kern_timeout.c revision 33392
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 * 381541Srgrimes * @(#)kern_clock.c 8.5 (Berkeley) 1/21/94 3933392Sphk * $Id: kern_timeout.c,v 1.52 1998/01/14 19:42:47 phk Exp $ 401541Srgrimes */ 411541Srgrimes 421541Srgrimes#include <sys/param.h> 431541Srgrimes#include <sys/systm.h> 4433392Sphk#include <sys/callout.h> 451541Srgrimes#include <sys/kernel.h> 461541Srgrimes 4733392Sphk/* 4833392Sphk * TODO: 4933392Sphk * allocate more timeout table slots when table overflows. 5033392Sphk */ 5133392Sphk 5233392Sphk/* Exported to machdep.c and/or kern_clock.c. */ 5329680Sgibbsstruct callout *callout; 5429680Sgibbsstruct callout_list callfree; 5529680Sgibbsint callwheelsize, callwheelbits, callwheelmask; 5629680Sgibbsstruct callout_tailq *callwheel; 5733392Sphkint softticks; /* Like ticks, but for softclock(). */ 582112Swollman 5929680Sgibbsstatic struct callout *nextsoftcheck; /* Next callout to be checked. */ 601541Srgrimes 611541Srgrimes/* 6229680Sgibbs * The callout mechanism is based on the work of Adam M. Costello and 6329680Sgibbs * George Varghese, published in a technical report entitled "Redesigning 6429680Sgibbs * the BSD Callout and Timer Facilities" and modified slightly for inclusion 6529680Sgibbs * in FreeBSD by Justin T. Gibbs. The original work on the data structures 6629680Sgibbs * used in this implementation was published by G.Varghese and A. Lauck in 6729680Sgibbs * the paper "Hashed and Hierarchical Timing Wheels: Data Structures for 6829680Sgibbs * the Efficient Implementation of a Timer Facility" in the Proceedings of 6929680Sgibbs * the 11th ACM Annual Symposium on Operating Systems Principles, 7029680Sgibbs * Austin, Texas Nov 1987. 7129680Sgibbs */ 7232388Sphk 7329680Sgibbs/* 741541Srgrimes * Software (low priority) clock interrupt. 751541Srgrimes * Run periodic events from timeout queue. 761541Srgrimes */ 771541Srgrimesvoid 7832391Sphksoftclock() 791541Srgrimes{ 801541Srgrimes register struct callout *c; 8129805Sgibbs register struct callout_tailq *bucket; 821541Srgrimes register int s; 8329805Sgibbs register int curticks; 8433392Sphk register int steps; /* #steps since we last allowed interrupts */ 851541Srgrimes 8633392Sphk#ifndef MAX_SOFTCLOCK_STEPS 8733392Sphk#define MAX_SOFTCLOCK_STEPS 100 /* Maximum allowed value of steps. */ 8833392Sphk#endif /* MAX_SOFTCLOCK_STEPS */ 8929680Sgibbs 9029680Sgibbs steps = 0; 911541Srgrimes s = splhigh(); 9229680Sgibbs while (softticks != ticks) { 9329805Sgibbs softticks++; 9429805Sgibbs /* 9529805Sgibbs * softticks may be modified by hard clock, so cache 9629805Sgibbs * it while we work on a given bucket. 9729805Sgibbs */ 9829805Sgibbs curticks = softticks; 9929805Sgibbs bucket = &callwheel[curticks & callwheelmask]; 10029805Sgibbs c = TAILQ_FIRST(bucket); 10129680Sgibbs while (c) { 10229805Sgibbs if (c->c_time != curticks) { 10329680Sgibbs c = TAILQ_NEXT(c, c_links.tqe); 10429680Sgibbs ++steps; 10529680Sgibbs if (steps >= MAX_SOFTCLOCK_STEPS) { 10629680Sgibbs nextsoftcheck = c; 10729805Sgibbs /* Give interrupts a chance. */ 10829680Sgibbs splx(s); 10929680Sgibbs s = splhigh(); 11029680Sgibbs c = nextsoftcheck; 11129680Sgibbs steps = 0; 11229680Sgibbs } 11329680Sgibbs } else { 11429680Sgibbs void (*c_func)(void *); 11529680Sgibbs void *c_arg; 11629680Sgibbs 11729680Sgibbs nextsoftcheck = TAILQ_NEXT(c, c_links.tqe); 11829805Sgibbs TAILQ_REMOVE(bucket, c, c_links.tqe); 11929680Sgibbs c_func = c->c_func; 12029680Sgibbs c_arg = c->c_arg; 12129680Sgibbs c->c_func = NULL; 12229680Sgibbs SLIST_INSERT_HEAD(&callfree, c, c_links.sle); 12329680Sgibbs splx(s); 12429680Sgibbs c_func(c_arg); 12529680Sgibbs s = splhigh(); 12629680Sgibbs steps = 0; 12729680Sgibbs c = nextsoftcheck; 12829680Sgibbs } 12929680Sgibbs } 1301541Srgrimes } 13129680Sgibbs nextsoftcheck = NULL; 1321541Srgrimes splx(s); 1331541Srgrimes} 1341541Srgrimes 1351541Srgrimes/* 1361541Srgrimes * timeout -- 1371541Srgrimes * Execute a function after a specified length of time. 1381541Srgrimes * 1391541Srgrimes * untimeout -- 1401541Srgrimes * Cancel previous timeout function call. 1411541Srgrimes * 14229680Sgibbs * callout_handle_init -- 14329680Sgibbs * Initialize a handle so that using it with untimeout is benign. 14429680Sgibbs * 1451541Srgrimes * See AT&T BCI Driver Reference Manual for specification. This 14629680Sgibbs * implementation differs from that one in that although an 14729680Sgibbs * identification value is returned from timeout, the original 14829680Sgibbs * arguments to timeout as well as the identifier are used to 14929680Sgibbs * identify entries for untimeout. 1501541Srgrimes */ 15129680Sgibbsstruct callout_handle 15229680Sgibbstimeout(ftn, arg, to_ticks) 1532112Swollman timeout_t ftn; 1541541Srgrimes void *arg; 15529680Sgibbs register int to_ticks; 1561541Srgrimes{ 15729680Sgibbs int s; 15829680Sgibbs struct callout *new; 15929680Sgibbs struct callout_handle handle; 1601541Srgrimes 16129680Sgibbs if (to_ticks <= 0) 16229680Sgibbs to_ticks = 1; 1631541Srgrimes 1641541Srgrimes /* Lock out the clock. */ 1651541Srgrimes s = splhigh(); 1661541Srgrimes 1671541Srgrimes /* Fill in the next free callout structure. */ 16829680Sgibbs new = SLIST_FIRST(&callfree); 16929680Sgibbs if (new == NULL) 17029680Sgibbs /* XXX Attempt to malloc first */ 1711541Srgrimes panic("timeout table full"); 17229680Sgibbs 17329680Sgibbs SLIST_REMOVE_HEAD(&callfree, c_links.sle); 1741541Srgrimes new->c_arg = arg; 1751541Srgrimes new->c_func = ftn; 17629805Sgibbs new->c_time = ticks + to_ticks; 17729805Sgibbs TAILQ_INSERT_TAIL(&callwheel[new->c_time & callwheelmask], 17829805Sgibbs new, c_links.tqe); 1791541Srgrimes 1801541Srgrimes splx(s); 18129680Sgibbs handle.callout = new; 18229680Sgibbs return (handle); 1831541Srgrimes} 1841541Srgrimes 1851541Srgrimesvoid 18629680Sgibbsuntimeout(ftn, arg, handle) 1872112Swollman timeout_t ftn; 1881541Srgrimes void *arg; 18929680Sgibbs struct callout_handle handle; 1901541Srgrimes{ 1911541Srgrimes register int s; 1921541Srgrimes 19329680Sgibbs /* 19429680Sgibbs * Check for a handle that was initialized 19529680Sgibbs * by callout_handle_init, but never used 19629680Sgibbs * for a real timeout. 19729680Sgibbs */ 19829680Sgibbs if (handle.callout == NULL) 19929680Sgibbs return; 20029680Sgibbs 2011541Srgrimes s = splhigh(); 20229680Sgibbs if ((handle.callout->c_func == ftn) 20329680Sgibbs && (handle.callout->c_arg == arg)) { 20429680Sgibbs if (nextsoftcheck == handle.callout) { 20529680Sgibbs nextsoftcheck = TAILQ_NEXT(handle.callout, c_links.tqe); 2061541Srgrimes } 20729805Sgibbs TAILQ_REMOVE(&callwheel[handle.callout->c_time & callwheelmask], 20829680Sgibbs handle.callout, c_links.tqe); 20929680Sgibbs handle.callout->c_func = NULL; 21029680Sgibbs SLIST_INSERT_HEAD(&callfree, handle.callout, c_links.sle); 21129680Sgibbs } 2121541Srgrimes splx(s); 2131541Srgrimes} 2141541Srgrimes 21524101Sbdevoid 21629680Sgibbscallout_handle_init(struct callout_handle *handle) 21729680Sgibbs{ 21829680Sgibbs handle->callout = NULL; 21929680Sgibbs} 22029680Sgibbs 22131950Snate#ifdef APM_FIXUP_CALLTODO 22231950Snate/* 22331950Snate * Adjust the kernel calltodo timeout list. This routine is used after 22431950Snate * an APM resume to recalculate the calltodo timer list values with the 22531950Snate * number of hz's we have been sleeping. The next hardclock() will detect 22631950Snate * that there are fired timers and run softclock() to execute them. 22731950Snate * 22831950Snate * Please note, I have not done an exhaustive analysis of what code this 22931950Snate * might break. I am motivated to have my select()'s and alarm()'s that 23031950Snate * have expired during suspend firing upon resume so that the applications 23131950Snate * which set the timer can do the maintanence the timer was for as close 23231950Snate * as possible to the originally intended time. Testing this code for a 23331950Snate * week showed that resuming from a suspend resulted in 22 to 25 timers 23431950Snate * firing, which seemed independant on whether the suspend was 2 hours or 23531950Snate * 2 days. Your milage may vary. - Ken Key <key@cs.utk.edu> 23631950Snate */ 23731950Snatevoid 23831950Snateadjust_timeout_calltodo(time_change) 23931950Snate struct timeval *time_change; 24031950Snate{ 24131950Snate register struct callout *p; 24231950Snate unsigned long delta_ticks; 24331950Snate int s; 24431950Snate 24531950Snate /* 24631950Snate * How many ticks were we asleep? 24731950Snate * (stolen from hzto()). 24831950Snate */ 24931950Snate 25031950Snate /* Don't do anything */ 25131950Snate if (time_change->tv_sec < 0) 25231950Snate return; 25331950Snate else if (time_change->tv_sec <= LONG_MAX / 1000000) 25431950Snate delta_ticks = (time_change->tv_sec * 1000000 + 25531950Snate time_change->tv_usec + (tick - 1)) / tick + 1; 25631950Snate else if (time_change->tv_sec <= LONG_MAX / hz) 25731950Snate delta_ticks = time_change->tv_sec * hz + 25831950Snate (time_change->tv_usec + (tick - 1)) / tick + 1; 25931950Snate else 26031950Snate delta_ticks = LONG_MAX; 26131950Snate 26231950Snate if (delta_ticks > INT_MAX) 26331950Snate delta_ticks = INT_MAX; 26431950Snate 26531950Snate /* 26631950Snate * Now rip through the timer calltodo list looking for timers 26731950Snate * to expire. 26831950Snate */ 26931950Snate 27031950Snate /* don't collide with softclock() */ 27131950Snate s = splhigh(); 27231950Snate for (p = calltodo.c_next; p != NULL; p = p->c_next) { 27331950Snate p->c_time -= delta_ticks; 27431950Snate 27531950Snate /* Break if the timer had more time on it than delta_ticks */ 27631950Snate if (p->c_time > 0) 27731950Snate break; 27831950Snate 27931950Snate /* take back the ticks the timer didn't use (p->c_time <= 0) */ 28031950Snate delta_ticks = -p->c_time; 28131950Snate } 28231950Snate splx(s); 28331950Snate 28431950Snate return; 28531950Snate} 28631950Snate#endif /* APM_FIXUP_CALLTODO */ 287