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 1.82 2007/03/12 21:08:15 corecode 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 safepri; 80 81 static struct callout loadav_callout; 82 static struct callout schedcpu_callout; 83 MALLOC_DEFINE(M_TSLEEP, "tslpque", "tsleep queues"); 84 85 #if !defined(KTR_TSLEEP) 86 #define KTR_TSLEEP KTR_ALL 87 #endif 88 KTR_INFO_MASTER(tsleep); 89 KTR_INFO(KTR_TSLEEP, tsleep, tsleep_beg, 0, "tsleep enter", 0); 90 KTR_INFO(KTR_TSLEEP, tsleep, tsleep_end, 0, "tsleep exit", 0); 91 KTR_INFO(KTR_TSLEEP, tsleep, wakeup_beg, 0, "wakeup enter", 0); 92 KTR_INFO(KTR_TSLEEP, tsleep, wakeup_end, 0, "wakeup exit", 0); 93 #define logtsleep(name) KTR_LOG(tsleep_ ## name) 94 95 struct loadavg averunnable = 96 { {0, 0, 0}, FSCALE }; /* load average, of runnable procs */ 97 /* 98 * Constants for averages over 1, 5, and 15 minutes 99 * when sampling at 5 second intervals. 100 */ 101 static fixpt_t cexp[3] = { 102 0.9200444146293232 * FSCALE, /* exp(-1/12) */ 103 0.9834714538216174 * FSCALE, /* exp(-1/60) */ 104 0.9944598480048967 * FSCALE, /* exp(-1/180) */ 105 }; 106 107 static void endtsleep (void *); 108 static void unsleep_and_wakeup_thread(struct thread *td); 109 static void loadav (void *arg); 110 static void schedcpu (void *arg); 111 112 /* 113 * Adjust the scheduler quantum. The quantum is specified in microseconds. 114 * Note that 'tick' is in microseconds per tick. 115 */ 116 static int 117 sysctl_kern_quantum(SYSCTL_HANDLER_ARGS) 118 { 119 int error, new_val; 120 121 new_val = sched_quantum * tick; 122 error = sysctl_handle_int(oidp, &new_val, 0, req); 123 if (error != 0 || req->newptr == NULL) 124 return (error); 125 if (new_val < tick) 126 return (EINVAL); 127 sched_quantum = new_val / tick; 128 hogticks = 2 * sched_quantum; 129 return (0); 130 } 131 132 SYSCTL_PROC(_kern, OID_AUTO, quantum, CTLTYPE_INT|CTLFLAG_RW, 133 0, sizeof sched_quantum, sysctl_kern_quantum, "I", ""); 134 135 /* 136 * If `ccpu' is not equal to `exp(-1/20)' and you still want to use the 137 * faster/more-accurate formula, you'll have to estimate CCPU_SHIFT below 138 * and possibly adjust FSHIFT in "param.h" so that (FSHIFT >= CCPU_SHIFT). 139 * 140 * To estimate CCPU_SHIFT for exp(-1/20), the following formula was used: 141 * 1 - exp(-1/20) ~= 0.0487 ~= 0.0488 == 1 (fixed pt, *11* bits). 142 * 143 * If you don't want to bother with the faster/more-accurate formula, you 144 * can set CCPU_SHIFT to (FSHIFT + 1) which will use a slower/less-accurate 145 * (more general) method of calculating the %age of CPU used by a process. 146 * 147 * decay 95% of `lwp_pctcpu' in 60 seconds; see CCPU_SHIFT before changing 148 */ 149 #define CCPU_SHIFT 11 150 151 static fixpt_t ccpu = 0.95122942450071400909 * FSCALE; /* exp(-1/20) */ 152 SYSCTL_INT(_kern, OID_AUTO, ccpu, CTLFLAG_RD, &ccpu, 0, ""); 153 154 /* 155 * kernel uses `FSCALE', userland (SHOULD) use kern.fscale 156 */ 157 int fscale __unused = FSCALE; /* exported to systat */ 158 SYSCTL_INT(_kern, OID_AUTO, fscale, CTLFLAG_RD, 0, FSCALE, ""); 159 160 /* 161 * Recompute process priorities, once a second. 162 * 163 * Since the userland schedulers are typically event oriented, if the 164 * estcpu calculation at wakeup() time is not sufficient to make a 165 * process runnable relative to other processes in the system we have 166 * a 1-second recalc to help out. 167 * 168 * This code also allows us to store sysclock_t data in the process structure 169 * without fear of an overrun, since sysclock_t are guarenteed to hold 170 * several seconds worth of count. 171 * 172 * WARNING! callouts can preempt normal threads. However, they will not 173 * preempt a thread holding a spinlock so we *can* safely use spinlocks. 174 */ 175 static int schedcpu_stats(struct proc *p, void *data __unused); 176 static int schedcpu_resource(struct proc *p, void *data __unused); 177 178 static void 179 schedcpu(void *arg) 180 { 181 allproc_scan(schedcpu_stats, NULL); 182 allproc_scan(schedcpu_resource, NULL); 183 wakeup((caddr_t)&lbolt); 184 wakeup((caddr_t)&lbolt_syncer); 185 callout_reset(&schedcpu_callout, hz, schedcpu, NULL); 186 } 187 188 /* 189 * General process statistics once a second 190 */ 191 static int 192 schedcpu_stats(struct proc *p, void *data __unused) 193 { 194 struct lwp *lp; 195 196 crit_enter(); 197 p->p_swtime++; 198 FOREACH_LWP_IN_PROC(lp, p) { 199 if (lp->lwp_stat == LSSLEEP) 200 lp->lwp_slptime++; 201 202 /* 203 * Only recalculate processes that are active or have slept 204 * less then 2 seconds. The schedulers understand this. 205 */ 206 if (lp->lwp_slptime <= 1) { 207 p->p_usched->recalculate(lp); 208 } else { 209 lp->lwp_pctcpu = (lp->lwp_pctcpu * ccpu) >> FSHIFT; 210 } 211 } 212 crit_exit(); 213 return(0); 214 } 215 216 /* 217 * Resource checks. XXX break out since ksignal/killproc can block, 218 * limiting us to one process killed per second. There is probably 219 * a better way. 220 */ 221 static int 222 schedcpu_resource(struct proc *p, void *data __unused) 223 { 224 u_int64_t ttime; 225 struct lwp *lp; 226 227 crit_enter(); 228 if (p->p_stat == SIDL || 229 p->p_stat == SZOMB || 230 p->p_limit == NULL 231 ) { 232 crit_exit(); 233 return(0); 234 } 235 236 ttime = 0; 237 FOREACH_LWP_IN_PROC(lp, p) { 238 ttime += lp->lwp_thread->td_sticks; 239 ttime += lp->lwp_thread->td_uticks; 240 } 241 242 switch(plimit_testcpulimit(p->p_limit, ttime)) { 243 case PLIMIT_TESTCPU_KILL: 244 killproc(p, "exceeded maximum CPU limit"); 245 break; 246 case PLIMIT_TESTCPU_XCPU: 247 if ((p->p_flag & P_XCPU) == 0) { 248 p->p_flag |= P_XCPU; 249 ksignal(p, SIGXCPU); 250 } 251 break; 252 default: 253 break; 254 } 255 crit_exit(); 256 return(0); 257 } 258 259 /* 260 * This is only used by ps. Generate a cpu percentage use over 261 * a period of one second. 262 * 263 * MPSAFE 264 */ 265 void 266 updatepcpu(struct lwp *lp, int cpticks, int ttlticks) 267 { 268 fixpt_t acc; 269 int remticks; 270 271 acc = (cpticks << FSHIFT) / ttlticks; 272 if (ttlticks >= ESTCPUFREQ) { 273 lp->lwp_pctcpu = acc; 274 } else { 275 remticks = ESTCPUFREQ - ttlticks; 276 lp->lwp_pctcpu = (acc * ttlticks + lp->lwp_pctcpu * remticks) / 277 ESTCPUFREQ; 278 } 279 } 280 281 /* 282 * We're only looking at 7 bits of the address; everything is 283 * aligned to 4, lots of things are aligned to greater powers 284 * of 2. Shift right by 8, i.e. drop the bottom 256 worth. 285 */ 286 #define TABLESIZE 128 287 #define LOOKUP(x) (((intptr_t)(x) >> 8) & (TABLESIZE - 1)) 288 289 static cpumask_t slpque_cpumasks[TABLESIZE]; 290 291 /* 292 * General scheduler initialization. We force a reschedule 25 times 293 * a second by default. Note that cpu0 is initialized in early boot and 294 * cannot make any high level calls. 295 * 296 * Each cpu has its own sleep queue. 297 */ 298 void 299 sleep_gdinit(globaldata_t gd) 300 { 301 static struct tslpque slpque_cpu0[TABLESIZE]; 302 int i; 303 304 if (gd->gd_cpuid == 0) { 305 sched_quantum = (hz + 24) / 25; 306 hogticks = 2 * sched_quantum; 307 308 gd->gd_tsleep_hash = slpque_cpu0; 309 } else { 310 gd->gd_tsleep_hash = kmalloc(sizeof(slpque_cpu0), 311 M_TSLEEP, M_WAITOK | M_ZERO); 312 } 313 for (i = 0; i < TABLESIZE; ++i) 314 TAILQ_INIT(&gd->gd_tsleep_hash[i]); 315 } 316 317 /* 318 * General sleep call. Suspends the current process until a wakeup is 319 * performed on the specified identifier. The process will then be made 320 * runnable with the specified priority. Sleeps at most timo/hz seconds 321 * (0 means no timeout). If flags includes PCATCH flag, signals are checked 322 * before and after sleeping, else signals are not checked. Returns 0 if 323 * awakened, EWOULDBLOCK if the timeout expires. If PCATCH is set and a 324 * signal needs to be delivered, ERESTART is returned if the current system 325 * call should be restarted if possible, and EINTR is returned if the system 326 * call should be interrupted by the signal (return EINTR). 327 * 328 * Note that if we are a process, we release_curproc() before messing with 329 * the LWKT scheduler. 330 * 331 * During autoconfiguration or after a panic, a sleep will simply 332 * lower the priority briefly to allow interrupts, then return. 333 */ 334 int 335 tsleep(void *ident, int flags, const char *wmesg, int timo) 336 { 337 struct thread *td = curthread; 338 struct lwp *lp = td->td_lwp; 339 struct proc *p = td->td_proc; /* may be NULL */ 340 globaldata_t gd; 341 int sig; 342 int catch; 343 int id; 344 int error; 345 int oldpri; 346 struct callout thandle; 347 348 /* 349 * NOTE: removed KTRPOINT, it could cause races due to blocking 350 * even in stable. Just scrap it for now. 351 */ 352 if (cold || panicstr) { 353 /* 354 * After a panic, or during autoconfiguration, 355 * just give interrupts a chance, then just return; 356 * don't run any other procs or panic below, 357 * in case this is the idle process and already asleep. 358 */ 359 splz(); 360 oldpri = td->td_pri & TDPRI_MASK; 361 lwkt_setpri_self(safepri); 362 lwkt_switch(); 363 lwkt_setpri_self(oldpri); 364 return (0); 365 } 366 logtsleep(tsleep_beg); 367 gd = td->td_gd; 368 KKASSERT(td != &gd->gd_idlethread); /* you must be kidding! */ 369 370 /* 371 * NOTE: all of this occurs on the current cpu, including any 372 * callout-based wakeups, so a critical section is a sufficient 373 * interlock. 374 * 375 * The entire sequence through to where we actually sleep must 376 * run without breaking the critical section. 377 */ 378 id = LOOKUP(ident); 379 catch = flags & PCATCH; 380 error = 0; 381 sig = 0; 382 383 crit_enter_quick(td); 384 385 KASSERT(ident != NULL, ("tsleep: no ident")); 386 KASSERT(lp == NULL || 387 lp->lwp_stat == LSRUN || /* Obvious */ 388 lp->lwp_stat == LSSTOP, /* Set in tstop */ 389 ("tsleep %p %s %d", 390 ident, wmesg, lp->lwp_stat)); 391 392 /* 393 * Setup for the current process (if this is a process). 394 */ 395 if (lp) { 396 if (catch) { 397 /* 398 * Early termination if PCATCH was set and a 399 * signal is pending, interlocked with the 400 * critical section. 401 * 402 * Early termination only occurs when tsleep() is 403 * entered while in a normal LSRUN state. 404 */ 405 if ((sig = CURSIG(lp)) != 0) 406 goto resume; 407 408 /* 409 * Early termination if PCATCH was set and a 410 * mailbox signal was possibly delivered prior to 411 * the system call even being made, in order to 412 * allow the user to interlock without having to 413 * make additional system calls. 414 */ 415 if (p->p_flag & P_MAILBOX) 416 goto resume; 417 418 /* 419 * Causes ksignal to wake us up when. 420 */ 421 lp->lwp_flag |= LWP_SINTR; 422 } 423 424 /* 425 * Make sure the current process has been untangled from 426 * the userland scheduler and initialize slptime to start 427 * counting. 428 */ 429 if (flags & PNORESCHED) 430 td->td_flags |= TDF_NORESCHED; 431 p->p_usched->release_curproc(lp); 432 lp->lwp_slptime = 0; 433 } 434 435 /* 436 * Move our thread to the correct queue and setup our wchan, etc. 437 */ 438 lwkt_deschedule_self(td); 439 td->td_flags |= TDF_TSLEEPQ; 440 TAILQ_INSERT_TAIL(&gd->gd_tsleep_hash[id], td, td_threadq); 441 atomic_set_int(&slpque_cpumasks[id], gd->gd_cpumask); 442 443 td->td_wchan = ident; 444 td->td_wmesg = wmesg; 445 td->td_wdomain = flags & PDOMAIN_MASK; 446 447 /* 448 * Setup the timeout, if any 449 */ 450 if (timo) { 451 callout_init(&thandle); 452 callout_reset(&thandle, timo, endtsleep, td); 453 } 454 455 /* 456 * Beddy bye bye. 457 */ 458 if (lp) { 459 /* 460 * Ok, we are sleeping. Place us in the SSLEEP state. 461 */ 462 KKASSERT((lp->lwp_flag & LWP_ONRUNQ) == 0); 463 /* 464 * tstop() sets LSSTOP, so don't fiddle with that. 465 */ 466 if (lp->lwp_stat != LSSTOP) 467 lp->lwp_stat = LSSLEEP; 468 lp->lwp_ru.ru_nvcsw++; 469 lwkt_switch(); 470 471 /* 472 * And when we are woken up, put us back in LSRUN. If we 473 * slept for over a second, recalculate our estcpu. 474 */ 475 lp->lwp_stat = LSRUN; 476 if (lp->lwp_slptime) 477 p->p_usched->recalculate(lp); 478 lp->lwp_slptime = 0; 479 } else { 480 lwkt_switch(); 481 } 482 483 /* 484 * Make sure we haven't switched cpus while we were asleep. It's 485 * not supposed to happen. Cleanup our temporary flags. 486 */ 487 KKASSERT(gd == td->td_gd); 488 td->td_flags &= ~TDF_NORESCHED; 489 490 /* 491 * Cleanup the timeout. 492 */ 493 if (timo) { 494 if (td->td_flags & TDF_TIMEOUT) { 495 td->td_flags &= ~TDF_TIMEOUT; 496 error = EWOULDBLOCK; 497 } else { 498 callout_stop(&thandle); 499 } 500 } 501 502 /* 503 * Since td_threadq is used both for our run queue AND for the 504 * tsleep hash queue, we can't still be on it at this point because 505 * we've gotten cpu back. 506 */ 507 KASSERT((td->td_flags & TDF_TSLEEPQ) == 0, ("tsleep: impossible thread flags %08x", td->td_flags)); 508 td->td_wchan = NULL; 509 td->td_wmesg = NULL; 510 td->td_wdomain = 0; 511 512 /* 513 * Figure out the correct error return. If interrupted by a 514 * signal we want to return EINTR or ERESTART. 515 * 516 * If P_MAILBOX is set no automatic system call restart occurs 517 * and we return EINTR. P_MAILBOX is meant to be used as an 518 * interlock, the user must poll it prior to any system call 519 * that it wishes to interlock a mailbox signal against since 520 * the flag is cleared on *any* system call that sleeps. 521 */ 522 resume: 523 if (p) { 524 if (catch && error == 0) { 525 if ((p->p_flag & P_MAILBOX) && sig == 0) { 526 error = EINTR; 527 } else if (sig != 0 || (sig = CURSIG(lp))) { 528 if (SIGISMEMBER(p->p_sigacts->ps_sigintr, sig)) 529 error = EINTR; 530 else 531 error = ERESTART; 532 } 533 } 534 lp->lwp_flag &= ~(LWP_BREAKTSLEEP | LWP_SINTR); 535 p->p_flag &= ~P_MAILBOX; 536 } 537 logtsleep(tsleep_end); 538 crit_exit_quick(td); 539 return (error); 540 } 541 542 /* 543 * This is a dandy function that allows us to interlock tsleep/wakeup 544 * operations with unspecified upper level locks, such as lockmgr locks, 545 * simply by holding a critical section. The sequence is: 546 * 547 * (enter critical section) 548 * (acquire upper level lock) 549 * tsleep_interlock(blah) 550 * (release upper level lock) 551 * tsleep(blah, ...) 552 * (exit critical section) 553 * 554 * Basically this function sets our cpumask for the ident which informs 555 * other cpus that our cpu 'might' be waiting (or about to wait on) the 556 * hash index related to the ident. The critical section prevents another 557 * cpu's wakeup() from being processed on our cpu until we are actually 558 * able to enter the tsleep(). Thus, no race occurs between our attempt 559 * to release a resource and sleep, and another cpu's attempt to acquire 560 * a resource and call wakeup. 561 * 562 * There isn't much of a point to this function unless you call it while 563 * holding a critical section. 564 */ 565 static __inline void 566 _tsleep_interlock(globaldata_t gd, void *ident) 567 { 568 int id = LOOKUP(ident); 569 570 atomic_set_int(&slpque_cpumasks[id], gd->gd_cpumask); 571 } 572 573 void 574 tsleep_interlock(void *ident) 575 { 576 _tsleep_interlock(mycpu, ident); 577 } 578 579 /* 580 * Interlocked spinlock sleep. An exclusively held spinlock must 581 * be passed to msleep(). The function will atomically release the 582 * spinlock and tsleep on the ident, then reacquire the spinlock and 583 * return. 584 * 585 * This routine is fairly important along the critical path, so optimize it 586 * heavily. 587 */ 588 int 589 msleep(void *ident, struct spinlock *spin, int flags, 590 const char *wmesg, int timo) 591 { 592 globaldata_t gd = mycpu; 593 int error; 594 595 crit_enter_gd(gd); 596 _tsleep_interlock(gd, ident); 597 spin_unlock_wr_quick(gd, spin); 598 error = tsleep(ident, flags, wmesg, timo); 599 spin_lock_wr_quick(gd, spin); 600 crit_exit_gd(gd); 601 602 return (error); 603 } 604 605 /* 606 * Implement the timeout for tsleep. 607 * 608 * We set LWP_BREAKTSLEEP to indicate that an event has occured, but 609 * we only call setrunnable if the process is not stopped. 610 * 611 * This type of callout timeout is scheduled on the same cpu the process 612 * is sleeping on. Also, at the moment, the MP lock is held. 613 */ 614 static void 615 endtsleep(void *arg) 616 { 617 thread_t td = arg; 618 struct lwp *lp; 619 620 ASSERT_MP_LOCK_HELD(curthread); 621 crit_enter(); 622 623 /* 624 * cpu interlock. Thread flags are only manipulated on 625 * the cpu owning the thread. proc flags are only manipulated 626 * by the older of the MP lock. We have both. 627 */ 628 if (td->td_flags & TDF_TSLEEPQ) { 629 td->td_flags |= TDF_TIMEOUT; 630 631 if ((lp = td->td_lwp) != NULL) { 632 lp->lwp_flag |= LWP_BREAKTSLEEP; 633 if (lp->lwp_proc->p_stat != SSTOP) 634 setrunnable(lp); 635 } else { 636 unsleep_and_wakeup_thread(td); 637 } 638 } 639 crit_exit(); 640 } 641 642 /* 643 * Unsleep and wakeup a thread. This function runs without the MP lock 644 * which means that it can only manipulate thread state on the owning cpu, 645 * and cannot touch the process state at all. 646 */ 647 static 648 void 649 unsleep_and_wakeup_thread(struct thread *td) 650 { 651 globaldata_t gd = mycpu; 652 int id; 653 654 #ifdef SMP 655 if (td->td_gd != gd) { 656 lwkt_send_ipiq(td->td_gd, (ipifunc1_t)unsleep_and_wakeup_thread, td); 657 return; 658 } 659 #endif 660 crit_enter(); 661 if (td->td_flags & TDF_TSLEEPQ) { 662 td->td_flags &= ~TDF_TSLEEPQ; 663 id = LOOKUP(td->td_wchan); 664 TAILQ_REMOVE(&gd->gd_tsleep_hash[id], td, td_threadq); 665 if (TAILQ_FIRST(&gd->gd_tsleep_hash[id]) == NULL) 666 atomic_clear_int(&slpque_cpumasks[id], gd->gd_cpumask); 667 lwkt_schedule(td); 668 } 669 crit_exit(); 670 } 671 672 /* 673 * Make all processes sleeping on the specified identifier runnable. 674 * count may be zero or one only. 675 * 676 * The domain encodes the sleep/wakeup domain AND the first cpu to check 677 * (which is always the current cpu). As we iterate across cpus 678 * 679 * This call may run without the MP lock held. We can only manipulate thread 680 * state on the cpu owning the thread. We CANNOT manipulate process state 681 * at all. 682 */ 683 static void 684 _wakeup(void *ident, int domain) 685 { 686 struct tslpque *qp; 687 struct thread *td; 688 struct thread *ntd; 689 globaldata_t gd; 690 #ifdef SMP 691 cpumask_t mask; 692 cpumask_t tmask; 693 int startcpu; 694 int nextcpu; 695 #endif 696 int id; 697 698 crit_enter(); 699 logtsleep(wakeup_beg); 700 gd = mycpu; 701 id = LOOKUP(ident); 702 qp = &gd->gd_tsleep_hash[id]; 703 restart: 704 for (td = TAILQ_FIRST(qp); td != NULL; td = ntd) { 705 ntd = TAILQ_NEXT(td, td_threadq); 706 if (td->td_wchan == ident && 707 td->td_wdomain == (domain & PDOMAIN_MASK) 708 ) { 709 KKASSERT(td->td_flags & TDF_TSLEEPQ); 710 td->td_flags &= ~TDF_TSLEEPQ; 711 TAILQ_REMOVE(qp, td, td_threadq); 712 if (TAILQ_FIRST(qp) == NULL) { 713 atomic_clear_int(&slpque_cpumasks[id], 714 gd->gd_cpumask); 715 } 716 lwkt_schedule(td); 717 if (domain & PWAKEUP_ONE) 718 goto done; 719 goto restart; 720 } 721 } 722 723 #ifdef SMP 724 /* 725 * We finished checking the current cpu but there still may be 726 * more work to do. Either wakeup_one was requested and no matching 727 * thread was found, or a normal wakeup was requested and we have 728 * to continue checking cpus. 729 * 730 * The cpu that started the wakeup sequence is encoded in the domain. 731 * We use this information to determine which cpus still need to be 732 * checked, locate a candidate cpu, and chain the wakeup 733 * asynchronously with an IPI message. 734 * 735 * It should be noted that this scheme is actually less expensive then 736 * the old scheme when waking up multiple threads, since we send 737 * only one IPI message per target candidate which may then schedule 738 * multiple threads. Before we could have wound up sending an IPI 739 * message for each thread on the target cpu (!= current cpu) that 740 * needed to be woken up. 741 * 742 * NOTE: Wakeups occuring on remote cpus are asynchronous. This 743 * should be ok since we are passing idents in the IPI rather then 744 * thread pointers. 745 */ 746 if ((domain & PWAKEUP_MYCPU) == 0 && 747 (mask = slpque_cpumasks[id]) != 0 748 ) { 749 /* 750 * Look for a cpu that might have work to do. Mask out cpus 751 * which have already been processed. 752 * 753 * 31xxxxxxxxxxxxxxxxxxxxxxxxxxxxx0 754 * ^ ^ ^ 755 * start currentcpu start 756 * case2 case1 757 * * * * 758 * 11111111111111110000000000000111 case1 759 * 00000000111111110000000000000000 case2 760 * 761 * case1: We started at start_case1 and processed through 762 * to the current cpu. We have to check any bits 763 * after the current cpu, then check bits before 764 * the starting cpu. 765 * 766 * case2: We have already checked all the bits from 767 * start_case2 to the end, and from 0 to the current 768 * cpu. We just have the bits from the current cpu 769 * to start_case2 left to check. 770 */ 771 startcpu = PWAKEUP_DECODE(domain); 772 if (gd->gd_cpuid >= startcpu) { 773 /* 774 * CASE1 775 */ 776 tmask = mask & ~((gd->gd_cpumask << 1) - 1); 777 if (mask & tmask) { 778 nextcpu = bsfl(mask & tmask); 779 lwkt_send_ipiq2(globaldata_find(nextcpu), 780 _wakeup, ident, domain); 781 } else { 782 tmask = (1 << startcpu) - 1; 783 if (mask & tmask) { 784 nextcpu = bsfl(mask & tmask); 785 lwkt_send_ipiq2( 786 globaldata_find(nextcpu), 787 _wakeup, ident, domain); 788 } 789 } 790 } else { 791 /* 792 * CASE2 793 */ 794 tmask = ~((gd->gd_cpumask << 1) - 1) & 795 ((1 << startcpu) - 1); 796 if (mask & tmask) { 797 nextcpu = bsfl(mask & tmask); 798 lwkt_send_ipiq2(globaldata_find(nextcpu), 799 _wakeup, ident, domain); 800 } 801 } 802 } 803 #endif 804 done: 805 logtsleep(wakeup_end); 806 crit_exit(); 807 } 808 809 /* 810 * Wakeup all threads tsleep()ing on the specified ident, on all cpus 811 */ 812 void 813 wakeup(void *ident) 814 { 815 _wakeup(ident, PWAKEUP_ENCODE(0, mycpu->gd_cpuid)); 816 } 817 818 /* 819 * Wakeup one thread tsleep()ing on the specified ident, on any cpu. 820 */ 821 void 822 wakeup_one(void *ident) 823 { 824 /* XXX potentially round-robin the first responding cpu */ 825 _wakeup(ident, PWAKEUP_ENCODE(0, mycpu->gd_cpuid) | PWAKEUP_ONE); 826 } 827 828 /* 829 * Wakeup threads tsleep()ing on the specified ident on the current cpu 830 * only. 831 */ 832 void 833 wakeup_mycpu(void *ident) 834 { 835 _wakeup(ident, PWAKEUP_MYCPU); 836 } 837 838 /* 839 * Wakeup one thread tsleep()ing on the specified ident on the current cpu 840 * only. 841 */ 842 void 843 wakeup_mycpu_one(void *ident) 844 { 845 /* XXX potentially round-robin the first responding cpu */ 846 _wakeup(ident, PWAKEUP_MYCPU|PWAKEUP_ONE); 847 } 848 849 /* 850 * Wakeup all thread tsleep()ing on the specified ident on the specified cpu 851 * only. 852 */ 853 void 854 wakeup_oncpu(globaldata_t gd, void *ident) 855 { 856 #ifdef SMP 857 if (gd == mycpu) { 858 _wakeup(ident, PWAKEUP_MYCPU); 859 } else { 860 lwkt_send_ipiq2(gd, _wakeup, ident, PWAKEUP_MYCPU); 861 } 862 #else 863 _wakeup(ident, PWAKEUP_MYCPU); 864 #endif 865 } 866 867 /* 868 * Wakeup one thread tsleep()ing on the specified ident on the specified cpu 869 * only. 870 */ 871 void 872 wakeup_oncpu_one(globaldata_t gd, void *ident) 873 { 874 #ifdef SMP 875 if (gd == mycpu) { 876 _wakeup(ident, PWAKEUP_MYCPU | PWAKEUP_ONE); 877 } else { 878 lwkt_send_ipiq2(gd, _wakeup, ident, PWAKEUP_MYCPU | PWAKEUP_ONE); 879 } 880 #else 881 _wakeup(ident, PWAKEUP_MYCPU | PWAKEUP_ONE); 882 #endif 883 } 884 885 /* 886 * Wakeup all threads waiting on the specified ident that slept using 887 * the specified domain, on all cpus. 888 */ 889 void 890 wakeup_domain(void *ident, int domain) 891 { 892 _wakeup(ident, PWAKEUP_ENCODE(domain, mycpu->gd_cpuid)); 893 } 894 895 /* 896 * Wakeup one thread waiting on the specified ident that slept using 897 * the specified domain, on any cpu. 898 */ 899 void 900 wakeup_domain_one(void *ident, int domain) 901 { 902 /* XXX potentially round-robin the first responding cpu */ 903 _wakeup(ident, PWAKEUP_ENCODE(domain, mycpu->gd_cpuid) | PWAKEUP_ONE); 904 } 905 906 /* 907 * setrunnable() 908 * 909 * Make a process runnable. The MP lock must be held on call. This only 910 * has an effect if we are in SSLEEP. We only break out of the 911 * tsleep if LWP_BREAKTSLEEP is set, otherwise we just fix-up the state. 912 * 913 * NOTE: With the MP lock held we can only safely manipulate the process 914 * structure. We cannot safely manipulate the thread structure. 915 */ 916 void 917 setrunnable(struct lwp *lp) 918 { 919 crit_enter(); 920 ASSERT_MP_LOCK_HELD(curthread); 921 if (lp->lwp_stat == LSSTOP) 922 lp->lwp_stat = LSSLEEP; 923 if (lp->lwp_stat == LSSLEEP && (lp->lwp_flag & LWP_BREAKTSLEEP)) 924 unsleep_and_wakeup_thread(lp->lwp_thread); 925 crit_exit(); 926 } 927 928 /* 929 * The process is stopped due to some condition, usually because p_stat is 930 * set to SSTOP, but also possibly due to being traced. 931 * 932 * NOTE! If the caller sets SSTOP, the caller must also clear P_WAITED 933 * because the parent may check the child's status before the child actually 934 * gets to this routine. 935 * 936 * This routine is called with the current lwp only, typically just 937 * before returning to userland. 938 * 939 * Setting LWP_BREAKTSLEEP before entering the tsleep will cause a passive 940 * SIGCONT to break out of the tsleep. 941 */ 942 void 943 tstop(void) 944 { 945 struct lwp *lp = curthread->td_lwp; 946 struct proc *p = lp->lwp_proc; 947 948 lp->lwp_flag |= LWP_BREAKTSLEEP; 949 lp->lwp_stat = LSSTOP; 950 crit_enter(); 951 /* 952 * If LWP_WSTOP is set, we were sleeping 953 * while our process was stopped. At this point 954 * we were already counted as stopped. 955 */ 956 if ((lp->lwp_flag & LWP_WSTOP) == 0) { 957 /* 958 * If we're the last thread to stop, signal 959 * our parent. 960 */ 961 p->p_nstopped++; 962 lp->lwp_flag |= LWP_WSTOP; 963 if (p->p_nstopped == p->p_nthreads) { 964 p->p_flag &= ~P_WAITED; 965 wakeup(p->p_pptr); 966 if ((p->p_pptr->p_sigacts->ps_flag & PS_NOCLDSTOP) == 0) 967 ksignal(p->p_pptr, SIGCHLD); 968 } 969 } 970 tsleep(lp->lwp_proc, 0, "stop", 0); 971 p->p_nstopped--; 972 crit_exit(); 973 } 974 975 /* 976 * Yield / synchronous reschedule. This is a bit tricky because the trap 977 * code might have set a lazy release on the switch function. Setting 978 * P_PASSIVE_ACQ will ensure that the lazy release executes when we call 979 * switch, and that we are given a greater chance of affinity with our 980 * current cpu. 981 * 982 * We call lwkt_setpri_self() to rotate our thread to the end of the lwkt 983 * run queue. lwkt_switch() will also execute any assigned passive release 984 * (which usually calls release_curproc()), allowing a same/higher priority 985 * process to be designated as the current process. 986 * 987 * While it is possible for a lower priority process to be designated, 988 * it's call to lwkt_maybe_switch() in acquire_curproc() will likely 989 * round-robin back to us and we will be able to re-acquire the current 990 * process designation. 991 */ 992 void 993 uio_yield(void) 994 { 995 struct thread *td = curthread; 996 struct proc *p = td->td_proc; 997 998 lwkt_setpri_self(td->td_pri & TDPRI_MASK); 999 if (p) { 1000 p->p_flag |= P_PASSIVE_ACQ; 1001 lwkt_switch(); 1002 p->p_flag &= ~P_PASSIVE_ACQ; 1003 } else { 1004 lwkt_switch(); 1005 } 1006 } 1007 1008 /* 1009 * Compute a tenex style load average of a quantity on 1010 * 1, 5 and 15 minute intervals. 1011 */ 1012 static int loadav_count_runnable(struct lwp *p, void *data); 1013 1014 static void 1015 loadav(void *arg) 1016 { 1017 struct loadavg *avg; 1018 int i, nrun; 1019 1020 nrun = 0; 1021 alllwp_scan(loadav_count_runnable, &nrun); 1022 avg = &averunnable; 1023 for (i = 0; i < 3; i++) { 1024 avg->ldavg[i] = (cexp[i] * avg->ldavg[i] + 1025 nrun * FSCALE * (FSCALE - cexp[i])) >> FSHIFT; 1026 } 1027 1028 /* 1029 * Schedule the next update to occur after 5 seconds, but add a 1030 * random variation to avoid synchronisation with processes that 1031 * run at regular intervals. 1032 */ 1033 callout_reset(&loadav_callout, hz * 4 + (int)(krandom() % (hz * 2 + 1)), 1034 loadav, NULL); 1035 } 1036 1037 static int 1038 loadav_count_runnable(struct lwp *lp, void *data) 1039 { 1040 int *nrunp = data; 1041 thread_t td; 1042 1043 switch (lp->lwp_stat) { 1044 case LSRUN: 1045 if ((td = lp->lwp_thread) == NULL) 1046 break; 1047 if (td->td_flags & TDF_BLOCKED) 1048 break; 1049 ++*nrunp; 1050 break; 1051 default: 1052 break; 1053 } 1054 return(0); 1055 } 1056 1057 /* ARGSUSED */ 1058 static void 1059 sched_setup(void *dummy) 1060 { 1061 callout_init(&loadav_callout); 1062 callout_init(&schedcpu_callout); 1063 1064 /* Kick off timeout driven events by calling first time. */ 1065 schedcpu(NULL); 1066 loadav(NULL); 1067 } 1068 1069