kern_timeout.c revision 33824
1186681Sed/*- 2186681Sed * Copyright (c) 1982, 1986, 1991, 1993 3186681Sed * The Regents of the University of California. All rights reserved. 4186681Sed * (c) UNIX System Laboratories, Inc. 5186681Sed * All or some portions of this file are derived from material licensed 6186681Sed * to the University of California by American Telephone and Telegraph 7186681Sed * Co. or Unix System Laboratories, Inc. and are reproduced herein with 8186681Sed * the permission of UNIX System Laboratories, Inc. 9186681Sed * 10186681Sed * Redistribution and use in source and binary forms, with or without 11186681Sed * modification, are permitted provided that the following conditions 12186681Sed * are met: 13186681Sed * 1. Redistributions of source code must retain the above copyright 14186681Sed * notice, this list of conditions and the following disclaimer. 15186681Sed * 2. Redistributions in binary form must reproduce the above copyright 16186681Sed * notice, this list of conditions and the following disclaimer in the 17186681Sed * documentation and/or other materials provided with the distribution. 18186681Sed * 3. All advertising materials mentioning features or use of this software 19186681Sed * must display the following acknowledgement: 20186681Sed * This product includes software developed by the University of 21186681Sed * California, Berkeley and its contributors. 22186681Sed * 4. Neither the name of the University nor the names of its contributors 23186681Sed * may be used to endorse or promote products derived from this software 24186681Sed * without specific prior written permission. 25186681Sed * 26186681Sed * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 27186681Sed * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 28186681Sed * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 29186681Sed * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 30186681Sed * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 31186681Sed * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 32186681Sed * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 33186681Sed * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 34186681Sed * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 35186681Sed * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 36187367Sed * SUCH DAMAGE. 37187367Sed * 38187367Sed * @(#)kern_clock.c 8.5 (Berkeley) 1/21/94 39187367Sed * $Id: kern_timeout.c,v 1.53 1998/02/15 14:15:21 phk Exp $ 40187367Sed */ 41186681Sed 42186681Sed#include <sys/param.h> 43187367Sed#include <sys/systm.h> 44187367Sed#include <sys/callout.h> 45187367Sed#include <sys/kernel.h> 46186681Sed 47186681Sed/* 48186681Sed * TODO: 49186681Sed * allocate more timeout table slots when table overflows. 50186681Sed */ 51186681Sed 52186681Sed/* Exported to machdep.c and/or kern_clock.c. */ 53186681Sedstruct callout *callout; 54186681Sedstruct callout_list callfree; 55186681Sedint callwheelsize, callwheelbits, callwheelmask; 56186681Sedstruct callout_tailq *callwheel; 57186681Sedint softticks; /* Like ticks, but for softclock(). */ 58186681Sed 59186681Sedstatic struct callout *nextsoftcheck; /* Next callout to be checked. */ 60186681Sed 61186681Sed/* 62186681Sed * The callout mechanism is based on the work of Adam M. Costello and 63186681Sed * George Varghese, published in a technical report entitled "Redesigning 64186681Sed * the BSD Callout and Timer Facilities" and modified slightly for inclusion 65186681Sed * in FreeBSD by Justin T. Gibbs. The original work on the data structures 66186681Sed * used in this implementation was published by G.Varghese and A. Lauck in 67186681Sed * the paper "Hashed and Hierarchical Timing Wheels: Data Structures for 68186681Sed * the Efficient Implementation of a Timer Facility" in the Proceedings of 69186681Sed * the 11th ACM Annual Symposium on Operating Systems Principles, 70186681Sed * Austin, Texas Nov 1987. 71186681Sed */ 72186681Sed 73186681Sed/* 74186681Sed * Software (low priority) clock interrupt. 75186681Sed * Run periodic events from timeout queue. 76186681Sed */ 77186681Sedvoid 78186681Sedsoftclock() 79186681Sed{ 80186681Sed register struct callout *c; 81186681Sed register struct callout_tailq *bucket; 82186681Sed register int s; 83186681Sed register int curticks; 84186681Sed register int steps; /* #steps since we last allowed interrupts */ 85186681Sed 86186681Sed#ifndef MAX_SOFTCLOCK_STEPS 87186681Sed#define MAX_SOFTCLOCK_STEPS 100 /* Maximum allowed value of steps. */ 88186681Sed#endif /* MAX_SOFTCLOCK_STEPS */ 89186681Sed 90186681Sed steps = 0; 91186681Sed s = splhigh(); 92186681Sed while (softticks != ticks) { 93186681Sed softticks++; 94186681Sed /* 95186681Sed * softticks may be modified by hard clock, so cache 96186681Sed * it while we work on a given bucket. 97186681Sed */ 98186681Sed curticks = softticks; 99186681Sed bucket = &callwheel[curticks & callwheelmask]; 100186681Sed c = TAILQ_FIRST(bucket); 101193184Sed while (c) { 102186681Sed if (c->c_time != curticks) { 103186681Sed c = TAILQ_NEXT(c, c_links.tqe); 104186681Sed ++steps; 105186681Sed if (steps >= MAX_SOFTCLOCK_STEPS) { 106186681Sed nextsoftcheck = c; 107186681Sed /* Give interrupts a chance. */ 108193184Sed splx(s); 109193184Sed s = splhigh(); 110193184Sed c = nextsoftcheck; 111186681Sed steps = 0; 112186681Sed } 113186681Sed } else { 114186681Sed void (*c_func)(void *); 115186681Sed void *c_arg; 116186681Sed 117186681Sed nextsoftcheck = TAILQ_NEXT(c, c_links.tqe); 118186681Sed TAILQ_REMOVE(bucket, c, c_links.tqe); 119186681Sed c_func = c->c_func; 120186681Sed c_arg = c->c_arg; 121186681Sed c->c_func = NULL; 122186681Sed SLIST_INSERT_HEAD(&callfree, c, c_links.sle); 123187469Sed splx(s); 124187469Sed c_func(c_arg); 125187469Sed s = splhigh(); 126187469Sed steps = 0; 127186681Sed c = nextsoftcheck; 128186681Sed } 129186681Sed } 130186681Sed } 131186681Sed nextsoftcheck = NULL; 132186681Sed splx(s); 133186681Sed} 134186681Sed 135186681Sed/* 136186681Sed * timeout -- 137186681Sed * Execute a function after a specified length of time. 138186681Sed * 139186681Sed * untimeout -- 140186681Sed * Cancel previous timeout function call. 141186681Sed * 142186681Sed * callout_handle_init -- 143186681Sed * Initialize a handle so that using it with untimeout is benign. 144186681Sed * 145186681Sed * See AT&T BCI Driver Reference Manual for specification. This 146186681Sed * implementation differs from that one in that although an 147186681Sed * identification value is returned from timeout, the original 148186681Sed * arguments to timeout as well as the identifier are used to 149186681Sed * identify entries for untimeout. 150186681Sed */ 151186681Sedstruct callout_handle 152186681Sedtimeout(ftn, arg, to_ticks) 153186681Sed timeout_t *ftn; 154186681Sed void *arg; 155186681Sed register int to_ticks; 156187469Sed{ 157186681Sed int s; 158186681Sed struct callout *new; 159187469Sed struct callout_handle handle; 160187469Sed 161186681Sed if (to_ticks <= 0) 162187469Sed to_ticks = 1; 163187469Sed 164187469Sed /* Lock out the clock. */ 165187469Sed s = splhigh(); 166187469Sed 167187469Sed /* Fill in the next free callout structure. */ 168186681Sed new = SLIST_FIRST(&callfree); 169186681Sed if (new == NULL) 170186681Sed /* XXX Attempt to malloc first */ 171186681Sed panic("timeout table full"); 172186681Sed 173186681Sed SLIST_REMOVE_HEAD(&callfree, c_links.sle); 174186681Sed new->c_arg = arg; 175186681Sed new->c_func = ftn; 176188391Sed new->c_time = ticks + to_ticks; 177188391Sed TAILQ_INSERT_TAIL(&callwheel[new->c_time & callwheelmask], 178188391Sed new, c_links.tqe); 179186681Sed 180189617Sed splx(s); 181186681Sed handle.callout = new; 182186681Sed return (handle); 183186681Sed} 184186681Sed 185void 186untimeout(ftn, arg, handle) 187 timeout_t *ftn; 188 void *arg; 189 struct callout_handle handle; 190{ 191 register int s; 192 193 /* 194 * Check for a handle that was initialized 195 * by callout_handle_init, but never used 196 * for a real timeout. 197 */ 198 if (handle.callout == NULL) 199 return; 200 201 s = splhigh(); 202 if ((handle.callout->c_func == ftn) 203 && (handle.callout->c_arg == arg)) { 204 if (nextsoftcheck == handle.callout) { 205 nextsoftcheck = TAILQ_NEXT(handle.callout, c_links.tqe); 206 } 207 TAILQ_REMOVE(&callwheel[handle.callout->c_time & callwheelmask], 208 handle.callout, c_links.tqe); 209 handle.callout->c_func = NULL; 210 SLIST_INSERT_HEAD(&callfree, handle.callout, c_links.sle); 211 } 212 splx(s); 213} 214 215void 216callout_handle_init(struct callout_handle *handle) 217{ 218 handle->callout = NULL; 219} 220 221#ifdef APM_FIXUP_CALLTODO 222/* 223 * Adjust the kernel calltodo timeout list. This routine is used after 224 * an APM resume to recalculate the calltodo timer list values with the 225 * number of hz's we have been sleeping. The next hardclock() will detect 226 * that there are fired timers and run softclock() to execute them. 227 * 228 * Please note, I have not done an exhaustive analysis of what code this 229 * might break. I am motivated to have my select()'s and alarm()'s that 230 * have expired during suspend firing upon resume so that the applications 231 * which set the timer can do the maintanence the timer was for as close 232 * as possible to the originally intended time. Testing this code for a 233 * week showed that resuming from a suspend resulted in 22 to 25 timers 234 * firing, which seemed independant on whether the suspend was 2 hours or 235 * 2 days. Your milage may vary. - Ken Key <key@cs.utk.edu> 236 */ 237void 238adjust_timeout_calltodo(time_change) 239 struct timeval *time_change; 240{ 241 register struct callout *p; 242 unsigned long delta_ticks; 243 int s; 244 245 /* 246 * How many ticks were we asleep? 247 * (stolen from hzto()). 248 */ 249 250 /* Don't do anything */ 251 if (time_change->tv_sec < 0) 252 return; 253 else if (time_change->tv_sec <= LONG_MAX / 1000000) 254 delta_ticks = (time_change->tv_sec * 1000000 + 255 time_change->tv_usec + (tick - 1)) / tick + 1; 256 else if (time_change->tv_sec <= LONG_MAX / hz) 257 delta_ticks = time_change->tv_sec * hz + 258 (time_change->tv_usec + (tick - 1)) / tick + 1; 259 else 260 delta_ticks = LONG_MAX; 261 262 if (delta_ticks > INT_MAX) 263 delta_ticks = INT_MAX; 264 265 /* 266 * Now rip through the timer calltodo list looking for timers 267 * to expire. 268 */ 269 270 /* don't collide with softclock() */ 271 s = splhigh(); 272 for (p = calltodo.c_next; p != NULL; p = p->c_next) { 273 p->c_time -= delta_ticks; 274 275 /* Break if the timer had more time on it than delta_ticks */ 276 if (p->c_time > 0) 277 break; 278 279 /* take back the ticks the timer didn't use (p->c_time <= 0) */ 280 delta_ticks = -p->c_time; 281 } 282 splx(s); 283 284 return; 285} 286#endif /* APM_FIXUP_CALLTODO */ 287