1 /* 2 * Copyright (c) 2004 The DragonFly Project. All rights reserved. 3 * 4 * This code is derived from software contributed to The DragonFly Project 5 * by Matthew Dillon <dillon@backplane.com> 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 11 * 1. Redistributions of source code must retain the above copyright 12 * notice, this list of conditions and the following disclaimer. 13 * 2. Redistributions in binary form must reproduce the above copyright 14 * notice, this list of conditions and the following disclaimer in 15 * the documentation and/or other materials provided with the 16 * distribution. 17 * 3. Neither the name of The DragonFly Project nor the names of its 18 * contributors may be used to endorse or promote products derived 19 * from this software without specific, prior written permission. 20 * 21 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 22 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 23 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS 24 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE 25 * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, 26 * INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING, 27 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; 28 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED 29 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, 30 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT 31 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 32 * SUCH DAMAGE. 33 */ 34 /* 35 * Copyright (c) 1982, 1986, 1991, 1993 36 * The Regents of the University of California. All rights reserved. 37 * (c) UNIX System Laboratories, Inc. 38 * All or some portions of this file are derived from material licensed 39 * to the University of California by American Telephone and Telegraph 40 * Co. or Unix System Laboratories, Inc. and are reproduced herein with 41 * the permission of UNIX System Laboratories, Inc. 42 * 43 * Redistribution and use in source and binary forms, with or without 44 * modification, are permitted provided that the following conditions 45 * are met: 46 * 1. Redistributions of source code must retain the above copyright 47 * notice, this list of conditions and the following disclaimer. 48 * 2. Redistributions in binary form must reproduce the above copyright 49 * notice, this list of conditions and the following disclaimer in the 50 * documentation and/or other materials provided with the distribution. 51 * 3. All advertising materials mentioning features or use of this software 52 * must display the following acknowledgement: 53 * This product includes software developed by the University of 54 * California, Berkeley and its contributors. 55 * 4. Neither the name of the University nor the names of its contributors 56 * may be used to endorse or promote products derived from this software 57 * without specific prior written permission. 58 * 59 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 60 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 61 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 62 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 63 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 64 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 65 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 66 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 67 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 68 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 69 * SUCH DAMAGE. 70 * 71 * From: @(#)kern_clock.c 8.5 (Berkeley) 1/21/94 72 * $FreeBSD: src/sys/kern/kern_timeout.c,v 1.59.2.1 2001/11/13 18:24:52 archie Exp $ 73 * $DragonFly: src/sys/kern/kern_timeout.c,v 1.25 2007/04/30 07:18:54 dillon Exp $ 74 */ 75 /* 76 * DRAGONFLY BGL STATUS 77 * 78 * All the API functions should be MP safe. 79 * 80 * The callback functions will be flagged as being MP safe if the 81 * timeout structure is initialized with callout_init_mp() instead of 82 * callout_init(). 83 * 84 * The helper threads cannot be made preempt-capable until after we 85 * clean up all the uses of splsoftclock() and related interlocks (which 86 * require the related functions to be MP safe as well). 87 */ 88 /* 89 * The callout mechanism is based on the work of Adam M. Costello and 90 * George Varghese, published in a technical report entitled "Redesigning 91 * the BSD Callout and Timer Facilities" and modified slightly for inclusion 92 * in FreeBSD by Justin T. Gibbs. The original work on the data structures 93 * used in this implementation was published by G. Varghese and T. Lauck in 94 * the paper "Hashed and Hierarchical Timing Wheels: Data Structures for 95 * the Efficient Implementation of a Timer Facility" in the Proceedings of 96 * the 11th ACM Annual Symposium on Operating Systems Principles, 97 * Austin, Texas Nov 1987. 98 * 99 * The per-cpu augmentation was done by Matthew Dillon. 100 */ 101 102 #include "opt_ddb.h" 103 104 #include <sys/param.h> 105 #include <sys/systm.h> 106 #include <sys/callout.h> 107 #include <sys/kernel.h> 108 #include <sys/interrupt.h> 109 #include <sys/thread.h> 110 #include <sys/thread2.h> 111 #include <ddb/ddb.h> 112 113 #ifndef MAX_SOFTCLOCK_STEPS 114 #define MAX_SOFTCLOCK_STEPS 100 /* Maximum allowed value of steps. */ 115 #endif 116 117 118 struct softclock_pcpu { 119 struct callout_tailq *callwheel; 120 struct callout * volatile next; 121 int softticks; /* softticks index */ 122 int curticks; /* per-cpu ticks counter */ 123 int isrunning; 124 struct thread thread; 125 126 }; 127 128 typedef struct softclock_pcpu *softclock_pcpu_t; 129 130 /* 131 * TODO: 132 * allocate more timeout table slots when table overflows. 133 */ 134 static MALLOC_DEFINE(M_CALLOUT, "callout", "callout structures"); 135 static int callwheelsize; 136 static int callwheelbits; 137 static int callwheelmask; 138 static struct softclock_pcpu softclock_pcpu_ary[MAXCPU]; 139 140 static void softclock_handler(void *arg); 141 142 static void 143 swi_softclock_setup(void *arg) 144 { 145 int cpu; 146 int i; 147 148 /* 149 * Figure out how large a callwheel we need. It must be a power of 2. 150 */ 151 callwheelsize = 1; 152 callwheelbits = 0; 153 while (callwheelsize < ncallout) { 154 callwheelsize <<= 1; 155 ++callwheelbits; 156 } 157 callwheelmask = callwheelsize - 1; 158 159 /* 160 * Initialize per-cpu data structures. 161 */ 162 for (cpu = 0; cpu < ncpus; ++cpu) { 163 softclock_pcpu_t sc; 164 165 sc = &softclock_pcpu_ary[cpu]; 166 167 sc->callwheel = kmalloc(sizeof(*sc->callwheel) * callwheelsize, 168 M_CALLOUT, M_WAITOK|M_ZERO); 169 for (i = 0; i < callwheelsize; ++i) 170 TAILQ_INIT(&sc->callwheel[i]); 171 172 /* 173 * Create a preemption-capable thread for each cpu to handle 174 * softclock timeouts on that cpu. The preemption can only 175 * be blocked by a critical section. The thread can itself 176 * be preempted by normal interrupts. 177 */ 178 lwkt_create(softclock_handler, sc, NULL, 179 &sc->thread, TDF_STOPREQ|TDF_INTTHREAD, cpu, 180 "softclock %d", cpu); 181 #if 0 182 /* 183 * Do not make the thread preemptable until we clean up all 184 * the splsoftclock() calls in the system. Since the threads 185 * are no longer operated as a software interrupt, the 186 * splsoftclock() calls will not have any effect on them. 187 */ 188 sc->thread.td_preemptable = lwkt_preempt; 189 #endif 190 } 191 } 192 193 /* 194 * Must occur after ncpus has been initialized. 195 */ 196 SYSINIT(softclock_setup, SI_BOOT2_SOFTCLOCK, SI_ORDER_SECOND, 197 swi_softclock_setup, NULL); 198 199 /* 200 * This routine is called from the hardclock() (basically a FASTint/IPI) on 201 * each cpu in the system. sc->curticks is this cpu's notion of the timebase. 202 * It IS NOT NECESSARILY SYNCHRONIZED WITH 'ticks'! sc->softticks is where 203 * the callwheel is currently indexed. 204 * 205 * WARNING! The MP lock is not necessarily held on call, nor can it be 206 * safely obtained. 207 * 208 * sc->softticks is adjusted by either this routine or our helper thread 209 * depending on whether the helper thread is running or not. 210 */ 211 void 212 hardclock_softtick(globaldata_t gd) 213 { 214 softclock_pcpu_t sc; 215 216 sc = &softclock_pcpu_ary[gd->gd_cpuid]; 217 ++sc->curticks; 218 if (sc->isrunning) 219 return; 220 if (sc->softticks == sc->curticks) { 221 /* 222 * in sync, only wakeup the thread if there is something to 223 * do. 224 */ 225 if (TAILQ_FIRST(&sc->callwheel[sc->softticks & callwheelmask])) 226 { 227 sc->isrunning = 1; 228 lwkt_schedule(&sc->thread); 229 } else { 230 ++sc->softticks; 231 } 232 } else { 233 /* 234 * out of sync, wakeup the thread unconditionally so it can 235 * catch up. 236 */ 237 sc->isrunning = 1; 238 lwkt_schedule(&sc->thread); 239 } 240 } 241 242 /* 243 * This procedure is the main loop of our per-cpu helper thread. The 244 * sc->isrunning flag prevents us from racing hardclock_softtick() and 245 * a critical section is sufficient to interlock sc->curticks and protect 246 * us from remote IPI's / list removal. 247 * 248 * The thread starts with the MP lock held and not in a critical section. 249 * The loop itself is MP safe while individual callbacks may or may not 250 * be, so we obtain or release the MP lock as appropriate. 251 */ 252 static void 253 softclock_handler(void *arg) 254 { 255 softclock_pcpu_t sc; 256 struct callout *c; 257 struct callout_tailq *bucket; 258 void (*c_func)(void *); 259 void *c_arg; 260 #ifdef SMP 261 int mpsafe = 0; 262 #endif 263 264 lwkt_setpri_self(TDPRI_SOFT_NORM); 265 266 sc = arg; 267 crit_enter(); 268 loop: 269 while (sc->softticks != (int)(sc->curticks + 1)) { 270 bucket = &sc->callwheel[sc->softticks & callwheelmask]; 271 272 for (c = TAILQ_FIRST(bucket); c; c = sc->next) { 273 if (c->c_time != sc->softticks) { 274 sc->next = TAILQ_NEXT(c, c_links.tqe); 275 continue; 276 } 277 #ifdef SMP 278 if (c->c_flags & CALLOUT_MPSAFE) { 279 if (mpsafe == 0) { 280 mpsafe = 1; 281 rel_mplock(); 282 } 283 } else { 284 /* 285 * The request might be removed while we 286 * are waiting to get the MP lock. If it 287 * was removed sc->next will point to the 288 * next valid request or NULL, loop up. 289 */ 290 if (mpsafe) { 291 mpsafe = 0; 292 sc->next = c; 293 get_mplock(); 294 if (c != sc->next) 295 continue; 296 } 297 } 298 #endif 299 sc->next = TAILQ_NEXT(c, c_links.tqe); 300 TAILQ_REMOVE(bucket, c, c_links.tqe); 301 302 c_func = c->c_func; 303 c_arg = c->c_arg; 304 c->c_func = NULL; 305 KKASSERT(c->c_flags & CALLOUT_DID_INIT); 306 c->c_flags &= ~CALLOUT_PENDING; 307 crit_exit(); 308 c_func(c_arg); 309 crit_enter(); 310 /* NOTE: list may have changed */ 311 } 312 ++sc->softticks; 313 } 314 sc->isrunning = 0; 315 lwkt_deschedule_self(&sc->thread); /* == curthread */ 316 lwkt_switch(); 317 goto loop; 318 /* NOT REACHED */ 319 } 320 321 #if 0 322 323 /* 324 * timeout -- 325 * Execute a function after a specified length of time. 326 * 327 * untimeout -- 328 * Cancel previous timeout function call. 329 * 330 * callout_handle_init -- 331 * Initialize a handle so that using it with untimeout is benign. 332 * 333 * See AT&T BCI Driver Reference Manual for specification. This 334 * implementation differs from that one in that although an 335 * identification value is returned from timeout, the original 336 * arguments to timeout as well as the identifier are used to 337 * identify entries for untimeout. 338 */ 339 struct callout_handle 340 timeout(timeout_t *ftn, void *arg, int to_ticks) 341 { 342 softclock_pcpu_t sc; 343 struct callout *new; 344 struct callout_handle handle; 345 346 sc = &softclock_pcpu_ary[mycpu->gd_cpuid]; 347 crit_enter(); 348 349 /* Fill in the next free callout structure. */ 350 new = SLIST_FIRST(&sc->callfree); 351 if (new == NULL) { 352 /* XXX Attempt to malloc first */ 353 panic("timeout table full"); 354 } 355 SLIST_REMOVE_HEAD(&sc->callfree, c_links.sle); 356 357 callout_reset(new, to_ticks, ftn, arg); 358 359 handle.callout = new; 360 crit_exit(); 361 return (handle); 362 } 363 364 void 365 untimeout(timeout_t *ftn, void *arg, struct callout_handle handle) 366 { 367 /* 368 * Check for a handle that was initialized 369 * by callout_handle_init, but never used 370 * for a real timeout. 371 */ 372 if (handle.callout == NULL) 373 return; 374 375 crit_enter(); 376 if (handle.callout->c_func == ftn && handle.callout->c_arg == arg) 377 callout_stop(handle.callout); 378 crit_exit(); 379 } 380 381 void 382 callout_handle_init(struct callout_handle *handle) 383 { 384 handle->callout = NULL; 385 } 386 387 #endif 388 389 /* 390 * New interface; clients allocate their own callout structures. 391 * 392 * callout_reset() - establish or change a timeout 393 * callout_stop() - disestablish a timeout 394 * callout_init() - initialize a callout structure so that it can 395 * safely be passed to callout_reset() and callout_stop() 396 * callout_init_mp() - same but any installed functions must be MP safe. 397 * 398 * <sys/callout.h> defines three convenience macros: 399 * 400 * callout_active() - returns truth if callout has not been serviced 401 * callout_pending() - returns truth if callout is still waiting for timeout 402 * callout_deactivate() - marks the callout as having been serviced 403 */ 404 405 /* 406 * Start or restart a timeout. Install the callout structure in the 407 * callwheel. Callers may legally pass any value, even if 0 or negative, 408 * but since the sc->curticks index may have already been processed a 409 * minimum timeout of 1 tick will be enforced. 410 * 411 * The callout is installed on and will be processed on the current cpu's 412 * callout wheel. 413 */ 414 void 415 callout_reset(struct callout *c, int to_ticks, void (*ftn)(void *), 416 void *arg) 417 { 418 softclock_pcpu_t sc; 419 globaldata_t gd; 420 421 #ifdef INVARIANTS 422 if ((c->c_flags & CALLOUT_DID_INIT) == 0) { 423 callout_init(c); 424 kprintf( 425 "callout_reset(%p) from %p: callout was not initialized\n", 426 c, ((int **)&c)[-1]); 427 #ifdef DDB 428 db_print_backtrace(); 429 #endif 430 } 431 #endif 432 gd = mycpu; 433 sc = &softclock_pcpu_ary[gd->gd_cpuid]; 434 crit_enter_gd(gd); 435 436 if (c->c_flags & CALLOUT_PENDING) 437 callout_stop(c); 438 439 if (to_ticks <= 0) 440 to_ticks = 1; 441 442 c->c_arg = arg; 443 c->c_flags |= (CALLOUT_ACTIVE | CALLOUT_PENDING); 444 c->c_func = ftn; 445 c->c_time = sc->curticks + to_ticks; 446 #ifdef SMP 447 c->c_gd = gd; 448 #endif 449 450 TAILQ_INSERT_TAIL(&sc->callwheel[c->c_time & callwheelmask], 451 c, c_links.tqe); 452 crit_exit_gd(gd); 453 } 454 455 /* 456 * Stop a running timer. WARNING! If called on a cpu other then the one 457 * the callout was started on this function will liveloop on its IPI to 458 * the target cpu to process the request. It is possible for the callout 459 * to execute in that case. 460 * 461 * WARNING! This routine may be called from an IPI 462 */ 463 int 464 callout_stop(struct callout *c) 465 { 466 globaldata_t gd = mycpu; 467 #ifdef SMP 468 globaldata_t tgd; 469 #endif 470 softclock_pcpu_t sc; 471 472 #ifdef INVARIANTS 473 if ((c->c_flags & CALLOUT_DID_INIT) == 0) { 474 callout_init(c); 475 kprintf( 476 "callout_stop(%p) from %p: callout was not initialized\n", 477 c, ((int **)&c)[-1]); 478 #ifdef DDB 479 db_print_backtrace(); 480 #endif 481 } 482 #endif 483 crit_enter_gd(gd); 484 485 /* 486 * Don't attempt to delete a callout that's not on the queue. 487 */ 488 if ((c->c_flags & CALLOUT_PENDING) == 0) { 489 c->c_flags &= ~CALLOUT_ACTIVE; 490 crit_exit_gd(gd); 491 return (0); 492 } 493 #ifdef SMP 494 if ((tgd = c->c_gd) != gd) { 495 /* 496 * If the callout is owned by a different CPU we have to 497 * execute the function synchronously on the target cpu. 498 */ 499 int seq; 500 501 cpu_ccfence(); /* don't let tgd alias c_gd */ 502 seq = lwkt_send_ipiq(tgd, (void *)callout_stop, c); 503 lwkt_wait_ipiq(tgd, seq); 504 } else 505 #endif 506 { 507 /* 508 * If the callout is owned by the same CPU we can 509 * process it directly, but if we are racing our helper 510 * thread (sc->next), we have to adjust sc->next. The 511 * race is interlocked by a critical section. 512 */ 513 sc = &softclock_pcpu_ary[gd->gd_cpuid]; 514 515 c->c_flags &= ~(CALLOUT_ACTIVE | CALLOUT_PENDING); 516 if (sc->next == c) 517 sc->next = TAILQ_NEXT(c, c_links.tqe); 518 519 TAILQ_REMOVE(&sc->callwheel[c->c_time & callwheelmask], 520 c, c_links.tqe); 521 c->c_func = NULL; 522 } 523 crit_exit_gd(gd); 524 return (1); 525 } 526 527 /* 528 * Prepare a callout structure for use by callout_reset() and/or 529 * callout_stop(). The MP version of this routine requires that the callback 530 * function installed by callout_reset() be MP safe. 531 */ 532 void 533 callout_init(struct callout *c) 534 { 535 bzero(c, sizeof *c); 536 c->c_flags = CALLOUT_DID_INIT; 537 } 538 539 void 540 callout_init_mp(struct callout *c) 541 { 542 callout_init(c); 543 c->c_flags |= CALLOUT_MPSAFE; 544 } 545 546 /* What, are you joking? This is nuts! -Matt */ 547 #if 0 548 #ifdef APM_FIXUP_CALLTODO 549 /* 550 * Adjust the kernel calltodo timeout list. This routine is used after 551 * an APM resume to recalculate the calltodo timer list values with the 552 * number of hz's we have been sleeping. The next hardclock() will detect 553 * that there are fired timers and run softclock() to execute them. 554 * 555 * Please note, I have not done an exhaustive analysis of what code this 556 * might break. I am motivated to have my select()'s and alarm()'s that 557 * have expired during suspend firing upon resume so that the applications 558 * which set the timer can do the maintanence the timer was for as close 559 * as possible to the originally intended time. Testing this code for a 560 * week showed that resuming from a suspend resulted in 22 to 25 timers 561 * firing, which seemed independant on whether the suspend was 2 hours or 562 * 2 days. Your milage may vary. - Ken Key <key@cs.utk.edu> 563 */ 564 void 565 adjust_timeout_calltodo(struct timeval *time_change) 566 { 567 struct callout *p; 568 unsigned long delta_ticks; 569 570 /* 571 * How many ticks were we asleep? 572 * (stolen from tvtohz()). 573 */ 574 575 /* Don't do anything */ 576 if (time_change->tv_sec < 0) 577 return; 578 else if (time_change->tv_sec <= LONG_MAX / 1000000) 579 delta_ticks = (time_change->tv_sec * 1000000 + 580 time_change->tv_usec + (tick - 1)) / tick + 1; 581 else if (time_change->tv_sec <= LONG_MAX / hz) 582 delta_ticks = time_change->tv_sec * hz + 583 (time_change->tv_usec + (tick - 1)) / tick + 1; 584 else 585 delta_ticks = LONG_MAX; 586 587 if (delta_ticks > INT_MAX) 588 delta_ticks = INT_MAX; 589 590 /* 591 * Now rip through the timer calltodo list looking for timers 592 * to expire. 593 */ 594 595 /* don't collide with softclock() */ 596 crit_enter(); 597 for (p = calltodo.c_next; p != NULL; p = p->c_next) { 598 p->c_time -= delta_ticks; 599 600 /* Break if the timer had more time on it than delta_ticks */ 601 if (p->c_time > 0) 602 break; 603 604 /* take back the ticks the timer didn't use (p->c_time <= 0) */ 605 delta_ticks = -p->c_time; 606 } 607 crit_exit(); 608 609 return; 610 } 611 #endif /* APM_FIXUP_CALLTODO */ 612 #endif 613 614