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 73 static struct callout loadav_callout; 74 static struct callout lbolt_callout; 75 76 struct loadavg averunnable = 77 { {0, 0, 0}, FSCALE }; /* load average, of runnable procs */ 78 /* 79 * Constants for averages over 1, 5, and 15 minutes 80 * when sampling at 5 second intervals. 81 */ 82 static fixpt_t cexp[3] = { 83 0.9200444146293232 * FSCALE, /* exp(-1/12) */ 84 0.9834714538216174 * FSCALE, /* exp(-1/60) */ 85 0.9944598480048967 * FSCALE, /* exp(-1/180) */ 86 }; 87 88 /* kernel uses `FSCALE', userland (SHOULD) use kern.fscale */ 89 static int fscale __unused = FSCALE; 90 SYSCTL_INT(_kern, OID_AUTO, fscale, CTLFLAG_RD, 0, FSCALE, ""); 91 92 static void loadav(void *arg); 93 static void lboltcb(void *arg); 94 95 void 96 sleepinit(void) 97 { 98 99 hogticks = (hz / 10) * 2; /* Default only. */ 100 init_sleepqueues(); 101 } 102 103 /* 104 * General sleep call. Suspends the current thread until a wakeup is 105 * performed on the specified identifier. The thread will then be made 106 * runnable with the specified priority. Sleeps at most timo/hz seconds 107 * (0 means no timeout). If pri includes PCATCH flag, signals are checked 108 * before and after sleeping, else signals are not checked. Returns 0 if 109 * awakened, EWOULDBLOCK if the timeout expires. If PCATCH is set and a 110 * signal needs to be delivered, ERESTART is returned if the current system 111 * call should be restarted if possible, and EINTR is returned if the system 112 * call should be interrupted by the signal (return EINTR). 113 * 114 * The mutex argument is unlocked before the caller is suspended, and 115 * re-locked before msleep returns. If priority includes the PDROP 116 * flag the mutex is not re-locked before returning. 117 */ 118 int 119 msleep(ident, mtx, priority, wmesg, timo) 120 void *ident; 121 struct mtx *mtx; 122 int priority, timo; 123 const char *wmesg; 124 { 125 struct thread *td; 126 struct proc *p; 127 int catch, rval, flags, pri; 128 WITNESS_SAVE_DECL(mtx); 129 130 td = curthread; 131 p = td->td_proc; 132 #ifdef KTRACE 133 if (KTRPOINT(td, KTR_CSW)) 134 ktrcsw(1, 0); 135 #endif 136 WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, mtx == NULL ? NULL : 137 &mtx->mtx_object, "Sleeping on \"%s\"", wmesg); 138 KASSERT(timo != 0 || mtx_owned(&Giant) || mtx != NULL || 139 ident == &lbolt, ("sleeping without a mutex")); 140 KASSERT(p != NULL, ("msleep1")); 141 KASSERT(ident != NULL && TD_IS_RUNNING(td), ("msleep")); 142 143 if (cold) { 144 /* 145 * During autoconfiguration, just return; 146 * don't run any other threads or panic below, 147 * in case this is the idle thread and already asleep. 148 * XXX: this used to do "s = splhigh(); splx(safepri); 149 * splx(s);" to give interrupts a chance, but there is 150 * no way to give interrupts a chance now. 151 */ 152 if (mtx != NULL && priority & PDROP) 153 mtx_unlock(mtx); 154 return (0); 155 } 156 catch = priority & PCATCH; 157 rval = 0; 158 159 /* 160 * If we are already on a sleep queue, then remove us from that 161 * sleep queue first. We have to do this to handle recursive 162 * sleeps. 163 */ 164 if (TD_ON_SLEEPQ(td)) 165 sleepq_remove(td, td->td_wchan); 166 167 flags = SLEEPQ_MSLEEP; 168 if (catch) 169 flags |= SLEEPQ_INTERRUPTIBLE; 170 171 sleepq_lock(ident); 172 CTR5(KTR_PROC, "msleep: thread %p (pid %ld, %s) on %s (%p)", 173 (void *)td, (long)p->p_pid, p->p_comm, wmesg, ident); 174 175 DROP_GIANT(); 176 if (mtx != NULL) { 177 mtx_assert(mtx, MA_OWNED | MA_NOTRECURSED); 178 WITNESS_SAVE(&mtx->mtx_object, mtx); 179 mtx_unlock(mtx); 180 } 181 182 /* 183 * We put ourselves on the sleep queue and start our timeout 184 * before calling thread_suspend_check, as we could stop there, 185 * and a wakeup or a SIGCONT (or both) could occur while we were 186 * stopped without resuming us. Thus, we must be ready for sleep 187 * when cursig() is called. If the wakeup happens while we're 188 * stopped, then td will no longer be on a sleep queue upon 189 * return from cursig(). 190 */ 191 sleepq_add(ident, ident == &lbolt ? NULL : &mtx->mtx_object, wmesg, 192 flags, 0); 193 if (timo) 194 sleepq_set_timeout(ident, timo); 195 196 /* 197 * Adjust this thread's priority, if necessary. 198 */ 199 pri = priority & PRIMASK; 200 if (pri != 0 && pri != td->td_priority) { 201 mtx_lock_spin(&sched_lock); 202 sched_prio(td, pri); 203 mtx_unlock_spin(&sched_lock); 204 } 205 206 if (timo && catch) 207 rval = sleepq_timedwait_sig(ident); 208 else if (timo) 209 rval = sleepq_timedwait(ident); 210 else if (catch) 211 rval = sleepq_wait_sig(ident); 212 else { 213 sleepq_wait(ident); 214 rval = 0; 215 } 216 #ifdef KTRACE 217 if (KTRPOINT(td, KTR_CSW)) 218 ktrcsw(0, 0); 219 #endif 220 PICKUP_GIANT(); 221 if (mtx != NULL && !(priority & PDROP)) { 222 mtx_lock(mtx); 223 WITNESS_RESTORE(&mtx->mtx_object, mtx); 224 } 225 return (rval); 226 } 227 228 int 229 msleep_spin(ident, mtx, wmesg, timo) 230 void *ident; 231 struct mtx *mtx; 232 const char *wmesg; 233 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 %p (pid %ld, %s) on %s (%p)", 260 (void *)td, (long)p->p_pid, p->p_comm, wmesg, ident); 261 262 DROP_GIANT(); 263 mtx_assert(mtx, MA_OWNED | MA_NOTRECURSED); 264 WITNESS_SAVE(&mtx->mtx_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->mtx_object, wmesg, SLEEPQ_MSLEEP, 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); 296 else { 297 sleepq_wait(ident); 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->mtx_object, mtx); 307 return (rval); 308 } 309 310 /* 311 * Make all threads sleeping on the specified identifier runnable. 312 */ 313 void 314 wakeup(ident) 315 register void *ident; 316 { 317 318 sleepq_lock(ident); 319 sleepq_broadcast(ident, SLEEPQ_MSLEEP, -1, 0); 320 } 321 322 /* 323 * Make a thread sleeping on the specified identifier runnable. 324 * May wake more than one thread if a target thread is currently 325 * swapped out. 326 */ 327 void 328 wakeup_one(ident) 329 register void *ident; 330 { 331 332 sleepq_lock(ident); 333 sleepq_signal(ident, SLEEPQ_MSLEEP, -1, 0); 334 } 335 336 /* 337 * The machine independent parts of context switching. 338 */ 339 void 340 mi_switch(int flags, struct thread *newtd) 341 { 342 uint64_t new_switchtime; 343 struct thread *td; 344 struct proc *p; 345 346 mtx_assert(&sched_lock, MA_OWNED | MA_NOTRECURSED); 347 td = curthread; /* XXX */ 348 p = td->td_proc; /* XXX */ 349 KASSERT(!TD_ON_RUNQ(td), ("mi_switch: called by old code")); 350 #ifdef INVARIANTS 351 if (!TD_ON_LOCK(td) && !TD_IS_RUNNING(td)) 352 mtx_assert(&Giant, MA_NOTOWNED); 353 #endif 354 KASSERT(td->td_critnest == 1 || (td->td_critnest == 2 && 355 (td->td_owepreempt) && (flags & SW_INVOL) != 0 && 356 newtd == NULL) || panicstr, 357 ("mi_switch: switch in a critical section")); 358 KASSERT((flags & (SW_INVOL | SW_VOL)) != 0, 359 ("mi_switch: switch must be voluntary or involuntary")); 360 KASSERT(newtd != curthread, ("mi_switch: preempting back to ourself")); 361 362 /* 363 * Don't perform context switches from the debugger. 364 */ 365 if (kdb_active) { 366 mtx_unlock_spin(&sched_lock); 367 kdb_backtrace(); 368 kdb_reenter(); 369 panic("%s: did not reenter debugger", __func__); 370 } 371 372 if (flags & SW_VOL) 373 p->p_stats->p_ru.ru_nvcsw++; 374 else 375 p->p_stats->p_ru.ru_nivcsw++; 376 377 /* 378 * Compute the amount of time during which the current 379 * process was running, and add that to its total so far. 380 */ 381 new_switchtime = cpu_ticks(); 382 p->p_rux.rux_runtime += (new_switchtime - PCPU_GET(switchtime)); 383 p->p_rux.rux_uticks += td->td_uticks; 384 td->td_uticks = 0; 385 p->p_rux.rux_iticks += td->td_iticks; 386 td->td_iticks = 0; 387 p->p_rux.rux_sticks += td->td_sticks; 388 td->td_sticks = 0; 389 390 td->td_generation++; /* bump preempt-detect counter */ 391 392 /* 393 * Check if the process exceeds its cpu resource allocation. If 394 * it reaches the max, arrange to kill the process in ast(). 395 */ 396 if (p->p_cpulimit != RLIM_INFINITY && 397 p->p_rux.rux_runtime >= p->p_cpulimit * cpu_tickrate()) { 398 p->p_sflag |= PS_XCPU; 399 td->td_flags |= TDF_ASTPENDING; 400 } 401 402 /* 403 * Finish up stats for outgoing thread. 404 */ 405 cnt.v_swtch++; 406 PCPU_SET(switchtime, new_switchtime); 407 PCPU_SET(switchticks, ticks); 408 CTR4(KTR_PROC, "mi_switch: old thread %p (kse %p, pid %ld, %s)", 409 (void *)td, td->td_sched, (long)p->p_pid, p->p_comm); 410 #if (KTR_COMPILE & KTR_SCHED) != 0 411 if (td == PCPU_GET(idlethread)) 412 CTR3(KTR_SCHED, "mi_switch: %p(%s) prio %d idle", 413 td, td->td_proc->p_comm, td->td_priority); 414 else if (newtd != NULL) 415 CTR5(KTR_SCHED, 416 "mi_switch: %p(%s) prio %d preempted by %p(%s)", 417 td, td->td_proc->p_comm, td->td_priority, newtd, 418 newtd->td_proc->p_comm); 419 else 420 CTR6(KTR_SCHED, 421 "mi_switch: %p(%s) prio %d inhibit %d wmesg %s lock %s", 422 td, td->td_proc->p_comm, td->td_priority, 423 td->td_inhibitors, td->td_wmesg, td->td_lockname); 424 #endif 425 /* 426 * We call thread_switchout after the KTR_SCHED prints above so kse 427 * selecting a new thread to run does not show up as a preemption. 428 */ 429 #ifdef KSE 430 if ((flags & SW_VOL) && (td->td_proc->p_flag & P_SA)) 431 newtd = thread_switchout(td, flags, newtd); 432 #endif 433 sched_switch(td, newtd, flags); 434 CTR3(KTR_SCHED, "mi_switch: running %p(%s) prio %d", 435 td, td->td_proc->p_comm, td->td_priority); 436 437 CTR4(KTR_PROC, "mi_switch: new thread %p (kse %p, pid %ld, %s)", 438 (void *)td, td->td_sched, (long)p->p_pid, p->p_comm); 439 440 /* 441 * If the last thread was exiting, finish cleaning it up. 442 */ 443 if ((td = PCPU_GET(deadthread))) { 444 PCPU_SET(deadthread, NULL); 445 thread_stash(td); 446 } 447 } 448 449 /* 450 * Change process state to be runnable, 451 * placing it on the run queue if it is in memory, 452 * and awakening the swapper if it isn't in memory. 453 */ 454 void 455 setrunnable(struct thread *td) 456 { 457 struct proc *p; 458 459 p = td->td_proc; 460 mtx_assert(&sched_lock, MA_OWNED); 461 switch (p->p_state) { 462 case PRS_ZOMBIE: 463 panic("setrunnable(1)"); 464 default: 465 break; 466 } 467 switch (td->td_state) { 468 case TDS_RUNNING: 469 case TDS_RUNQ: 470 return; 471 case TDS_INHIBITED: 472 /* 473 * If we are only inhibited because we are swapped out 474 * then arange to swap in this process. Otherwise just return. 475 */ 476 if (td->td_inhibitors != TDI_SWAPPED) 477 return; 478 /* XXX: intentional fall-through ? */ 479 case TDS_CAN_RUN: 480 break; 481 default: 482 printf("state is 0x%x", td->td_state); 483 panic("setrunnable(2)"); 484 } 485 if ((p->p_sflag & PS_INMEM) == 0) { 486 if ((p->p_sflag & PS_SWAPPINGIN) == 0) { 487 p->p_sflag |= PS_SWAPINREQ; 488 /* 489 * due to a LOR between sched_lock and 490 * the sleepqueue chain locks, use 491 * lower level scheduling functions. 492 */ 493 kick_proc0(); 494 } 495 } else 496 sched_wakeup(td); 497 } 498 499 /* 500 * Compute a tenex style load average of a quantity on 501 * 1, 5 and 15 minute intervals. 502 * XXXKSE Needs complete rewrite when correct info is available. 503 * Completely Bogus.. only works with 1:1 (but compiles ok now :-) 504 */ 505 static void 506 loadav(void *arg) 507 { 508 int i, nrun; 509 struct loadavg *avg; 510 511 nrun = sched_load(); 512 avg = &averunnable; 513 514 for (i = 0; i < 3; i++) 515 avg->ldavg[i] = (cexp[i] * avg->ldavg[i] + 516 nrun * FSCALE * (FSCALE - cexp[i])) >> FSHIFT; 517 518 /* 519 * Schedule the next update to occur after 5 seconds, but add a 520 * random variation to avoid synchronisation with processes that 521 * run at regular intervals. 522 */ 523 callout_reset(&loadav_callout, hz * 4 + (int)(random() % (hz * 2 + 1)), 524 loadav, NULL); 525 } 526 527 static void 528 lboltcb(void *arg) 529 { 530 wakeup(&lbolt); 531 callout_reset(&lbolt_callout, hz, lboltcb, NULL); 532 } 533 534 /* ARGSUSED */ 535 static void 536 synch_setup(dummy) 537 void *dummy; 538 { 539 callout_init(&loadav_callout, CALLOUT_MPSAFE); 540 callout_init(&lbolt_callout, CALLOUT_MPSAFE); 541 542 /* Kick off timeout driven events by calling first time. */ 543 loadav(NULL); 544 lboltcb(NULL); 545 } 546 547 /* 548 * General purpose yield system call 549 */ 550 int 551 yield(struct thread *td, struct yield_args *uap) 552 { 553 mtx_assert(&Giant, MA_NOTOWNED); 554 (void)uap; 555 sched_relinquish(td); 556 return (0); 557 } 558