kern_timeout.c revision 102936
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 102936 2002-09-04 20:05:00Z 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> 481541Srgrimes 4933392Sphk/* 5033392Sphk * TODO: 5133392Sphk * allocate more timeout table slots when table overflows. 5233392Sphk */ 5333392Sphk 5433392Sphk/* Exported to machdep.c and/or kern_clock.c. */ 5529680Sgibbsstruct callout *callout; 5629680Sgibbsstruct callout_list callfree; 5729680Sgibbsint callwheelsize, callwheelbits, callwheelmask; 5829680Sgibbsstruct callout_tailq *callwheel; 5933392Sphkint softticks; /* Like ticks, but for softclock(). */ 6068889Sjakestruct mtx callout_lock; 612112Swollman 6229680Sgibbsstatic struct callout *nextsoftcheck; /* Next callout to be checked. */ 631541Srgrimes 641541Srgrimes/* 6582127Sdillon * kern_timeout_callwheel_alloc() - kernel low level callwheel initialization 6682127Sdillon * 6782127Sdillon * This code is called very early in the kernel initialization sequence, 6882127Sdillon * and may be called more then once. 6982127Sdillon */ 7082127Sdilloncaddr_t 7182127Sdillonkern_timeout_callwheel_alloc(caddr_t v) 7282127Sdillon{ 7382127Sdillon /* 7482127Sdillon * Calculate callout wheel size 7582127Sdillon */ 7682127Sdillon for (callwheelsize = 1, callwheelbits = 0; 7782127Sdillon callwheelsize < ncallout; 7882127Sdillon callwheelsize <<= 1, ++callwheelbits) 7982127Sdillon ; 8082127Sdillon callwheelmask = callwheelsize - 1; 8182127Sdillon 8282127Sdillon callout = (struct callout *)v; 8382127Sdillon v = (caddr_t)(callout + ncallout); 8482127Sdillon callwheel = (struct callout_tailq *)v; 8582127Sdillon v = (caddr_t)(callwheel + callwheelsize); 8682127Sdillon return(v); 8782127Sdillon} 8882127Sdillon 8982127Sdillon/* 9082127Sdillon * kern_timeout_callwheel_init() - initialize previously reserved callwheel 9182127Sdillon * space. 9282127Sdillon * 9382127Sdillon * This code is called just once, after the space reserved for the 9482127Sdillon * callout wheel has been finalized. 9582127Sdillon */ 9682127Sdillonvoid 9782127Sdillonkern_timeout_callwheel_init(void) 9882127Sdillon{ 9982127Sdillon int i; 10082127Sdillon 10182127Sdillon SLIST_INIT(&callfree); 10282127Sdillon for (i = 0; i < ncallout; i++) { 10382127Sdillon callout_init(&callout[i], 0); 10482127Sdillon callout[i].c_flags = CALLOUT_LOCAL_ALLOC; 10582127Sdillon SLIST_INSERT_HEAD(&callfree, &callout[i], c_links.sle); 10682127Sdillon } 10782127Sdillon for (i = 0; i < callwheelsize; i++) { 10882127Sdillon TAILQ_INIT(&callwheel[i]); 10982127Sdillon } 11093818Sjhb mtx_init(&callout_lock, "callout", NULL, MTX_SPIN | MTX_RECURSE); 11182127Sdillon} 11282127Sdillon 11382127Sdillon/* 11429680Sgibbs * The callout mechanism is based on the work of Adam M. Costello and 11529680Sgibbs * George Varghese, published in a technical report entitled "Redesigning 11629680Sgibbs * the BSD Callout and Timer Facilities" and modified slightly for inclusion 11729680Sgibbs * in FreeBSD by Justin T. Gibbs. The original work on the data structures 11829680Sgibbs * used in this implementation was published by G.Varghese and A. Lauck in 11929680Sgibbs * the paper "Hashed and Hierarchical Timing Wheels: Data Structures for 12029680Sgibbs * the Efficient Implementation of a Timer Facility" in the Proceedings of 12129680Sgibbs * the 11th ACM Annual Symposium on Operating Systems Principles, 12229680Sgibbs * Austin, Texas Nov 1987. 12329680Sgibbs */ 12432388Sphk 12529680Sgibbs/* 1261541Srgrimes * Software (low priority) clock interrupt. 1271541Srgrimes * Run periodic events from timeout queue. 1281541Srgrimes */ 1291541Srgrimesvoid 13067551Sjhbsoftclock(void *dummy) 1311541Srgrimes{ 132102936Sphk struct callout *c; 133102936Sphk struct callout_tailq *bucket; 134102936Sphk int curticks; 135102936Sphk int steps; /* #steps since we last allowed interrupts */ 136102936Sphk#ifdef DIAGNOSTIC 137102936Sphk struct bintime bt1, bt2; 138102936Sphk struct timespec ts2; 139102936Sphk static uint64_t maxdt = 18446744073709551LL; /* 1 msec */ 140102936Sphk#endif 1411541Srgrimes 14233392Sphk#ifndef MAX_SOFTCLOCK_STEPS 14333392Sphk#define MAX_SOFTCLOCK_STEPS 100 /* Maximum allowed value of steps. */ 14433392Sphk#endif /* MAX_SOFTCLOCK_STEPS */ 14529680Sgibbs 14629680Sgibbs steps = 0; 14772200Sbmilekic mtx_lock_spin(&callout_lock); 14829680Sgibbs while (softticks != ticks) { 14929805Sgibbs softticks++; 15029805Sgibbs /* 15129805Sgibbs * softticks may be modified by hard clock, so cache 15229805Sgibbs * it while we work on a given bucket. 15329805Sgibbs */ 15429805Sgibbs curticks = softticks; 15529805Sgibbs bucket = &callwheel[curticks & callwheelmask]; 15629805Sgibbs c = TAILQ_FIRST(bucket); 15729680Sgibbs while (c) { 15829805Sgibbs if (c->c_time != curticks) { 15929680Sgibbs c = TAILQ_NEXT(c, c_links.tqe); 16029680Sgibbs ++steps; 16129680Sgibbs if (steps >= MAX_SOFTCLOCK_STEPS) { 16229680Sgibbs nextsoftcheck = c; 16329805Sgibbs /* Give interrupts a chance. */ 16472200Sbmilekic mtx_unlock_spin(&callout_lock); 16581370Sjhb ; /* nothing */ 16672200Sbmilekic mtx_lock_spin(&callout_lock); 16729680Sgibbs c = nextsoftcheck; 16829680Sgibbs steps = 0; 16929680Sgibbs } 17029680Sgibbs } else { 17129680Sgibbs void (*c_func)(void *); 17229680Sgibbs void *c_arg; 17368889Sjake int c_flags; 17429680Sgibbs 17529680Sgibbs nextsoftcheck = TAILQ_NEXT(c, c_links.tqe); 17629805Sgibbs TAILQ_REMOVE(bucket, c, c_links.tqe); 17729680Sgibbs c_func = c->c_func; 17829680Sgibbs c_arg = c->c_arg; 17968889Sjake c_flags = c->c_flags; 18029680Sgibbs c->c_func = NULL; 18144510Swollman if (c->c_flags & CALLOUT_LOCAL_ALLOC) { 18244510Swollman c->c_flags = CALLOUT_LOCAL_ALLOC; 18344510Swollman SLIST_INSERT_HEAD(&callfree, c, 18444510Swollman c_links.sle); 18544510Swollman } else { 18644510Swollman c->c_flags = 18750673Sjlemon (c->c_flags & ~CALLOUT_PENDING); 18844510Swollman } 18972200Sbmilekic mtx_unlock_spin(&callout_lock); 19068889Sjake if (!(c_flags & CALLOUT_MPSAFE)) 19172200Sbmilekic mtx_lock(&Giant); 192102936Sphk#ifdef DIAGNOSTIC 193102936Sphk binuptime(&bt1); 194102936Sphk#endif 19529680Sgibbs c_func(c_arg); 196102936Sphk#ifdef DIAGNOSTIC 197102936Sphk binuptime(&bt2); 198102936Sphk bintime_sub(&bt2, &bt1); 199102936Sphk if (bt2.frac > maxdt) { 200102936Sphk bintime2timespec(&bt2, &ts2); 201102936Sphk printf( 202102936Sphk "Expensive timeout(9) function: %p(%p) %d.%09d\n", 203102936Sphk c_func, c_arg, 204102936Sphk ts2.tv_sec, ts2.tv_nsec); 205102936Sphk } 206102936Sphk#endif 20768889Sjake if (!(c_flags & CALLOUT_MPSAFE)) 20872200Sbmilekic mtx_unlock(&Giant); 20972200Sbmilekic mtx_lock_spin(&callout_lock); 21029680Sgibbs steps = 0; 21129680Sgibbs c = nextsoftcheck; 21229680Sgibbs } 21329680Sgibbs } 2141541Srgrimes } 21529680Sgibbs nextsoftcheck = NULL; 21672200Sbmilekic mtx_unlock_spin(&callout_lock); 2171541Srgrimes} 2181541Srgrimes 2191541Srgrimes/* 2201541Srgrimes * timeout -- 2211541Srgrimes * Execute a function after a specified length of time. 2221541Srgrimes * 2231541Srgrimes * untimeout -- 2241541Srgrimes * Cancel previous timeout function call. 2251541Srgrimes * 22629680Sgibbs * callout_handle_init -- 22729680Sgibbs * Initialize a handle so that using it with untimeout is benign. 22829680Sgibbs * 2291541Srgrimes * See AT&T BCI Driver Reference Manual for specification. This 23029680Sgibbs * implementation differs from that one in that although an 23129680Sgibbs * identification value is returned from timeout, the original 23229680Sgibbs * arguments to timeout as well as the identifier are used to 23329680Sgibbs * identify entries for untimeout. 2341541Srgrimes */ 23529680Sgibbsstruct callout_handle 23629680Sgibbstimeout(ftn, arg, to_ticks) 23733824Sbde timeout_t *ftn; 2381541Srgrimes void *arg; 23969147Sjlemon int to_ticks; 2401541Srgrimes{ 24129680Sgibbs struct callout *new; 24229680Sgibbs struct callout_handle handle; 2431541Srgrimes 24472200Sbmilekic mtx_lock_spin(&callout_lock); 2451541Srgrimes 2461541Srgrimes /* Fill in the next free callout structure. */ 24729680Sgibbs new = SLIST_FIRST(&callfree); 24829680Sgibbs if (new == NULL) 24929680Sgibbs /* XXX Attempt to malloc first */ 2501541Srgrimes panic("timeout table full"); 25129680Sgibbs SLIST_REMOVE_HEAD(&callfree, c_links.sle); 25244510Swollman 25344510Swollman callout_reset(new, to_ticks, ftn, arg); 2541541Srgrimes 25544510Swollman handle.callout = new; 25672200Sbmilekic mtx_unlock_spin(&callout_lock); 25729680Sgibbs return (handle); 2581541Srgrimes} 2591541Srgrimes 2601541Srgrimesvoid 26129680Sgibbsuntimeout(ftn, arg, handle) 26233824Sbde timeout_t *ftn; 2631541Srgrimes void *arg; 26429680Sgibbs struct callout_handle handle; 2651541Srgrimes{ 2661541Srgrimes 26729680Sgibbs /* 26829680Sgibbs * Check for a handle that was initialized 26929680Sgibbs * by callout_handle_init, but never used 27029680Sgibbs * for a real timeout. 27129680Sgibbs */ 27229680Sgibbs if (handle.callout == NULL) 27329680Sgibbs return; 27429680Sgibbs 27572200Sbmilekic mtx_lock_spin(&callout_lock); 27644510Swollman if (handle.callout->c_func == ftn && handle.callout->c_arg == arg) 27744510Swollman callout_stop(handle.callout); 27872200Sbmilekic mtx_unlock_spin(&callout_lock); 2791541Srgrimes} 2801541Srgrimes 28124101Sbdevoid 28229680Sgibbscallout_handle_init(struct callout_handle *handle) 28329680Sgibbs{ 28429680Sgibbs handle->callout = NULL; 28529680Sgibbs} 28629680Sgibbs 28744510Swollman/* 28844510Swollman * New interface; clients allocate their own callout structures. 28944510Swollman * 29044510Swollman * callout_reset() - establish or change a timeout 29144510Swollman * callout_stop() - disestablish a timeout 29244510Swollman * callout_init() - initialize a callout structure so that it can 29344510Swollman * safely be passed to callout_reset() and callout_stop() 29444510Swollman * 29550673Sjlemon * <sys/callout.h> defines three convenience macros: 29644510Swollman * 29750673Sjlemon * callout_active() - returns truth if callout has not been serviced 29850673Sjlemon * callout_pending() - returns truth if callout is still waiting for timeout 29950673Sjlemon * callout_deactivate() - marks the callout as having been serviced 30044510Swollman */ 30144510Swollmanvoid 30269147Sjlemoncallout_reset(c, to_ticks, ftn, arg) 30344510Swollman struct callout *c; 30444510Swollman int to_ticks; 30592723Salfred void (*ftn)(void *); 30644510Swollman void *arg; 30744510Swollman{ 30844510Swollman 30972200Sbmilekic mtx_lock_spin(&callout_lock); 31044510Swollman if (c->c_flags & CALLOUT_PENDING) 31144510Swollman callout_stop(c); 31244510Swollman 31344510Swollman /* 31481370Sjhb * We could unlock callout_lock here and lock it again before the 31581370Sjhb * TAILQ_INSERT_TAIL, but there's no point since doing this setup 31681370Sjhb * doesn't take much time. 31744510Swollman */ 31844510Swollman if (to_ticks <= 0) 31944510Swollman to_ticks = 1; 32044510Swollman 32144510Swollman c->c_arg = arg; 32269147Sjlemon c->c_flags |= (CALLOUT_ACTIVE | CALLOUT_PENDING); 32344510Swollman c->c_func = ftn; 32444510Swollman c->c_time = ticks + to_ticks; 32544510Swollman TAILQ_INSERT_TAIL(&callwheel[c->c_time & callwheelmask], 32644510Swollman c, c_links.tqe); 32772200Sbmilekic mtx_unlock_spin(&callout_lock); 32844510Swollman} 32944510Swollman 33081481Sjhbint 33144510Swollmancallout_stop(c) 33244510Swollman struct callout *c; 33344510Swollman{ 33444510Swollman 33572200Sbmilekic mtx_lock_spin(&callout_lock); 33644510Swollman /* 33744510Swollman * Don't attempt to delete a callout that's not on the queue. 33844510Swollman */ 33944510Swollman if (!(c->c_flags & CALLOUT_PENDING)) { 34050673Sjlemon c->c_flags &= ~CALLOUT_ACTIVE; 34172200Sbmilekic mtx_unlock_spin(&callout_lock); 34281481Sjhb return (0); 34344510Swollman } 34450673Sjlemon c->c_flags &= ~(CALLOUT_ACTIVE | CALLOUT_PENDING); 34544510Swollman 34644510Swollman if (nextsoftcheck == c) { 34744510Swollman nextsoftcheck = TAILQ_NEXT(c, c_links.tqe); 34844510Swollman } 34944510Swollman TAILQ_REMOVE(&callwheel[c->c_time & callwheelmask], c, c_links.tqe); 35044510Swollman c->c_func = NULL; 35144510Swollman 35244510Swollman if (c->c_flags & CALLOUT_LOCAL_ALLOC) { 35344510Swollman SLIST_INSERT_HEAD(&callfree, c, c_links.sle); 35444510Swollman } 35572200Sbmilekic mtx_unlock_spin(&callout_lock); 35681481Sjhb return (1); 35744510Swollman} 35844510Swollman 35944510Swollmanvoid 36069147Sjlemoncallout_init(c, mpsafe) 36144510Swollman struct callout *c; 36269147Sjlemon int mpsafe; 36344510Swollman{ 36444527Swollman bzero(c, sizeof *c); 36569147Sjlemon if (mpsafe) 36669147Sjlemon c->c_flags |= CALLOUT_MPSAFE; 36744510Swollman} 36844510Swollman 36931950Snate#ifdef APM_FIXUP_CALLTODO 37031950Snate/* 37131950Snate * Adjust the kernel calltodo timeout list. This routine is used after 37231950Snate * an APM resume to recalculate the calltodo timer list values with the 37331950Snate * number of hz's we have been sleeping. The next hardclock() will detect 37431950Snate * that there are fired timers and run softclock() to execute them. 37531950Snate * 37631950Snate * Please note, I have not done an exhaustive analysis of what code this 37731950Snate * might break. I am motivated to have my select()'s and alarm()'s that 37831950Snate * have expired during suspend firing upon resume so that the applications 37931950Snate * which set the timer can do the maintanence the timer was for as close 38031950Snate * as possible to the originally intended time. Testing this code for a 38131950Snate * week showed that resuming from a suspend resulted in 22 to 25 timers 38231950Snate * firing, which seemed independant on whether the suspend was 2 hours or 38331950Snate * 2 days. Your milage may vary. - Ken Key <key@cs.utk.edu> 38431950Snate */ 38531950Snatevoid 38631950Snateadjust_timeout_calltodo(time_change) 38731950Snate struct timeval *time_change; 38831950Snate{ 38931950Snate register struct callout *p; 39031950Snate unsigned long delta_ticks; 39131950Snate 39231950Snate /* 39331950Snate * How many ticks were we asleep? 39436127Sbde * (stolen from tvtohz()). 39531950Snate */ 39631950Snate 39731950Snate /* Don't do anything */ 39831950Snate if (time_change->tv_sec < 0) 39931950Snate return; 40031950Snate else if (time_change->tv_sec <= LONG_MAX / 1000000) 40131950Snate delta_ticks = (time_change->tv_sec * 1000000 + 40231950Snate time_change->tv_usec + (tick - 1)) / tick + 1; 40331950Snate else if (time_change->tv_sec <= LONG_MAX / hz) 40431950Snate delta_ticks = time_change->tv_sec * hz + 40531950Snate (time_change->tv_usec + (tick - 1)) / tick + 1; 40631950Snate else 40731950Snate delta_ticks = LONG_MAX; 40831950Snate 40931950Snate if (delta_ticks > INT_MAX) 41031950Snate delta_ticks = INT_MAX; 41131950Snate 41231950Snate /* 41331950Snate * Now rip through the timer calltodo list looking for timers 41431950Snate * to expire. 41531950Snate */ 41631950Snate 41731950Snate /* don't collide with softclock() */ 41872200Sbmilekic mtx_lock_spin(&callout_lock); 41931950Snate for (p = calltodo.c_next; p != NULL; p = p->c_next) { 42031950Snate p->c_time -= delta_ticks; 42131950Snate 42231950Snate /* Break if the timer had more time on it than delta_ticks */ 42331950Snate if (p->c_time > 0) 42431950Snate break; 42531950Snate 42631950Snate /* take back the ticks the timer didn't use (p->c_time <= 0) */ 42731950Snate delta_ticks = -p->c_time; 42831950Snate } 42972200Sbmilekic mtx_unlock_spin(&callout_lock); 43031950Snate 43131950Snate return; 43231950Snate} 43331950Snate#endif /* APM_FIXUP_CALLTODO */ 434