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 * 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 * @(#)kern_synch.c 8.9 (Berkeley) 5/19/95 39 */ 40 41 #include <sys/cdefs.h> 42 __FBSDID("$FreeBSD$"); 43 44 #include "opt_ddb.h" 45 #include "opt_ktrace.h" 46 #ifdef __i386__ 47 #include "opt_swtch.h" 48 #endif 49 50 #include <sys/param.h> 51 #include <sys/systm.h> 52 #include <sys/condvar.h> 53 #include <sys/kernel.h> 54 #include <sys/ktr.h> 55 #include <sys/lock.h> 56 #include <sys/mutex.h> 57 #include <sys/proc.h> 58 #include <sys/resourcevar.h> 59 #include <sys/sched.h> 60 #include <sys/signalvar.h> 61 #include <sys/smp.h> 62 #include <sys/sx.h> 63 #include <sys/sysctl.h> 64 #include <sys/sysproto.h> 65 #include <sys/vmmeter.h> 66 #ifdef DDB 67 #include <ddb/ddb.h> 68 #endif 69 #ifdef KTRACE 70 #include <sys/uio.h> 71 #include <sys/ktrace.h> 72 #endif 73 74 #include <machine/cpu.h> 75 76 static void sched_setup(void *dummy); 77 SYSINIT(sched_setup, SI_SUB_KICK_SCHEDULER, SI_ORDER_FIRST, sched_setup, NULL) 78 79 int hogticks; 80 int lbolt; 81 82 static struct callout loadav_callout; 83 static struct callout lbolt_callout; 84 85 struct loadavg averunnable = 86 { {0, 0, 0}, FSCALE }; /* load average, of runnable procs */ 87 /* 88 * Constants for averages over 1, 5, and 15 minutes 89 * when sampling at 5 second intervals. 90 */ 91 static fixpt_t cexp[3] = { 92 0.9200444146293232 * FSCALE, /* exp(-1/12) */ 93 0.9834714538216174 * FSCALE, /* exp(-1/60) */ 94 0.9944598480048967 * FSCALE, /* exp(-1/180) */ 95 }; 96 97 /* kernel uses `FSCALE', userland (SHOULD) use kern.fscale */ 98 static int fscale __unused = FSCALE; 99 SYSCTL_INT(_kern, OID_AUTO, fscale, CTLFLAG_RD, 0, FSCALE, ""); 100 101 static void endtsleep(void *); 102 static void loadav(void *arg); 103 static void lboltcb(void *arg); 104 105 /* 106 * We're only looking at 7 bits of the address; everything is 107 * aligned to 4, lots of things are aligned to greater powers 108 * of 2. Shift right by 8, i.e. drop the bottom 256 worth. 109 */ 110 #define TABLESIZE 128 111 static TAILQ_HEAD(slpquehead, thread) slpque[TABLESIZE]; 112 #define LOOKUP(x) (((intptr_t)(x) >> 8) & (TABLESIZE - 1)) 113 114 void 115 sleepinit(void) 116 { 117 int i; 118 119 hogticks = (hz / 10) * 2; /* Default only. */ 120 for (i = 0; i < TABLESIZE; i++) 121 TAILQ_INIT(&slpque[i]); 122 } 123 124 /* 125 * General sleep call. Suspends the current process until a wakeup is 126 * performed on the specified identifier. The process will then be made 127 * runnable with the specified priority. Sleeps at most timo/hz seconds 128 * (0 means no timeout). If pri includes PCATCH flag, signals are checked 129 * before and after sleeping, else signals are not checked. Returns 0 if 130 * awakened, EWOULDBLOCK if the timeout expires. If PCATCH is set and a 131 * signal needs to be delivered, ERESTART is returned if the current system 132 * call should be restarted if possible, and EINTR is returned if the system 133 * call should be interrupted by the signal (return EINTR). 134 * 135 * The mutex argument is exited before the caller is suspended, and 136 * entered before msleep returns. If priority includes the PDROP 137 * flag the mutex is not entered before returning. 138 */ 139 140 int 141 msleep(ident, mtx, priority, wmesg, timo) 142 void *ident; 143 struct mtx *mtx; 144 int priority, timo; 145 const char *wmesg; 146 { 147 struct thread *td = curthread; 148 struct proc *p = td->td_proc; 149 int sig, catch = priority & PCATCH; 150 int rval = 0; 151 WITNESS_SAVE_DECL(mtx); 152 153 #ifdef KTRACE 154 if (KTRPOINT(td, KTR_CSW)) 155 ktrcsw(1, 0); 156 #endif 157 /* XXX: mtx == NULL ?? */ 158 WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, &mtx->mtx_object, 159 "Sleeping on \"%s\"", wmesg); 160 KASSERT(timo != 0 || mtx_owned(&Giant) || mtx != NULL, 161 ("sleeping without a mutex")); 162 /* 163 * If we are capable of async syscalls and there isn't already 164 * another one ready to return, start a new thread 165 * and queue it as ready to run. Note that there is danger here 166 * because we need to make sure that we don't sleep allocating 167 * the thread (recursion here might be bad). 168 */ 169 mtx_lock_spin(&sched_lock); 170 if (p->p_flag & P_SA || p->p_numthreads > 1) { 171 /* 172 * Just don't bother if we are exiting 173 * and not the exiting thread or thread was marked as 174 * interrupted. 175 */ 176 if (catch) { 177 if ((p->p_flag & P_WEXIT) && p->p_singlethread != td) { 178 mtx_unlock_spin(&sched_lock); 179 return (EINTR); 180 } 181 if (td->td_flags & TDF_INTERRUPT) { 182 mtx_unlock_spin(&sched_lock); 183 return (td->td_intrval); 184 } 185 } 186 } 187 if (cold ) { 188 /* 189 * During autoconfiguration, just give interrupts 190 * a chance, then just return. 191 * Don't run any other procs or panic below, 192 * in case this is the idle process and already asleep. 193 */ 194 if (mtx != NULL && priority & PDROP) 195 mtx_unlock(mtx); 196 mtx_unlock_spin(&sched_lock); 197 return (0); 198 } 199 200 DROP_GIANT(); 201 202 if (mtx != NULL) { 203 mtx_assert(mtx, MA_OWNED | MA_NOTRECURSED); 204 WITNESS_SAVE(&mtx->mtx_object, mtx); 205 mtx_unlock(mtx); 206 if (priority & PDROP) 207 mtx = NULL; 208 } 209 210 KASSERT(p != NULL, ("msleep1")); 211 KASSERT(ident != NULL && TD_IS_RUNNING(td), ("msleep")); 212 213 CTR5(KTR_PROC, "msleep: thread %p (pid %d, %s) on %s (%p)", 214 td, p->p_pid, p->p_comm, wmesg, ident); 215 216 td->td_wchan = ident; 217 td->td_wmesg = wmesg; 218 TAILQ_INSERT_TAIL(&slpque[LOOKUP(ident)], td, td_slpq); 219 TD_SET_ON_SLEEPQ(td); 220 if (timo) 221 callout_reset(&td->td_slpcallout, timo, endtsleep, td); 222 /* 223 * We put ourselves on the sleep queue and start our timeout 224 * before calling thread_suspend_check, as we could stop there, and 225 * a wakeup or a SIGCONT (or both) could occur while we were stopped. 226 * without resuming us, thus we must be ready for sleep 227 * when cursig is called. If the wakeup happens while we're 228 * stopped, td->td_wchan will be 0 upon return from cursig. 229 */ 230 if (catch) { 231 CTR3(KTR_PROC, "msleep caught: thread %p (pid %d, %s)", td, 232 p->p_pid, p->p_comm); 233 td->td_flags |= TDF_SINTR; 234 mtx_unlock_spin(&sched_lock); 235 PROC_LOCK(p); 236 mtx_lock(&p->p_sigacts->ps_mtx); 237 sig = cursig(td); 238 mtx_unlock(&p->p_sigacts->ps_mtx); 239 if (sig == 0 && thread_suspend_check(1)) 240 sig = SIGSTOP; 241 mtx_lock_spin(&sched_lock); 242 PROC_UNLOCK(p); 243 if (sig != 0) { 244 if (TD_ON_SLEEPQ(td)) 245 unsleep(td); 246 } else if (!TD_ON_SLEEPQ(td)) 247 catch = 0; 248 } else 249 sig = 0; 250 251 /* 252 * Let the scheduler know we're about to voluntarily go to sleep. 253 */ 254 sched_sleep(td, priority & PRIMASK); 255 256 if (TD_ON_SLEEPQ(td)) { 257 p->p_stats->p_ru.ru_nvcsw++; 258 TD_SET_SLEEPING(td); 259 mi_switch(); 260 } 261 /* 262 * We're awake from voluntary sleep. 263 */ 264 CTR3(KTR_PROC, "msleep resume: thread %p (pid %d, %s)", td, p->p_pid, 265 p->p_comm); 266 KASSERT(TD_IS_RUNNING(td), ("running but not TDS_RUNNING")); 267 td->td_flags &= ~TDF_SINTR; 268 if (td->td_flags & TDF_TIMEOUT) { 269 td->td_flags &= ~TDF_TIMEOUT; 270 if (sig == 0) 271 rval = EWOULDBLOCK; 272 } else if (td->td_flags & TDF_TIMOFAIL) { 273 td->td_flags &= ~TDF_TIMOFAIL; 274 } else if (timo && callout_stop(&td->td_slpcallout) == 0) { 275 /* 276 * This isn't supposed to be pretty. If we are here, then 277 * the endtsleep() callout is currently executing on another 278 * CPU and is either spinning on the sched_lock or will be 279 * soon. If we don't synchronize here, there is a chance 280 * that this process may msleep() again before the callout 281 * has a chance to run and the callout may end up waking up 282 * the wrong msleep(). Yuck. 283 */ 284 TD_SET_SLEEPING(td); 285 p->p_stats->p_ru.ru_nivcsw++; 286 mi_switch(); 287 td->td_flags &= ~TDF_TIMOFAIL; 288 } 289 if ((td->td_flags & TDF_INTERRUPT) && (priority & PCATCH) && 290 (rval == 0)) { 291 rval = td->td_intrval; 292 } 293 mtx_unlock_spin(&sched_lock); 294 295 if (rval == 0 && catch) { 296 PROC_LOCK(p); 297 /* XXX: shouldn't we always be calling cursig() */ 298 mtx_lock(&p->p_sigacts->ps_mtx); 299 if (sig != 0 || (sig = cursig(td))) { 300 if (SIGISMEMBER(p->p_sigacts->ps_sigintr, sig)) 301 rval = EINTR; 302 else 303 rval = ERESTART; 304 } 305 mtx_unlock(&p->p_sigacts->ps_mtx); 306 PROC_UNLOCK(p); 307 } 308 #ifdef KTRACE 309 if (KTRPOINT(td, KTR_CSW)) 310 ktrcsw(0, 0); 311 #endif 312 PICKUP_GIANT(); 313 if (mtx != NULL) { 314 mtx_lock(mtx); 315 WITNESS_RESTORE(&mtx->mtx_object, mtx); 316 } 317 return (rval); 318 } 319 320 /* 321 * Implement timeout for msleep() 322 * 323 * If process hasn't been awakened (wchan non-zero), 324 * set timeout flag and undo the sleep. If proc 325 * is stopped, just unsleep so it will remain stopped. 326 * MP-safe, called without the Giant mutex. 327 */ 328 static void 329 endtsleep(arg) 330 void *arg; 331 { 332 register struct thread *td = arg; 333 334 CTR3(KTR_PROC, "endtsleep: thread %p (pid %d, %s)", 335 td, td->td_proc->p_pid, td->td_proc->p_comm); 336 mtx_lock_spin(&sched_lock); 337 /* 338 * This is the other half of the synchronization with msleep() 339 * described above. If the TDS_TIMEOUT flag is set, we lost the 340 * race and just need to put the process back on the runqueue. 341 */ 342 if (TD_ON_SLEEPQ(td)) { 343 TAILQ_REMOVE(&slpque[LOOKUP(td->td_wchan)], td, td_slpq); 344 TD_CLR_ON_SLEEPQ(td); 345 td->td_flags |= TDF_TIMEOUT; 346 td->td_wmesg = NULL; 347 } else { 348 td->td_flags |= TDF_TIMOFAIL; 349 } 350 TD_CLR_SLEEPING(td); 351 setrunnable(td); 352 mtx_unlock_spin(&sched_lock); 353 } 354 355 /* 356 * Abort a thread, as if an interrupt had occured. Only abort 357 * interruptable waits (unfortunatly it isn't only safe to abort others). 358 * This is about identical to cv_abort(). 359 * Think about merging them? 360 * Also, whatever the signal code does... 361 */ 362 void 363 abortsleep(struct thread *td) 364 { 365 366 mtx_assert(&sched_lock, MA_OWNED); 367 /* 368 * If the TDF_TIMEOUT flag is set, just leave. A 369 * timeout is scheduled anyhow. 370 */ 371 if ((td->td_flags & (TDF_TIMEOUT | TDF_SINTR)) == TDF_SINTR) { 372 if (TD_ON_SLEEPQ(td)) { 373 unsleep(td); 374 TD_CLR_SLEEPING(td); 375 setrunnable(td); 376 } 377 } 378 } 379 380 /* 381 * Remove a process from its wait queue 382 */ 383 void 384 unsleep(struct thread *td) 385 { 386 387 mtx_lock_spin(&sched_lock); 388 if (TD_ON_SLEEPQ(td)) { 389 TAILQ_REMOVE(&slpque[LOOKUP(td->td_wchan)], td, td_slpq); 390 TD_CLR_ON_SLEEPQ(td); 391 td->td_wmesg = NULL; 392 } 393 mtx_unlock_spin(&sched_lock); 394 } 395 396 /* 397 * Make all processes sleeping on the specified identifier runnable. 398 */ 399 void 400 wakeup(ident) 401 register void *ident; 402 { 403 register struct slpquehead *qp; 404 register struct thread *td; 405 struct thread *ntd; 406 struct proc *p; 407 408 mtx_lock_spin(&sched_lock); 409 qp = &slpque[LOOKUP(ident)]; 410 restart: 411 for (td = TAILQ_FIRST(qp); td != NULL; td = ntd) { 412 ntd = TAILQ_NEXT(td, td_slpq); 413 if (td->td_wchan == ident) { 414 unsleep(td); 415 TD_CLR_SLEEPING(td); 416 setrunnable(td); 417 p = td->td_proc; 418 CTR3(KTR_PROC,"wakeup: thread %p (pid %d, %s)", 419 td, p->p_pid, p->p_comm); 420 goto restart; 421 } 422 } 423 mtx_unlock_spin(&sched_lock); 424 } 425 426 /* 427 * Make a process sleeping on the specified identifier runnable. 428 * May wake more than one process if a target process is currently 429 * swapped out. 430 */ 431 void 432 wakeup_one(ident) 433 register void *ident; 434 { 435 register struct slpquehead *qp; 436 register struct thread *td; 437 register struct proc *p; 438 struct thread *ntd; 439 440 mtx_lock_spin(&sched_lock); 441 qp = &slpque[LOOKUP(ident)]; 442 for (td = TAILQ_FIRST(qp); td != NULL; td = ntd) { 443 ntd = TAILQ_NEXT(td, td_slpq); 444 if (td->td_wchan == ident) { 445 unsleep(td); 446 TD_CLR_SLEEPING(td); 447 setrunnable(td); 448 p = td->td_proc; 449 CTR3(KTR_PROC,"wakeup1: thread %p (pid %d, %s)", 450 td, p->p_pid, p->p_comm); 451 break; 452 } 453 } 454 mtx_unlock_spin(&sched_lock); 455 } 456 457 /* 458 * The machine independent parts of mi_switch(). 459 */ 460 void 461 mi_switch(void) 462 { 463 struct bintime new_switchtime; 464 struct thread *td; 465 #if !defined(__alpha__) && !defined(__powerpc__) 466 struct thread *newtd; 467 #endif 468 struct proc *p; 469 u_int sched_nest; 470 471 mtx_assert(&sched_lock, MA_OWNED | MA_NOTRECURSED); 472 td = curthread; /* XXX */ 473 p = td->td_proc; /* XXX */ 474 KASSERT(!TD_ON_RUNQ(td), ("mi_switch: called by old code")); 475 #ifdef INVARIANTS 476 if (!TD_ON_LOCK(td) && !TD_IS_RUNNING(td)) 477 mtx_assert(&Giant, MA_NOTOWNED); 478 #endif 479 KASSERT(td->td_critnest == 1, 480 ("mi_switch: switch in a critical section")); 481 482 /* 483 * Compute the amount of time during which the current 484 * process was running, and add that to its total so far. 485 */ 486 binuptime(&new_switchtime); 487 bintime_add(&p->p_runtime, &new_switchtime); 488 bintime_sub(&p->p_runtime, PCPU_PTR(switchtime)); 489 490 #ifdef DDB 491 /* 492 * Don't perform context switches from the debugger. 493 */ 494 if (db_active) { 495 mtx_unlock_spin(&sched_lock); 496 db_print_backtrace(); 497 db_error("Context switches not allowed in the debugger."); 498 } 499 #endif 500 501 /* 502 * Check if the process exceeds its cpu resource allocation. If 503 * over max, arrange to kill the process in ast(). 504 */ 505 if (p->p_cpulimit != RLIM_INFINITY && 506 p->p_runtime.sec > p->p_cpulimit) { 507 p->p_sflag |= PS_XCPU; 508 td->td_flags |= TDF_ASTPENDING; 509 } 510 511 /* 512 * Finish up stats for outgoing thread. 513 */ 514 cnt.v_swtch++; 515 PCPU_SET(switchtime, new_switchtime); 516 CTR3(KTR_PROC, "mi_switch: old thread %p (pid %d, %s)", td, p->p_pid, 517 p->p_comm); 518 sched_nest = sched_lock.mtx_recurse; 519 if (td->td_proc->p_flag & P_SA) 520 thread_switchout(td); 521 sched_switchout(td); 522 523 #if !defined(__alpha__) && !defined(__powerpc__) 524 newtd = choosethread(); 525 if (td != newtd) 526 cpu_switch(td, newtd); /* SHAZAM!! */ 527 #else 528 cpu_switch(); /* SHAZAM!!*/ 529 #endif 530 531 sched_lock.mtx_recurse = sched_nest; 532 sched_lock.mtx_lock = (uintptr_t)td; 533 sched_switchin(td); 534 535 /* 536 * Start setting up stats etc. for the incoming thread. 537 * Similar code in fork_exit() is returned to by cpu_switch() 538 * in the case of a new thread/process. 539 */ 540 CTR3(KTR_PROC, "mi_switch: new thread %p (pid %d, %s)", td, p->p_pid, 541 p->p_comm); 542 if (PCPU_GET(switchtime.sec) == 0) 543 binuptime(PCPU_PTR(switchtime)); 544 PCPU_SET(switchticks, ticks); 545 546 /* 547 * Call the switchin function while still holding the scheduler lock 548 * (used by the idlezero code and the general page-zeroing code) 549 */ 550 if (td->td_switchin) 551 td->td_switchin(); 552 553 /* 554 * If the last thread was exiting, finish cleaning it up. 555 */ 556 if ((td = PCPU_GET(deadthread))) { 557 PCPU_SET(deadthread, NULL); 558 thread_stash(td); 559 } 560 } 561 562 /* 563 * Change process state to be runnable, 564 * placing it on the run queue if it is in memory, 565 * and awakening the swapper if it isn't in memory. 566 */ 567 void 568 setrunnable(struct thread *td) 569 { 570 struct proc *p = td->td_proc; 571 572 mtx_assert(&sched_lock, MA_OWNED); 573 switch (p->p_state) { 574 case PRS_ZOMBIE: 575 panic("setrunnable(1)"); 576 default: 577 break; 578 } 579 switch (td->td_state) { 580 case TDS_RUNNING: 581 case TDS_RUNQ: 582 return; 583 case TDS_INHIBITED: 584 /* 585 * If we are only inhibited because we are swapped out 586 * then arange to swap in this process. Otherwise just return. 587 */ 588 if (td->td_inhibitors != TDI_SWAPPED) 589 return; 590 /* XXX: intentional fall-through ? */ 591 case TDS_CAN_RUN: 592 break; 593 default: 594 printf("state is 0x%x", td->td_state); 595 panic("setrunnable(2)"); 596 } 597 if ((p->p_sflag & PS_INMEM) == 0) { 598 if ((p->p_sflag & PS_SWAPPINGIN) == 0) { 599 p->p_sflag |= PS_SWAPINREQ; 600 wakeup(&proc0); 601 } 602 } else 603 sched_wakeup(td); 604 } 605 606 /* 607 * Compute a tenex style load average of a quantity on 608 * 1, 5 and 15 minute intervals. 609 * XXXKSE Needs complete rewrite when correct info is available. 610 * Completely Bogus.. only works with 1:1 (but compiles ok now :-) 611 */ 612 static void 613 loadav(void *arg) 614 { 615 int i, nrun; 616 struct loadavg *avg; 617 struct proc *p; 618 struct thread *td; 619 620 avg = &averunnable; 621 sx_slock(&allproc_lock); 622 nrun = 0; 623 FOREACH_PROC_IN_SYSTEM(p) { 624 FOREACH_THREAD_IN_PROC(p, td) { 625 switch (td->td_state) { 626 case TDS_RUNQ: 627 case TDS_RUNNING: 628 if ((p->p_flag & P_NOLOAD) != 0) 629 goto nextproc; 630 nrun++; /* XXXKSE */ 631 default: 632 break; 633 } 634 nextproc: 635 continue; 636 } 637 } 638 sx_sunlock(&allproc_lock); 639 for (i = 0; i < 3; i++) 640 avg->ldavg[i] = (cexp[i] * avg->ldavg[i] + 641 nrun * FSCALE * (FSCALE - cexp[i])) >> FSHIFT; 642 643 /* 644 * Schedule the next update to occur after 5 seconds, but add a 645 * random variation to avoid synchronisation with processes that 646 * run at regular intervals. 647 */ 648 callout_reset(&loadav_callout, hz * 4 + (int)(random() % (hz * 2 + 1)), 649 loadav, NULL); 650 } 651 652 static void 653 lboltcb(void *arg) 654 { 655 wakeup(&lbolt); 656 callout_reset(&lbolt_callout, hz, lboltcb, NULL); 657 } 658 659 /* ARGSUSED */ 660 static void 661 sched_setup(dummy) 662 void *dummy; 663 { 664 callout_init(&loadav_callout, 0); 665 callout_init(&lbolt_callout, 1); 666 667 /* Kick off timeout driven events by calling first time. */ 668 loadav(NULL); 669 lboltcb(NULL); 670 } 671 672 /* 673 * General purpose yield system call 674 */ 675 int 676 yield(struct thread *td, struct yield_args *uap) 677 { 678 struct ksegrp *kg = td->td_ksegrp; 679 680 mtx_assert(&Giant, MA_NOTOWNED); 681 mtx_lock_spin(&sched_lock); 682 kg->kg_proc->p_stats->p_ru.ru_nvcsw++; 683 sched_prio(td, PRI_MAX_TIMESHARE); 684 mi_switch(); 685 mtx_unlock_spin(&sched_lock); 686 td->td_retval[0] = 0; 687 688 return (0); 689 } 690 691