/*- * 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. * * From: @(#)kern_clock.c 8.5 (Berkeley) 1/21/94 */ #include __FBSDID("$FreeBSD$"); #include #include #include #include #include #include #include #include #include static int avg_depth; SYSCTL_INT(_debug, OID_AUTO, to_avg_depth, CTLFLAG_RD, &avg_depth, 0, "Average number of items examined per softclock call. Units = 1/1000"); static int avg_gcalls; SYSCTL_INT(_debug, OID_AUTO, to_avg_gcalls, CTLFLAG_RD, &avg_gcalls, 0, "Average number of Giant callouts made per softclock call. Units = 1/1000"); static int avg_mtxcalls; SYSCTL_INT(_debug, OID_AUTO, to_avg_mtxcalls, CTLFLAG_RD, &avg_mtxcalls, 0, "Average number of mtx callouts made per softclock call. Units = 1/1000"); static int avg_mpcalls; SYSCTL_INT(_debug, OID_AUTO, to_avg_mpcalls, CTLFLAG_RD, &avg_mpcalls, 0, "Average number of MP callouts made per softclock call. Units = 1/1000"); /* * TODO: * allocate more timeout table slots when table overflows. */ /* Exported to machdep.c and/or kern_clock.c. */ struct callout *callout; struct callout_list callfree; int callwheelsize, callwheelbits, callwheelmask; struct callout_tailq *callwheel; int softticks; /* Like ticks, but for softclock(). */ struct mtx callout_lock; #ifdef DIAGNOSTIC struct mtx dont_sleep_in_callout; #endif static struct callout *nextsoftcheck; /* Next callout to be checked. */ /** * Locked by callout_lock: * curr_callout - If a callout is in progress, it is curr_callout. * If curr_callout is non-NULL, threads waiting on * callout_wait will be woken up as soon as the * relevant callout completes. * curr_cancelled - Changing to 1 with both callout_lock and c_mtx held * guarantees that the current callout will not run. * The softclock() function sets this to 0 before it * drops callout_lock to acquire c_mtx, and it calls * the handler only if curr_cancelled still 0 when * c_mtx is successfully acquired. * wakeup_ctr - Incremented every time a thread wants to wait * for a callout to complete. Modified only when * curr_callout is non-NULL. * wakeup_needed - If a thread is waiting on callout_wait, then * wakeup_needed is nonzero. Increased only when * cutt_callout is non-NULL. */ static struct callout *curr_callout; static int curr_cancelled; static int wakeup_ctr; static int wakeup_needed; /** * Locked by callout_wait_lock: * callout_wait - If wakeup_needed is set, callout_wait will be * triggered after the current callout finishes. * wakeup_done_ctr - Set to the current value of wakeup_ctr after * callout_wait is triggered. */ static struct mtx callout_wait_lock; static struct cv callout_wait; static int wakeup_done_ctr; /* * kern_timeout_callwheel_alloc() - kernel low level callwheel initialization * * This code is called very early in the kernel initialization sequence, * and may be called more then once. */ caddr_t kern_timeout_callwheel_alloc(caddr_t v) { /* * Calculate callout wheel size */ for (callwheelsize = 1, callwheelbits = 0; callwheelsize < ncallout; callwheelsize <<= 1, ++callwheelbits) ; callwheelmask = callwheelsize - 1; callout = (struct callout *)v; v = (caddr_t)(callout + ncallout); callwheel = (struct callout_tailq *)v; v = (caddr_t)(callwheel + callwheelsize); return(v); } /* * kern_timeout_callwheel_init() - initialize previously reserved callwheel * space. * * This code is called just once, after the space reserved for the * callout wheel has been finalized. */ void kern_timeout_callwheel_init(void) { int i; SLIST_INIT(&callfree); for (i = 0; i < ncallout; i++) { callout_init(&callout[i], 0); callout[i].c_flags = CALLOUT_LOCAL_ALLOC; SLIST_INSERT_HEAD(&callfree, &callout[i], c_links.sle); } for (i = 0; i < callwheelsize; i++) { TAILQ_INIT(&callwheel[i]); } mtx_init(&callout_lock, "callout", NULL, MTX_SPIN | MTX_RECURSE); #ifdef DIAGNOSTIC mtx_init(&dont_sleep_in_callout, "dont_sleep_in_callout", NULL, MTX_DEF); #endif mtx_init(&callout_wait_lock, "callout_wait_lock", NULL, MTX_DEF); cv_init(&callout_wait, "callout_wait"); } /* * The callout mechanism is based on the work of Adam M. Costello and * George Varghese, published in a technical report entitled "Redesigning * the BSD Callout and Timer Facilities" and modified slightly for inclusion * in FreeBSD by Justin T. Gibbs. The original work on the data structures * used in this implementation was published by G. Varghese and T. Lauck in * the paper "Hashed and Hierarchical Timing Wheels: Data Structures for * the Efficient Implementation of a Timer Facility" in the Proceedings of * the 11th ACM Annual Symposium on Operating Systems Principles, * Austin, Texas Nov 1987. */ /* * Software (low priority) clock interrupt. * Run periodic events from timeout queue. */ void softclock(void *dummy) { struct callout *c; struct callout_tailq *bucket; int curticks; int steps; /* #steps since we last allowed interrupts */ int depth; int mpcalls; int mtxcalls; int gcalls; int wakeup_cookie; #ifdef DIAGNOSTIC struct bintime bt1, bt2; struct timespec ts2; static uint64_t maxdt = 36893488147419102LL; /* 2 msec */ static timeout_t *lastfunc; #endif #ifndef MAX_SOFTCLOCK_STEPS #define MAX_SOFTCLOCK_STEPS 100 /* Maximum allowed value of steps. */ #endif /* MAX_SOFTCLOCK_STEPS */ mpcalls = 0; mtxcalls = 0; gcalls = 0; depth = 0; steps = 0; mtx_lock_spin(&callout_lock); while (softticks != ticks) { softticks++; /* * softticks may be modified by hard clock, so cache * it while we work on a given bucket. */ curticks = softticks; bucket = &callwheel[curticks & callwheelmask]; c = TAILQ_FIRST(bucket); while (c) { depth++; if (c->c_time != curticks) { c = TAILQ_NEXT(c, c_links.tqe); ++steps; if (steps >= MAX_SOFTCLOCK_STEPS) { nextsoftcheck = c; /* Give interrupts a chance. */ mtx_unlock_spin(&callout_lock); ; /* nothing */ mtx_lock_spin(&callout_lock); c = nextsoftcheck; steps = 0; } } else { void (*c_func)(void *); void *c_arg; struct mtx *c_mtx; int c_flags; nextsoftcheck = TAILQ_NEXT(c, c_links.tqe); TAILQ_REMOVE(bucket, c, c_links.tqe); c_func = c->c_func; c_arg = c->c_arg; c_mtx = c->c_mtx; c_flags = c->c_flags; if (c->c_flags & CALLOUT_LOCAL_ALLOC) { c->c_func = NULL; c->c_flags = CALLOUT_LOCAL_ALLOC; SLIST_INSERT_HEAD(&callfree, c, c_links.sle); } else { c->c_flags = (c->c_flags & ~CALLOUT_PENDING); } curr_callout = c; curr_cancelled = 0; mtx_unlock_spin(&callout_lock); if (c_mtx != NULL) { mtx_lock(c_mtx); /* * The callout may have been cancelled * while we switched locks. */ if (curr_cancelled) { mtx_unlock(c_mtx); mtx_lock_spin(&callout_lock); goto done_locked; } /* The callout cannot be stopped now. */ curr_cancelled = 1; if (c_mtx == &Giant) { gcalls++; CTR1(KTR_CALLOUT, "callout %p", c_func); } else { mtxcalls++; CTR1(KTR_CALLOUT, "callout mtx %p", c_func); } } else { mpcalls++; CTR1(KTR_CALLOUT, "callout mpsafe %p", c_func); } #ifdef DIAGNOSTIC binuptime(&bt1); mtx_lock(&dont_sleep_in_callout); #endif c_func(c_arg); #ifdef DIAGNOSTIC mtx_unlock(&dont_sleep_in_callout); binuptime(&bt2); bintime_sub(&bt2, &bt1); if (bt2.frac > maxdt) { if (lastfunc != c_func || bt2.frac > maxdt * 2) { bintime2timespec(&bt2, &ts2); printf( "Expensive timeout(9) function: %p(%p) %jd.%09ld s\n", c_func, c_arg, (intmax_t)ts2.tv_sec, ts2.tv_nsec); } maxdt = bt2.frac; lastfunc = c_func; } #endif if ((c_flags & CALLOUT_RETURNUNLOCKED) == 0) mtx_unlock(c_mtx); mtx_lock_spin(&callout_lock); done_locked: curr_callout = NULL; if (wakeup_needed) { /* * There might be someone waiting * for the callout to complete. */ wakeup_cookie = wakeup_ctr; mtx_unlock_spin(&callout_lock); mtx_lock(&callout_wait_lock); cv_broadcast(&callout_wait); wakeup_done_ctr = wakeup_cookie; mtx_unlock(&callout_wait_lock); mtx_lock_spin(&callout_lock); wakeup_needed = 0; } steps = 0; c = nextsoftcheck; } } } avg_depth += (depth * 1000 - avg_depth) >> 8; avg_mpcalls += (mpcalls * 1000 - avg_mpcalls) >> 8; avg_mtxcalls += (mtxcalls * 1000 - avg_mtxcalls) >> 8; avg_gcalls += (gcalls * 1000 - avg_gcalls) >> 8; nextsoftcheck = NULL; mtx_unlock_spin(&callout_lock); } /* * timeout -- * Execute a function after a specified length of time. * * untimeout -- * Cancel previous timeout function call. * * callout_handle_init -- * Initialize a handle so that using it with untimeout is benign. * * See AT&T BCI Driver Reference Manual for specification. This * implementation differs from that one in that although an * identification value is returned from timeout, the original * arguments to timeout as well as the identifier are used to * identify entries for untimeout. */ struct callout_handle timeout(ftn, arg, to_ticks) timeout_t *ftn; void *arg; int to_ticks; { struct callout *new; struct callout_handle handle; mtx_lock_spin(&callout_lock); /* Fill in the next free callout structure. */ new = SLIST_FIRST(&callfree); if (new == NULL) /* XXX Attempt to malloc first */ panic("timeout table full"); SLIST_REMOVE_HEAD(&callfree, c_links.sle); callout_reset(new, to_ticks, ftn, arg); handle.callout = new; mtx_unlock_spin(&callout_lock); return (handle); } void untimeout(ftn, arg, handle) timeout_t *ftn; void *arg; struct callout_handle handle; { /* * Check for a handle that was initialized * by callout_handle_init, but never used * for a real timeout. */ if (handle.callout == NULL) return; mtx_lock_spin(&callout_lock); if (handle.callout->c_func == ftn && handle.callout->c_arg == arg) callout_stop(handle.callout); mtx_unlock_spin(&callout_lock); } void callout_handle_init(struct callout_handle *handle) { handle->callout = NULL; } /* * New interface; clients allocate their own callout structures. * * callout_reset() - establish or change a timeout * callout_stop() - disestablish a timeout * callout_init() - initialize a callout structure so that it can * safely be passed to callout_reset() and callout_stop() * * defines three convenience macros: * * callout_active() - returns truth if callout has not been stopped, * drained, or deactivated since the last time the callout was * reset. * callout_pending() - returns truth if callout is still waiting for timeout * callout_deactivate() - marks the callout as having been serviced */ void callout_reset(c, to_ticks, ftn, arg) struct callout *c; int to_ticks; void (*ftn)(void *); void *arg; { #ifdef notyet /* Some callers of timeout() do not hold Giant. */ if (c->c_mtx != NULL) mtx_assert(c->c_mtx, MA_OWNED); #endif mtx_lock_spin(&callout_lock); if (c == curr_callout) { /* * We're being asked to reschedule a callout which is * currently in progress. If there is a mutex then we * can cancel the callout if it has not really started. */ if (c->c_mtx != NULL && !curr_cancelled) curr_cancelled = 1; if (wakeup_needed) { /* * Someone has called callout_drain to kill this * callout. Don't reschedule. */ mtx_unlock_spin(&callout_lock); return; } } if (c->c_flags & CALLOUT_PENDING) { if (nextsoftcheck == c) { nextsoftcheck = TAILQ_NEXT(c, c_links.tqe); } TAILQ_REMOVE(&callwheel[c->c_time & callwheelmask], c, c_links.tqe); /* * Part of the normal "stop a pending callout" process * is to clear the CALLOUT_ACTIVE and CALLOUT_PENDING * flags. We're not going to bother doing that here, * because we're going to be setting those flags ten lines * after this point, and we're holding callout_lock * between now and then. */ } /* * We could unlock callout_lock here and lock it again before the * TAILQ_INSERT_TAIL, but there's no point since doing this setup * doesn't take much time. */ if (to_ticks <= 0) to_ticks = 1; c->c_arg = arg; c->c_flags |= (CALLOUT_ACTIVE | CALLOUT_PENDING); c->c_func = ftn; c->c_time = ticks + to_ticks; TAILQ_INSERT_TAIL(&callwheel[c->c_time & callwheelmask], c, c_links.tqe); mtx_unlock_spin(&callout_lock); } int _callout_stop_safe(c, safe) struct callout *c; int safe; { int use_mtx, wakeup_cookie; if (!safe && c->c_mtx != NULL) { #ifdef notyet /* Some callers do not hold Giant for Giant-locked callouts. */ mtx_assert(c->c_mtx, MA_OWNED); use_mtx = 1; #else use_mtx = mtx_owned(c->c_mtx); #endif } else { use_mtx = 0; } mtx_lock_spin(&callout_lock); /* * Don't attempt to delete a callout that's not on the queue. */ if (!(c->c_flags & CALLOUT_PENDING)) { c->c_flags &= ~CALLOUT_ACTIVE; if (c != curr_callout) { mtx_unlock_spin(&callout_lock); return (0); } if (safe) { /* We need to wait until the callout is finished. */ wakeup_needed = 1; wakeup_cookie = wakeup_ctr++; mtx_unlock_spin(&callout_lock); mtx_lock(&callout_wait_lock); /* * Check to make sure that softclock() didn't * do the wakeup in between our dropping * callout_lock and picking up callout_wait_lock */ if (wakeup_cookie - wakeup_done_ctr > 0) cv_wait(&callout_wait, &callout_wait_lock); mtx_unlock(&callout_wait_lock); } else if (use_mtx && !curr_cancelled) { /* We can stop the callout before it runs. */ curr_cancelled = 1; mtx_unlock_spin(&callout_lock); return (1); } else mtx_unlock_spin(&callout_lock); return (0); } c->c_flags &= ~(CALLOUT_ACTIVE | CALLOUT_PENDING); if (nextsoftcheck == c) { nextsoftcheck = TAILQ_NEXT(c, c_links.tqe); } TAILQ_REMOVE(&callwheel[c->c_time & callwheelmask], c, c_links.tqe); if (c->c_flags & CALLOUT_LOCAL_ALLOC) { c->c_func = NULL; SLIST_INSERT_HEAD(&callfree, c, c_links.sle); } mtx_unlock_spin(&callout_lock); return (1); } void callout_init(c, mpsafe) struct callout *c; int mpsafe; { bzero(c, sizeof *c); if (mpsafe) { c->c_mtx = NULL; c->c_flags = CALLOUT_RETURNUNLOCKED; } else { c->c_mtx = &Giant; c->c_flags = 0; } } void callout_init_mtx(c, mtx, flags) struct callout *c; struct mtx *mtx; int flags; { bzero(c, sizeof *c); c->c_mtx = mtx; KASSERT((flags & ~CALLOUT_RETURNUNLOCKED) == 0, ("callout_init_mtx: bad flags %d", flags)); /* CALLOUT_RETURNUNLOCKED makes no sense without a mutex. */ KASSERT(mtx != NULL || (flags & CALLOUT_RETURNUNLOCKED) == 0, ("callout_init_mtx: CALLOUT_RETURNUNLOCKED with no mutex")); c->c_flags = flags & CALLOUT_RETURNUNLOCKED; } #ifdef APM_FIXUP_CALLTODO /* * Adjust the kernel calltodo timeout list. This routine is used after * an APM resume to recalculate the calltodo timer list values with the * number of hz's we have been sleeping. The next hardclock() will detect * that there are fired timers and run softclock() to execute them. * * Please note, I have not done an exhaustive analysis of what code this * might break. I am motivated to have my select()'s and alarm()'s that * have expired during suspend firing upon resume so that the applications * which set the timer can do the maintanence the timer was for as close * as possible to the originally intended time. Testing this code for a * week showed that resuming from a suspend resulted in 22 to 25 timers * firing, which seemed independant on whether the suspend was 2 hours or * 2 days. Your milage may vary. - Ken Key */ void adjust_timeout_calltodo(time_change) struct timeval *time_change; { register struct callout *p; unsigned long delta_ticks; /* * How many ticks were we asleep? * (stolen from tvtohz()). */ /* Don't do anything */ if (time_change->tv_sec < 0) return; else if (time_change->tv_sec <= LONG_MAX / 1000000) delta_ticks = (time_change->tv_sec * 1000000 + time_change->tv_usec + (tick - 1)) / tick + 1; else if (time_change->tv_sec <= LONG_MAX / hz) delta_ticks = time_change->tv_sec * hz + (time_change->tv_usec + (tick - 1)) / tick + 1; else delta_ticks = LONG_MAX; if (delta_ticks > INT_MAX) delta_ticks = INT_MAX; /* * Now rip through the timer calltodo list looking for timers * to expire. */ /* don't collide with softclock() */ mtx_lock_spin(&callout_lock); for (p = calltodo.c_next; p != NULL; p = p->c_next) { p->c_time -= delta_ticks; /* Break if the timer had more time on it than delta_ticks */ if (p->c_time > 0) break; /* take back the ticks the timer didn't use (p->c_time <= 0) */ delta_ticks = -p->c_time; } mtx_unlock_spin(&callout_lock); return; } #endif /* APM_FIXUP_CALLTODO */