kern_timeout.c revision 1.6.2.3
1 /* $NetBSD: kern_timeout.c,v 1.6.2.3 2004/09/21 13:35:11 skrll Exp $ */ 2 3 /*- 4 * Copyright (c) 2003 The NetBSD Foundation, Inc. 5 * All rights reserved. 6 * 7 * This code is derived from software contributed to The NetBSD Foundation 8 * by Jason R. Thorpe. 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 NetBSD 21 * Foundation, Inc. and its contributors. 22 * 4. Neither the name of The NetBSD Foundation nor the names of its 23 * contributors may be used to endorse or promote products derived 24 * from this software without specific prior written permission. 25 * 26 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 27 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 28 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 29 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 30 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 31 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 32 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 33 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 34 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 35 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 36 * POSSIBILITY OF SUCH DAMAGE. 37 */ 38 39 /* 40 * Copyright (c) 2001 Thomas Nordin <nordin (at) openbsd.org> 41 * Copyright (c) 2000-2001 Artur Grabowski <art (at) openbsd.org> 42 * All rights reserved. 43 * 44 * Redistribution and use in source and binary forms, with or without 45 * modification, are permitted provided that the following conditions 46 * are met: 47 * 48 * 1. Redistributions of source code must retain the above copyright 49 * notice, this list of conditions and the following disclaimer. 50 * 2. Redistributions in binary form must reproduce the above copyright 51 * notice, this list of conditions and the following disclaimer in the 52 * documentation and/or other materials provided with the distribution. 53 * 3. The name of the author may not be used to endorse or promote products 54 * derived from this software without specific prior written permission. 55 * 56 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, 57 * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY 58 * AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL 59 * THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, 60 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, 61 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; 62 * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, 63 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR 64 * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF 65 * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 66 */ 67 68 #include <sys/cdefs.h> 69 __KERNEL_RCSID(0, "$NetBSD: kern_timeout.c,v 1.6.2.3 2004/09/21 13:35:11 skrll Exp $"); 70 71 /* 72 * Adapted from OpenBSD: kern_timeout.c,v 1.15 2002/12/08 04:21:07 art Exp, 73 * modified to match NetBSD's pre-existing callout API. 74 */ 75 76 #include <sys/param.h> 77 #include <sys/systm.h> 78 #include <sys/kernel.h> 79 #include <sys/lock.h> 80 #include <sys/callout.h> 81 82 #ifdef DDB 83 #include <machine/db_machdep.h> 84 #include <ddb/db_interface.h> 85 #include <ddb/db_access.h> 86 #include <ddb/db_sym.h> 87 #include <ddb/db_output.h> 88 #endif 89 90 /* 91 * Timeouts are kept in a hierarchical timing wheel. The c_time is the value 92 * of the global variable "hardclock_ticks" when the timeout should be called. 93 * There are four levels with 256 buckets each. See 'Scheme 7' in 94 * "Hashed and Hierarchical Timing Wheels: Efficient Data Structures for 95 * Implementing a Timer Facility" by George Varghese and Tony Lauck. 96 */ 97 #define BUCKETS 1024 98 #define WHEELSIZE 256 99 #define WHEELMASK 255 100 #define WHEELBITS 8 101 102 static struct callout_circq timeout_wheel[BUCKETS]; /* Queues of timeouts */ 103 static struct callout_circq timeout_todo; /* Worklist */ 104 105 #define MASKWHEEL(wheel, time) (((time) >> ((wheel)*WHEELBITS)) & WHEELMASK) 106 107 #define BUCKET(rel, abs) \ 108 (((rel) <= (1 << (2*WHEELBITS))) \ 109 ? ((rel) <= (1 << WHEELBITS)) \ 110 ? &timeout_wheel[MASKWHEEL(0, (abs))] \ 111 : &timeout_wheel[MASKWHEEL(1, (abs)) + WHEELSIZE] \ 112 : ((rel) <= (1 << (3*WHEELBITS))) \ 113 ? &timeout_wheel[MASKWHEEL(2, (abs)) + 2*WHEELSIZE] \ 114 : &timeout_wheel[MASKWHEEL(3, (abs)) + 3*WHEELSIZE]) 115 116 #define MOVEBUCKET(wheel, time) \ 117 CIRCQ_APPEND(&timeout_todo, \ 118 &timeout_wheel[MASKWHEEL((wheel), (time)) + (wheel)*WHEELSIZE]) 119 120 /* 121 * All wheels are locked with the same lock (which must also block out all 122 * interrupts). 123 */ 124 static struct simplelock callout_slock; 125 126 #define CALLOUT_LOCK(s) \ 127 do { \ 128 s = splsched(); \ 129 simple_lock(&callout_slock); \ 130 } while (/*CONSTCOND*/0) 131 132 #define CALLOUT_UNLOCK(s) \ 133 do { \ 134 simple_unlock(&callout_slock); \ 135 splx((s)); \ 136 } while (/*CONSTCOND*/0) 137 138 /* 139 * Circular queue definitions. 140 */ 141 142 #define CIRCQ_INIT(list) \ 143 do { \ 144 (list)->cq_next_l = (list); \ 145 (list)->cq_prev_l = (list); \ 146 } while (/*CONSTCOND*/0) 147 148 #define CIRCQ_INSERT(elem, list) \ 149 do { \ 150 (elem)->cq_prev_e = (list)->cq_prev_e; \ 151 (elem)->cq_next_l = (list); \ 152 (list)->cq_prev_l->cq_next_l = (elem); \ 153 (list)->cq_prev_l = (elem); \ 154 } while (/*CONSTCOND*/0) 155 156 #define CIRCQ_APPEND(fst, snd) \ 157 do { \ 158 if (!CIRCQ_EMPTY(snd)) { \ 159 (fst)->cq_prev_l->cq_next_l = (snd)->cq_next_l; \ 160 (snd)->cq_next_l->cq_prev_l = (fst)->cq_prev_l; \ 161 (snd)->cq_prev_l->cq_next_l = (fst); \ 162 (fst)->cq_prev_l = (snd)->cq_prev_l; \ 163 CIRCQ_INIT(snd); \ 164 } \ 165 } while (/*CONSTCOND*/0) 166 167 #define CIRCQ_REMOVE(elem) \ 168 do { \ 169 (elem)->cq_next_l->cq_prev_e = (elem)->cq_prev_e; \ 170 (elem)->cq_prev_l->cq_next_e = (elem)->cq_next_e; \ 171 } while (/*CONSTCOND*/0) 172 173 #define CIRCQ_FIRST(list) ((list)->cq_next_e) 174 #define CIRCQ_NEXT(elem) ((elem)->cq_next_e) 175 #define CIRCQ_LAST(elem,list) ((elem)->cq_next_l == (list)) 176 #define CIRCQ_EMPTY(list) ((list)->cq_next_l == (list)) 177 178 /* 179 * Some of the "math" in here is a bit tricky. 180 * 181 * We have to beware of wrapping ints. 182 * We use the fact that any element added to the queue must be added with a 183 * positive time. That means that any element `to' on the queue cannot be 184 * scheduled to timeout further in time than INT_MAX, but c->c_time can 185 * be positive or negative so comparing it with anything is dangerous. 186 * The only way we can use the c->c_time value in any predictable way 187 * is when we calculate how far in the future `to' will timeout - 188 * "c->c_time - hardclock_ticks". The result will always be positive for 189 * future timeouts and 0 or negative for due timeouts. 190 */ 191 192 #ifdef CALLOUT_EVENT_COUNTERS 193 static struct evcnt callout_ev_late; 194 #endif 195 196 /* 197 * callout_startup: 198 * 199 * Initialize the callout facility, called at system startup time. 200 */ 201 void 202 callout_startup(void) 203 { 204 int b; 205 206 CIRCQ_INIT(&timeout_todo); 207 for (b = 0; b < BUCKETS; b++) 208 CIRCQ_INIT(&timeout_wheel[b]); 209 simple_lock_init(&callout_slock); 210 211 #ifdef CALLOUT_EVENT_COUNTERS 212 evcnt_attach_dynamic(&callout_ev_late, EVCNT_TYPE_MISC, 213 NULL, "callout", "late"); 214 #endif 215 } 216 217 /* 218 * callout_init: 219 * 220 * Initialize a callout structure. 221 */ 222 void 223 callout_init(struct callout *c) 224 { 225 226 memset(c, 0, sizeof(*c)); 227 } 228 229 /* 230 * callout_reset: 231 * 232 * Reset a callout structure with a new function and argument, and 233 * schedule it to run. 234 */ 235 void 236 callout_reset(struct callout *c, int to_ticks, void (*func)(void *), void *arg) 237 { 238 int s, old_time; 239 240 KASSERT(to_ticks >= 0); 241 242 CALLOUT_LOCK(s); 243 244 /* Initialize the time here, it won't change. */ 245 old_time = c->c_time; 246 c->c_time = to_ticks + hardclock_ticks; 247 c->c_flags &= ~(CALLOUT_FIRED|CALLOUT_INVOKING); 248 249 c->c_func = func; 250 c->c_arg = arg; 251 252 /* 253 * If this timeout is already scheduled and now is moved 254 * earlier, reschedule it now. Otherwise leave it in place 255 * and let it be rescheduled later. 256 */ 257 if (callout_pending(c)) { 258 if (c->c_time - old_time < 0) { 259 CIRCQ_REMOVE(&c->c_list); 260 CIRCQ_INSERT(&c->c_list, &timeout_todo); 261 } 262 } else { 263 c->c_flags |= CALLOUT_PENDING; 264 CIRCQ_INSERT(&c->c_list, &timeout_todo); 265 } 266 267 CALLOUT_UNLOCK(s); 268 } 269 270 /* 271 * callout_schedule: 272 * 273 * Schedule a callout to run. The function and argument must 274 * already be set in the callout structure. 275 */ 276 void 277 callout_schedule(struct callout *c, int to_ticks) 278 { 279 int s, old_time; 280 281 KASSERT(to_ticks >= 0); 282 283 CALLOUT_LOCK(s); 284 285 /* Initialize the time here, it won't change. */ 286 old_time = c->c_time; 287 c->c_time = to_ticks + hardclock_ticks; 288 c->c_flags &= ~(CALLOUT_FIRED|CALLOUT_INVOKING); 289 290 /* 291 * If this timeout is already scheduled and now is moved 292 * earlier, reschedule it now. Otherwise leave it in place 293 * and let it be rescheduled later. 294 */ 295 if (callout_pending(c)) { 296 if (c->c_time - old_time < 0) { 297 CIRCQ_REMOVE(&c->c_list); 298 CIRCQ_INSERT(&c->c_list, &timeout_todo); 299 } 300 } else { 301 c->c_flags |= CALLOUT_PENDING; 302 CIRCQ_INSERT(&c->c_list, &timeout_todo); 303 } 304 305 CALLOUT_UNLOCK(s); 306 } 307 308 /* 309 * callout_stop: 310 * 311 * Cancel a pending callout. 312 */ 313 void 314 callout_stop(struct callout *c) 315 { 316 int s; 317 318 CALLOUT_LOCK(s); 319 320 if (callout_pending(c)) 321 CIRCQ_REMOVE(&c->c_list); 322 323 c->c_flags &= ~(CALLOUT_PENDING|CALLOUT_FIRED); 324 325 CALLOUT_UNLOCK(s); 326 } 327 328 /* 329 * This is called from hardclock() once every tick. 330 * We return !0 if we need to schedule a softclock. 331 */ 332 int 333 callout_hardclock(void) 334 { 335 int s; 336 int needsoftclock; 337 338 CALLOUT_LOCK(s); 339 340 MOVEBUCKET(0, hardclock_ticks); 341 if (MASKWHEEL(0, hardclock_ticks) == 0) { 342 MOVEBUCKET(1, hardclock_ticks); 343 if (MASKWHEEL(1, hardclock_ticks) == 0) { 344 MOVEBUCKET(2, hardclock_ticks); 345 if (MASKWHEEL(2, hardclock_ticks) == 0) 346 MOVEBUCKET(3, hardclock_ticks); 347 } 348 } 349 350 needsoftclock = !CIRCQ_EMPTY(&timeout_todo); 351 CALLOUT_UNLOCK(s); 352 353 return needsoftclock; 354 } 355 356 /* ARGSUSED */ 357 void 358 softclock(void *v) 359 { 360 struct callout *c; 361 void (*func)(void *); 362 void *arg; 363 int s; 364 365 CALLOUT_LOCK(s); 366 367 while (!CIRCQ_EMPTY(&timeout_todo)) { 368 c = CIRCQ_FIRST(&timeout_todo); 369 CIRCQ_REMOVE(&c->c_list); 370 371 /* If due run it, otherwise insert it into the right bucket. */ 372 if (c->c_time - hardclock_ticks > 0) { 373 CIRCQ_INSERT(&c->c_list, 374 BUCKET((c->c_time - hardclock_ticks), c->c_time)); 375 } else { 376 #ifdef CALLOUT_EVENT_COUNTERS 377 if (c->c_time - hardclock_ticks < 0) 378 callout_ev_late.ev_count++; 379 #endif 380 c->c_flags = (c->c_flags & ~CALLOUT_PENDING) | 381 (CALLOUT_FIRED|CALLOUT_INVOKING); 382 383 func = c->c_func; 384 arg = c->c_arg; 385 386 CALLOUT_UNLOCK(s); 387 (*func)(arg); 388 CALLOUT_LOCK(s); 389 } 390 } 391 392 CALLOUT_UNLOCK(s); 393 } 394 395 #ifdef DDB 396 static void 397 db_show_callout_bucket(struct callout_circq *bucket) 398 { 399 struct callout *c; 400 db_expr_t offset; 401 char *name; 402 403 if (CIRCQ_EMPTY(bucket)) 404 return; 405 406 for (c = CIRCQ_FIRST(bucket); /*nothing*/; c = CIRCQ_NEXT(&c->c_list)) { 407 db_find_sym_and_offset((db_addr_t)(intptr_t)c->c_func, &name, 408 &offset); 409 name = name ? name : "?"; 410 #ifdef _LP64 411 #define POINTER_WIDTH "%16lx" 412 #else 413 #define POINTER_WIDTH "%8lx" 414 #endif 415 db_printf("%9d %2d/%-4d " POINTER_WIDTH " %s\n", 416 c->c_time - hardclock_ticks, 417 (int)((bucket - timeout_wheel) / WHEELSIZE), 418 (int)(bucket - timeout_wheel), (u_long) c->c_arg, name); 419 420 if (CIRCQ_LAST(&c->c_list, bucket)) 421 break; 422 } 423 } 424 425 void 426 db_show_callout(db_expr_t addr, int haddr, db_expr_t count, char *modif) 427 { 428 int b; 429 430 db_printf("hardclock_ticks now: %d\n", hardclock_ticks); 431 #ifdef _LP64 432 db_printf(" ticks wheel arg func\n"); 433 #else 434 db_printf(" ticks wheel arg func\n"); 435 #endif 436 437 /* 438 * Don't lock the callwheel; all the other CPUs are paused 439 * anyhow, and we might be called in a circumstance where 440 * some other CPU was paused while holding the lock. 441 */ 442 443 db_show_callout_bucket(&timeout_todo); 444 for (b = 0; b < BUCKETS; b++) 445 db_show_callout_bucket(&timeout_wheel[b]); 446 } 447 #endif /* DDB */ 448
Indexes created Sat Sep 20 22:09:52 GMT 2025