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/9.1/sys/kern/sched_4bsd.c 236344 2012-05-30 23:22:52Z rstone $"); 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/sdt.h> 54 #include <sys/smp.h> 55 #include <sys/sysctl.h> 56 #include <sys/sx.h> 57 #include <sys/turnstile.h> 58 #include <sys/umtx.h> 59 #include <machine/pcb.h> 60 #include <machine/smp.h> 61 62 #ifdef HWPMC_HOOKS 63 #include <sys/pmckern.h> 64 #endif 65 66 #ifdef KDTRACE_HOOKS 67 #include <sys/dtrace_bsd.h> 68 int dtrace_vtime_active; 69 dtrace_vtime_switch_func_t dtrace_vtime_switch_func; 70 #endif 71 72 /* 73 * INVERSE_ESTCPU_WEIGHT is only suitable for statclock() frequencies in 74 * the range 100-256 Hz (approximately). 75 */ 76 #define ESTCPULIM(e) \ 77 min((e), INVERSE_ESTCPU_WEIGHT * (NICE_WEIGHT * (PRIO_MAX - PRIO_MIN) - \ 78 RQ_PPQ) + INVERSE_ESTCPU_WEIGHT - 1) 79 #ifdef SMP 80 #define INVERSE_ESTCPU_WEIGHT (8 * smp_cpus) 81 #else 82 #define INVERSE_ESTCPU_WEIGHT 8 /* 1 / (priorities per estcpu level). */ 83 #endif 84 #define NICE_WEIGHT 1 /* Priorities per nice level. */ 85 86 #define TS_NAME_LEN (MAXCOMLEN + sizeof(" td ") + sizeof(__XSTRING(UINT_MAX))) 87 88 /* 89 * The schedulable entity that runs a context. 90 * This is an extension to the thread structure and is tailored to 91 * the requirements of this scheduler 92 */ 93 struct td_sched { 94 fixpt_t ts_pctcpu; /* (j) %cpu during p_swtime. */ 95 int ts_cpticks; /* (j) Ticks of cpu time. */ 96 int ts_slptime; /* (j) Seconds !RUNNING. */ 97 int ts_flags; 98 struct runq *ts_runq; /* runq the thread is currently on */ 99 #ifdef KTR 100 char ts_name[TS_NAME_LEN]; 101 #endif 102 }; 103 104 /* flags kept in td_flags */ 105 #define TDF_DIDRUN TDF_SCHED0 /* thread actually ran. */ 106 #define TDF_BOUND TDF_SCHED1 /* Bound to one CPU. */ 107 108 /* flags kept in ts_flags */ 109 #define TSF_AFFINITY 0x0001 /* Has a non-"full" CPU set. */ 110 111 #define SKE_RUNQ_PCPU(ts) \ 112 ((ts)->ts_runq != 0 && (ts)->ts_runq != &runq) 113 114 #define THREAD_CAN_SCHED(td, cpu) \ 115 CPU_ISSET((cpu), &(td)->td_cpuset->cs_mask) 116 117 static struct td_sched td_sched0; 118 struct mtx sched_lock; 119 120 static int sched_tdcnt; /* Total runnable threads in the system. */ 121 static int sched_quantum; /* Roundrobin scheduling quantum in ticks. */ 122 #define SCHED_QUANTUM (hz / 10) /* Default sched quantum */ 123 124 static void setup_runqs(void); 125 static void schedcpu(void); 126 static void schedcpu_thread(void); 127 static void sched_priority(struct thread *td, u_char prio); 128 static void sched_setup(void *dummy); 129 static void maybe_resched(struct thread *td); 130 static void updatepri(struct thread *td); 131 static void resetpriority(struct thread *td); 132 static void resetpriority_thread(struct thread *td); 133 #ifdef SMP 134 static int sched_pickcpu(struct thread *td); 135 static int forward_wakeup(int cpunum); 136 static void kick_other_cpu(int pri, int cpuid); 137 #endif 138 139 static struct kproc_desc sched_kp = { 140 "schedcpu", 141 schedcpu_thread, 142 NULL 143 }; 144 SYSINIT(schedcpu, SI_SUB_RUN_SCHEDULER, SI_ORDER_FIRST, kproc_start, 145 &sched_kp); 146 SYSINIT(sched_setup, SI_SUB_RUN_QUEUE, SI_ORDER_FIRST, sched_setup, NULL); 147 148 /* 149 * Global run queue. 150 */ 151 static struct runq runq; 152 153 #ifdef SMP 154 /* 155 * Per-CPU run queues 156 */ 157 static struct runq runq_pcpu[MAXCPU]; 158 long runq_length[MAXCPU]; 159 160 static cpuset_t idle_cpus_mask; 161 #endif 162 163 struct pcpuidlestat { 164 u_int idlecalls; 165 u_int oldidlecalls; 166 }; 167 static DPCPU_DEFINE(struct pcpuidlestat, idlestat); 168 169 static void 170 setup_runqs(void) 171 { 172 #ifdef SMP 173 int i; 174 175 for (i = 0; i < MAXCPU; ++i) 176 runq_init(&runq_pcpu[i]); 177 #endif 178 179 runq_init(&runq); 180 } 181 182 static int 183 sysctl_kern_quantum(SYSCTL_HANDLER_ARGS) 184 { 185 int error, new_val; 186 187 new_val = sched_quantum * tick; 188 error = sysctl_handle_int(oidp, &new_val, 0, req); 189 if (error != 0 || req->newptr == NULL) 190 return (error); 191 if (new_val < tick) 192 return (EINVAL); 193 sched_quantum = new_val / tick; 194 hogticks = 2 * sched_quantum; 195 return (0); 196 } 197 198 SYSCTL_NODE(_kern, OID_AUTO, sched, CTLFLAG_RD, 0, "Scheduler"); 199 200 SYSCTL_STRING(_kern_sched, OID_AUTO, name, CTLFLAG_RD, "4BSD", 0, 201 "Scheduler name"); 202 203 SYSCTL_PROC(_kern_sched, OID_AUTO, quantum, CTLTYPE_INT | CTLFLAG_RW, 204 0, sizeof sched_quantum, sysctl_kern_quantum, "I", 205 "Roundrobin scheduling quantum in microseconds"); 206 207 #ifdef SMP 208 /* Enable forwarding of wakeups to all other cpus */ 209 SYSCTL_NODE(_kern_sched, OID_AUTO, ipiwakeup, CTLFLAG_RD, NULL, "Kernel SMP"); 210 211 static int runq_fuzz = 1; 212 SYSCTL_INT(_kern_sched, OID_AUTO, runq_fuzz, CTLFLAG_RW, &runq_fuzz, 0, ""); 213 214 static int forward_wakeup_enabled = 1; 215 SYSCTL_INT(_kern_sched_ipiwakeup, OID_AUTO, enabled, CTLFLAG_RW, 216 &forward_wakeup_enabled, 0, 217 "Forwarding of wakeup to idle CPUs"); 218 219 static int forward_wakeups_requested = 0; 220 SYSCTL_INT(_kern_sched_ipiwakeup, OID_AUTO, requested, CTLFLAG_RD, 221 &forward_wakeups_requested, 0, 222 "Requests for Forwarding of wakeup to idle CPUs"); 223 224 static int forward_wakeups_delivered = 0; 225 SYSCTL_INT(_kern_sched_ipiwakeup, OID_AUTO, delivered, CTLFLAG_RD, 226 &forward_wakeups_delivered, 0, 227 "Completed Forwarding of wakeup to idle CPUs"); 228 229 static int forward_wakeup_use_mask = 1; 230 SYSCTL_INT(_kern_sched_ipiwakeup, OID_AUTO, usemask, CTLFLAG_RW, 231 &forward_wakeup_use_mask, 0, 232 "Use the mask of idle cpus"); 233 234 static int forward_wakeup_use_loop = 0; 235 SYSCTL_INT(_kern_sched_ipiwakeup, OID_AUTO, useloop, CTLFLAG_RW, 236 &forward_wakeup_use_loop, 0, 237 "Use a loop to find idle cpus"); 238 239 #endif 240 #if 0 241 static int sched_followon = 0; 242 SYSCTL_INT(_kern_sched, OID_AUTO, followon, CTLFLAG_RW, 243 &sched_followon, 0, 244 "allow threads to share a quantum"); 245 #endif 246 247 SDT_PROVIDER_DEFINE(sched); 248 249 SDT_PROBE_DEFINE3(sched, , , change_pri, change-pri, "struct thread *", 250 "struct proc *", "uint8_t"); 251 SDT_PROBE_DEFINE3(sched, , , dequeue, dequeue, "struct thread *", 252 "struct proc *", "void *"); 253 SDT_PROBE_DEFINE4(sched, , , enqueue, enqueue, "struct thread *", 254 "struct proc *", "void *", "int"); 255 SDT_PROBE_DEFINE4(sched, , , lend_pri, lend-pri, "struct thread *", 256 "struct proc *", "uint8_t", "struct thread *"); 257 SDT_PROBE_DEFINE2(sched, , , load_change, load-change, "int", "int"); 258 SDT_PROBE_DEFINE2(sched, , , off_cpu, off-cpu, "struct thread *", 259 "struct proc *"); 260 SDT_PROBE_DEFINE(sched, , , on_cpu, on-cpu); 261 SDT_PROBE_DEFINE(sched, , , remain_cpu, remain-cpu); 262 SDT_PROBE_DEFINE2(sched, , , surrender, surrender, "struct thread *", 263 "struct proc *"); 264 265 static __inline void 266 sched_load_add(void) 267 { 268 269 sched_tdcnt++; 270 KTR_COUNTER0(KTR_SCHED, "load", "global load", sched_tdcnt); 271 SDT_PROBE2(sched, , , load_change, NOCPU, sched_tdcnt); 272 } 273 274 static __inline void 275 sched_load_rem(void) 276 { 277 278 sched_tdcnt--; 279 KTR_COUNTER0(KTR_SCHED, "load", "global load", sched_tdcnt); 280 SDT_PROBE2(sched, , , load_change, NOCPU, sched_tdcnt); 281 } 282 /* 283 * Arrange to reschedule if necessary, taking the priorities and 284 * schedulers into account. 285 */ 286 static void 287 maybe_resched(struct thread *td) 288 { 289 290 THREAD_LOCK_ASSERT(td, MA_OWNED); 291 if (td->td_priority < curthread->td_priority) 292 curthread->td_flags |= TDF_NEEDRESCHED; 293 } 294 295 /* 296 * This function is called when a thread is about to be put on run queue 297 * because it has been made runnable or its priority has been adjusted. It 298 * determines if the new thread should be immediately preempted to. If so, 299 * it switches to it and eventually returns true. If not, it returns false 300 * so that the caller may place the thread on an appropriate run queue. 301 */ 302 int 303 maybe_preempt(struct thread *td) 304 { 305 #ifdef PREEMPTION 306 struct thread *ctd; 307 int cpri, pri; 308 309 /* 310 * The new thread should not preempt the current thread if any of the 311 * following conditions are true: 312 * 313 * - The kernel is in the throes of crashing (panicstr). 314 * - The current thread has a higher (numerically lower) or 315 * equivalent priority. Note that this prevents curthread from 316 * trying to preempt to itself. 317 * - It is too early in the boot for context switches (cold is set). 318 * - The current thread has an inhibitor set or is in the process of 319 * exiting. In this case, the current thread is about to switch 320 * out anyways, so there's no point in preempting. If we did, 321 * the current thread would not be properly resumed as well, so 322 * just avoid that whole landmine. 323 * - If the new thread's priority is not a realtime priority and 324 * the current thread's priority is not an idle priority and 325 * FULL_PREEMPTION is disabled. 326 * 327 * If all of these conditions are false, but the current thread is in 328 * a nested critical section, then we have to defer the preemption 329 * until we exit the critical section. Otherwise, switch immediately 330 * to the new thread. 331 */ 332 ctd = curthread; 333 THREAD_LOCK_ASSERT(td, MA_OWNED); 334 KASSERT((td->td_inhibitors == 0), 335 ("maybe_preempt: trying to run inhibited thread")); 336 pri = td->td_priority; 337 cpri = ctd->td_priority; 338 if (panicstr != NULL || pri >= cpri || cold /* || dumping */ || 339 TD_IS_INHIBITED(ctd)) 340 return (0); 341 #ifndef FULL_PREEMPTION 342 if (pri > PRI_MAX_ITHD && cpri < PRI_MIN_IDLE) 343 return (0); 344 #endif 345 346 if (ctd->td_critnest > 1) { 347 CTR1(KTR_PROC, "maybe_preempt: in critical section %d", 348 ctd->td_critnest); 349 ctd->td_owepreempt = 1; 350 return (0); 351 } 352 /* 353 * Thread is runnable but not yet put on system run queue. 354 */ 355 MPASS(ctd->td_lock == td->td_lock); 356 MPASS(TD_ON_RUNQ(td)); 357 TD_SET_RUNNING(td); 358 CTR3(KTR_PROC, "preempting to thread %p (pid %d, %s)\n", td, 359 td->td_proc->p_pid, td->td_name); 360 mi_switch(SW_INVOL | SW_PREEMPT | SWT_PREEMPT, td); 361 /* 362 * td's lock pointer may have changed. We have to return with it 363 * locked. 364 */ 365 spinlock_enter(); 366 thread_unlock(ctd); 367 thread_lock(td); 368 spinlock_exit(); 369 return (1); 370 #else 371 return (0); 372 #endif 373 } 374 375 /* 376 * Constants for digital decay and forget: 377 * 90% of (td_estcpu) usage in 5 * loadav time 378 * 95% of (ts_pctcpu) usage in 60 seconds (load insensitive) 379 * Note that, as ps(1) mentions, this can let percentages 380 * total over 100% (I've seen 137.9% for 3 processes). 381 * 382 * Note that schedclock() updates td_estcpu and p_cpticks asynchronously. 383 * 384 * We wish to decay away 90% of td_estcpu in (5 * loadavg) seconds. 385 * That is, the system wants to compute a value of decay such 386 * that the following for loop: 387 * for (i = 0; i < (5 * loadavg); i++) 388 * td_estcpu *= decay; 389 * will compute 390 * td_estcpu *= 0.1; 391 * for all values of loadavg: 392 * 393 * Mathematically this loop can be expressed by saying: 394 * decay ** (5 * loadavg) ~= .1 395 * 396 * The system computes decay as: 397 * decay = (2 * loadavg) / (2 * loadavg + 1) 398 * 399 * We wish to prove that the system's computation of decay 400 * will always fulfill the equation: 401 * decay ** (5 * loadavg) ~= .1 402 * 403 * If we compute b as: 404 * b = 2 * loadavg 405 * then 406 * decay = b / (b + 1) 407 * 408 * We now need to prove two things: 409 * 1) Given factor ** (5 * loadavg) ~= .1, prove factor == b/(b+1) 410 * 2) Given b/(b+1) ** power ~= .1, prove power == (5 * loadavg) 411 * 412 * Facts: 413 * For x close to zero, exp(x) =~ 1 + x, since 414 * exp(x) = 0! + x**1/1! + x**2/2! + ... . 415 * therefore exp(-1/b) =~ 1 - (1/b) = (b-1)/b. 416 * For x close to zero, ln(1+x) =~ x, since 417 * ln(1+x) = x - x**2/2 + x**3/3 - ... -1 < x < 1 418 * therefore ln(b/(b+1)) = ln(1 - 1/(b+1)) =~ -1/(b+1). 419 * ln(.1) =~ -2.30 420 * 421 * Proof of (1): 422 * Solve (factor)**(power) =~ .1 given power (5*loadav): 423 * solving for factor, 424 * ln(factor) =~ (-2.30/5*loadav), or 425 * factor =~ exp(-1/((5/2.30)*loadav)) =~ exp(-1/(2*loadav)) = 426 * exp(-1/b) =~ (b-1)/b =~ b/(b+1). QED 427 * 428 * Proof of (2): 429 * Solve (factor)**(power) =~ .1 given factor == (b/(b+1)): 430 * solving for power, 431 * power*ln(b/(b+1)) =~ -2.30, or 432 * power =~ 2.3 * (b + 1) = 4.6*loadav + 2.3 =~ 5*loadav. QED 433 * 434 * Actual power values for the implemented algorithm are as follows: 435 * loadav: 1 2 3 4 436 * power: 5.68 10.32 14.94 19.55 437 */ 438 439 /* calculations for digital decay to forget 90% of usage in 5*loadav sec */ 440 #define loadfactor(loadav) (2 * (loadav)) 441 #define decay_cpu(loadfac, cpu) (((loadfac) * (cpu)) / ((loadfac) + FSCALE)) 442 443 /* decay 95% of `ts_pctcpu' in 60 seconds; see CCPU_SHIFT before changing */ 444 static fixpt_t ccpu = 0.95122942450071400909 * FSCALE; /* exp(-1/20) */ 445 SYSCTL_UINT(_kern, OID_AUTO, ccpu, CTLFLAG_RD, &ccpu, 0, ""); 446 447 /* 448 * If `ccpu' is not equal to `exp(-1/20)' and you still want to use the 449 * faster/more-accurate formula, you'll have to estimate CCPU_SHIFT below 450 * and possibly adjust FSHIFT in "param.h" so that (FSHIFT >= CCPU_SHIFT). 451 * 452 * To estimate CCPU_SHIFT for exp(-1/20), the following formula was used: 453 * 1 - exp(-1/20) ~= 0.0487 ~= 0.0488 == 1 (fixed pt, *11* bits). 454 * 455 * If you don't want to bother with the faster/more-accurate formula, you 456 * can set CCPU_SHIFT to (FSHIFT + 1) which will use a slower/less-accurate 457 * (more general) method of calculating the %age of CPU used by a process. 458 */ 459 #define CCPU_SHIFT 11 460 461 /* 462 * Recompute process priorities, every hz ticks. 463 * MP-safe, called without the Giant mutex. 464 */ 465 /* ARGSUSED */ 466 static void 467 schedcpu(void) 468 { 469 register fixpt_t loadfac = loadfactor(averunnable.ldavg[0]); 470 struct thread *td; 471 struct proc *p; 472 struct td_sched *ts; 473 int awake, realstathz; 474 475 realstathz = stathz ? stathz : hz; 476 sx_slock(&allproc_lock); 477 FOREACH_PROC_IN_SYSTEM(p) { 478 PROC_LOCK(p); 479 if (p->p_state == PRS_NEW) { 480 PROC_UNLOCK(p); 481 continue; 482 } 483 FOREACH_THREAD_IN_PROC(p, td) { 484 awake = 0; 485 thread_lock(td); 486 ts = td->td_sched; 487 /* 488 * Increment sleep time (if sleeping). We 489 * ignore overflow, as above. 490 */ 491 /* 492 * The td_sched slptimes are not touched in wakeup 493 * because the thread may not HAVE everything in 494 * memory? XXX I think this is out of date. 495 */ 496 if (TD_ON_RUNQ(td)) { 497 awake = 1; 498 td->td_flags &= ~TDF_DIDRUN; 499 } else if (TD_IS_RUNNING(td)) { 500 awake = 1; 501 /* Do not clear TDF_DIDRUN */ 502 } else if (td->td_flags & TDF_DIDRUN) { 503 awake = 1; 504 td->td_flags &= ~TDF_DIDRUN; 505 } 506 507 /* 508 * ts_pctcpu is only for ps and ttyinfo(). 509 */ 510 ts->ts_pctcpu = (ts->ts_pctcpu * ccpu) >> FSHIFT; 511 /* 512 * If the td_sched has been idle the entire second, 513 * stop recalculating its priority until 514 * it wakes up. 515 */ 516 if (ts->ts_cpticks != 0) { 517 #if (FSHIFT >= CCPU_SHIFT) 518 ts->ts_pctcpu += (realstathz == 100) 519 ? ((fixpt_t) ts->ts_cpticks) << 520 (FSHIFT - CCPU_SHIFT) : 521 100 * (((fixpt_t) ts->ts_cpticks) 522 << (FSHIFT - CCPU_SHIFT)) / realstathz; 523 #else 524 ts->ts_pctcpu += ((FSCALE - ccpu) * 525 (ts->ts_cpticks * 526 FSCALE / realstathz)) >> FSHIFT; 527 #endif 528 ts->ts_cpticks = 0; 529 } 530 /* 531 * If there are ANY running threads in this process, 532 * then don't count it as sleeping. 533 * XXX: this is broken. 534 */ 535 if (awake) { 536 if (ts->ts_slptime > 1) { 537 /* 538 * In an ideal world, this should not 539 * happen, because whoever woke us 540 * up from the long sleep should have 541 * unwound the slptime and reset our 542 * priority before we run at the stale 543 * priority. Should KASSERT at some 544 * point when all the cases are fixed. 545 */ 546 updatepri(td); 547 } 548 ts->ts_slptime = 0; 549 } else 550 ts->ts_slptime++; 551 if (ts->ts_slptime > 1) { 552 thread_unlock(td); 553 continue; 554 } 555 td->td_estcpu = decay_cpu(loadfac, td->td_estcpu); 556 resetpriority(td); 557 resetpriority_thread(td); 558 thread_unlock(td); 559 } 560 PROC_UNLOCK(p); 561 } 562 sx_sunlock(&allproc_lock); 563 } 564 565 /* 566 * Main loop for a kthread that executes schedcpu once a second. 567 */ 568 static void 569 schedcpu_thread(void) 570 { 571 572 for (;;) { 573 schedcpu(); 574 pause("-", hz); 575 } 576 } 577 578 /* 579 * Recalculate the priority of a process after it has slept for a while. 580 * For all load averages >= 1 and max td_estcpu of 255, sleeping for at 581 * least six times the loadfactor will decay td_estcpu to zero. 582 */ 583 static void 584 updatepri(struct thread *td) 585 { 586 struct td_sched *ts; 587 fixpt_t loadfac; 588 unsigned int newcpu; 589 590 ts = td->td_sched; 591 loadfac = loadfactor(averunnable.ldavg[0]); 592 if (ts->ts_slptime > 5 * loadfac) 593 td->td_estcpu = 0; 594 else { 595 newcpu = td->td_estcpu; 596 ts->ts_slptime--; /* was incremented in schedcpu() */ 597 while (newcpu && --ts->ts_slptime) 598 newcpu = decay_cpu(loadfac, newcpu); 599 td->td_estcpu = newcpu; 600 } 601 } 602 603 /* 604 * Compute the priority of a process when running in user mode. 605 * Arrange to reschedule if the resulting priority is better 606 * than that of the current process. 607 */ 608 static void 609 resetpriority(struct thread *td) 610 { 611 register unsigned int newpriority; 612 613 if (td->td_pri_class == PRI_TIMESHARE) { 614 newpriority = PUSER + td->td_estcpu / INVERSE_ESTCPU_WEIGHT + 615 NICE_WEIGHT * (td->td_proc->p_nice - PRIO_MIN); 616 newpriority = min(max(newpriority, PRI_MIN_TIMESHARE), 617 PRI_MAX_TIMESHARE); 618 sched_user_prio(td, newpriority); 619 } 620 } 621 622 /* 623 * Update the thread's priority when the associated process's user 624 * priority changes. 625 */ 626 static void 627 resetpriority_thread(struct thread *td) 628 { 629 630 /* Only change threads with a time sharing user priority. */ 631 if (td->td_priority < PRI_MIN_TIMESHARE || 632 td->td_priority > PRI_MAX_TIMESHARE) 633 return; 634 635 /* XXX the whole needresched thing is broken, but not silly. */ 636 maybe_resched(td); 637 638 sched_prio(td, td->td_user_pri); 639 } 640 641 /* ARGSUSED */ 642 static void 643 sched_setup(void *dummy) 644 { 645 setup_runqs(); 646 647 if (sched_quantum == 0) 648 sched_quantum = SCHED_QUANTUM; 649 hogticks = 2 * sched_quantum; 650 651 /* Account for thread0. */ 652 sched_load_add(); 653 } 654 655 /* External interfaces start here */ 656 657 /* 658 * Very early in the boot some setup of scheduler-specific 659 * parts of proc0 and of some scheduler resources needs to be done. 660 * Called from: 661 * proc0_init() 662 */ 663 void 664 schedinit(void) 665 { 666 /* 667 * Set up the scheduler specific parts of proc0. 668 */ 669 proc0.p_sched = NULL; /* XXX */ 670 thread0.td_sched = &td_sched0; 671 thread0.td_lock = &sched_lock; 672 mtx_init(&sched_lock, "sched lock", NULL, MTX_SPIN | MTX_RECURSE); 673 } 674 675 int 676 sched_runnable(void) 677 { 678 #ifdef SMP 679 return runq_check(&runq) + runq_check(&runq_pcpu[PCPU_GET(cpuid)]); 680 #else 681 return runq_check(&runq); 682 #endif 683 } 684 685 int 686 sched_rr_interval(void) 687 { 688 if (sched_quantum == 0) 689 sched_quantum = SCHED_QUANTUM; 690 return (sched_quantum); 691 } 692 693 /* 694 * We adjust the priority of the current process. The priority of 695 * a process gets worse as it accumulates CPU time. The cpu usage 696 * estimator (td_estcpu) is increased here. resetpriority() will 697 * compute a different priority each time td_estcpu increases by 698 * INVERSE_ESTCPU_WEIGHT 699 * (until MAXPRI is reached). The cpu usage estimator ramps up 700 * quite quickly when the process is running (linearly), and decays 701 * away exponentially, at a rate which is proportionally slower when 702 * the system is busy. The basic principle is that the system will 703 * 90% forget that the process used a lot of CPU time in 5 * loadav 704 * seconds. This causes the system to favor processes which haven't 705 * run much recently, and to round-robin among other processes. 706 */ 707 void 708 sched_clock(struct thread *td) 709 { 710 struct pcpuidlestat *stat; 711 struct td_sched *ts; 712 713 THREAD_LOCK_ASSERT(td, MA_OWNED); 714 ts = td->td_sched; 715 716 ts->ts_cpticks++; 717 td->td_estcpu = ESTCPULIM(td->td_estcpu + 1); 718 if ((td->td_estcpu % INVERSE_ESTCPU_WEIGHT) == 0) { 719 resetpriority(td); 720 resetpriority_thread(td); 721 } 722 723 /* 724 * Force a context switch if the current thread has used up a full 725 * quantum (default quantum is 100ms). 726 */ 727 if (!TD_IS_IDLETHREAD(td) && 728 ticks - PCPU_GET(switchticks) >= sched_quantum) 729 td->td_flags |= TDF_NEEDRESCHED; 730 731 stat = DPCPU_PTR(idlestat); 732 stat->oldidlecalls = stat->idlecalls; 733 stat->idlecalls = 0; 734 } 735 736 /* 737 * Charge child's scheduling CPU usage to parent. 738 */ 739 void 740 sched_exit(struct proc *p, struct thread *td) 741 { 742 743 KTR_STATE1(KTR_SCHED, "thread", sched_tdname(td), "proc exit", 744 "prio:%d", td->td_priority); 745 746 PROC_LOCK_ASSERT(p, MA_OWNED); 747 sched_exit_thread(FIRST_THREAD_IN_PROC(p), td); 748 } 749 750 void 751 sched_exit_thread(struct thread *td, struct thread *child) 752 { 753 754 KTR_STATE1(KTR_SCHED, "thread", sched_tdname(child), "exit", 755 "prio:%d", child->td_priority); 756 thread_lock(td); 757 td->td_estcpu = ESTCPULIM(td->td_estcpu + child->td_estcpu); 758 thread_unlock(td); 759 thread_lock(child); 760 if ((child->td_flags & TDF_NOLOAD) == 0) 761 sched_load_rem(); 762 thread_unlock(child); 763 } 764 765 void 766 sched_fork(struct thread *td, struct thread *childtd) 767 { 768 sched_fork_thread(td, childtd); 769 } 770 771 void 772 sched_fork_thread(struct thread *td, struct thread *childtd) 773 { 774 struct td_sched *ts; 775 776 childtd->td_estcpu = td->td_estcpu; 777 childtd->td_lock = &sched_lock; 778 childtd->td_cpuset = cpuset_ref(td->td_cpuset); 779 childtd->td_priority = childtd->td_base_pri; 780 ts = childtd->td_sched; 781 bzero(ts, sizeof(*ts)); 782 ts->ts_flags |= (td->td_sched->ts_flags & TSF_AFFINITY); 783 } 784 785 void 786 sched_nice(struct proc *p, int nice) 787 { 788 struct thread *td; 789 790 PROC_LOCK_ASSERT(p, MA_OWNED); 791 p->p_nice = nice; 792 FOREACH_THREAD_IN_PROC(p, td) { 793 thread_lock(td); 794 resetpriority(td); 795 resetpriority_thread(td); 796 thread_unlock(td); 797 } 798 } 799 800 void 801 sched_class(struct thread *td, int class) 802 { 803 THREAD_LOCK_ASSERT(td, MA_OWNED); 804 td->td_pri_class = class; 805 } 806 807 /* 808 * Adjust the priority of a thread. 809 */ 810 static void 811 sched_priority(struct thread *td, u_char prio) 812 { 813 814 815 KTR_POINT3(KTR_SCHED, "thread", sched_tdname(td), "priority change", 816 "prio:%d", td->td_priority, "new prio:%d", prio, KTR_ATTR_LINKED, 817 sched_tdname(curthread)); 818 SDT_PROBE3(sched, , , change_pri, td, td->td_proc, prio); 819 if (td != curthread && prio > td->td_priority) { 820 KTR_POINT3(KTR_SCHED, "thread", sched_tdname(curthread), 821 "lend prio", "prio:%d", td->td_priority, "new prio:%d", 822 prio, KTR_ATTR_LINKED, sched_tdname(td)); 823 SDT_PROBE4(sched, , , lend_pri, td, td->td_proc, prio, 824 curthread); 825 } 826 THREAD_LOCK_ASSERT(td, MA_OWNED); 827 if (td->td_priority == prio) 828 return; 829 td->td_priority = prio; 830 if (TD_ON_RUNQ(td) && td->td_rqindex != (prio / RQ_PPQ)) { 831 sched_rem(td); 832 sched_add(td, SRQ_BORING); 833 } 834 } 835 836 /* 837 * Update a thread's priority when it is lent another thread's 838 * priority. 839 */ 840 void 841 sched_lend_prio(struct thread *td, u_char prio) 842 { 843 844 td->td_flags |= TDF_BORROWING; 845 sched_priority(td, prio); 846 } 847 848 /* 849 * Restore a thread's priority when priority propagation is 850 * over. The prio argument is the minimum priority the thread 851 * needs to have to satisfy other possible priority lending 852 * requests. If the thread's regulary priority is less 853 * important than prio the thread will keep a priority boost 854 * of prio. 855 */ 856 void 857 sched_unlend_prio(struct thread *td, u_char prio) 858 { 859 u_char base_pri; 860 861 if (td->td_base_pri >= PRI_MIN_TIMESHARE && 862 td->td_base_pri <= PRI_MAX_TIMESHARE) 863 base_pri = td->td_user_pri; 864 else 865 base_pri = td->td_base_pri; 866 if (prio >= base_pri) { 867 td->td_flags &= ~TDF_BORROWING; 868 sched_prio(td, base_pri); 869 } else 870 sched_lend_prio(td, prio); 871 } 872 873 void 874 sched_prio(struct thread *td, u_char prio) 875 { 876 u_char oldprio; 877 878 /* First, update the base priority. */ 879 td->td_base_pri = prio; 880 881 /* 882 * If the thread is borrowing another thread's priority, don't ever 883 * lower the priority. 884 */ 885 if (td->td_flags & TDF_BORROWING && td->td_priority < prio) 886 return; 887 888 /* Change the real priority. */ 889 oldprio = td->td_priority; 890 sched_priority(td, prio); 891 892 /* 893 * If the thread is on a turnstile, then let the turnstile update 894 * its state. 895 */ 896 if (TD_ON_LOCK(td) && oldprio != prio) 897 turnstile_adjust(td, oldprio); 898 } 899 900 void 901 sched_user_prio(struct thread *td, u_char prio) 902 { 903 904 THREAD_LOCK_ASSERT(td, MA_OWNED); 905 td->td_base_user_pri = prio; 906 if (td->td_lend_user_pri <= prio) 907 return; 908 td->td_user_pri = prio; 909 } 910 911 void 912 sched_lend_user_prio(struct thread *td, u_char prio) 913 { 914 915 THREAD_LOCK_ASSERT(td, MA_OWNED); 916 td->td_lend_user_pri = prio; 917 td->td_user_pri = min(prio, td->td_base_user_pri); 918 if (td->td_priority > td->td_user_pri) 919 sched_prio(td, td->td_user_pri); 920 else if (td->td_priority != td->td_user_pri) 921 td->td_flags |= TDF_NEEDRESCHED; 922 } 923 924 void 925 sched_sleep(struct thread *td, int pri) 926 { 927 928 THREAD_LOCK_ASSERT(td, MA_OWNED); 929 td->td_slptick = ticks; 930 td->td_sched->ts_slptime = 0; 931 if (pri != 0 && PRI_BASE(td->td_pri_class) == PRI_TIMESHARE) 932 sched_prio(td, pri); 933 if (TD_IS_SUSPENDED(td) || pri >= PSOCK) 934 td->td_flags |= TDF_CANSWAP; 935 } 936 937 void 938 sched_switch(struct thread *td, struct thread *newtd, int flags) 939 { 940 struct mtx *tmtx; 941 struct td_sched *ts; 942 struct proc *p; 943 944 tmtx = NULL; 945 ts = td->td_sched; 946 p = td->td_proc; 947 948 THREAD_LOCK_ASSERT(td, MA_OWNED); 949 950 /* 951 * Switch to the sched lock to fix things up and pick 952 * a new thread. 953 * Block the td_lock in order to avoid breaking the critical path. 954 */ 955 if (td->td_lock != &sched_lock) { 956 mtx_lock_spin(&sched_lock); 957 tmtx = thread_lock_block(td); 958 } 959 960 if ((td->td_flags & TDF_NOLOAD) == 0) 961 sched_load_rem(); 962 963 td->td_lastcpu = td->td_oncpu; 964 if (!(flags & SW_PREEMPT)) 965 td->td_flags &= ~TDF_NEEDRESCHED; 966 td->td_owepreempt = 0; 967 td->td_oncpu = NOCPU; 968 969 /* 970 * At the last moment, if this thread is still marked RUNNING, 971 * then put it back on the run queue as it has not been suspended 972 * or stopped or any thing else similar. We never put the idle 973 * threads on the run queue, however. 974 */ 975 if (td->td_flags & TDF_IDLETD) { 976 TD_SET_CAN_RUN(td); 977 #ifdef SMP 978 CPU_CLR(PCPU_GET(cpuid), &idle_cpus_mask); 979 #endif 980 } else { 981 if (TD_IS_RUNNING(td)) { 982 /* Put us back on the run queue. */ 983 sched_add(td, (flags & SW_PREEMPT) ? 984 SRQ_OURSELF|SRQ_YIELDING|SRQ_PREEMPTED : 985 SRQ_OURSELF|SRQ_YIELDING); 986 } 987 } 988 if (newtd) { 989 /* 990 * The thread we are about to run needs to be counted 991 * as if it had been added to the run queue and selected. 992 * It came from: 993 * * A preemption 994 * * An upcall 995 * * A followon 996 */ 997 KASSERT((newtd->td_inhibitors == 0), 998 ("trying to run inhibited thread")); 999 newtd->td_flags |= TDF_DIDRUN; 1000 TD_SET_RUNNING(newtd); 1001 if ((newtd->td_flags & TDF_NOLOAD) == 0) 1002 sched_load_add(); 1003 } else { 1004 newtd = choosethread(); 1005 MPASS(newtd->td_lock == &sched_lock); 1006 } 1007 1008 if (td != newtd) { 1009 #ifdef HWPMC_HOOKS 1010 if (PMC_PROC_IS_USING_PMCS(td->td_proc)) 1011 PMC_SWITCH_CONTEXT(td, PMC_FN_CSW_OUT); 1012 #endif 1013 1014 SDT_PROBE2(sched, , , off_cpu, td, td->td_proc); 1015 1016 /* I feel sleepy */ 1017 lock_profile_release_lock(&sched_lock.lock_object); 1018 #ifdef KDTRACE_HOOKS 1019 /* 1020 * If DTrace has set the active vtime enum to anything 1021 * other than INACTIVE (0), then it should have set the 1022 * function to call. 1023 */ 1024 if (dtrace_vtime_active) 1025 (*dtrace_vtime_switch_func)(newtd); 1026 #endif 1027 1028 cpu_switch(td, newtd, tmtx != NULL ? tmtx : td->td_lock); 1029 lock_profile_obtain_lock_success(&sched_lock.lock_object, 1030 0, 0, __FILE__, __LINE__); 1031 /* 1032 * Where am I? What year is it? 1033 * We are in the same thread that went to sleep above, 1034 * but any amount of time may have passed. All our context 1035 * will still be available as will local variables. 1036 * PCPU values however may have changed as we may have 1037 * changed CPU so don't trust cached values of them. 1038 * New threads will go to fork_exit() instead of here 1039 * so if you change things here you may need to change 1040 * things there too. 1041 * 1042 * If the thread above was exiting it will never wake 1043 * up again here, so either it has saved everything it 1044 * needed to, or the thread_wait() or wait() will 1045 * need to reap it. 1046 */ 1047 1048 SDT_PROBE0(sched, , , on_cpu); 1049 #ifdef HWPMC_HOOKS 1050 if (PMC_PROC_IS_USING_PMCS(td->td_proc)) 1051 PMC_SWITCH_CONTEXT(td, PMC_FN_CSW_IN); 1052 #endif 1053 } else 1054 SDT_PROBE0(sched, , , remain_cpu); 1055 1056 #ifdef SMP 1057 if (td->td_flags & TDF_IDLETD) 1058 CPU_SET(PCPU_GET(cpuid), &idle_cpus_mask); 1059 #endif 1060 sched_lock.mtx_lock = (uintptr_t)td; 1061 td->td_oncpu = PCPU_GET(cpuid); 1062 MPASS(td->td_lock == &sched_lock); 1063 } 1064 1065 void 1066 sched_wakeup(struct thread *td) 1067 { 1068 struct td_sched *ts; 1069 1070 THREAD_LOCK_ASSERT(td, MA_OWNED); 1071 ts = td->td_sched; 1072 td->td_flags &= ~TDF_CANSWAP; 1073 if (ts->ts_slptime > 1) { 1074 updatepri(td); 1075 resetpriority(td); 1076 } 1077 td->td_slptick = 0; 1078 ts->ts_slptime = 0; 1079 sched_add(td, SRQ_BORING); 1080 } 1081 1082 #ifdef SMP 1083 static int 1084 forward_wakeup(int cpunum) 1085 { 1086 struct pcpu *pc; 1087 cpuset_t dontuse, map, map2; 1088 u_int id, me; 1089 int iscpuset; 1090 1091 mtx_assert(&sched_lock, MA_OWNED); 1092 1093 CTR0(KTR_RUNQ, "forward_wakeup()"); 1094 1095 if ((!forward_wakeup_enabled) || 1096 (forward_wakeup_use_mask == 0 && forward_wakeup_use_loop == 0)) 1097 return (0); 1098 if (!smp_started || cold || panicstr) 1099 return (0); 1100 1101 forward_wakeups_requested++; 1102 1103 /* 1104 * Check the idle mask we received against what we calculated 1105 * before in the old version. 1106 */ 1107 me = PCPU_GET(cpuid); 1108 1109 /* Don't bother if we should be doing it ourself. */ 1110 if (CPU_ISSET(me, &idle_cpus_mask) && 1111 (cpunum == NOCPU || me == cpunum)) 1112 return (0); 1113 1114 CPU_SETOF(me, &dontuse); 1115 CPU_OR(&dontuse, &stopped_cpus); 1116 CPU_OR(&dontuse, &hlt_cpus_mask); 1117 CPU_ZERO(&map2); 1118 if (forward_wakeup_use_loop) { 1119 STAILQ_FOREACH(pc, &cpuhead, pc_allcpu) { 1120 id = pc->pc_cpuid; 1121 if (!CPU_ISSET(id, &dontuse) && 1122 pc->pc_curthread == pc->pc_idlethread) { 1123 CPU_SET(id, &map2); 1124 } 1125 } 1126 } 1127 1128 if (forward_wakeup_use_mask) { 1129 map = idle_cpus_mask; 1130 CPU_NAND(&map, &dontuse); 1131 1132 /* If they are both on, compare and use loop if different. */ 1133 if (forward_wakeup_use_loop) { 1134 if (CPU_CMP(&map, &map2)) { 1135 printf("map != map2, loop method preferred\n"); 1136 map = map2; 1137 } 1138 } 1139 } else { 1140 map = map2; 1141 } 1142 1143 /* If we only allow a specific CPU, then mask off all the others. */ 1144 if (cpunum != NOCPU) { 1145 KASSERT((cpunum <= mp_maxcpus),("forward_wakeup: bad cpunum.")); 1146 iscpuset = CPU_ISSET(cpunum, &map); 1147 if (iscpuset == 0) 1148 CPU_ZERO(&map); 1149 else 1150 CPU_SETOF(cpunum, &map); 1151 } 1152 if (!CPU_EMPTY(&map)) { 1153 forward_wakeups_delivered++; 1154 STAILQ_FOREACH(pc, &cpuhead, pc_allcpu) { 1155 id = pc->pc_cpuid; 1156 if (!CPU_ISSET(id, &map)) 1157 continue; 1158 if (cpu_idle_wakeup(pc->pc_cpuid)) 1159 CPU_CLR(id, &map); 1160 } 1161 if (!CPU_EMPTY(&map)) 1162 ipi_selected(map, IPI_AST); 1163 return (1); 1164 } 1165 if (cpunum == NOCPU) 1166 printf("forward_wakeup: Idle processor not found\n"); 1167 return (0); 1168 } 1169 1170 static void 1171 kick_other_cpu(int pri, int cpuid) 1172 { 1173 struct pcpu *pcpu; 1174 int cpri; 1175 1176 pcpu = pcpu_find(cpuid); 1177 if (CPU_ISSET(cpuid, &idle_cpus_mask)) { 1178 forward_wakeups_delivered++; 1179 if (!cpu_idle_wakeup(cpuid)) 1180 ipi_cpu(cpuid, IPI_AST); 1181 return; 1182 } 1183 1184 cpri = pcpu->pc_curthread->td_priority; 1185 if (pri >= cpri) 1186 return; 1187 1188 #if defined(IPI_PREEMPTION) && defined(PREEMPTION) 1189 #if !defined(FULL_PREEMPTION) 1190 if (pri <= PRI_MAX_ITHD) 1191 #endif /* ! FULL_PREEMPTION */ 1192 { 1193 ipi_cpu(cpuid, IPI_PREEMPT); 1194 return; 1195 } 1196 #endif /* defined(IPI_PREEMPTION) && defined(PREEMPTION) */ 1197 1198 pcpu->pc_curthread->td_flags |= TDF_NEEDRESCHED; 1199 ipi_cpu(cpuid, IPI_AST); 1200 return; 1201 } 1202 #endif /* SMP */ 1203 1204 #ifdef SMP 1205 static int 1206 sched_pickcpu(struct thread *td) 1207 { 1208 int best, cpu; 1209 1210 mtx_assert(&sched_lock, MA_OWNED); 1211 1212 if (THREAD_CAN_SCHED(td, td->td_lastcpu)) 1213 best = td->td_lastcpu; 1214 else 1215 best = NOCPU; 1216 CPU_FOREACH(cpu) { 1217 if (!THREAD_CAN_SCHED(td, cpu)) 1218 continue; 1219 1220 if (best == NOCPU) 1221 best = cpu; 1222 else if (runq_length[cpu] < runq_length[best]) 1223 best = cpu; 1224 } 1225 KASSERT(best != NOCPU, ("no valid CPUs")); 1226 1227 return (best); 1228 } 1229 #endif 1230 1231 void 1232 sched_add(struct thread *td, int flags) 1233 #ifdef SMP 1234 { 1235 cpuset_t tidlemsk; 1236 struct td_sched *ts; 1237 u_int cpu, cpuid; 1238 int forwarded = 0; 1239 int single_cpu = 0; 1240 1241 ts = td->td_sched; 1242 THREAD_LOCK_ASSERT(td, MA_OWNED); 1243 KASSERT((td->td_inhibitors == 0), 1244 ("sched_add: trying to run inhibited thread")); 1245 KASSERT((TD_CAN_RUN(td) || TD_IS_RUNNING(td)), 1246 ("sched_add: bad thread state")); 1247 KASSERT(td->td_flags & TDF_INMEM, 1248 ("sched_add: thread swapped out")); 1249 1250 KTR_STATE2(KTR_SCHED, "thread", sched_tdname(td), "runq add", 1251 "prio:%d", td->td_priority, KTR_ATTR_LINKED, 1252 sched_tdname(curthread)); 1253 KTR_POINT1(KTR_SCHED, "thread", sched_tdname(curthread), "wokeup", 1254 KTR_ATTR_LINKED, sched_tdname(td)); 1255 SDT_PROBE4(sched, , , enqueue, td, td->td_proc, NULL, 1256 flags & SRQ_PREEMPTED); 1257 1258 1259 /* 1260 * Now that the thread is moving to the run-queue, set the lock 1261 * to the scheduler's lock. 1262 */ 1263 if (td->td_lock != &sched_lock) { 1264 mtx_lock_spin(&sched_lock); 1265 thread_lock_set(td, &sched_lock); 1266 } 1267 TD_SET_RUNQ(td); 1268 1269 /* 1270 * If SMP is started and the thread is pinned or otherwise limited to 1271 * a specific set of CPUs, queue the thread to a per-CPU run queue. 1272 * Otherwise, queue the thread to the global run queue. 1273 * 1274 * If SMP has not yet been started we must use the global run queue 1275 * as per-CPU state may not be initialized yet and we may crash if we 1276 * try to access the per-CPU run queues. 1277 */ 1278 if (smp_started && (td->td_pinned != 0 || td->td_flags & TDF_BOUND || 1279 ts->ts_flags & TSF_AFFINITY)) { 1280 if (td->td_pinned != 0) 1281 cpu = td->td_lastcpu; 1282 else if (td->td_flags & TDF_BOUND) { 1283 /* Find CPU from bound runq. */ 1284 KASSERT(SKE_RUNQ_PCPU(ts), 1285 ("sched_add: bound td_sched not on cpu runq")); 1286 cpu = ts->ts_runq - &runq_pcpu[0]; 1287 } else 1288 /* Find a valid CPU for our cpuset */ 1289 cpu = sched_pickcpu(td); 1290 ts->ts_runq = &runq_pcpu[cpu]; 1291 single_cpu = 1; 1292 CTR3(KTR_RUNQ, 1293 "sched_add: Put td_sched:%p(td:%p) on cpu%d runq", ts, td, 1294 cpu); 1295 } else { 1296 CTR2(KTR_RUNQ, 1297 "sched_add: adding td_sched:%p (td:%p) to gbl runq", ts, 1298 td); 1299 cpu = NOCPU; 1300 ts->ts_runq = &runq; 1301 } 1302 1303 cpuid = PCPU_GET(cpuid); 1304 if (single_cpu && cpu != cpuid) { 1305 kick_other_cpu(td->td_priority, cpu); 1306 } else { 1307 if (!single_cpu) { 1308 tidlemsk = idle_cpus_mask; 1309 CPU_NAND(&tidlemsk, &hlt_cpus_mask); 1310 CPU_CLR(cpuid, &tidlemsk); 1311 1312 if (!CPU_ISSET(cpuid, &idle_cpus_mask) && 1313 ((flags & SRQ_INTR) == 0) && 1314 !CPU_EMPTY(&tidlemsk)) 1315 forwarded = forward_wakeup(cpu); 1316 } 1317 1318 if (!forwarded) { 1319 if ((flags & SRQ_YIELDING) == 0 && maybe_preempt(td)) 1320 return; 1321 else 1322 maybe_resched(td); 1323 } 1324 } 1325 1326 if ((td->td_flags & TDF_NOLOAD) == 0) 1327 sched_load_add(); 1328 runq_add(ts->ts_runq, td, flags); 1329 if (cpu != NOCPU) 1330 runq_length[cpu]++; 1331 } 1332 #else /* SMP */ 1333 { 1334 struct td_sched *ts; 1335 1336 ts = td->td_sched; 1337 THREAD_LOCK_ASSERT(td, MA_OWNED); 1338 KASSERT((td->td_inhibitors == 0), 1339 ("sched_add: trying to run inhibited thread")); 1340 KASSERT((TD_CAN_RUN(td) || TD_IS_RUNNING(td)), 1341 ("sched_add: bad thread state")); 1342 KASSERT(td->td_flags & TDF_INMEM, 1343 ("sched_add: thread swapped out")); 1344 KTR_STATE2(KTR_SCHED, "thread", sched_tdname(td), "runq add", 1345 "prio:%d", td->td_priority, KTR_ATTR_LINKED, 1346 sched_tdname(curthread)); 1347 KTR_POINT1(KTR_SCHED, "thread", sched_tdname(curthread), "wokeup", 1348 KTR_ATTR_LINKED, sched_tdname(td)); 1349 SDT_PROBE4(sched, , , enqueue, td, td->td_proc, NULL, 1350 flags & SRQ_PREEMPTED); 1351 1352 /* 1353 * Now that the thread is moving to the run-queue, set the lock 1354 * to the scheduler's lock. 1355 */ 1356 if (td->td_lock != &sched_lock) { 1357 mtx_lock_spin(&sched_lock); 1358 thread_lock_set(td, &sched_lock); 1359 } 1360 TD_SET_RUNQ(td); 1361 CTR2(KTR_RUNQ, "sched_add: adding td_sched:%p (td:%p) to runq", ts, td); 1362 ts->ts_runq = &runq; 1363 1364 /* 1365 * If we are yielding (on the way out anyhow) or the thread 1366 * being saved is US, then don't try be smart about preemption 1367 * or kicking off another CPU as it won't help and may hinder. 1368 * In the YIEDLING case, we are about to run whoever is being 1369 * put in the queue anyhow, and in the OURSELF case, we are 1370 * puting ourself on the run queue which also only happens 1371 * when we are about to yield. 1372 */ 1373 if ((flags & SRQ_YIELDING) == 0) { 1374 if (maybe_preempt(td)) 1375 return; 1376 } 1377 if ((td->td_flags & TDF_NOLOAD) == 0) 1378 sched_load_add(); 1379 runq_add(ts->ts_runq, td, flags); 1380 maybe_resched(td); 1381 } 1382 #endif /* SMP */ 1383 1384 void 1385 sched_rem(struct thread *td) 1386 { 1387 struct td_sched *ts; 1388 1389 ts = td->td_sched; 1390 KASSERT(td->td_flags & TDF_INMEM, 1391 ("sched_rem: thread swapped out")); 1392 KASSERT(TD_ON_RUNQ(td), 1393 ("sched_rem: thread not on run queue")); 1394 mtx_assert(&sched_lock, MA_OWNED); 1395 KTR_STATE2(KTR_SCHED, "thread", sched_tdname(td), "runq rem", 1396 "prio:%d", td->td_priority, KTR_ATTR_LINKED, 1397 sched_tdname(curthread)); 1398 SDT_PROBE3(sched, , , dequeue, td, td->td_proc, NULL); 1399 1400 if ((td->td_flags & TDF_NOLOAD) == 0) 1401 sched_load_rem(); 1402 #ifdef SMP 1403 if (ts->ts_runq != &runq) 1404 runq_length[ts->ts_runq - runq_pcpu]--; 1405 #endif 1406 runq_remove(ts->ts_runq, td); 1407 TD_SET_CAN_RUN(td); 1408 } 1409 1410 /* 1411 * Select threads to run. Note that running threads still consume a 1412 * slot. 1413 */ 1414 struct thread * 1415 sched_choose(void) 1416 { 1417 struct thread *td; 1418 struct runq *rq; 1419 1420 mtx_assert(&sched_lock, MA_OWNED); 1421 #ifdef SMP 1422 struct thread *tdcpu; 1423 1424 rq = &runq; 1425 td = runq_choose_fuzz(&runq, runq_fuzz); 1426 tdcpu = runq_choose(&runq_pcpu[PCPU_GET(cpuid)]); 1427 1428 if (td == NULL || 1429 (tdcpu != NULL && 1430 tdcpu->td_priority < td->td_priority)) { 1431 CTR2(KTR_RUNQ, "choosing td %p from pcpu runq %d", tdcpu, 1432 PCPU_GET(cpuid)); 1433 td = tdcpu; 1434 rq = &runq_pcpu[PCPU_GET(cpuid)]; 1435 } else { 1436 CTR1(KTR_RUNQ, "choosing td_sched %p from main runq", td); 1437 } 1438 1439 #else 1440 rq = &runq; 1441 td = runq_choose(&runq); 1442 #endif 1443 1444 if (td) { 1445 #ifdef SMP 1446 if (td == tdcpu) 1447 runq_length[PCPU_GET(cpuid)]--; 1448 #endif 1449 runq_remove(rq, td); 1450 td->td_flags |= TDF_DIDRUN; 1451 1452 KASSERT(td->td_flags & TDF_INMEM, 1453 ("sched_choose: thread swapped out")); 1454 return (td); 1455 } 1456 return (PCPU_GET(idlethread)); 1457 } 1458 1459 void 1460 sched_preempt(struct thread *td) 1461 { 1462 1463 SDT_PROBE2(sched, , , surrender, td, td->td_proc); 1464 thread_lock(td); 1465 if (td->td_critnest > 1) 1466 td->td_owepreempt = 1; 1467 else 1468 mi_switch(SW_INVOL | SW_PREEMPT | SWT_PREEMPT, NULL); 1469 thread_unlock(td); 1470 } 1471 1472 void 1473 sched_userret(struct thread *td) 1474 { 1475 /* 1476 * XXX we cheat slightly on the locking here to avoid locking in 1477 * the usual case. Setting td_priority here is essentially an 1478 * incomplete workaround for not setting it properly elsewhere. 1479 * Now that some interrupt handlers are threads, not setting it 1480 * properly elsewhere can clobber it in the window between setting 1481 * it here and returning to user mode, so don't waste time setting 1482 * it perfectly here. 1483 */ 1484 KASSERT((td->td_flags & TDF_BORROWING) == 0, 1485 ("thread with borrowed priority returning to userland")); 1486 if (td->td_priority != td->td_user_pri) { 1487 thread_lock(td); 1488 td->td_priority = td->td_user_pri; 1489 td->td_base_pri = td->td_user_pri; 1490 thread_unlock(td); 1491 } 1492 } 1493 1494 void 1495 sched_bind(struct thread *td, int cpu) 1496 { 1497 struct td_sched *ts; 1498 1499 THREAD_LOCK_ASSERT(td, MA_OWNED|MA_NOTRECURSED); 1500 KASSERT(td == curthread, ("sched_bind: can only bind curthread")); 1501 1502 ts = td->td_sched; 1503 1504 td->td_flags |= TDF_BOUND; 1505 #ifdef SMP 1506 ts->ts_runq = &runq_pcpu[cpu]; 1507 if (PCPU_GET(cpuid) == cpu) 1508 return; 1509 1510 mi_switch(SW_VOL, NULL); 1511 #endif 1512 } 1513 1514 void 1515 sched_unbind(struct thread* td) 1516 { 1517 THREAD_LOCK_ASSERT(td, MA_OWNED); 1518 KASSERT(td == curthread, ("sched_unbind: can only bind curthread")); 1519 td->td_flags &= ~TDF_BOUND; 1520 } 1521 1522 int 1523 sched_is_bound(struct thread *td) 1524 { 1525 THREAD_LOCK_ASSERT(td, MA_OWNED); 1526 return (td->td_flags & TDF_BOUND); 1527 } 1528 1529 void 1530 sched_relinquish(struct thread *td) 1531 { 1532 thread_lock(td); 1533 mi_switch(SW_VOL | SWT_RELINQUISH, NULL); 1534 thread_unlock(td); 1535 } 1536 1537 int 1538 sched_load(void) 1539 { 1540 return (sched_tdcnt); 1541 } 1542 1543 int 1544 sched_sizeof_proc(void) 1545 { 1546 return (sizeof(struct proc)); 1547 } 1548 1549 int 1550 sched_sizeof_thread(void) 1551 { 1552 return (sizeof(struct thread) + sizeof(struct td_sched)); 1553 } 1554 1555 fixpt_t 1556 sched_pctcpu(struct thread *td) 1557 { 1558 struct td_sched *ts; 1559 1560 THREAD_LOCK_ASSERT(td, MA_OWNED); 1561 ts = td->td_sched; 1562 return (ts->ts_pctcpu); 1563 } 1564 1565 void 1566 sched_tick(int cnt) 1567 { 1568 } 1569 1570 /* 1571 * The actual idle process. 1572 */ 1573 void 1574 sched_idletd(void *dummy) 1575 { 1576 struct pcpuidlestat *stat; 1577 1578 stat = DPCPU_PTR(idlestat); 1579 for (;;) { 1580 mtx_assert(&Giant, MA_NOTOWNED); 1581 1582 while (sched_runnable() == 0) { 1583 cpu_idle(stat->idlecalls + stat->oldidlecalls > 64); 1584 stat->idlecalls++; 1585 } 1586 1587 mtx_lock_spin(&sched_lock); 1588 mi_switch(SW_VOL | SWT_IDLE, NULL); 1589 mtx_unlock_spin(&sched_lock); 1590 } 1591 } 1592 1593 /* 1594 * A CPU is entering for the first time or a thread is exiting. 1595 */ 1596 void 1597 sched_throw(struct thread *td) 1598 { 1599 /* 1600 * Correct spinlock nesting. The idle thread context that we are 1601 * borrowing was created so that it would start out with a single 1602 * spin lock (sched_lock) held in fork_trampoline(). Since we've 1603 * explicitly acquired locks in this function, the nesting count 1604 * is now 2 rather than 1. Since we are nested, calling 1605 * spinlock_exit() will simply adjust the counts without allowing 1606 * spin lock using code to interrupt us. 1607 */ 1608 if (td == NULL) { 1609 mtx_lock_spin(&sched_lock); 1610 spinlock_exit(); 1611 PCPU_SET(switchtime, cpu_ticks()); 1612 PCPU_SET(switchticks, ticks); 1613 } else { 1614 lock_profile_release_lock(&sched_lock.lock_object); 1615 MPASS(td->td_lock == &sched_lock); 1616 } 1617 mtx_assert(&sched_lock, MA_OWNED); 1618 KASSERT(curthread->td_md.md_spinlock_count == 1, ("invalid count")); 1619 cpu_throw(td, choosethread()); /* doesn't return */ 1620 } 1621 1622 void 1623 sched_fork_exit(struct thread *td) 1624 { 1625 1626 /* 1627 * Finish setting up thread glue so that it begins execution in a 1628 * non-nested critical section with sched_lock held but not recursed. 1629 */ 1630 td->td_oncpu = PCPU_GET(cpuid); 1631 sched_lock.mtx_lock = (uintptr_t)td; 1632 lock_profile_obtain_lock_success(&sched_lock.lock_object, 1633 0, 0, __FILE__, __LINE__); 1634 THREAD_LOCK_ASSERT(td, MA_OWNED | MA_NOTRECURSED); 1635 } 1636 1637 char * 1638 sched_tdname(struct thread *td) 1639 { 1640 #ifdef KTR 1641 struct td_sched *ts; 1642 1643 ts = td->td_sched; 1644 if (ts->ts_name[0] == '\0') 1645 snprintf(ts->ts_name, sizeof(ts->ts_name), 1646 "%s tid %d", td->td_name, td->td_tid); 1647 return (ts->ts_name); 1648 #else 1649 return (td->td_name); 1650 #endif 1651 } 1652 1653 #ifdef KTR 1654 void 1655 sched_clear_tdname(struct thread *td) 1656 { 1657 struct td_sched *ts; 1658 1659 ts = td->td_sched; 1660 ts->ts_name[0] = '\0'; 1661 } 1662 #endif 1663 1664 void 1665 sched_affinity(struct thread *td) 1666 { 1667 #ifdef SMP 1668 struct td_sched *ts; 1669 int cpu; 1670 1671 THREAD_LOCK_ASSERT(td, MA_OWNED); 1672 1673 /* 1674 * Set the TSF_AFFINITY flag if there is at least one CPU this 1675 * thread can't run on. 1676 */ 1677 ts = td->td_sched; 1678 ts->ts_flags &= ~TSF_AFFINITY; 1679 CPU_FOREACH(cpu) { 1680 if (!THREAD_CAN_SCHED(td, cpu)) { 1681 ts->ts_flags |= TSF_AFFINITY; 1682 break; 1683 } 1684 } 1685 1686 /* 1687 * If this thread can run on all CPUs, nothing else to do. 1688 */ 1689 if (!(ts->ts_flags & TSF_AFFINITY)) 1690 return; 1691 1692 /* Pinned threads and bound threads should be left alone. */ 1693 if (td->td_pinned != 0 || td->td_flags & TDF_BOUND) 1694 return; 1695 1696 switch (td->td_state) { 1697 case TDS_RUNQ: 1698 /* 1699 * If we are on a per-CPU runqueue that is in the set, 1700 * then nothing needs to be done. 1701 */ 1702 if (ts->ts_runq != &runq && 1703 THREAD_CAN_SCHED(td, ts->ts_runq - runq_pcpu)) 1704 return; 1705 1706 /* Put this thread on a valid per-CPU runqueue. */ 1707 sched_rem(td); 1708 sched_add(td, SRQ_BORING); 1709 break; 1710 case TDS_RUNNING: 1711 /* 1712 * See if our current CPU is in the set. If not, force a 1713 * context switch. 1714 */ 1715 if (THREAD_CAN_SCHED(td, td->td_oncpu)) 1716 return; 1717 1718 td->td_flags |= TDF_NEEDRESCHED; 1719 if (td != curthread) 1720 ipi_cpu(cpu, IPI_AST); 1721 break; 1722 default: 1723 break; 1724 } 1725 #endif 1726 }
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