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 * $FreeBSD$ 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 #include <sys/sysctl.h> 49 50 static int avg_depth; 51 SYSCTL_INT(_debug, OID_AUTO, to_avg_depth, CTLFLAG_RD, &avg_depth, 0, 52 "Average number of items examined per softclock call. Units = 1/1000"); 53 static int avg_gcalls; 54 SYSCTL_INT(_debug, OID_AUTO, to_avg_gcalls, CTLFLAG_RD, &avg_gcalls, 0, 55 "Average number of Giant callouts made per softclock call. Units = 1/1000"); 56 static int avg_mpcalls; 57 SYSCTL_INT(_debug, OID_AUTO, to_avg_mpcalls, CTLFLAG_RD, &avg_mpcalls, 0, 58 "Average number of MP callouts made per softclock call. Units = 1/1000"); 59 /* 60 * TODO: 61 * allocate more timeout table slots when table overflows. 62 */ 63 64 /* Exported to machdep.c and/or kern_clock.c. */ 65 struct callout *callout; 66 struct callout_list callfree; 67 int callwheelsize, callwheelbits, callwheelmask; 68 struct callout_tailq *callwheel; 69 int softticks; /* Like ticks, but for softclock(). */ 70 struct mtx callout_lock; 71 72 static struct callout *nextsoftcheck; /* Next callout to be checked. */ 73 74 /* 75 * kern_timeout_callwheel_alloc() - kernel low level callwheel initialization 76 * 77 * This code is called very early in the kernel initialization sequence, 78 * and may be called more then once. 79 */ 80 caddr_t 81 kern_timeout_callwheel_alloc(caddr_t v) 82 { 83 /* 84 * Calculate callout wheel size 85 */ 86 for (callwheelsize = 1, callwheelbits = 0; 87 callwheelsize < ncallout; 88 callwheelsize <<= 1, ++callwheelbits) 89 ; 90 callwheelmask = callwheelsize - 1; 91 92 callout = (struct callout *)v; 93 v = (caddr_t)(callout + ncallout); 94 callwheel = (struct callout_tailq *)v; 95 v = (caddr_t)(callwheel + callwheelsize); 96 return(v); 97 } 98 99 /* 100 * kern_timeout_callwheel_init() - initialize previously reserved callwheel 101 * space. 102 * 103 * This code is called just once, after the space reserved for the 104 * callout wheel has been finalized. 105 */ 106 void 107 kern_timeout_callwheel_init(void) 108 { 109 int i; 110 111 SLIST_INIT(&callfree); 112 for (i = 0; i < ncallout; i++) { 113 callout_init(&callout[i], 0); 114 callout[i].c_flags = CALLOUT_LOCAL_ALLOC; 115 SLIST_INSERT_HEAD(&callfree, &callout[i], c_links.sle); 116 } 117 for (i = 0; i < callwheelsize; i++) { 118 TAILQ_INIT(&callwheel[i]); 119 } 120 mtx_init(&callout_lock, "callout", NULL, MTX_SPIN | MTX_RECURSE); 121 } 122 123 /* 124 * The callout mechanism is based on the work of Adam M. Costello and 125 * George Varghese, published in a technical report entitled "Redesigning 126 * the BSD Callout and Timer Facilities" and modified slightly for inclusion 127 * in FreeBSD by Justin T. Gibbs. The original work on the data structures 128 * used in this implementation was published by G.Varghese and A. Lauck in 129 * the paper "Hashed and Hierarchical Timing Wheels: Data Structures for 130 * the Efficient Implementation of a Timer Facility" in the Proceedings of 131 * the 11th ACM Annual Symposium on Operating Systems Principles, 132 * Austin, Texas Nov 1987. 133 */ 134 135 /* 136 * Software (low priority) clock interrupt. 137 * Run periodic events from timeout queue. 138 */ 139 void 140 softclock(void *dummy) 141 { 142 struct callout *c; 143 struct callout_tailq *bucket; 144 int curticks; 145 int steps; /* #steps since we last allowed interrupts */ 146 int depth; 147 int mpcalls; 148 int gcalls; 149 #ifdef DIAGNOSTIC 150 struct bintime bt1, bt2; 151 struct timespec ts2; 152 static uint64_t maxdt = 18446744073709551LL; /* 1 msec */ 153 #endif 154 155 #ifndef MAX_SOFTCLOCK_STEPS 156 #define MAX_SOFTCLOCK_STEPS 100 /* Maximum allowed value of steps. */ 157 #endif /* MAX_SOFTCLOCK_STEPS */ 158 159 mpcalls = 0; 160 gcalls = 0; 161 depth = 0; 162 steps = 0; 163 mtx_lock_spin(&callout_lock); 164 while (softticks != ticks) { 165 softticks++; 166 /* 167 * softticks may be modified by hard clock, so cache 168 * it while we work on a given bucket. 169 */ 170 curticks = softticks; 171 bucket = &callwheel[curticks & callwheelmask]; 172 c = TAILQ_FIRST(bucket); 173 while (c) { 174 depth++; 175 if (c->c_time != curticks) { 176 c = TAILQ_NEXT(c, c_links.tqe); 177 ++steps; 178 if (steps >= MAX_SOFTCLOCK_STEPS) { 179 nextsoftcheck = c; 180 /* Give interrupts a chance. */ 181 mtx_unlock_spin(&callout_lock); 182 ; /* nothing */ 183 mtx_lock_spin(&callout_lock); 184 c = nextsoftcheck; 185 steps = 0; 186 } 187 } else { 188 void (*c_func)(void *); 189 void *c_arg; 190 int c_flags; 191 192 nextsoftcheck = TAILQ_NEXT(c, c_links.tqe); 193 TAILQ_REMOVE(bucket, c, c_links.tqe); 194 c_func = c->c_func; 195 c_arg = c->c_arg; 196 c_flags = c->c_flags; 197 c->c_func = NULL; 198 if (c->c_flags & CALLOUT_LOCAL_ALLOC) { 199 c->c_flags = CALLOUT_LOCAL_ALLOC; 200 SLIST_INSERT_HEAD(&callfree, c, 201 c_links.sle); 202 } else { 203 c->c_flags = 204 (c->c_flags & ~CALLOUT_PENDING); 205 } 206 mtx_unlock_spin(&callout_lock); 207 if (!(c_flags & CALLOUT_MPSAFE)) { 208 mtx_lock(&Giant); 209 gcalls++; 210 } else { 211 mpcalls++; 212 } 213 #ifdef DIAGNOSTIC 214 binuptime(&bt1); 215 #endif 216 c_func(c_arg); 217 #ifdef DIAGNOSTIC 218 binuptime(&bt2); 219 bintime_sub(&bt2, &bt1); 220 if (bt2.frac > maxdt) { 221 maxdt = bt2.frac; 222 bintime2timespec(&bt2, &ts2); 223 printf( 224 "Expensive timeout(9) function: %p(%p) %d.%09ld s\n", 225 c_func, c_arg, 226 ts2.tv_sec, ts2.tv_nsec); 227 } 228 #endif 229 if (!(c_flags & CALLOUT_MPSAFE)) 230 mtx_unlock(&Giant); 231 mtx_lock_spin(&callout_lock); 232 steps = 0; 233 c = nextsoftcheck; 234 } 235 } 236 } 237 avg_depth += (depth * 1000 - avg_depth) >> 8; 238 avg_mpcalls += (mpcalls * 1000 - avg_mpcalls) >> 8; 239 avg_gcalls += (gcalls * 1000 - avg_gcalls) >> 8; 240 nextsoftcheck = NULL; 241 mtx_unlock_spin(&callout_lock); 242 } 243 244 /* 245 * timeout -- 246 * Execute a function after a specified length of time. 247 * 248 * untimeout -- 249 * Cancel previous timeout function call. 250 * 251 * callout_handle_init -- 252 * Initialize a handle so that using it with untimeout is benign. 253 * 254 * See AT&T BCI Driver Reference Manual for specification. This 255 * implementation differs from that one in that although an 256 * identification value is returned from timeout, the original 257 * arguments to timeout as well as the identifier are used to 258 * identify entries for untimeout. 259 */ 260 struct callout_handle 261 timeout(ftn, arg, to_ticks) 262 timeout_t *ftn; 263 void *arg; 264 int to_ticks; 265 { 266 struct callout *new; 267 struct callout_handle handle; 268 269 mtx_lock_spin(&callout_lock); 270 271 /* Fill in the next free callout structure. */ 272 new = SLIST_FIRST(&callfree); 273 if (new == NULL) 274 /* XXX Attempt to malloc first */ 275 panic("timeout table full"); 276 SLIST_REMOVE_HEAD(&callfree, c_links.sle); 277 278 callout_reset(new, to_ticks, ftn, arg); 279 280 handle.callout = new; 281 mtx_unlock_spin(&callout_lock); 282 return (handle); 283 } 284 285 void 286 untimeout(ftn, arg, handle) 287 timeout_t *ftn; 288 void *arg; 289 struct callout_handle handle; 290 { 291 292 /* 293 * Check for a handle that was initialized 294 * by callout_handle_init, but never used 295 * for a real timeout. 296 */ 297 if (handle.callout == NULL) 298 return; 299 300 mtx_lock_spin(&callout_lock); 301 if (handle.callout->c_func == ftn && handle.callout->c_arg == arg) 302 callout_stop(handle.callout); 303 mtx_unlock_spin(&callout_lock); 304 } 305 306 void 307 callout_handle_init(struct callout_handle *handle) 308 { 309 handle->callout = NULL; 310 } 311 312 /* 313 * New interface; clients allocate their own callout structures. 314 * 315 * callout_reset() - establish or change a timeout 316 * callout_stop() - disestablish a timeout 317 * callout_init() - initialize a callout structure so that it can 318 * safely be passed to callout_reset() and callout_stop() 319 * 320 * <sys/callout.h> defines three convenience macros: 321 * 322 * callout_active() - returns truth if callout has not been serviced 323 * callout_pending() - returns truth if callout is still waiting for timeout 324 * callout_deactivate() - marks the callout as having been serviced 325 */ 326 void 327 callout_reset(c, to_ticks, ftn, arg) 328 struct callout *c; 329 int to_ticks; 330 void (*ftn)(void *); 331 void *arg; 332 { 333 334 mtx_lock_spin(&callout_lock); 335 if (c->c_flags & CALLOUT_PENDING) 336 callout_stop(c); 337 338 /* 339 * We could unlock callout_lock here and lock it again before the 340 * TAILQ_INSERT_TAIL, but there's no point since doing this setup 341 * doesn't take much time. 342 */ 343 if (to_ticks <= 0) 344 to_ticks = 1; 345 346 c->c_arg = arg; 347 c->c_flags |= (CALLOUT_ACTIVE | CALLOUT_PENDING); 348 c->c_func = ftn; 349 c->c_time = ticks + to_ticks; 350 TAILQ_INSERT_TAIL(&callwheel[c->c_time & callwheelmask], 351 c, c_links.tqe); 352 mtx_unlock_spin(&callout_lock); 353 } 354 355 int 356 callout_stop(c) 357 struct callout *c; 358 { 359 360 mtx_lock_spin(&callout_lock); 361 /* 362 * Don't attempt to delete a callout that's not on the queue. 363 */ 364 if (!(c->c_flags & CALLOUT_PENDING)) { 365 c->c_flags &= ~CALLOUT_ACTIVE; 366 mtx_unlock_spin(&callout_lock); 367 return (0); 368 } 369 c->c_flags &= ~(CALLOUT_ACTIVE | CALLOUT_PENDING); 370 371 if (nextsoftcheck == c) { 372 nextsoftcheck = TAILQ_NEXT(c, c_links.tqe); 373 } 374 TAILQ_REMOVE(&callwheel[c->c_time & callwheelmask], c, c_links.tqe); 375 c->c_func = NULL; 376 377 if (c->c_flags & CALLOUT_LOCAL_ALLOC) { 378 SLIST_INSERT_HEAD(&callfree, c, c_links.sle); 379 } 380 mtx_unlock_spin(&callout_lock); 381 return (1); 382 } 383 384 void 385 callout_init(c, mpsafe) 386 struct callout *c; 387 int mpsafe; 388 { 389 bzero(c, sizeof *c); 390 if (mpsafe) 391 c->c_flags |= CALLOUT_MPSAFE; 392 } 393 394 #ifdef APM_FIXUP_CALLTODO 395 /* 396 * Adjust the kernel calltodo timeout list. This routine is used after 397 * an APM resume to recalculate the calltodo timer list values with the 398 * number of hz's we have been sleeping. The next hardclock() will detect 399 * that there are fired timers and run softclock() to execute them. 400 * 401 * Please note, I have not done an exhaustive analysis of what code this 402 * might break. I am motivated to have my select()'s and alarm()'s that 403 * have expired during suspend firing upon resume so that the applications 404 * which set the timer can do the maintanence the timer was for as close 405 * as possible to the originally intended time. Testing this code for a 406 * week showed that resuming from a suspend resulted in 22 to 25 timers 407 * firing, which seemed independant on whether the suspend was 2 hours or 408 * 2 days. Your milage may vary. - Ken Key <key@cs.utk.edu> 409 */ 410 void 411 adjust_timeout_calltodo(time_change) 412 struct timeval *time_change; 413 { 414 register struct callout *p; 415 unsigned long delta_ticks; 416 417 /* 418 * How many ticks were we asleep? 419 * (stolen from tvtohz()). 420 */ 421 422 /* Don't do anything */ 423 if (time_change->tv_sec < 0) 424 return; 425 else if (time_change->tv_sec <= LONG_MAX / 1000000) 426 delta_ticks = (time_change->tv_sec * 1000000 + 427 time_change->tv_usec + (tick - 1)) / tick + 1; 428 else if (time_change->tv_sec <= LONG_MAX / hz) 429 delta_ticks = time_change->tv_sec * hz + 430 (time_change->tv_usec + (tick - 1)) / tick + 1; 431 else 432 delta_ticks = LONG_MAX; 433 434 if (delta_ticks > INT_MAX) 435 delta_ticks = INT_MAX; 436 437 /* 438 * Now rip through the timer calltodo list looking for timers 439 * to expire. 440 */ 441 442 /* don't collide with softclock() */ 443 mtx_lock_spin(&callout_lock); 444 for (p = calltodo.c_next; p != NULL; p = p->c_next) { 445 p->c_time -= delta_ticks; 446 447 /* Break if the timer had more time on it than delta_ticks */ 448 if (p->c_time > 0) 449 break; 450 451 /* take back the ticks the timer didn't use (p->c_time <= 0) */ 452 delta_ticks = -p->c_time; 453 } 454 mtx_unlock_spin(&callout_lock); 455 456 return; 457 } 458 #endif /* APM_FIXUP_CALLTODO */ 459