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