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 #include "opt_sched.h" 42 43 #include <sys/param.h> 44 #include <sys/systm.h> 45 #include <sys/condvar.h> 46 #include <sys/kdb.h> 47 #include <sys/kernel.h> 48 #include <sys/ktr.h> 49 #include <sys/lock.h> 50 #include <sys/mutex.h> 51 #include <sys/proc.h> 52 #include <sys/resourcevar.h> 53 #include <sys/sched.h> 54 #include <sys/signalvar.h> 55 #include <sys/sleepqueue.h> 56 #include <sys/smp.h> 57 #include <sys/sx.h> 58 #include <sys/sysctl.h> 59 #include <sys/sysproto.h> 60 #include <sys/vmmeter.h> 61 #ifdef KTRACE 62 #include <sys/uio.h> 63 #include <sys/ktrace.h> 64 #endif 65 66 #include <machine/cpu.h> 67 68 static void synch_setup(void *dummy); 69 SYSINIT(synch_setup, SI_SUB_KICK_SCHEDULER, SI_ORDER_FIRST, synch_setup, 70 NULL); 71 72 int hogticks; 73 int lbolt; 74 static int pause_wchan; 75 76 static struct callout loadav_callout; 77 static struct callout lbolt_callout; 78 79 struct loadavg averunnable = 80 { {0, 0, 0}, FSCALE }; /* load average, of runnable procs */ 81 /* 82 * Constants for averages over 1, 5, and 15 minutes 83 * when sampling at 5 second intervals. 84 */ 85 static fixpt_t cexp[3] = { 86 0.9200444146293232 * FSCALE, /* exp(-1/12) */ 87 0.9834714538216174 * FSCALE, /* exp(-1/60) */ 88 0.9944598480048967 * FSCALE, /* exp(-1/180) */ 89 }; 90 91 /* kernel uses `FSCALE', userland (SHOULD) use kern.fscale */ 92 static int fscale __unused = FSCALE; 93 SYSCTL_INT(_kern, OID_AUTO, fscale, CTLFLAG_RD, 0, FSCALE, ""); 94 95 static void loadav(void *arg); 96 static void lboltcb(void *arg); 97 98 void 99 sleepinit(void) 100 { 101 102 hogticks = (hz / 10) * 2; /* Default only. */ 103 init_sleepqueues(); 104 } 105 106 /* 107 * General sleep call. Suspends the current thread until a wakeup is 108 * performed on the specified identifier. The thread will then be made 109 * runnable with the specified priority. Sleeps at most timo/hz seconds 110 * (0 means no timeout). If pri includes PCATCH flag, signals are checked 111 * before and after sleeping, else signals are not checked. Returns 0 if 112 * awakened, EWOULDBLOCK if the timeout expires. If PCATCH is set and a 113 * signal needs to be delivered, ERESTART is returned if the current system 114 * call should be restarted if possible, and EINTR is returned if the system 115 * call should be interrupted by the signal (return EINTR). 116 * 117 * The lock argument is unlocked before the caller is suspended, and 118 * re-locked before _sleep() returns. If priority includes the PDROP 119 * flag the lock is not re-locked before returning. 120 */ 121 int 122 _sleep(void *ident, struct lock_object *lock, int priority, 123 const char *wmesg, int timo) 124 { 125 struct thread *td; 126 struct proc *p; 127 struct lock_class *class; 128 int catch, flags, lock_state, pri, rval; 129 WITNESS_SAVE_DECL(lock_witness); 130 131 td = curthread; 132 p = td->td_proc; 133 #ifdef KTRACE 134 if (KTRPOINT(td, KTR_CSW)) 135 ktrcsw(1, 0); 136 #endif 137 WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, lock, 138 "Sleeping on \"%s\"", wmesg); 139 KASSERT(timo != 0 || mtx_owned(&Giant) || lock != NULL || 140 ident == &lbolt, ("sleeping without a lock")); 141 KASSERT(p != NULL, ("msleep1")); 142 KASSERT(ident != NULL && TD_IS_RUNNING(td), ("msleep")); 143 if (lock != NULL) 144 class = LOCK_CLASS(lock); 145 else 146 class = NULL; 147 148 if (cold) { 149 /* 150 * During autoconfiguration, just return; 151 * don't run any other threads or panic below, 152 * in case this is the idle thread and already asleep. 153 * XXX: this used to do "s = splhigh(); splx(safepri); 154 * splx(s);" to give interrupts a chance, but there is 155 * no way to give interrupts a chance now. 156 */ 157 if (lock != NULL && priority & PDROP) 158 class->lc_unlock(lock); 159 return (0); 160 } 161 catch = priority & PCATCH; 162 pri = priority & PRIMASK; 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, td->td_name, 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 if (timo && catch) 211 rval = sleepq_timedwait_sig(ident, pri); 212 else if (timo) 213 rval = sleepq_timedwait(ident, pri); 214 else if (catch) 215 rval = sleepq_wait_sig(ident, pri); 216 else { 217 sleepq_wait(ident, pri); 218 rval = 0; 219 } 220 #ifdef KTRACE 221 if (KTRPOINT(td, KTR_CSW)) 222 ktrcsw(0, 0); 223 #endif 224 PICKUP_GIANT(); 225 if (lock != NULL && !(priority & PDROP)) { 226 class->lc_lock(lock, lock_state); 227 WITNESS_RESTORE(lock, lock_witness); 228 } 229 return (rval); 230 } 231 232 int 233 msleep_spin(void *ident, struct mtx *mtx, const char *wmesg, int timo) 234 { 235 struct thread *td; 236 struct proc *p; 237 int rval; 238 WITNESS_SAVE_DECL(mtx); 239 240 td = curthread; 241 p = td->td_proc; 242 KASSERT(mtx != NULL, ("sleeping without a mutex")); 243 KASSERT(p != NULL, ("msleep1")); 244 KASSERT(ident != NULL && TD_IS_RUNNING(td), ("msleep")); 245 246 if (cold) { 247 /* 248 * During autoconfiguration, just return; 249 * don't run any other threads or panic below, 250 * in case this is the idle thread and already asleep. 251 * XXX: this used to do "s = splhigh(); splx(safepri); 252 * splx(s);" to give interrupts a chance, but there is 253 * no way to give interrupts a chance now. 254 */ 255 return (0); 256 } 257 258 sleepq_lock(ident); 259 CTR5(KTR_PROC, "msleep_spin: thread %ld (pid %ld, %s) on %s (%p)", 260 td->td_tid, p->p_pid, td->td_name, wmesg, ident); 261 262 DROP_GIANT(); 263 mtx_assert(mtx, MA_OWNED | MA_NOTRECURSED); 264 WITNESS_SAVE(&mtx->lock_object, mtx); 265 mtx_unlock_spin(mtx); 266 267 /* 268 * We put ourselves on the sleep queue and start our timeout. 269 */ 270 sleepq_add(ident, &mtx->lock_object, wmesg, SLEEPQ_SLEEP, 0); 271 if (timo) 272 sleepq_set_timeout(ident, timo); 273 274 /* 275 * Can't call ktrace with any spin locks held so it can lock the 276 * ktrace_mtx lock, and WITNESS_WARN considers it an error to hold 277 * any spin lock. Thus, we have to drop the sleepq spin lock while 278 * we handle those requests. This is safe since we have placed our 279 * thread on the sleep queue already. 280 */ 281 #ifdef KTRACE 282 if (KTRPOINT(td, KTR_CSW)) { 283 sleepq_release(ident); 284 ktrcsw(1, 0); 285 sleepq_lock(ident); 286 } 287 #endif 288 #ifdef WITNESS 289 sleepq_release(ident); 290 WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, NULL, "Sleeping on \"%s\"", 291 wmesg); 292 sleepq_lock(ident); 293 #endif 294 if (timo) 295 rval = sleepq_timedwait(ident, 0); 296 else { 297 sleepq_wait(ident, 0); 298 rval = 0; 299 } 300 #ifdef KTRACE 301 if (KTRPOINT(td, KTR_CSW)) 302 ktrcsw(0, 0); 303 #endif 304 PICKUP_GIANT(); 305 mtx_lock_spin(mtx); 306 WITNESS_RESTORE(&mtx->lock_object, mtx); 307 return (rval); 308 } 309 310 /* 311 * pause() is like tsleep() except that the intention is to not be 312 * explicitly woken up by another thread. Instead, the current thread 313 * simply wishes to sleep until the timeout expires. It is 314 * implemented using a dummy wait channel. 315 */ 316 int 317 pause(const char *wmesg, int timo) 318 { 319 320 KASSERT(timo != 0, ("pause: timeout required")); 321 return (tsleep(&pause_wchan, 0, wmesg, timo)); 322 } 323 324 /* 325 * Make all threads sleeping on the specified identifier runnable. 326 */ 327 void 328 wakeup(void *ident) 329 { 330 int wakeup_swapper; 331 332 sleepq_lock(ident); 333 wakeup_swapper = sleepq_broadcast(ident, SLEEPQ_SLEEP, 0, 0); 334 sleepq_release(ident); 335 if (wakeup_swapper) 336 kick_proc0(); 337 } 338 339 /* 340 * Make a thread sleeping on the specified identifier runnable. 341 * May wake more than one thread if a target thread is currently 342 * swapped out. 343 */ 344 void 345 wakeup_one(void *ident) 346 { 347 int wakeup_swapper; 348 349 sleepq_lock(ident); 350 wakeup_swapper = sleepq_signal(ident, SLEEPQ_SLEEP, 0, 0); 351 sleepq_release(ident); 352 if (wakeup_swapper) 353 kick_proc0(); 354 } 355 356 static void 357 kdb_switch(void) 358 { 359 thread_unlock(curthread); 360 kdb_backtrace(); 361 kdb_reenter(); 362 panic("%s: did not reenter debugger", __func__); 363 } 364 365 /* 366 * The machine independent parts of context switching. 367 */ 368 void 369 mi_switch(int flags, struct thread *newtd) 370 { 371 uint64_t runtime, new_switchtime; 372 struct thread *td; 373 struct proc *p; 374 375 td = curthread; /* XXX */ 376 THREAD_LOCK_ASSERT(td, MA_OWNED | MA_NOTRECURSED); 377 p = td->td_proc; /* XXX */ 378 KASSERT(!TD_ON_RUNQ(td), ("mi_switch: called by old code")); 379 #ifdef INVARIANTS 380 if (!TD_ON_LOCK(td) && !TD_IS_RUNNING(td)) 381 mtx_assert(&Giant, MA_NOTOWNED); 382 #endif 383 KASSERT(td->td_critnest == 1 || (td->td_critnest == 2 && 384 (td->td_owepreempt) && (flags & SW_INVOL) != 0 && 385 newtd == NULL) || panicstr, 386 ("mi_switch: switch in a critical section")); 387 KASSERT((flags & (SW_INVOL | SW_VOL)) != 0, 388 ("mi_switch: switch must be voluntary or involuntary")); 389 KASSERT(newtd != curthread, ("mi_switch: preempting back to ourself")); 390 391 /* 392 * Don't perform context switches from the debugger. 393 */ 394 if (kdb_active) 395 kdb_switch(); 396 if (flags & SW_VOL) 397 td->td_ru.ru_nvcsw++; 398 else 399 td->td_ru.ru_nivcsw++; 400 #ifdef SCHED_STATS 401 SCHED_STAT_INC(sched_switch_stats[flags & SW_TYPE_MASK]); 402 #endif 403 /* 404 * Compute the amount of time during which the current 405 * thread was running, and add that to its total so far. 406 */ 407 new_switchtime = cpu_ticks(); 408 runtime = new_switchtime - PCPU_GET(switchtime); 409 td->td_runtime += runtime; 410 td->td_incruntime += runtime; 411 PCPU_SET(switchtime, new_switchtime); 412 td->td_generation++; /* bump preempt-detect counter */ 413 PCPU_INC(cnt.v_swtch); 414 PCPU_SET(switchticks, ticks); 415 CTR4(KTR_PROC, "mi_switch: old thread %ld (td_sched %p, pid %ld, %s)", 416 td->td_tid, td->td_sched, p->p_pid, td->td_name); 417 #if (KTR_COMPILE & KTR_SCHED) != 0 418 if (TD_IS_IDLETHREAD(td)) 419 CTR3(KTR_SCHED, "mi_switch: %p(%s) prio %d idle", 420 td, td->td_name, td->td_priority); 421 else if (newtd != NULL) 422 CTR5(KTR_SCHED, 423 "mi_switch: %p(%s) prio %d preempted by %p(%s)", 424 td, td->td_name, td->td_priority, newtd, 425 newtd->td_name); 426 else 427 CTR6(KTR_SCHED, 428 "mi_switch: %p(%s) prio %d inhibit %d wmesg %s lock %s", 429 td, td->td_name, td->td_priority, 430 td->td_inhibitors, td->td_wmesg, td->td_lockname); 431 #endif 432 sched_switch(td, newtd, flags); 433 CTR3(KTR_SCHED, "mi_switch: running %p(%s) prio %d", 434 td, td->td_name, td->td_priority); 435 436 CTR4(KTR_PROC, "mi_switch: new thread %ld (td_sched %p, pid %ld, %s)", 437 td->td_tid, td->td_sched, p->p_pid, td->td_name); 438 439 /* 440 * If the last thread was exiting, finish cleaning it up. 441 */ 442 if ((td = PCPU_GET(deadthread))) { 443 PCPU_SET(deadthread, NULL); 444 thread_stash(td); 445 } 446 } 447 448 /* 449 * Change thread state to be runnable, placing it on the run queue if 450 * it is in memory. If it is swapped out, return true so our caller 451 * will know to awaken the swapper. 452 */ 453 int 454 setrunnable(struct thread *td) 455 { 456 457 THREAD_LOCK_ASSERT(td, MA_OWNED); 458 KASSERT(td->td_proc->p_state != PRS_ZOMBIE, 459 ("setrunnable: pid %d is a zombie", td->td_proc->p_pid)); 460 switch (td->td_state) { 461 case TDS_RUNNING: 462 case TDS_RUNQ: 463 return (0); 464 case TDS_INHIBITED: 465 /* 466 * If we are only inhibited because we are swapped out 467 * then arange to swap in this process. Otherwise just return. 468 */ 469 if (td->td_inhibitors != TDI_SWAPPED) 470 return (0); 471 /* FALLTHROUGH */ 472 case TDS_CAN_RUN: 473 break; 474 default: 475 printf("state is 0x%x", td->td_state); 476 panic("setrunnable(2)"); 477 } 478 if ((td->td_flags & TDF_INMEM) == 0) { 479 if ((td->td_flags & TDF_SWAPINREQ) == 0) { 480 td->td_flags |= TDF_SWAPINREQ; 481 return (1); 482 } 483 } else 484 sched_wakeup(td); 485 return (0); 486 } 487 488 /* 489 * Compute a tenex style load average of a quantity on 490 * 1, 5 and 15 minute intervals. 491 */ 492 static void 493 loadav(void *arg) 494 { 495 int i, nrun; 496 struct loadavg *avg; 497 498 nrun = sched_load(); 499 avg = &averunnable; 500 501 for (i = 0; i < 3; i++) 502 avg->ldavg[i] = (cexp[i] * avg->ldavg[i] + 503 nrun * FSCALE * (FSCALE - cexp[i])) >> FSHIFT; 504 505 /* 506 * Schedule the next update to occur after 5 seconds, but add a 507 * random variation to avoid synchronisation with processes that 508 * run at regular intervals. 509 */ 510 callout_reset(&loadav_callout, hz * 4 + (int)(random() % (hz * 2 + 1)), 511 loadav, NULL); 512 } 513 514 static void 515 lboltcb(void *arg) 516 { 517 wakeup(&lbolt); 518 callout_reset(&lbolt_callout, hz, lboltcb, NULL); 519 } 520 521 /* ARGSUSED */ 522 static void 523 synch_setup(void *dummy) 524 { 525 callout_init(&loadav_callout, CALLOUT_MPSAFE); 526 callout_init(&lbolt_callout, CALLOUT_MPSAFE); 527 528 /* Kick off timeout driven events by calling first time. */ 529 loadav(NULL); 530 lboltcb(NULL); 531 } 532 533 /* 534 * General purpose yield system call. 535 */ 536 int 537 yield(struct thread *td, struct yield_args *uap) 538 { 539 540 thread_lock(td); 541 sched_prio(td, PRI_MAX_TIMESHARE); 542 mi_switch(SW_VOL | SWT_RELINQUISH, NULL); 543 thread_unlock(td); 544 td->td_retval[0] = 0; 545 return (0); 546 } 547