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 1.86 2007/06/08 02:02:27 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/signal2.h> 51 #include <sys/resourcevar.h> 52 #include <sys/vmmeter.h> 53 #include <sys/sysctl.h> 54 #include <sys/lock.h> 55 #ifdef KTRACE 56 #include <sys/uio.h> 57 #include <sys/ktrace.h> 58 #endif 59 #include <sys/xwait.h> 60 #include <sys/ktr.h> 61 62 #include <sys/thread2.h> 63 #include <sys/spinlock2.h> 64 65 #include <machine/cpu.h> 66 #include <machine/smp.h> 67 68 TAILQ_HEAD(tslpque, thread); 69 70 static void sched_setup (void *dummy); 71 SYSINIT(sched_setup, SI_SUB_KICK_SCHEDULER, SI_ORDER_FIRST, sched_setup, NULL) 72 73 int hogticks; 74 int lbolt; 75 int lbolt_syncer; 76 int sched_quantum; /* Roundrobin scheduling quantum in ticks. */ 77 int ncpus; 78 int ncpus2, ncpus2_shift, ncpus2_mask; 79 int ncpus_fit, ncpus_fit_mask; 80 int safepri; 81 int tsleep_now_works; 82 83 static struct callout loadav_callout; 84 static struct callout schedcpu_callout; 85 MALLOC_DEFINE(M_TSLEEP, "tslpque", "tsleep queues"); 86 87 #if !defined(KTR_TSLEEP) 88 #define KTR_TSLEEP KTR_ALL 89 #endif 90 KTR_INFO_MASTER(tsleep); 91 KTR_INFO(KTR_TSLEEP, tsleep, tsleep_beg, 0, "tsleep enter %p", sizeof(void *)); 92 KTR_INFO(KTR_TSLEEP, tsleep, tsleep_end, 1, "tsleep exit", 0); 93 KTR_INFO(KTR_TSLEEP, tsleep, wakeup_beg, 2, "wakeup enter %p", sizeof(void *)); 94 KTR_INFO(KTR_TSLEEP, tsleep, wakeup_end, 3, "wakeup exit", 0); 95 96 #define logtsleep1(name) KTR_LOG(tsleep_ ## name) 97 #define logtsleep2(name, val) KTR_LOG(tsleep_ ## name, val) 98 99 struct loadavg averunnable = 100 { {0, 0, 0}, FSCALE }; /* load average, of runnable procs */ 101 /* 102 * Constants for averages over 1, 5, and 15 minutes 103 * when sampling at 5 second intervals. 104 */ 105 static fixpt_t cexp[3] = { 106 0.9200444146293232 * FSCALE, /* exp(-1/12) */ 107 0.9834714538216174 * FSCALE, /* exp(-1/60) */ 108 0.9944598480048967 * FSCALE, /* exp(-1/180) */ 109 }; 110 111 static void endtsleep (void *); 112 static void unsleep_and_wakeup_thread(struct thread *td); 113 static void loadav (void *arg); 114 static void schedcpu (void *arg); 115 116 /* 117 * Adjust the scheduler quantum. The quantum is specified in microseconds. 118 * Note that 'tick' is in microseconds per tick. 119 */ 120 static int 121 sysctl_kern_quantum(SYSCTL_HANDLER_ARGS) 122 { 123 int error, new_val; 124 125 new_val = sched_quantum * tick; 126 error = sysctl_handle_int(oidp, &new_val, 0, req); 127 if (error != 0 || req->newptr == NULL) 128 return (error); 129 if (new_val < tick) 130 return (EINVAL); 131 sched_quantum = new_val / tick; 132 hogticks = 2 * sched_quantum; 133 return (0); 134 } 135 136 SYSCTL_PROC(_kern, OID_AUTO, quantum, CTLTYPE_INT|CTLFLAG_RW, 137 0, sizeof sched_quantum, sysctl_kern_quantum, "I", ""); 138 139 /* 140 * If `ccpu' is not equal to `exp(-1/20)' and you still want to use the 141 * faster/more-accurate formula, you'll have to estimate CCPU_SHIFT below 142 * and possibly adjust FSHIFT in "param.h" so that (FSHIFT >= CCPU_SHIFT). 143 * 144 * To estimate CCPU_SHIFT for exp(-1/20), the following formula was used: 145 * 1 - exp(-1/20) ~= 0.0487 ~= 0.0488 == 1 (fixed pt, *11* bits). 146 * 147 * If you don't want to bother with the faster/more-accurate formula, you 148 * can set CCPU_SHIFT to (FSHIFT + 1) which will use a slower/less-accurate 149 * (more general) method of calculating the %age of CPU used by a process. 150 * 151 * decay 95% of `lwp_pctcpu' in 60 seconds; see CCPU_SHIFT before changing 152 */ 153 #define CCPU_SHIFT 11 154 155 static fixpt_t ccpu = 0.95122942450071400909 * FSCALE; /* exp(-1/20) */ 156 SYSCTL_INT(_kern, OID_AUTO, ccpu, CTLFLAG_RD, &ccpu, 0, ""); 157 158 /* 159 * kernel uses `FSCALE', userland (SHOULD) use kern.fscale 160 */ 161 int fscale __unused = FSCALE; /* exported to systat */ 162 SYSCTL_INT(_kern, OID_AUTO, fscale, CTLFLAG_RD, 0, FSCALE, ""); 163 164 /* 165 * Recompute process priorities, once a second. 166 * 167 * Since the userland schedulers are typically event oriented, if the 168 * estcpu calculation at wakeup() time is not sufficient to make a 169 * process runnable relative to other processes in the system we have 170 * a 1-second recalc to help out. 171 * 172 * This code also allows us to store sysclock_t data in the process structure 173 * without fear of an overrun, since sysclock_t are guarenteed to hold 174 * several seconds worth of count. 175 * 176 * WARNING! callouts can preempt normal threads. However, they will not 177 * preempt a thread holding a spinlock so we *can* safely use spinlocks. 178 */ 179 static int schedcpu_stats(struct proc *p, void *data __unused); 180 static int schedcpu_resource(struct proc *p, void *data __unused); 181 182 static void 183 schedcpu(void *arg) 184 { 185 allproc_scan(schedcpu_stats, NULL); 186 allproc_scan(schedcpu_resource, NULL); 187 wakeup((caddr_t)&lbolt); 188 wakeup((caddr_t)&lbolt_syncer); 189 callout_reset(&schedcpu_callout, hz, schedcpu, NULL); 190 } 191 192 /* 193 * General process statistics once a second 194 */ 195 static int 196 schedcpu_stats(struct proc *p, void *data __unused) 197 { 198 struct lwp *lp; 199 200 crit_enter(); 201 p->p_swtime++; 202 FOREACH_LWP_IN_PROC(lp, p) { 203 if (lp->lwp_stat == LSSLEEP) 204 lp->lwp_slptime++; 205 206 /* 207 * Only recalculate processes that are active or have slept 208 * less then 2 seconds. The schedulers understand this. 209 */ 210 if (lp->lwp_slptime <= 1) { 211 p->p_usched->recalculate(lp); 212 } else { 213 lp->lwp_pctcpu = (lp->lwp_pctcpu * ccpu) >> FSHIFT; 214 } 215 } 216 crit_exit(); 217 return(0); 218 } 219 220 /* 221 * Resource checks. XXX break out since ksignal/killproc can block, 222 * limiting us to one process killed per second. There is probably 223 * a better way. 224 */ 225 static int 226 schedcpu_resource(struct proc *p, void *data __unused) 227 { 228 u_int64_t ttime; 229 struct lwp *lp; 230 231 crit_enter(); 232 if (p->p_stat == SIDL || 233 p->p_stat == SZOMB || 234 p->p_limit == NULL 235 ) { 236 crit_exit(); 237 return(0); 238 } 239 240 ttime = 0; 241 FOREACH_LWP_IN_PROC(lp, p) { 242 ttime += lp->lwp_thread->td_sticks; 243 ttime += lp->lwp_thread->td_uticks; 244 } 245 246 switch(plimit_testcpulimit(p->p_limit, ttime)) { 247 case PLIMIT_TESTCPU_KILL: 248 killproc(p, "exceeded maximum CPU limit"); 249 break; 250 case PLIMIT_TESTCPU_XCPU: 251 if ((p->p_flag & P_XCPU) == 0) { 252 p->p_flag |= P_XCPU; 253 ksignal(p, SIGXCPU); 254 } 255 break; 256 default: 257 break; 258 } 259 crit_exit(); 260 return(0); 261 } 262 263 /* 264 * This is only used by ps. Generate a cpu percentage use over 265 * a period of one second. 266 * 267 * MPSAFE 268 */ 269 void 270 updatepcpu(struct lwp *lp, int cpticks, int ttlticks) 271 { 272 fixpt_t acc; 273 int remticks; 274 275 acc = (cpticks << FSHIFT) / ttlticks; 276 if (ttlticks >= ESTCPUFREQ) { 277 lp->lwp_pctcpu = acc; 278 } else { 279 remticks = ESTCPUFREQ - ttlticks; 280 lp->lwp_pctcpu = (acc * ttlticks + lp->lwp_pctcpu * remticks) / 281 ESTCPUFREQ; 282 } 283 } 284 285 /* 286 * tsleep/wakeup hash table parameters. Try to find the sweet spot for 287 * like addresses being slept on. 288 */ 289 #define TABLESIZE 1024 290 #define LOOKUP(x) (((intptr_t)(x) >> 6) & (TABLESIZE - 1)) 291 292 static cpumask_t slpque_cpumasks[TABLESIZE]; 293 294 /* 295 * General scheduler initialization. We force a reschedule 25 times 296 * a second by default. Note that cpu0 is initialized in early boot and 297 * cannot make any high level calls. 298 * 299 * Each cpu has its own sleep queue. 300 */ 301 void 302 sleep_gdinit(globaldata_t gd) 303 { 304 static struct tslpque slpque_cpu0[TABLESIZE]; 305 int i; 306 307 if (gd->gd_cpuid == 0) { 308 sched_quantum = (hz + 24) / 25; 309 hogticks = 2 * sched_quantum; 310 311 gd->gd_tsleep_hash = slpque_cpu0; 312 } else { 313 gd->gd_tsleep_hash = kmalloc(sizeof(slpque_cpu0), 314 M_TSLEEP, M_WAITOK | M_ZERO); 315 } 316 for (i = 0; i < TABLESIZE; ++i) 317 TAILQ_INIT(&gd->gd_tsleep_hash[i]); 318 } 319 320 /* 321 * General sleep call. Suspends the current process until a wakeup is 322 * performed on the specified identifier. The process will then be made 323 * runnable with the specified priority. Sleeps at most timo/hz seconds 324 * (0 means no timeout). If flags includes PCATCH flag, signals are checked 325 * before and after sleeping, else signals are not checked. Returns 0 if 326 * awakened, EWOULDBLOCK if the timeout expires. If PCATCH is set and a 327 * signal needs to be delivered, ERESTART is returned if the current system 328 * call should be restarted if possible, and EINTR is returned if the system 329 * call should be interrupted by the signal (return EINTR). 330 * 331 * Note that if we are a process, we release_curproc() before messing with 332 * the LWKT scheduler. 333 * 334 * During autoconfiguration or after a panic, a sleep will simply 335 * lower the priority briefly to allow interrupts, then return. 336 */ 337 int 338 tsleep(void *ident, int flags, const char *wmesg, int timo) 339 { 340 struct thread *td = curthread; 341 struct lwp *lp = td->td_lwp; 342 struct proc *p = td->td_proc; /* may be NULL */ 343 globaldata_t gd; 344 int sig; 345 int catch; 346 int id; 347 int error; 348 int oldpri; 349 struct callout thandle; 350 351 /* 352 * NOTE: removed KTRPOINT, it could cause races due to blocking 353 * even in stable. Just scrap it for now. 354 */ 355 if (tsleep_now_works == 0 || panicstr) { 356 /* 357 * After a panic, or before we actually have an operational 358 * softclock, just give interrupts a chance, then just return; 359 * 360 * don't run any other procs or panic below, 361 * in case this is the idle process and already asleep. 362 */ 363 splz(); 364 oldpri = td->td_pri & TDPRI_MASK; 365 lwkt_setpri_self(safepri); 366 lwkt_switch(); 367 lwkt_setpri_self(oldpri); 368 return (0); 369 } 370 logtsleep2(tsleep_beg, ident); 371 gd = td->td_gd; 372 KKASSERT(td != &gd->gd_idlethread); /* you must be kidding! */ 373 374 /* 375 * NOTE: all of this occurs on the current cpu, including any 376 * callout-based wakeups, so a critical section is a sufficient 377 * interlock. 378 * 379 * The entire sequence through to where we actually sleep must 380 * run without breaking the critical section. 381 */ 382 id = LOOKUP(ident); 383 catch = flags & PCATCH; 384 error = 0; 385 sig = 0; 386 387 crit_enter_quick(td); 388 389 KASSERT(ident != NULL, ("tsleep: no ident")); 390 KASSERT(lp == NULL || 391 lp->lwp_stat == LSRUN || /* Obvious */ 392 lp->lwp_stat == LSSTOP, /* Set in tstop */ 393 ("tsleep %p %s %d", 394 ident, wmesg, lp->lwp_stat)); 395 396 /* 397 * Setup for the current process (if this is a process). 398 */ 399 if (lp) { 400 if (catch) { 401 /* 402 * Early termination if PCATCH was set and a 403 * signal is pending, interlocked with the 404 * critical section. 405 * 406 * Early termination only occurs when tsleep() is 407 * entered while in a normal LSRUN state. 408 */ 409 if ((sig = CURSIG(lp)) != 0) 410 goto resume; 411 412 /* 413 * Early termination if PCATCH was set and a 414 * mailbox signal was possibly delivered prior to 415 * the system call even being made, in order to 416 * allow the user to interlock without having to 417 * make additional system calls. 418 */ 419 if (p->p_flag & P_MAILBOX) 420 goto resume; 421 422 /* 423 * Causes ksignal to wake us up when. 424 */ 425 lp->lwp_flag |= LWP_SINTR; 426 } 427 428 /* 429 * Make sure the current process has been untangled from 430 * the userland scheduler and initialize slptime to start 431 * counting. 432 */ 433 if (flags & PNORESCHED) 434 td->td_flags |= TDF_NORESCHED; 435 p->p_usched->release_curproc(lp); 436 lp->lwp_slptime = 0; 437 } 438 439 /* 440 * Move our thread to the correct queue and setup our wchan, etc. 441 */ 442 lwkt_deschedule_self(td); 443 td->td_flags |= TDF_TSLEEPQ; 444 TAILQ_INSERT_TAIL(&gd->gd_tsleep_hash[id], td, td_threadq); 445 atomic_set_int(&slpque_cpumasks[id], gd->gd_cpumask); 446 447 td->td_wchan = ident; 448 td->td_wmesg = wmesg; 449 td->td_wdomain = flags & PDOMAIN_MASK; 450 451 /* 452 * Setup the timeout, if any 453 */ 454 if (timo) { 455 callout_init(&thandle); 456 callout_reset(&thandle, timo, endtsleep, td); 457 } 458 459 /* 460 * Beddy bye bye. 461 */ 462 if (lp) { 463 /* 464 * Ok, we are sleeping. Place us in the SSLEEP state. 465 */ 466 KKASSERT((lp->lwp_flag & LWP_ONRUNQ) == 0); 467 /* 468 * tstop() sets LSSTOP, so don't fiddle with that. 469 */ 470 if (lp->lwp_stat != LSSTOP) 471 lp->lwp_stat = LSSLEEP; 472 lp->lwp_ru.ru_nvcsw++; 473 lwkt_switch(); 474 475 /* 476 * And when we are woken up, put us back in LSRUN. If we 477 * slept for over a second, recalculate our estcpu. 478 */ 479 lp->lwp_stat = LSRUN; 480 if (lp->lwp_slptime) 481 p->p_usched->recalculate(lp); 482 lp->lwp_slptime = 0; 483 } else { 484 lwkt_switch(); 485 } 486 487 /* 488 * Make sure we haven't switched cpus while we were asleep. It's 489 * not supposed to happen. Cleanup our temporary flags. 490 */ 491 KKASSERT(gd == td->td_gd); 492 td->td_flags &= ~TDF_NORESCHED; 493 494 /* 495 * Cleanup the timeout. 496 */ 497 if (timo) { 498 if (td->td_flags & TDF_TIMEOUT) { 499 td->td_flags &= ~TDF_TIMEOUT; 500 error = EWOULDBLOCK; 501 } else { 502 callout_stop(&thandle); 503 } 504 } 505 506 /* 507 * Since td_threadq is used both for our run queue AND for the 508 * tsleep hash queue, we can't still be on it at this point because 509 * we've gotten cpu back. 510 */ 511 KASSERT((td->td_flags & TDF_TSLEEPQ) == 0, ("tsleep: impossible thread flags %08x", td->td_flags)); 512 td->td_wchan = NULL; 513 td->td_wmesg = NULL; 514 td->td_wdomain = 0; 515 516 /* 517 * Figure out the correct error return. If interrupted by a 518 * signal we want to return EINTR or ERESTART. 519 * 520 * If P_MAILBOX is set no automatic system call restart occurs 521 * and we return EINTR. P_MAILBOX is meant to be used as an 522 * interlock, the user must poll it prior to any system call 523 * that it wishes to interlock a mailbox signal against since 524 * the flag is cleared on *any* system call that sleeps. 525 */ 526 resume: 527 if (p) { 528 if (catch && error == 0) { 529 if ((p->p_flag & P_MAILBOX) && sig == 0) { 530 error = EINTR; 531 } else if (sig != 0 || (sig = CURSIG(lp))) { 532 if (SIGISMEMBER(p->p_sigacts->ps_sigintr, sig)) 533 error = EINTR; 534 else 535 error = ERESTART; 536 } 537 } 538 lp->lwp_flag &= ~(LWP_BREAKTSLEEP | LWP_SINTR); 539 p->p_flag &= ~P_MAILBOX; 540 } 541 logtsleep1(tsleep_end); 542 crit_exit_quick(td); 543 return (error); 544 } 545 546 /* 547 * This is a dandy function that allows us to interlock tsleep/wakeup 548 * operations with unspecified upper level locks, such as lockmgr locks, 549 * simply by holding a critical section. The sequence is: 550 * 551 * (enter critical section) 552 * (acquire upper level lock) 553 * tsleep_interlock(blah) 554 * (release upper level lock) 555 * tsleep(blah, ...) 556 * (exit critical section) 557 * 558 * Basically this function sets our cpumask for the ident which informs 559 * other cpus that our cpu 'might' be waiting (or about to wait on) the 560 * hash index related to the ident. The critical section prevents another 561 * cpu's wakeup() from being processed on our cpu until we are actually 562 * able to enter the tsleep(). Thus, no race occurs between our attempt 563 * to release a resource and sleep, and another cpu's attempt to acquire 564 * a resource and call wakeup. 565 * 566 * There isn't much of a point to this function unless you call it while 567 * holding a critical section. 568 */ 569 static __inline void 570 _tsleep_interlock(globaldata_t gd, void *ident) 571 { 572 int id = LOOKUP(ident); 573 574 atomic_set_int(&slpque_cpumasks[id], gd->gd_cpumask); 575 } 576 577 void 578 tsleep_interlock(void *ident) 579 { 580 _tsleep_interlock(mycpu, ident); 581 } 582 583 /* 584 * Interlocked spinlock sleep. An exclusively held spinlock must 585 * be passed to msleep(). The function will atomically release the 586 * spinlock and tsleep on the ident, then reacquire the spinlock and 587 * return. 588 * 589 * This routine is fairly important along the critical path, so optimize it 590 * heavily. 591 */ 592 int 593 msleep(void *ident, struct spinlock *spin, int flags, 594 const char *wmesg, int timo) 595 { 596 globaldata_t gd = mycpu; 597 int error; 598 599 crit_enter_gd(gd); 600 _tsleep_interlock(gd, ident); 601 spin_unlock_wr_quick(gd, spin); 602 error = tsleep(ident, flags, wmesg, timo); 603 spin_lock_wr_quick(gd, spin); 604 crit_exit_gd(gd); 605 606 return (error); 607 } 608 609 /* 610 * Directly block on the LWKT thread by descheduling it. This 611 * is much faster then tsleep(), but the only legal way to wake 612 * us up is to directly schedule the thread. 613 * 614 * Setting TDF_SINTR will cause new signals to directly schedule us. 615 * 616 * This routine is typically called while in a critical section. 617 */ 618 int 619 lwkt_sleep(const char *wmesg, int flags) 620 { 621 thread_t td = curthread; 622 int sig; 623 624 if ((flags & PCATCH) == 0 || td->td_lwp == NULL) { 625 td->td_flags |= TDF_BLOCKED; 626 td->td_wmesg = wmesg; 627 lwkt_deschedule_self(td); 628 lwkt_switch(); 629 td->td_wmesg = NULL; 630 td->td_flags &= ~TDF_BLOCKED; 631 return(0); 632 } 633 if ((sig = CURSIG(td->td_lwp)) != 0) { 634 if (SIGISMEMBER(td->td_proc->p_sigacts->ps_sigintr, sig)) 635 return(EINTR); 636 else 637 return(ERESTART); 638 639 } 640 td->td_flags |= TDF_BLOCKED | TDF_SINTR; 641 td->td_wmesg = wmesg; 642 lwkt_deschedule_self(td); 643 lwkt_switch(); 644 td->td_flags &= ~(TDF_BLOCKED | TDF_SINTR); 645 td->td_wmesg = NULL; 646 return(0); 647 } 648 649 /* 650 * Implement the timeout for tsleep. 651 * 652 * We set LWP_BREAKTSLEEP to indicate that an event has occured, but 653 * we only call setrunnable if the process is not stopped. 654 * 655 * This type of callout timeout is scheduled on the same cpu the process 656 * is sleeping on. Also, at the moment, the MP lock is held. 657 */ 658 static void 659 endtsleep(void *arg) 660 { 661 thread_t td = arg; 662 struct lwp *lp; 663 664 ASSERT_MP_LOCK_HELD(curthread); 665 crit_enter(); 666 667 /* 668 * cpu interlock. Thread flags are only manipulated on 669 * the cpu owning the thread. proc flags are only manipulated 670 * by the older of the MP lock. We have both. 671 */ 672 if (td->td_flags & TDF_TSLEEPQ) { 673 td->td_flags |= TDF_TIMEOUT; 674 675 if ((lp = td->td_lwp) != NULL) { 676 lp->lwp_flag |= LWP_BREAKTSLEEP; 677 if (lp->lwp_proc->p_stat != SSTOP) 678 setrunnable(lp); 679 } else { 680 unsleep_and_wakeup_thread(td); 681 } 682 } 683 crit_exit(); 684 } 685 686 /* 687 * Unsleep and wakeup a thread. This function runs without the MP lock 688 * which means that it can only manipulate thread state on the owning cpu, 689 * and cannot touch the process state at all. 690 */ 691 static 692 void 693 unsleep_and_wakeup_thread(struct thread *td) 694 { 695 globaldata_t gd = mycpu; 696 int id; 697 698 #ifdef SMP 699 if (td->td_gd != gd) { 700 lwkt_send_ipiq(td->td_gd, (ipifunc1_t)unsleep_and_wakeup_thread, td); 701 return; 702 } 703 #endif 704 crit_enter(); 705 if (td->td_flags & TDF_TSLEEPQ) { 706 td->td_flags &= ~TDF_TSLEEPQ; 707 id = LOOKUP(td->td_wchan); 708 TAILQ_REMOVE(&gd->gd_tsleep_hash[id], td, td_threadq); 709 if (TAILQ_FIRST(&gd->gd_tsleep_hash[id]) == NULL) 710 atomic_clear_int(&slpque_cpumasks[id], gd->gd_cpumask); 711 lwkt_schedule(td); 712 } 713 crit_exit(); 714 } 715 716 /* 717 * Make all processes sleeping on the specified identifier runnable. 718 * count may be zero or one only. 719 * 720 * The domain encodes the sleep/wakeup domain AND the first cpu to check 721 * (which is always the current cpu). As we iterate across cpus 722 * 723 * This call may run without the MP lock held. We can only manipulate thread 724 * state on the cpu owning the thread. We CANNOT manipulate process state 725 * at all. 726 */ 727 static void 728 _wakeup(void *ident, int domain) 729 { 730 struct tslpque *qp; 731 struct thread *td; 732 struct thread *ntd; 733 globaldata_t gd; 734 #ifdef SMP 735 cpumask_t mask; 736 cpumask_t tmask; 737 int startcpu; 738 int nextcpu; 739 #endif 740 int id; 741 742 crit_enter(); 743 logtsleep2(wakeup_beg, ident); 744 gd = mycpu; 745 id = LOOKUP(ident); 746 qp = &gd->gd_tsleep_hash[id]; 747 restart: 748 for (td = TAILQ_FIRST(qp); td != NULL; td = ntd) { 749 ntd = TAILQ_NEXT(td, td_threadq); 750 if (td->td_wchan == ident && 751 td->td_wdomain == (domain & PDOMAIN_MASK) 752 ) { 753 KKASSERT(td->td_flags & TDF_TSLEEPQ); 754 td->td_flags &= ~TDF_TSLEEPQ; 755 TAILQ_REMOVE(qp, td, td_threadq); 756 if (TAILQ_FIRST(qp) == NULL) { 757 atomic_clear_int(&slpque_cpumasks[id], 758 gd->gd_cpumask); 759 } 760 lwkt_schedule(td); 761 if (domain & PWAKEUP_ONE) 762 goto done; 763 goto restart; 764 } 765 } 766 767 #ifdef SMP 768 /* 769 * We finished checking the current cpu but there still may be 770 * more work to do. Either wakeup_one was requested and no matching 771 * thread was found, or a normal wakeup was requested and we have 772 * to continue checking cpus. 773 * 774 * The cpu that started the wakeup sequence is encoded in the domain. 775 * We use this information to determine which cpus still need to be 776 * checked, locate a candidate cpu, and chain the wakeup 777 * asynchronously with an IPI message. 778 * 779 * It should be noted that this scheme is actually less expensive then 780 * the old scheme when waking up multiple threads, since we send 781 * only one IPI message per target candidate which may then schedule 782 * multiple threads. Before we could have wound up sending an IPI 783 * message for each thread on the target cpu (!= current cpu) that 784 * needed to be woken up. 785 * 786 * NOTE: Wakeups occuring on remote cpus are asynchronous. This 787 * should be ok since we are passing idents in the IPI rather then 788 * thread pointers. 789 */ 790 if ((domain & PWAKEUP_MYCPU) == 0 && 791 (mask = slpque_cpumasks[id]) != 0 792 ) { 793 /* 794 * Look for a cpu that might have work to do. Mask out cpus 795 * which have already been processed. 796 * 797 * 31xxxxxxxxxxxxxxxxxxxxxxxxxxxxx0 798 * ^ ^ ^ 799 * start currentcpu start 800 * case2 case1 801 * * * * 802 * 11111111111111110000000000000111 case1 803 * 00000000111111110000000000000000 case2 804 * 805 * case1: We started at start_case1 and processed through 806 * to the current cpu. We have to check any bits 807 * after the current cpu, then check bits before 808 * the starting cpu. 809 * 810 * case2: We have already checked all the bits from 811 * start_case2 to the end, and from 0 to the current 812 * cpu. We just have the bits from the current cpu 813 * to start_case2 left to check. 814 */ 815 startcpu = PWAKEUP_DECODE(domain); 816 if (gd->gd_cpuid >= startcpu) { 817 /* 818 * CASE1 819 */ 820 tmask = mask & ~((gd->gd_cpumask << 1) - 1); 821 if (mask & tmask) { 822 nextcpu = bsfl(mask & tmask); 823 lwkt_send_ipiq2(globaldata_find(nextcpu), 824 _wakeup, ident, domain); 825 } else { 826 tmask = (1 << startcpu) - 1; 827 if (mask & tmask) { 828 nextcpu = bsfl(mask & tmask); 829 lwkt_send_ipiq2( 830 globaldata_find(nextcpu), 831 _wakeup, ident, domain); 832 } 833 } 834 } else { 835 /* 836 * CASE2 837 */ 838 tmask = ~((gd->gd_cpumask << 1) - 1) & 839 ((1 << startcpu) - 1); 840 if (mask & tmask) { 841 nextcpu = bsfl(mask & tmask); 842 lwkt_send_ipiq2(globaldata_find(nextcpu), 843 _wakeup, ident, domain); 844 } 845 } 846 } 847 #endif 848 done: 849 logtsleep1(wakeup_end); 850 crit_exit(); 851 } 852 853 /* 854 * Wakeup all threads tsleep()ing on the specified ident, on all cpus 855 */ 856 void 857 wakeup(void *ident) 858 { 859 _wakeup(ident, PWAKEUP_ENCODE(0, mycpu->gd_cpuid)); 860 } 861 862 /* 863 * Wakeup one thread tsleep()ing on the specified ident, on any cpu. 864 */ 865 void 866 wakeup_one(void *ident) 867 { 868 /* XXX potentially round-robin the first responding cpu */ 869 _wakeup(ident, PWAKEUP_ENCODE(0, mycpu->gd_cpuid) | PWAKEUP_ONE); 870 } 871 872 /* 873 * Wakeup threads tsleep()ing on the specified ident on the current cpu 874 * only. 875 */ 876 void 877 wakeup_mycpu(void *ident) 878 { 879 _wakeup(ident, PWAKEUP_MYCPU); 880 } 881 882 /* 883 * Wakeup one thread tsleep()ing on the specified ident on the current cpu 884 * only. 885 */ 886 void 887 wakeup_mycpu_one(void *ident) 888 { 889 /* XXX potentially round-robin the first responding cpu */ 890 _wakeup(ident, PWAKEUP_MYCPU|PWAKEUP_ONE); 891 } 892 893 /* 894 * Wakeup all thread tsleep()ing on the specified ident on the specified cpu 895 * only. 896 */ 897 void 898 wakeup_oncpu(globaldata_t gd, void *ident) 899 { 900 #ifdef SMP 901 if (gd == mycpu) { 902 _wakeup(ident, PWAKEUP_MYCPU); 903 } else { 904 lwkt_send_ipiq2(gd, _wakeup, ident, PWAKEUP_MYCPU); 905 } 906 #else 907 _wakeup(ident, PWAKEUP_MYCPU); 908 #endif 909 } 910 911 /* 912 * Wakeup one thread tsleep()ing on the specified ident on the specified cpu 913 * only. 914 */ 915 void 916 wakeup_oncpu_one(globaldata_t gd, void *ident) 917 { 918 #ifdef SMP 919 if (gd == mycpu) { 920 _wakeup(ident, PWAKEUP_MYCPU | PWAKEUP_ONE); 921 } else { 922 lwkt_send_ipiq2(gd, _wakeup, ident, PWAKEUP_MYCPU | PWAKEUP_ONE); 923 } 924 #else 925 _wakeup(ident, PWAKEUP_MYCPU | PWAKEUP_ONE); 926 #endif 927 } 928 929 /* 930 * Wakeup all threads waiting on the specified ident that slept using 931 * the specified domain, on all cpus. 932 */ 933 void 934 wakeup_domain(void *ident, int domain) 935 { 936 _wakeup(ident, PWAKEUP_ENCODE(domain, mycpu->gd_cpuid)); 937 } 938 939 /* 940 * Wakeup one thread waiting on the specified ident that slept using 941 * the specified domain, on any cpu. 942 */ 943 void 944 wakeup_domain_one(void *ident, int domain) 945 { 946 /* XXX potentially round-robin the first responding cpu */ 947 _wakeup(ident, PWAKEUP_ENCODE(domain, mycpu->gd_cpuid) | PWAKEUP_ONE); 948 } 949 950 /* 951 * setrunnable() 952 * 953 * Make a process runnable. The MP lock must be held on call. This only 954 * has an effect if we are in SSLEEP. We only break out of the 955 * tsleep if LWP_BREAKTSLEEP is set, otherwise we just fix-up the state. 956 * 957 * NOTE: With the MP lock held we can only safely manipulate the process 958 * structure. We cannot safely manipulate the thread structure. 959 */ 960 void 961 setrunnable(struct lwp *lp) 962 { 963 crit_enter(); 964 ASSERT_MP_LOCK_HELD(curthread); 965 if (lp->lwp_stat == LSSTOP) 966 lp->lwp_stat = LSSLEEP; 967 if (lp->lwp_stat == LSSLEEP && (lp->lwp_flag & LWP_BREAKTSLEEP)) 968 unsleep_and_wakeup_thread(lp->lwp_thread); 969 crit_exit(); 970 } 971 972 /* 973 * The process is stopped due to some condition, usually because p_stat is 974 * set to SSTOP, but also possibly due to being traced. 975 * 976 * NOTE! If the caller sets SSTOP, the caller must also clear P_WAITED 977 * because the parent may check the child's status before the child actually 978 * gets to this routine. 979 * 980 * This routine is called with the current lwp only, typically just 981 * before returning to userland. 982 * 983 * Setting LWP_BREAKTSLEEP before entering the tsleep will cause a passive 984 * SIGCONT to break out of the tsleep. 985 */ 986 void 987 tstop(void) 988 { 989 struct lwp *lp = curthread->td_lwp; 990 struct proc *p = lp->lwp_proc; 991 992 lp->lwp_flag |= LWP_BREAKTSLEEP; 993 lp->lwp_stat = LSSTOP; 994 crit_enter(); 995 /* 996 * If LWP_WSTOP is set, we were sleeping 997 * while our process was stopped. At this point 998 * we were already counted as stopped. 999 */ 1000 if ((lp->lwp_flag & LWP_WSTOP) == 0) { 1001 /* 1002 * If we're the last thread to stop, signal 1003 * our parent. 1004 */ 1005 p->p_nstopped++; 1006 lp->lwp_flag |= LWP_WSTOP; 1007 if (p->p_nstopped == p->p_nthreads) { 1008 p->p_flag &= ~P_WAITED; 1009 wakeup(p->p_pptr); 1010 if ((p->p_pptr->p_sigacts->ps_flag & PS_NOCLDSTOP) == 0) 1011 ksignal(p->p_pptr, SIGCHLD); 1012 } 1013 } 1014 tsleep(lp->lwp_proc, 0, "stop", 0); 1015 p->p_nstopped--; 1016 crit_exit(); 1017 } 1018 1019 /* 1020 * Yield / synchronous reschedule. This is a bit tricky because the trap 1021 * code might have set a lazy release on the switch function. Setting 1022 * P_PASSIVE_ACQ will ensure that the lazy release executes when we call 1023 * switch, and that we are given a greater chance of affinity with our 1024 * current cpu. 1025 * 1026 * We call lwkt_setpri_self() to rotate our thread to the end of the lwkt 1027 * run queue. lwkt_switch() will also execute any assigned passive release 1028 * (which usually calls release_curproc()), allowing a same/higher priority 1029 * process to be designated as the current process. 1030 * 1031 * While it is possible for a lower priority process to be designated, 1032 * it's call to lwkt_maybe_switch() in acquire_curproc() will likely 1033 * round-robin back to us and we will be able to re-acquire the current 1034 * process designation. 1035 */ 1036 void 1037 uio_yield(void) 1038 { 1039 struct thread *td = curthread; 1040 struct proc *p = td->td_proc; 1041 1042 lwkt_setpri_self(td->td_pri & TDPRI_MASK); 1043 if (p) { 1044 p->p_flag |= P_PASSIVE_ACQ; 1045 lwkt_switch(); 1046 p->p_flag &= ~P_PASSIVE_ACQ; 1047 } else { 1048 lwkt_switch(); 1049 } 1050 } 1051 1052 /* 1053 * Compute a tenex style load average of a quantity on 1054 * 1, 5 and 15 minute intervals. 1055 */ 1056 static int loadav_count_runnable(struct lwp *p, void *data); 1057 1058 static void 1059 loadav(void *arg) 1060 { 1061 struct loadavg *avg; 1062 int i, nrun; 1063 1064 nrun = 0; 1065 alllwp_scan(loadav_count_runnable, &nrun); 1066 avg = &averunnable; 1067 for (i = 0; i < 3; i++) { 1068 avg->ldavg[i] = (cexp[i] * avg->ldavg[i] + 1069 nrun * FSCALE * (FSCALE - cexp[i])) >> FSHIFT; 1070 } 1071 1072 /* 1073 * Schedule the next update to occur after 5 seconds, but add a 1074 * random variation to avoid synchronisation with processes that 1075 * run at regular intervals. 1076 */ 1077 callout_reset(&loadav_callout, hz * 4 + (int)(krandom() % (hz * 2 + 1)), 1078 loadav, NULL); 1079 } 1080 1081 static int 1082 loadav_count_runnable(struct lwp *lp, void *data) 1083 { 1084 int *nrunp = data; 1085 thread_t td; 1086 1087 switch (lp->lwp_stat) { 1088 case LSRUN: 1089 if ((td = lp->lwp_thread) == NULL) 1090 break; 1091 if (td->td_flags & TDF_BLOCKED) 1092 break; 1093 ++*nrunp; 1094 break; 1095 default: 1096 break; 1097 } 1098 return(0); 1099 } 1100 1101 /* ARGSUSED */ 1102 static void 1103 sched_setup(void *dummy) 1104 { 1105 callout_init(&loadav_callout); 1106 callout_init(&schedcpu_callout); 1107 1108 /* Kick off timeout driven events by calling first time. */ 1109 schedcpu(NULL); 1110 loadav(NULL); 1111 } 1112 1113