate handle resuests. */
        struct bintime  now;            /* Last tick time. */
        struct bintime  nextevent;      /* Next scheduled event on this CPU. */
        struct bintime  nexttick;       /* Next timer tick time. */
        struct bintime  nexthard;       /* Next hardlock() event. */
        struct bintime  nextstat;       /* Next statclock() event. */
        struct bintime  nextprof;       /* Next profclock() event. */
#ifdef KDTRACE_HOOKS
        struct bintime  nextcyc;        /* Next OpenSolaris cyclics event. */
#endif
        int             ipi;            /* This CPU needs IPI. */
        int             idle;           /* This CPU is in idle mode. */
};

static DPCPU_DEFINE(struct pcpu_state, timerstate);

#define FREQ2BT(freq, bt)                                               \
{                                                                       \
        (bt)->sec = 0;                                                  \
        (bt)->frac = ((uint64_t)0x8000000000000000  / (freq)) << 1;     \
}
#define BT2FREQ(bt)                                                     \
        (((uint64_t)0x8000000000000000 + ((bt)->frac >> 2)) /           \
            ((bt)->frac >> 1))

/*
 * Timer broadcast IPI handler.
 */
int
hardclockintr(void)
{
        struct bintime now;
        struct pcpu_state *state;
        int done;

        if (doconfigtimer() || busy)
                return (FILTER_HANDLED);
        state = DPCPU_PTR(timerstate);
        now = state->now;
        CTR4(KTR_SPARE2, "ipi  at %d:    now  %d.%08x%08x",
            curcpu, now.sec, (unsigned int)(now.frac >> 32),
                             (unsigned int)(now.frac & 0xffffffff));
        done = handleevents(&now, 0);
        return (done ? FILTER_HANDLED : FILTER_STRAY);
}

/*
 * Handle all events for specified time on this CPU
 */
static int
handleevents(struct bintime *now, int fake)
{
        struct bintime t;
        struct trapframe *frame;
        struct pcpu_state *state;
        uintfptr_t pc;
        int usermode;
        int done, runs;

        CTR4(KTR_SPARE2, "handle at %d:  now  %d.%08x%08x",
            curcpu, now->sec, (unsigned int)(now->frac >> 32),
                     (unsigned int)(now->frac & 0xffffffff));
        done = 0;
        if (fake) {
                frame = NULL;
                usermode = 0;
                pc = 0;
        } else {
                frame = curthread->td_intr_frame;
                usermode = TRAPF_USERMODE(frame);
                pc = TRAPF_PC(frame);
        }

        state = DPCPU_PTR(timerstate);

        runs = 0;
        while (bintime_cmp(now, &state->nexthard, >=)) {
                bintime_add(&state->nexthard, &hardperiod);
                runs++;
        }
        if ((timer->et_flags & ET_FLAGS_PERCPU) == 0 &&
            bintime_cmp(&state->nexthard, &nexthard, >))
                nexthard = state->nexthard;
        if (runs && fake < 2) {
                hardclock_cnt(runs, usermode);
                done = 1;
        }
        runs = 0;
        while (bintime_cmp(now, &state->nextstat, >=)) {
                bintime_add(&state->nextstat, &statperiod);
                runs++;
        }
        if (runs && fake < 2) {
                statclock_cnt(runs, usermode);
                done = 1;
        }
        if (profiling) {
                runs = 0;
                while (bintime_cmp(now, &state->nextprof, >=)) {
                        bintime_add(&state->nextprof, &profperiod);
                        runs++;
                }
                if (runs && !fake) {
                        profclock_cnt(runs, usermode, pc);
                        done = 1;
                }
        } else
                state->nextprof = state->nextstat;

#ifdef KDTRACE_HOOKS
        if (fake == 0 && cyclic_clock_func != NULL &&
            state->nextcyc.sec != -1 &&
            bintime_cmp(now, &state->nextcyc, >=)) {
                state->nextcyc.sec = -1;
                (*cyclic_clock_func)(frame);
        }
#endif

        getnextcpuevent(&t, 0);
        if (fake == 2) {
                state->nextevent = t;
                return (done);
        }
        ET_HW_LOCK(state);
        if (!busy) {
                state->idle = 0;
                state->nextevent = t;
                loadtimer(now, 0);
        }
        ET_HW_UNLOCK(state);
        return (done);
}

/*
 * Schedule binuptime of the next event on current CPU.
 */
static void
getnextcpuevent(struct bintime *event, int idle)
{
        struct bintime tmp;
        struct pcpu_state *state;
        int skip;

        state = DPCPU_PTR(timerstate);
        /* Handle hardclock() events. */
        *event = state->nexthard;
        if (idle || (!activetick && !profiling &&
            (timer->et_flags & ET_FLAGS_PERCPU) == 0)) {
                skip = idle ? 4 : (stathz / 2);
                if (curcpu == CPU_FIRST() && tc_min_ticktock_freq > skip)
                        skip = tc_min_ticktock_freq;
                skip = callout_tickstofirst(hz / skip) - 1;
                CTR2(KTR_SPARE2, "skip   at %d: %d", curcpu, skip);
                tmp = hardperiod;
                bintime_mul(&tmp, skip);
                bintime_add(event, &tmp);
        }
        if (!idle) { /* If CPU is active - handle other types of events. */
                if (bintime_cmp(event, &state->nextstat, >))
                        *event = state->nextstat;
                if (profiling && bintime_cmp(event, &state->nextprof, >))
                        *event = state->nextprof;
        }
#ifdef KDTRACE_HOOKS
        if (state->nextcyc.sec != -1 && bintime_cmp(event, &state->nextcyc, >))
                *event = state->nextcyc;
#endif
}

/*
 * Schedule binuptime of the next event on all CPUs.
 */
static void
getnextevent(struct bintime *event)
{
        struct pcpu_state *state;
#ifdef SMP
        int     cpu;
#endif
        int     c, nonidle;

        state = DPCPU_PTR(timerstate);
        *event = state->nextevent;
        c = curcpu;
        nonidle = !state->idle;
        if ((timer->et_flags & ET_FLAGS_PERCPU) == 0) {
#ifdef SMP
                CPU_FOREACH(cpu) {
                        if (curcpu == cpu)
                                continue;
                        state = DPCPU_ID_PTR(cpu, timerstate);
                        nonidle += !state->idle;
                        if (bintime_cmp(event, &state->nextevent, >)) {
                                *event = state->nextevent;
                                c = cpu;
                        }
                }
#endif
                if (nonidle != 0 && bintime_cmp(event, &nexthard, >))
                        *event = nexthard;
        }
        CTR5(KTR_SPARE2, "next at %d:    next %d.%08x%08x by %d",
            curcpu, event->sec, (unsigned int)(event->frac >> 32),
                             (unsigned int)(event->frac & 0xffffffff), c);
}

/* Hardware timer callback function. */
static void
timercb(struct eventtimer *et, void *arg)
{
        struct bintime now;
        struct bintime *next;
        struct pcpu_state *state;
#ifdef SMP
        int cpu, bcast;
#endif

        /* Do not touch anything if somebody reconfiguring timers. */
        if (busy)
                return;
        /* Update present and next tick times. */
        state = DPCPU_PTR(timerstate);
        if (et->et_flags & ET_FLAGS_PERCPU) {
                next = &state->nexttick;
        } else
                next = &nexttick;
        if (periodic) {
                now = *next;    /* Ex-next tick time becomes present time. */
                bintime_add(next, &timerperiod); /* Next tick in 1 period. */
        } else {
                binuptime(&now);        /* Get present time from hardware. */
                next->sec = -1;         /* Next tick is not scheduled yet. */
        }
        state->now = now;
        CTR4(KTR_SPARE2, "intr at %d:    now  %d.%08x%08x",
            curcpu, now.sec, (unsigned int)(now.frac >> 32),
                             (unsigned int)(now.frac & 0xffffffff));

#ifdef SMP
        /* Prepare broadcasting to other CPUs for non-per-CPU timers. */
        bcast = 0;
        if ((et->et_flags & ET_FLAGS_PERCPU) == 0 && smp_started) {
                CPU_FOREACH(cpu) {
                        state = DPCPU_ID_PTR(cpu, timerstate);
                        ET_HW_LOCK(state);
                        state->now = now;
                        if (bintime_cmp(&now, &state->nextevent, >=)) {
                                state->nextevent.sec++;
                                if (curcpu != cpu) {
                                        state->ipi = 1;
                                        bcast = 1;
                                }
                        }
                        ET_HW_UNLOCK(state);
                }
        }
#endif

        /* Handle events for this time on this CPU. */
        handleevents(&now, 0);

#ifdef SMP
        /* Broadcast interrupt to other CPUs for non-per-CPU timers. */
        if (bcast) {
                CPU_FOREACH(cpu) {
                        if (curcpu == cpu)
                                continue;
                        state = DPCPU_ID_PTR(cpu, timerstate);
                        if (state->ipi) {
                                state->ipi = 0;
                                ipi_cpu(cpu, IPI_HARDCLOCK);
                        }
                }
        }
#endif
}

/*
 * Load new value into hardware timer.
 */
static void
loadtimer(struct bintime *now, int start)
{
        struct pcpu_state *state;
        struct bintime new;
        struct bintime *next;
        uint64_t tmp;
        int eq;

        if (timer->et_flags & ET_FLAGS_PERCPU) {
                state = DPCPU_PTR(timerstate);
                next = &state->nexttick;
        } else
                next = &nexttick;
        if (periodic) {
                if (start) {
                        /*
                         * Try to start all periodic timers aligned
                         * to period to make events synchronous.
                         */
                        tmp = ((uint64_t)now->sec << 36) + (now->frac >> 28);
                        tmp = (tmp % (timerperiod.frac >> 28)) << 28;
                        new.sec = 0;
                        new.frac = timerperiod.frac - tmp;
                        if (new.frac < tmp)     /* Left less then passed. */
                                bintime_add(&new, &timerperiod);
                        CTR5(KTR_SPARE2, "load p at %d:   now %d.%08x first in %d.%08x",
                            curcpu, now->sec, (unsigned int)(now->frac >> 32),
                            new.sec, (unsigned int)(new.frac >> 32));
                        *next = new;
                        bintime_add(next, now);
                        et_start(timer, &new, &timerperiod);
                }
        } else {
                getnextevent(&new);
                eq = bintime_cmp(&new, next, ==);
                CTR5(KTR_SPARE2, "load at %d:    next %d.%08x%08x eq %d",
                    curcpu, new.sec, (unsigned int)(new.frac >> 32),
                             (unsigned int)(new.frac & 0xffffffff),
                             eq);
                if (!eq) {
                        *next = new;
                        bintime_sub(&new, now);
                        et_start(timer, &new, NULL);
                }
        }
}

/*
 * Prepare event timer parameters after configuration changes.
 */
static void
setuptimer(void)
{
        int freq;

        if (periodic && (timer->et_flags & ET_FLAGS_PERIODIC) == 0)
                periodic = 0;
        else if (!periodic && (timer->et_flags & ET_FLAGS_ONESHOT) == 0)
                periodic = 1;
        singlemul = MIN(MAX(singlemul, 1), 20);
        freq = hz * singlemul;
        while (freq < (profiling ? profhz : stathz))
                freq += hz;
        freq = round_freq(timer, freq);
        FREQ2BT(freq, &timerperiod);
}

/*
 * Reconfigure specified per-CPU timer on other CPU. Called from IPI handler.
 */
static int
doconfigtimer(void)
{
        struct bintime now;
        struct pcpu_state *state;

        state = DPCPU_PTR(timerstate);
        switch (atomic_load_acq_int(&state->action)) {
        case 1:
                binuptime(&now);
                ET_HW_LOCK(state);
                loadtimer(&now, 1);
                ET_HW_UNLOCK(state);
                state->handle = 0;
                atomic_store_rel_int(&state->action, 0);
                return (1);
        case 2:
                ET_HW_LOCK(state);
                et_stop(timer);
                ET_HW_UNLOCK(state);
                state->handle = 0;
                atomic_store_rel_int(&state->action, 0);
                return (1);
        }
        if (atomic_readandclear_int(&state->handle) && !busy) {
                binuptime(&now);
                handleevents(&now, 0);
                return (1);
        }
        return (0);
}

/*
 * Reconfigure specified timer.
 * For per-CPU timers use IPI to make other CPUs to reconfigure.
 */
static void
configtimer(int start)
{
        struct bintime now, next;
        struct pcpu_state *state;
        int cpu;

        if (start) {
                setuptimer();
                binuptime(&now);
        }
        critical_enter();
        ET_HW_LOCK(DPCPU_PTR(timerstate));
        if (start) {
                /* Initialize time machine parameters. */
                next = now;
                bintime_add(&next, &timerperiod);
                if (periodic)
                        nexttick = next;
                else
                        nexttick.sec = -1;
                CPU_FOREACH(cpu) {
                        state = DPCPU_ID_PTR(cpu, timerstate);
                        state->now = now;
                        state->nextevent = next;
                        if (periodic)
                                state->nexttick = next;
                        else
                                state->nexttick.sec = -1;
                        state->nexthard = next;
                        state->nextstat = next;
                        state->nextprof = next;
                        hardclock_sync(cpu);
                }
                busy = 0;
                /* Start global timer or per-CPU timer of this CPU. */
                loadtimer(&now, 1);
        } else {
                busy = 1;
                /* Stop global timer or per-CPU timer of this CPU. */
                et_stop(timer);
        }
        ET_HW_UNLOCK(DPCPU_PTR(timerstate));
#ifdef SMP
        /* If timer is global or there is no other CPUs yet - we are done. */
        if ((timer->et_flags & ET_FLAGS_PERCPU) == 0 || !smp_started) {
                critical_exit();
                return;
        }
        /* Set reconfigure flags for other CPUs. */
        CPU_FOREACH(cpu) {
                state = DPCPU_ID_PTR(cpu, timerstate);
                atomic_store_rel_int(&state->action,
                    (cpu == curcpu) ? 0 : ( start ? 1 : 2));
        }
        /* Broadcast reconfigure IPI. */
        ipi_all_but_self(IPI_HARDCLOCK);
        /* Wait for reconfiguration completed. */
restart:
        cpu_spinwait();
        CPU_FOREACH(cpu) {
                if (cpu == curcpu)
                        continue;
                state = DPCPU_ID_PTR(cpu, timerstate);
                if (atomic_load_acq_int(&state->action))
                        goto restart;
        }
#endif
        critical_exit();
}

/*
 * Calculate nearest frequency supported by hardware timer.
 */
static int
round_freq(struct eventtimer *et, int freq)
{
        uint64_t div;

        if (et->et_frequency != 0) {
                div = lmax((et->et_frequency + freq / 2) / freq, 1);
                if (et->et_flags & ET_FLAGS_POW2DIV)
                        div = 1 << (flsl(div + div / 2) - 1);
                freq = (et->et_frequency + div / 2) / div;
        }
        if (et->et_min_period.sec > 0)
                freq = 0;
        else if (et->et_min_period.frac != 0)
                freq = min(freq, BT2FREQ(&et->et_min_period));
        if (et->et_max_period.sec == 0 && et->et_max_period.frac != 0)
                freq = max(freq, BT2FREQ(&et->et_max_period));
        return (freq);
}

/*
 * Configure and start event timers (BSP part).
 */
void
cpu_initclocks_bsp(void)
{
        struct pcpu_state *state;
        int base, div, cpu;

        mtx_init(&et_hw_mtx, "et_hw_mtx", NULL, MTX_SPIN);
        CPU_FOREACH(cpu) {
                state = DPCPU_ID_PTR(cpu, timerstate);
                mtx_init(&state->et_hw_mtx, "et_hw_mtx", NULL, MTX_SPIN);
#ifdef KDTRACE_HOOKS
                state->nextcyc.sec = -1;
#endif
        }
#ifdef SMP
        callout_new_inserted = cpu_new_callout;
#endif
        periodic = want_periodic;
        /* Grab requested timer or the best of present. */
        if (timername[0])
                timer = et_find(timername, 0, 0);
        if (timer == NULL && periodic) {
                timer = et_find(NULL,
                    ET_FLAGS_PERIODIC, ET_FLAGS_PERIODIC);
        }
        if (timer == NULL) {
                timer = et_find(NULL,
                    ET_FLAGS_ONESHOT, ET_FLAGS_ONESHOT);
        }
        if (timer == NULL && !periodic) {
                timer = et_find(NULL,
                    ET_FLAGS_PERIODIC, ET_FLAGS_PERIODIC);
        }
        if (timer == NULL)
                panic("No usable event timer found!");
        et_init(timer, timercb, NULL, NULL);

        /* Adapt to timer capabilities. */
        if (periodic && (timer->et_flags & ET_FLAGS_PERIODIC) == 0)
                periodic = 0;
        else if (!periodic && (timer->et_flags & ET_FLAGS_ONESHOT) == 0)
                periodic = 1;
        if (timer->et_flags & ET_FLAGS_C3STOP)
                cpu_disable_c3_sleep++;

        /*
         * We honor the requested 'hz' value.
         * We want to run stathz in the neighborhood of 128hz.
         * We would like profhz to run as often as possible.
         */
        if (singlemul <= 0 || singlemul > 20) {
                if (hz >= 1500 || (hz % 128) == 0)
                        singlemul = 1;
                else if (hz >= 750)
                        singlemul = 2;
                else
                        singlemul = 4;
        }
        if (periodic) {
                base = round_freq(timer, hz * singlemul);
                singlemul = max((base + hz / 2) / hz, 1);
                hz = (base + singlemul / 2) / singlemul;
                if (base <= 128)
                        stathz = base;
                else {
                        div = base / 128;
                        if (div >= singlemul && (div % singlemul) == 0)
                                div++;
                        stathz = base / div;
                }
                profhz = stathz;
                while ((profhz + stathz) <= 128 * 64)
                        profhz += stathz;
                profhz = round_freq(timer, profhz);
        } else {
                hz = round_freq(timer, hz);
                stathz = round_freq(timer, 127);
                profhz = round_freq(timer, stathz * 64);
        }
        tick = 1000000 / hz;
        FREQ2BT(hz, &hardperiod);
        FREQ2BT(stathz, &statperiod);
        FREQ2BT(profhz, &profperiod);
        ET_LOCK();
        configtimer(1);
        ET_UNLOCK();
}

/*
 * Start per-CPU event timers on APs.
 */
void
cpu_initclocks_ap(void)
{
        struct bintime now;
        struct pcpu_state *state;

        state = DPCPU_PTR(timerstate);
        binuptime(&now);
        ET_HW_LOCK(state);
        if ((timer->et_flags & ET_FLAGS_PERCPU) == 0 && periodic) {
                state->now = nexttick;
                bintime_sub(&state->now, &timerperiod);
        } else
                state->now = now;
        hardclock_sync(curcpu);
        handleevents(&state->now, 2);
        if (timer->et_flags & ET_FLAGS_PERCPU)
                loadtimer(&now, 1);
        ET_HW_UNLOCK(state);
}

/*
 * Switch to profiling clock rates.
 */
void
cpu_startprofclock(void)
{

        ET_LOCK();
        if (profiling == 0) {
                if (periodic) {
                        configtimer(0);
                        profiling = 1;
                        configtimer(1);
                } else
                        profiling = 1;
        } else
                profiling++;
        ET_UNLOCK();
}

/*
 * Switch to regular clock rates.
 */
void
cpu_stopprofclock(void)
{

        ET_LOCK();
        if (profiling == 1) {
                if (periodic) {
                        configtimer(0);
                        profiling = 0;
                        configtimer(1);
                } else
                profiling = 0;
        } else
                profiling--;
        ET_UNLOCK();
}

/*
 * Switch to idle mode (all ticks handled).
 */
void
cpu_idleclock(void)
{
        struct bintime now, t;
        struct pcpu_state *state;

        if (idletick || busy ||
            (periodic && (timer->et_flags & ET_FLAGS_PERCPU))
#ifdef DEVICE_POLLING
            || curcpu == CPU_FIRST()
#endif
            )
                return;
        state = DPCPU_PTR(timerstate);
        if (periodic)
                now = state->now;
        else
                binuptime(&now);
        CTR4(KTR_SPARE2, "idle at %d:    now  %d.%08x%08x",
            curcpu, now.sec, (unsigned int)(now.frac >> 32),
                             (unsigned int)(now.frac & 0xffffffff));
        getnextcpuevent(&t, 1);
        ET_HW_LOCK(state);
        state->idle = 1;
        state->nextevent = t;
        if (!periodic)
                loadtimer(&now, 0);
        ET_HW_UNLOCK(state);
}

/*
 * Switch to active mode (skip empty ticks).
 */
void
cpu_activeclock(void)
{
        struct bintime now;
        struct pcpu_state *state;
        struct thread *td;

        state = DPCPU_PTR(timerstate);
        if (state->idle == 0 || busy)
                return;
        if (periodic)
                now = state->now;
        else
                binuptime(&now);
        CTR4(KTR_SPARE2, "active at %d:  now  %d.%08x%08x",
            curcpu, now.sec, (unsigned int)(now.frac >> 32),
                             (unsigned int)(now.frac & 0xffffffff));
        spinlock_enter();
        td = curthread;
        td->td_intr_nesting_level++;
        handleevents(&now, 1);
        td->td_intr_nesting_level--;
        spinlock_exit();
}

#ifdef KDTRACE_HOOKS
void
clocksource_cyc_set(const struct bintime *t)
{
        struct bintime now;
        struct pcpu_state *state;

        state = DPCPU_PTR(timerstate);
        if (periodic)
                now = state->now;
        else
                binuptime(&now);

        CTR4(KTR_SPARE2, "set_cyc at %d:  now  %d.%08x%08x",
            curcpu, now.sec, (unsigned int)(now.frac >> 32),
                             (unsigned int)(now.frac & 0xffffffff));
        CTR4(KTR_SPARE2, "set_cyc at %d:  t  %d.%08x%08x",
            curcpu, t->sec, (unsigned int)(t->frac >> 32),
                             (unsigned int)(t->frac & 0xffffffff));

        ET_HW_LOCK(state);
        if (bintime_cmp(t, &state->nextcyc, ==)) {
                ET_HW_UNLOCK(state);
                return;
        }
        state->nextcyc = *t;
        if (bintime_cmp(&state->nextcyc, &state->nextevent, >=)) {
                ET_HW_UNLOCK(state);
                return;
        }
        state->nextevent = state->nextcyc;
        if (!periodic)
                loadtimer(&now, 0);
        ET_HW_UNLOCK(state);
}
#endif

#ifdef SMP
static void
cpu_new_callout(int cpu, int ticks)
{
        struct bintime tmp;
        struct pcpu_state *state;

        CTR3(KTR_SPARE2, "new co at %d:    on %d in %d",
            curcpu, cpu, ticks);
        state = DPCPU_ID_PTR(cpu, timerstate);
        ET_HW_LOCK(state);
        if (state->idle == 0 || busy) {
                ET_HW_UNLOCK(state);
                return;
        }
        /*
         * If timer is periodic - just update next event time for target CPU.
         * If timer is global - there is chance it is already programmed.
         */
        if (periodic || (timer->et_flags & ET_FLAGS_PERCPU) == 0) {
                tmp = hardperiod;
                bintime_mul(&tmp, ticks - 1);
                bintime_add(&tmp, &state->nexthard);
                if (bintime_cmp(&tmp, &state->nextevent, <))
                        state->nextevent = tmp;
                if (periodic ||
                    bintime_cmp(&state->nextevent, &nexttick, >=)) {
                        ET_HW_UNLOCK(state);
                        return;
                }
        }
        /*
         * Otherwise we have to wake that CPU up, as we can't get present
         * bintime to reprogram global timer from here. If timer is per-CPU,
         * we by definition can't do it from here.
         */
        ET_HW_UNLOCK(state);
        if (timer->et_flags & ET_FLAGS_PERCPU) {
                state->handle = 1;
                ipi_cpu(cpu, IPI_HARDCLOCK);
        } else {
                if (!cpu_idle_wakeup(cpu))
                        ipi_cpu(cpu, IPI_AST);
        }
}
#endif

/*
 * Report or change the active event timers hardware.
 */
static int
sysctl_kern_eventtimer_timer(SYSCTL_HANDLER_ARGS)
{
        char buf[32];
        struct eventtimer *et;
        int error;

        ET_LOCK();
        et = timer;
        snprintf(buf, sizeof(buf), "%s", et->et_name);
        ET_UNLOCK();
        error = sysctl_handle_string(oidp, buf, sizeof(buf), req);
        ET_LOCK();
        et = timer;
        if (error != 0 || req->newptr == NULL ||
            strcasecmp(buf, et->et_name) == 0) {
                ET_UNLOCK();
                return (error);
        }
        et = et_find(buf, 0, 0);
        if (et == NULL) {
                ET_UNLOCK();
                return (ENOENT);
        }
        configtimer(0);
        et_free(timer);
        if (et->et_flags & ET_FLAGS_C3STOP)
                cpu_disable_c3_sleep++;
        if (timer->et_flags & ET_FLAGS_C3STOP)
                cpu_disable_c3_sleep--;
        periodic = want_periodic;
        timer = et;
        et_init(timer, timercb, NULL, NULL);
        configtimer(1);
        ET_UNLOCK();
        return (error);
}
SYSCTL_PROC(_kern_eventtimer, OID_AUTO, timer,
    CTLTYPE_STRING | CTLFLAG_RW | CTLFLAG_MPSAFE,
    0, 0, sysctl_kern_eventtimer_timer, "A", "Chosen event timer");

/*
 * Report or change the active event timer periodicity.
 */
static int
sysctl_kern_eventtimer_periodic(SYSCTL_HANDLER_ARGS)
{
        int error, val;

        val = periodic;
        error = sysctl_handle_int(oidp, &val, 0, req);
        if (error != 0 || req->newptr == NULL)
                return (error);
        ET_LOCK();
        configtimer(0);
        periodic = want_periodic = val;
        configtimer(1);
        ET_UNLOCK();
        return (error);
}
SYSCTL_PROC(_kern_eventtimer, OID_AUTO, periodic,
    CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_MPSAFE,
    0, 0, sysctl_kern_eventtimer_periodic, "I", "Enable event timer periodic mode");