1 /*- 2 * Copyright (c) 1982, 1986, 1990, 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 * 4. Neither the name of the University nor the names of its contributors 19 * may be used to endorse or promote products derived from this software 20 * without specific prior written permission. 21 * 22 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 25 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 32 * SUCH DAMAGE. 33 * 34 * @(#)kern_synch.c 8.9 (Berkeley) 5/19/95 35 */ 36 37 #include <sys/cdefs.h> 38 __FBSDID("$FreeBSD$"); 39 40 #include "opt_ktrace.h" 41 42 #include <sys/param.h> 43 #include <sys/systm.h> 44 #include <sys/condvar.h> 45 #include <sys/kdb.h> 46 #include <sys/kernel.h> 47 #include <sys/ktr.h> 48 #include <sys/lock.h> 49 #include <sys/mutex.h> 50 #include <sys/proc.h> 51 #include <sys/resourcevar.h> 52 #include <sys/sched.h> 53 #include <sys/signalvar.h> 54 #include <sys/sleepqueue.h> 55 #include <sys/smp.h> 56 #include <sys/sx.h> 57 #include <sys/sysctl.h> 58 #include <sys/sysproto.h> 59 #include <sys/vmmeter.h> 60 #ifdef KTRACE 61 #include <sys/uio.h> 62 #include <sys/ktrace.h> 63 #endif 64 65 #include <machine/cpu.h> 66 67 static void synch_setup(void *dummy); 68 SYSINIT(synch_setup, SI_SUB_KICK_SCHEDULER, SI_ORDER_FIRST, synch_setup, NULL) 69 70 int hogticks; 71 int lbolt; 72 static int pause_wchan; 73 74 static struct callout loadav_callout; 75 static struct callout lbolt_callout; 76 77 struct loadavg averunnable = 78 { {0, 0, 0}, FSCALE }; /* load average, of runnable procs */ 79 /* 80 * Constants for averages over 1, 5, and 15 minutes 81 * when sampling at 5 second intervals. 82 */ 83 static fixpt_t cexp[3] = { 84 0.9200444146293232 * FSCALE, /* exp(-1/12) */ 85 0.9834714538216174 * FSCALE, /* exp(-1/60) */ 86 0.9944598480048967 * FSCALE, /* exp(-1/180) */ 87 }; 88 89 /* kernel uses `FSCALE', userland (SHOULD) use kern.fscale */ 90 static int fscale __unused = FSCALE; 91 SYSCTL_INT(_kern, OID_AUTO, fscale, CTLFLAG_RD, 0, FSCALE, ""); 92 93 static void loadav(void *arg); 94 static void lboltcb(void *arg); 95 96 void 97 sleepinit(void) 98 { 99 100 hogticks = (hz / 10) * 2; /* Default only. */ 101 init_sleepqueues(); 102 } 103 104 /* 105 * General sleep call. Suspends the current thread until a wakeup is 106 * performed on the specified identifier. The thread will then be made 107 * runnable with the specified priority. Sleeps at most timo/hz seconds 108 * (0 means no timeout). If pri includes PCATCH flag, signals are checked 109 * before and after sleeping, else signals are not checked. Returns 0 if 110 * awakened, EWOULDBLOCK if the timeout expires. If PCATCH is set and a 111 * signal needs to be delivered, ERESTART is returned if the current system 112 * call should be restarted if possible, and EINTR is returned if the system 113 * call should be interrupted by the signal (return EINTR). 114 * 115 * The lock argument is unlocked before the caller is suspended, and 116 * re-locked before _sleep() returns. If priority includes the PDROP 117 * flag the lock is not re-locked before returning. 118 */ 119 int 120 _sleep(ident, lock, priority, wmesg, timo) 121 void *ident; 122 struct lock_object *lock; 123 int priority, timo; 124 const char *wmesg; 125 { 126 struct thread *td; 127 struct proc *p; 128 struct lock_class *class; 129 int catch, flags, lock_state, pri, rval; 130 WITNESS_SAVE_DECL(lock_witness); 131 132 td = curthread; 133 p = td->td_proc; 134 #ifdef KTRACE 135 if (KTRPOINT(td, KTR_CSW)) 136 ktrcsw(1, 0); 137 #endif 138 WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, lock, 139 "Sleeping on \"%s\"", wmesg); 140 KASSERT(timo != 0 || mtx_owned(&Giant) || lock != NULL || 141 ident == &lbolt, ("sleeping without a lock")); 142 KASSERT(p != NULL, ("msleep1")); 143 KASSERT(ident != NULL && TD_IS_RUNNING(td), ("msleep")); 144 if (lock != NULL) 145 class = LOCK_CLASS(lock); 146 else 147 class = NULL; 148 149 if (cold) { 150 /* 151 * During autoconfiguration, just return; 152 * don't run any other threads or panic below, 153 * in case this is the idle thread and already asleep. 154 * XXX: this used to do "s = splhigh(); splx(safepri); 155 * splx(s);" to give interrupts a chance, but there is 156 * no way to give interrupts a chance now. 157 */ 158 if (lock != NULL && priority & PDROP) 159 class->lc_unlock(lock); 160 return (0); 161 } 162 catch = priority & PCATCH; 163 rval = 0; 164 165 /* 166 * If we are already on a sleep queue, then remove us from that 167 * sleep queue first. We have to do this to handle recursive 168 * sleeps. 169 */ 170 if (TD_ON_SLEEPQ(td)) 171 sleepq_remove(td, td->td_wchan); 172 173 if (ident == &pause_wchan) 174 flags = SLEEPQ_PAUSE; 175 else 176 flags = SLEEPQ_SLEEP; 177 if (catch) 178 flags |= SLEEPQ_INTERRUPTIBLE; 179 180 sleepq_lock(ident); 181 CTR5(KTR_PROC, "sleep: thread %ld (pid %ld, %s) on %s (%p)", 182 td->td_tid, p->p_pid, p->p_comm, wmesg, ident); 183 184 DROP_GIANT(); 185 if (lock != NULL && !(class->lc_flags & LC_SLEEPABLE)) { 186 WITNESS_SAVE(lock, lock_witness); 187 lock_state = class->lc_unlock(lock); 188 } else 189 /* GCC needs to follow the Yellow Brick Road */ 190 lock_state = -1; 191 192 /* 193 * We put ourselves on the sleep queue and start our timeout 194 * before calling thread_suspend_check, as we could stop there, 195 * and a wakeup or a SIGCONT (or both) could occur while we were 196 * stopped without resuming us. Thus, we must be ready for sleep 197 * when cursig() is called. If the wakeup happens while we're 198 * stopped, then td will no longer be on a sleep queue upon 199 * return from cursig(). 200 */ 201 sleepq_add(ident, ident == &lbolt ? NULL : lock, wmesg, flags, 0); 202 if (timo) 203 sleepq_set_timeout(ident, timo); 204 if (lock != NULL && class->lc_flags & LC_SLEEPABLE) { 205 sleepq_release(ident); 206 WITNESS_SAVE(lock, lock_witness); 207 lock_state = class->lc_unlock(lock); 208 sleepq_lock(ident); 209 } 210 211 /* 212 * Adjust this thread's priority, if necessary. 213 */ 214 pri = priority & PRIMASK; 215 if (pri != 0 && pri != td->td_priority) { 216 mtx_lock_spin(&sched_lock); 217 sched_prio(td, pri); 218 mtx_unlock_spin(&sched_lock); 219 } 220 221 if (timo && catch) 222 rval = sleepq_timedwait_sig(ident); 223 else if (timo) 224 rval = sleepq_timedwait(ident); 225 else if (catch) 226 rval = sleepq_wait_sig(ident); 227 else { 228 sleepq_wait(ident); 229 rval = 0; 230 } 231 #ifdef KTRACE 232 if (KTRPOINT(td, KTR_CSW)) 233 ktrcsw(0, 0); 234 #endif 235 PICKUP_GIANT(); 236 if (lock != NULL && !(priority & PDROP)) { 237 class->lc_lock(lock, lock_state); 238 WITNESS_RESTORE(lock, lock_witness); 239 } 240 return (rval); 241 } 242 243 int 244 msleep_spin(ident, mtx, wmesg, timo) 245 void *ident; 246 struct mtx *mtx; 247 const char *wmesg; 248 int timo; 249 { 250 struct thread *td; 251 struct proc *p; 252 int rval; 253 WITNESS_SAVE_DECL(mtx); 254 255 td = curthread; 256 p = td->td_proc; 257 KASSERT(mtx != NULL, ("sleeping without a mutex")); 258 KASSERT(p != NULL, ("msleep1")); 259 KASSERT(ident != NULL && TD_IS_RUNNING(td), ("msleep")); 260 261 if (cold) { 262 /* 263 * During autoconfiguration, just return; 264 * don't run any other threads or panic below, 265 * in case this is the idle thread and already asleep. 266 * XXX: this used to do "s = splhigh(); splx(safepri); 267 * splx(s);" to give interrupts a chance, but there is 268 * no way to give interrupts a chance now. 269 */ 270 return (0); 271 } 272 273 sleepq_lock(ident); 274 CTR5(KTR_PROC, "msleep_spin: thread %ld (pid %ld, %s) on %s (%p)", 275 td->td_tid, p->p_pid, p->p_comm, wmesg, ident); 276 277 DROP_GIANT(); 278 mtx_assert(mtx, MA_OWNED | MA_NOTRECURSED); 279 WITNESS_SAVE(&mtx->lock_object, mtx); 280 mtx_unlock_spin(mtx); 281 282 /* 283 * We put ourselves on the sleep queue and start our timeout. 284 */ 285 sleepq_add(ident, &mtx->lock_object, wmesg, SLEEPQ_SLEEP, 0); 286 if (timo) 287 sleepq_set_timeout(ident, timo); 288 289 /* 290 * Can't call ktrace with any spin locks held so it can lock the 291 * ktrace_mtx lock, and WITNESS_WARN considers it an error to hold 292 * any spin lock. Thus, we have to drop the sleepq spin lock while 293 * we handle those requests. This is safe since we have placed our 294 * thread on the sleep queue already. 295 */ 296 #ifdef KTRACE 297 if (KTRPOINT(td, KTR_CSW)) { 298 sleepq_release(ident); 299 ktrcsw(1, 0); 300 sleepq_lock(ident); 301 } 302 #endif 303 #ifdef WITNESS 304 sleepq_release(ident); 305 WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, NULL, "Sleeping on \"%s\"", 306 wmesg); 307 sleepq_lock(ident); 308 #endif 309 if (timo) 310 rval = sleepq_timedwait(ident); 311 else { 312 sleepq_wait(ident); 313 rval = 0; 314 } 315 #ifdef KTRACE 316 if (KTRPOINT(td, KTR_CSW)) 317 ktrcsw(0, 0); 318 #endif 319 PICKUP_GIANT(); 320 mtx_lock_spin(mtx); 321 WITNESS_RESTORE(&mtx->lock_object, mtx); 322 return (rval); 323 } 324 325 /* 326 * pause() is like tsleep() except that the intention is to not be 327 * explicitly woken up by another thread. Instead, the current thread 328 * simply wishes to sleep until the timeout expires. It is 329 * implemented using a dummy wait channel. 330 */ 331 int 332 pause(wmesg, timo) 333 const char *wmesg; 334 int timo; 335 { 336 337 KASSERT(timo != 0, ("pause: timeout required")); 338 return (tsleep(&pause_wchan, 0, wmesg, timo)); 339 } 340 341 /* 342 * Make all threads sleeping on the specified identifier runnable. 343 */ 344 void 345 wakeup(ident) 346 register void *ident; 347 { 348 349 sleepq_lock(ident); 350 sleepq_broadcast(ident, SLEEPQ_SLEEP, -1, 0); 351 } 352 353 /* 354 * Make a thread sleeping on the specified identifier runnable. 355 * May wake more than one thread if a target thread is currently 356 * swapped out. 357 */ 358 void 359 wakeup_one(ident) 360 register void *ident; 361 { 362 363 sleepq_lock(ident); 364 sleepq_signal(ident, SLEEPQ_SLEEP, -1, 0); 365 } 366 367 /* 368 * The machine independent parts of context switching. 369 */ 370 void 371 mi_switch(int flags, struct thread *newtd) 372 { 373 uint64_t new_switchtime; 374 struct thread *td; 375 struct proc *p; 376 377 mtx_assert(&sched_lock, MA_OWNED | MA_NOTRECURSED); 378 td = curthread; /* XXX */ 379 p = td->td_proc; /* XXX */ 380 KASSERT(!TD_ON_RUNQ(td), ("mi_switch: called by old code")); 381 #ifdef INVARIANTS 382 if (!TD_ON_LOCK(td) && !TD_IS_RUNNING(td)) 383 mtx_assert(&Giant, MA_NOTOWNED); 384 #endif 385 KASSERT(td->td_critnest == 1 || (td->td_critnest == 2 && 386 (td->td_owepreempt) && (flags & SW_INVOL) != 0 && 387 newtd == NULL) || panicstr, 388 ("mi_switch: switch in a critical section")); 389 KASSERT((flags & (SW_INVOL | SW_VOL)) != 0, 390 ("mi_switch: switch must be voluntary or involuntary")); 391 KASSERT(newtd != curthread, ("mi_switch: preempting back to ourself")); 392 393 /* 394 * Don't perform context switches from the debugger. 395 */ 396 if (kdb_active) { 397 mtx_unlock_spin(&sched_lock); 398 kdb_backtrace(); 399 kdb_reenter(); 400 panic("%s: did not reenter debugger", __func__); 401 } 402 403 if (flags & SW_VOL) 404 p->p_stats->p_ru.ru_nvcsw++; 405 else 406 p->p_stats->p_ru.ru_nivcsw++; 407 408 /* 409 * Compute the amount of time during which the current 410 * process was running, and add that to its total so far. 411 */ 412 new_switchtime = cpu_ticks(); 413 p->p_rux.rux_runtime += (new_switchtime - PCPU_GET(switchtime)); 414 p->p_rux.rux_uticks += td->td_uticks; 415 td->td_uticks = 0; 416 p->p_rux.rux_iticks += td->td_iticks; 417 td->td_iticks = 0; 418 p->p_rux.rux_sticks += td->td_sticks; 419 td->td_sticks = 0; 420 421 td->td_generation++; /* bump preempt-detect counter */ 422 423 /* 424 * Check if the process exceeds its cpu resource allocation. If 425 * it reaches the max, arrange to kill the process in ast(). 426 */ 427 if (p->p_cpulimit != RLIM_INFINITY && 428 p->p_rux.rux_runtime >= p->p_cpulimit * cpu_tickrate()) { 429 p->p_sflag |= PS_XCPU; 430 td->td_flags |= TDF_ASTPENDING; 431 } 432 433 /* 434 * Finish up stats for outgoing thread. 435 */ 436 VMCNT_ADD(swtch, 1); 437 PCPU_SET(switchtime, new_switchtime); 438 PCPU_SET(switchticks, ticks); 439 CTR4(KTR_PROC, "mi_switch: old thread %ld (kse %p, pid %ld, %s)", 440 td->td_tid, td->td_sched, p->p_pid, p->p_comm); 441 #if (KTR_COMPILE & KTR_SCHED) != 0 442 if (TD_IS_IDLETHREAD(td)) 443 CTR3(KTR_SCHED, "mi_switch: %p(%s) prio %d idle", 444 td, td->td_proc->p_comm, td->td_priority); 445 else if (newtd != NULL) 446 CTR5(KTR_SCHED, 447 "mi_switch: %p(%s) prio %d preempted by %p(%s)", 448 td, td->td_proc->p_comm, td->td_priority, newtd, 449 newtd->td_proc->p_comm); 450 else 451 CTR6(KTR_SCHED, 452 "mi_switch: %p(%s) prio %d inhibit %d wmesg %s lock %s", 453 td, td->td_proc->p_comm, td->td_priority, 454 td->td_inhibitors, td->td_wmesg, td->td_lockname); 455 #endif 456 /* 457 * We call thread_switchout after the KTR_SCHED prints above so kse 458 * selecting a new thread to run does not show up as a preemption. 459 */ 460 #ifdef KSE 461 if ((flags & SW_VOL) && (td->td_proc->p_flag & P_SA)) 462 newtd = thread_switchout(td, flags, newtd); 463 #endif 464 sched_switch(td, newtd, flags); 465 CTR3(KTR_SCHED, "mi_switch: running %p(%s) prio %d", 466 td, td->td_proc->p_comm, td->td_priority); 467 468 CTR4(KTR_PROC, "mi_switch: new thread %ld (kse %p, pid %ld, %s)", 469 td->td_tid, td->td_sched, p->p_pid, p->p_comm); 470 471 /* 472 * If the last thread was exiting, finish cleaning it up. 473 */ 474 if ((td = PCPU_GET(deadthread))) { 475 PCPU_SET(deadthread, NULL); 476 thread_stash(td); 477 } 478 } 479 480 /* 481 * Change process state to be runnable, 482 * placing it on the run queue if it is in memory, 483 * and awakening the swapper if it isn't in memory. 484 */ 485 void 486 setrunnable(struct thread *td) 487 { 488 struct proc *p; 489 490 p = td->td_proc; 491 mtx_assert(&sched_lock, MA_OWNED); 492 switch (p->p_state) { 493 case PRS_ZOMBIE: 494 panic("setrunnable(1)"); 495 default: 496 break; 497 } 498 switch (td->td_state) { 499 case TDS_RUNNING: 500 case TDS_RUNQ: 501 return; 502 case TDS_INHIBITED: 503 /* 504 * If we are only inhibited because we are swapped out 505 * then arange to swap in this process. Otherwise just return. 506 */ 507 if (td->td_inhibitors != TDI_SWAPPED) 508 return; 509 /* XXX: intentional fall-through ? */ 510 case TDS_CAN_RUN: 511 break; 512 default: 513 printf("state is 0x%x", td->td_state); 514 panic("setrunnable(2)"); 515 } 516 if ((p->p_sflag & PS_INMEM) == 0) { 517 if ((p->p_sflag & PS_SWAPPINGIN) == 0) { 518 p->p_sflag |= PS_SWAPINREQ; 519 /* 520 * due to a LOR between sched_lock and 521 * the sleepqueue chain locks, use 522 * lower level scheduling functions. 523 */ 524 kick_proc0(); 525 } 526 } else 527 sched_wakeup(td); 528 } 529 530 /* 531 * Compute a tenex style load average of a quantity on 532 * 1, 5 and 15 minute intervals. 533 * XXXKSE Needs complete rewrite when correct info is available. 534 * Completely Bogus.. only works with 1:1 (but compiles ok now :-) 535 */ 536 static void 537 loadav(void *arg) 538 { 539 int i, nrun; 540 struct loadavg *avg; 541 542 nrun = sched_load(); 543 avg = &averunnable; 544 545 for (i = 0; i < 3; i++) 546 avg->ldavg[i] = (cexp[i] * avg->ldavg[i] + 547 nrun * FSCALE * (FSCALE - cexp[i])) >> FSHIFT; 548 549 /* 550 * Schedule the next update to occur after 5 seconds, but add a 551 * random variation to avoid synchronisation with processes that 552 * run at regular intervals. 553 */ 554 callout_reset(&loadav_callout, hz * 4 + (int)(random() % (hz * 2 + 1)), 555 loadav, NULL); 556 } 557 558 static void 559 lboltcb(void *arg) 560 { 561 wakeup(&lbolt); 562 callout_reset(&lbolt_callout, hz, lboltcb, NULL); 563 } 564 565 /* ARGSUSED */ 566 static void 567 synch_setup(dummy) 568 void *dummy; 569 { 570 callout_init(&loadav_callout, CALLOUT_MPSAFE); 571 callout_init(&lbolt_callout, CALLOUT_MPSAFE); 572 573 /* Kick off timeout driven events by calling first time. */ 574 loadav(NULL); 575 lboltcb(NULL); 576 } 577 578 /* 579 * General purpose yield system call. 580 */ 581 int 582 yield(struct thread *td, struct yield_args *uap) 583 { 584 mtx_assert(&Giant, MA_NOTOWNED); 585 (void)uap; 586 sched_relinquish(td); 587 return (0); 588 } 589