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