kern_synch.c revision 77059
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 77059 2001-05-23 19:38:26Z jhb $ 40 */ 41 42#include "opt_ktrace.h" 43 44#include <sys/param.h> 45#include <sys/systm.h> 46#include <sys/condvar.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/signalvar.h> 54#include <sys/smp.h> 55#include <sys/sx.h> 56#include <sys/sysctl.h> 57#include <sys/sysproto.h> 58#include <sys/vmmeter.h> 59#include <vm/vm.h> 60#include <vm/vm_extern.h> 61#ifdef KTRACE 62#include <sys/uio.h> 63#include <sys/ktrace.h> 64#endif 65 66#include <machine/cpu.h> 67 68static void sched_setup __P((void *dummy)); 69SYSINIT(sched_setup, SI_SUB_KICK_SCHEDULER, SI_ORDER_FIRST, sched_setup, NULL) 70 71int hogticks; 72int lbolt; 73int sched_quantum; /* Roundrobin scheduling quantum in ticks. */ 74 75static struct callout schedcpu_callout; 76static struct callout roundrobin_callout; 77 78static void endtsleep __P((void *)); 79static void roundrobin __P((void *arg)); 80static void schedcpu __P((void *arg)); 81 82static int 83sysctl_kern_quantum(SYSCTL_HANDLER_ARGS) 84{ 85 int error, new_val; 86 87 new_val = sched_quantum * tick; 88 error = sysctl_handle_int(oidp, &new_val, 0, req); 89 if (error != 0 || req->newptr == NULL) 90 return (error); 91 if (new_val < tick) 92 return (EINVAL); 93 sched_quantum = new_val / tick; 94 hogticks = 2 * sched_quantum; 95 return (0); 96} 97 98SYSCTL_PROC(_kern, OID_AUTO, quantum, CTLTYPE_INT|CTLFLAG_RW, 99 0, sizeof sched_quantum, sysctl_kern_quantum, "I", ""); 100 101/* 102 * Arrange to reschedule if necessary, taking the priorities and 103 * schedulers into account. 104 */ 105void 106maybe_resched(p) 107 struct proc *p; 108{ 109 110 mtx_assert(&sched_lock, MA_OWNED); 111 if (p->p_pri.pri_level < curproc->p_pri.pri_level) 112 need_resched(curproc); 113} 114 115int 116roundrobin_interval(void) 117{ 118 return (sched_quantum); 119} 120 121/* 122 * Force switch among equal priority processes every 100ms. 123 */ 124/* ARGSUSED */ 125static void 126roundrobin(arg) 127 void *arg; 128{ 129 130 mtx_lock_spin(&sched_lock); 131 need_resched(curproc); 132#ifdef SMP 133 forward_roundrobin(); 134#endif 135 mtx_unlock_spin(&sched_lock); 136 137 callout_reset(&roundrobin_callout, sched_quantum, roundrobin, NULL); 138} 139 140/* 141 * Constants for digital decay and forget: 142 * 90% of (p_estcpu) usage in 5 * loadav time 143 * 95% of (p_pctcpu) usage in 60 seconds (load insensitive) 144 * Note that, as ps(1) mentions, this can let percentages 145 * total over 100% (I've seen 137.9% for 3 processes). 146 * 147 * Note that schedclock() updates p_estcpu and p_cpticks asynchronously. 148 * 149 * We wish to decay away 90% of p_estcpu in (5 * loadavg) seconds. 150 * That is, the system wants to compute a value of decay such 151 * that the following for loop: 152 * for (i = 0; i < (5 * loadavg); i++) 153 * p_estcpu *= decay; 154 * will compute 155 * p_estcpu *= 0.1; 156 * for all values of loadavg: 157 * 158 * Mathematically this loop can be expressed by saying: 159 * decay ** (5 * loadavg) ~= .1 160 * 161 * The system computes decay as: 162 * decay = (2 * loadavg) / (2 * loadavg + 1) 163 * 164 * We wish to prove that the system's computation of decay 165 * will always fulfill the equation: 166 * decay ** (5 * loadavg) ~= .1 167 * 168 * If we compute b as: 169 * b = 2 * loadavg 170 * then 171 * decay = b / (b + 1) 172 * 173 * We now need to prove two things: 174 * 1) Given factor ** (5 * loadavg) ~= .1, prove factor == b/(b+1) 175 * 2) Given b/(b+1) ** power ~= .1, prove power == (5 * loadavg) 176 * 177 * Facts: 178 * For x close to zero, exp(x) =~ 1 + x, since 179 * exp(x) = 0! + x**1/1! + x**2/2! + ... . 180 * therefore exp(-1/b) =~ 1 - (1/b) = (b-1)/b. 181 * For x close to zero, ln(1+x) =~ x, since 182 * ln(1+x) = x - x**2/2 + x**3/3 - ... -1 < x < 1 183 * therefore ln(b/(b+1)) = ln(1 - 1/(b+1)) =~ -1/(b+1). 184 * ln(.1) =~ -2.30 185 * 186 * Proof of (1): 187 * Solve (factor)**(power) =~ .1 given power (5*loadav): 188 * solving for factor, 189 * ln(factor) =~ (-2.30/5*loadav), or 190 * factor =~ exp(-1/((5/2.30)*loadav)) =~ exp(-1/(2*loadav)) = 191 * exp(-1/b) =~ (b-1)/b =~ b/(b+1). QED 192 * 193 * Proof of (2): 194 * Solve (factor)**(power) =~ .1 given factor == (b/(b+1)): 195 * solving for power, 196 * power*ln(b/(b+1)) =~ -2.30, or 197 * power =~ 2.3 * (b + 1) = 4.6*loadav + 2.3 =~ 5*loadav. QED 198 * 199 * Actual power values for the implemented algorithm are as follows: 200 * loadav: 1 2 3 4 201 * power: 5.68 10.32 14.94 19.55 202 */ 203 204/* calculations for digital decay to forget 90% of usage in 5*loadav sec */ 205#define loadfactor(loadav) (2 * (loadav)) 206#define decay_cpu(loadfac, cpu) (((loadfac) * (cpu)) / ((loadfac) + FSCALE)) 207 208/* decay 95% of `p_pctcpu' in 60 seconds; see CCPU_SHIFT before changing */ 209static fixpt_t ccpu = 0.95122942450071400909 * FSCALE; /* exp(-1/20) */ 210SYSCTL_INT(_kern, OID_AUTO, ccpu, CTLFLAG_RD, &ccpu, 0, ""); 211 212/* kernel uses `FSCALE', userland (SHOULD) use kern.fscale */ 213static int fscale __unused = FSCALE; 214SYSCTL_INT(_kern, OID_AUTO, fscale, CTLFLAG_RD, 0, FSCALE, ""); 215 216/* 217 * If `ccpu' is not equal to `exp(-1/20)' and you still want to use the 218 * faster/more-accurate formula, you'll have to estimate CCPU_SHIFT below 219 * and possibly adjust FSHIFT in "param.h" so that (FSHIFT >= CCPU_SHIFT). 220 * 221 * To estimate CCPU_SHIFT for exp(-1/20), the following formula was used: 222 * 1 - exp(-1/20) ~= 0.0487 ~= 0.0488 == 1 (fixed pt, *11* bits). 223 * 224 * If you don't want to bother with the faster/more-accurate formula, you 225 * can set CCPU_SHIFT to (FSHIFT + 1) which will use a slower/less-accurate 226 * (more general) method of calculating the %age of CPU used by a process. 227 */ 228#define CCPU_SHIFT 11 229 230/* 231 * Recompute process priorities, every hz ticks. 232 * MP-safe, called without the Giant mutex. 233 */ 234/* ARGSUSED */ 235static void 236schedcpu(arg) 237 void *arg; 238{ 239 register fixpt_t loadfac = loadfactor(averunnable.ldavg[0]); 240 register struct proc *p; 241 register int realstathz, s; 242 243 realstathz = stathz ? stathz : hz; 244 sx_slock(&allproc_lock); 245 LIST_FOREACH(p, &allproc, p_list) { 246 /* 247 * Increment time in/out of memory and sleep time 248 * (if sleeping). We ignore overflow; with 16-bit int's 249 * (remember them?) overflow takes 45 days. 250 if (p->p_stat == SWAIT) 251 continue; 252 */ 253 mtx_lock_spin(&sched_lock); 254 p->p_swtime++; 255 if (p->p_stat == SSLEEP || p->p_stat == SSTOP) 256 p->p_slptime++; 257 p->p_pctcpu = (p->p_pctcpu * ccpu) >> FSHIFT; 258 /* 259 * If the process has slept the entire second, 260 * stop recalculating its priority until it wakes up. 261 */ 262 if (p->p_slptime > 1) { 263 mtx_unlock_spin(&sched_lock); 264 continue; 265 } 266 267 /* 268 * prevent state changes and protect run queue 269 */ 270 s = splhigh(); 271 272 /* 273 * p_pctcpu is only for ps. 274 */ 275#if (FSHIFT >= CCPU_SHIFT) 276 p->p_pctcpu += (realstathz == 100)? 277 ((fixpt_t) p->p_cpticks) << (FSHIFT - CCPU_SHIFT): 278 100 * (((fixpt_t) p->p_cpticks) 279 << (FSHIFT - CCPU_SHIFT)) / realstathz; 280#else 281 p->p_pctcpu += ((FSCALE - ccpu) * 282 (p->p_cpticks * FSCALE / realstathz)) >> FSHIFT; 283#endif 284 p->p_cpticks = 0; 285 p->p_estcpu = decay_cpu(loadfac, p->p_estcpu); 286 resetpriority(p); 287 if (p->p_pri.pri_level >= PUSER) { 288 if ((p != curproc) && 289#ifdef SMP 290 p->p_oncpu == NOCPU && /* idle */ 291#endif 292 p->p_stat == SRUN && 293 (p->p_sflag & PS_INMEM) && 294 (p->p_pri.pri_level / RQ_PPQ) != 295 (p->p_pri.pri_user / RQ_PPQ)) { 296 remrunqueue(p); 297 p->p_pri.pri_level = p->p_pri.pri_user; 298 setrunqueue(p); 299 } else 300 p->p_pri.pri_level = p->p_pri.pri_user; 301 } 302 mtx_unlock_spin(&sched_lock); 303 splx(s); 304 } 305 sx_sunlock(&allproc_lock); 306 vmmeter(); 307 wakeup((caddr_t)&lbolt); 308 callout_reset(&schedcpu_callout, hz, schedcpu, NULL); 309} 310 311/* 312 * Recalculate the priority of a process after it has slept for a while. 313 * For all load averages >= 1 and max p_estcpu of 255, sleeping for at 314 * least six times the loadfactor will decay p_estcpu to zero. 315 */ 316void 317updatepri(p) 318 register struct proc *p; 319{ 320 register unsigned int newcpu = p->p_estcpu; 321 register fixpt_t loadfac = loadfactor(averunnable.ldavg[0]); 322 323 if (p->p_slptime > 5 * loadfac) 324 p->p_estcpu = 0; 325 else { 326 p->p_slptime--; /* the first time was done in schedcpu */ 327 while (newcpu && --p->p_slptime) 328 newcpu = decay_cpu(loadfac, newcpu); 329 p->p_estcpu = newcpu; 330 } 331 resetpriority(p); 332} 333 334/* 335 * We're only looking at 7 bits of the address; everything is 336 * aligned to 4, lots of things are aligned to greater powers 337 * of 2. Shift right by 8, i.e. drop the bottom 256 worth. 338 */ 339#define TABLESIZE 128 340static TAILQ_HEAD(slpquehead, proc) slpque[TABLESIZE]; 341#define LOOKUP(x) (((intptr_t)(x) >> 8) & (TABLESIZE - 1)) 342 343void 344sleepinit(void) 345{ 346 int i; 347 348 sched_quantum = hz/10; 349 hogticks = 2 * sched_quantum; 350 for (i = 0; i < TABLESIZE; i++) 351 TAILQ_INIT(&slpque[i]); 352} 353 354/* 355 * General sleep call. Suspends the current process until a wakeup is 356 * performed on the specified identifier. The process will then be made 357 * runnable with the specified priority. Sleeps at most timo/hz seconds 358 * (0 means no timeout). If pri includes PCATCH flag, signals are checked 359 * before and after sleeping, else signals are not checked. Returns 0 if 360 * awakened, EWOULDBLOCK if the timeout expires. If PCATCH is set and a 361 * signal needs to be delivered, ERESTART is returned if the current system 362 * call should be restarted if possible, and EINTR is returned if the system 363 * call should be interrupted by the signal (return EINTR). 364 * 365 * The mutex argument is exited before the caller is suspended, and 366 * entered before msleep returns. If priority includes the PDROP 367 * flag the mutex is not entered before returning. 368 */ 369int 370msleep(ident, mtx, priority, wmesg, timo) 371 void *ident; 372 struct mtx *mtx; 373 int priority, timo; 374 const char *wmesg; 375{ 376 struct proc *p = curproc; 377 int sig, catch = priority & PCATCH; 378 int rval = 0; 379 WITNESS_SAVE_DECL(mtx); 380 381#ifdef KTRACE 382 if (p && KTRPOINT(p, KTR_CSW)) 383 ktrcsw(p->p_tracep, 1, 0); 384#endif 385 WITNESS_SLEEP(0, &mtx->mtx_object); 386 KASSERT(timo != 0 || mtx_owned(&Giant) || mtx != NULL, 387 ("sleeping without a mutex")); 388 mtx_lock_spin(&sched_lock); 389 if (cold || panicstr) { 390 /* 391 * After a panic, or during autoconfiguration, 392 * just give interrupts a chance, then just return; 393 * don't run any other procs or panic below, 394 * in case this is the idle process and already asleep. 395 */ 396 if (mtx != NULL && priority & PDROP) 397 mtx_unlock_flags(mtx, MTX_NOSWITCH); 398 mtx_unlock_spin(&sched_lock); 399 return (0); 400 } 401 402 DROP_GIANT_NOSWITCH(); 403 404 if (mtx != NULL) { 405 mtx_assert(mtx, MA_OWNED | MA_NOTRECURSED); 406 WITNESS_SAVE(&mtx->mtx_object, mtx); 407 mtx_unlock_flags(mtx, MTX_NOSWITCH); 408 if (priority & PDROP) 409 mtx = NULL; 410 } 411 412 KASSERT(p != NULL, ("msleep1")); 413 KASSERT(ident != NULL && p->p_stat == SRUN, ("msleep")); 414 /* 415 * Process may be sitting on a slpque if asleep() was called, remove 416 * it before re-adding. 417 */ 418 if (p->p_wchan != NULL) 419 unsleep(p); 420 421 p->p_wchan = ident; 422 p->p_wmesg = wmesg; 423 p->p_slptime = 0; 424 p->p_pri.pri_level = priority & PRIMASK; 425 CTR4(KTR_PROC, "msleep: proc %p (pid %d, %s), schedlock %p", 426 p, p->p_pid, p->p_comm, (void *) sched_lock.mtx_lock); 427 TAILQ_INSERT_TAIL(&slpque[LOOKUP(ident)], p, p_slpq); 428 if (timo) 429 callout_reset(&p->p_slpcallout, timo, endtsleep, p); 430 /* 431 * We put ourselves on the sleep queue and start our timeout 432 * before calling CURSIG, as we could stop there, and a wakeup 433 * or a SIGCONT (or both) could occur while we were stopped. 434 * A SIGCONT would cause us to be marked as SSLEEP 435 * without resuming us, thus we must be ready for sleep 436 * when CURSIG is called. If the wakeup happens while we're 437 * stopped, p->p_wchan will be 0 upon return from CURSIG. 438 */ 439 if (catch) { 440 CTR4(KTR_PROC, 441 "msleep caught: proc %p (pid %d, %s), schedlock %p", 442 p, p->p_pid, p->p_comm, (void *) sched_lock.mtx_lock); 443 p->p_sflag |= PS_SINTR; 444 mtx_unlock_spin(&sched_lock); 445 if ((sig = CURSIG(p))) { 446 mtx_lock_spin(&sched_lock); 447 if (p->p_wchan) 448 unsleep(p); 449 p->p_stat = SRUN; 450 goto resume; 451 } 452 mtx_lock_spin(&sched_lock); 453 if (p->p_wchan == NULL) { 454 catch = 0; 455 goto resume; 456 } 457 } else 458 sig = 0; 459 p->p_stat = SSLEEP; 460 p->p_stats->p_ru.ru_nvcsw++; 461 mi_switch(); 462 CTR4(KTR_PROC, 463 "msleep resume: proc %p (pid %d, %s), schedlock %p", 464 p, p->p_pid, p->p_comm, (void *) sched_lock.mtx_lock); 465resume: 466 p->p_sflag &= ~PS_SINTR; 467 if (p->p_sflag & PS_TIMEOUT) { 468 p->p_sflag &= ~PS_TIMEOUT; 469 if (sig == 0) { 470#ifdef KTRACE 471 if (KTRPOINT(p, KTR_CSW)) 472 ktrcsw(p->p_tracep, 0, 0); 473#endif 474 rval = EWOULDBLOCK; 475 mtx_unlock_spin(&sched_lock); 476 goto out; 477 } 478 } else if (timo) 479 callout_stop(&p->p_slpcallout); 480 mtx_unlock_spin(&sched_lock); 481 482 if (catch && (sig != 0 || (sig = CURSIG(p)))) { 483#ifdef KTRACE 484 if (KTRPOINT(p, KTR_CSW)) 485 ktrcsw(p->p_tracep, 0, 0); 486#endif 487 PROC_LOCK(p); 488 if (SIGISMEMBER(p->p_sigacts->ps_sigintr, sig)) 489 rval = EINTR; 490 else 491 rval = ERESTART; 492 PROC_UNLOCK(p); 493 goto out; 494 } 495out: 496#ifdef KTRACE 497 if (KTRPOINT(p, KTR_CSW)) 498 ktrcsw(p->p_tracep, 0, 0); 499#endif 500 PICKUP_GIANT(); 501 if (mtx != NULL) { 502 mtx_lock(mtx); 503 WITNESS_RESTORE(&mtx->mtx_object, mtx); 504 } 505 return (rval); 506} 507 508/* 509 * asleep() - async sleep call. Place process on wait queue and return 510 * immediately without blocking. The process stays runnable until mawait() 511 * is called. If ident is NULL, remove process from wait queue if it is still 512 * on one. 513 * 514 * Only the most recent sleep condition is effective when making successive 515 * calls to asleep() or when calling msleep(). 516 * 517 * The timeout, if any, is not initiated until mawait() is called. The sleep 518 * priority, signal, and timeout is specified in the asleep() call but may be 519 * overriden in the mawait() call. 520 * 521 * <<<<<<<< EXPERIMENTAL, UNTESTED >>>>>>>>>> 522 */ 523 524int 525asleep(void *ident, int priority, const char *wmesg, int timo) 526{ 527 struct proc *p = curproc; 528 int s; 529 530 /* 531 * obtain sched_lock while manipulating sleep structures and slpque. 532 * 533 * Remove preexisting wait condition (if any) and place process 534 * on appropriate slpque, but do not put process to sleep. 535 */ 536 537 s = splhigh(); 538 mtx_lock_spin(&sched_lock); 539 540 if (p->p_wchan != NULL) 541 unsleep(p); 542 543 if (ident) { 544 p->p_wchan = ident; 545 p->p_wmesg = wmesg; 546 p->p_slptime = 0; 547 p->p_asleep.as_priority = priority; 548 p->p_asleep.as_timo = timo; 549 TAILQ_INSERT_TAIL(&slpque[LOOKUP(ident)], p, p_slpq); 550 } 551 552 mtx_unlock_spin(&sched_lock); 553 splx(s); 554 555 return(0); 556} 557 558/* 559 * mawait() - wait for async condition to occur. The process blocks until 560 * wakeup() is called on the most recent asleep() address. If wakeup is called 561 * prior to mawait(), mawait() winds up being a NOP. 562 * 563 * If mawait() is called more then once (without an intervening asleep() call), 564 * mawait() is still effectively a NOP but it calls mi_switch() to give other 565 * processes some cpu before returning. The process is left runnable. 566 * 567 * <<<<<<<< EXPERIMENTAL, UNTESTED >>>>>>>>>> 568 */ 569 570int 571mawait(struct mtx *mtx, int priority, int timo) 572{ 573 struct proc *p = curproc; 574 int rval = 0; 575 int s; 576 WITNESS_SAVE_DECL(mtx); 577 578 WITNESS_SLEEP(0, &mtx->mtx_object); 579 KASSERT(timo > 0 || mtx_owned(&Giant) || mtx != NULL, 580 ("sleeping without a mutex")); 581 mtx_lock_spin(&sched_lock); 582 DROP_GIANT_NOSWITCH(); 583 if (mtx != NULL) { 584 mtx_assert(mtx, MA_OWNED | MA_NOTRECURSED); 585 WITNESS_SAVE(&mtx->mtx_object, mtx); 586 mtx_unlock_flags(mtx, MTX_NOSWITCH); 587 if (priority & PDROP) 588 mtx = NULL; 589 } 590 591 s = splhigh(); 592 593 if (p->p_wchan != NULL) { 594 int sig; 595 int catch; 596 597 /* 598 * The call to mawait() can override defaults specified in 599 * the original asleep(). 600 */ 601 if (priority < 0) 602 priority = p->p_asleep.as_priority; 603 if (timo < 0) 604 timo = p->p_asleep.as_timo; 605 606 /* 607 * Install timeout 608 */ 609 610 if (timo) 611 callout_reset(&p->p_slpcallout, timo, endtsleep, p); 612 613 sig = 0; 614 catch = priority & PCATCH; 615 616 if (catch) { 617 p->p_sflag |= PS_SINTR; 618 mtx_unlock_spin(&sched_lock); 619 if ((sig = CURSIG(p))) { 620 mtx_lock_spin(&sched_lock); 621 if (p->p_wchan) 622 unsleep(p); 623 p->p_stat = SRUN; 624 goto resume; 625 } 626 mtx_lock_spin(&sched_lock); 627 if (p->p_wchan == NULL) { 628 catch = 0; 629 goto resume; 630 } 631 } 632 p->p_stat = SSLEEP; 633 p->p_stats->p_ru.ru_nvcsw++; 634 mi_switch(); 635resume: 636 637 splx(s); 638 p->p_sflag &= ~PS_SINTR; 639 if (p->p_sflag & PS_TIMEOUT) { 640 p->p_sflag &= ~PS_TIMEOUT; 641 if (sig == 0) { 642#ifdef KTRACE 643 if (KTRPOINT(p, KTR_CSW)) 644 ktrcsw(p->p_tracep, 0, 0); 645#endif 646 rval = EWOULDBLOCK; 647 mtx_unlock_spin(&sched_lock); 648 goto out; 649 } 650 } else if (timo) 651 callout_stop(&p->p_slpcallout); 652 mtx_unlock_spin(&sched_lock); 653 654 if (catch && (sig != 0 || (sig = CURSIG(p)))) { 655#ifdef KTRACE 656 if (KTRPOINT(p, KTR_CSW)) 657 ktrcsw(p->p_tracep, 0, 0); 658#endif 659 PROC_LOCK(p); 660 if (SIGISMEMBER(p->p_sigacts->ps_sigintr, sig)) 661 rval = EINTR; 662 else 663 rval = ERESTART; 664 PROC_UNLOCK(p); 665 goto out; 666 } 667#ifdef KTRACE 668 if (KTRPOINT(p, KTR_CSW)) 669 ktrcsw(p->p_tracep, 0, 0); 670#endif 671 } else { 672 /* 673 * If as_priority is 0, mawait() has been called without an 674 * intervening asleep(). We are still effectively a NOP, 675 * but we call mi_switch() for safety. 676 */ 677 678 if (p->p_asleep.as_priority == 0) { 679 p->p_stats->p_ru.ru_nvcsw++; 680 mi_switch(); 681 } 682 mtx_unlock_spin(&sched_lock); 683 splx(s); 684 } 685 686 /* 687 * clear p_asleep.as_priority as an indication that mawait() has been 688 * called. If mawait() is called again without an intervening asleep(), 689 * mawait() is still effectively a NOP but the above mi_switch() code 690 * is triggered as a safety. 691 */ 692 p->p_asleep.as_priority = 0; 693 694out: 695 PICKUP_GIANT(); 696 if (mtx != NULL) { 697 mtx_lock(mtx); 698 WITNESS_RESTORE(&mtx->mtx_object, mtx); 699 } 700 return (rval); 701} 702 703/* 704 * Implement timeout for msleep or asleep()/mawait() 705 * 706 * If process hasn't been awakened (wchan non-zero), 707 * set timeout flag and undo the sleep. If proc 708 * is stopped, just unsleep so it will remain stopped. 709 * MP-safe, called without the Giant mutex. 710 */ 711static void 712endtsleep(arg) 713 void *arg; 714{ 715 register struct proc *p; 716 int s; 717 718 p = (struct proc *)arg; 719 CTR4(KTR_PROC, 720 "endtsleep: proc %p (pid %d, %s), schedlock %p", 721 p, p->p_pid, p->p_comm, (void *) sched_lock.mtx_lock); 722 s = splhigh(); 723 mtx_lock_spin(&sched_lock); 724 if (p->p_wchan) { 725 if (p->p_stat == SSLEEP) 726 setrunnable(p); 727 else 728 unsleep(p); 729 p->p_sflag |= PS_TIMEOUT; 730 } 731 mtx_unlock_spin(&sched_lock); 732 splx(s); 733} 734 735/* 736 * Remove a process from its wait queue 737 */ 738void 739unsleep(p) 740 register struct proc *p; 741{ 742 int s; 743 744 s = splhigh(); 745 mtx_lock_spin(&sched_lock); 746 if (p->p_wchan) { 747 TAILQ_REMOVE(&slpque[LOOKUP(p->p_wchan)], p, p_slpq); 748 p->p_wchan = NULL; 749 } 750 mtx_unlock_spin(&sched_lock); 751 splx(s); 752} 753 754/* 755 * Make all processes sleeping on the specified identifier runnable. 756 */ 757void 758wakeup(ident) 759 register void *ident; 760{ 761 register struct slpquehead *qp; 762 register struct proc *p; 763 int s; 764 765 s = splhigh(); 766 mtx_lock_spin(&sched_lock); 767 qp = &slpque[LOOKUP(ident)]; 768restart: 769 TAILQ_FOREACH(p, qp, p_slpq) { 770 if (p->p_wchan == ident) { 771 TAILQ_REMOVE(qp, p, p_slpq); 772 p->p_wchan = NULL; 773 if (p->p_stat == SSLEEP) { 774 /* OPTIMIZED EXPANSION OF setrunnable(p); */ 775 CTR4(KTR_PROC, 776 "wakeup: proc %p (pid %d, %s), schedlock %p", 777 p, p->p_pid, p->p_comm, (void *) sched_lock.mtx_lock); 778 if (p->p_slptime > 1) 779 updatepri(p); 780 p->p_slptime = 0; 781 p->p_stat = SRUN; 782 if (p->p_sflag & PS_INMEM) { 783 setrunqueue(p); 784 maybe_resched(p); 785 } else { 786 p->p_sflag |= PS_SWAPINREQ; 787 wakeup((caddr_t)&proc0); 788 } 789 /* END INLINE EXPANSION */ 790 goto restart; 791 } 792 } 793 } 794 mtx_unlock_spin(&sched_lock); 795 splx(s); 796} 797 798/* 799 * Make a process sleeping on the specified identifier runnable. 800 * May wake more than one process if a target process is currently 801 * swapped out. 802 */ 803void 804wakeup_one(ident) 805 register void *ident; 806{ 807 register struct slpquehead *qp; 808 register struct proc *p; 809 int s; 810 811 s = splhigh(); 812 mtx_lock_spin(&sched_lock); 813 qp = &slpque[LOOKUP(ident)]; 814 815 TAILQ_FOREACH(p, qp, p_slpq) { 816 if (p->p_wchan == ident) { 817 TAILQ_REMOVE(qp, p, p_slpq); 818 p->p_wchan = NULL; 819 if (p->p_stat == SSLEEP) { 820 /* OPTIMIZED EXPANSION OF setrunnable(p); */ 821 CTR4(KTR_PROC, 822 "wakeup1: proc %p (pid %d, %s), schedlock %p", 823 p, p->p_pid, p->p_comm, (void *) sched_lock.mtx_lock); 824 if (p->p_slptime > 1) 825 updatepri(p); 826 p->p_slptime = 0; 827 p->p_stat = SRUN; 828 if (p->p_sflag & PS_INMEM) { 829 setrunqueue(p); 830 maybe_resched(p); 831 break; 832 } else { 833 p->p_sflag |= PS_SWAPINREQ; 834 wakeup((caddr_t)&proc0); 835 } 836 /* END INLINE EXPANSION */ 837 } 838 } 839 } 840 mtx_unlock_spin(&sched_lock); 841 splx(s); 842} 843 844/* 845 * The machine independent parts of mi_switch(). 846 * Must be called at splstatclock() or higher. 847 */ 848void 849mi_switch() 850{ 851 struct timeval new_switchtime; 852 register struct proc *p = curproc; /* XXX */ 853#if 0 854 register struct rlimit *rlim; 855#endif 856 u_int sched_nest; 857 858 mtx_assert(&sched_lock, MA_OWNED | MA_NOTRECURSED); 859 860 /* 861 * Compute the amount of time during which the current 862 * process was running, and add that to its total so far. 863 */ 864 microuptime(&new_switchtime); 865 if (timevalcmp(&new_switchtime, PCPU_PTR(switchtime), <)) { 866#if 0 867 /* XXX: This doesn't play well with sched_lock right now. */ 868 printf("microuptime() went backwards (%ld.%06ld -> %ld.%06ld)\n", 869 PCPU_GET(switchtime.tv_sec), PCPU_GET(switchtime.tv_usec), 870 new_switchtime.tv_sec, new_switchtime.tv_usec); 871#endif 872 new_switchtime = PCPU_GET(switchtime); 873 } else { 874 p->p_runtime += (new_switchtime.tv_usec - PCPU_GET(switchtime.tv_usec)) + 875 (new_switchtime.tv_sec - PCPU_GET(switchtime.tv_sec)) * 876 (int64_t)1000000; 877 } 878 879#if 0 880 /* 881 * Check if the process exceeds its cpu resource allocation. 882 * If over max, kill it. 883 * 884 * XXX drop sched_lock, pickup Giant 885 */ 886 if (p->p_stat != SZOMB && p->p_limit->p_cpulimit != RLIM_INFINITY && 887 p->p_runtime > p->p_limit->p_cpulimit) { 888 rlim = &p->p_rlimit[RLIMIT_CPU]; 889 if (p->p_runtime / (rlim_t)1000000 >= rlim->rlim_max) { 890 mtx_unlock_spin(&sched_lock); 891 PROC_LOCK(p); 892 killproc(p, "exceeded maximum CPU limit"); 893 mtx_lock_spin(&sched_lock); 894 PROC_UNLOCK_NOSWITCH(p); 895 } else { 896 mtx_unlock_spin(&sched_lock); 897 PROC_LOCK(p); 898 psignal(p, SIGXCPU); 899 mtx_lock_spin(&sched_lock); 900 PROC_UNLOCK_NOSWITCH(p); 901 if (rlim->rlim_cur < rlim->rlim_max) { 902 /* XXX: we should make a private copy */ 903 rlim->rlim_cur += 5; 904 } 905 } 906 } 907#endif 908 909 /* 910 * Pick a new current process and record its start time. 911 */ 912 cnt.v_swtch++; 913 PCPU_SET(switchtime, new_switchtime); 914 CTR4(KTR_PROC, "mi_switch: old proc %p (pid %d, %s), schedlock %p", 915 p, p->p_pid, p->p_comm, (void *) sched_lock.mtx_lock); 916 sched_nest = sched_lock.mtx_recurse; 917 curproc->p_lastcpu = curproc->p_oncpu; 918 curproc->p_oncpu = NOCPU; 919 clear_resched(curproc); 920 cpu_switch(); 921 curproc->p_oncpu = PCPU_GET(cpuid); 922 sched_lock.mtx_recurse = sched_nest; 923 sched_lock.mtx_lock = (uintptr_t)curproc; 924 CTR4(KTR_PROC, "mi_switch: new proc %p (pid %d, %s), schedlock %p", 925 p, p->p_pid, p->p_comm, (void *) sched_lock.mtx_lock); 926 if (PCPU_GET(switchtime.tv_sec) == 0) 927 microuptime(PCPU_PTR(switchtime)); 928 PCPU_SET(switchticks, ticks); 929} 930 931/* 932 * Change process state to be runnable, 933 * placing it on the run queue if it is in memory, 934 * and awakening the swapper if it isn't in memory. 935 */ 936void 937setrunnable(p) 938 register struct proc *p; 939{ 940 register int s; 941 942 s = splhigh(); 943 mtx_lock_spin(&sched_lock); 944 switch (p->p_stat) { 945 case 0: 946 case SRUN: 947 case SZOMB: 948 case SWAIT: 949 default: 950 panic("setrunnable"); 951 case SSTOP: 952 case SSLEEP: /* e.g. when sending signals */ 953 if (p->p_sflag & PS_CVWAITQ) 954 cv_waitq_remove(p); 955 else 956 unsleep(p); 957 break; 958 959 case SIDL: 960 break; 961 } 962 p->p_stat = SRUN; 963 if (p->p_sflag & PS_INMEM) 964 setrunqueue(p); 965 splx(s); 966 if (p->p_slptime > 1) 967 updatepri(p); 968 p->p_slptime = 0; 969 if ((p->p_sflag & PS_INMEM) == 0) { 970 p->p_sflag |= PS_SWAPINREQ; 971 wakeup((caddr_t)&proc0); 972 } 973 else 974 maybe_resched(p); 975 mtx_unlock_spin(&sched_lock); 976} 977 978/* 979 * Compute the priority of a process when running in user mode. 980 * Arrange to reschedule if the resulting priority is better 981 * than that of the current process. 982 */ 983void 984resetpriority(p) 985 register struct proc *p; 986{ 987 register unsigned int newpriority; 988 989 mtx_lock_spin(&sched_lock); 990 if (p->p_pri.pri_class == PRI_TIMESHARE) { 991 newpriority = PUSER + p->p_estcpu / INVERSE_ESTCPU_WEIGHT + 992 NICE_WEIGHT * (p->p_nice - PRIO_MIN); 993 newpriority = min(max(newpriority, PRI_MIN_TIMESHARE), 994 PRI_MAX_TIMESHARE); 995 p->p_pri.pri_user = newpriority; 996 } 997 maybe_resched(p); 998 mtx_unlock_spin(&sched_lock); 999} 1000 1001/* ARGSUSED */ 1002static void 1003sched_setup(dummy) 1004 void *dummy; 1005{ 1006 1007 callout_init(&schedcpu_callout, 1); 1008 callout_init(&roundrobin_callout, 0); 1009 1010 /* Kick off timeout driven events by calling first time. */ 1011 roundrobin(NULL); 1012 schedcpu(NULL); 1013} 1014 1015/* 1016 * We adjust the priority of the current process. The priority of 1017 * a process gets worse as it accumulates CPU time. The cpu usage 1018 * estimator (p_estcpu) is increased here. resetpriority() will 1019 * compute a different priority each time p_estcpu increases by 1020 * INVERSE_ESTCPU_WEIGHT 1021 * (until MAXPRI is reached). The cpu usage estimator ramps up 1022 * quite quickly when the process is running (linearly), and decays 1023 * away exponentially, at a rate which is proportionally slower when 1024 * the system is busy. The basic principle is that the system will 1025 * 90% forget that the process used a lot of CPU time in 5 * loadav 1026 * seconds. This causes the system to favor processes which haven't 1027 * run much recently, and to round-robin among other processes. 1028 */ 1029void 1030schedclock(p) 1031 struct proc *p; 1032{ 1033 1034 p->p_cpticks++; 1035 p->p_estcpu = ESTCPULIM(p->p_estcpu + 1); 1036 if ((p->p_estcpu % INVERSE_ESTCPU_WEIGHT) == 0) { 1037 resetpriority(p); 1038 if (p->p_pri.pri_level >= PUSER) 1039 p->p_pri.pri_level = p->p_pri.pri_user; 1040 } 1041} 1042 1043/* 1044 * General purpose yield system call 1045 */ 1046int 1047yield(struct proc *p, struct yield_args *uap) 1048{ 1049 int s; 1050 1051 p->p_retval[0] = 0; 1052 1053 s = splhigh(); 1054 mtx_lock_spin(&sched_lock); 1055 DROP_GIANT_NOSWITCH(); 1056 p->p_pri.pri_level = PRI_MAX_TIMESHARE; 1057 setrunqueue(p); 1058 p->p_stats->p_ru.ru_nvcsw++; 1059 mi_switch(); 1060 mtx_unlock_spin(&sched_lock); 1061 PICKUP_GIANT(); 1062 splx(s); 1063 1064 return (0); 1065} 1066