kern_timeout.c revision 115810
11541Srgrimes/*- 21541Srgrimes * Copyright (c) 1982, 1986, 1991, 1993 31541Srgrimes * The Regents of the University of California. All rights reserved. 41541Srgrimes * (c) UNIX System Laboratories, Inc. 51541Srgrimes * All or some portions of this file are derived from material licensed 61541Srgrimes * to the University of California by American Telephone and Telegraph 71541Srgrimes * Co. or Unix System Laboratories, Inc. and are reproduced herein with 81541Srgrimes * the permission of UNIX System Laboratories, Inc. 91541Srgrimes * 101541Srgrimes * Redistribution and use in source and binary forms, with or without 111541Srgrimes * modification, are permitted provided that the following conditions 121541Srgrimes * are met: 131541Srgrimes * 1. Redistributions of source code must retain the above copyright 141541Srgrimes * notice, this list of conditions and the following disclaimer. 151541Srgrimes * 2. Redistributions in binary form must reproduce the above copyright 161541Srgrimes * notice, this list of conditions and the following disclaimer in the 171541Srgrimes * documentation and/or other materials provided with the distribution. 181541Srgrimes * 3. All advertising materials mentioning features or use of this software 191541Srgrimes * must display the following acknowledgement: 201541Srgrimes * This product includes software developed by the University of 211541Srgrimes * California, Berkeley and its contributors. 221541Srgrimes * 4. Neither the name of the University nor the names of its contributors 231541Srgrimes * may be used to endorse or promote products derived from this software 241541Srgrimes * without specific prior written permission. 251541Srgrimes * 261541Srgrimes * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 271541Srgrimes * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 281541Srgrimes * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 291541Srgrimes * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 301541Srgrimes * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 311541Srgrimes * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 321541Srgrimes * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 331541Srgrimes * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 341541Srgrimes * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 351541Srgrimes * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 361541Srgrimes * SUCH DAMAGE. 371541Srgrimes * 3844510Swollman * From: @(#)kern_clock.c 8.5 (Berkeley) 1/21/94 3950477Speter * $FreeBSD: head/sys/kern/kern_timeout.c 115810 2003-06-04 05:25:58Z phk $ 401541Srgrimes */ 411541Srgrimes 421541Srgrimes#include <sys/param.h> 431541Srgrimes#include <sys/systm.h> 4433392Sphk#include <sys/callout.h> 451541Srgrimes#include <sys/kernel.h> 4674914Sjhb#include <sys/lock.h> 4768840Sjhb#include <sys/mutex.h> 48115810Sphk#include <sys/sysctl.h> 491541Srgrimes 50115810Sphkstatic int avg_depth; 51115810SphkSYSCTL_INT(_debug, OID_AUTO, to_avg_depth, CTLFLAG_RD, &avg_depth, 0, 52115810Sphk "Average number of items examined per softclock call. Units = 1/1000"); 53115810Sphkstatic int avg_gcalls; 54115810SphkSYSCTL_INT(_debug, OID_AUTO, to_avg_gcalls, CTLFLAG_RD, &avg_gcalls, 0, 55115810Sphk "Average number of Giant callouts made per softclock call. Units = 1/1000"); 56115810Sphkstatic int avg_mpcalls; 57115810SphkSYSCTL_INT(_debug, OID_AUTO, to_avg_mpcalls, CTLFLAG_RD, &avg_mpcalls, 0, 58115810Sphk "Average number of MP callouts made per softclock call. Units = 1/1000"); 5933392Sphk/* 6033392Sphk * TODO: 6133392Sphk * allocate more timeout table slots when table overflows. 6233392Sphk */ 6333392Sphk 6433392Sphk/* Exported to machdep.c and/or kern_clock.c. */ 6529680Sgibbsstruct callout *callout; 6629680Sgibbsstruct callout_list callfree; 6729680Sgibbsint callwheelsize, callwheelbits, callwheelmask; 6829680Sgibbsstruct callout_tailq *callwheel; 6933392Sphkint softticks; /* Like ticks, but for softclock(). */ 7068889Sjakestruct mtx callout_lock; 712112Swollman 7229680Sgibbsstatic struct callout *nextsoftcheck; /* Next callout to be checked. */ 731541Srgrimes 741541Srgrimes/* 7582127Sdillon * kern_timeout_callwheel_alloc() - kernel low level callwheel initialization 7682127Sdillon * 7782127Sdillon * This code is called very early in the kernel initialization sequence, 7882127Sdillon * and may be called more then once. 7982127Sdillon */ 8082127Sdilloncaddr_t 8182127Sdillonkern_timeout_callwheel_alloc(caddr_t v) 8282127Sdillon{ 8382127Sdillon /* 8482127Sdillon * Calculate callout wheel size 8582127Sdillon */ 8682127Sdillon for (callwheelsize = 1, callwheelbits = 0; 8782127Sdillon callwheelsize < ncallout; 8882127Sdillon callwheelsize <<= 1, ++callwheelbits) 8982127Sdillon ; 9082127Sdillon callwheelmask = callwheelsize - 1; 9182127Sdillon 9282127Sdillon callout = (struct callout *)v; 9382127Sdillon v = (caddr_t)(callout + ncallout); 9482127Sdillon callwheel = (struct callout_tailq *)v; 9582127Sdillon v = (caddr_t)(callwheel + callwheelsize); 9682127Sdillon return(v); 9782127Sdillon} 9882127Sdillon 9982127Sdillon/* 10082127Sdillon * kern_timeout_callwheel_init() - initialize previously reserved callwheel 10182127Sdillon * space. 10282127Sdillon * 10382127Sdillon * This code is called just once, after the space reserved for the 10482127Sdillon * callout wheel has been finalized. 10582127Sdillon */ 10682127Sdillonvoid 10782127Sdillonkern_timeout_callwheel_init(void) 10882127Sdillon{ 10982127Sdillon int i; 11082127Sdillon 11182127Sdillon SLIST_INIT(&callfree); 11282127Sdillon for (i = 0; i < ncallout; i++) { 11382127Sdillon callout_init(&callout[i], 0); 11482127Sdillon callout[i].c_flags = CALLOUT_LOCAL_ALLOC; 11582127Sdillon SLIST_INSERT_HEAD(&callfree, &callout[i], c_links.sle); 11682127Sdillon } 11782127Sdillon for (i = 0; i < callwheelsize; i++) { 11882127Sdillon TAILQ_INIT(&callwheel[i]); 11982127Sdillon } 12093818Sjhb mtx_init(&callout_lock, "callout", NULL, MTX_SPIN | MTX_RECURSE); 12182127Sdillon} 12282127Sdillon 12382127Sdillon/* 12429680Sgibbs * The callout mechanism is based on the work of Adam M. Costello and 12529680Sgibbs * George Varghese, published in a technical report entitled "Redesigning 12629680Sgibbs * the BSD Callout and Timer Facilities" and modified slightly for inclusion 12729680Sgibbs * in FreeBSD by Justin T. Gibbs. The original work on the data structures 12829680Sgibbs * used in this implementation was published by G.Varghese and A. Lauck in 12929680Sgibbs * the paper "Hashed and Hierarchical Timing Wheels: Data Structures for 13029680Sgibbs * the Efficient Implementation of a Timer Facility" in the Proceedings of 13129680Sgibbs * the 11th ACM Annual Symposium on Operating Systems Principles, 13229680Sgibbs * Austin, Texas Nov 1987. 13329680Sgibbs */ 13432388Sphk 13529680Sgibbs/* 1361541Srgrimes * Software (low priority) clock interrupt. 1371541Srgrimes * Run periodic events from timeout queue. 1381541Srgrimes */ 1391541Srgrimesvoid 14067551Sjhbsoftclock(void *dummy) 1411541Srgrimes{ 142102936Sphk struct callout *c; 143102936Sphk struct callout_tailq *bucket; 144102936Sphk int curticks; 145102936Sphk int steps; /* #steps since we last allowed interrupts */ 146115810Sphk int depth; 147115810Sphk int mpcalls; 148115810Sphk int gcalls; 149102936Sphk#ifdef DIAGNOSTIC 150102936Sphk struct bintime bt1, bt2; 151102936Sphk struct timespec ts2; 152102936Sphk static uint64_t maxdt = 18446744073709551LL; /* 1 msec */ 153102936Sphk#endif 1541541Srgrimes 15533392Sphk#ifndef MAX_SOFTCLOCK_STEPS 15633392Sphk#define MAX_SOFTCLOCK_STEPS 100 /* Maximum allowed value of steps. */ 15733392Sphk#endif /* MAX_SOFTCLOCK_STEPS */ 15829680Sgibbs 159115810Sphk mpcalls = 0; 160115810Sphk gcalls = 0; 161115810Sphk depth = 0; 16229680Sgibbs steps = 0; 16372200Sbmilekic mtx_lock_spin(&callout_lock); 16429680Sgibbs while (softticks != ticks) { 16529805Sgibbs softticks++; 16629805Sgibbs /* 16729805Sgibbs * softticks may be modified by hard clock, so cache 16829805Sgibbs * it while we work on a given bucket. 16929805Sgibbs */ 17029805Sgibbs curticks = softticks; 17129805Sgibbs bucket = &callwheel[curticks & callwheelmask]; 17229805Sgibbs c = TAILQ_FIRST(bucket); 17329680Sgibbs while (c) { 174115810Sphk depth++; 17529805Sgibbs if (c->c_time != curticks) { 17629680Sgibbs c = TAILQ_NEXT(c, c_links.tqe); 17729680Sgibbs ++steps; 17829680Sgibbs if (steps >= MAX_SOFTCLOCK_STEPS) { 17929680Sgibbs nextsoftcheck = c; 18029805Sgibbs /* Give interrupts a chance. */ 18172200Sbmilekic mtx_unlock_spin(&callout_lock); 18281370Sjhb ; /* nothing */ 18372200Sbmilekic mtx_lock_spin(&callout_lock); 18429680Sgibbs c = nextsoftcheck; 18529680Sgibbs steps = 0; 18629680Sgibbs } 18729680Sgibbs } else { 18829680Sgibbs void (*c_func)(void *); 18929680Sgibbs void *c_arg; 19068889Sjake int c_flags; 19129680Sgibbs 19229680Sgibbs nextsoftcheck = TAILQ_NEXT(c, c_links.tqe); 19329805Sgibbs TAILQ_REMOVE(bucket, c, c_links.tqe); 19429680Sgibbs c_func = c->c_func; 19529680Sgibbs c_arg = c->c_arg; 19668889Sjake c_flags = c->c_flags; 19729680Sgibbs c->c_func = NULL; 19844510Swollman if (c->c_flags & CALLOUT_LOCAL_ALLOC) { 19944510Swollman c->c_flags = CALLOUT_LOCAL_ALLOC; 20044510Swollman SLIST_INSERT_HEAD(&callfree, c, 20144510Swollman c_links.sle); 20244510Swollman } else { 20344510Swollman c->c_flags = 20450673Sjlemon (c->c_flags & ~CALLOUT_PENDING); 20544510Swollman } 20672200Sbmilekic mtx_unlock_spin(&callout_lock); 207115810Sphk if (!(c_flags & CALLOUT_MPSAFE)) { 20872200Sbmilekic mtx_lock(&Giant); 209115810Sphk gcalls++; 210115810Sphk } else { 211115810Sphk mpcalls++; 212115810Sphk } 213102936Sphk#ifdef DIAGNOSTIC 214102936Sphk binuptime(&bt1); 215102936Sphk#endif 21629680Sgibbs c_func(c_arg); 217102936Sphk#ifdef DIAGNOSTIC 218102936Sphk binuptime(&bt2); 219102936Sphk bintime_sub(&bt2, &bt1); 220102936Sphk if (bt2.frac > maxdt) { 221110185Sphk maxdt = bt2.frac; 222102936Sphk bintime2timespec(&bt2, &ts2); 223102936Sphk printf( 224110185Sphk "Expensive timeout(9) function: %p(%p) %d.%09ld s\n", 225102936Sphk c_func, c_arg, 226102936Sphk ts2.tv_sec, ts2.tv_nsec); 227102936Sphk } 228102936Sphk#endif 22968889Sjake if (!(c_flags & CALLOUT_MPSAFE)) 23072200Sbmilekic mtx_unlock(&Giant); 23172200Sbmilekic mtx_lock_spin(&callout_lock); 23229680Sgibbs steps = 0; 23329680Sgibbs c = nextsoftcheck; 23429680Sgibbs } 23529680Sgibbs } 2361541Srgrimes } 237115810Sphk avg_depth += (depth * 1000 - avg_depth) >> 8; 238115810Sphk avg_mpcalls += (mpcalls * 1000 - avg_mpcalls) >> 8; 239115810Sphk avg_gcalls += (gcalls * 1000 - avg_gcalls) >> 8; 24029680Sgibbs nextsoftcheck = NULL; 24172200Sbmilekic mtx_unlock_spin(&callout_lock); 2421541Srgrimes} 2431541Srgrimes 2441541Srgrimes/* 2451541Srgrimes * timeout -- 2461541Srgrimes * Execute a function after a specified length of time. 2471541Srgrimes * 2481541Srgrimes * untimeout -- 2491541Srgrimes * Cancel previous timeout function call. 2501541Srgrimes * 25129680Sgibbs * callout_handle_init -- 25229680Sgibbs * Initialize a handle so that using it with untimeout is benign. 25329680Sgibbs * 2541541Srgrimes * See AT&T BCI Driver Reference Manual for specification. This 25529680Sgibbs * implementation differs from that one in that although an 25629680Sgibbs * identification value is returned from timeout, the original 25729680Sgibbs * arguments to timeout as well as the identifier are used to 25829680Sgibbs * identify entries for untimeout. 2591541Srgrimes */ 26029680Sgibbsstruct callout_handle 26129680Sgibbstimeout(ftn, arg, to_ticks) 26233824Sbde timeout_t *ftn; 2631541Srgrimes void *arg; 26469147Sjlemon int to_ticks; 2651541Srgrimes{ 26629680Sgibbs struct callout *new; 26729680Sgibbs struct callout_handle handle; 2681541Srgrimes 26972200Sbmilekic mtx_lock_spin(&callout_lock); 2701541Srgrimes 2711541Srgrimes /* Fill in the next free callout structure. */ 27229680Sgibbs new = SLIST_FIRST(&callfree); 27329680Sgibbs if (new == NULL) 27429680Sgibbs /* XXX Attempt to malloc first */ 2751541Srgrimes panic("timeout table full"); 27629680Sgibbs SLIST_REMOVE_HEAD(&callfree, c_links.sle); 27744510Swollman 27844510Swollman callout_reset(new, to_ticks, ftn, arg); 2791541Srgrimes 28044510Swollman handle.callout = new; 28172200Sbmilekic mtx_unlock_spin(&callout_lock); 28229680Sgibbs return (handle); 2831541Srgrimes} 2841541Srgrimes 2851541Srgrimesvoid 28629680Sgibbsuntimeout(ftn, arg, handle) 28733824Sbde timeout_t *ftn; 2881541Srgrimes void *arg; 28929680Sgibbs struct callout_handle handle; 2901541Srgrimes{ 2911541Srgrimes 29229680Sgibbs /* 29329680Sgibbs * Check for a handle that was initialized 29429680Sgibbs * by callout_handle_init, but never used 29529680Sgibbs * for a real timeout. 29629680Sgibbs */ 29729680Sgibbs if (handle.callout == NULL) 29829680Sgibbs return; 29929680Sgibbs 30072200Sbmilekic mtx_lock_spin(&callout_lock); 30144510Swollman if (handle.callout->c_func == ftn && handle.callout->c_arg == arg) 30244510Swollman callout_stop(handle.callout); 30372200Sbmilekic mtx_unlock_spin(&callout_lock); 3041541Srgrimes} 3051541Srgrimes 30624101Sbdevoid 30729680Sgibbscallout_handle_init(struct callout_handle *handle) 30829680Sgibbs{ 30929680Sgibbs handle->callout = NULL; 31029680Sgibbs} 31129680Sgibbs 31244510Swollman/* 31344510Swollman * New interface; clients allocate their own callout structures. 31444510Swollman * 31544510Swollman * callout_reset() - establish or change a timeout 31644510Swollman * callout_stop() - disestablish a timeout 31744510Swollman * callout_init() - initialize a callout structure so that it can 31844510Swollman * safely be passed to callout_reset() and callout_stop() 31944510Swollman * 32050673Sjlemon * <sys/callout.h> defines three convenience macros: 32144510Swollman * 32250673Sjlemon * callout_active() - returns truth if callout has not been serviced 32350673Sjlemon * callout_pending() - returns truth if callout is still waiting for timeout 32450673Sjlemon * callout_deactivate() - marks the callout as having been serviced 32544510Swollman */ 32644510Swollmanvoid 32769147Sjlemoncallout_reset(c, to_ticks, ftn, arg) 32844510Swollman struct callout *c; 32944510Swollman int to_ticks; 33092723Salfred void (*ftn)(void *); 33144510Swollman void *arg; 33244510Swollman{ 33344510Swollman 33472200Sbmilekic mtx_lock_spin(&callout_lock); 33544510Swollman if (c->c_flags & CALLOUT_PENDING) 33644510Swollman callout_stop(c); 33744510Swollman 33844510Swollman /* 33981370Sjhb * We could unlock callout_lock here and lock it again before the 34081370Sjhb * TAILQ_INSERT_TAIL, but there's no point since doing this setup 34181370Sjhb * doesn't take much time. 34244510Swollman */ 34344510Swollman if (to_ticks <= 0) 34444510Swollman to_ticks = 1; 34544510Swollman 34644510Swollman c->c_arg = arg; 34769147Sjlemon c->c_flags |= (CALLOUT_ACTIVE | CALLOUT_PENDING); 34844510Swollman c->c_func = ftn; 34944510Swollman c->c_time = ticks + to_ticks; 35044510Swollman TAILQ_INSERT_TAIL(&callwheel[c->c_time & callwheelmask], 35144510Swollman c, c_links.tqe); 35272200Sbmilekic mtx_unlock_spin(&callout_lock); 35344510Swollman} 35444510Swollman 35581481Sjhbint 35644510Swollmancallout_stop(c) 35744510Swollman struct callout *c; 35844510Swollman{ 35944510Swollman 36072200Sbmilekic mtx_lock_spin(&callout_lock); 36144510Swollman /* 36244510Swollman * Don't attempt to delete a callout that's not on the queue. 36344510Swollman */ 36444510Swollman if (!(c->c_flags & CALLOUT_PENDING)) { 36550673Sjlemon c->c_flags &= ~CALLOUT_ACTIVE; 36672200Sbmilekic mtx_unlock_spin(&callout_lock); 36781481Sjhb return (0); 36844510Swollman } 36950673Sjlemon c->c_flags &= ~(CALLOUT_ACTIVE | CALLOUT_PENDING); 37044510Swollman 37144510Swollman if (nextsoftcheck == c) { 37244510Swollman nextsoftcheck = TAILQ_NEXT(c, c_links.tqe); 37344510Swollman } 37444510Swollman TAILQ_REMOVE(&callwheel[c->c_time & callwheelmask], c, c_links.tqe); 37544510Swollman c->c_func = NULL; 37644510Swollman 37744510Swollman if (c->c_flags & CALLOUT_LOCAL_ALLOC) { 37844510Swollman SLIST_INSERT_HEAD(&callfree, c, c_links.sle); 37944510Swollman } 38072200Sbmilekic mtx_unlock_spin(&callout_lock); 38181481Sjhb return (1); 38244510Swollman} 38344510Swollman 38444510Swollmanvoid 38569147Sjlemoncallout_init(c, mpsafe) 38644510Swollman struct callout *c; 38769147Sjlemon int mpsafe; 38844510Swollman{ 38944527Swollman bzero(c, sizeof *c); 39069147Sjlemon if (mpsafe) 39169147Sjlemon c->c_flags |= CALLOUT_MPSAFE; 39244510Swollman} 39344510Swollman 39431950Snate#ifdef APM_FIXUP_CALLTODO 39531950Snate/* 39631950Snate * Adjust the kernel calltodo timeout list. This routine is used after 39731950Snate * an APM resume to recalculate the calltodo timer list values with the 39831950Snate * number of hz's we have been sleeping. The next hardclock() will detect 39931950Snate * that there are fired timers and run softclock() to execute them. 40031950Snate * 40131950Snate * Please note, I have not done an exhaustive analysis of what code this 40231950Snate * might break. I am motivated to have my select()'s and alarm()'s that 40331950Snate * have expired during suspend firing upon resume so that the applications 40431950Snate * which set the timer can do the maintanence the timer was for as close 40531950Snate * as possible to the originally intended time. Testing this code for a 40631950Snate * week showed that resuming from a suspend resulted in 22 to 25 timers 40731950Snate * firing, which seemed independant on whether the suspend was 2 hours or 40831950Snate * 2 days. Your milage may vary. - Ken Key <key@cs.utk.edu> 40931950Snate */ 41031950Snatevoid 41131950Snateadjust_timeout_calltodo(time_change) 41231950Snate struct timeval *time_change; 41331950Snate{ 41431950Snate register struct callout *p; 41531950Snate unsigned long delta_ticks; 41631950Snate 41731950Snate /* 41831950Snate * How many ticks were we asleep? 41936127Sbde * (stolen from tvtohz()). 42031950Snate */ 42131950Snate 42231950Snate /* Don't do anything */ 42331950Snate if (time_change->tv_sec < 0) 42431950Snate return; 42531950Snate else if (time_change->tv_sec <= LONG_MAX / 1000000) 42631950Snate delta_ticks = (time_change->tv_sec * 1000000 + 42731950Snate time_change->tv_usec + (tick - 1)) / tick + 1; 42831950Snate else if (time_change->tv_sec <= LONG_MAX / hz) 42931950Snate delta_ticks = time_change->tv_sec * hz + 43031950Snate (time_change->tv_usec + (tick - 1)) / tick + 1; 43131950Snate else 43231950Snate delta_ticks = LONG_MAX; 43331950Snate 43431950Snate if (delta_ticks > INT_MAX) 43531950Snate delta_ticks = INT_MAX; 43631950Snate 43731950Snate /* 43831950Snate * Now rip through the timer calltodo list looking for timers 43931950Snate * to expire. 44031950Snate */ 44131950Snate 44231950Snate /* don't collide with softclock() */ 44372200Sbmilekic mtx_lock_spin(&callout_lock); 44431950Snate for (p = calltodo.c_next; p != NULL; p = p->c_next) { 44531950Snate p->c_time -= delta_ticks; 44631950Snate 44731950Snate /* Break if the timer had more time on it than delta_ticks */ 44831950Snate if (p->c_time > 0) 44931950Snate break; 45031950Snate 45131950Snate /* take back the ticks the timer didn't use (p->c_time <= 0) */ 45231950Snate delta_ticks = -p->c_time; 45331950Snate } 45472200Sbmilekic mtx_unlock_spin(&callout_lock); 45531950Snate 45631950Snate return; 45731950Snate} 45831950Snate#endif /* APM_FIXUP_CALLTODO */ 459