kern_timeout.c revision 68869
1139804Simp/*- 2185435Sbz * Copyright (c) 1982, 1986, 1991, 1993 3185435Sbz * The Regents of the University of California. All rights reserved. 4191673Sjamie * (c) UNIX System Laboratories, Inc. 5185435Sbz * All or some portions of this file are derived from material licensed 6190466Sjamie * to the University of California by American Telephone and Telegraph 7185404Sbz * Co. or Unix System Laboratories, Inc. and are reproduced herein with 8185404Sbz * the permission of UNIX System Laboratories, Inc. 9185404Sbz * 10185404Sbz * Redistribution and use in source and binary forms, with or without 11185404Sbz * modification, are permitted provided that the following conditions 12185404Sbz * are met: 13185404Sbz * 1. Redistributions of source code must retain the above copyright 14185404Sbz * notice, this list of conditions and the following disclaimer. 15185404Sbz * 2. Redistributions in binary form must reproduce the above copyright 16185404Sbz * notice, this list of conditions and the following disclaimer in the 17185404Sbz * documentation and/or other materials provided with the distribution. 18185404Sbz * 3. All advertising materials mentioning features or use of this software 19185404Sbz * must display the following acknowledgement: 20185404Sbz * This product includes software developed by the University of 21185404Sbz * California, Berkeley and its contributors. 22185404Sbz * 4. Neither the name of the University nor the names of its contributors 23185404Sbz * may be used to endorse or promote products derived from this software 24185404Sbz * without specific prior written permission. 25185404Sbz * 26185404Sbz * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 2746197Sphk * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 2846155Sphk * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 29116182Sobrien * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 30116182Sobrien * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 31116182Sobrien * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 32193066Sjamie * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 33185435Sbz * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 34185435Sbz * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 35185435Sbz * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 36131177Spjd * SUCH DAMAGE. 3746155Sphk * 3846155Sphk * From: @(#)kern_clock.c 8.5 (Berkeley) 1/21/94 3946155Sphk * $FreeBSD: head/sys/kern/kern_timeout.c 68869 2000-11-18 00:21:00Z jhb $ 4046155Sphk */ 4146155Sphk 4246155Sphk#include <sys/param.h> 4346155Sphk#include <sys/systm.h> 44192895Sjamie#include <sys/callout.h> 45164032Srwatson#include <sys/kernel.h> 4646155Sphk#include <sys/mutex.h> 47124882Srwatson 48177785Skib/* 4946155Sphk * TODO: 5087275Srwatson * allocate more timeout table slots when table overflows. 5187275Srwatson */ 52220137Strasz 53221362Strasz/* Exported to machdep.c and/or kern_clock.c. */ 54168401Spjdstruct callout *callout; 55193066Sjamiestruct callout_list callfree; 56113275Smikeint callwheelsize, callwheelbits, callwheelmask; 57147185Spjdstruct callout_tailq *callwheel; 58113275Smikeint softticks; /* Like ticks, but for softclock(). */ 5946155Sphk 60113275Smikestatic struct callout *nextsoftcheck; /* Next callout to be checked. */ 6157163Srwatson 62113275Smike/* 63196019Srwatson * The callout mechanism is based on the work of Adam M. Costello and 6446155Sphk * George Varghese, published in a technical report entitled "Redesigning 65196019Srwatson * the BSD Callout and Timer Facilities" and modified slightly for inclusion 66196019Srwatson * in FreeBSD by Justin T. Gibbs. The original work on the data structures 6746155Sphk * used in this implementation was published by G.Varghese and A. Lauck in 68196019Srwatson * the paper "Hashed and Hierarchical Timing Wheels: Data Structures for 69185435Sbz * the Efficient Implementation of a Timer Facility" in the Proceedings of 70185435Sbz * the 11th ACM Annual Symposium on Operating Systems Principles, 71185435Sbz * Austin, Texas Nov 1987. 72185435Sbz */ 73185435Sbz 74185435Sbz/* 7546155Sphk * Software (low priority) clock interrupt. 76163606Srwatson * Run periodic events from timeout queue. 77163606Srwatson */ 78195944Sjamievoid 79195944Sjamiesoftclock(void *dummy) 8046155Sphk{ 81227293Sed register struct callout *c; 8246155Sphk register struct callout_tailq *bucket; 83202468Sbz register int s; 84202468Sbz register int curticks; 85202468Sbz register int steps; /* #steps since we last allowed interrupts */ 86202468Sbz 87202468Sbz#ifndef MAX_SOFTCLOCK_STEPS 88202468Sbz#define MAX_SOFTCLOCK_STEPS 100 /* Maximum allowed value of steps. */ 89202468Sbz#endif /* MAX_SOFTCLOCK_STEPS */ 90202468Sbz 91202468Sbz steps = 0; 92202468Sbz s = splhigh(); 93202468Sbz mtx_enter(&sched_lock, MTX_SPIN); 94202468Sbz while (softticks != ticks) { 95202468Sbz softticks++; 96202468Sbz /* 97202468Sbz * softticks may be modified by hard clock, so cache 98192895Sjamie * it while we work on a given bucket. 99192895Sjamie */ 100192895Sjamie curticks = softticks; 101192895Sjamie bucket = &callwheel[curticks & callwheelmask]; 102192895Sjamie c = TAILQ_FIRST(bucket); 103192895Sjamie while (c) { 104192895Sjamie if (c->c_time != curticks) { 105192895Sjamie c = TAILQ_NEXT(c, c_links.tqe); 106231267Smm ++steps; 107194762Sjamie if (steps >= MAX_SOFTCLOCK_STEPS) { 108195944Sjamie nextsoftcheck = c; 109201145Santoine /* Give interrupts a chance. */ 110196176Sbz mtx_exit(&sched_lock, MTX_SPIN); 111202468Sbz splx(s); 112196176Sbz s = splhigh(); 113202468Sbz mtx_enter(&sched_lock, MTX_SPIN); 114196176Sbz c = nextsoftcheck; 115192895Sjamie steps = 0; 116192895Sjamie } 117192895Sjamie } else { 11857163Srwatson void (*c_func)(void *); 119221362Strasz void *c_arg; 120168401Spjd 121191673Sjamie nextsoftcheck = TAILQ_NEXT(c, c_links.tqe); 122191673Sjamie TAILQ_REMOVE(bucket, c, c_links.tqe); 123221362Strasz c_func = c->c_func; 124179881Sdelphij c_arg = c->c_arg; 125113275Smike c->c_func = NULL; 126191673Sjamie if (c->c_flags & CALLOUT_LOCAL_ALLOC) { 127190466Sjamie c->c_flags = CALLOUT_LOCAL_ALLOC; 128191673Sjamie SLIST_INSERT_HEAD(&callfree, c, 129192895Sjamie c_links.sle); 130192895Sjamie } else { 131221362Strasz c->c_flags = 132221362Strasz (c->c_flags & ~CALLOUT_PENDING); 133232598Strasz } 134221362Strasz mtx_exit(&sched_lock, MTX_SPIN); 135221362Strasz splx(s); 136185435Sbz c_func(c_arg); 137190466Sjamie s = splhigh(); 138192895Sjamie mtx_enter(&sched_lock, MTX_SPIN); 139185435Sbz steps = 0; 140185435Sbz c = nextsoftcheck; 141190466Sjamie } 142192895Sjamie } 143185435Sbz } 144113275Smike nextsoftcheck = NULL; 145191673Sjamie mtx_exit(&sched_lock, MTX_SPIN); 146191673Sjamie splx(s); 147191673Sjamie} 148191673Sjamie 149191673Sjamie/* 150191673Sjamie * timeout -- 151113275Smike * Execute a function after a specified length of time. 152192895Sjamie * 153216861Sbz * untimeout -- 154216861Sbz * Cancel previous timeout function call. 155216861Sbz * 156192895Sjamie * callout_handle_init -- 157192895Sjamie * Initialize a handle so that using it with untimeout is benign. 158192895Sjamie * 159202468Sbz * See AT&T BCI Driver Reference Manual for specification. This 160202468Sbz * implementation differs from that one in that although an 161202468Sbz * identification value is returned from timeout, the original 162202468Sbz * arguments to timeout as well as the identifier are used to 163202468Sbz * identify entries for untimeout. 164202468Sbz */ 165192895Sjamiestruct callout_handle 166216861Sbztimeout(ftn, arg, to_ticks) 167192895Sjamie timeout_t *ftn; 168192895Sjamie void *arg; 169192895Sjamie register int to_ticks; 170202468Sbz{ 171202468Sbz int s; 172202468Sbz struct callout *new; 173202468Sbz struct callout_handle handle; 174202468Sbz 175202468Sbz s = splhigh(); 176195870Sjamie mtx_enter(&sched_lock, MTX_SPIN); 177216861Sbz 178195870Sjamie /* Fill in the next free callout structure. */ 179195870Sjamie new = SLIST_FIRST(&callfree); 180195870Sjamie if (new == NULL) 181195870Sjamie /* XXX Attempt to malloc first */ 182195870Sjamie panic("timeout table full"); 183195870Sjamie SLIST_REMOVE_HEAD(&callfree, c_links.sle); 184195870Sjamie 185195870Sjamie callout_reset(new, to_ticks, ftn, arg); 186195870Sjamie 187195870Sjamie handle.callout = new; 188192895Sjamie mtx_exit(&sched_lock, MTX_SPIN); 189195870Sjamie splx(s); 190192895Sjamie return (handle); 191192895Sjamie} 192195870Sjamie 193192895Sjamievoid 194192895Sjamieuntimeout(ftn, arg, handle) 195216861Sbz timeout_t *ftn; 196192895Sjamie void *arg; 197192895Sjamie struct callout_handle handle; 198192895Sjamie{ 199192895Sjamie register int s; 200192895Sjamie 201192895Sjamie /* 202192895Sjamie * Check for a handle that was initialized 203192895Sjamie * by callout_handle_init, but never used 204192895Sjamie * for a real timeout. 205232059Smm */ 206232059Smm if (handle.callout == NULL) 207232186Smm return; 208232278Smm 209192895Sjamie s = splhigh(); 210216861Sbz mtx_enter(&sched_lock, MTX_SPIN); 211192895Sjamie if (handle.callout->c_func == ftn && handle.callout->c_arg == arg) 212192895Sjamie callout_stop(handle.callout); 213192895Sjamie mtx_exit(&sched_lock, MTX_SPIN); 214192895Sjamie splx(s); 215192895Sjamie} 216192895Sjamie 217192895Sjamievoid 218192895Sjamiecallout_handle_init(struct callout_handle *handle) 219192895Sjamie{ 220232059Smm handle->callout = NULL; 221232059Smm} 222232186Smm 223232278Smm/* 224192895Sjamie * New interface; clients allocate their own callout structures. 225216861Sbz * 226192895Sjamie * callout_reset() - establish or change a timeout 227196002Sjamie * callout_stop() - disestablish a timeout 228196002Sjamie * callout_init() - initialize a callout structure so that it can 229232059Smm * safely be passed to callout_reset() and callout_stop() 230192895Sjamie * 231196002Sjamie * <sys/callout.h> defines three convenience macros: 232231267Smm * 233192895Sjamie * callout_active() - returns truth if callout has not been serviced 234193865Sjamie * callout_pending() - returns truth if callout is still waiting for timeout 235192895Sjamie * callout_deactivate() - marks the callout as having been serviced 236192895Sjamie */ 237192895Sjamievoid 238185435Sbzcallout_reset(c, to_ticks, ftn, arg) 239185435Sbz struct callout *c; 240185435Sbz int to_ticks; 241185435Sbz void (*ftn) __P((void *)); 242185435Sbz void *arg; 243185435Sbz{ 244185435Sbz int s; 245185435Sbz 246185435Sbz s = splhigh(); 247185435Sbz mtx_enter(&sched_lock, MTX_SPIN); 248185435Sbz if (c->c_flags & CALLOUT_PENDING) 249185435Sbz callout_stop(c); 250185435Sbz 251185435Sbz /* 252185435Sbz * We could spl down here and back up at the TAILQ_INSERT_TAIL, 253185435Sbz * but there's no point since doing this setup doesn't take much 254185435Sbz * time. 255185435Sbz */ 256185435Sbz if (to_ticks <= 0) 257185435Sbz to_ticks = 1; 258185435Sbz 259185435Sbz c->c_arg = arg; 260185435Sbz c->c_flags |= (CALLOUT_ACTIVE | CALLOUT_PENDING); 261185435Sbz c->c_func = ftn; 262185435Sbz c->c_time = ticks + to_ticks; 263185435Sbz TAILQ_INSERT_TAIL(&callwheel[c->c_time & callwheelmask], 264185435Sbz c, c_links.tqe); 265185435Sbz mtx_exit(&sched_lock, MTX_SPIN); 266185435Sbz splx(s); 267185435Sbz} 268185435Sbz 269185435Sbzvoid 270185435Sbzcallout_stop(c) 271185435Sbz struct callout *c; 272185435Sbz{ 273185435Sbz int s; 274185435Sbz 275190466Sjamie s = splhigh(); 276185435Sbz mtx_enter(&sched_lock, MTX_SPIN); 277185435Sbz /* 278185435Sbz * Don't attempt to delete a callout that's not on the queue. 279185435Sbz */ 280185435Sbz if (!(c->c_flags & CALLOUT_PENDING)) { 281185435Sbz c->c_flags &= ~CALLOUT_ACTIVE; 282185435Sbz mtx_exit(&sched_lock, MTX_SPIN); 283185435Sbz splx(s); 284185435Sbz return; 285191673Sjamie } 286191673Sjamie c->c_flags &= ~(CALLOUT_ACTIVE | CALLOUT_PENDING); 287191673Sjamie 288191673Sjamie if (nextsoftcheck == c) { 289191673Sjamie nextsoftcheck = TAILQ_NEXT(c, c_links.tqe); 290191673Sjamie } 291225617Skmacy TAILQ_REMOVE(&callwheel[c->c_time & callwheelmask], c, c_links.tqe); 292185435Sbz c->c_func = NULL; 293191673Sjamie 294191673Sjamie if (c->c_flags & CALLOUT_LOCAL_ALLOC) { 295192895Sjamie SLIST_INSERT_HEAD(&callfree, c, c_links.sle); 296185435Sbz } 297191673Sjamie mtx_exit(&sched_lock, MTX_SPIN); 298191673Sjamie splx(s); 299191673Sjamie} 300185435Sbz 301191673Sjamievoid 302191673Sjamiecallout_init(c) 303191673Sjamie struct callout *c; 304191673Sjamie{ 305185435Sbz bzero(c, sizeof *c); 306192895Sjamie} 307192895Sjamie 308191673Sjamie#ifdef APM_FIXUP_CALLTODO 309191673Sjamie/* 310191673Sjamie * Adjust the kernel calltodo timeout list. This routine is used after 311192895Sjamie * an APM resume to recalculate the calltodo timer list values with the 312192895Sjamie * number of hz's we have been sleeping. The next hardclock() will detect 313192895Sjamie * that there are fired timers and run softclock() to execute them. 314192895Sjamie * 315191673Sjamie * Please note, I have not done an exhaustive analysis of what code this 316191673Sjamie * might break. I am motivated to have my select()'s and alarm()'s that 317191673Sjamie * have expired during suspend firing upon resume so that the applications 318191673Sjamie * which set the timer can do the maintanence the timer was for as close 319185435Sbz * as possible to the originally intended time. Testing this code for a 320191673Sjamie * week showed that resuming from a suspend resulted in 22 to 25 timers 321191673Sjamie * firing, which seemed independant on whether the suspend was 2 hours or 322185435Sbz * 2 days. Your milage may vary. - Ken Key <key@cs.utk.edu> 323191673Sjamie */ 324185435Sbzvoid 325191673Sjamieadjust_timeout_calltodo(time_change) 326191673Sjamie struct timeval *time_change; 327191673Sjamie{ 328191673Sjamie register struct callout *p; 329191673Sjamie unsigned long delta_ticks; 330192895Sjamie int s; 331192895Sjamie 332192895Sjamie /* 333192895Sjamie * How many ticks were we asleep? 334192895Sjamie * (stolen from tvtohz()). 335192895Sjamie */ 336192895Sjamie 337192895Sjamie /* Don't do anything */ 338192895Sjamie if (time_change->tv_sec < 0) 339192895Sjamie return; 340192895Sjamie else if (time_change->tv_sec <= LONG_MAX / 1000000) 341192895Sjamie delta_ticks = (time_change->tv_sec * 1000000 + 342193865Sjamie time_change->tv_usec + (tick - 1)) / tick + 1; 343193865Sjamie else if (time_change->tv_sec <= LONG_MAX / hz) 344193865Sjamie delta_ticks = time_change->tv_sec * hz + 345193865Sjamie (time_change->tv_usec + (tick - 1)) / tick + 1; 346193865Sjamie else 347193865Sjamie delta_ticks = LONG_MAX; 348193865Sjamie 349193865Sjamie if (delta_ticks > INT_MAX) 350193865Sjamie delta_ticks = INT_MAX; 351192895Sjamie 352192895Sjamie /* 353185435Sbz * Now rip through the timer calltodo list looking for timers 354193865Sjamie * to expire. 355192895Sjamie */ 356192895Sjamie 357192895Sjamie /* don't collide with softclock() */ 358192895Sjamie s = splhigh(); 359192895Sjamie mtx_enter(&sched_lock, MTX_SPIN); 360192895Sjamie for (p = calltodo.c_next; p != NULL; p = p->c_next) { 361192895Sjamie p->c_time -= delta_ticks; 362192895Sjamie 363192895Sjamie /* Break if the timer had more time on it than delta_ticks */ 364192895Sjamie if (p->c_time > 0) 365192895Sjamie break; 366192895Sjamie 367192895Sjamie /* take back the ticks the timer didn't use (p->c_time <= 0) */ 368192895Sjamie delta_ticks = -p->c_time; 369192895Sjamie } 370192895Sjamie mtx_exit(&sched_lock, MTX_SPIN); 371192895Sjamie splx(s); 372192895Sjamie 373192895Sjamie return; 374192895Sjamie} 375192895Sjamie#endif /* APM_FIXUP_CALLTODO */ 376192895Sjamie