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 */ 40 41 #include <sys/cdefs.h> 42 __FBSDID("$FreeBSD$"); 43 44 #include <sys/param.h> 45 #include <sys/systm.h> 46 #include <sys/callout.h> 47 #include <sys/kernel.h> 48 #include <sys/lock.h> 49 #include <sys/mutex.h> 50 #include <sys/sysctl.h> 51 52 static int avg_depth; 53 SYSCTL_INT(_debug, OID_AUTO, to_avg_depth, CTLFLAG_RD, &avg_depth, 0, 54 "Average number of items examined per softclock call. Units = 1/1000"); 55 static int avg_gcalls; 56 SYSCTL_INT(_debug, OID_AUTO, to_avg_gcalls, CTLFLAG_RD, &avg_gcalls, 0, 57 "Average number of Giant callouts made per softclock call. Units = 1/1000"); 58 static int avg_mpcalls; 59 SYSCTL_INT(_debug, OID_AUTO, to_avg_mpcalls, CTLFLAG_RD, &avg_mpcalls, 0, 60 "Average number of MP callouts made per softclock call. Units = 1/1000"); 61 /* 62 * TODO: 63 * allocate more timeout table slots when table overflows. 64 */ 65 66 /* Exported to machdep.c and/or kern_clock.c. */ 67 struct callout *callout; 68 struct callout_list callfree; 69 int callwheelsize, callwheelbits, callwheelmask; 70 struct callout_tailq *callwheel; 71 int softticks; /* Like ticks, but for softclock(). */ 72 struct mtx callout_lock; 73 74 static struct callout *nextsoftcheck; /* Next callout to be checked. */ 75 76 /* 77 * kern_timeout_callwheel_alloc() - kernel low level callwheel initialization 78 * 79 * This code is called very early in the kernel initialization sequence, 80 * and may be called more then once. 81 */ 82 caddr_t 83 kern_timeout_callwheel_alloc(caddr_t v) 84 { 85 /* 86 * Calculate callout wheel size 87 */ 88 for (callwheelsize = 1, callwheelbits = 0; 89 callwheelsize < ncallout; 90 callwheelsize <<= 1, ++callwheelbits) 91 ; 92 callwheelmask = callwheelsize - 1; 93 94 callout = (struct callout *)v; 95 v = (caddr_t)(callout + ncallout); 96 callwheel = (struct callout_tailq *)v; 97 v = (caddr_t)(callwheel + callwheelsize); 98 return(v); 99 } 100 101 /* 102 * kern_timeout_callwheel_init() - initialize previously reserved callwheel 103 * space. 104 * 105 * This code is called just once, after the space reserved for the 106 * callout wheel has been finalized. 107 */ 108 void 109 kern_timeout_callwheel_init(void) 110 { 111 int i; 112 113 SLIST_INIT(&callfree); 114 for (i = 0; i < ncallout; i++) { 115 callout_init(&callout[i], 0); 116 callout[i].c_flags = CALLOUT_LOCAL_ALLOC; 117 SLIST_INSERT_HEAD(&callfree, &callout[i], c_links.sle); 118 } 119 for (i = 0; i < callwheelsize; i++) { 120 TAILQ_INIT(&callwheel[i]); 121 } 122 mtx_init(&callout_lock, "callout", NULL, MTX_SPIN | MTX_RECURSE); 123 } 124 125 /* 126 * The callout mechanism is based on the work of Adam M. Costello and 127 * George Varghese, published in a technical report entitled "Redesigning 128 * the BSD Callout and Timer Facilities" and modified slightly for inclusion 129 * in FreeBSD by Justin T. Gibbs. The original work on the data structures 130 * used in this implementation was published by G.Varghese and A. Lauck in 131 * the paper "Hashed and Hierarchical Timing Wheels: Data Structures for 132 * the Efficient Implementation of a Timer Facility" in the Proceedings of 133 * the 11th ACM Annual Symposium on Operating Systems Principles, 134 * Austin, Texas Nov 1987. 135 */ 136 137 /* 138 * Software (low priority) clock interrupt. 139 * Run periodic events from timeout queue. 140 */ 141 void 142 softclock(void *dummy) 143 { 144 struct callout *c; 145 struct callout_tailq *bucket; 146 int curticks; 147 int steps; /* #steps since we last allowed interrupts */ 148 int depth; 149 int mpcalls; 150 int gcalls; 151 152 #ifndef MAX_SOFTCLOCK_STEPS 153 #define MAX_SOFTCLOCK_STEPS 100 /* Maximum allowed value of steps. */ 154 #endif /* MAX_SOFTCLOCK_STEPS */ 155 156 mpcalls = 0; 157 gcalls = 0; 158 depth = 0; 159 steps = 0; 160 mtx_lock_spin(&callout_lock); 161 while (softticks != ticks) { 162 softticks++; 163 /* 164 * softticks may be modified by hard clock, so cache 165 * it while we work on a given bucket. 166 */ 167 curticks = softticks; 168 bucket = &callwheel[curticks & callwheelmask]; 169 c = TAILQ_FIRST(bucket); 170 while (c) { 171 depth++; 172 if (c->c_time != curticks) { 173 c = TAILQ_NEXT(c, c_links.tqe); 174 ++steps; 175 if (steps >= MAX_SOFTCLOCK_STEPS) { 176 nextsoftcheck = c; 177 /* Give interrupts a chance. */ 178 mtx_unlock_spin(&callout_lock); 179 ; /* nothing */ 180 mtx_lock_spin(&callout_lock); 181 c = nextsoftcheck; 182 steps = 0; 183 } 184 } else { 185 void (*c_func)(void *); 186 void *c_arg; 187 int c_flags; 188 189 nextsoftcheck = TAILQ_NEXT(c, c_links.tqe); 190 TAILQ_REMOVE(bucket, c, c_links.tqe); 191 c_func = c->c_func; 192 c_arg = c->c_arg; 193 c_flags = c->c_flags; 194 c->c_func = NULL; 195 if (c->c_flags & CALLOUT_LOCAL_ALLOC) { 196 c->c_flags = CALLOUT_LOCAL_ALLOC; 197 SLIST_INSERT_HEAD(&callfree, c, 198 c_links.sle); 199 } else { 200 c->c_flags = 201 (c->c_flags & ~CALLOUT_PENDING); 202 } 203 mtx_unlock_spin(&callout_lock); 204 if (!(c_flags & CALLOUT_MPSAFE)) { 205 mtx_lock(&Giant); 206 gcalls++; 207 } else { 208 mpcalls++; 209 } 210 c_func(c_arg); 211 if (!(c_flags & CALLOUT_MPSAFE)) 212 mtx_unlock(&Giant); 213 mtx_lock_spin(&callout_lock); 214 steps = 0; 215 c = nextsoftcheck; 216 } 217 } 218 } 219 avg_depth += (depth * 1000 - avg_depth) >> 8; 220 avg_mpcalls += (mpcalls * 1000 - avg_mpcalls) >> 8; 221 avg_gcalls += (gcalls * 1000 - avg_gcalls) >> 8; 222 nextsoftcheck = NULL; 223 mtx_unlock_spin(&callout_lock); 224 } 225 226 /* 227 * timeout -- 228 * Execute a function after a specified length of time. 229 * 230 * untimeout -- 231 * Cancel previous timeout function call. 232 * 233 * callout_handle_init -- 234 * Initialize a handle so that using it with untimeout is benign. 235 * 236 * See AT&T BCI Driver Reference Manual for specification. This 237 * implementation differs from that one in that although an 238 * identification value is returned from timeout, the original 239 * arguments to timeout as well as the identifier are used to 240 * identify entries for untimeout. 241 */ 242 struct callout_handle 243 timeout(ftn, arg, to_ticks) 244 timeout_t *ftn; 245 void *arg; 246 int to_ticks; 247 { 248 struct callout *new; 249 struct callout_handle handle; 250 251 mtx_lock_spin(&callout_lock); 252 253 /* Fill in the next free callout structure. */ 254 new = SLIST_FIRST(&callfree); 255 if (new == NULL) 256 /* XXX Attempt to malloc first */ 257 panic("timeout table full"); 258 SLIST_REMOVE_HEAD(&callfree, c_links.sle); 259 260 callout_reset(new, to_ticks, ftn, arg); 261 262 handle.callout = new; 263 mtx_unlock_spin(&callout_lock); 264 return (handle); 265 } 266 267 void 268 untimeout(ftn, arg, handle) 269 timeout_t *ftn; 270 void *arg; 271 struct callout_handle handle; 272 { 273 274 /* 275 * Check for a handle that was initialized 276 * by callout_handle_init, but never used 277 * for a real timeout. 278 */ 279 if (handle.callout == NULL) 280 return; 281 282 mtx_lock_spin(&callout_lock); 283 if (handle.callout->c_func == ftn && handle.callout->c_arg == arg) 284 callout_stop(handle.callout); 285 mtx_unlock_spin(&callout_lock); 286 } 287 288 void 289 callout_handle_init(struct callout_handle *handle) 290 { 291 handle->callout = NULL; 292 } 293 294 /* 295 * New interface; clients allocate their own callout structures. 296 * 297 * callout_reset() - establish or change a timeout 298 * callout_stop() - disestablish a timeout 299 * callout_init() - initialize a callout structure so that it can 300 * safely be passed to callout_reset() and callout_stop() 301 * 302 * <sys/callout.h> defines three convenience macros: 303 * 304 * callout_active() - returns truth if callout has not been serviced 305 * callout_pending() - returns truth if callout is still waiting for timeout 306 * callout_deactivate() - marks the callout as having been serviced 307 */ 308 void 309 callout_reset(c, to_ticks, ftn, arg) 310 struct callout *c; 311 int to_ticks; 312 void (*ftn)(void *); 313 void *arg; 314 { 315 316 mtx_lock_spin(&callout_lock); 317 if (c->c_flags & CALLOUT_PENDING) 318 callout_stop(c); 319 320 /* 321 * We could unlock callout_lock here and lock it again before the 322 * TAILQ_INSERT_TAIL, but there's no point since doing this setup 323 * doesn't take much time. 324 */ 325 if (to_ticks <= 0) 326 to_ticks = 1; 327 328 c->c_arg = arg; 329 c->c_flags |= (CALLOUT_ACTIVE | CALLOUT_PENDING); 330 c->c_func = ftn; 331 c->c_time = ticks + to_ticks; 332 TAILQ_INSERT_TAIL(&callwheel[c->c_time & callwheelmask], 333 c, c_links.tqe); 334 mtx_unlock_spin(&callout_lock); 335 } 336 337 int 338 callout_stop(c) 339 struct callout *c; 340 { 341 342 mtx_lock_spin(&callout_lock); 343 /* 344 * Don't attempt to delete a callout that's not on the queue. 345 */ 346 if (!(c->c_flags & CALLOUT_PENDING)) { 347 c->c_flags &= ~CALLOUT_ACTIVE; 348 mtx_unlock_spin(&callout_lock); 349 return (0); 350 } 351 c->c_flags &= ~(CALLOUT_ACTIVE | CALLOUT_PENDING); 352 353 if (nextsoftcheck == c) { 354 nextsoftcheck = TAILQ_NEXT(c, c_links.tqe); 355 } 356 TAILQ_REMOVE(&callwheel[c->c_time & callwheelmask], c, c_links.tqe); 357 c->c_func = NULL; 358 359 if (c->c_flags & CALLOUT_LOCAL_ALLOC) { 360 SLIST_INSERT_HEAD(&callfree, c, c_links.sle); 361 } 362 mtx_unlock_spin(&callout_lock); 363 return (1); 364 } 365 366 void 367 callout_init(c, mpsafe) 368 struct callout *c; 369 int mpsafe; 370 { 371 bzero(c, sizeof *c); 372 if (mpsafe) 373 c->c_flags |= CALLOUT_MPSAFE; 374 } 375 376 #ifdef APM_FIXUP_CALLTODO 377 /* 378 * Adjust the kernel calltodo timeout list. This routine is used after 379 * an APM resume to recalculate the calltodo timer list values with the 380 * number of hz's we have been sleeping. The next hardclock() will detect 381 * that there are fired timers and run softclock() to execute them. 382 * 383 * Please note, I have not done an exhaustive analysis of what code this 384 * might break. I am motivated to have my select()'s and alarm()'s that 385 * have expired during suspend firing upon resume so that the applications 386 * which set the timer can do the maintanence the timer was for as close 387 * as possible to the originally intended time. Testing this code for a 388 * week showed that resuming from a suspend resulted in 22 to 25 timers 389 * firing, which seemed independant on whether the suspend was 2 hours or 390 * 2 days. Your milage may vary. - Ken Key <key@cs.utk.edu> 391 */ 392 void 393 adjust_timeout_calltodo(time_change) 394 struct timeval *time_change; 395 { 396 register struct callout *p; 397 unsigned long delta_ticks; 398 399 /* 400 * How many ticks were we asleep? 401 * (stolen from tvtohz()). 402 */ 403 404 /* Don't do anything */ 405 if (time_change->tv_sec < 0) 406 return; 407 else if (time_change->tv_sec <= LONG_MAX / 1000000) 408 delta_ticks = (time_change->tv_sec * 1000000 + 409 time_change->tv_usec + (tick - 1)) / tick + 1; 410 else if (time_change->tv_sec <= LONG_MAX / hz) 411 delta_ticks = time_change->tv_sec * hz + 412 (time_change->tv_usec + (tick - 1)) / tick + 1; 413 else 414 delta_ticks = LONG_MAX; 415 416 if (delta_ticks > INT_MAX) 417 delta_ticks = INT_MAX; 418 419 /* 420 * Now rip through the timer calltodo list looking for timers 421 * to expire. 422 */ 423 424 /* don't collide with softclock() */ 425 mtx_lock_spin(&callout_lock); 426 for (p = calltodo.c_next; p != NULL; p = p->c_next) { 427 p->c_time -= delta_ticks; 428 429 /* Break if the timer had more time on it than delta_ticks */ 430 if (p->c_time > 0) 431 break; 432 433 /* take back the ticks the timer didn't use (p->c_time <= 0) */ 434 delta_ticks = -p->c_time; 435 } 436 mtx_unlock_spin(&callout_lock); 437 438 return; 439 } 440 #endif /* APM_FIXUP_CALLTODO */ 441