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: src/sys/kern/kern_synch.c,v 1.87.2.6 2002/10/13 07:29:53 kbyanc Exp $ 40 * $DragonFly: src/sys/kern/kern_synch.c,v 1.91 2008/09/09 04:06:13 dillon Exp $ 41 */ 42 43 #include "opt_ktrace.h" 44 45 #include <sys/param.h> 46 #include <sys/systm.h> 47 #include <sys/proc.h> 48 #include <sys/kernel.h> 49 #include <sys/signalvar.h> 50 #include <sys/resourcevar.h> 51 #include <sys/vmmeter.h> 52 #include <sys/sysctl.h> 53 #include <sys/lock.h> 54 #ifdef KTRACE 55 #include <sys/uio.h> 56 #include <sys/ktrace.h> 57 #endif 58 #include <sys/xwait.h> 59 #include <sys/ktr.h> 60 #include <sys/serialize.h> 61 62 #include <sys/signal2.h> 63 #include <sys/thread2.h> 64 #include <sys/spinlock2.h> 65 #include <sys/mutex2.h> 66 #include <sys/mplock2.h> 67 68 #include <machine/cpu.h> 69 #include <machine/smp.h> 70 71 TAILQ_HEAD(tslpque, thread); 72 73 static void sched_setup (void *dummy); 74 SYSINIT(sched_setup, SI_SUB_KICK_SCHEDULER, SI_ORDER_FIRST, sched_setup, NULL) 75 76 int hogticks; 77 int lbolt; 78 int lbolt_syncer; 79 int sched_quantum; /* Roundrobin scheduling quantum in ticks. */ 80 int ncpus; 81 int ncpus2, ncpus2_shift, ncpus2_mask; 82 int ncpus_fit, ncpus_fit_mask; 83 int safepri; 84 int tsleep_now_works; 85 86 static struct callout loadav_callout; 87 static struct callout schedcpu_callout; 88 MALLOC_DEFINE(M_TSLEEP, "tslpque", "tsleep queues"); 89 90 #if !defined(KTR_TSLEEP) 91 #define KTR_TSLEEP KTR_ALL 92 #endif 93 KTR_INFO_MASTER(tsleep); 94 KTR_INFO(KTR_TSLEEP, tsleep, tsleep_beg, 0, "tsleep enter %p", sizeof(void *)); 95 KTR_INFO(KTR_TSLEEP, tsleep, tsleep_end, 1, "tsleep exit", 0); 96 KTR_INFO(KTR_TSLEEP, tsleep, wakeup_beg, 2, "wakeup enter %p", sizeof(void *)); 97 KTR_INFO(KTR_TSLEEP, tsleep, wakeup_end, 3, "wakeup exit", 0); 98 KTR_INFO(KTR_TSLEEP, tsleep, ilockfail, 4, "interlock failed %p", sizeof(void *)); 99 100 #define logtsleep1(name) KTR_LOG(tsleep_ ## name) 101 #define logtsleep2(name, val) KTR_LOG(tsleep_ ## name, val) 102 103 struct loadavg averunnable = 104 { {0, 0, 0}, FSCALE }; /* load average, of runnable procs */ 105 /* 106 * Constants for averages over 1, 5, and 15 minutes 107 * when sampling at 5 second intervals. 108 */ 109 static fixpt_t cexp[3] = { 110 0.9200444146293232 * FSCALE, /* exp(-1/12) */ 111 0.9834714538216174 * FSCALE, /* exp(-1/60) */ 112 0.9944598480048967 * FSCALE, /* exp(-1/180) */ 113 }; 114 115 static void endtsleep (void *); 116 static void loadav (void *arg); 117 static void schedcpu (void *arg); 118 #ifdef SMP 119 static void tsleep_wakeup(struct thread *td); 120 #endif 121 122 /* 123 * Adjust the scheduler quantum. The quantum is specified in microseconds. 124 * Note that 'tick' is in microseconds per tick. 125 */ 126 static int 127 sysctl_kern_quantum(SYSCTL_HANDLER_ARGS) 128 { 129 int error, new_val; 130 131 new_val = sched_quantum * ustick; 132 error = sysctl_handle_int(oidp, &new_val, 0, req); 133 if (error != 0 || req->newptr == NULL) 134 return (error); 135 if (new_val < ustick) 136 return (EINVAL); 137 sched_quantum = new_val / ustick; 138 hogticks = 2 * sched_quantum; 139 return (0); 140 } 141 142 SYSCTL_PROC(_kern, OID_AUTO, quantum, CTLTYPE_INT|CTLFLAG_RW, 143 0, sizeof sched_quantum, sysctl_kern_quantum, "I", ""); 144 145 /* 146 * If `ccpu' is not equal to `exp(-1/20)' and you still want to use the 147 * faster/more-accurate formula, you'll have to estimate CCPU_SHIFT below 148 * and possibly adjust FSHIFT in "param.h" so that (FSHIFT >= CCPU_SHIFT). 149 * 150 * To estimate CCPU_SHIFT for exp(-1/20), the following formula was used: 151 * 1 - exp(-1/20) ~= 0.0487 ~= 0.0488 == 1 (fixed pt, *11* bits). 152 * 153 * If you don't want to bother with the faster/more-accurate formula, you 154 * can set CCPU_SHIFT to (FSHIFT + 1) which will use a slower/less-accurate 155 * (more general) method of calculating the %age of CPU used by a process. 156 * 157 * decay 95% of `lwp_pctcpu' in 60 seconds; see CCPU_SHIFT before changing 158 */ 159 #define CCPU_SHIFT 11 160 161 static fixpt_t ccpu = 0.95122942450071400909 * FSCALE; /* exp(-1/20) */ 162 SYSCTL_INT(_kern, OID_AUTO, ccpu, CTLFLAG_RD, &ccpu, 0, ""); 163 164 /* 165 * kernel uses `FSCALE', userland (SHOULD) use kern.fscale 166 */ 167 int fscale __unused = FSCALE; /* exported to systat */ 168 SYSCTL_INT(_kern, OID_AUTO, fscale, CTLFLAG_RD, 0, FSCALE, ""); 169 170 /* 171 * Recompute process priorities, once a second. 172 * 173 * Since the userland schedulers are typically event oriented, if the 174 * estcpu calculation at wakeup() time is not sufficient to make a 175 * process runnable relative to other processes in the system we have 176 * a 1-second recalc to help out. 177 * 178 * This code also allows us to store sysclock_t data in the process structure 179 * without fear of an overrun, since sysclock_t are guarenteed to hold 180 * several seconds worth of count. 181 * 182 * WARNING! callouts can preempt normal threads. However, they will not 183 * preempt a thread holding a spinlock so we *can* safely use spinlocks. 184 */ 185 static int schedcpu_stats(struct proc *p, void *data __unused); 186 static int schedcpu_resource(struct proc *p, void *data __unused); 187 188 static void 189 schedcpu(void *arg) 190 { 191 allproc_scan(schedcpu_stats, NULL); 192 allproc_scan(schedcpu_resource, NULL); 193 wakeup((caddr_t)&lbolt); 194 wakeup((caddr_t)&lbolt_syncer); 195 callout_reset(&schedcpu_callout, hz, schedcpu, NULL); 196 } 197 198 /* 199 * General process statistics once a second 200 */ 201 static int 202 schedcpu_stats(struct proc *p, void *data __unused) 203 { 204 struct lwp *lp; 205 206 crit_enter(); 207 p->p_swtime++; 208 FOREACH_LWP_IN_PROC(lp, p) { 209 if (lp->lwp_stat == LSSLEEP) 210 lp->lwp_slptime++; 211 212 /* 213 * Only recalculate processes that are active or have slept 214 * less then 2 seconds. The schedulers understand this. 215 */ 216 if (lp->lwp_slptime <= 1) { 217 p->p_usched->recalculate(lp); 218 } else { 219 lp->lwp_pctcpu = (lp->lwp_pctcpu * ccpu) >> FSHIFT; 220 } 221 } 222 crit_exit(); 223 return(0); 224 } 225 226 /* 227 * Resource checks. XXX break out since ksignal/killproc can block, 228 * limiting us to one process killed per second. There is probably 229 * a better way. 230 */ 231 static int 232 schedcpu_resource(struct proc *p, void *data __unused) 233 { 234 u_int64_t ttime; 235 struct lwp *lp; 236 237 crit_enter(); 238 if (p->p_stat == SIDL || 239 p->p_stat == SZOMB || 240 p->p_limit == NULL 241 ) { 242 crit_exit(); 243 return(0); 244 } 245 246 ttime = 0; 247 FOREACH_LWP_IN_PROC(lp, p) { 248 /* 249 * We may have caught an lp in the middle of being 250 * created, lwp_thread can be NULL. 251 */ 252 if (lp->lwp_thread) { 253 ttime += lp->lwp_thread->td_sticks; 254 ttime += lp->lwp_thread->td_uticks; 255 } 256 } 257 258 switch(plimit_testcpulimit(p->p_limit, ttime)) { 259 case PLIMIT_TESTCPU_KILL: 260 killproc(p, "exceeded maximum CPU limit"); 261 break; 262 case PLIMIT_TESTCPU_XCPU: 263 if ((p->p_flag & P_XCPU) == 0) { 264 p->p_flag |= P_XCPU; 265 ksignal(p, SIGXCPU); 266 } 267 break; 268 default: 269 break; 270 } 271 crit_exit(); 272 return(0); 273 } 274 275 /* 276 * This is only used by ps. Generate a cpu percentage use over 277 * a period of one second. 278 * 279 * MPSAFE 280 */ 281 void 282 updatepcpu(struct lwp *lp, int cpticks, int ttlticks) 283 { 284 fixpt_t acc; 285 int remticks; 286 287 acc = (cpticks << FSHIFT) / ttlticks; 288 if (ttlticks >= ESTCPUFREQ) { 289 lp->lwp_pctcpu = acc; 290 } else { 291 remticks = ESTCPUFREQ - ttlticks; 292 lp->lwp_pctcpu = (acc * ttlticks + lp->lwp_pctcpu * remticks) / 293 ESTCPUFREQ; 294 } 295 } 296 297 /* 298 * tsleep/wakeup hash table parameters. Try to find the sweet spot for 299 * like addresses being slept on. 300 */ 301 #define TABLESIZE 1024 302 #define LOOKUP(x) (((intptr_t)(x) >> 6) & (TABLESIZE - 1)) 303 304 static cpumask_t slpque_cpumasks[TABLESIZE]; 305 306 /* 307 * General scheduler initialization. We force a reschedule 25 times 308 * a second by default. Note that cpu0 is initialized in early boot and 309 * cannot make any high level calls. 310 * 311 * Each cpu has its own sleep queue. 312 */ 313 void 314 sleep_gdinit(globaldata_t gd) 315 { 316 static struct tslpque slpque_cpu0[TABLESIZE]; 317 int i; 318 319 if (gd->gd_cpuid == 0) { 320 sched_quantum = (hz + 24) / 25; 321 hogticks = 2 * sched_quantum; 322 323 gd->gd_tsleep_hash = slpque_cpu0; 324 } else { 325 gd->gd_tsleep_hash = kmalloc(sizeof(slpque_cpu0), 326 M_TSLEEP, M_WAITOK | M_ZERO); 327 } 328 for (i = 0; i < TABLESIZE; ++i) 329 TAILQ_INIT(&gd->gd_tsleep_hash[i]); 330 } 331 332 /* 333 * This is a dandy function that allows us to interlock tsleep/wakeup 334 * operations with unspecified upper level locks, such as lockmgr locks, 335 * simply by holding a critical section. The sequence is: 336 * 337 * (acquire upper level lock) 338 * tsleep_interlock(blah) 339 * (release upper level lock) 340 * tsleep(blah, ...) 341 * 342 * Basically this functions queues us on the tsleep queue without actually 343 * descheduling us. When tsleep() is later called with PINTERLOCK it 344 * assumes the thread was already queued, otherwise it queues it there. 345 * 346 * Thus it is possible to receive the wakeup prior to going to sleep and 347 * the race conditions are covered. 348 */ 349 static __inline void 350 _tsleep_interlock(globaldata_t gd, void *ident, int flags) 351 { 352 thread_t td = gd->gd_curthread; 353 int id; 354 355 crit_enter_quick(td); 356 if (td->td_flags & TDF_TSLEEPQ) { 357 id = LOOKUP(td->td_wchan); 358 TAILQ_REMOVE(&gd->gd_tsleep_hash[id], td, td_sleepq); 359 if (TAILQ_FIRST(&gd->gd_tsleep_hash[id]) == NULL) 360 atomic_clear_int(&slpque_cpumasks[id], gd->gd_cpumask); 361 } else { 362 td->td_flags |= TDF_TSLEEPQ; 363 } 364 id = LOOKUP(ident); 365 TAILQ_INSERT_TAIL(&gd->gd_tsleep_hash[id], td, td_sleepq); 366 atomic_set_int(&slpque_cpumasks[id], gd->gd_cpumask); 367 td->td_wchan = ident; 368 td->td_wdomain = flags & PDOMAIN_MASK; 369 crit_exit_quick(td); 370 } 371 372 void 373 tsleep_interlock(void *ident, int flags) 374 { 375 _tsleep_interlock(mycpu, ident, flags); 376 } 377 378 /* 379 * Remove thread from sleepq. Must be called with a critical section held. 380 */ 381 static __inline void 382 _tsleep_remove(thread_t td) 383 { 384 globaldata_t gd = mycpu; 385 int id; 386 387 KKASSERT(td->td_gd == gd); 388 if (td->td_flags & TDF_TSLEEPQ) { 389 td->td_flags &= ~TDF_TSLEEPQ; 390 id = LOOKUP(td->td_wchan); 391 TAILQ_REMOVE(&gd->gd_tsleep_hash[id], td, td_sleepq); 392 if (TAILQ_FIRST(&gd->gd_tsleep_hash[id]) == NULL) 393 atomic_clear_int(&slpque_cpumasks[id], gd->gd_cpumask); 394 td->td_wchan = NULL; 395 td->td_wdomain = 0; 396 } 397 } 398 399 void 400 tsleep_remove(thread_t td) 401 { 402 _tsleep_remove(td); 403 } 404 405 /* 406 * This function removes a thread from the tsleep queue and schedules 407 * it. This function may act asynchronously. The target thread may be 408 * sleeping on a different cpu. 409 * 410 * This function mus be called while in a critical section but if the 411 * target thread is sleeping on a different cpu we cannot safely probe 412 * td_flags. 413 */ 414 static __inline 415 void 416 _tsleep_wakeup(struct thread *td) 417 { 418 #ifdef SMP 419 globaldata_t gd = mycpu; 420 421 if (td->td_gd != gd) { 422 lwkt_send_ipiq(td->td_gd, (ipifunc1_t)tsleep_wakeup, td); 423 return; 424 } 425 #endif 426 _tsleep_remove(td); 427 if (td->td_flags & TDF_TSLEEP_DESCHEDULED) { 428 td->td_flags &= ~TDF_TSLEEP_DESCHEDULED; 429 lwkt_schedule(td); 430 } 431 } 432 433 #ifdef SMP 434 static 435 void 436 tsleep_wakeup(struct thread *td) 437 { 438 _tsleep_wakeup(td); 439 } 440 #endif 441 442 443 /* 444 * General sleep call. Suspends the current process until a wakeup is 445 * performed on the specified identifier. The process will then be made 446 * runnable with the specified priority. Sleeps at most timo/hz seconds 447 * (0 means no timeout). If flags includes PCATCH flag, signals are checked 448 * before and after sleeping, else signals are not checked. Returns 0 if 449 * awakened, EWOULDBLOCK if the timeout expires. If PCATCH is set and a 450 * signal needs to be delivered, ERESTART is returned if the current system 451 * call should be restarted if possible, and EINTR is returned if the system 452 * call should be interrupted by the signal (return EINTR). 453 * 454 * Note that if we are a process, we release_curproc() before messing with 455 * the LWKT scheduler. 456 * 457 * During autoconfiguration or after a panic, a sleep will simply 458 * lower the priority briefly to allow interrupts, then return. 459 */ 460 int 461 tsleep(void *ident, int flags, const char *wmesg, int timo) 462 { 463 struct thread *td = curthread; 464 struct lwp *lp = td->td_lwp; 465 struct proc *p = td->td_proc; /* may be NULL */ 466 globaldata_t gd; 467 int sig; 468 int catch; 469 int id; 470 int error; 471 int oldpri; 472 struct callout thandle; 473 474 /* 475 * NOTE: removed KTRPOINT, it could cause races due to blocking 476 * even in stable. Just scrap it for now. 477 */ 478 if (tsleep_now_works == 0 || panicstr) { 479 /* 480 * After a panic, or before we actually have an operational 481 * softclock, just give interrupts a chance, then just return; 482 * 483 * don't run any other procs or panic below, 484 * in case this is the idle process and already asleep. 485 */ 486 splz(); 487 oldpri = td->td_pri & TDPRI_MASK; 488 lwkt_setpri_self(safepri); 489 lwkt_switch(); 490 lwkt_setpri_self(oldpri); 491 return (0); 492 } 493 logtsleep2(tsleep_beg, ident); 494 gd = td->td_gd; 495 KKASSERT(td != &gd->gd_idlethread); /* you must be kidding! */ 496 497 /* 498 * NOTE: all of this occurs on the current cpu, including any 499 * callout-based wakeups, so a critical section is a sufficient 500 * interlock. 501 * 502 * The entire sequence through to where we actually sleep must 503 * run without breaking the critical section. 504 */ 505 catch = flags & PCATCH; 506 error = 0; 507 sig = 0; 508 509 crit_enter_quick(td); 510 511 KASSERT(ident != NULL, ("tsleep: no ident")); 512 KASSERT(lp == NULL || 513 lp->lwp_stat == LSRUN || /* Obvious */ 514 lp->lwp_stat == LSSTOP, /* Set in tstop */ 515 ("tsleep %p %s %d", 516 ident, wmesg, lp->lwp_stat)); 517 518 /* 519 * Setup for the current process (if this is a process). 520 */ 521 if (lp) { 522 if (catch) { 523 /* 524 * Early termination if PCATCH was set and a 525 * signal is pending, interlocked with the 526 * critical section. 527 * 528 * Early termination only occurs when tsleep() is 529 * entered while in a normal LSRUN state. 530 */ 531 if ((sig = CURSIG(lp)) != 0) 532 goto resume; 533 534 /* 535 * Early termination if PCATCH was set and a 536 * mailbox signal was possibly delivered prior to 537 * the system call even being made, in order to 538 * allow the user to interlock without having to 539 * make additional system calls. 540 */ 541 if (p->p_flag & P_MAILBOX) 542 goto resume; 543 544 /* 545 * Causes ksignal to wake us up when. 546 */ 547 lp->lwp_flag |= LWP_SINTR; 548 } 549 } 550 551 /* 552 * We interlock the sleep queue if the caller has not already done 553 * it for us. 554 */ 555 if ((flags & PINTERLOCKED) == 0) { 556 id = LOOKUP(ident); 557 _tsleep_interlock(gd, ident, flags); 558 } 559 560 /* 561 * 562 * If no interlock was set we do an integrated interlock here. 563 * Make sure the current process has been untangled from 564 * the userland scheduler and initialize slptime to start 565 * counting. We must interlock the sleep queue before doing 566 * this to avoid wakeup/process-ipi races which can occur under 567 * heavy loads. 568 */ 569 if (lp) { 570 p->p_usched->release_curproc(lp); 571 lp->lwp_slptime = 0; 572 } 573 574 /* 575 * If the interlocked flag is set but our cpu bit in the slpqueue 576 * is no longer set, then a wakeup was processed inbetween the 577 * tsleep_interlock() (ours or the callers), and here. This can 578 * occur under numerous circumstances including when we release the 579 * current process. 580 * 581 * Extreme loads can cause the sending of an IPI (e.g. wakeup()'s) 582 * to process incoming IPIs, thus draining incoming wakeups. 583 */ 584 if ((td->td_flags & TDF_TSLEEPQ) == 0) { 585 logtsleep2(ilockfail, ident); 586 goto resume; 587 } 588 589 /* 590 * scheduling is blocked while in a critical section. Coincide 591 * the descheduled-by-tsleep flag with the descheduling of the 592 * lwkt. 593 */ 594 lwkt_deschedule_self(td); 595 td->td_flags |= TDF_TSLEEP_DESCHEDULED; 596 td->td_wmesg = wmesg; 597 598 /* 599 * Setup the timeout, if any 600 */ 601 if (timo) { 602 callout_init(&thandle); 603 callout_reset(&thandle, timo, endtsleep, td); 604 } 605 606 /* 607 * Beddy bye bye. 608 */ 609 if (lp) { 610 /* 611 * Ok, we are sleeping. Place us in the SSLEEP state. 612 */ 613 KKASSERT((lp->lwp_flag & LWP_ONRUNQ) == 0); 614 /* 615 * tstop() sets LSSTOP, so don't fiddle with that. 616 */ 617 if (lp->lwp_stat != LSSTOP) 618 lp->lwp_stat = LSSLEEP; 619 lp->lwp_ru.ru_nvcsw++; 620 lwkt_switch(); 621 622 /* 623 * And when we are woken up, put us back in LSRUN. If we 624 * slept for over a second, recalculate our estcpu. 625 */ 626 lp->lwp_stat = LSRUN; 627 if (lp->lwp_slptime) 628 p->p_usched->recalculate(lp); 629 lp->lwp_slptime = 0; 630 } else { 631 lwkt_switch(); 632 } 633 634 /* 635 * Make sure we haven't switched cpus while we were asleep. It's 636 * not supposed to happen. Cleanup our temporary flags. 637 */ 638 KKASSERT(gd == td->td_gd); 639 640 /* 641 * Cleanup the timeout. 642 */ 643 if (timo) { 644 if (td->td_flags & TDF_TIMEOUT) { 645 td->td_flags &= ~TDF_TIMEOUT; 646 error = EWOULDBLOCK; 647 } else { 648 callout_stop(&thandle); 649 } 650 } 651 652 /* 653 * Make sure we have been removed from the sleepq. This should 654 * have been done for us already. 655 */ 656 _tsleep_remove(td); 657 td->td_wmesg = NULL; 658 if (td->td_flags & TDF_TSLEEP_DESCHEDULED) { 659 td->td_flags &= ~TDF_TSLEEP_DESCHEDULED; 660 kprintf("td %p (%s) unexpectedly rescheduled\n", 661 td, td->td_comm); 662 } 663 664 /* 665 * Figure out the correct error return. If interrupted by a 666 * signal we want to return EINTR or ERESTART. 667 * 668 * If P_MAILBOX is set no automatic system call restart occurs 669 * and we return EINTR. P_MAILBOX is meant to be used as an 670 * interlock, the user must poll it prior to any system call 671 * that it wishes to interlock a mailbox signal against since 672 * the flag is cleared on *any* system call that sleeps. 673 */ 674 resume: 675 if (p) { 676 if (catch && error == 0) { 677 if ((p->p_flag & P_MAILBOX) && sig == 0) { 678 error = EINTR; 679 } else if (sig != 0 || (sig = CURSIG(lp))) { 680 if (SIGISMEMBER(p->p_sigacts->ps_sigintr, sig)) 681 error = EINTR; 682 else 683 error = ERESTART; 684 } 685 } 686 lp->lwp_flag &= ~(LWP_BREAKTSLEEP | LWP_SINTR); 687 p->p_flag &= ~P_MAILBOX; 688 } 689 logtsleep1(tsleep_end); 690 crit_exit_quick(td); 691 return (error); 692 } 693 694 /* 695 * Interlocked spinlock sleep. An exclusively held spinlock must 696 * be passed to ssleep(). The function will atomically release the 697 * spinlock and tsleep on the ident, then reacquire the spinlock and 698 * return. 699 * 700 * This routine is fairly important along the critical path, so optimize it 701 * heavily. 702 */ 703 int 704 ssleep(void *ident, struct spinlock *spin, int flags, 705 const char *wmesg, int timo) 706 { 707 globaldata_t gd = mycpu; 708 int error; 709 710 _tsleep_interlock(gd, ident, flags); 711 spin_unlock_wr_quick(gd, spin); 712 error = tsleep(ident, flags | PINTERLOCKED, wmesg, timo); 713 spin_lock_wr_quick(gd, spin); 714 715 return (error); 716 } 717 718 int 719 lksleep(void *ident, struct lock *lock, int flags, 720 const char *wmesg, int timo) 721 { 722 globaldata_t gd = mycpu; 723 int error; 724 725 _tsleep_interlock(gd, ident, flags); 726 lockmgr(lock, LK_RELEASE); 727 error = tsleep(ident, flags | PINTERLOCKED, wmesg, timo); 728 lockmgr(lock, LK_EXCLUSIVE); 729 730 return (error); 731 } 732 733 /* 734 * Interlocked mutex sleep. An exclusively held mutex must be passed 735 * to mtxsleep(). The function will atomically release the mutex 736 * and tsleep on the ident, then reacquire the mutex and return. 737 */ 738 int 739 mtxsleep(void *ident, struct mtx *mtx, int flags, 740 const char *wmesg, int timo) 741 { 742 globaldata_t gd = mycpu; 743 int error; 744 745 _tsleep_interlock(gd, ident, flags); 746 mtx_unlock(mtx); 747 error = tsleep(ident, flags | PINTERLOCKED, wmesg, timo); 748 mtx_lock_ex_quick(mtx, wmesg); 749 750 return (error); 751 } 752 753 /* 754 * Interlocked serializer sleep. An exclusively held serializer must 755 * be passed to zsleep(). The function will atomically release 756 * the serializer and tsleep on the ident, then reacquire the serializer 757 * and return. 758 */ 759 int 760 zsleep(void *ident, struct lwkt_serialize *slz, int flags, 761 const char *wmesg, int timo) 762 { 763 globaldata_t gd = mycpu; 764 int ret; 765 766 ASSERT_SERIALIZED(slz); 767 768 _tsleep_interlock(gd, ident, flags); 769 lwkt_serialize_exit(slz); 770 ret = tsleep(ident, flags | PINTERLOCKED, wmesg, timo); 771 lwkt_serialize_enter(slz); 772 773 return ret; 774 } 775 776 /* 777 * Directly block on the LWKT thread by descheduling it. This 778 * is much faster then tsleep(), but the only legal way to wake 779 * us up is to directly schedule the thread. 780 * 781 * Setting TDF_SINTR will cause new signals to directly schedule us. 782 * 783 * This routine must be called while in a critical section. 784 */ 785 int 786 lwkt_sleep(const char *wmesg, int flags) 787 { 788 thread_t td = curthread; 789 int sig; 790 791 if ((flags & PCATCH) == 0 || td->td_lwp == NULL) { 792 td->td_flags |= TDF_BLOCKED; 793 td->td_wmesg = wmesg; 794 lwkt_deschedule_self(td); 795 lwkt_switch(); 796 td->td_wmesg = NULL; 797 td->td_flags &= ~TDF_BLOCKED; 798 return(0); 799 } 800 if ((sig = CURSIG(td->td_lwp)) != 0) { 801 if (SIGISMEMBER(td->td_proc->p_sigacts->ps_sigintr, sig)) 802 return(EINTR); 803 else 804 return(ERESTART); 805 806 } 807 td->td_flags |= TDF_BLOCKED | TDF_SINTR; 808 td->td_wmesg = wmesg; 809 lwkt_deschedule_self(td); 810 lwkt_switch(); 811 td->td_flags &= ~(TDF_BLOCKED | TDF_SINTR); 812 td->td_wmesg = NULL; 813 return(0); 814 } 815 816 /* 817 * Implement the timeout for tsleep. 818 * 819 * We set LWP_BREAKTSLEEP to indicate that an event has occured, but 820 * we only call setrunnable if the process is not stopped. 821 * 822 * This type of callout timeout is scheduled on the same cpu the process 823 * is sleeping on. Also, at the moment, the MP lock is held. 824 */ 825 static void 826 endtsleep(void *arg) 827 { 828 thread_t td = arg; 829 struct lwp *lp; 830 831 ASSERT_MP_LOCK_HELD(curthread); 832 crit_enter(); 833 834 /* 835 * cpu interlock. Thread flags are only manipulated on 836 * the cpu owning the thread. proc flags are only manipulated 837 * by the older of the MP lock. We have both. 838 */ 839 if (td->td_flags & TDF_TSLEEP_DESCHEDULED) { 840 td->td_flags |= TDF_TIMEOUT; 841 842 if ((lp = td->td_lwp) != NULL) { 843 lp->lwp_flag |= LWP_BREAKTSLEEP; 844 if (lp->lwp_proc->p_stat != SSTOP) 845 setrunnable(lp); 846 } else { 847 _tsleep_wakeup(td); 848 } 849 } 850 crit_exit(); 851 } 852 853 /* 854 * Make all processes sleeping on the specified identifier runnable. 855 * count may be zero or one only. 856 * 857 * The domain encodes the sleep/wakeup domain AND the first cpu to check 858 * (which is always the current cpu). As we iterate across cpus 859 * 860 * This call may run without the MP lock held. We can only manipulate thread 861 * state on the cpu owning the thread. We CANNOT manipulate process state 862 * at all. 863 */ 864 static void 865 _wakeup(void *ident, int domain) 866 { 867 struct tslpque *qp; 868 struct thread *td; 869 struct thread *ntd; 870 globaldata_t gd; 871 #ifdef SMP 872 cpumask_t mask; 873 #endif 874 int id; 875 876 crit_enter(); 877 logtsleep2(wakeup_beg, ident); 878 gd = mycpu; 879 id = LOOKUP(ident); 880 qp = &gd->gd_tsleep_hash[id]; 881 restart: 882 for (td = TAILQ_FIRST(qp); td != NULL; td = ntd) { 883 ntd = TAILQ_NEXT(td, td_sleepq); 884 if (td->td_wchan == ident && 885 td->td_wdomain == (domain & PDOMAIN_MASK) 886 ) { 887 KKASSERT(td->td_gd == gd); 888 _tsleep_remove(td); 889 if (td->td_flags & TDF_TSLEEP_DESCHEDULED) { 890 td->td_flags &= ~TDF_TSLEEP_DESCHEDULED; 891 lwkt_schedule(td); 892 if (domain & PWAKEUP_ONE) 893 goto done; 894 } 895 goto restart; 896 } 897 } 898 899 #ifdef SMP 900 /* 901 * We finished checking the current cpu but there still may be 902 * more work to do. Either wakeup_one was requested and no matching 903 * thread was found, or a normal wakeup was requested and we have 904 * to continue checking cpus. 905 * 906 * It should be noted that this scheme is actually less expensive then 907 * the old scheme when waking up multiple threads, since we send 908 * only one IPI message per target candidate which may then schedule 909 * multiple threads. Before we could have wound up sending an IPI 910 * message for each thread on the target cpu (!= current cpu) that 911 * needed to be woken up. 912 * 913 * NOTE: Wakeups occuring on remote cpus are asynchronous. This 914 * should be ok since we are passing idents in the IPI rather then 915 * thread pointers. 916 */ 917 if ((domain & PWAKEUP_MYCPU) == 0 && 918 (mask = slpque_cpumasks[id] & gd->gd_other_cpus) != 0) { 919 lwkt_send_ipiq2_mask(mask, _wakeup, ident, 920 domain | PWAKEUP_MYCPU); 921 } 922 #endif 923 done: 924 logtsleep1(wakeup_end); 925 crit_exit(); 926 } 927 928 /* 929 * Wakeup all threads tsleep()ing on the specified ident, on all cpus 930 */ 931 void 932 wakeup(void *ident) 933 { 934 _wakeup(ident, PWAKEUP_ENCODE(0, mycpu->gd_cpuid)); 935 } 936 937 /* 938 * Wakeup one thread tsleep()ing on the specified ident, on any cpu. 939 */ 940 void 941 wakeup_one(void *ident) 942 { 943 /* XXX potentially round-robin the first responding cpu */ 944 _wakeup(ident, PWAKEUP_ENCODE(0, mycpu->gd_cpuid) | PWAKEUP_ONE); 945 } 946 947 /* 948 * Wakeup threads tsleep()ing on the specified ident on the current cpu 949 * only. 950 */ 951 void 952 wakeup_mycpu(void *ident) 953 { 954 _wakeup(ident, PWAKEUP_MYCPU); 955 } 956 957 /* 958 * Wakeup one thread tsleep()ing on the specified ident on the current cpu 959 * only. 960 */ 961 void 962 wakeup_mycpu_one(void *ident) 963 { 964 /* XXX potentially round-robin the first responding cpu */ 965 _wakeup(ident, PWAKEUP_MYCPU|PWAKEUP_ONE); 966 } 967 968 /* 969 * Wakeup all thread tsleep()ing on the specified ident on the specified cpu 970 * only. 971 */ 972 void 973 wakeup_oncpu(globaldata_t gd, void *ident) 974 { 975 #ifdef SMP 976 if (gd == mycpu) { 977 _wakeup(ident, PWAKEUP_MYCPU); 978 } else { 979 lwkt_send_ipiq2(gd, _wakeup, ident, PWAKEUP_MYCPU); 980 } 981 #else 982 _wakeup(ident, PWAKEUP_MYCPU); 983 #endif 984 } 985 986 /* 987 * Wakeup one thread tsleep()ing on the specified ident on the specified cpu 988 * only. 989 */ 990 void 991 wakeup_oncpu_one(globaldata_t gd, void *ident) 992 { 993 #ifdef SMP 994 if (gd == mycpu) { 995 _wakeup(ident, PWAKEUP_MYCPU | PWAKEUP_ONE); 996 } else { 997 lwkt_send_ipiq2(gd, _wakeup, ident, PWAKEUP_MYCPU | PWAKEUP_ONE); 998 } 999 #else 1000 _wakeup(ident, PWAKEUP_MYCPU | PWAKEUP_ONE); 1001 #endif 1002 } 1003 1004 /* 1005 * Wakeup all threads waiting on the specified ident that slept using 1006 * the specified domain, on all cpus. 1007 */ 1008 void 1009 wakeup_domain(void *ident, int domain) 1010 { 1011 _wakeup(ident, PWAKEUP_ENCODE(domain, mycpu->gd_cpuid)); 1012 } 1013 1014 /* 1015 * Wakeup one thread waiting on the specified ident that slept using 1016 * the specified domain, on any cpu. 1017 */ 1018 void 1019 wakeup_domain_one(void *ident, int domain) 1020 { 1021 /* XXX potentially round-robin the first responding cpu */ 1022 _wakeup(ident, PWAKEUP_ENCODE(domain, mycpu->gd_cpuid) | PWAKEUP_ONE); 1023 } 1024 1025 /* 1026 * setrunnable() 1027 * 1028 * Make a process runnable. The MP lock must be held on call. This only 1029 * has an effect if we are in SSLEEP. We only break out of the 1030 * tsleep if LWP_BREAKTSLEEP is set, otherwise we just fix-up the state. 1031 * 1032 * NOTE: With the MP lock held we can only safely manipulate the process 1033 * structure. We cannot safely manipulate the thread structure. 1034 */ 1035 void 1036 setrunnable(struct lwp *lp) 1037 { 1038 crit_enter(); 1039 ASSERT_MP_LOCK_HELD(curthread); 1040 if (lp->lwp_stat == LSSTOP) 1041 lp->lwp_stat = LSSLEEP; 1042 if (lp->lwp_stat == LSSLEEP && (lp->lwp_flag & LWP_BREAKTSLEEP)) 1043 _tsleep_wakeup(lp->lwp_thread); 1044 crit_exit(); 1045 } 1046 1047 /* 1048 * The process is stopped due to some condition, usually because p_stat is 1049 * set to SSTOP, but also possibly due to being traced. 1050 * 1051 * NOTE! If the caller sets SSTOP, the caller must also clear P_WAITED 1052 * because the parent may check the child's status before the child actually 1053 * gets to this routine. 1054 * 1055 * This routine is called with the current lwp only, typically just 1056 * before returning to userland. 1057 * 1058 * Setting LWP_BREAKTSLEEP before entering the tsleep will cause a passive 1059 * SIGCONT to break out of the tsleep. 1060 */ 1061 void 1062 tstop(void) 1063 { 1064 struct lwp *lp = curthread->td_lwp; 1065 struct proc *p = lp->lwp_proc; 1066 1067 crit_enter(); 1068 /* 1069 * If LWP_WSTOP is set, we were sleeping 1070 * while our process was stopped. At this point 1071 * we were already counted as stopped. 1072 */ 1073 if ((lp->lwp_flag & LWP_WSTOP) == 0) { 1074 /* 1075 * If we're the last thread to stop, signal 1076 * our parent. 1077 */ 1078 p->p_nstopped++; 1079 lp->lwp_flag |= LWP_WSTOP; 1080 wakeup(&p->p_nstopped); 1081 if (p->p_nstopped == p->p_nthreads) { 1082 p->p_flag &= ~P_WAITED; 1083 wakeup(p->p_pptr); 1084 if ((p->p_pptr->p_sigacts->ps_flag & PS_NOCLDSTOP) == 0) 1085 ksignal(p->p_pptr, SIGCHLD); 1086 } 1087 } 1088 while (p->p_stat == SSTOP) { 1089 lp->lwp_flag |= LWP_BREAKTSLEEP; 1090 lp->lwp_stat = LSSTOP; 1091 tsleep(p, 0, "stop", 0); 1092 } 1093 p->p_nstopped--; 1094 lp->lwp_flag &= ~LWP_WSTOP; 1095 crit_exit(); 1096 } 1097 1098 /* 1099 * Yield / synchronous reschedule. This is a bit tricky because the trap 1100 * code might have set a lazy release on the switch function. Setting 1101 * P_PASSIVE_ACQ will ensure that the lazy release executes when we call 1102 * switch, and that we are given a greater chance of affinity with our 1103 * current cpu. 1104 * 1105 * We call lwkt_setpri_self() to rotate our thread to the end of the lwkt 1106 * run queue. lwkt_switch() will also execute any assigned passive release 1107 * (which usually calls release_curproc()), allowing a same/higher priority 1108 * process to be designated as the current process. 1109 * 1110 * While it is possible for a lower priority process to be designated, 1111 * it's call to lwkt_maybe_switch() in acquire_curproc() will likely 1112 * round-robin back to us and we will be able to re-acquire the current 1113 * process designation. 1114 * 1115 * MPSAFE 1116 */ 1117 void 1118 uio_yield(void) 1119 { 1120 struct thread *td = curthread; 1121 struct proc *p = td->td_proc; 1122 1123 lwkt_setpri_self(td->td_pri & TDPRI_MASK); 1124 if (p) { 1125 p->p_flag |= P_PASSIVE_ACQ; 1126 lwkt_switch(); 1127 p->p_flag &= ~P_PASSIVE_ACQ; 1128 } else { 1129 lwkt_switch(); 1130 } 1131 } 1132 1133 /* 1134 * Compute a tenex style load average of a quantity on 1135 * 1, 5 and 15 minute intervals. 1136 */ 1137 static int loadav_count_runnable(struct lwp *p, void *data); 1138 1139 static void 1140 loadav(void *arg) 1141 { 1142 struct loadavg *avg; 1143 int i, nrun; 1144 1145 nrun = 0; 1146 alllwp_scan(loadav_count_runnable, &nrun); 1147 avg = &averunnable; 1148 for (i = 0; i < 3; i++) { 1149 avg->ldavg[i] = (cexp[i] * avg->ldavg[i] + 1150 nrun * FSCALE * (FSCALE - cexp[i])) >> FSHIFT; 1151 } 1152 1153 /* 1154 * Schedule the next update to occur after 5 seconds, but add a 1155 * random variation to avoid synchronisation with processes that 1156 * run at regular intervals. 1157 */ 1158 callout_reset(&loadav_callout, hz * 4 + (int)(krandom() % (hz * 2 + 1)), 1159 loadav, NULL); 1160 } 1161 1162 static int 1163 loadav_count_runnable(struct lwp *lp, void *data) 1164 { 1165 int *nrunp = data; 1166 thread_t td; 1167 1168 switch (lp->lwp_stat) { 1169 case LSRUN: 1170 if ((td = lp->lwp_thread) == NULL) 1171 break; 1172 if (td->td_flags & TDF_BLOCKED) 1173 break; 1174 ++*nrunp; 1175 break; 1176 default: 1177 break; 1178 } 1179 return(0); 1180 } 1181 1182 /* ARGSUSED */ 1183 static void 1184 sched_setup(void *dummy) 1185 { 1186 callout_init(&loadav_callout); 1187 callout_init(&schedcpu_callout); 1188 1189 /* Kick off timeout driven events by calling first time. */ 1190 schedcpu(NULL); 1191 loadav(NULL); 1192 } 1193 1194