Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)
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sys/kern/sched_4bsd.c
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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 * 4. Neither the name of the University nor the names of its contributors 19 * may be used to endorse or promote products derived from this software 20 * without specific prior written permission. 21 * 22 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 25 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 32 * SUCH DAMAGE. 33 */ 34 35 #include <sys/cdefs.h> 36 __FBSDID("$FreeBSD: releng/8.3/sys/kern/sched_4bsd.c 230080 2012-01-13 20:15:49Z jhb $"); 37 38 #include "opt_hwpmc_hooks.h" 39 #include "opt_sched.h" 40 #include "opt_kdtrace.h" 41 42 #include <sys/param.h> 43 #include <sys/systm.h> 44 #include <sys/cpuset.h> 45 #include <sys/kernel.h> 46 #include <sys/ktr.h> 47 #include <sys/lock.h> 48 #include <sys/kthread.h> 49 #include <sys/mutex.h> 50 #include <sys/proc.h> 51 #include <sys/resourcevar.h> 52 #include <sys/sched.h> 53 #include <sys/smp.h> 54 #include <sys/sysctl.h> 55 #include <sys/sx.h> 56 #include <sys/turnstile.h> 57 #include <sys/umtx.h> 58 #include <machine/pcb.h> 59 #include <machine/smp.h> 60 61 #ifdef HWPMC_HOOKS 62 #include <sys/pmckern.h> 63 #endif 64 65 #ifdef KDTRACE_HOOKS 66 #include <sys/dtrace_bsd.h> 67 int dtrace_vtime_active; 68 dtrace_vtime_switch_func_t dtrace_vtime_switch_func; 69 #endif 70 71 /* 72 * INVERSE_ESTCPU_WEIGHT is only suitable for statclock() frequencies in 73 * the range 100-256 Hz (approximately). 74 */ 75 #define ESTCPULIM(e) \ 76 min((e), INVERSE_ESTCPU_WEIGHT * (NICE_WEIGHT * (PRIO_MAX - PRIO_MIN) - \ 77 RQ_PPQ) + INVERSE_ESTCPU_WEIGHT - 1) 78 #ifdef SMP 79 #define INVERSE_ESTCPU_WEIGHT (8 * smp_cpus) 80 #else 81 #define INVERSE_ESTCPU_WEIGHT 8 /* 1 / (priorities per estcpu level). */ 82 #endif 83 #define NICE_WEIGHT 1 /* Priorities per nice level. */ 84 85 #define TS_NAME_LEN (MAXCOMLEN + sizeof(" td ") + sizeof(__XSTRING(UINT_MAX))) 86 87 /* 88 * The schedulable entity that runs a context. 89 * This is an extension to the thread structure and is tailored to 90 * the requirements of this scheduler 91 */ 92 struct td_sched { 93 fixpt_t ts_pctcpu; /* (j) %cpu during p_swtime. */ 94 int ts_cpticks; /* (j) Ticks of cpu time. */ 95 int ts_slptime; /* (j) Seconds !RUNNING. */ 96 int ts_flags; 97 struct runq *ts_runq; /* runq the thread is currently on */ 98 #ifdef KTR 99 char ts_name[TS_NAME_LEN]; 100 #endif 101 }; 102 103 /* flags kept in td_flags */ 104 #define TDF_DIDRUN TDF_SCHED0 /* thread actually ran. */ 105 #define TDF_BOUND TDF_SCHED1 /* Bound to one CPU. */ 106 107 /* flags kept in ts_flags */ 108 #define TSF_AFFINITY 0x0001 /* Has a non-"full" CPU set. */ 109 110 #define SKE_RUNQ_PCPU(ts) \ 111 ((ts)->ts_runq != 0 && (ts)->ts_runq != &runq) 112 113 #define THREAD_CAN_SCHED(td, cpu) \ 114 CPU_ISSET((cpu), &(td)->td_cpuset->cs_mask) 115 116 static struct td_sched td_sched0; 117 struct mtx sched_lock; 118 119 static int sched_tdcnt; /* Total runnable threads in the system. */ 120 static int sched_quantum; /* Roundrobin scheduling quantum in ticks. */ 121 #define SCHED_QUANTUM (hz / 10) /* Default sched quantum */ 122 123 static void setup_runqs(void); 124 static void schedcpu(void); 125 static void schedcpu_thread(void); 126 static void sched_priority(struct thread *td, u_char prio); 127 static void sched_setup(void *dummy); 128 static void maybe_resched(struct thread *td); 129 static void updatepri(struct thread *td); 130 static void resetpriority(struct thread *td); 131 static void resetpriority_thread(struct thread *td); 132 #ifdef SMP 133 static int sched_pickcpu(struct thread *td); 134 static int forward_wakeup(int cpunum); 135 static void kick_other_cpu(int pri, int cpuid); 136 #endif 137 138 static struct kproc_desc sched_kp = { 139 "schedcpu", 140 schedcpu_thread, 141 NULL 142 }; 143 SYSINIT(schedcpu, SI_SUB_RUN_SCHEDULER, SI_ORDER_FIRST, kproc_start, 144 &sched_kp); 145 SYSINIT(sched_setup, SI_SUB_RUN_QUEUE, SI_ORDER_FIRST, sched_setup, NULL); 146 147 /* 148 * Global run queue. 149 */ 150 static struct runq runq; 151 152 #ifdef SMP 153 /* 154 * Per-CPU run queues 155 */ 156 static struct runq runq_pcpu[MAXCPU]; 157 long runq_length[MAXCPU]; 158 #endif 159 160 static void 161 setup_runqs(void) 162 { 163 #ifdef SMP 164 int i; 165 166 for (i = 0; i < MAXCPU; ++i) 167 runq_init(&runq_pcpu[i]); 168 #endif 169 170 runq_init(&runq); 171 } 172 173 static int 174 sysctl_kern_quantum(SYSCTL_HANDLER_ARGS) 175 { 176 int error, new_val; 177 178 new_val = sched_quantum * tick; 179 error = sysctl_handle_int(oidp, &new_val, 0, req); 180 if (error != 0 || req->newptr == NULL) 181 return (error); 182 if (new_val < tick) 183 return (EINVAL); 184 sched_quantum = new_val / tick; 185 hogticks = 2 * sched_quantum; 186 return (0); 187 } 188 189 SYSCTL_NODE(_kern, OID_AUTO, sched, CTLFLAG_RD, 0, "Scheduler"); 190 191 SYSCTL_STRING(_kern_sched, OID_AUTO, name, CTLFLAG_RD, "4BSD", 0, 192 "Scheduler name"); 193 194 SYSCTL_PROC(_kern_sched, OID_AUTO, quantum, CTLTYPE_INT | CTLFLAG_RW, 195 0, sizeof sched_quantum, sysctl_kern_quantum, "I", 196 "Roundrobin scheduling quantum in microseconds"); 197 198 #ifdef SMP 199 /* Enable forwarding of wakeups to all other cpus */ 200 SYSCTL_NODE(_kern_sched, OID_AUTO, ipiwakeup, CTLFLAG_RD, NULL, "Kernel SMP"); 201 202 static int runq_fuzz = 1; 203 SYSCTL_INT(_kern_sched, OID_AUTO, runq_fuzz, CTLFLAG_RW, &runq_fuzz, 0, ""); 204 205 static int forward_wakeup_enabled = 1; 206 SYSCTL_INT(_kern_sched_ipiwakeup, OID_AUTO, enabled, CTLFLAG_RW, 207 &forward_wakeup_enabled, 0, 208 "Forwarding of wakeup to idle CPUs"); 209 210 static int forward_wakeups_requested = 0; 211 SYSCTL_INT(_kern_sched_ipiwakeup, OID_AUTO, requested, CTLFLAG_RD, 212 &forward_wakeups_requested, 0, 213 "Requests for Forwarding of wakeup to idle CPUs"); 214 215 static int forward_wakeups_delivered = 0; 216 SYSCTL_INT(_kern_sched_ipiwakeup, OID_AUTO, delivered, CTLFLAG_RD, 217 &forward_wakeups_delivered, 0, 218 "Completed Forwarding of wakeup to idle CPUs"); 219 220 static int forward_wakeup_use_mask = 1; 221 SYSCTL_INT(_kern_sched_ipiwakeup, OID_AUTO, usemask, CTLFLAG_RW, 222 &forward_wakeup_use_mask, 0, 223 "Use the mask of idle cpus"); 224 225 static int forward_wakeup_use_loop = 0; 226 SYSCTL_INT(_kern_sched_ipiwakeup, OID_AUTO, useloop, CTLFLAG_RW, 227 &forward_wakeup_use_loop, 0, 228 "Use a loop to find idle cpus"); 229 230 static int forward_wakeup_use_single = 0; 231 SYSCTL_INT(_kern_sched_ipiwakeup, OID_AUTO, onecpu, CTLFLAG_RW, 232 &forward_wakeup_use_single, 0, 233 "Only signal one idle cpu"); 234 235 static int forward_wakeup_use_htt = 0; 236 SYSCTL_INT(_kern_sched_ipiwakeup, OID_AUTO, htt2, CTLFLAG_RW, 237 &forward_wakeup_use_htt, 0, 238 "account for htt"); 239 240 #endif 241 #if 0 242 static int sched_followon = 0; 243 SYSCTL_INT(_kern_sched, OID_AUTO, followon, CTLFLAG_RW, 244 &sched_followon, 0, 245 "allow threads to share a quantum"); 246 #endif 247 248 static __inline void 249 sched_load_add(void) 250 { 251 252 sched_tdcnt++; 253 KTR_COUNTER0(KTR_SCHED, "load", "global load", sched_tdcnt); 254 } 255 256 static __inline void 257 sched_load_rem(void) 258 { 259 260 sched_tdcnt--; 261 KTR_COUNTER0(KTR_SCHED, "load", "global load", sched_tdcnt); 262 } 263 /* 264 * Arrange to reschedule if necessary, taking the priorities and 265 * schedulers into account. 266 */ 267 static void 268 maybe_resched(struct thread *td) 269 { 270 271 THREAD_LOCK_ASSERT(td, MA_OWNED); 272 if (td->td_priority < curthread->td_priority) 273 curthread->td_flags |= TDF_NEEDRESCHED; 274 } 275 276 /* 277 * This function is called when a thread is about to be put on run queue 278 * because it has been made runnable or its priority has been adjusted. It 279 * determines if the new thread should be immediately preempted to. If so, 280 * it switches to it and eventually returns true. If not, it returns false 281 * so that the caller may place the thread on an appropriate run queue. 282 */ 283 int 284 maybe_preempt(struct thread *td) 285 { 286 #ifdef PREEMPTION 287 struct thread *ctd; 288 int cpri, pri; 289 290 /* 291 * The new thread should not preempt the current thread if any of the 292 * following conditions are true: 293 * 294 * - The kernel is in the throes of crashing (panicstr). 295 * - The current thread has a higher (numerically lower) or 296 * equivalent priority. Note that this prevents curthread from 297 * trying to preempt to itself. 298 * - It is too early in the boot for context switches (cold is set). 299 * - The current thread has an inhibitor set or is in the process of 300 * exiting. In this case, the current thread is about to switch 301 * out anyways, so there's no point in preempting. If we did, 302 * the current thread would not be properly resumed as well, so 303 * just avoid that whole landmine. 304 * - If the new thread's priority is not a realtime priority and 305 * the current thread's priority is not an idle priority and 306 * FULL_PREEMPTION is disabled. 307 * 308 * If all of these conditions are false, but the current thread is in 309 * a nested critical section, then we have to defer the preemption 310 * until we exit the critical section. Otherwise, switch immediately 311 * to the new thread. 312 */ 313 ctd = curthread; 314 THREAD_LOCK_ASSERT(td, MA_OWNED); 315 KASSERT((td->td_inhibitors == 0), 316 ("maybe_preempt: trying to run inhibited thread")); 317 pri = td->td_priority; 318 cpri = ctd->td_priority; 319 if (panicstr != NULL || pri >= cpri || cold /* || dumping */ || 320 TD_IS_INHIBITED(ctd)) 321 return (0); 322 #ifndef FULL_PREEMPTION 323 if (pri > PRI_MAX_ITHD && cpri < PRI_MIN_IDLE) 324 return (0); 325 #endif 326 327 if (ctd->td_critnest > 1) { 328 CTR1(KTR_PROC, "maybe_preempt: in critical section %d", 329 ctd->td_critnest); 330 ctd->td_owepreempt = 1; 331 return (0); 332 } 333 /* 334 * Thread is runnable but not yet put on system run queue. 335 */ 336 MPASS(ctd->td_lock == td->td_lock); 337 MPASS(TD_ON_RUNQ(td)); 338 TD_SET_RUNNING(td); 339 CTR3(KTR_PROC, "preempting to thread %p (pid %d, %s)\n", td, 340 td->td_proc->p_pid, td->td_name); 341 mi_switch(SW_INVOL | SW_PREEMPT | SWT_PREEMPT, td); 342 /* 343 * td's lock pointer may have changed. We have to return with it 344 * locked. 345 */ 346 spinlock_enter(); 347 thread_unlock(ctd); 348 thread_lock(td); 349 spinlock_exit(); 350 return (1); 351 #else 352 return (0); 353 #endif 354 } 355 356 /* 357 * Constants for digital decay and forget: 358 * 90% of (td_estcpu) usage in 5 * loadav time 359 * 95% of (ts_pctcpu) usage in 60 seconds (load insensitive) 360 * Note that, as ps(1) mentions, this can let percentages 361 * total over 100% (I've seen 137.9% for 3 processes). 362 * 363 * Note that schedclock() updates td_estcpu and p_cpticks asynchronously. 364 * 365 * We wish to decay away 90% of td_estcpu in (5 * loadavg) seconds. 366 * That is, the system wants to compute a value of decay such 367 * that the following for loop: 368 * for (i = 0; i < (5 * loadavg); i++) 369 * td_estcpu *= decay; 370 * will compute 371 * td_estcpu *= 0.1; 372 * for all values of loadavg: 373 * 374 * Mathematically this loop can be expressed by saying: 375 * decay ** (5 * loadavg) ~= .1 376 * 377 * The system computes decay as: 378 * decay = (2 * loadavg) / (2 * loadavg + 1) 379 * 380 * We wish to prove that the system's computation of decay 381 * will always fulfill the equation: 382 * decay ** (5 * loadavg) ~= .1 383 * 384 * If we compute b as: 385 * b = 2 * loadavg 386 * then 387 * decay = b / (b + 1) 388 * 389 * We now need to prove two things: 390 * 1) Given factor ** (5 * loadavg) ~= .1, prove factor == b/(b+1) 391 * 2) Given b/(b+1) ** power ~= .1, prove power == (5 * loadavg) 392 * 393 * Facts: 394 * For x close to zero, exp(x) =~ 1 + x, since 395 * exp(x) = 0! + x**1/1! + x**2/2! + ... . 396 * therefore exp(-1/b) =~ 1 - (1/b) = (b-1)/b. 397 * For x close to zero, ln(1+x) =~ x, since 398 * ln(1+x) = x - x**2/2 + x**3/3 - ... -1 < x < 1 399 * therefore ln(b/(b+1)) = ln(1 - 1/(b+1)) =~ -1/(b+1). 400 * ln(.1) =~ -2.30 401 * 402 * Proof of (1): 403 * Solve (factor)**(power) =~ .1 given power (5*loadav): 404 * solving for factor, 405 * ln(factor) =~ (-2.30/5*loadav), or 406 * factor =~ exp(-1/((5/2.30)*loadav)) =~ exp(-1/(2*loadav)) = 407 * exp(-1/b) =~ (b-1)/b =~ b/(b+1). QED 408 * 409 * Proof of (2): 410 * Solve (factor)**(power) =~ .1 given factor == (b/(b+1)): 411 * solving for power, 412 * power*ln(b/(b+1)) =~ -2.30, or 413 * power =~ 2.3 * (b + 1) = 4.6*loadav + 2.3 =~ 5*loadav. QED 414 * 415 * Actual power values for the implemented algorithm are as follows: 416 * loadav: 1 2 3 4 417 * power: 5.68 10.32 14.94 19.55 418 */ 419 420 /* calculations for digital decay to forget 90% of usage in 5*loadav sec */ 421 #define loadfactor(loadav) (2 * (loadav)) 422 #define decay_cpu(loadfac, cpu) (((loadfac) * (cpu)) / ((loadfac) + FSCALE)) 423 424 /* decay 95% of `ts_pctcpu' in 60 seconds; see CCPU_SHIFT before changing */ 425 static fixpt_t ccpu = 0.95122942450071400909 * FSCALE; /* exp(-1/20) */ 426 SYSCTL_INT(_kern, OID_AUTO, ccpu, CTLFLAG_RD, &ccpu, 0, ""); 427 428 /* 429 * If `ccpu' is not equal to `exp(-1/20)' and you still want to use the 430 * faster/more-accurate formula, you'll have to estimate CCPU_SHIFT below 431 * and possibly adjust FSHIFT in "param.h" so that (FSHIFT >= CCPU_SHIFT). 432 * 433 * To estimate CCPU_SHIFT for exp(-1/20), the following formula was used: 434 * 1 - exp(-1/20) ~= 0.0487 ~= 0.0488 == 1 (fixed pt, *11* bits). 435 * 436 * If you don't want to bother with the faster/more-accurate formula, you 437 * can set CCPU_SHIFT to (FSHIFT + 1) which will use a slower/less-accurate 438 * (more general) method of calculating the %age of CPU used by a process. 439 */ 440 #define CCPU_SHIFT 11 441 442 /* 443 * Recompute process priorities, every hz ticks. 444 * MP-safe, called without the Giant mutex. 445 */ 446 /* ARGSUSED */ 447 static void 448 schedcpu(void) 449 { 450 register fixpt_t loadfac = loadfactor(averunnable.ldavg[0]); 451 struct thread *td; 452 struct proc *p; 453 struct td_sched *ts; 454 int awake, realstathz; 455 456 realstathz = stathz ? stathz : hz; 457 sx_slock(&allproc_lock); 458 FOREACH_PROC_IN_SYSTEM(p) { 459 PROC_LOCK(p); 460 if (p->p_state == PRS_NEW) { 461 PROC_UNLOCK(p); 462 continue; 463 } 464 FOREACH_THREAD_IN_PROC(p, td) { 465 awake = 0; 466 thread_lock(td); 467 ts = td->td_sched; 468 /* 469 * Increment sleep time (if sleeping). We 470 * ignore overflow, as above. 471 */ 472 /* 473 * The td_sched slptimes are not touched in wakeup 474 * because the thread may not HAVE everything in 475 * memory? XXX I think this is out of date. 476 */ 477 if (TD_ON_RUNQ(td)) { 478 awake = 1; 479 td->td_flags &= ~TDF_DIDRUN; 480 } else if (TD_IS_RUNNING(td)) { 481 awake = 1; 482 /* Do not clear TDF_DIDRUN */ 483 } else if (td->td_flags & TDF_DIDRUN) { 484 awake = 1; 485 td->td_flags &= ~TDF_DIDRUN; 486 } 487 488 /* 489 * ts_pctcpu is only for ps and ttyinfo(). 490 */ 491 ts->ts_pctcpu = (ts->ts_pctcpu * ccpu) >> FSHIFT; 492 /* 493 * If the td_sched has been idle the entire second, 494 * stop recalculating its priority until 495 * it wakes up. 496 */ 497 if (ts->ts_cpticks != 0) { 498 #if (FSHIFT >= CCPU_SHIFT) 499 ts->ts_pctcpu += (realstathz == 100) 500 ? ((fixpt_t) ts->ts_cpticks) << 501 (FSHIFT - CCPU_SHIFT) : 502 100 * (((fixpt_t) ts->ts_cpticks) 503 << (FSHIFT - CCPU_SHIFT)) / realstathz; 504 #else 505 ts->ts_pctcpu += ((FSCALE - ccpu) * 506 (ts->ts_cpticks * 507 FSCALE / realstathz)) >> FSHIFT; 508 #endif 509 ts->ts_cpticks = 0; 510 } 511 /* 512 * If there are ANY running threads in this process, 513 * then don't count it as sleeping. 514 * XXX: this is broken. 515 */ 516 if (awake) { 517 if (ts->ts_slptime > 1) { 518 /* 519 * In an ideal world, this should not 520 * happen, because whoever woke us 521 * up from the long sleep should have 522 * unwound the slptime and reset our 523 * priority before we run at the stale 524 * priority. Should KASSERT at some 525 * point when all the cases are fixed. 526 */ 527 updatepri(td); 528 } 529 ts->ts_slptime = 0; 530 } else 531 ts->ts_slptime++; 532 if (ts->ts_slptime > 1) { 533 thread_unlock(td); 534 continue; 535 } 536 td->td_estcpu = decay_cpu(loadfac, td->td_estcpu); 537 resetpriority(td); 538 resetpriority_thread(td); 539 thread_unlock(td); 540 } 541 PROC_UNLOCK(p); 542 } 543 sx_sunlock(&allproc_lock); 544 } 545 546 /* 547 * Main loop for a kthread that executes schedcpu once a second. 548 */ 549 static void 550 schedcpu_thread(void) 551 { 552 553 for (;;) { 554 schedcpu(); 555 pause("-", hz); 556 } 557 } 558 559 /* 560 * Recalculate the priority of a process after it has slept for a while. 561 * For all load averages >= 1 and max td_estcpu of 255, sleeping for at 562 * least six times the loadfactor will decay td_estcpu to zero. 563 */ 564 static void 565 updatepri(struct thread *td) 566 { 567 struct td_sched *ts; 568 fixpt_t loadfac; 569 unsigned int newcpu; 570 571 ts = td->td_sched; 572 loadfac = loadfactor(averunnable.ldavg[0]); 573 if (ts->ts_slptime > 5 * loadfac) 574 td->td_estcpu = 0; 575 else { 576 newcpu = td->td_estcpu; 577 ts->ts_slptime--; /* was incremented in schedcpu() */ 578 while (newcpu && --ts->ts_slptime) 579 newcpu = decay_cpu(loadfac, newcpu); 580 td->td_estcpu = newcpu; 581 } 582 } 583 584 /* 585 * Compute the priority of a process when running in user mode. 586 * Arrange to reschedule if the resulting priority is better 587 * than that of the current process. 588 */ 589 static void 590 resetpriority(struct thread *td) 591 { 592 register unsigned int newpriority; 593 594 if (td->td_pri_class == PRI_TIMESHARE) { 595 newpriority = PUSER + td->td_estcpu / INVERSE_ESTCPU_WEIGHT + 596 NICE_WEIGHT * (td->td_proc->p_nice - PRIO_MIN); 597 newpriority = min(max(newpriority, PRI_MIN_TIMESHARE), 598 PRI_MAX_TIMESHARE); 599 sched_user_prio(td, newpriority); 600 } 601 } 602 603 /* 604 * Update the thread's priority when the associated process's user 605 * priority changes. 606 */ 607 static void 608 resetpriority_thread(struct thread *td) 609 { 610 611 /* Only change threads with a time sharing user priority. */ 612 if (td->td_priority < PRI_MIN_TIMESHARE || 613 td->td_priority > PRI_MAX_TIMESHARE) 614 return; 615 616 /* XXX the whole needresched thing is broken, but not silly. */ 617 maybe_resched(td); 618 619 sched_prio(td, td->td_user_pri); 620 } 621 622 /* ARGSUSED */ 623 static void 624 sched_setup(void *dummy) 625 { 626 setup_runqs(); 627 628 if (sched_quantum == 0) 629 sched_quantum = SCHED_QUANTUM; 630 hogticks = 2 * sched_quantum; 631 632 /* Account for thread0. */ 633 sched_load_add(); 634 } 635 636 /* External interfaces start here */ 637 638 /* 639 * Very early in the boot some setup of scheduler-specific 640 * parts of proc0 and of some scheduler resources needs to be done. 641 * Called from: 642 * proc0_init() 643 */ 644 void 645 schedinit(void) 646 { 647 /* 648 * Set up the scheduler specific parts of proc0. 649 */ 650 proc0.p_sched = NULL; /* XXX */ 651 thread0.td_sched = &td_sched0; 652 thread0.td_lock = &sched_lock; 653 mtx_init(&sched_lock, "sched lock", NULL, MTX_SPIN | MTX_RECURSE); 654 } 655 656 int 657 sched_runnable(void) 658 { 659 #ifdef SMP 660 return runq_check(&runq) + runq_check(&runq_pcpu[PCPU_GET(cpuid)]); 661 #else 662 return runq_check(&runq); 663 #endif 664 } 665 666 int 667 sched_rr_interval(void) 668 { 669 if (sched_quantum == 0) 670 sched_quantum = SCHED_QUANTUM; 671 return (sched_quantum); 672 } 673 674 /* 675 * We adjust the priority of the current process. The priority of 676 * a process gets worse as it accumulates CPU time. The cpu usage 677 * estimator (td_estcpu) is increased here. resetpriority() will 678 * compute a different priority each time td_estcpu increases by 679 * INVERSE_ESTCPU_WEIGHT 680 * (until MAXPRI is reached). The cpu usage estimator ramps up 681 * quite quickly when the process is running (linearly), and decays 682 * away exponentially, at a rate which is proportionally slower when 683 * the system is busy. The basic principle is that the system will 684 * 90% forget that the process used a lot of CPU time in 5 * loadav 685 * seconds. This causes the system to favor processes which haven't 686 * run much recently, and to round-robin among other processes. 687 */ 688 void 689 sched_clock(struct thread *td) 690 { 691 struct td_sched *ts; 692 693 THREAD_LOCK_ASSERT(td, MA_OWNED); 694 ts = td->td_sched; 695 696 ts->ts_cpticks++; 697 td->td_estcpu = ESTCPULIM(td->td_estcpu + 1); 698 if ((td->td_estcpu % INVERSE_ESTCPU_WEIGHT) == 0) { 699 resetpriority(td); 700 resetpriority_thread(td); 701 } 702 703 /* 704 * Force a context switch if the current thread has used up a full 705 * quantum (default quantum is 100ms). 706 */ 707 if (!TD_IS_IDLETHREAD(td) && 708 ticks - PCPU_GET(switchticks) >= sched_quantum) 709 td->td_flags |= TDF_NEEDRESCHED; 710 } 711 712 /* 713 * Charge child's scheduling CPU usage to parent. 714 */ 715 void 716 sched_exit(struct proc *p, struct thread *td) 717 { 718 719 KTR_STATE1(KTR_SCHED, "thread", sched_tdname(td), "proc exit", 720 "prio:%d", td->td_priority); 721 722 PROC_LOCK_ASSERT(p, MA_OWNED); 723 sched_exit_thread(FIRST_THREAD_IN_PROC(p), td); 724 } 725 726 void 727 sched_exit_thread(struct thread *td, struct thread *child) 728 { 729 730 KTR_STATE1(KTR_SCHED, "thread", sched_tdname(child), "exit", 731 "prio:%d", child->td_priority); 732 thread_lock(td); 733 td->td_estcpu = ESTCPULIM(td->td_estcpu + child->td_estcpu); 734 thread_unlock(td); 735 thread_lock(child); 736 if ((child->td_flags & TDF_NOLOAD) == 0) 737 sched_load_rem(); 738 thread_unlock(child); 739 } 740 741 void 742 sched_fork(struct thread *td, struct thread *childtd) 743 { 744 sched_fork_thread(td, childtd); 745 } 746 747 void 748 sched_fork_thread(struct thread *td, struct thread *childtd) 749 { 750 struct td_sched *ts; 751 752 childtd->td_estcpu = td->td_estcpu; 753 childtd->td_lock = &sched_lock; 754 childtd->td_cpuset = cpuset_ref(td->td_cpuset); 755 childtd->td_priority = childtd->td_base_pri; 756 ts = childtd->td_sched; 757 bzero(ts, sizeof(*ts)); 758 ts->ts_flags |= (td->td_sched->ts_flags & TSF_AFFINITY); 759 } 760 761 void 762 sched_nice(struct proc *p, int nice) 763 { 764 struct thread *td; 765 766 PROC_LOCK_ASSERT(p, MA_OWNED); 767 p->p_nice = nice; 768 FOREACH_THREAD_IN_PROC(p, td) { 769 thread_lock(td); 770 resetpriority(td); 771 resetpriority_thread(td); 772 thread_unlock(td); 773 } 774 } 775 776 void 777 sched_class(struct thread *td, int class) 778 { 779 THREAD_LOCK_ASSERT(td, MA_OWNED); 780 td->td_pri_class = class; 781 } 782 783 /* 784 * Adjust the priority of a thread. 785 */ 786 static void 787 sched_priority(struct thread *td, u_char prio) 788 { 789 790 791 KTR_POINT3(KTR_SCHED, "thread", sched_tdname(td), "priority change", 792 "prio:%d", td->td_priority, "new prio:%d", prio, KTR_ATTR_LINKED, 793 sched_tdname(curthread)); 794 if (td != curthread && prio > td->td_priority) { 795 KTR_POINT3(KTR_SCHED, "thread", sched_tdname(curthread), 796 "lend prio", "prio:%d", td->td_priority, "new prio:%d", 797 prio, KTR_ATTR_LINKED, sched_tdname(td)); 798 } 799 THREAD_LOCK_ASSERT(td, MA_OWNED); 800 if (td->td_priority == prio) 801 return; 802 td->td_priority = prio; 803 if (TD_ON_RUNQ(td) && td->td_rqindex != (prio / RQ_PPQ)) { 804 sched_rem(td); 805 sched_add(td, SRQ_BORING); 806 } 807 } 808 809 /* 810 * Update a thread's priority when it is lent another thread's 811 * priority. 812 */ 813 void 814 sched_lend_prio(struct thread *td, u_char prio) 815 { 816 817 td->td_flags |= TDF_BORROWING; 818 sched_priority(td, prio); 819 } 820 821 /* 822 * Restore a thread's priority when priority propagation is 823 * over. The prio argument is the minimum priority the thread 824 * needs to have to satisfy other possible priority lending 825 * requests. If the thread's regulary priority is less 826 * important than prio the thread will keep a priority boost 827 * of prio. 828 */ 829 void 830 sched_unlend_prio(struct thread *td, u_char prio) 831 { 832 u_char base_pri; 833 834 if (td->td_base_pri >= PRI_MIN_TIMESHARE && 835 td->td_base_pri <= PRI_MAX_TIMESHARE) 836 base_pri = td->td_user_pri; 837 else 838 base_pri = td->td_base_pri; 839 if (prio >= base_pri) { 840 td->td_flags &= ~TDF_BORROWING; 841 sched_prio(td, base_pri); 842 } else 843 sched_lend_prio(td, prio); 844 } 845 846 void 847 sched_prio(struct thread *td, u_char prio) 848 { 849 u_char oldprio; 850 851 /* First, update the base priority. */ 852 td->td_base_pri = prio; 853 854 /* 855 * If the thread is borrowing another thread's priority, don't ever 856 * lower the priority. 857 */ 858 if (td->td_flags & TDF_BORROWING && td->td_priority < prio) 859 return; 860 861 /* Change the real priority. */ 862 oldprio = td->td_priority; 863 sched_priority(td, prio); 864 865 /* 866 * If the thread is on a turnstile, then let the turnstile update 867 * its state. 868 */ 869 if (TD_ON_LOCK(td) && oldprio != prio) 870 turnstile_adjust(td, oldprio); 871 } 872 873 void 874 sched_user_prio(struct thread *td, u_char prio) 875 { 876 u_char oldprio; 877 878 THREAD_LOCK_ASSERT(td, MA_OWNED); 879 td->td_base_user_pri = prio; 880 if (td->td_flags & TDF_UBORROWING && td->td_user_pri <= prio) 881 return; 882 oldprio = td->td_user_pri; 883 td->td_user_pri = prio; 884 } 885 886 void 887 sched_lend_user_prio(struct thread *td, u_char prio) 888 { 889 u_char oldprio; 890 891 THREAD_LOCK_ASSERT(td, MA_OWNED); 892 td->td_flags |= TDF_UBORROWING; 893 oldprio = td->td_user_pri; 894 td->td_user_pri = prio; 895 } 896 897 void 898 sched_unlend_user_prio(struct thread *td, u_char prio) 899 { 900 u_char base_pri; 901 902 THREAD_LOCK_ASSERT(td, MA_OWNED); 903 base_pri = td->td_base_user_pri; 904 if (prio >= base_pri) { 905 td->td_flags &= ~TDF_UBORROWING; 906 sched_user_prio(td, base_pri); 907 } else { 908 sched_lend_user_prio(td, prio); 909 } 910 } 911 912 void 913 sched_sleep(struct thread *td, int pri) 914 { 915 916 THREAD_LOCK_ASSERT(td, MA_OWNED); 917 td->td_slptick = ticks; 918 td->td_sched->ts_slptime = 0; 919 if (pri) 920 sched_prio(td, pri); 921 if (TD_IS_SUSPENDED(td) || pri >= PSOCK) 922 td->td_flags |= TDF_CANSWAP; 923 } 924 925 void 926 sched_switch(struct thread *td, struct thread *newtd, int flags) 927 { 928 struct mtx *tmtx; 929 struct td_sched *ts; 930 struct proc *p; 931 932 tmtx = NULL; 933 ts = td->td_sched; 934 p = td->td_proc; 935 936 THREAD_LOCK_ASSERT(td, MA_OWNED); 937 938 /* 939 * Switch to the sched lock to fix things up and pick 940 * a new thread. 941 * Block the td_lock in order to avoid breaking the critical path. 942 */ 943 if (td->td_lock != &sched_lock) { 944 mtx_lock_spin(&sched_lock); 945 tmtx = thread_lock_block(td); 946 } 947 948 if ((td->td_flags & TDF_NOLOAD) == 0) 949 sched_load_rem(); 950 951 td->td_lastcpu = td->td_oncpu; 952 if (!(flags & SW_PREEMPT)) 953 td->td_flags &= ~TDF_NEEDRESCHED; 954 td->td_owepreempt = 0; 955 td->td_oncpu = NOCPU; 956 957 /* 958 * At the last moment, if this thread is still marked RUNNING, 959 * then put it back on the run queue as it has not been suspended 960 * or stopped or any thing else similar. We never put the idle 961 * threads on the run queue, however. 962 */ 963 if (td->td_flags & TDF_IDLETD) { 964 TD_SET_CAN_RUN(td); 965 #ifdef SMP 966 idle_cpus_mask &= ~PCPU_GET(cpumask); 967 #endif 968 } else { 969 if (TD_IS_RUNNING(td)) { 970 /* Put us back on the run queue. */ 971 sched_add(td, (flags & SW_PREEMPT) ? 972 SRQ_OURSELF|SRQ_YIELDING|SRQ_PREEMPTED : 973 SRQ_OURSELF|SRQ_YIELDING); 974 } 975 } 976 if (newtd) { 977 /* 978 * The thread we are about to run needs to be counted 979 * as if it had been added to the run queue and selected. 980 * It came from: 981 * * A preemption 982 * * An upcall 983 * * A followon 984 */ 985 KASSERT((newtd->td_inhibitors == 0), 986 ("trying to run inhibited thread")); 987 newtd->td_flags |= TDF_DIDRUN; 988 TD_SET_RUNNING(newtd); 989 if ((newtd->td_flags & TDF_NOLOAD) == 0) 990 sched_load_add(); 991 } else { 992 newtd = choosethread(); 993 MPASS(newtd->td_lock == &sched_lock); 994 } 995 996 if (td != newtd) { 997 #ifdef HWPMC_HOOKS 998 if (PMC_PROC_IS_USING_PMCS(td->td_proc)) 999 PMC_SWITCH_CONTEXT(td, PMC_FN_CSW_OUT); 1000 #endif 1001 /* I feel sleepy */ 1002 lock_profile_release_lock(&sched_lock.lock_object); 1003 #ifdef KDTRACE_HOOKS 1004 /* 1005 * If DTrace has set the active vtime enum to anything 1006 * other than INACTIVE (0), then it should have set the 1007 * function to call. 1008 */ 1009 if (dtrace_vtime_active) 1010 (*dtrace_vtime_switch_func)(newtd); 1011 #endif 1012 1013 cpu_switch(td, newtd, tmtx != NULL ? tmtx : td->td_lock); 1014 lock_profile_obtain_lock_success(&sched_lock.lock_object, 1015 0, 0, __FILE__, __LINE__); 1016 /* 1017 * Where am I? What year is it? 1018 * We are in the same thread that went to sleep above, 1019 * but any amount of time may have passed. All our context 1020 * will still be available as will local variables. 1021 * PCPU values however may have changed as we may have 1022 * changed CPU so don't trust cached values of them. 1023 * New threads will go to fork_exit() instead of here 1024 * so if you change things here you may need to change 1025 * things there too. 1026 * 1027 * If the thread above was exiting it will never wake 1028 * up again here, so either it has saved everything it 1029 * needed to, or the thread_wait() or wait() will 1030 * need to reap it. 1031 */ 1032 #ifdef HWPMC_HOOKS 1033 if (PMC_PROC_IS_USING_PMCS(td->td_proc)) 1034 PMC_SWITCH_CONTEXT(td, PMC_FN_CSW_IN); 1035 #endif 1036 } 1037 1038 #ifdef SMP 1039 if (td->td_flags & TDF_IDLETD) 1040 idle_cpus_mask |= PCPU_GET(cpumask); 1041 #endif 1042 sched_lock.mtx_lock = (uintptr_t)td; 1043 td->td_oncpu = PCPU_GET(cpuid); 1044 MPASS(td->td_lock == &sched_lock); 1045 } 1046 1047 void 1048 sched_wakeup(struct thread *td) 1049 { 1050 struct td_sched *ts; 1051 1052 THREAD_LOCK_ASSERT(td, MA_OWNED); 1053 ts = td->td_sched; 1054 td->td_flags &= ~TDF_CANSWAP; 1055 if (ts->ts_slptime > 1) { 1056 updatepri(td); 1057 resetpriority(td); 1058 } 1059 td->td_slptick = 0; 1060 ts->ts_slptime = 0; 1061 sched_add(td, SRQ_BORING); 1062 } 1063 1064 #ifdef SMP 1065 static int 1066 forward_wakeup(int cpunum) 1067 { 1068 struct pcpu *pc; 1069 cpumask_t dontuse, id, map, map2, map3, me; 1070 1071 mtx_assert(&sched_lock, MA_OWNED); 1072 1073 CTR0(KTR_RUNQ, "forward_wakeup()"); 1074 1075 if ((!forward_wakeup_enabled) || 1076 (forward_wakeup_use_mask == 0 && forward_wakeup_use_loop == 0)) 1077 return (0); 1078 if (!smp_started || cold || panicstr) 1079 return (0); 1080 1081 forward_wakeups_requested++; 1082 1083 /* 1084 * Check the idle mask we received against what we calculated 1085 * before in the old version. 1086 */ 1087 me = PCPU_GET(cpumask); 1088 1089 /* Don't bother if we should be doing it ourself. */ 1090 if ((me & idle_cpus_mask) && (cpunum == NOCPU || me == (1 << cpunum))) 1091 return (0); 1092 1093 dontuse = me | stopped_cpus | hlt_cpus_mask; 1094 map3 = 0; 1095 if (forward_wakeup_use_loop) { 1096 SLIST_FOREACH(pc, &cpuhead, pc_allcpu) { 1097 id = pc->pc_cpumask; 1098 if ((id & dontuse) == 0 && 1099 pc->pc_curthread == pc->pc_idlethread) { 1100 map3 |= id; 1101 } 1102 } 1103 } 1104 1105 if (forward_wakeup_use_mask) { 1106 map = 0; 1107 map = idle_cpus_mask & ~dontuse; 1108 1109 /* If they are both on, compare and use loop if different. */ 1110 if (forward_wakeup_use_loop) { 1111 if (map != map3) { 1112 printf("map (%02X) != map3 (%02X)\n", map, 1113 map3); 1114 map = map3; 1115 } 1116 } 1117 } else { 1118 map = map3; 1119 } 1120 1121 /* If we only allow a specific CPU, then mask off all the others. */ 1122 if (cpunum != NOCPU) { 1123 KASSERT((cpunum <= mp_maxcpus),("forward_wakeup: bad cpunum.")); 1124 map &= (1 << cpunum); 1125 } else { 1126 /* Try choose an idle die. */ 1127 if (forward_wakeup_use_htt) { 1128 map2 = (map & (map >> 1)) & 0x5555; 1129 if (map2) { 1130 map = map2; 1131 } 1132 } 1133 1134 /* Set only one bit. */ 1135 if (forward_wakeup_use_single) { 1136 map = map & ((~map) + 1); 1137 } 1138 } 1139 if (map) { 1140 forward_wakeups_delivered++; 1141 ipi_selected(map, IPI_AST); 1142 return (1); 1143 } 1144 if (cpunum == NOCPU) 1145 printf("forward_wakeup: Idle processor not found\n"); 1146 return (0); 1147 } 1148 1149 static void 1150 kick_other_cpu(int pri, int cpuid) 1151 { 1152 struct pcpu *pcpu; 1153 int cpri; 1154 1155 pcpu = pcpu_find(cpuid); 1156 if (idle_cpus_mask & pcpu->pc_cpumask) { 1157 forward_wakeups_delivered++; 1158 ipi_cpu(cpuid, IPI_AST); 1159 return; 1160 } 1161 1162 cpri = pcpu->pc_curthread->td_priority; 1163 if (pri >= cpri) 1164 return; 1165 1166 #if defined(IPI_PREEMPTION) && defined(PREEMPTION) 1167 #if !defined(FULL_PREEMPTION) 1168 if (pri <= PRI_MAX_ITHD) 1169 #endif /* ! FULL_PREEMPTION */ 1170 { 1171 ipi_cpu(cpuid, IPI_PREEMPT); 1172 return; 1173 } 1174 #endif /* defined(IPI_PREEMPTION) && defined(PREEMPTION) */ 1175 1176 pcpu->pc_curthread->td_flags |= TDF_NEEDRESCHED; 1177 ipi_cpu(cpuid, IPI_AST); 1178 return; 1179 } 1180 #endif /* SMP */ 1181 1182 #ifdef SMP 1183 static int 1184 sched_pickcpu(struct thread *td) 1185 { 1186 int best, cpu; 1187 1188 mtx_assert(&sched_lock, MA_OWNED); 1189 1190 if (THREAD_CAN_SCHED(td, td->td_lastcpu)) 1191 best = td->td_lastcpu; 1192 else 1193 best = NOCPU; 1194 CPU_FOREACH(cpu) { 1195 if (!THREAD_CAN_SCHED(td, cpu)) 1196 continue; 1197 1198 if (best == NOCPU) 1199 best = cpu; 1200 else if (runq_length[cpu] < runq_length[best]) 1201 best = cpu; 1202 } 1203 KASSERT(best != NOCPU, ("no valid CPUs")); 1204 1205 return (best); 1206 } 1207 #endif 1208 1209 void 1210 sched_add(struct thread *td, int flags) 1211 #ifdef SMP 1212 { 1213 struct td_sched *ts; 1214 int forwarded = 0; 1215 int cpu; 1216 int single_cpu = 0; 1217 1218 ts = td->td_sched; 1219 THREAD_LOCK_ASSERT(td, MA_OWNED); 1220 KASSERT((td->td_inhibitors == 0), 1221 ("sched_add: trying to run inhibited thread")); 1222 KASSERT((TD_CAN_RUN(td) || TD_IS_RUNNING(td)), 1223 ("sched_add: bad thread state")); 1224 KASSERT(td->td_flags & TDF_INMEM, 1225 ("sched_add: thread swapped out")); 1226 1227 KTR_STATE2(KTR_SCHED, "thread", sched_tdname(td), "runq add", 1228 "prio:%d", td->td_priority, KTR_ATTR_LINKED, 1229 sched_tdname(curthread)); 1230 KTR_POINT1(KTR_SCHED, "thread", sched_tdname(curthread), "wokeup", 1231 KTR_ATTR_LINKED, sched_tdname(td)); 1232 1233 1234 /* 1235 * Now that the thread is moving to the run-queue, set the lock 1236 * to the scheduler's lock. 1237 */ 1238 if (td->td_lock != &sched_lock) { 1239 mtx_lock_spin(&sched_lock); 1240 thread_lock_set(td, &sched_lock); 1241 } 1242 TD_SET_RUNQ(td); 1243 1244 /* 1245 * If SMP is started and the thread is pinned or otherwise limited to 1246 * a specific set of CPUs, queue the thread to a per-CPU run queue. 1247 * Otherwise, queue the thread to the global run queue. 1248 * 1249 * If SMP has not yet been started we must use the global run queue 1250 * as per-CPU state may not be initialized yet and we may crash if we 1251 * try to access the per-CPU run queues. 1252 */ 1253 if (smp_started && (td->td_pinned != 0 || td->td_flags & TDF_BOUND || 1254 ts->ts_flags & TSF_AFFINITY)) { 1255 if (td->td_pinned != 0) 1256 cpu = td->td_lastcpu; 1257 else if (td->td_flags & TDF_BOUND) { 1258 /* Find CPU from bound runq. */ 1259 KASSERT(SKE_RUNQ_PCPU(ts), 1260 ("sched_add: bound td_sched not on cpu runq")); 1261 cpu = ts->ts_runq - &runq_pcpu[0]; 1262 } else 1263 /* Find a valid CPU for our cpuset */ 1264 cpu = sched_pickcpu(td); 1265 ts->ts_runq = &runq_pcpu[cpu]; 1266 single_cpu = 1; 1267 CTR3(KTR_RUNQ, 1268 "sched_add: Put td_sched:%p(td:%p) on cpu%d runq", ts, td, 1269 cpu); 1270 } else { 1271 CTR2(KTR_RUNQ, 1272 "sched_add: adding td_sched:%p (td:%p) to gbl runq", ts, 1273 td); 1274 cpu = NOCPU; 1275 ts->ts_runq = &runq; 1276 } 1277 1278 if (single_cpu && (cpu != PCPU_GET(cpuid))) { 1279 kick_other_cpu(td->td_priority, cpu); 1280 } else { 1281 if (!single_cpu) { 1282 cpumask_t me = PCPU_GET(cpumask); 1283 cpumask_t idle = idle_cpus_mask & me; 1284 1285 if (!idle && ((flags & SRQ_INTR) == 0) && 1286 (idle_cpus_mask & ~(hlt_cpus_mask | me))) 1287 forwarded = forward_wakeup(cpu); 1288 } 1289 1290 if (!forwarded) { 1291 if ((flags & SRQ_YIELDING) == 0 && maybe_preempt(td)) 1292 return; 1293 else 1294 maybe_resched(td); 1295 } 1296 } 1297 1298 if ((td->td_flags & TDF_NOLOAD) == 0) 1299 sched_load_add(); 1300 runq_add(ts->ts_runq, td, flags); 1301 if (cpu != NOCPU) 1302 runq_length[cpu]++; 1303 } 1304 #else /* SMP */ 1305 { 1306 struct td_sched *ts; 1307 1308 ts = td->td_sched; 1309 THREAD_LOCK_ASSERT(td, MA_OWNED); 1310 KASSERT((td->td_inhibitors == 0), 1311 ("sched_add: trying to run inhibited thread")); 1312 KASSERT((TD_CAN_RUN(td) || TD_IS_RUNNING(td)), 1313 ("sched_add: bad thread state")); 1314 KASSERT(td->td_flags & TDF_INMEM, 1315 ("sched_add: thread swapped out")); 1316 KTR_STATE2(KTR_SCHED, "thread", sched_tdname(td), "runq add", 1317 "prio:%d", td->td_priority, KTR_ATTR_LINKED, 1318 sched_tdname(curthread)); 1319 KTR_POINT1(KTR_SCHED, "thread", sched_tdname(curthread), "wokeup", 1320 KTR_ATTR_LINKED, sched_tdname(td)); 1321 1322 /* 1323 * Now that the thread is moving to the run-queue, set the lock 1324 * to the scheduler's lock. 1325 */ 1326 if (td->td_lock != &sched_lock) { 1327 mtx_lock_spin(&sched_lock); 1328 thread_lock_set(td, &sched_lock); 1329 } 1330 TD_SET_RUNQ(td); 1331 CTR2(KTR_RUNQ, "sched_add: adding td_sched:%p (td:%p) to runq", ts, td); 1332 ts->ts_runq = &runq; 1333 1334 /* 1335 * If we are yielding (on the way out anyhow) or the thread 1336 * being saved is US, then don't try be smart about preemption 1337 * or kicking off another CPU as it won't help and may hinder. 1338 * In the YIEDLING case, we are about to run whoever is being 1339 * put in the queue anyhow, and in the OURSELF case, we are 1340 * puting ourself on the run queue which also only happens 1341 * when we are about to yield. 1342 */ 1343 if ((flags & SRQ_YIELDING) == 0) { 1344 if (maybe_preempt(td)) 1345 return; 1346 } 1347 if ((td->td_flags & TDF_NOLOAD) == 0) 1348 sched_load_add(); 1349 runq_add(ts->ts_runq, td, flags); 1350 maybe_resched(td); 1351 } 1352 #endif /* SMP */ 1353 1354 void 1355 sched_rem(struct thread *td) 1356 { 1357 struct td_sched *ts; 1358 1359 ts = td->td_sched; 1360 KASSERT(td->td_flags & TDF_INMEM, 1361 ("sched_rem: thread swapped out")); 1362 KASSERT(TD_ON_RUNQ(td), 1363 ("sched_rem: thread not on run queue")); 1364 mtx_assert(&sched_lock, MA_OWNED); 1365 KTR_STATE2(KTR_SCHED, "thread", sched_tdname(td), "runq rem", 1366 "prio:%d", td->td_priority, KTR_ATTR_LINKED, 1367 sched_tdname(curthread)); 1368 1369 if ((td->td_flags & TDF_NOLOAD) == 0) 1370 sched_load_rem(); 1371 #ifdef SMP 1372 if (ts->ts_runq != &runq) 1373 runq_length[ts->ts_runq - runq_pcpu]--; 1374 #endif 1375 runq_remove(ts->ts_runq, td); 1376 TD_SET_CAN_RUN(td); 1377 } 1378 1379 /* 1380 * Select threads to run. Note that running threads still consume a 1381 * slot. 1382 */ 1383 struct thread * 1384 sched_choose(void) 1385 { 1386 struct thread *td; 1387 struct runq *rq; 1388 1389 mtx_assert(&sched_lock, MA_OWNED); 1390 #ifdef SMP 1391 struct thread *tdcpu; 1392 1393 rq = &runq; 1394 td = runq_choose_fuzz(&runq, runq_fuzz); 1395 tdcpu = runq_choose(&runq_pcpu[PCPU_GET(cpuid)]); 1396 1397 if (td == NULL || 1398 (tdcpu != NULL && 1399 tdcpu->td_priority < td->td_priority)) { 1400 CTR2(KTR_RUNQ, "choosing td %p from pcpu runq %d", tdcpu, 1401 PCPU_GET(cpuid)); 1402 td = tdcpu; 1403 rq = &runq_pcpu[PCPU_GET(cpuid)]; 1404 } else { 1405 CTR1(KTR_RUNQ, "choosing td_sched %p from main runq", td); 1406 } 1407 1408 #else 1409 rq = &runq; 1410 td = runq_choose(&runq); 1411 #endif 1412 1413 if (td) { 1414 #ifdef SMP 1415 if (td == tdcpu) 1416 runq_length[PCPU_GET(cpuid)]--; 1417 #endif 1418 runq_remove(rq, td); 1419 td->td_flags |= TDF_DIDRUN; 1420 1421 KASSERT(td->td_flags & TDF_INMEM, 1422 ("sched_choose: thread swapped out")); 1423 return (td); 1424 } 1425 return (PCPU_GET(idlethread)); 1426 } 1427 1428 void 1429 sched_preempt(struct thread *td) 1430 { 1431 thread_lock(td); 1432 if (td->td_critnest > 1) 1433 td->td_owepreempt = 1; 1434 else 1435 mi_switch(SW_INVOL | SW_PREEMPT | SWT_PREEMPT, NULL); 1436 thread_unlock(td); 1437 } 1438 1439 void 1440 sched_userret(struct thread *td) 1441 { 1442 /* 1443 * XXX we cheat slightly on the locking here to avoid locking in 1444 * the usual case. Setting td_priority here is essentially an 1445 * incomplete workaround for not setting it properly elsewhere. 1446 * Now that some interrupt handlers are threads, not setting it 1447 * properly elsewhere can clobber it in the window between setting 1448 * it here and returning to user mode, so don't waste time setting 1449 * it perfectly here. 1450 */ 1451 KASSERT((td->td_flags & TDF_BORROWING) == 0, 1452 ("thread with borrowed priority returning to userland")); 1453 if (td->td_priority != td->td_user_pri) { 1454 thread_lock(td); 1455 td->td_priority = td->td_user_pri; 1456 td->td_base_pri = td->td_user_pri; 1457 thread_unlock(td); 1458 } 1459 } 1460 1461 void 1462 sched_bind(struct thread *td, int cpu) 1463 { 1464 struct td_sched *ts; 1465 1466 THREAD_LOCK_ASSERT(td, MA_OWNED|MA_NOTRECURSED); 1467 KASSERT(td == curthread, ("sched_bind: can only bind curthread")); 1468 1469 ts = td->td_sched; 1470 1471 td->td_flags |= TDF_BOUND; 1472 #ifdef SMP 1473 ts->ts_runq = &runq_pcpu[cpu]; 1474 if (PCPU_GET(cpuid) == cpu) 1475 return; 1476 1477 mi_switch(SW_VOL, NULL); 1478 #endif 1479 } 1480 1481 void 1482 sched_unbind(struct thread* td) 1483 { 1484 THREAD_LOCK_ASSERT(td, MA_OWNED); 1485 KASSERT(td == curthread, ("sched_unbind: can only bind curthread")); 1486 td->td_flags &= ~TDF_BOUND; 1487 } 1488 1489 int 1490 sched_is_bound(struct thread *td) 1491 { 1492 THREAD_LOCK_ASSERT(td, MA_OWNED); 1493 return (td->td_flags & TDF_BOUND); 1494 } 1495 1496 void 1497 sched_relinquish(struct thread *td) 1498 { 1499 thread_lock(td); 1500 mi_switch(SW_VOL | SWT_RELINQUISH, NULL); 1501 thread_unlock(td); 1502 } 1503 1504 int 1505 sched_load(void) 1506 { 1507 return (sched_tdcnt); 1508 } 1509 1510 int 1511 sched_sizeof_proc(void) 1512 { 1513 return (sizeof(struct proc)); 1514 } 1515 1516 int 1517 sched_sizeof_thread(void) 1518 { 1519 return (sizeof(struct thread) + sizeof(struct td_sched)); 1520 } 1521 1522 fixpt_t 1523 sched_pctcpu(struct thread *td) 1524 { 1525 struct td_sched *ts; 1526 1527 THREAD_LOCK_ASSERT(td, MA_OWNED); 1528 ts = td->td_sched; 1529 return (ts->ts_pctcpu); 1530 } 1531 1532 void 1533 sched_tick(void) 1534 { 1535 } 1536 1537 /* 1538 * The actual idle process. 1539 */ 1540 void 1541 sched_idletd(void *dummy) 1542 { 1543 1544 for (;;) { 1545 mtx_assert(&Giant, MA_NOTOWNED); 1546 1547 while (sched_runnable() == 0) 1548 cpu_idle(0); 1549 1550 mtx_lock_spin(&sched_lock); 1551 mi_switch(SW_VOL | SWT_IDLE, NULL); 1552 mtx_unlock_spin(&sched_lock); 1553 } 1554 } 1555 1556 /* 1557 * A CPU is entering for the first time or a thread is exiting. 1558 */ 1559 void 1560 sched_throw(struct thread *td) 1561 { 1562 /* 1563 * Correct spinlock nesting. The idle thread context that we are 1564 * borrowing was created so that it would start out with a single 1565 * spin lock (sched_lock) held in fork_trampoline(). Since we've 1566 * explicitly acquired locks in this function, the nesting count 1567 * is now 2 rather than 1. Since we are nested, calling 1568 * spinlock_exit() will simply adjust the counts without allowing 1569 * spin lock using code to interrupt us. 1570 */ 1571 if (td == NULL) { 1572 mtx_lock_spin(&sched_lock); 1573 spinlock_exit(); 1574 PCPU_SET(switchtime, cpu_ticks()); 1575 PCPU_SET(switchticks, ticks); 1576 } else { 1577 lock_profile_release_lock(&sched_lock.lock_object); 1578 MPASS(td->td_lock == &sched_lock); 1579 } 1580 mtx_assert(&sched_lock, MA_OWNED); 1581 KASSERT(curthread->td_md.md_spinlock_count == 1, ("invalid count")); 1582 cpu_throw(td, choosethread()); /* doesn't return */ 1583 } 1584 1585 void 1586 sched_fork_exit(struct thread *td) 1587 { 1588 1589 /* 1590 * Finish setting up thread glue so that it begins execution in a 1591 * non-nested critical section with sched_lock held but not recursed. 1592 */ 1593 td->td_oncpu = PCPU_GET(cpuid); 1594 sched_lock.mtx_lock = (uintptr_t)td; 1595 lock_profile_obtain_lock_success(&sched_lock.lock_object, 1596 0, 0, __FILE__, __LINE__); 1597 THREAD_LOCK_ASSERT(td, MA_OWNED | MA_NOTRECURSED); 1598 } 1599 1600 char * 1601 sched_tdname(struct thread *td) 1602 { 1603 #ifdef KTR 1604 struct td_sched *ts; 1605 1606 ts = td->td_sched; 1607 if (ts->ts_name[0] == '\0') 1608 snprintf(ts->ts_name, sizeof(ts->ts_name), 1609 "%s tid %d", td->td_name, td->td_tid); 1610 return (ts->ts_name); 1611 #else 1612 return (td->td_name); 1613 #endif 1614 } 1615 1616 void 1617 sched_affinity(struct thread *td) 1618 { 1619 #ifdef SMP 1620 struct td_sched *ts; 1621 int cpu; 1622 1623 THREAD_LOCK_ASSERT(td, MA_OWNED); 1624 1625 /* 1626 * Set the TSF_AFFINITY flag if there is at least one CPU this 1627 * thread can't run on. 1628 */ 1629 ts = td->td_sched; 1630 ts->ts_flags &= ~TSF_AFFINITY; 1631 CPU_FOREACH(cpu) { 1632 if (!THREAD_CAN_SCHED(td, cpu)) { 1633 ts->ts_flags |= TSF_AFFINITY; 1634 break; 1635 } 1636 } 1637 1638 /* 1639 * If this thread can run on all CPUs, nothing else to do. 1640 */ 1641 if (!(ts->ts_flags & TSF_AFFINITY)) 1642 return; 1643 1644 /* Pinned threads and bound threads should be left alone. */ 1645 if (td->td_pinned != 0 || td->td_flags & TDF_BOUND) 1646 return; 1647 1648 switch (td->td_state) { 1649 case TDS_RUNQ: 1650 /* 1651 * If we are on a per-CPU runqueue that is in the set, 1652 * then nothing needs to be done. 1653 */ 1654 if (ts->ts_runq != &runq && 1655 THREAD_CAN_SCHED(td, ts->ts_runq - runq_pcpu)) 1656 return; 1657 1658 /* Put this thread on a valid per-CPU runqueue. */ 1659 sched_rem(td); 1660 sched_add(td, SRQ_BORING); 1661 break; 1662 case TDS_RUNNING: 1663 /* 1664 * See if our current CPU is in the set. If not, force a 1665 * context switch. 1666 */ 1667 if (THREAD_CAN_SCHED(td, td->td_oncpu)) 1668 return; 1669 1670 td->td_flags |= TDF_NEEDRESCHED; 1671 if (td != curthread) 1672 ipi_cpu(cpu, IPI_AST); 1673 break; 1674 default: 1675 break; 1676 } 1677 #endif 1678 }
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