kern_timeout.c revision 1.6
1 /* $NetBSD: kern_timeout.c,v 1.6 2003/05/17 15:53:42 mjl 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 /* 69 * Adapted from OpenBSD: kern_timeout.c,v 1.15 2002/12/08 04:21:07 art Exp, 70 * modified to match NetBSD's pre-existing callout API. 71 */ 72 73 #include <sys/param.h> 74 #include <sys/systm.h> 75 #include <sys/kernel.h> 76 #include <sys/lock.h> 77 #include <sys/callout.h> 78 79 #ifdef DDB 80 #include <machine/db_machdep.h> 81 #include <ddb/db_interface.h> 82 #include <ddb/db_access.h> 83 #include <ddb/db_sym.h> 84 #include <ddb/db_output.h> 85 #endif 86 87 /* 88 * Timeouts are kept in a hierarchical timing wheel. The c_time is the value 89 * of the global variable "hardclock_ticks" when the timeout should be called. 90 * There are four levels with 256 buckets each. See 'Scheme 7' in 91 * "Hashed and Hierarchical Timing Wheels: Efficient Data Structures for 92 * Implementing a Timer Facility" by George Varghese and Tony Lauck. 93 */ 94 #define BUCKETS 1024 95 #define WHEELSIZE 256 96 #define WHEELMASK 255 97 #define WHEELBITS 8 98 99 static struct callout_circq timeout_wheel[BUCKETS]; /* Queues of timeouts */ 100 static struct callout_circq timeout_todo; /* Worklist */ 101 102 #define MASKWHEEL(wheel, time) (((time) >> ((wheel)*WHEELBITS)) & WHEELMASK) 103 104 #define BUCKET(rel, abs) \ 105 (((rel) <= (1 << (2*WHEELBITS))) \ 106 ? ((rel) <= (1 << WHEELBITS)) \ 107 ? &timeout_wheel[MASKWHEEL(0, (abs))] \ 108 : &timeout_wheel[MASKWHEEL(1, (abs)) + WHEELSIZE] \ 109 : ((rel) <= (1 << (3*WHEELBITS))) \ 110 ? &timeout_wheel[MASKWHEEL(2, (abs)) + 2*WHEELSIZE] \ 111 : &timeout_wheel[MASKWHEEL(3, (abs)) + 3*WHEELSIZE]) 112 113 #define MOVEBUCKET(wheel, time) \ 114 CIRCQ_APPEND(&timeout_todo, \ 115 &timeout_wheel[MASKWHEEL((wheel), (time)) + (wheel)*WHEELSIZE]) 116 117 /* 118 * All wheels are locked with the same lock (which must also block out all 119 * interrupts). 120 */ 121 static struct simplelock callout_slock; 122 123 #define CALLOUT_LOCK(s) \ 124 do { \ 125 s = splsched(); \ 126 simple_lock(&callout_slock); \ 127 } while (/*CONSTCOND*/0) 128 129 #define CALLOUT_UNLOCK(s) \ 130 do { \ 131 simple_unlock(&callout_slock); \ 132 splx((s)); \ 133 } while (/*CONSTCOND*/0) 134 135 /* 136 * Circular queue definitions. 137 */ 138 139 #define CIRCQ_INIT(elem) \ 140 do { \ 141 (elem)->cq_next = (elem); \ 142 (elem)->cq_prev = (elem); \ 143 } while (/*CONSTCOND*/0) 144 145 #define CIRCQ_INSERT(elem, list) \ 146 do { \ 147 (elem)->cq_prev = (list)->cq_prev; \ 148 (elem)->cq_next = (list); \ 149 (list)->cq_prev->cq_next = (elem); \ 150 (list)->cq_prev = (elem); \ 151 } while (/*CONSTCOND*/0) 152 153 #define CIRCQ_APPEND(fst, snd) \ 154 do { \ 155 if (!CIRCQ_EMPTY(snd)) { \ 156 (fst)->cq_prev->cq_next = (snd)->cq_next; \ 157 (snd)->cq_next->cq_prev = (fst)->cq_prev; \ 158 (snd)->cq_prev->cq_next = (fst); \ 159 (fst)->cq_prev = (snd)->cq_prev; \ 160 CIRCQ_INIT(snd); \ 161 } \ 162 } while (/*CONSTCOND*/0) 163 164 #define CIRCQ_REMOVE(elem) \ 165 do { \ 166 (elem)->cq_next->cq_prev = (elem)->cq_prev; \ 167 (elem)->cq_prev->cq_next = (elem)->cq_next; \ 168 } while (/*CONSTCOND*/0) 169 170 #define CIRCQ_FIRST(elem) ((elem)->cq_next) 171 172 #define CIRCQ_EMPTY(elem) (CIRCQ_FIRST(elem) == (elem)) 173 174 /* 175 * Some of the "math" in here is a bit tricky. 176 * 177 * We have to beware of wrapping ints. 178 * We use the fact that any element added to the queue must be added with a 179 * positive time. That means that any element `to' on the queue cannot be 180 * scheduled to timeout further in time than INT_MAX, but c->c_time can 181 * be positive or negative so comparing it with anything is dangerous. 182 * The only way we can use the c->c_time value in any predictable way 183 * is when we calculate how far in the future `to' will timeout - 184 * "c->c_time - hardclock_ticks". The result will always be positive for 185 * future timeouts and 0 or negative for due timeouts. 186 */ 187 188 #ifdef CALLOUT_EVENT_COUNTERS 189 static struct evcnt callout_ev_late; 190 #endif 191 192 /* 193 * callout_startup: 194 * 195 * Initialize the callout facility, called at system startup time. 196 */ 197 void 198 callout_startup(void) 199 { 200 int b; 201 202 CIRCQ_INIT(&timeout_todo); 203 for (b = 0; b < BUCKETS; b++) 204 CIRCQ_INIT(&timeout_wheel[b]); 205 simple_lock_init(&callout_slock); 206 207 #ifdef CALLOUT_EVENT_COUNTERS 208 evcnt_attach_dynamic(&callout_ev_late, EVCNT_TYPE_MISC, 209 NULL, "callout", "late"); 210 #endif 211 } 212 213 /* 214 * callout_init: 215 * 216 * Initialize a callout structure. 217 */ 218 void 219 callout_init(struct callout *c) 220 { 221 222 memset(c, 0, sizeof(*c)); 223 } 224 225 /* 226 * callout_setfunc: 227 * 228 * Initialize a callout structure and set the function and 229 * argument. 230 */ 231 void 232 callout_setfunc(struct callout *c, void (*func)(void *), void *arg) 233 { 234 235 memset(c, 0, sizeof(*c)); 236 c->c_func = func; 237 c->c_arg = arg; 238 } 239 240 /* 241 * callout_reset: 242 * 243 * Reset a callout structure with a new function and argument, and 244 * schedule it to run. 245 */ 246 void 247 callout_reset(struct callout *c, int to_ticks, void (*func)(void *), void *arg) 248 { 249 int s, old_time; 250 251 KASSERT(to_ticks >= 0); 252 253 CALLOUT_LOCK(s); 254 255 /* Initialize the time here, it won't change. */ 256 old_time = c->c_time; 257 c->c_time = to_ticks + hardclock_ticks; 258 c->c_flags &= ~CALLOUT_FIRED; 259 260 c->c_func = func; 261 c->c_arg = arg; 262 263 /* 264 * If this timeout is already scheduled and now is moved 265 * earlier, reschedule it now. Otherwise leave it in place 266 * and let it be rescheduled later. 267 */ 268 if (callout_pending(c)) { 269 if (c->c_time - old_time < 0) { 270 CIRCQ_REMOVE(&c->c_list); 271 CIRCQ_INSERT(&c->c_list, &timeout_todo); 272 } 273 } else { 274 c->c_flags |= CALLOUT_PENDING; 275 CIRCQ_INSERT(&c->c_list, &timeout_todo); 276 } 277 278 CALLOUT_UNLOCK(s); 279 } 280 281 /* 282 * callout_schedule: 283 * 284 * Schedule a callout to run. The function and argument must 285 * already be set in the callout structure. 286 */ 287 void 288 callout_schedule(struct callout *c, int to_ticks) 289 { 290 int s, old_time; 291 292 KASSERT(to_ticks >= 0); 293 294 CALLOUT_LOCK(s); 295 296 /* Initialize the time here, it won't change. */ 297 old_time = c->c_time; 298 c->c_time = to_ticks + hardclock_ticks; 299 c->c_flags &= ~CALLOUT_FIRED; 300 301 /* 302 * If this timeout is already scheduled and now is moved 303 * earlier, reschedule it now. Otherwise leave it in place 304 * and let it be rescheduled later. 305 */ 306 if (callout_pending(c)) { 307 if (c->c_time - old_time < 0) { 308 CIRCQ_REMOVE(&c->c_list); 309 CIRCQ_INSERT(&c->c_list, &timeout_todo); 310 } 311 } else { 312 c->c_flags |= CALLOUT_PENDING; 313 CIRCQ_INSERT(&c->c_list, &timeout_todo); 314 } 315 316 CALLOUT_UNLOCK(s); 317 } 318 319 /* 320 * callout_stop: 321 * 322 * Cancel a pending callout. 323 */ 324 void 325 callout_stop(struct callout *c) 326 { 327 int s; 328 329 CALLOUT_LOCK(s); 330 331 if (callout_pending(c)) 332 CIRCQ_REMOVE(&c->c_list); 333 334 c->c_flags &= ~(CALLOUT_PENDING|CALLOUT_FIRED); 335 336 CALLOUT_UNLOCK(s); 337 } 338 339 /* 340 * This is called from hardclock() once every tick. 341 * We return !0 if we need to schedule a softclock. 342 */ 343 int 344 callout_hardclock(void) 345 { 346 int s; 347 int needsoftclock; 348 349 CALLOUT_LOCK(s); 350 351 MOVEBUCKET(0, hardclock_ticks); 352 if (MASKWHEEL(0, hardclock_ticks) == 0) { 353 MOVEBUCKET(1, hardclock_ticks); 354 if (MASKWHEEL(1, hardclock_ticks) == 0) { 355 MOVEBUCKET(2, hardclock_ticks); 356 if (MASKWHEEL(2, hardclock_ticks) == 0) 357 MOVEBUCKET(3, hardclock_ticks); 358 } 359 } 360 361 needsoftclock = !CIRCQ_EMPTY(&timeout_todo); 362 CALLOUT_UNLOCK(s); 363 364 return needsoftclock; 365 } 366 367 /* ARGSUSED */ 368 void 369 softclock(void *v) 370 { 371 struct callout *c; 372 void (*func)(void *); 373 void *arg; 374 int s; 375 376 CALLOUT_LOCK(s); 377 378 while (!CIRCQ_EMPTY(&timeout_todo)) { 379 380 c = (struct callout *)CIRCQ_FIRST(&timeout_todo); /* XXX */ 381 CIRCQ_REMOVE(&c->c_list); 382 383 /* If due run it, otherwise insert it into the right bucket. */ 384 if (c->c_time - hardclock_ticks > 0) { 385 CIRCQ_INSERT(&c->c_list, 386 BUCKET((c->c_time - hardclock_ticks), c->c_time)); 387 } else { 388 #ifdef CALLOUT_EVENT_COUNTERS 389 if (c->c_time - hardclock_ticks < 0) 390 callout_ev_late.ev_count++; 391 #endif 392 c->c_flags = (c->c_flags & ~CALLOUT_PENDING) | 393 CALLOUT_FIRED; 394 395 func = c->c_func; 396 arg = c->c_arg; 397 398 CALLOUT_UNLOCK(s); 399 (*func)(arg); 400 CALLOUT_LOCK(s); 401 } 402 } 403 404 CALLOUT_UNLOCK(s); 405 } 406 407 #ifdef DDB 408 static void 409 db_show_callout_bucket(struct callout_circq *bucket) 410 { 411 struct callout *c; 412 struct callout_circq *p; 413 db_expr_t offset; 414 char *name; 415 416 for (p = CIRCQ_FIRST(bucket); p != bucket; p = CIRCQ_FIRST(p)) { 417 c = (struct callout *)p; /* XXX */ 418 db_find_sym_and_offset((db_addr_t)c->c_func, &name, &offset); 419 name = name ? name : "?"; 420 #ifdef _LP64 421 #define POINTER_WIDTH "%16lx" 422 #else 423 #define POINTER_WIDTH "%8lx" 424 #endif 425 db_printf("%9d %2d/%-4d " POINTER_WIDTH " %s\n", 426 c->c_time - hardclock_ticks, 427 (int)((bucket - timeout_wheel) / WHEELSIZE), 428 (int)(bucket - timeout_wheel), (u_long) c->c_arg, name); 429 } 430 } 431 432 void 433 db_show_callout(db_expr_t addr, int haddr, db_expr_t count, char *modif) 434 { 435 int b; 436 437 db_printf("hardclock_ticks now: %d\n", hardclock_ticks); 438 #ifdef _LP64 439 db_printf(" ticks wheel arg func\n"); 440 #else 441 db_printf(" ticks wheel arg func\n"); 442 #endif 443 444 /* 445 * Don't lock the callwheel; all the other CPUs are paused 446 * anyhow, and we might be called in a circumstance where 447 * some other CPU was paused while holding the lock. 448 */ 449 450 db_show_callout_bucket(&timeout_todo); 451 for (b = 0; b < BUCKETS; b++) 452 db_show_callout_bucket(&timeout_wheel[b]); 453 } 454 #endif /* DDB */ 455
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