kern_synch.c revision 69376
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 * $FreeBSD: head/sys/kern/kern_synch.c 69376 2000-11-30 00:51:16Z jhb $ 40 */ 41 42#include "opt_ktrace.h" 43 44#include <sys/param.h> 45#include <sys/systm.h> 46#include <sys/proc.h> 47#include <sys/ipl.h> 48#include <sys/kernel.h> 49#include <sys/ktr.h> 50#include <sys/mutex.h> 51#include <sys/signalvar.h> 52#include <sys/resourcevar.h> 53#include <sys/vmmeter.h> 54#include <sys/sysctl.h> 55#include <vm/vm.h> 56#include <vm/vm_extern.h> 57#ifdef KTRACE 58#include <sys/uio.h> 59#include <sys/ktrace.h> 60#endif 61 62#include <machine/cpu.h> 63#include <machine/smp.h> 64 65static void sched_setup __P((void *dummy)); 66SYSINIT(sched_setup, SI_SUB_KICK_SCHEDULER, SI_ORDER_FIRST, sched_setup, NULL) 67 68u_char curpriority; 69int hogticks; 70int lbolt; 71int sched_quantum; /* Roundrobin scheduling quantum in ticks. */ 72 73static struct callout schedcpu_callout; 74static struct callout roundrobin_callout; 75 76static int curpriority_cmp __P((struct proc *p)); 77static void endtsleep __P((void *)); 78static void maybe_resched __P((struct proc *chk)); 79static void roundrobin __P((void *arg)); 80static void schedcpu __P((void *arg)); 81static void updatepri __P((struct proc *p)); 82 83static int 84sysctl_kern_quantum(SYSCTL_HANDLER_ARGS) 85{ 86 int error, new_val; 87 88 new_val = sched_quantum * tick; 89 error = sysctl_handle_int(oidp, &new_val, 0, req); 90 if (error != 0 || req->newptr == NULL) 91 return (error); 92 if (new_val < tick) 93 return (EINVAL); 94 sched_quantum = new_val / tick; 95 hogticks = 2 * sched_quantum; 96 return (0); 97} 98 99SYSCTL_PROC(_kern, OID_AUTO, quantum, CTLTYPE_INT|CTLFLAG_RW, 100 0, sizeof sched_quantum, sysctl_kern_quantum, "I", ""); 101 102/*- 103 * Compare priorities. Return: 104 * <0: priority of p < current priority 105 * 0: priority of p == current priority 106 * >0: priority of p > current priority 107 * The priorities are the normal priorities or the normal realtime priorities 108 * if p is on the same scheduler as curproc. Otherwise the process on the 109 * more realtimeish scheduler has lowest priority. As usual, a higher 110 * priority really means a lower priority. 111 */ 112static int 113curpriority_cmp(p) 114 struct proc *p; 115{ 116 int c_class, p_class; 117 118 c_class = RTP_PRIO_BASE(curproc->p_rtprio.type); 119 p_class = RTP_PRIO_BASE(p->p_rtprio.type); 120 if (p_class != c_class) 121 return (p_class - c_class); 122 if (p_class == RTP_PRIO_NORMAL) 123 return (((int)p->p_priority - (int)curpriority) / PPQ); 124 return ((int)p->p_rtprio.prio - (int)curproc->p_rtprio.prio); 125} 126 127/* 128 * Arrange to reschedule if necessary, taking the priorities and 129 * schedulers into account. 130 */ 131static void 132maybe_resched(chk) 133 struct proc *chk; 134{ 135 struct proc *p = curproc; /* XXX */ 136 137 /* 138 * XXX idle scheduler still broken because proccess stays on idle 139 * scheduler during waits (such as when getting FS locks). If a 140 * standard process becomes runaway cpu-bound, the system can lockup 141 * due to idle-scheduler processes in wakeup never getting any cpu. 142 */ 143 if (p == idleproc) { 144#if 0 145 need_resched(); 146#endif 147 } else if (chk == p) { 148 /* We may need to yield if our priority has been raised. */ 149 if (curpriority_cmp(chk) > 0) 150 need_resched(); 151 } else if (curpriority_cmp(chk) < 0) 152 need_resched(); 153} 154 155int 156roundrobin_interval(void) 157{ 158 return (sched_quantum); 159} 160 161/* 162 * Force switch among equal priority processes every 100ms. 163 */ 164/* ARGSUSED */ 165static void 166roundrobin(arg) 167 void *arg; 168{ 169#ifndef SMP 170 struct proc *p = curproc; /* XXX */ 171#endif 172 173#ifdef SMP 174 need_resched(); 175 forward_roundrobin(); 176#else 177 if (p == idleproc || RTP_PRIO_NEED_RR(p->p_rtprio.type)) 178 need_resched(); 179#endif 180 181 callout_reset(&roundrobin_callout, sched_quantum, roundrobin, NULL); 182} 183 184/* 185 * Constants for digital decay and forget: 186 * 90% of (p_estcpu) usage in 5 * loadav time 187 * 95% of (p_pctcpu) usage in 60 seconds (load insensitive) 188 * Note that, as ps(1) mentions, this can let percentages 189 * total over 100% (I've seen 137.9% for 3 processes). 190 * 191 * Note that schedclock() updates p_estcpu and p_cpticks asynchronously. 192 * 193 * We wish to decay away 90% of p_estcpu in (5 * loadavg) seconds. 194 * That is, the system wants to compute a value of decay such 195 * that the following for loop: 196 * for (i = 0; i < (5 * loadavg); i++) 197 * p_estcpu *= decay; 198 * will compute 199 * p_estcpu *= 0.1; 200 * for all values of loadavg: 201 * 202 * Mathematically this loop can be expressed by saying: 203 * decay ** (5 * loadavg) ~= .1 204 * 205 * The system computes decay as: 206 * decay = (2 * loadavg) / (2 * loadavg + 1) 207 * 208 * We wish to prove that the system's computation of decay 209 * will always fulfill the equation: 210 * decay ** (5 * loadavg) ~= .1 211 * 212 * If we compute b as: 213 * b = 2 * loadavg 214 * then 215 * decay = b / (b + 1) 216 * 217 * We now need to prove two things: 218 * 1) Given factor ** (5 * loadavg) ~= .1, prove factor == b/(b+1) 219 * 2) Given b/(b+1) ** power ~= .1, prove power == (5 * loadavg) 220 * 221 * Facts: 222 * For x close to zero, exp(x) =~ 1 + x, since 223 * exp(x) = 0! + x**1/1! + x**2/2! + ... . 224 * therefore exp(-1/b) =~ 1 - (1/b) = (b-1)/b. 225 * For x close to zero, ln(1+x) =~ x, since 226 * ln(1+x) = x - x**2/2 + x**3/3 - ... -1 < x < 1 227 * therefore ln(b/(b+1)) = ln(1 - 1/(b+1)) =~ -1/(b+1). 228 * ln(.1) =~ -2.30 229 * 230 * Proof of (1): 231 * Solve (factor)**(power) =~ .1 given power (5*loadav): 232 * solving for factor, 233 * ln(factor) =~ (-2.30/5*loadav), or 234 * factor =~ exp(-1/((5/2.30)*loadav)) =~ exp(-1/(2*loadav)) = 235 * exp(-1/b) =~ (b-1)/b =~ b/(b+1). QED 236 * 237 * Proof of (2): 238 * Solve (factor)**(power) =~ .1 given factor == (b/(b+1)): 239 * solving for power, 240 * power*ln(b/(b+1)) =~ -2.30, or 241 * power =~ 2.3 * (b + 1) = 4.6*loadav + 2.3 =~ 5*loadav. QED 242 * 243 * Actual power values for the implemented algorithm are as follows: 244 * loadav: 1 2 3 4 245 * power: 5.68 10.32 14.94 19.55 246 */ 247 248/* calculations for digital decay to forget 90% of usage in 5*loadav sec */ 249#define loadfactor(loadav) (2 * (loadav)) 250#define decay_cpu(loadfac, cpu) (((loadfac) * (cpu)) / ((loadfac) + FSCALE)) 251 252/* decay 95% of `p_pctcpu' in 60 seconds; see CCPU_SHIFT before changing */ 253static fixpt_t ccpu = 0.95122942450071400909 * FSCALE; /* exp(-1/20) */ 254SYSCTL_INT(_kern, OID_AUTO, ccpu, CTLFLAG_RD, &ccpu, 0, ""); 255 256/* kernel uses `FSCALE', userland (SHOULD) use kern.fscale */ 257static int fscale __unused = FSCALE; 258SYSCTL_INT(_kern, OID_AUTO, fscale, CTLFLAG_RD, 0, FSCALE, ""); 259 260/* 261 * If `ccpu' is not equal to `exp(-1/20)' and you still want to use the 262 * faster/more-accurate formula, you'll have to estimate CCPU_SHIFT below 263 * and possibly adjust FSHIFT in "param.h" so that (FSHIFT >= CCPU_SHIFT). 264 * 265 * To estimate CCPU_SHIFT for exp(-1/20), the following formula was used: 266 * 1 - exp(-1/20) ~= 0.0487 ~= 0.0488 == 1 (fixed pt, *11* bits). 267 * 268 * If you don't want to bother with the faster/more-accurate formula, you 269 * can set CCPU_SHIFT to (FSHIFT + 1) which will use a slower/less-accurate 270 * (more general) method of calculating the %age of CPU used by a process. 271 */ 272#define CCPU_SHIFT 11 273 274/* 275 * Recompute process priorities, every hz ticks. 276 */ 277/* ARGSUSED */ 278static void 279schedcpu(arg) 280 void *arg; 281{ 282 register fixpt_t loadfac = loadfactor(averunnable.ldavg[0]); 283 register struct proc *p; 284 register int realstathz, s; 285 286 realstathz = stathz ? stathz : hz; 287 lockmgr(&allproc_lock, LK_SHARED, NULL, CURPROC); 288 LIST_FOREACH(p, &allproc, p_list) { 289 /* 290 * Increment time in/out of memory and sleep time 291 * (if sleeping). We ignore overflow; with 16-bit int's 292 * (remember them?) overflow takes 45 days. 293 if (p->p_stat == SWAIT) 294 continue; 295 */ 296 mtx_enter(&sched_lock, MTX_SPIN); 297 p->p_swtime++; 298 if (p->p_stat == SSLEEP || p->p_stat == SSTOP) 299 p->p_slptime++; 300 p->p_pctcpu = (p->p_pctcpu * ccpu) >> FSHIFT; 301 /* 302 * If the process has slept the entire second, 303 * stop recalculating its priority until it wakes up. 304 */ 305 if (p->p_slptime > 1) { 306 mtx_exit(&sched_lock, MTX_SPIN); 307 continue; 308 } 309 310 /* 311 * prevent state changes and protect run queue 312 */ 313 s = splhigh(); 314 315 /* 316 * p_pctcpu is only for ps. 317 */ 318#if (FSHIFT >= CCPU_SHIFT) 319 p->p_pctcpu += (realstathz == 100)? 320 ((fixpt_t) p->p_cpticks) << (FSHIFT - CCPU_SHIFT): 321 100 * (((fixpt_t) p->p_cpticks) 322 << (FSHIFT - CCPU_SHIFT)) / realstathz; 323#else 324 p->p_pctcpu += ((FSCALE - ccpu) * 325 (p->p_cpticks * FSCALE / realstathz)) >> FSHIFT; 326#endif 327 p->p_cpticks = 0; 328 p->p_estcpu = decay_cpu(loadfac, p->p_estcpu); 329 resetpriority(p); 330 if (p->p_priority >= PUSER) { 331 if ((p != curproc) && 332#ifdef SMP 333 p->p_oncpu == 0xff && /* idle */ 334#endif 335 p->p_stat == SRUN && 336 (p->p_flag & P_INMEM) && 337 (p->p_priority / PPQ) != (p->p_usrpri / PPQ)) { 338 remrunqueue(p); 339 p->p_priority = p->p_usrpri; 340 setrunqueue(p); 341 } else 342 p->p_priority = p->p_usrpri; 343 } 344 mtx_exit(&sched_lock, MTX_SPIN); 345 splx(s); 346 } 347 lockmgr(&allproc_lock, LK_RELEASE, NULL, CURPROC); 348 vmmeter(); 349 wakeup((caddr_t)&lbolt); 350 callout_reset(&schedcpu_callout, hz, schedcpu, NULL); 351} 352 353/* 354 * Recalculate the priority of a process after it has slept for a while. 355 * For all load averages >= 1 and max p_estcpu of 255, sleeping for at 356 * least six times the loadfactor will decay p_estcpu to zero. 357 */ 358static void 359updatepri(p) 360 register struct proc *p; 361{ 362 register unsigned int newcpu = p->p_estcpu; 363 register fixpt_t loadfac = loadfactor(averunnable.ldavg[0]); 364 365 if (p->p_slptime > 5 * loadfac) 366 p->p_estcpu = 0; 367 else { 368 p->p_slptime--; /* the first time was done in schedcpu */ 369 while (newcpu && --p->p_slptime) 370 newcpu = decay_cpu(loadfac, newcpu); 371 p->p_estcpu = newcpu; 372 } 373 resetpriority(p); 374} 375 376/* 377 * We're only looking at 7 bits of the address; everything is 378 * aligned to 4, lots of things are aligned to greater powers 379 * of 2. Shift right by 8, i.e. drop the bottom 256 worth. 380 */ 381#define TABLESIZE 128 382static TAILQ_HEAD(slpquehead, proc) slpque[TABLESIZE]; 383#define LOOKUP(x) (((intptr_t)(x) >> 8) & (TABLESIZE - 1)) 384 385void 386sleepinit(void) 387{ 388 int i; 389 390 sched_quantum = hz/10; 391 hogticks = 2 * sched_quantum; 392 for (i = 0; i < TABLESIZE; i++) 393 TAILQ_INIT(&slpque[i]); 394} 395 396/* 397 * General sleep call. Suspends the current process until a wakeup is 398 * performed on the specified identifier. The process will then be made 399 * runnable with the specified priority. Sleeps at most timo/hz seconds 400 * (0 means no timeout). If pri includes PCATCH flag, signals are checked 401 * before and after sleeping, else signals are not checked. Returns 0 if 402 * awakened, EWOULDBLOCK if the timeout expires. If PCATCH is set and a 403 * signal needs to be delivered, ERESTART is returned if the current system 404 * call should be restarted if possible, and EINTR is returned if the system 405 * call should be interrupted by the signal (return EINTR). 406 * 407 * The mutex argument is exited before the caller is suspended, and 408 * entered before msleep returns. If priority includes the PDROP 409 * flag the mutex is not entered before returning. 410 */ 411int 412msleep(ident, mtx, priority, wmesg, timo) 413 void *ident; 414 struct mtx *mtx; 415 int priority, timo; 416 const char *wmesg; 417{ 418 struct proc *p = curproc; 419 int s, sig, catch = priority & PCATCH; 420 int rval = 0; 421 WITNESS_SAVE_DECL(mtx); 422 423#ifdef KTRACE 424 if (p && KTRPOINT(p, KTR_CSW)) 425 ktrcsw(p->p_tracep, 1, 0); 426#endif 427 WITNESS_SLEEP(0, mtx); 428 mtx_enter(&sched_lock, MTX_SPIN); 429 s = splhigh(); 430 if (cold || panicstr) { 431 /* 432 * After a panic, or during autoconfiguration, 433 * just give interrupts a chance, then just return; 434 * don't run any other procs or panic below, 435 * in case this is the idle process and already asleep. 436 */ 437 if (mtx != NULL && priority & PDROP) 438 mtx_exit(mtx, MTX_DEF | MTX_NOSWITCH); 439 mtx_exit(&sched_lock, MTX_SPIN); 440 splx(s); 441 return (0); 442 } 443 444 DROP_GIANT_NOSWITCH(); 445 446 if (mtx != NULL) { 447 mtx_assert(mtx, MA_OWNED | MA_NOTRECURSED); 448 WITNESS_SAVE(mtx, mtx); 449 mtx_exit(mtx, MTX_DEF | MTX_NOSWITCH); 450 if (priority & PDROP) 451 mtx = NULL; 452 } 453 454 KASSERT(p != NULL, ("msleep1")); 455 KASSERT(ident != NULL && p->p_stat == SRUN, ("msleep")); 456 /* 457 * Process may be sitting on a slpque if asleep() was called, remove 458 * it before re-adding. 459 */ 460 if (p->p_wchan != NULL) 461 unsleep(p); 462 463 p->p_wchan = ident; 464 p->p_wmesg = wmesg; 465 p->p_slptime = 0; 466 p->p_priority = priority & PRIMASK; 467 CTR4(KTR_PROC, "msleep: proc %p (pid %d, %s), schedlock %p", 468 p, p->p_pid, p->p_comm, (void *) sched_lock.mtx_lock); 469 TAILQ_INSERT_TAIL(&slpque[LOOKUP(ident)], p, p_slpq); 470 if (timo) 471 callout_reset(&p->p_slpcallout, timo, endtsleep, p); 472 /* 473 * We put ourselves on the sleep queue and start our timeout 474 * before calling CURSIG, as we could stop there, and a wakeup 475 * or a SIGCONT (or both) could occur while we were stopped. 476 * A SIGCONT would cause us to be marked as SSLEEP 477 * without resuming us, thus we must be ready for sleep 478 * when CURSIG is called. If the wakeup happens while we're 479 * stopped, p->p_wchan will be 0 upon return from CURSIG. 480 */ 481 if (catch) { 482 CTR4(KTR_PROC, 483 "msleep caught: proc %p (pid %d, %s), schedlock %p", 484 p, p->p_pid, p->p_comm, (void *) sched_lock.mtx_lock); 485 p->p_flag |= P_SINTR; 486 mtx_exit(&sched_lock, MTX_SPIN); 487 if ((sig = CURSIG(p))) { 488 mtx_enter(&sched_lock, MTX_SPIN); 489 if (p->p_wchan) 490 unsleep(p); 491 p->p_stat = SRUN; 492 goto resume; 493 } 494 mtx_enter(&sched_lock, MTX_SPIN); 495 if (p->p_wchan == 0) { 496 catch = 0; 497 goto resume; 498 } 499 } else 500 sig = 0; 501 p->p_stat = SSLEEP; 502 p->p_stats->p_ru.ru_nvcsw++; 503 mi_switch(); 504 CTR4(KTR_PROC, 505 "msleep resume: proc %p (pid %d, %s), schedlock %p", 506 p, p->p_pid, p->p_comm, (void *) sched_lock.mtx_lock); 507resume: 508 curpriority = p->p_usrpri; 509 splx(s); 510 p->p_flag &= ~P_SINTR; 511 if (p->p_flag & P_TIMEOUT) { 512 p->p_flag &= ~P_TIMEOUT; 513 if (sig == 0) { 514#ifdef KTRACE 515 if (KTRPOINT(p, KTR_CSW)) 516 ktrcsw(p->p_tracep, 0, 0); 517#endif 518 rval = EWOULDBLOCK; 519 mtx_exit(&sched_lock, MTX_SPIN); 520 goto out; 521 } 522 } else if (timo) 523 callout_stop(&p->p_slpcallout); 524 mtx_exit(&sched_lock, MTX_SPIN); 525 526 if (catch && (sig != 0 || (sig = CURSIG(p)))) { 527#ifdef KTRACE 528 if (KTRPOINT(p, KTR_CSW)) 529 ktrcsw(p->p_tracep, 0, 0); 530#endif 531 if (SIGISMEMBER(p->p_sigacts->ps_sigintr, sig)) 532 rval = EINTR; 533 else 534 rval = ERESTART; 535 goto out; 536 } 537out: 538#ifdef KTRACE 539 if (KTRPOINT(p, KTR_CSW)) 540 ktrcsw(p->p_tracep, 0, 0); 541#endif 542 PICKUP_GIANT(); 543 if (mtx != NULL) { 544 mtx_enter(mtx, MTX_DEF); 545 WITNESS_RESTORE(mtx, mtx); 546 } 547 return (rval); 548} 549 550/* 551 * asleep() - async sleep call. Place process on wait queue and return 552 * immediately without blocking. The process stays runnable until mawait() 553 * is called. If ident is NULL, remove process from wait queue if it is still 554 * on one. 555 * 556 * Only the most recent sleep condition is effective when making successive 557 * calls to asleep() or when calling msleep(). 558 * 559 * The timeout, if any, is not initiated until mawait() is called. The sleep 560 * priority, signal, and timeout is specified in the asleep() call but may be 561 * overriden in the mawait() call. 562 * 563 * <<<<<<<< EXPERIMENTAL, UNTESTED >>>>>>>>>> 564 */ 565 566int 567asleep(void *ident, int priority, const char *wmesg, int timo) 568{ 569 struct proc *p = curproc; 570 int s; 571 572 /* 573 * obtain sched_lock while manipulating sleep structures and slpque. 574 * 575 * Remove preexisting wait condition (if any) and place process 576 * on appropriate slpque, but do not put process to sleep. 577 */ 578 579 s = splhigh(); 580 mtx_enter(&sched_lock, MTX_SPIN); 581 582 if (p->p_wchan != NULL) 583 unsleep(p); 584 585 if (ident) { 586 p->p_wchan = ident; 587 p->p_wmesg = wmesg; 588 p->p_slptime = 0; 589 p->p_asleep.as_priority = priority; 590 p->p_asleep.as_timo = timo; 591 TAILQ_INSERT_TAIL(&slpque[LOOKUP(ident)], p, p_slpq); 592 } 593 594 mtx_exit(&sched_lock, MTX_SPIN); 595 splx(s); 596 597 return(0); 598} 599 600/* 601 * mawait() - wait for async condition to occur. The process blocks until 602 * wakeup() is called on the most recent asleep() address. If wakeup is called 603 * prior to mawait(), mawait() winds up being a NOP. 604 * 605 * If mawait() is called more then once (without an intervening asleep() call), 606 * mawait() is still effectively a NOP but it calls mi_switch() to give other 607 * processes some cpu before returning. The process is left runnable. 608 * 609 * <<<<<<<< EXPERIMENTAL, UNTESTED >>>>>>>>>> 610 */ 611 612int 613mawait(struct mtx *mtx, int priority, int timo) 614{ 615 struct proc *p = curproc; 616 int rval = 0; 617 int s; 618 WITNESS_SAVE_DECL(mtx); 619 620 WITNESS_SLEEP(0, mtx); 621 mtx_enter(&sched_lock, MTX_SPIN); 622 DROP_GIANT_NOSWITCH(); 623 if (mtx != NULL) { 624 mtx_assert(mtx, MA_OWNED | MA_NOTRECURSED); 625 WITNESS_SAVE(mtx, mtx); 626 mtx_exit(mtx, MTX_DEF | MTX_NOSWITCH); 627 if (priority & PDROP) 628 mtx = NULL; 629 } 630 631 s = splhigh(); 632 633 if (p->p_wchan != NULL) { 634 int sig; 635 int catch; 636 637 /* 638 * The call to mawait() can override defaults specified in 639 * the original asleep(). 640 */ 641 if (priority < 0) 642 priority = p->p_asleep.as_priority; 643 if (timo < 0) 644 timo = p->p_asleep.as_timo; 645 646 /* 647 * Install timeout 648 */ 649 650 if (timo) 651 callout_reset(&p->p_slpcallout, timo, endtsleep, p); 652 653 sig = 0; 654 catch = priority & PCATCH; 655 656 if (catch) { 657 p->p_flag |= P_SINTR; 658 mtx_exit(&sched_lock, MTX_SPIN); 659 if ((sig = CURSIG(p))) { 660 mtx_enter(&sched_lock, MTX_SPIN); 661 if (p->p_wchan) 662 unsleep(p); 663 p->p_stat = SRUN; 664 goto resume; 665 } 666 mtx_enter(&sched_lock, MTX_SPIN); 667 if (p->p_wchan == NULL) { 668 catch = 0; 669 goto resume; 670 } 671 } 672 p->p_stat = SSLEEP; 673 p->p_stats->p_ru.ru_nvcsw++; 674 mi_switch(); 675resume: 676 curpriority = p->p_usrpri; 677 678 splx(s); 679 p->p_flag &= ~P_SINTR; 680 if (p->p_flag & P_TIMEOUT) { 681 p->p_flag &= ~P_TIMEOUT; 682 if (sig == 0) { 683#ifdef KTRACE 684 if (KTRPOINT(p, KTR_CSW)) 685 ktrcsw(p->p_tracep, 0, 0); 686#endif 687 rval = EWOULDBLOCK; 688 mtx_exit(&sched_lock, MTX_SPIN); 689 goto out; 690 } 691 } else if (timo) 692 callout_stop(&p->p_slpcallout); 693 mtx_exit(&sched_lock, MTX_SPIN); 694 695 if (catch && (sig != 0 || (sig = CURSIG(p)))) { 696#ifdef KTRACE 697 if (KTRPOINT(p, KTR_CSW)) 698 ktrcsw(p->p_tracep, 0, 0); 699#endif 700 if (SIGISMEMBER(p->p_sigacts->ps_sigintr, sig)) 701 rval = EINTR; 702 else 703 rval = ERESTART; 704 goto out; 705 } 706#ifdef KTRACE 707 if (KTRPOINT(p, KTR_CSW)) 708 ktrcsw(p->p_tracep, 0, 0); 709#endif 710 } else { 711 /* 712 * If as_priority is 0, mawait() has been called without an 713 * intervening asleep(). We are still effectively a NOP, 714 * but we call mi_switch() for safety. 715 */ 716 717 if (p->p_asleep.as_priority == 0) { 718 p->p_stats->p_ru.ru_nvcsw++; 719 mi_switch(); 720 } 721 mtx_exit(&sched_lock, MTX_SPIN); 722 splx(s); 723 } 724 725 /* 726 * clear p_asleep.as_priority as an indication that mawait() has been 727 * called. If mawait() is called again without an intervening asleep(), 728 * mawait() is still effectively a NOP but the above mi_switch() code 729 * is triggered as a safety. 730 */ 731 p->p_asleep.as_priority = 0; 732 733out: 734 PICKUP_GIANT(); 735 if (mtx != NULL) { 736 mtx_enter(mtx, MTX_DEF); 737 WITNESS_RESTORE(mtx, mtx); 738 } 739 return (rval); 740} 741 742/* 743 * Implement timeout for msleep or asleep()/mawait() 744 * 745 * If process hasn't been awakened (wchan non-zero), 746 * set timeout flag and undo the sleep. If proc 747 * is stopped, just unsleep so it will remain stopped. 748 */ 749static void 750endtsleep(arg) 751 void *arg; 752{ 753 register struct proc *p; 754 int s; 755 756 p = (struct proc *)arg; 757 CTR4(KTR_PROC, 758 "endtsleep: proc %p (pid %d, %s), schedlock %p", 759 p, p->p_pid, p->p_comm, (void *) sched_lock.mtx_lock); 760 s = splhigh(); 761 mtx_enter(&sched_lock, MTX_SPIN); 762 if (p->p_wchan) { 763 if (p->p_stat == SSLEEP) 764 setrunnable(p); 765 else 766 unsleep(p); 767 p->p_flag |= P_TIMEOUT; 768 } 769 mtx_exit(&sched_lock, MTX_SPIN); 770 splx(s); 771} 772 773/* 774 * Remove a process from its wait queue 775 */ 776void 777unsleep(p) 778 register struct proc *p; 779{ 780 int s; 781 782 s = splhigh(); 783 mtx_enter(&sched_lock, MTX_SPIN); 784 if (p->p_wchan) { 785 TAILQ_REMOVE(&slpque[LOOKUP(p->p_wchan)], p, p_slpq); 786 p->p_wchan = 0; 787 } 788 mtx_exit(&sched_lock, MTX_SPIN); 789 splx(s); 790} 791 792/* 793 * Make all processes sleeping on the specified identifier runnable. 794 */ 795void 796wakeup(ident) 797 register void *ident; 798{ 799 register struct slpquehead *qp; 800 register struct proc *p; 801 int s; 802 803 s = splhigh(); 804 mtx_enter(&sched_lock, MTX_SPIN); 805 qp = &slpque[LOOKUP(ident)]; 806restart: 807 TAILQ_FOREACH(p, qp, p_slpq) { 808 if (p->p_wchan == ident) { 809 TAILQ_REMOVE(qp, p, p_slpq); 810 p->p_wchan = 0; 811 if (p->p_stat == SSLEEP) { 812 /* OPTIMIZED EXPANSION OF setrunnable(p); */ 813 CTR4(KTR_PROC, 814 "wakeup: proc %p (pid %d, %s), schedlock %p", 815 p, p->p_pid, p->p_comm, (void *) sched_lock.mtx_lock); 816 if (p->p_slptime > 1) 817 updatepri(p); 818 p->p_slptime = 0; 819 p->p_stat = SRUN; 820 if (p->p_flag & P_INMEM) { 821 setrunqueue(p); 822 maybe_resched(p); 823 } else { 824 p->p_flag |= P_SWAPINREQ; 825 wakeup((caddr_t)&proc0); 826 } 827 /* END INLINE EXPANSION */ 828 goto restart; 829 } 830 } 831 } 832 mtx_exit(&sched_lock, MTX_SPIN); 833 splx(s); 834} 835 836/* 837 * Make a process sleeping on the specified identifier runnable. 838 * May wake more than one process if a target process is currently 839 * swapped out. 840 */ 841void 842wakeup_one(ident) 843 register void *ident; 844{ 845 register struct slpquehead *qp; 846 register struct proc *p; 847 int s; 848 849 s = splhigh(); 850 mtx_enter(&sched_lock, MTX_SPIN); 851 qp = &slpque[LOOKUP(ident)]; 852 853 TAILQ_FOREACH(p, qp, p_slpq) { 854 if (p->p_wchan == ident) { 855 TAILQ_REMOVE(qp, p, p_slpq); 856 p->p_wchan = 0; 857 if (p->p_stat == SSLEEP) { 858 /* OPTIMIZED EXPANSION OF setrunnable(p); */ 859 CTR4(KTR_PROC, 860 "wakeup1: proc %p (pid %d, %s), schedlock %p", 861 p, p->p_pid, p->p_comm, (void *) sched_lock.mtx_lock); 862 if (p->p_slptime > 1) 863 updatepri(p); 864 p->p_slptime = 0; 865 p->p_stat = SRUN; 866 if (p->p_flag & P_INMEM) { 867 setrunqueue(p); 868 maybe_resched(p); 869 break; 870 } else { 871 p->p_flag |= P_SWAPINREQ; 872 wakeup((caddr_t)&proc0); 873 } 874 /* END INLINE EXPANSION */ 875 } 876 } 877 } 878 mtx_exit(&sched_lock, MTX_SPIN); 879 splx(s); 880} 881 882/* 883 * The machine independent parts of mi_switch(). 884 * Must be called at splstatclock() or higher. 885 */ 886void 887mi_switch() 888{ 889 struct timeval new_switchtime; 890 register struct proc *p = curproc; /* XXX */ 891 register struct rlimit *rlim; 892 int x; 893 894 /* 895 * XXX this spl is almost unnecessary. It is partly to allow for 896 * sloppy callers that don't do it (issignal() via CURSIG() is the 897 * main offender). It is partly to work around a bug in the i386 898 * cpu_switch() (the ipl is not preserved). We ran for years 899 * without it. I think there was only a interrupt latency problem. 900 * The main caller, msleep(), does an splx() a couple of instructions 901 * after calling here. The buggy caller, issignal(), usually calls 902 * here at spl0() and sometimes returns at splhigh(). The process 903 * then runs for a little too long at splhigh(). The ipl gets fixed 904 * when the process returns to user mode (or earlier). 905 * 906 * It would probably be better to always call here at spl0(). Callers 907 * are prepared to give up control to another process, so they must 908 * be prepared to be interrupted. The clock stuff here may not 909 * actually need splstatclock(). 910 */ 911 x = splstatclock(); 912 913 mtx_assert(&sched_lock, MA_OWNED); 914 915#ifdef SIMPLELOCK_DEBUG 916 if (p->p_simple_locks) 917 printf("sleep: holding simple lock\n"); 918#endif 919 /* 920 * Compute the amount of time during which the current 921 * process was running, and add that to its total so far. 922 */ 923 microuptime(&new_switchtime); 924 if (timevalcmp(&new_switchtime, &switchtime, <)) { 925 printf("microuptime() went backwards (%ld.%06ld -> %ld.%06ld)\n", 926 switchtime.tv_sec, switchtime.tv_usec, 927 new_switchtime.tv_sec, new_switchtime.tv_usec); 928 new_switchtime = switchtime; 929 } else { 930 p->p_runtime += (new_switchtime.tv_usec - switchtime.tv_usec) + 931 (new_switchtime.tv_sec - switchtime.tv_sec) * (int64_t)1000000; 932 } 933 934 /* 935 * Check if the process exceeds its cpu resource allocation. 936 * If over max, kill it. 937 * 938 * XXX drop sched_lock, pickup Giant 939 */ 940 if (p->p_stat != SZOMB && p->p_limit->p_cpulimit != RLIM_INFINITY && 941 p->p_runtime > p->p_limit->p_cpulimit) { 942 rlim = &p->p_rlimit[RLIMIT_CPU]; 943 if (p->p_runtime / (rlim_t)1000000 >= rlim->rlim_max) { 944 killproc(p, "exceeded maximum CPU limit"); 945 } else { 946 psignal(p, SIGXCPU); 947 if (rlim->rlim_cur < rlim->rlim_max) { 948 /* XXX: we should make a private copy */ 949 rlim->rlim_cur += 5; 950 } 951 } 952 } 953 954 /* 955 * Pick a new current process and record its start time. 956 */ 957 cnt.v_swtch++; 958 switchtime = new_switchtime; 959 CTR4(KTR_PROC, "mi_switch: old proc %p (pid %d, %s), schedlock %p", 960 p, p->p_pid, p->p_comm, (void *) sched_lock.mtx_lock); 961 cpu_switch(); 962 CTR4(KTR_PROC, "mi_switch: new proc %p (pid %d, %s), schedlock %p", 963 p, p->p_pid, p->p_comm, (void *) sched_lock.mtx_lock); 964 if (switchtime.tv_sec == 0) 965 microuptime(&switchtime); 966 switchticks = ticks; 967 splx(x); 968} 969 970/* 971 * Change process state to be runnable, 972 * placing it on the run queue if it is in memory, 973 * and awakening the swapper if it isn't in memory. 974 */ 975void 976setrunnable(p) 977 register struct proc *p; 978{ 979 register int s; 980 981 s = splhigh(); 982 mtx_enter(&sched_lock, MTX_SPIN); 983 switch (p->p_stat) { 984 case 0: 985 case SRUN: 986 case SZOMB: 987 case SWAIT: 988 default: 989 panic("setrunnable"); 990 case SSTOP: 991 case SSLEEP: 992 unsleep(p); /* e.g. when sending signals */ 993 break; 994 995 case SIDL: 996 break; 997 } 998 p->p_stat = SRUN; 999 if (p->p_flag & P_INMEM) 1000 setrunqueue(p); 1001 splx(s); 1002 if (p->p_slptime > 1) 1003 updatepri(p); 1004 p->p_slptime = 0; 1005 if ((p->p_flag & P_INMEM) == 0) { 1006 p->p_flag |= P_SWAPINREQ; 1007 wakeup((caddr_t)&proc0); 1008 } 1009 else 1010 maybe_resched(p); 1011 mtx_exit(&sched_lock, MTX_SPIN); 1012} 1013 1014/* 1015 * Compute the priority of a process when running in user mode. 1016 * Arrange to reschedule if the resulting priority is better 1017 * than that of the current process. 1018 */ 1019void 1020resetpriority(p) 1021 register struct proc *p; 1022{ 1023 register unsigned int newpriority; 1024 1025 mtx_enter(&sched_lock, MTX_SPIN); 1026 if (p->p_rtprio.type == RTP_PRIO_NORMAL) { 1027 newpriority = PUSER + p->p_estcpu / INVERSE_ESTCPU_WEIGHT + 1028 NICE_WEIGHT * (p->p_nice - PRIO_MIN); 1029 newpriority = min(newpriority, MAXPRI); 1030 p->p_usrpri = newpriority; 1031 } 1032 maybe_resched(p); 1033 mtx_exit(&sched_lock, MTX_SPIN); 1034} 1035 1036/* ARGSUSED */ 1037static void 1038sched_setup(dummy) 1039 void *dummy; 1040{ 1041 1042 callout_init(&schedcpu_callout, 1); 1043 callout_init(&roundrobin_callout, 0); 1044 1045 /* Kick off timeout driven events by calling first time. */ 1046 roundrobin(NULL); 1047 schedcpu(NULL); 1048} 1049 1050/* 1051 * We adjust the priority of the current process. The priority of 1052 * a process gets worse as it accumulates CPU time. The cpu usage 1053 * estimator (p_estcpu) is increased here. resetpriority() will 1054 * compute a different priority each time p_estcpu increases by 1055 * INVERSE_ESTCPU_WEIGHT 1056 * (until MAXPRI is reached). The cpu usage estimator ramps up 1057 * quite quickly when the process is running (linearly), and decays 1058 * away exponentially, at a rate which is proportionally slower when 1059 * the system is busy. The basic principle is that the system will 1060 * 90% forget that the process used a lot of CPU time in 5 * loadav 1061 * seconds. This causes the system to favor processes which haven't 1062 * run much recently, and to round-robin among other processes. 1063 */ 1064void 1065schedclock(p) 1066 struct proc *p; 1067{ 1068 1069 p->p_cpticks++; 1070 p->p_estcpu = ESTCPULIM(p->p_estcpu + 1); 1071 if ((p->p_estcpu % INVERSE_ESTCPU_WEIGHT) == 0) { 1072 resetpriority(p); 1073 if (p->p_priority >= PUSER) 1074 p->p_priority = p->p_usrpri; 1075 } 1076} 1077