kern_timeout.c revision 102936
1/*- 2 * Copyright (c) 1982, 1986, 1991, 1993 3 * The Regents of the University of California. All rights reserved. 4 * (c) UNIX System Laboratories, Inc. 5 * All or some portions of this file are derived from material licensed 6 * to the University of California by American Telephone and Telegraph 7 * Co. or Unix System Laboratories, Inc. and are reproduced herein with 8 * the permission of UNIX System Laboratories, Inc. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 3. All advertising materials mentioning features or use of this software 19 * must display the following acknowledgement: 20 * This product includes software developed by the University of 21 * California, Berkeley and its contributors. 22 * 4. Neither the name of the University nor the names of its contributors 23 * may be used to endorse or promote products derived from this software 24 * without specific prior written permission. 25 * 26 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 27 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 28 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 29 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 30 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 31 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 32 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 33 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 34 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 35 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 36 * SUCH DAMAGE. 37 * 38 * From: @(#)kern_clock.c 8.5 (Berkeley) 1/21/94 39 * $FreeBSD: head/sys/kern/kern_timeout.c 102936 2002-09-04 20:05:00Z phk $ 40 */ 41 42#include <sys/param.h> 43#include <sys/systm.h> 44#include <sys/callout.h> 45#include <sys/kernel.h> 46#include <sys/lock.h> 47#include <sys/mutex.h> 48 49/* 50 * TODO: 51 * allocate more timeout table slots when table overflows. 52 */ 53 54/* Exported to machdep.c and/or kern_clock.c. */ 55struct callout *callout; 56struct callout_list callfree; 57int callwheelsize, callwheelbits, callwheelmask; 58struct callout_tailq *callwheel; 59int softticks; /* Like ticks, but for softclock(). */ 60struct mtx callout_lock; 61 62static struct callout *nextsoftcheck; /* Next callout to be checked. */ 63 64/* 65 * kern_timeout_callwheel_alloc() - kernel low level callwheel initialization 66 * 67 * This code is called very early in the kernel initialization sequence, 68 * and may be called more then once. 69 */ 70caddr_t 71kern_timeout_callwheel_alloc(caddr_t v) 72{ 73 /* 74 * Calculate callout wheel size 75 */ 76 for (callwheelsize = 1, callwheelbits = 0; 77 callwheelsize < ncallout; 78 callwheelsize <<= 1, ++callwheelbits) 79 ; 80 callwheelmask = callwheelsize - 1; 81 82 callout = (struct callout *)v; 83 v = (caddr_t)(callout + ncallout); 84 callwheel = (struct callout_tailq *)v; 85 v = (caddr_t)(callwheel + callwheelsize); 86 return(v); 87} 88 89/* 90 * kern_timeout_callwheel_init() - initialize previously reserved callwheel 91 * space. 92 * 93 * This code is called just once, after the space reserved for the 94 * callout wheel has been finalized. 95 */ 96void 97kern_timeout_callwheel_init(void) 98{ 99 int i; 100 101 SLIST_INIT(&callfree); 102 for (i = 0; i < ncallout; i++) { 103 callout_init(&callout[i], 0); 104 callout[i].c_flags = CALLOUT_LOCAL_ALLOC; 105 SLIST_INSERT_HEAD(&callfree, &callout[i], c_links.sle); 106 } 107 for (i = 0; i < callwheelsize; i++) { 108 TAILQ_INIT(&callwheel[i]); 109 } 110 mtx_init(&callout_lock, "callout", NULL, MTX_SPIN | MTX_RECURSE); 111} 112 113/* 114 * The callout mechanism is based on the work of Adam M. Costello and 115 * George Varghese, published in a technical report entitled "Redesigning 116 * the BSD Callout and Timer Facilities" and modified slightly for inclusion 117 * in FreeBSD by Justin T. Gibbs. The original work on the data structures 118 * used in this implementation was published by G.Varghese and A. Lauck in 119 * the paper "Hashed and Hierarchical Timing Wheels: Data Structures for 120 * the Efficient Implementation of a Timer Facility" in the Proceedings of 121 * the 11th ACM Annual Symposium on Operating Systems Principles, 122 * Austin, Texas Nov 1987. 123 */ 124 125/* 126 * Software (low priority) clock interrupt. 127 * Run periodic events from timeout queue. 128 */ 129void 130softclock(void *dummy) 131{ 132 struct callout *c; 133 struct callout_tailq *bucket; 134 int curticks; 135 int steps; /* #steps since we last allowed interrupts */ 136#ifdef DIAGNOSTIC 137 struct bintime bt1, bt2; 138 struct timespec ts2; 139 static uint64_t maxdt = 18446744073709551LL; /* 1 msec */ 140#endif 141 142#ifndef MAX_SOFTCLOCK_STEPS 143#define MAX_SOFTCLOCK_STEPS 100 /* Maximum allowed value of steps. */ 144#endif /* MAX_SOFTCLOCK_STEPS */ 145 146 steps = 0; 147 mtx_lock_spin(&callout_lock); 148 while (softticks != ticks) { 149 softticks++; 150 /* 151 * softticks may be modified by hard clock, so cache 152 * it while we work on a given bucket. 153 */ 154 curticks = softticks; 155 bucket = &callwheel[curticks & callwheelmask]; 156 c = TAILQ_FIRST(bucket); 157 while (c) { 158 if (c->c_time != curticks) { 159 c = TAILQ_NEXT(c, c_links.tqe); 160 ++steps; 161 if (steps >= MAX_SOFTCLOCK_STEPS) { 162 nextsoftcheck = c; 163 /* Give interrupts a chance. */ 164 mtx_unlock_spin(&callout_lock); 165 ; /* nothing */ 166 mtx_lock_spin(&callout_lock); 167 c = nextsoftcheck; 168 steps = 0; 169 } 170 } else { 171 void (*c_func)(void *); 172 void *c_arg; 173 int c_flags; 174 175 nextsoftcheck = TAILQ_NEXT(c, c_links.tqe); 176 TAILQ_REMOVE(bucket, c, c_links.tqe); 177 c_func = c->c_func; 178 c_arg = c->c_arg; 179 c_flags = c->c_flags; 180 c->c_func = NULL; 181 if (c->c_flags & CALLOUT_LOCAL_ALLOC) { 182 c->c_flags = CALLOUT_LOCAL_ALLOC; 183 SLIST_INSERT_HEAD(&callfree, c, 184 c_links.sle); 185 } else { 186 c->c_flags = 187 (c->c_flags & ~CALLOUT_PENDING); 188 } 189 mtx_unlock_spin(&callout_lock); 190 if (!(c_flags & CALLOUT_MPSAFE)) 191 mtx_lock(&Giant); 192#ifdef DIAGNOSTIC 193 binuptime(&bt1); 194#endif 195 c_func(c_arg); 196#ifdef DIAGNOSTIC 197 binuptime(&bt2); 198 bintime_sub(&bt2, &bt1); 199 if (bt2.frac > maxdt) { 200 bintime2timespec(&bt2, &ts2); 201 printf( 202 "Expensive timeout(9) function: %p(%p) %d.%09d\n", 203 c_func, c_arg, 204 ts2.tv_sec, ts2.tv_nsec); 205 } 206#endif 207 if (!(c_flags & CALLOUT_MPSAFE)) 208 mtx_unlock(&Giant); 209 mtx_lock_spin(&callout_lock); 210 steps = 0; 211 c = nextsoftcheck; 212 } 213 } 214 } 215 nextsoftcheck = NULL; 216 mtx_unlock_spin(&callout_lock); 217} 218 219/* 220 * timeout -- 221 * Execute a function after a specified length of time. 222 * 223 * untimeout -- 224 * Cancel previous timeout function call. 225 * 226 * callout_handle_init -- 227 * Initialize a handle so that using it with untimeout is benign. 228 * 229 * See AT&T BCI Driver Reference Manual for specification. This 230 * implementation differs from that one in that although an 231 * identification value is returned from timeout, the original 232 * arguments to timeout as well as the identifier are used to 233 * identify entries for untimeout. 234 */ 235struct callout_handle 236timeout(ftn, arg, to_ticks) 237 timeout_t *ftn; 238 void *arg; 239 int to_ticks; 240{ 241 struct callout *new; 242 struct callout_handle handle; 243 244 mtx_lock_spin(&callout_lock); 245 246 /* Fill in the next free callout structure. */ 247 new = SLIST_FIRST(&callfree); 248 if (new == NULL) 249 /* XXX Attempt to malloc first */ 250 panic("timeout table full"); 251 SLIST_REMOVE_HEAD(&callfree, c_links.sle); 252 253 callout_reset(new, to_ticks, ftn, arg); 254 255 handle.callout = new; 256 mtx_unlock_spin(&callout_lock); 257 return (handle); 258} 259 260void 261untimeout(ftn, arg, handle) 262 timeout_t *ftn; 263 void *arg; 264 struct callout_handle handle; 265{ 266 267 /* 268 * Check for a handle that was initialized 269 * by callout_handle_init, but never used 270 * for a real timeout. 271 */ 272 if (handle.callout == NULL) 273 return; 274 275 mtx_lock_spin(&callout_lock); 276 if (handle.callout->c_func == ftn && handle.callout->c_arg == arg) 277 callout_stop(handle.callout); 278 mtx_unlock_spin(&callout_lock); 279} 280 281void 282callout_handle_init(struct callout_handle *handle) 283{ 284 handle->callout = NULL; 285} 286 287/* 288 * New interface; clients allocate their own callout structures. 289 * 290 * callout_reset() - establish or change a timeout 291 * callout_stop() - disestablish a timeout 292 * callout_init() - initialize a callout structure so that it can 293 * safely be passed to callout_reset() and callout_stop() 294 * 295 * <sys/callout.h> defines three convenience macros: 296 * 297 * callout_active() - returns truth if callout has not been serviced 298 * callout_pending() - returns truth if callout is still waiting for timeout 299 * callout_deactivate() - marks the callout as having been serviced 300 */ 301void 302callout_reset(c, to_ticks, ftn, arg) 303 struct callout *c; 304 int to_ticks; 305 void (*ftn)(void *); 306 void *arg; 307{ 308 309 mtx_lock_spin(&callout_lock); 310 if (c->c_flags & CALLOUT_PENDING) 311 callout_stop(c); 312 313 /* 314 * We could unlock callout_lock here and lock it again before the 315 * TAILQ_INSERT_TAIL, but there's no point since doing this setup 316 * doesn't take much time. 317 */ 318 if (to_ticks <= 0) 319 to_ticks = 1; 320 321 c->c_arg = arg; 322 c->c_flags |= (CALLOUT_ACTIVE | CALLOUT_PENDING); 323 c->c_func = ftn; 324 c->c_time = ticks + to_ticks; 325 TAILQ_INSERT_TAIL(&callwheel[c->c_time & callwheelmask], 326 c, c_links.tqe); 327 mtx_unlock_spin(&callout_lock); 328} 329 330int 331callout_stop(c) 332 struct callout *c; 333{ 334 335 mtx_lock_spin(&callout_lock); 336 /* 337 * Don't attempt to delete a callout that's not on the queue. 338 */ 339 if (!(c->c_flags & CALLOUT_PENDING)) { 340 c->c_flags &= ~CALLOUT_ACTIVE; 341 mtx_unlock_spin(&callout_lock); 342 return (0); 343 } 344 c->c_flags &= ~(CALLOUT_ACTIVE | CALLOUT_PENDING); 345 346 if (nextsoftcheck == c) { 347 nextsoftcheck = TAILQ_NEXT(c, c_links.tqe); 348 } 349 TAILQ_REMOVE(&callwheel[c->c_time & callwheelmask], c, c_links.tqe); 350 c->c_func = NULL; 351 352 if (c->c_flags & CALLOUT_LOCAL_ALLOC) { 353 SLIST_INSERT_HEAD(&callfree, c, c_links.sle); 354 } 355 mtx_unlock_spin(&callout_lock); 356 return (1); 357} 358 359void 360callout_init(c, mpsafe) 361 struct callout *c; 362 int mpsafe; 363{ 364 bzero(c, sizeof *c); 365 if (mpsafe) 366 c->c_flags |= CALLOUT_MPSAFE; 367} 368 369#ifdef APM_FIXUP_CALLTODO 370/* 371 * Adjust the kernel calltodo timeout list. This routine is used after 372 * an APM resume to recalculate the calltodo timer list values with the 373 * number of hz's we have been sleeping. The next hardclock() will detect 374 * that there are fired timers and run softclock() to execute them. 375 * 376 * Please note, I have not done an exhaustive analysis of what code this 377 * might break. I am motivated to have my select()'s and alarm()'s that 378 * have expired during suspend firing upon resume so that the applications 379 * which set the timer can do the maintanence the timer was for as close 380 * as possible to the originally intended time. Testing this code for a 381 * week showed that resuming from a suspend resulted in 22 to 25 timers 382 * firing, which seemed independant on whether the suspend was 2 hours or 383 * 2 days. Your milage may vary. - Ken Key <key@cs.utk.edu> 384 */ 385void 386adjust_timeout_calltodo(time_change) 387 struct timeval *time_change; 388{ 389 register struct callout *p; 390 unsigned long delta_ticks; 391 392 /* 393 * How many ticks were we asleep? 394 * (stolen from tvtohz()). 395 */ 396 397 /* Don't do anything */ 398 if (time_change->tv_sec < 0) 399 return; 400 else if (time_change->tv_sec <= LONG_MAX / 1000000) 401 delta_ticks = (time_change->tv_sec * 1000000 + 402 time_change->tv_usec + (tick - 1)) / tick + 1; 403 else if (time_change->tv_sec <= LONG_MAX / hz) 404 delta_ticks = time_change->tv_sec * hz + 405 (time_change->tv_usec + (tick - 1)) / tick + 1; 406 else 407 delta_ticks = LONG_MAX; 408 409 if (delta_ticks > INT_MAX) 410 delta_ticks = INT_MAX; 411 412 /* 413 * Now rip through the timer calltodo list looking for timers 414 * to expire. 415 */ 416 417 /* don't collide with softclock() */ 418 mtx_lock_spin(&callout_lock); 419 for (p = calltodo.c_next; p != NULL; p = p->c_next) { 420 p->c_time -= delta_ticks; 421 422 /* Break if the timer had more time on it than delta_ticks */ 423 if (p->c_time > 0) 424 break; 425 426 /* take back the ticks the timer didn't use (p->c_time <= 0) */ 427 delta_ticks = -p->c_time; 428 } 429 mtx_unlock_spin(&callout_lock); 430 431 return; 432} 433#endif /* APM_FIXUP_CALLTODO */ 434