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 1.71 2007/01/14 07:59:03 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 61 #include <sys/thread2.h> 62 #include <sys/spinlock2.h> 63 64 #include <machine/cpu.h> 65 #include <machine/smp.h> 66 67 TAILQ_HEAD(tslpque, thread); 68 69 static void sched_setup (void *dummy); 70 SYSINIT(sched_setup, SI_SUB_KICK_SCHEDULER, SI_ORDER_FIRST, sched_setup, NULL) 71 72 int hogticks; 73 int lbolt; 74 int lbolt_syncer; 75 int sched_quantum; /* Roundrobin scheduling quantum in ticks. */ 76 int ncpus; 77 int ncpus2, ncpus2_shift, ncpus2_mask; 78 int safepri; 79 80 static struct callout loadav_callout; 81 static struct callout schedcpu_callout; 82 MALLOC_DEFINE(M_TSLEEP, "tslpque", "tsleep queues"); 83 84 #if !defined(KTR_TSLEEP) 85 #define KTR_TSLEEP KTR_ALL 86 #endif 87 KTR_INFO_MASTER(tsleep); 88 KTR_INFO(KTR_TSLEEP, tsleep, tsleep_beg, 0, "tsleep enter", 0); 89 KTR_INFO(KTR_TSLEEP, tsleep, tsleep_end, 0, "tsleep exit", 0); 90 KTR_INFO(KTR_TSLEEP, tsleep, wakeup_beg, 0, "wakeup enter", 0); 91 KTR_INFO(KTR_TSLEEP, tsleep, wakeup_end, 0, "wakeup exit", 0); 92 #define logtsleep(name) KTR_LOG(tsleep_ ## name) 93 94 struct loadavg averunnable = 95 { {0, 0, 0}, FSCALE }; /* load average, of runnable procs */ 96 /* 97 * Constants for averages over 1, 5, and 15 minutes 98 * when sampling at 5 second intervals. 99 */ 100 static fixpt_t cexp[3] = { 101 0.9200444146293232 * FSCALE, /* exp(-1/12) */ 102 0.9834714538216174 * FSCALE, /* exp(-1/60) */ 103 0.9944598480048967 * FSCALE, /* exp(-1/180) */ 104 }; 105 106 static void endtsleep (void *); 107 static void unsleep_and_wakeup_thread(struct thread *td); 108 static void loadav (void *arg); 109 static void schedcpu (void *arg); 110 111 /* 112 * Adjust the scheduler quantum. The quantum is specified in microseconds. 113 * Note that 'tick' is in microseconds per tick. 114 */ 115 static int 116 sysctl_kern_quantum(SYSCTL_HANDLER_ARGS) 117 { 118 int error, new_val; 119 120 new_val = sched_quantum * tick; 121 error = sysctl_handle_int(oidp, &new_val, 0, req); 122 if (error != 0 || req->newptr == NULL) 123 return (error); 124 if (new_val < tick) 125 return (EINVAL); 126 sched_quantum = new_val / tick; 127 hogticks = 2 * sched_quantum; 128 return (0); 129 } 130 131 SYSCTL_PROC(_kern, OID_AUTO, quantum, CTLTYPE_INT|CTLFLAG_RW, 132 0, sizeof sched_quantum, sysctl_kern_quantum, "I", ""); 133 134 /* 135 * If `ccpu' is not equal to `exp(-1/20)' and you still want to use the 136 * faster/more-accurate formula, you'll have to estimate CCPU_SHIFT below 137 * and possibly adjust FSHIFT in "param.h" so that (FSHIFT >= CCPU_SHIFT). 138 * 139 * To estimate CCPU_SHIFT for exp(-1/20), the following formula was used: 140 * 1 - exp(-1/20) ~= 0.0487 ~= 0.0488 == 1 (fixed pt, *11* bits). 141 * 142 * If you don't want to bother with the faster/more-accurate formula, you 143 * can set CCPU_SHIFT to (FSHIFT + 1) which will use a slower/less-accurate 144 * (more general) method of calculating the %age of CPU used by a process. 145 * 146 * decay 95% of `p_pctcpu' in 60 seconds; see CCPU_SHIFT before changing 147 */ 148 #define CCPU_SHIFT 11 149 150 static fixpt_t ccpu = 0.95122942450071400909 * FSCALE; /* exp(-1/20) */ 151 SYSCTL_INT(_kern, OID_AUTO, ccpu, CTLFLAG_RD, &ccpu, 0, ""); 152 153 /* 154 * kernel uses `FSCALE', userland (SHOULD) use kern.fscale 155 */ 156 int fscale __unused = FSCALE; /* exported to systat */ 157 SYSCTL_INT(_kern, OID_AUTO, fscale, CTLFLAG_RD, 0, FSCALE, ""); 158 159 /* 160 * Recompute process priorities, once a second. 161 * 162 * Since the userland schedulers are typically event oriented, if the 163 * estcpu calculation at wakeup() time is not sufficient to make a 164 * process runnable relative to other processes in the system we have 165 * a 1-second recalc to help out. 166 * 167 * This code also allows us to store sysclock_t data in the process structure 168 * without fear of an overrun, since sysclock_t are guarenteed to hold 169 * several seconds worth of count. 170 * 171 * WARNING! callouts can preempt normal threads. However, they will not 172 * preempt a thread holding a spinlock so we *can* safely use spinlocks. 173 */ 174 static int schedcpu_stats(struct proc *p, void *data __unused); 175 static int schedcpu_resource(struct proc *p, void *data __unused); 176 177 static void 178 schedcpu(void *arg) 179 { 180 allproc_scan(schedcpu_stats, NULL); 181 allproc_scan(schedcpu_resource, NULL); 182 wakeup((caddr_t)&lbolt); 183 wakeup((caddr_t)&lbolt_syncer); 184 callout_reset(&schedcpu_callout, hz, schedcpu, NULL); 185 } 186 187 /* 188 * General process statistics once a second 189 */ 190 static int 191 schedcpu_stats(struct proc *p, void *data __unused) 192 { 193 crit_enter(); 194 p->p_swtime++; 195 if (p->p_stat == SSLEEP) 196 p->p_slptime++; 197 198 /* 199 * Only recalculate processes that are active or have slept 200 * less then 2 seconds. The schedulers understand this. 201 */ 202 if (p->p_slptime <= 1) { 203 p->p_usched->recalculate(&p->p_lwp); 204 } else { 205 p->p_pctcpu = (p->p_pctcpu * ccpu) >> FSHIFT; 206 } 207 crit_exit(); 208 return(0); 209 } 210 211 /* 212 * Resource checks. XXX break out since ksignal/killproc can block, 213 * limiting us to one process killed per second. There is probably 214 * a better way. 215 */ 216 static int 217 schedcpu_resource(struct proc *p, void *data __unused) 218 { 219 u_int64_t ttime; 220 221 crit_enter(); 222 if (p->p_stat == SIDL || 223 (p->p_flag & P_ZOMBIE) || 224 p->p_limit == NULL || 225 p->p_thread == NULL 226 ) { 227 crit_exit(); 228 return(0); 229 } 230 231 ttime = p->p_thread->td_sticks + p->p_thread->td_uticks; 232 233 switch(plimit_testcpulimit(p->p_limit, ttime)) { 234 case PLIMIT_TESTCPU_KILL: 235 killproc(p, "exceeded maximum CPU limit"); 236 break; 237 case PLIMIT_TESTCPU_XCPU: 238 if ((p->p_flag & P_XCPU) == 0) { 239 p->p_flag |= P_XCPU; 240 ksignal(p, SIGXCPU); 241 } 242 break; 243 default: 244 break; 245 } 246 crit_exit(); 247 return(0); 248 } 249 250 /* 251 * This is only used by ps. Generate a cpu percentage use over 252 * a period of one second. 253 * 254 * MPSAFE 255 */ 256 void 257 updatepcpu(struct lwp *lp, int cpticks, int ttlticks) 258 { 259 fixpt_t acc; 260 int remticks; 261 262 acc = (cpticks << FSHIFT) / ttlticks; 263 if (ttlticks >= ESTCPUFREQ) { 264 lp->lwp_pctcpu = acc; 265 } else { 266 remticks = ESTCPUFREQ - ttlticks; 267 lp->lwp_pctcpu = (acc * ttlticks + lp->lwp_pctcpu * remticks) / 268 ESTCPUFREQ; 269 } 270 } 271 272 /* 273 * We're only looking at 7 bits of the address; everything is 274 * aligned to 4, lots of things are aligned to greater powers 275 * of 2. Shift right by 8, i.e. drop the bottom 256 worth. 276 */ 277 #define TABLESIZE 128 278 #define LOOKUP(x) (((intptr_t)(x) >> 8) & (TABLESIZE - 1)) 279 280 static cpumask_t slpque_cpumasks[TABLESIZE]; 281 282 /* 283 * General scheduler initialization. We force a reschedule 25 times 284 * a second by default. Note that cpu0 is initialized in early boot and 285 * cannot make any high level calls. 286 * 287 * Each cpu has its own sleep queue. 288 */ 289 void 290 sleep_gdinit(globaldata_t gd) 291 { 292 static struct tslpque slpque_cpu0[TABLESIZE]; 293 int i; 294 295 if (gd->gd_cpuid == 0) { 296 sched_quantum = (hz + 24) / 25; 297 hogticks = 2 * sched_quantum; 298 299 gd->gd_tsleep_hash = slpque_cpu0; 300 } else { 301 gd->gd_tsleep_hash = kmalloc(sizeof(slpque_cpu0), 302 M_TSLEEP, M_WAITOK | M_ZERO); 303 } 304 for (i = 0; i < TABLESIZE; ++i) 305 TAILQ_INIT(&gd->gd_tsleep_hash[i]); 306 } 307 308 /* 309 * General sleep call. Suspends the current process until a wakeup is 310 * performed on the specified identifier. The process will then be made 311 * runnable with the specified priority. Sleeps at most timo/hz seconds 312 * (0 means no timeout). If flags includes PCATCH flag, signals are checked 313 * before and after sleeping, else signals are not checked. Returns 0 if 314 * awakened, EWOULDBLOCK if the timeout expires. If PCATCH is set and a 315 * signal needs to be delivered, ERESTART is returned if the current system 316 * call should be restarted if possible, and EINTR is returned if the system 317 * call should be interrupted by the signal (return EINTR). 318 * 319 * Note that if we are a process, we release_curproc() before messing with 320 * the LWKT scheduler. 321 * 322 * During autoconfiguration or after a panic, a sleep will simply 323 * lower the priority briefly to allow interrupts, then return. 324 */ 325 int 326 tsleep(void *ident, int flags, const char *wmesg, int timo) 327 { 328 struct thread *td = curthread; 329 struct proc *p = td->td_proc; /* may be NULL */ 330 globaldata_t gd; 331 int sig; 332 int catch; 333 int id; 334 int error; 335 int oldpri; 336 struct callout thandle; 337 338 /* 339 * NOTE: removed KTRPOINT, it could cause races due to blocking 340 * even in stable. Just scrap it for now. 341 */ 342 if (cold || panicstr) { 343 /* 344 * After a panic, or during autoconfiguration, 345 * just give interrupts a chance, then just return; 346 * don't run any other procs or panic below, 347 * in case this is the idle process and already asleep. 348 */ 349 splz(); 350 oldpri = td->td_pri & TDPRI_MASK; 351 lwkt_setpri_self(safepri); 352 lwkt_switch(); 353 lwkt_setpri_self(oldpri); 354 return (0); 355 } 356 logtsleep(tsleep_beg); 357 gd = td->td_gd; 358 KKASSERT(td != &gd->gd_idlethread); /* you must be kidding! */ 359 360 /* 361 * NOTE: all of this occurs on the current cpu, including any 362 * callout-based wakeups, so a critical section is a sufficient 363 * interlock. 364 * 365 * The entire sequence through to where we actually sleep must 366 * run without breaking the critical section. 367 */ 368 id = LOOKUP(ident); 369 catch = flags & PCATCH; 370 error = 0; 371 sig = 0; 372 373 crit_enter_quick(td); 374 375 KASSERT(ident != NULL, ("tsleep: no ident")); 376 KASSERT(p == NULL || p->p_stat == SRUN, ("tsleep %p %s %d", 377 ident, wmesg, p->p_stat)); 378 379 /* 380 * Setup for the current process (if this is a process). 381 */ 382 if (p) { 383 if (catch) { 384 /* 385 * Early termination if PCATCH was set and a 386 * signal is pending, interlocked with the 387 * critical section. 388 * 389 * Early termination only occurs when tsleep() is 390 * entered while in a normal SRUN state. 391 */ 392 if ((sig = CURSIG(p)) != 0) 393 goto resume; 394 395 /* 396 * Early termination if PCATCH was set and a 397 * mailbox signal was possibly delivered prior to 398 * the system call even being made, in order to 399 * allow the user to interlock without having to 400 * make additional system calls. 401 */ 402 if (p->p_flag & P_MAILBOX) 403 goto resume; 404 405 /* 406 * Causes ksignal to wake us up when. 407 */ 408 p->p_flag |= P_SINTR; 409 } 410 411 /* 412 * Make sure the current process has been untangled from 413 * the userland scheduler and initialize slptime to start 414 * counting. 415 */ 416 if (flags & PNORESCHED) 417 td->td_flags |= TDF_NORESCHED; 418 p->p_usched->release_curproc(&p->p_lwp); 419 p->p_slptime = 0; 420 } 421 422 /* 423 * Move our thread to the correct queue and setup our wchan, etc. 424 */ 425 lwkt_deschedule_self(td); 426 td->td_flags |= TDF_TSLEEPQ; 427 TAILQ_INSERT_TAIL(&gd->gd_tsleep_hash[id], td, td_threadq); 428 atomic_set_int(&slpque_cpumasks[id], gd->gd_cpumask); 429 430 td->td_wchan = ident; 431 td->td_wmesg = wmesg; 432 td->td_wdomain = flags & PDOMAIN_MASK; 433 434 /* 435 * Setup the timeout, if any 436 */ 437 if (timo) { 438 callout_init(&thandle); 439 callout_reset(&thandle, timo, endtsleep, td); 440 } 441 442 /* 443 * Beddy bye bye. 444 */ 445 if (p) { 446 /* 447 * Ok, we are sleeping. Place us in the SSLEEP state. 448 */ 449 KKASSERT((p->p_flag & P_ONRUNQ) == 0); 450 p->p_stat = SSLEEP; 451 p->p_lwp.lwp_ru.ru_nvcsw++; 452 lwkt_switch(); 453 454 /* 455 * And when we are woken up, put us back in SRUN. If we 456 * slept for over a second, recalculate our estcpu. 457 */ 458 p->p_stat = SRUN; 459 if (p->p_slptime) 460 p->p_usched->recalculate(&p->p_lwp); 461 p->p_slptime = 0; 462 } else { 463 lwkt_switch(); 464 } 465 466 /* 467 * Make sure we haven't switched cpus while we were asleep. It's 468 * not supposed to happen. Cleanup our temporary flags. 469 */ 470 KKASSERT(gd == td->td_gd); 471 td->td_flags &= ~TDF_NORESCHED; 472 473 /* 474 * Cleanup the timeout. 475 */ 476 if (timo) { 477 if (td->td_flags & TDF_TIMEOUT) { 478 td->td_flags &= ~TDF_TIMEOUT; 479 if (sig == 0) 480 error = EWOULDBLOCK; 481 } else { 482 callout_stop(&thandle); 483 } 484 } 485 486 /* 487 * Since td_threadq is used both for our run queue AND for the 488 * tsleep hash queue, we can't still be on it at this point because 489 * we've gotten cpu back. 490 */ 491 KASSERT((td->td_flags & TDF_TSLEEPQ) == 0, ("tsleep: impossible thread flags %08x", td->td_flags)); 492 td->td_wchan = NULL; 493 td->td_wmesg = NULL; 494 td->td_wdomain = 0; 495 496 /* 497 * Figure out the correct error return. If interrupted by a 498 * signal we want to return EINTR or ERESTART. 499 * 500 * If P_MAILBOX is set no automatic system call restart occurs 501 * and we return EINTR. P_MAILBOX is meant to be used as an 502 * interlock, the user must poll it prior to any system call 503 * that it wishes to interlock a mailbox signal against since 504 * the flag is cleared on *any* system call that sleeps. 505 */ 506 resume: 507 if (p) { 508 if (catch && error == 0) { 509 if ((p->p_flag & P_MAILBOX) && sig == 0) { 510 error = EINTR; 511 } else if ((sig != 0 || (sig = CURSIG(p)))) { 512 if (SIGISMEMBER(p->p_sigacts->ps_sigintr, sig)) 513 error = EINTR; 514 else 515 error = ERESTART; 516 } 517 } 518 p->p_flag &= ~(P_BREAKTSLEEP | P_SINTR | P_MAILBOX); 519 } 520 logtsleep(tsleep_end); 521 crit_exit_quick(td); 522 return (error); 523 } 524 525 /* 526 * This is a dandy function that allows us to interlock tsleep/wakeup 527 * operations with unspecified upper level locks, such as lockmgr locks, 528 * simply by holding a critical section. The sequence is: 529 * 530 * (enter critical section) 531 * (acquire upper level lock) 532 * tsleep_interlock(blah) 533 * (release upper level lock) 534 * tsleep(blah, ...) 535 * (exit critical section) 536 * 537 * Basically this function sets our cpumask for the ident which informs 538 * other cpus that our cpu 'might' be waiting (or about to wait on) the 539 * hash index related to the ident. The critical section prevents another 540 * cpu's wakeup() from being processed on our cpu until we are actually 541 * able to enter the tsleep(). Thus, no race occurs between our attempt 542 * to release a resource and sleep, and another cpu's attempt to acquire 543 * a resource and call wakeup. 544 * 545 * There isn't much of a point to this function unless you call it while 546 * holding a critical section. 547 */ 548 static __inline void 549 _tsleep_interlock(globaldata_t gd, void *ident) 550 { 551 int id = LOOKUP(ident); 552 553 atomic_set_int(&slpque_cpumasks[id], gd->gd_cpumask); 554 } 555 556 void 557 tsleep_interlock(void *ident) 558 { 559 _tsleep_interlock(mycpu, ident); 560 } 561 562 /* 563 * Interlocked spinlock sleep. An exclusively held spinlock must 564 * be passed to msleep(). The function will atomically release the 565 * spinlock and tsleep on the ident, then reacquire the spinlock and 566 * return. 567 * 568 * This routine is fairly important along the critical path, so optimize it 569 * heavily. 570 */ 571 int 572 msleep(void *ident, struct spinlock *spin, int flags, 573 const char *wmesg, int timo) 574 { 575 globaldata_t gd = mycpu; 576 int error; 577 578 crit_enter_gd(gd); 579 _tsleep_interlock(gd, ident); 580 spin_unlock_wr_quick(gd, spin); 581 error = tsleep(ident, flags, wmesg, timo); 582 spin_lock_wr_quick(gd, spin); 583 crit_exit_gd(gd); 584 585 return (error); 586 } 587 588 /* 589 * Implement the timeout for tsleep. 590 * 591 * We set P_BREAKTSLEEP to indicate that an event has occured, but 592 * we only call setrunnable if the process is not stopped. 593 * 594 * This type of callout timeout is scheduled on the same cpu the process 595 * is sleeping on. Also, at the moment, the MP lock is held. 596 */ 597 static void 598 endtsleep(void *arg) 599 { 600 thread_t td = arg; 601 struct proc *p; 602 603 ASSERT_MP_LOCK_HELD(curthread); 604 crit_enter(); 605 606 /* 607 * cpu interlock. Thread flags are only manipulated on 608 * the cpu owning the thread. proc flags are only manipulated 609 * by the older of the MP lock. We have both. 610 */ 611 if (td->td_flags & TDF_TSLEEPQ) { 612 td->td_flags |= TDF_TIMEOUT; 613 614 if ((p = td->td_proc) != NULL) { 615 p->p_flag |= P_BREAKTSLEEP; 616 if ((p->p_flag & P_STOPPED) == 0) 617 setrunnable(p); 618 } else { 619 unsleep_and_wakeup_thread(td); 620 } 621 } 622 crit_exit(); 623 } 624 625 /* 626 * Unsleep and wakeup a thread. This function runs without the MP lock 627 * which means that it can only manipulate thread state on the owning cpu, 628 * and cannot touch the process state at all. 629 */ 630 static 631 void 632 unsleep_and_wakeup_thread(struct thread *td) 633 { 634 globaldata_t gd = mycpu; 635 int id; 636 637 #ifdef SMP 638 if (td->td_gd != gd) { 639 lwkt_send_ipiq(td->td_gd, (ipifunc1_t)unsleep_and_wakeup_thread, td); 640 return; 641 } 642 #endif 643 crit_enter(); 644 if (td->td_flags & TDF_TSLEEPQ) { 645 td->td_flags &= ~TDF_TSLEEPQ; 646 id = LOOKUP(td->td_wchan); 647 TAILQ_REMOVE(&gd->gd_tsleep_hash[id], td, td_threadq); 648 if (TAILQ_FIRST(&gd->gd_tsleep_hash[id]) == NULL) 649 atomic_clear_int(&slpque_cpumasks[id], gd->gd_cpumask); 650 lwkt_schedule(td); 651 } 652 crit_exit(); 653 } 654 655 /* 656 * Make all processes sleeping on the specified identifier runnable. 657 * count may be zero or one only. 658 * 659 * The domain encodes the sleep/wakeup domain AND the first cpu to check 660 * (which is always the current cpu). As we iterate across cpus 661 * 662 * This call may run without the MP lock held. We can only manipulate thread 663 * state on the cpu owning the thread. We CANNOT manipulate process state 664 * at all. 665 */ 666 static void 667 _wakeup(void *ident, int domain) 668 { 669 struct tslpque *qp; 670 struct thread *td; 671 struct thread *ntd; 672 globaldata_t gd; 673 #ifdef SMP 674 cpumask_t mask; 675 cpumask_t tmask; 676 int startcpu; 677 int nextcpu; 678 #endif 679 int id; 680 681 crit_enter(); 682 logtsleep(wakeup_beg); 683 gd = mycpu; 684 id = LOOKUP(ident); 685 qp = &gd->gd_tsleep_hash[id]; 686 restart: 687 for (td = TAILQ_FIRST(qp); td != NULL; td = ntd) { 688 ntd = TAILQ_NEXT(td, td_threadq); 689 if (td->td_wchan == ident && 690 td->td_wdomain == (domain & PDOMAIN_MASK) 691 ) { 692 KKASSERT(td->td_flags & TDF_TSLEEPQ); 693 td->td_flags &= ~TDF_TSLEEPQ; 694 TAILQ_REMOVE(qp, td, td_threadq); 695 if (TAILQ_FIRST(qp) == NULL) { 696 atomic_clear_int(&slpque_cpumasks[id], 697 gd->gd_cpumask); 698 } 699 lwkt_schedule(td); 700 if (domain & PWAKEUP_ONE) 701 goto done; 702 goto restart; 703 } 704 } 705 706 #ifdef SMP 707 /* 708 * We finished checking the current cpu but there still may be 709 * more work to do. Either wakeup_one was requested and no matching 710 * thread was found, or a normal wakeup was requested and we have 711 * to continue checking cpus. 712 * 713 * The cpu that started the wakeup sequence is encoded in the domain. 714 * We use this information to determine which cpus still need to be 715 * checked, locate a candidate cpu, and chain the wakeup 716 * asynchronously with an IPI message. 717 * 718 * It should be noted that this scheme is actually less expensive then 719 * the old scheme when waking up multiple threads, since we send 720 * only one IPI message per target candidate which may then schedule 721 * multiple threads. Before we could have wound up sending an IPI 722 * message for each thread on the target cpu (!= current cpu) that 723 * needed to be woken up. 724 * 725 * NOTE: Wakeups occuring on remote cpus are asynchronous. This 726 * should be ok since we are passing idents in the IPI rather then 727 * thread pointers. 728 */ 729 if ((domain & PWAKEUP_MYCPU) == 0 && 730 (mask = slpque_cpumasks[id]) != 0 731 ) { 732 /* 733 * Look for a cpu that might have work to do. Mask out cpus 734 * which have already been processed. 735 * 736 * 31xxxxxxxxxxxxxxxxxxxxxxxxxxxxx0 737 * ^ ^ ^ 738 * start currentcpu start 739 * case2 case1 740 * * * * 741 * 11111111111111110000000000000111 case1 742 * 00000000111111110000000000000000 case2 743 * 744 * case1: We started at start_case1 and processed through 745 * to the current cpu. We have to check any bits 746 * after the current cpu, then check bits before 747 * the starting cpu. 748 * 749 * case2: We have already checked all the bits from 750 * start_case2 to the end, and from 0 to the current 751 * cpu. We just have the bits from the current cpu 752 * to start_case2 left to check. 753 */ 754 startcpu = PWAKEUP_DECODE(domain); 755 if (gd->gd_cpuid >= startcpu) { 756 /* 757 * CASE1 758 */ 759 tmask = mask & ~((gd->gd_cpumask << 1) - 1); 760 if (mask & tmask) { 761 nextcpu = bsfl(mask & tmask); 762 lwkt_send_ipiq2(globaldata_find(nextcpu), 763 _wakeup, ident, domain); 764 } else { 765 tmask = (1 << startcpu) - 1; 766 if (mask & tmask) { 767 nextcpu = bsfl(mask & tmask); 768 lwkt_send_ipiq2( 769 globaldata_find(nextcpu), 770 _wakeup, ident, domain); 771 } 772 } 773 } else { 774 /* 775 * CASE2 776 */ 777 tmask = ~((gd->gd_cpumask << 1) - 1) & 778 ((1 << startcpu) - 1); 779 if (mask & tmask) { 780 nextcpu = bsfl(mask & tmask); 781 lwkt_send_ipiq2(globaldata_find(nextcpu), 782 _wakeup, ident, domain); 783 } 784 } 785 } 786 #endif 787 done: 788 logtsleep(wakeup_end); 789 crit_exit(); 790 } 791 792 /* 793 * Wakeup all threads tsleep()ing on the specified ident, on all cpus 794 */ 795 void 796 wakeup(void *ident) 797 { 798 _wakeup(ident, PWAKEUP_ENCODE(0, mycpu->gd_cpuid)); 799 } 800 801 /* 802 * Wakeup one thread tsleep()ing on the specified ident, on any cpu. 803 */ 804 void 805 wakeup_one(void *ident) 806 { 807 /* XXX potentially round-robin the first responding cpu */ 808 _wakeup(ident, PWAKEUP_ENCODE(0, mycpu->gd_cpuid) | PWAKEUP_ONE); 809 } 810 811 /* 812 * Wakeup threads tsleep()ing on the specified ident on the current cpu 813 * only. 814 */ 815 void 816 wakeup_mycpu(void *ident) 817 { 818 _wakeup(ident, PWAKEUP_MYCPU); 819 } 820 821 /* 822 * Wakeup one thread tsleep()ing on the specified ident on the current cpu 823 * only. 824 */ 825 void 826 wakeup_mycpu_one(void *ident) 827 { 828 /* XXX potentially round-robin the first responding cpu */ 829 _wakeup(ident, PWAKEUP_MYCPU|PWAKEUP_ONE); 830 } 831 832 /* 833 * Wakeup all thread tsleep()ing on the specified ident on the specified cpu 834 * only. 835 */ 836 void 837 wakeup_oncpu(globaldata_t gd, void *ident) 838 { 839 #ifdef SMP 840 if (gd == mycpu) { 841 _wakeup(ident, PWAKEUP_MYCPU); 842 } else { 843 lwkt_send_ipiq2(gd, _wakeup, ident, PWAKEUP_MYCPU); 844 } 845 #else 846 _wakeup(ident, PWAKEUP_MYCPU); 847 #endif 848 } 849 850 /* 851 * Wakeup one thread tsleep()ing on the specified ident on the specified cpu 852 * only. 853 */ 854 void 855 wakeup_oncpu_one(globaldata_t gd, void *ident) 856 { 857 #ifdef SMP 858 if (gd == mycpu) { 859 _wakeup(ident, PWAKEUP_MYCPU | PWAKEUP_ONE); 860 } else { 861 lwkt_send_ipiq2(gd, _wakeup, ident, PWAKEUP_MYCPU | PWAKEUP_ONE); 862 } 863 #else 864 _wakeup(ident, PWAKEUP_MYCPU | PWAKEUP_ONE); 865 #endif 866 } 867 868 /* 869 * Wakeup all threads waiting on the specified ident that slept using 870 * the specified domain, on all cpus. 871 */ 872 void 873 wakeup_domain(void *ident, int domain) 874 { 875 _wakeup(ident, PWAKEUP_ENCODE(domain, mycpu->gd_cpuid)); 876 } 877 878 /* 879 * Wakeup one thread waiting on the specified ident that slept using 880 * the specified domain, on any cpu. 881 */ 882 void 883 wakeup_domain_one(void *ident, int domain) 884 { 885 /* XXX potentially round-robin the first responding cpu */ 886 _wakeup(ident, PWAKEUP_ENCODE(domain, mycpu->gd_cpuid) | PWAKEUP_ONE); 887 } 888 889 /* 890 * setrunnable() 891 * 892 * Make a process runnable. The MP lock must be held on call. This only 893 * has an effect if we are in SSLEEP. We only break out of the 894 * tsleep if P_BREAKTSLEEP is set, otherwise we just fix-up the state. 895 * 896 * NOTE: With the MP lock held we can only safely manipulate the process 897 * structure. We cannot safely manipulate the thread structure. 898 */ 899 void 900 setrunnable(struct proc *p) 901 { 902 crit_enter(); 903 ASSERT_MP_LOCK_HELD(curthread); 904 p->p_flag &= ~P_STOPPED; 905 if (p->p_stat == SSLEEP && (p->p_flag & P_BREAKTSLEEP)) { 906 unsleep_and_wakeup_thread(p->p_thread); 907 } 908 crit_exit(); 909 } 910 911 /* 912 * The process is stopped due to some condition, usually because P_STOPPED 913 * is set but also possibly due to being traced. 914 * 915 * NOTE! If the caller sets P_STOPPED, the caller must also clear P_WAITED 916 * because the parent may check the child's status before the child actually 917 * gets to this routine. 918 * 919 * This routine is called with the current process only, typically just 920 * before returning to userland. 921 * 922 * Setting P_BREAKTSLEEP before entering the tsleep will cause a passive 923 * SIGCONT to break out of the tsleep. 924 */ 925 void 926 tstop(struct proc *p) 927 { 928 wakeup((caddr_t)p->p_pptr); 929 p->p_flag |= P_BREAKTSLEEP; 930 tsleep(p, 0, "stop", 0); 931 } 932 933 /* 934 * Yield / synchronous reschedule. This is a bit tricky because the trap 935 * code might have set a lazy release on the switch function. Setting 936 * P_PASSIVE_ACQ will ensure that the lazy release executes when we call 937 * switch, and that we are given a greater chance of affinity with our 938 * current cpu. 939 * 940 * We call lwkt_setpri_self() to rotate our thread to the end of the lwkt 941 * run queue. lwkt_switch() will also execute any assigned passive release 942 * (which usually calls release_curproc()), allowing a same/higher priority 943 * process to be designated as the current process. 944 * 945 * While it is possible for a lower priority process to be designated, 946 * it's call to lwkt_maybe_switch() in acquire_curproc() will likely 947 * round-robin back to us and we will be able to re-acquire the current 948 * process designation. 949 */ 950 void 951 uio_yield(void) 952 { 953 struct thread *td = curthread; 954 struct proc *p = td->td_proc; 955 956 lwkt_setpri_self(td->td_pri & TDPRI_MASK); 957 if (p) { 958 p->p_flag |= P_PASSIVE_ACQ; 959 lwkt_switch(); 960 p->p_flag &= ~P_PASSIVE_ACQ; 961 } else { 962 lwkt_switch(); 963 } 964 } 965 966 /* 967 * Compute a tenex style load average of a quantity on 968 * 1, 5 and 15 minute intervals. 969 */ 970 static int loadav_count_runnable(struct proc *p, void *data); 971 972 static void 973 loadav(void *arg) 974 { 975 struct loadavg *avg; 976 int i, nrun; 977 978 nrun = 0; 979 allproc_scan(loadav_count_runnable, &nrun); 980 avg = &averunnable; 981 for (i = 0; i < 3; i++) { 982 avg->ldavg[i] = (cexp[i] * avg->ldavg[i] + 983 nrun * FSCALE * (FSCALE - cexp[i])) >> FSHIFT; 984 } 985 986 /* 987 * Schedule the next update to occur after 5 seconds, but add a 988 * random variation to avoid synchronisation with processes that 989 * run at regular intervals. 990 */ 991 callout_reset(&loadav_callout, hz * 4 + (int)(krandom() % (hz * 2 + 1)), 992 loadav, NULL); 993 } 994 995 static int 996 loadav_count_runnable(struct proc *p, void *data) 997 { 998 int *nrunp = data; 999 thread_t td; 1000 1001 switch (p->p_stat) { 1002 case SRUN: 1003 if ((td = p->p_thread) == NULL) 1004 break; 1005 if (td->td_flags & TDF_BLOCKED) 1006 break; 1007 /* fall through */ 1008 case SIDL: 1009 ++*nrunp; 1010 break; 1011 default: 1012 break; 1013 } 1014 return(0); 1015 } 1016 1017 /* ARGSUSED */ 1018 static void 1019 sched_setup(void *dummy) 1020 { 1021 callout_init(&loadav_callout); 1022 callout_init(&schedcpu_callout); 1023 1024 /* Kick off timeout driven events by calling first time. */ 1025 schedcpu(NULL); 1026 loadav(NULL); 1027 } 1028 1029