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 /* 86 * The schedulable entity that runs a context. 87 * This is an extension to the thread structure and is tailored to 88 * the requirements of this scheduler 89 */ 90 struct td_sched { 91 fixpt_t ts_pctcpu; /* (j) %cpu during p_swtime. */ 92 int ts_cpticks; /* (j) Ticks of cpu time. */ 93 int ts_slptime; /* (j) Seconds !RUNNING. */ 94 int ts_flags; 95 struct runq *ts_runq; /* runq the thread is currently on */ 96 }; 97 98 /* flags kept in td_flags */ 99 #define TDF_DIDRUN TDF_SCHED0 /* thread actually ran. */ 100 #define TDF_BOUND TDF_SCHED1 /* Bound to one CPU. */ 101 102 /* flags kept in ts_flags */ 103 #define TSF_AFFINITY 0x0001 /* Has a non-"full" CPU set. */ 104 105 #define SKE_RUNQ_PCPU(ts) \ 106 ((ts)->ts_runq != 0 && (ts)->ts_runq != &runq) 107 108 #define THREAD_CAN_SCHED(td, cpu) \ 109 CPU_ISSET((cpu), &(td)->td_cpuset->cs_mask) 110 111 static struct td_sched td_sched0; 112 struct mtx sched_lock; 113 114 static int sched_tdcnt; /* Total runnable threads in the system. */ 115 static int sched_quantum; /* Roundrobin scheduling quantum in ticks. */ 116 #define SCHED_QUANTUM (hz / 10) /* Default sched quantum */ 117 118 static void setup_runqs(void); 119 static void schedcpu(void); 120 static void schedcpu_thread(void); 121 static void sched_priority(struct thread *td, u_char prio); 122 static void sched_setup(void *dummy); 123 static void maybe_resched(struct thread *td); 124 static void updatepri(struct thread *td); 125 static void resetpriority(struct thread *td); 126 static void resetpriority_thread(struct thread *td); 127 #ifdef SMP 128 static int sched_pickcpu(struct thread *td); 129 static int forward_wakeup(int cpunum); 130 static void kick_other_cpu(int pri, int cpuid); 131 #endif 132 133 static struct kproc_desc sched_kp = { 134 "schedcpu", 135 schedcpu_thread, 136 NULL 137 }; 138 SYSINIT(schedcpu, SI_SUB_RUN_SCHEDULER, SI_ORDER_FIRST, kproc_start, 139 &sched_kp); 140 SYSINIT(sched_setup, SI_SUB_RUN_QUEUE, SI_ORDER_FIRST, sched_setup, NULL); 141 142 /* 143 * Global run queue. 144 */ 145 static struct runq runq; 146 147 #ifdef SMP 148 /* 149 * Per-CPU run queues 150 */ 151 static struct runq runq_pcpu[MAXCPU]; 152 long runq_length[MAXCPU]; 153 #endif 154 155 static void 156 setup_runqs(void) 157 { 158 #ifdef SMP 159 int i; 160 161 for (i = 0; i < MAXCPU; ++i) 162 runq_init(&runq_pcpu[i]); 163 #endif 164 165 runq_init(&runq); 166 } 167 168 static int 169 sysctl_kern_quantum(SYSCTL_HANDLER_ARGS) 170 { 171 int error, new_val; 172 173 new_val = sched_quantum * tick; 174 error = sysctl_handle_int(oidp, &new_val, 0, req); 175 if (error != 0 || req->newptr == NULL) 176 return (error); 177 if (new_val < tick) 178 return (EINVAL); 179 sched_quantum = new_val / tick; 180 hogticks = 2 * sched_quantum; 181 return (0); 182 } 183 184 SYSCTL_NODE(_kern, OID_AUTO, sched, CTLFLAG_RD, 0, "Scheduler"); 185 186 SYSCTL_STRING(_kern_sched, OID_AUTO, name, CTLFLAG_RD, "4BSD", 0, 187 "Scheduler name"); 188 189 SYSCTL_PROC(_kern_sched, OID_AUTO, quantum, CTLTYPE_INT | CTLFLAG_RW, 190 0, sizeof sched_quantum, sysctl_kern_quantum, "I", 191 "Roundrobin scheduling quantum in microseconds"); 192 193 #ifdef SMP 194 /* Enable forwarding of wakeups to all other cpus */ 195 SYSCTL_NODE(_kern_sched, OID_AUTO, ipiwakeup, CTLFLAG_RD, NULL, "Kernel SMP"); 196 197 static int runq_fuzz = 1; 198 SYSCTL_INT(_kern_sched, OID_AUTO, runq_fuzz, CTLFLAG_RW, &runq_fuzz, 0, ""); 199 200 static int forward_wakeup_enabled = 1; 201 SYSCTL_INT(_kern_sched_ipiwakeup, OID_AUTO, enabled, CTLFLAG_RW, 202 &forward_wakeup_enabled, 0, 203 "Forwarding of wakeup to idle CPUs"); 204 205 static int forward_wakeups_requested = 0; 206 SYSCTL_INT(_kern_sched_ipiwakeup, OID_AUTO, requested, CTLFLAG_RD, 207 &forward_wakeups_requested, 0, 208 "Requests for Forwarding of wakeup to idle CPUs"); 209 210 static int forward_wakeups_delivered = 0; 211 SYSCTL_INT(_kern_sched_ipiwakeup, OID_AUTO, delivered, CTLFLAG_RD, 212 &forward_wakeups_delivered, 0, 213 "Completed Forwarding of wakeup to idle CPUs"); 214 215 static int forward_wakeup_use_mask = 1; 216 SYSCTL_INT(_kern_sched_ipiwakeup, OID_AUTO, usemask, CTLFLAG_RW, 217 &forward_wakeup_use_mask, 0, 218 "Use the mask of idle cpus"); 219 220 static int forward_wakeup_use_loop = 0; 221 SYSCTL_INT(_kern_sched_ipiwakeup, OID_AUTO, useloop, CTLFLAG_RW, 222 &forward_wakeup_use_loop, 0, 223 "Use a loop to find idle cpus"); 224 225 static int forward_wakeup_use_single = 0; 226 SYSCTL_INT(_kern_sched_ipiwakeup, OID_AUTO, onecpu, CTLFLAG_RW, 227 &forward_wakeup_use_single, 0, 228 "Only signal one idle cpu"); 229 230 static int forward_wakeup_use_htt = 0; 231 SYSCTL_INT(_kern_sched_ipiwakeup, OID_AUTO, htt2, CTLFLAG_RW, 232 &forward_wakeup_use_htt, 0, 233 "account for htt"); 234 235 #endif 236 #if 0 237 static int sched_followon = 0; 238 SYSCTL_INT(_kern_sched, OID_AUTO, followon, CTLFLAG_RW, 239 &sched_followon, 0, 240 "allow threads to share a quantum"); 241 #endif 242 243 static __inline void 244 sched_load_add(void) 245 { 246 sched_tdcnt++; 247 CTR1(KTR_SCHED, "global load: %d", sched_tdcnt); 248 } 249 250 static __inline void 251 sched_load_rem(void) 252 { 253 sched_tdcnt--; 254 CTR1(KTR_SCHED, "global load: %d", sched_tdcnt); 255 } 256 /* 257 * Arrange to reschedule if necessary, taking the priorities and 258 * schedulers into account. 259 */ 260 static void 261 maybe_resched(struct thread *td) 262 { 263 264 THREAD_LOCK_ASSERT(td, MA_OWNED); 265 if (td->td_priority < curthread->td_priority) 266 curthread->td_flags |= TDF_NEEDRESCHED; 267 } 268 269 /* 270 * This function is called when a thread is about to be put on run queue 271 * because it has been made runnable or its priority has been adjusted. It 272 * determines if the new thread should be immediately preempted to. If so, 273 * it switches to it and eventually returns true. If not, it returns false 274 * so that the caller may place the thread on an appropriate run queue. 275 */ 276 int 277 maybe_preempt(struct thread *td) 278 { 279 #ifdef PREEMPTION 280 struct thread *ctd; 281 int cpri, pri; 282 283 /* 284 * The new thread should not preempt the current thread if any of the 285 * following conditions are true: 286 * 287 * - The kernel is in the throes of crashing (panicstr). 288 * - The current thread has a higher (numerically lower) or 289 * equivalent priority. Note that this prevents curthread from 290 * trying to preempt to itself. 291 * - It is too early in the boot for context switches (cold is set). 292 * - The current thread has an inhibitor set or is in the process of 293 * exiting. In this case, the current thread is about to switch 294 * out anyways, so there's no point in preempting. If we did, 295 * the current thread would not be properly resumed as well, so 296 * just avoid that whole landmine. 297 * - If the new thread's priority is not a realtime priority and 298 * the current thread's priority is not an idle priority and 299 * FULL_PREEMPTION is disabled. 300 * 301 * If all of these conditions are false, but the current thread is in 302 * a nested critical section, then we have to defer the preemption 303 * until we exit the critical section. Otherwise, switch immediately 304 * to the new thread. 305 */ 306 ctd = curthread; 307 THREAD_LOCK_ASSERT(td, MA_OWNED); 308 KASSERT((td->td_inhibitors == 0), 309 ("maybe_preempt: trying to run inhibited thread")); 310 pri = td->td_priority; 311 cpri = ctd->td_priority; 312 if (panicstr != NULL || pri >= cpri || cold /* || dumping */ || 313 TD_IS_INHIBITED(ctd)) 314 return (0); 315 #ifndef FULL_PREEMPTION 316 if (pri > PRI_MAX_ITHD && cpri < PRI_MIN_IDLE) 317 return (0); 318 #endif 319 320 if (ctd->td_critnest > 1) { 321 CTR1(KTR_PROC, "maybe_preempt: in critical section %d", 322 ctd->td_critnest); 323 ctd->td_owepreempt = 1; 324 return (0); 325 } 326 /* 327 * Thread is runnable but not yet put on system run queue. 328 */ 329 MPASS(ctd->td_lock == td->td_lock); 330 MPASS(TD_ON_RUNQ(td)); 331 TD_SET_RUNNING(td); 332 CTR3(KTR_PROC, "preempting to thread %p (pid %d, %s)\n", td, 333 td->td_proc->p_pid, td->td_name); 334 mi_switch(SW_INVOL | SW_PREEMPT | SWT_PREEMPT, td); 335 /* 336 * td's lock pointer may have changed. We have to return with it 337 * locked. 338 */ 339 spinlock_enter(); 340 thread_unlock(ctd); 341 thread_lock(td); 342 spinlock_exit(); 343 return (1); 344 #else 345 return (0); 346 #endif 347 } 348 349 /* 350 * Constants for digital decay and forget: 351 * 90% of (td_estcpu) usage in 5 * loadav time 352 * 95% of (ts_pctcpu) usage in 60 seconds (load insensitive) 353 * Note that, as ps(1) mentions, this can let percentages 354 * total over 100% (I've seen 137.9% for 3 processes). 355 * 356 * Note that schedclock() updates td_estcpu and p_cpticks asynchronously. 357 * 358 * We wish to decay away 90% of td_estcpu in (5 * loadavg) seconds. 359 * That is, the system wants to compute a value of decay such 360 * that the following for loop: 361 * for (i = 0; i < (5 * loadavg); i++) 362 * td_estcpu *= decay; 363 * will compute 364 * td_estcpu *= 0.1; 365 * for all values of loadavg: 366 * 367 * Mathematically this loop can be expressed by saying: 368 * decay ** (5 * loadavg) ~= .1 369 * 370 * The system computes decay as: 371 * decay = (2 * loadavg) / (2 * loadavg + 1) 372 * 373 * We wish to prove that the system's computation of decay 374 * will always fulfill the equation: 375 * decay ** (5 * loadavg) ~= .1 376 * 377 * If we compute b as: 378 * b = 2 * loadavg 379 * then 380 * decay = b / (b + 1) 381 * 382 * We now need to prove two things: 383 * 1) Given factor ** (5 * loadavg) ~= .1, prove factor == b/(b+1) 384 * 2) Given b/(b+1) ** power ~= .1, prove power == (5 * loadavg) 385 * 386 * Facts: 387 * For x close to zero, exp(x) =~ 1 + x, since 388 * exp(x) = 0! + x**1/1! + x**2/2! + ... . 389 * therefore exp(-1/b) =~ 1 - (1/b) = (b-1)/b. 390 * For x close to zero, ln(1+x) =~ x, since 391 * ln(1+x) = x - x**2/2 + x**3/3 - ... -1 < x < 1 392 * therefore ln(b/(b+1)) = ln(1 - 1/(b+1)) =~ -1/(b+1). 393 * ln(.1) =~ -2.30 394 * 395 * Proof of (1): 396 * Solve (factor)**(power) =~ .1 given power (5*loadav): 397 * solving for factor, 398 * ln(factor) =~ (-2.30/5*loadav), or 399 * factor =~ exp(-1/((5/2.30)*loadav)) =~ exp(-1/(2*loadav)) = 400 * exp(-1/b) =~ (b-1)/b =~ b/(b+1). QED 401 * 402 * Proof of (2): 403 * Solve (factor)**(power) =~ .1 given factor == (b/(b+1)): 404 * solving for power, 405 * power*ln(b/(b+1)) =~ -2.30, or 406 * power =~ 2.3 * (b + 1) = 4.6*loadav + 2.3 =~ 5*loadav. QED 407 * 408 * Actual power values for the implemented algorithm are as follows: 409 * loadav: 1 2 3 4 410 * power: 5.68 10.32 14.94 19.55 411 */ 412 413 /* calculations for digital decay to forget 90% of usage in 5*loadav sec */ 414 #define loadfactor(loadav) (2 * (loadav)) 415 #define decay_cpu(loadfac, cpu) (((loadfac) * (cpu)) / ((loadfac) + FSCALE)) 416 417 /* decay 95% of `ts_pctcpu' in 60 seconds; see CCPU_SHIFT before changing */ 418 static fixpt_t ccpu = 0.95122942450071400909 * FSCALE; /* exp(-1/20) */ 419 SYSCTL_INT(_kern, OID_AUTO, ccpu, CTLFLAG_RD, &ccpu, 0, ""); 420 421 /* 422 * If `ccpu' is not equal to `exp(-1/20)' and you still want to use the 423 * faster/more-accurate formula, you'll have to estimate CCPU_SHIFT below 424 * and possibly adjust FSHIFT in "param.h" so that (FSHIFT >= CCPU_SHIFT). 425 * 426 * To estimate CCPU_SHIFT for exp(-1/20), the following formula was used: 427 * 1 - exp(-1/20) ~= 0.0487 ~= 0.0488 == 1 (fixed pt, *11* bits). 428 * 429 * If you don't want to bother with the faster/more-accurate formula, you 430 * can set CCPU_SHIFT to (FSHIFT + 1) which will use a slower/less-accurate 431 * (more general) method of calculating the %age of CPU used by a process. 432 */ 433 #define CCPU_SHIFT 11 434 435 /* 436 * Recompute process priorities, every hz ticks. 437 * MP-safe, called without the Giant mutex. 438 */ 439 /* ARGSUSED */ 440 static void 441 schedcpu(void) 442 { 443 register fixpt_t loadfac = loadfactor(averunnable.ldavg[0]); 444 struct thread *td; 445 struct proc *p; 446 struct td_sched *ts; 447 int awake, realstathz; 448 449 realstathz = stathz ? stathz : hz; 450 sx_slock(&allproc_lock); 451 FOREACH_PROC_IN_SYSTEM(p) { 452 PROC_LOCK(p); 453 FOREACH_THREAD_IN_PROC(p, td) { 454 awake = 0; 455 thread_lock(td); 456 ts = td->td_sched; 457 /* 458 * Increment sleep time (if sleeping). We 459 * ignore overflow, as above. 460 */ 461 /* 462 * The td_sched slptimes are not touched in wakeup 463 * because the thread may not HAVE everything in 464 * memory? XXX I think this is out of date. 465 */ 466 if (TD_ON_RUNQ(td)) { 467 awake = 1; 468 td->td_flags &= ~TDF_DIDRUN; 469 } else if (TD_IS_RUNNING(td)) { 470 awake = 1; 471 /* Do not clear TDF_DIDRUN */ 472 } else if (td->td_flags & TDF_DIDRUN) { 473 awake = 1; 474 td->td_flags &= ~TDF_DIDRUN; 475 } 476 477 /* 478 * ts_pctcpu is only for ps and ttyinfo(). 479 */ 480 ts->ts_pctcpu = (ts->ts_pctcpu * ccpu) >> FSHIFT; 481 /* 482 * If the td_sched has been idle the entire second, 483 * stop recalculating its priority until 484 * it wakes up. 485 */ 486 if (ts->ts_cpticks != 0) { 487 #if (FSHIFT >= CCPU_SHIFT) 488 ts->ts_pctcpu += (realstathz == 100) 489 ? ((fixpt_t) ts->ts_cpticks) << 490 (FSHIFT - CCPU_SHIFT) : 491 100 * (((fixpt_t) ts->ts_cpticks) 492 << (FSHIFT - CCPU_SHIFT)) / realstathz; 493 #else 494 ts->ts_pctcpu += ((FSCALE - ccpu) * 495 (ts->ts_cpticks * 496 FSCALE / realstathz)) >> FSHIFT; 497 #endif 498 ts->ts_cpticks = 0; 499 } 500 /* 501 * If there are ANY running threads in this process, 502 * then don't count it as sleeping. 503 * XXX: this is broken. 504 */ 505 if (awake) { 506 if (ts->ts_slptime > 1) { 507 /* 508 * In an ideal world, this should not 509 * happen, because whoever woke us 510 * up from the long sleep should have 511 * unwound the slptime and reset our 512 * priority before we run at the stale 513 * priority. Should KASSERT at some 514 * point when all the cases are fixed. 515 */ 516 updatepri(td); 517 } 518 ts->ts_slptime = 0; 519 } else 520 ts->ts_slptime++; 521 if (ts->ts_slptime > 1) { 522 thread_unlock(td); 523 continue; 524 } 525 td->td_estcpu = decay_cpu(loadfac, td->td_estcpu); 526 resetpriority(td); 527 resetpriority_thread(td); 528 thread_unlock(td); 529 } 530 PROC_UNLOCK(p); 531 } 532 sx_sunlock(&allproc_lock); 533 } 534 535 /* 536 * Main loop for a kthread that executes schedcpu once a second. 537 */ 538 static void 539 schedcpu_thread(void) 540 { 541 542 for (;;) { 543 schedcpu(); 544 pause("-", hz); 545 } 546 } 547 548 /* 549 * Recalculate the priority of a process after it has slept for a while. 550 * For all load averages >= 1 and max td_estcpu of 255, sleeping for at 551 * least six times the loadfactor will decay td_estcpu to zero. 552 */ 553 static void 554 updatepri(struct thread *td) 555 { 556 struct td_sched *ts; 557 fixpt_t loadfac; 558 unsigned int newcpu; 559 560 ts = td->td_sched; 561 loadfac = loadfactor(averunnable.ldavg[0]); 562 if (ts->ts_slptime > 5 * loadfac) 563 td->td_estcpu = 0; 564 else { 565 newcpu = td->td_estcpu; 566 ts->ts_slptime--; /* was incremented in schedcpu() */ 567 while (newcpu && --ts->ts_slptime) 568 newcpu = decay_cpu(loadfac, newcpu); 569 td->td_estcpu = newcpu; 570 } 571 } 572 573 /* 574 * Compute the priority of a process when running in user mode. 575 * Arrange to reschedule if the resulting priority is better 576 * than that of the current process. 577 */ 578 static void 579 resetpriority(struct thread *td) 580 { 581 register unsigned int newpriority; 582 583 if (td->td_pri_class == PRI_TIMESHARE) { 584 newpriority = PUSER + td->td_estcpu / INVERSE_ESTCPU_WEIGHT + 585 NICE_WEIGHT * (td->td_proc->p_nice - PRIO_MIN); 586 newpriority = min(max(newpriority, PRI_MIN_TIMESHARE), 587 PRI_MAX_TIMESHARE); 588 sched_user_prio(td, newpriority); 589 } 590 } 591 592 /* 593 * Update the thread's priority when the associated process's user 594 * priority changes. 595 */ 596 static void 597 resetpriority_thread(struct thread *td) 598 { 599 600 /* Only change threads with a time sharing user priority. */ 601 if (td->td_priority < PRI_MIN_TIMESHARE || 602 td->td_priority > PRI_MAX_TIMESHARE) 603 return; 604 605 /* XXX the whole needresched thing is broken, but not silly. */ 606 maybe_resched(td); 607 608 sched_prio(td, td->td_user_pri); 609 } 610 611 /* ARGSUSED */ 612 static void 613 sched_setup(void *dummy) 614 { 615 setup_runqs(); 616 617 if (sched_quantum == 0) 618 sched_quantum = SCHED_QUANTUM; 619 hogticks = 2 * sched_quantum; 620 621 /* Account for thread0. */ 622 sched_load_add(); 623 } 624 625 /* External interfaces start here */ 626 627 /* 628 * Very early in the boot some setup of scheduler-specific 629 * parts of proc0 and of some scheduler resources needs to be done. 630 * Called from: 631 * proc0_init() 632 */ 633 void 634 schedinit(void) 635 { 636 /* 637 * Set up the scheduler specific parts of proc0. 638 */ 639 proc0.p_sched = NULL; /* XXX */ 640 thread0.td_sched = &td_sched0; 641 thread0.td_lock = &sched_lock; 642 mtx_init(&sched_lock, "sched lock", NULL, MTX_SPIN | MTX_RECURSE); 643 } 644 645 int 646 sched_runnable(void) 647 { 648 #ifdef SMP 649 return runq_check(&runq) + runq_check(&runq_pcpu[PCPU_GET(cpuid)]); 650 #else 651 return runq_check(&runq); 652 #endif 653 } 654 655 int 656 sched_rr_interval(void) 657 { 658 if (sched_quantum == 0) 659 sched_quantum = SCHED_QUANTUM; 660 return (sched_quantum); 661 } 662 663 /* 664 * We adjust the priority of the current process. The priority of 665 * a process gets worse as it accumulates CPU time. The cpu usage 666 * estimator (td_estcpu) is increased here. resetpriority() will 667 * compute a different priority each time td_estcpu increases by 668 * INVERSE_ESTCPU_WEIGHT 669 * (until MAXPRI is reached). The cpu usage estimator ramps up 670 * quite quickly when the process is running (linearly), and decays 671 * away exponentially, at a rate which is proportionally slower when 672 * the system is busy. The basic principle is that the system will 673 * 90% forget that the process used a lot of CPU time in 5 * loadav 674 * seconds. This causes the system to favor processes which haven't 675 * run much recently, and to round-robin among other processes. 676 */ 677 void 678 sched_clock(struct thread *td) 679 { 680 struct td_sched *ts; 681 682 THREAD_LOCK_ASSERT(td, MA_OWNED); 683 ts = td->td_sched; 684 685 ts->ts_cpticks++; 686 td->td_estcpu = ESTCPULIM(td->td_estcpu + 1); 687 if ((td->td_estcpu % INVERSE_ESTCPU_WEIGHT) == 0) { 688 resetpriority(td); 689 resetpriority_thread(td); 690 } 691 692 /* 693 * Force a context switch if the current thread has used up a full 694 * quantum (default quantum is 100ms). 695 */ 696 if (!TD_IS_IDLETHREAD(td) && 697 ticks - PCPU_GET(switchticks) >= sched_quantum) 698 td->td_flags |= TDF_NEEDRESCHED; 699 } 700 701 /* 702 * Charge child's scheduling CPU usage to parent. 703 */ 704 void 705 sched_exit(struct proc *p, struct thread *td) 706 { 707 708 CTR3(KTR_SCHED, "sched_exit: %p(%s) prio %d", 709 td, td->td_name, td->td_priority); 710 PROC_LOCK_ASSERT(p, MA_OWNED); 711 sched_exit_thread(FIRST_THREAD_IN_PROC(p), td); 712 } 713 714 void 715 sched_exit_thread(struct thread *td, struct thread *child) 716 { 717 718 CTR3(KTR_SCHED, "sched_exit_thread: %p(%s) prio %d", 719 child, child->td_name, child->td_priority); 720 thread_lock(td); 721 td->td_estcpu = ESTCPULIM(td->td_estcpu + child->td_estcpu); 722 thread_unlock(td); 723 mtx_lock_spin(&sched_lock); 724 if ((child->td_proc->p_flag & P_NOLOAD) == 0) 725 sched_load_rem(); 726 mtx_unlock_spin(&sched_lock); 727 } 728 729 void 730 sched_fork(struct thread *td, struct thread *childtd) 731 { 732 sched_fork_thread(td, childtd); 733 } 734 735 void 736 sched_fork_thread(struct thread *td, struct thread *childtd) 737 { 738 struct td_sched *ts; 739 740 childtd->td_estcpu = td->td_estcpu; 741 childtd->td_lock = &sched_lock; 742 childtd->td_cpuset = cpuset_ref(td->td_cpuset); 743 ts = childtd->td_sched; 744 bzero(ts, sizeof(*ts)); 745 ts->ts_flags |= (td->td_sched->ts_flags & TSF_AFFINITY); 746 } 747 748 void 749 sched_nice(struct proc *p, int nice) 750 { 751 struct thread *td; 752 753 PROC_LOCK_ASSERT(p, MA_OWNED); 754 p->p_nice = nice; 755 FOREACH_THREAD_IN_PROC(p, td) { 756 thread_lock(td); 757 resetpriority(td); 758 resetpriority_thread(td); 759 thread_unlock(td); 760 } 761 } 762 763 void 764 sched_class(struct thread *td, int class) 765 { 766 THREAD_LOCK_ASSERT(td, MA_OWNED); 767 td->td_pri_class = class; 768 } 769 770 /* 771 * Adjust the priority of a thread. 772 */ 773 static void 774 sched_priority(struct thread *td, u_char prio) 775 { 776 CTR6(KTR_SCHED, "sched_prio: %p(%s) prio %d newprio %d by %p(%s)", 777 td, td->td_name, td->td_priority, prio, curthread, 778 curthread->td_name); 779 780 THREAD_LOCK_ASSERT(td, MA_OWNED); 781 if (td->td_priority == prio) 782 return; 783 td->td_priority = prio; 784 if (TD_ON_RUNQ(td) && td->td_rqindex != (prio / RQ_PPQ)) { 785 sched_rem(td); 786 sched_add(td, SRQ_BORING); 787 } 788 } 789 790 /* 791 * Update a thread's priority when it is lent another thread's 792 * priority. 793 */ 794 void 795 sched_lend_prio(struct thread *td, u_char prio) 796 { 797 798 td->td_flags |= TDF_BORROWING; 799 sched_priority(td, prio); 800 } 801 802 /* 803 * Restore a thread's priority when priority propagation is 804 * over. The prio argument is the minimum priority the thread 805 * needs to have to satisfy other possible priority lending 806 * requests. If the thread's regulary priority is less 807 * important than prio the thread will keep a priority boost 808 * of prio. 809 */ 810 void 811 sched_unlend_prio(struct thread *td, u_char prio) 812 { 813 u_char base_pri; 814 815 if (td->td_base_pri >= PRI_MIN_TIMESHARE && 816 td->td_base_pri <= PRI_MAX_TIMESHARE) 817 base_pri = td->td_user_pri; 818 else 819 base_pri = td->td_base_pri; 820 if (prio >= base_pri) { 821 td->td_flags &= ~TDF_BORROWING; 822 sched_prio(td, base_pri); 823 } else 824 sched_lend_prio(td, prio); 825 } 826 827 void 828 sched_prio(struct thread *td, u_char prio) 829 { 830 u_char oldprio; 831 832 /* First, update the base priority. */ 833 td->td_base_pri = prio; 834 835 /* 836 * If the thread is borrowing another thread's priority, don't ever 837 * lower the priority. 838 */ 839 if (td->td_flags & TDF_BORROWING && td->td_priority < prio) 840 return; 841 842 /* Change the real priority. */ 843 oldprio = td->td_priority; 844 sched_priority(td, prio); 845 846 /* 847 * If the thread is on a turnstile, then let the turnstile update 848 * its state. 849 */ 850 if (TD_ON_LOCK(td) && oldprio != prio) 851 turnstile_adjust(td, oldprio); 852 } 853 854 void 855 sched_user_prio(struct thread *td, u_char prio) 856 { 857 u_char oldprio; 858 859 THREAD_LOCK_ASSERT(td, MA_OWNED); 860 td->td_base_user_pri = prio; 861 if (td->td_flags & TDF_UBORROWING && td->td_user_pri <= prio) 862 return; 863 oldprio = td->td_user_pri; 864 td->td_user_pri = prio; 865 } 866 867 void 868 sched_lend_user_prio(struct thread *td, u_char prio) 869 { 870 u_char oldprio; 871 872 THREAD_LOCK_ASSERT(td, MA_OWNED); 873 td->td_flags |= TDF_UBORROWING; 874 oldprio = td->td_user_pri; 875 td->td_user_pri = prio; 876 } 877 878 void 879 sched_unlend_user_prio(struct thread *td, u_char prio) 880 { 881 u_char base_pri; 882 883 THREAD_LOCK_ASSERT(td, MA_OWNED); 884 base_pri = td->td_base_user_pri; 885 if (prio >= base_pri) { 886 td->td_flags &= ~TDF_UBORROWING; 887 sched_user_prio(td, base_pri); 888 } else { 889 sched_lend_user_prio(td, prio); 890 } 891 } 892 893 void 894 sched_sleep(struct thread *td, int pri) 895 { 896 897 THREAD_LOCK_ASSERT(td, MA_OWNED); 898 td->td_slptick = ticks; 899 td->td_sched->ts_slptime = 0; 900 if (pri) 901 sched_prio(td, pri); 902 if (TD_IS_SUSPENDED(td) || pri <= PSOCK) 903 td->td_flags |= TDF_CANSWAP; 904 } 905 906 void 907 sched_switch(struct thread *td, struct thread *newtd, int flags) 908 { 909 struct td_sched *ts; 910 struct proc *p; 911 912 ts = td->td_sched; 913 p = td->td_proc; 914 915 THREAD_LOCK_ASSERT(td, MA_OWNED); 916 917 /* 918 * Switch to the sched lock to fix things up and pick 919 * a new thread. 920 */ 921 if (td->td_lock != &sched_lock) { 922 mtx_lock_spin(&sched_lock); 923 thread_unlock(td); 924 } 925 926 if ((p->p_flag & P_NOLOAD) == 0) 927 sched_load_rem(); 928 929 if (newtd) 930 newtd->td_flags |= (td->td_flags & TDF_NEEDRESCHED); 931 932 td->td_lastcpu = td->td_oncpu; 933 td->td_flags &= ~TDF_NEEDRESCHED; 934 td->td_owepreempt = 0; 935 td->td_oncpu = NOCPU; 936 937 /* 938 * At the last moment, if this thread is still marked RUNNING, 939 * then put it back on the run queue as it has not been suspended 940 * or stopped or any thing else similar. We never put the idle 941 * threads on the run queue, however. 942 */ 943 if (td->td_flags & TDF_IDLETD) { 944 TD_SET_CAN_RUN(td); 945 #ifdef SMP 946 idle_cpus_mask &= ~PCPU_GET(cpumask); 947 #endif 948 } else { 949 if (TD_IS_RUNNING(td)) { 950 /* Put us back on the run queue. */ 951 sched_add(td, (flags & SW_PREEMPT) ? 952 SRQ_OURSELF|SRQ_YIELDING|SRQ_PREEMPTED : 953 SRQ_OURSELF|SRQ_YIELDING); 954 } 955 } 956 if (newtd) { 957 /* 958 * The thread we are about to run needs to be counted 959 * as if it had been added to the run queue and selected. 960 * It came from: 961 * * A preemption 962 * * An upcall 963 * * A followon 964 */ 965 KASSERT((newtd->td_inhibitors == 0), 966 ("trying to run inhibited thread")); 967 newtd->td_flags |= TDF_DIDRUN; 968 TD_SET_RUNNING(newtd); 969 if ((newtd->td_proc->p_flag & P_NOLOAD) == 0) 970 sched_load_add(); 971 } else { 972 newtd = choosethread(); 973 } 974 MPASS(newtd->td_lock == &sched_lock); 975 976 if (td != newtd) { 977 #ifdef HWPMC_HOOKS 978 if (PMC_PROC_IS_USING_PMCS(td->td_proc)) 979 PMC_SWITCH_CONTEXT(td, PMC_FN_CSW_OUT); 980 #endif 981 /* I feel sleepy */ 982 lock_profile_release_lock(&sched_lock.lock_object); 983 #ifdef KDTRACE_HOOKS 984 /* 985 * If DTrace has set the active vtime enum to anything 986 * other than INACTIVE (0), then it should have set the 987 * function to call. 988 */ 989 if (dtrace_vtime_active) 990 (*dtrace_vtime_switch_func)(newtd); 991 #endif 992 993 cpu_switch(td, newtd, td->td_lock); 994 lock_profile_obtain_lock_success(&sched_lock.lock_object, 995 0, 0, __FILE__, __LINE__); 996 /* 997 * Where am I? What year is it? 998 * We are in the same thread that went to sleep above, 999 * but any amount of time may have passed. All our context 1000 * will still be available as will local variables. 1001 * PCPU values however may have changed as we may have 1002 * changed CPU so don't trust cached values of them. 1003 * New threads will go to fork_exit() instead of here 1004 * so if you change things here you may need to change 1005 * things there too. 1006 * 1007 * If the thread above was exiting it will never wake 1008 * up again here, so either it has saved everything it 1009 * needed to, or the thread_wait() or wait() will 1010 * need to reap it. 1011 */ 1012 #ifdef HWPMC_HOOKS 1013 if (PMC_PROC_IS_USING_PMCS(td->td_proc)) 1014 PMC_SWITCH_CONTEXT(td, PMC_FN_CSW_IN); 1015 #endif 1016 } 1017 1018 #ifdef SMP 1019 if (td->td_flags & TDF_IDLETD) 1020 idle_cpus_mask |= PCPU_GET(cpumask); 1021 #endif 1022 sched_lock.mtx_lock = (uintptr_t)td; 1023 td->td_oncpu = PCPU_GET(cpuid); 1024 MPASS(td->td_lock == &sched_lock); 1025 } 1026 1027 void 1028 sched_wakeup(struct thread *td) 1029 { 1030 struct td_sched *ts; 1031 1032 THREAD_LOCK_ASSERT(td, MA_OWNED); 1033 ts = td->td_sched; 1034 td->td_flags &= ~TDF_CANSWAP; 1035 if (ts->ts_slptime > 1) { 1036 updatepri(td); 1037 resetpriority(td); 1038 } 1039 td->td_slptick = ticks; 1040 ts->ts_slptime = 0; 1041 sched_add(td, SRQ_BORING); 1042 } 1043 1044 #ifdef SMP 1045 static int 1046 forward_wakeup(int cpunum) 1047 { 1048 struct pcpu *pc; 1049 cpumask_t dontuse, id, map, map2, map3, me; 1050 1051 mtx_assert(&sched_lock, MA_OWNED); 1052 1053 CTR0(KTR_RUNQ, "forward_wakeup()"); 1054 1055 if ((!forward_wakeup_enabled) || 1056 (forward_wakeup_use_mask == 0 && forward_wakeup_use_loop == 0)) 1057 return (0); 1058 if (!smp_started || cold || panicstr) 1059 return (0); 1060 1061 forward_wakeups_requested++; 1062 1063 /* 1064 * Check the idle mask we received against what we calculated 1065 * before in the old version. 1066 */ 1067 me = PCPU_GET(cpumask); 1068 1069 /* Don't bother if we should be doing it ourself. */ 1070 if ((me & idle_cpus_mask) && (cpunum == NOCPU || me == (1 << cpunum))) 1071 return (0); 1072 1073 dontuse = me | stopped_cpus | hlt_cpus_mask; 1074 map3 = 0; 1075 if (forward_wakeup_use_loop) { 1076 SLIST_FOREACH(pc, &cpuhead, pc_allcpu) { 1077 id = pc->pc_cpumask; 1078 if ((id & dontuse) == 0 && 1079 pc->pc_curthread == pc->pc_idlethread) { 1080 map3 |= id; 1081 } 1082 } 1083 } 1084 1085 if (forward_wakeup_use_mask) { 1086 map = 0; 1087 map = idle_cpus_mask & ~dontuse; 1088 1089 /* If they are both on, compare and use loop if different. */ 1090 if (forward_wakeup_use_loop) { 1091 if (map != map3) { 1092 printf("map (%02X) != map3 (%02X)\n", map, 1093 map3); 1094 map = map3; 1095 } 1096 } 1097 } else { 1098 map = map3; 1099 } 1100 1101 /* If we only allow a specific CPU, then mask off all the others. */ 1102 if (cpunum != NOCPU) { 1103 KASSERT((cpunum <= mp_maxcpus),("forward_wakeup: bad cpunum.")); 1104 map &= (1 << cpunum); 1105 } else { 1106 /* Try choose an idle die. */ 1107 if (forward_wakeup_use_htt) { 1108 map2 = (map & (map >> 1)) & 0x5555; 1109 if (map2) { 1110 map = map2; 1111 } 1112 } 1113 1114 /* Set only one bit. */ 1115 if (forward_wakeup_use_single) { 1116 map = map & ((~map) + 1); 1117 } 1118 } 1119 if (map) { 1120 forward_wakeups_delivered++; 1121 ipi_selected(map, IPI_AST); 1122 return (1); 1123 } 1124 if (cpunum == NOCPU) 1125 printf("forward_wakeup: Idle processor not found\n"); 1126 return (0); 1127 } 1128 1129 static void 1130 kick_other_cpu(int pri, int cpuid) 1131 { 1132 struct pcpu *pcpu; 1133 int cpri; 1134 1135 pcpu = pcpu_find(cpuid); 1136 if (idle_cpus_mask & pcpu->pc_cpumask) { 1137 forward_wakeups_delivered++; 1138 ipi_selected(pcpu->pc_cpumask, IPI_AST); 1139 return; 1140 } 1141 1142 cpri = pcpu->pc_curthread->td_priority; 1143 if (pri >= cpri) 1144 return; 1145 1146 #if defined(IPI_PREEMPTION) && defined(PREEMPTION) 1147 #if !defined(FULL_PREEMPTION) 1148 if (pri <= PRI_MAX_ITHD) 1149 #endif /* ! FULL_PREEMPTION */ 1150 { 1151 ipi_selected(pcpu->pc_cpumask, IPI_PREEMPT); 1152 return; 1153 } 1154 #endif /* defined(IPI_PREEMPTION) && defined(PREEMPTION) */ 1155 1156 pcpu->pc_curthread->td_flags |= TDF_NEEDRESCHED; 1157 ipi_selected(pcpu->pc_cpumask, IPI_AST); 1158 return; 1159 } 1160 #endif /* SMP */ 1161 1162 #ifdef SMP 1163 static int 1164 sched_pickcpu(struct thread *td) 1165 { 1166 int best, cpu; 1167 1168 mtx_assert(&sched_lock, MA_OWNED); 1169 1170 if (THREAD_CAN_SCHED(td, td->td_lastcpu)) 1171 best = td->td_lastcpu; 1172 else 1173 best = NOCPU; 1174 for (cpu = 0; cpu <= mp_maxid; cpu++) { 1175 if (CPU_ABSENT(cpu)) 1176 continue; 1177 if (!THREAD_CAN_SCHED(td, cpu)) 1178 continue; 1179 1180 if (best == NOCPU) 1181 best = cpu; 1182 else if (runq_length[cpu] < runq_length[best]) 1183 best = cpu; 1184 } 1185 KASSERT(best != NOCPU, ("no valid CPUs")); 1186 1187 return (best); 1188 } 1189 #endif 1190 1191 void 1192 sched_add(struct thread *td, int flags) 1193 #ifdef SMP 1194 { 1195 struct td_sched *ts; 1196 int forwarded = 0; 1197 int cpu; 1198 int single_cpu = 0; 1199 1200 ts = td->td_sched; 1201 THREAD_LOCK_ASSERT(td, MA_OWNED); 1202 KASSERT((td->td_inhibitors == 0), 1203 ("sched_add: trying to run inhibited thread")); 1204 KASSERT((TD_CAN_RUN(td) || TD_IS_RUNNING(td)), 1205 ("sched_add: bad thread state")); 1206 KASSERT(td->td_flags & TDF_INMEM, 1207 ("sched_add: thread swapped out")); 1208 CTR5(KTR_SCHED, "sched_add: %p(%s) prio %d by %p(%s)", 1209 td, td->td_name, td->td_priority, curthread, 1210 curthread->td_name); 1211 1212 /* 1213 * Now that the thread is moving to the run-queue, set the lock 1214 * to the scheduler's lock. 1215 */ 1216 if (td->td_lock != &sched_lock) { 1217 mtx_lock_spin(&sched_lock); 1218 thread_lock_set(td, &sched_lock); 1219 } 1220 TD_SET_RUNQ(td); 1221 1222 if (td->td_pinned != 0) { 1223 cpu = td->td_lastcpu; 1224 ts->ts_runq = &runq_pcpu[cpu]; 1225 single_cpu = 1; 1226 CTR3(KTR_RUNQ, 1227 "sched_add: Put td_sched:%p(td:%p) on cpu%d runq", ts, td, 1228 cpu); 1229 } else if (td->td_flags & TDF_BOUND) { 1230 /* Find CPU from bound runq. */ 1231 KASSERT(SKE_RUNQ_PCPU(ts), 1232 ("sched_add: bound td_sched not on cpu runq")); 1233 cpu = ts->ts_runq - &runq_pcpu[0]; 1234 single_cpu = 1; 1235 CTR3(KTR_RUNQ, 1236 "sched_add: Put td_sched:%p(td:%p) on cpu%d runq", ts, td, 1237 cpu); 1238 } else if (ts->ts_flags & TSF_AFFINITY) { 1239 /* Find a valid CPU for our cpuset */ 1240 cpu = sched_pickcpu(td); 1241 ts->ts_runq = &runq_pcpu[cpu]; 1242 single_cpu = 1; 1243 CTR3(KTR_RUNQ, 1244 "sched_add: Put td_sched:%p(td:%p) on cpu%d runq", ts, td, 1245 cpu); 1246 } else { 1247 CTR2(KTR_RUNQ, 1248 "sched_add: adding td_sched:%p (td:%p) to gbl runq", ts, 1249 td); 1250 cpu = NOCPU; 1251 ts->ts_runq = &runq; 1252 } 1253 1254 if (single_cpu && (cpu != PCPU_GET(cpuid))) { 1255 kick_other_cpu(td->td_priority, cpu); 1256 } else { 1257 if (!single_cpu) { 1258 cpumask_t me = PCPU_GET(cpumask); 1259 cpumask_t idle = idle_cpus_mask & me; 1260 1261 if (!idle && ((flags & SRQ_INTR) == 0) && 1262 (idle_cpus_mask & ~(hlt_cpus_mask | me))) 1263 forwarded = forward_wakeup(cpu); 1264 } 1265 1266 if (!forwarded) { 1267 if ((flags & SRQ_YIELDING) == 0 && maybe_preempt(td)) 1268 return; 1269 else 1270 maybe_resched(td); 1271 } 1272 } 1273 1274 if ((td->td_proc->p_flag & P_NOLOAD) == 0) 1275 sched_load_add(); 1276 runq_add(ts->ts_runq, td, flags); 1277 if (cpu != NOCPU) 1278 runq_length[cpu]++; 1279 } 1280 #else /* SMP */ 1281 { 1282 struct td_sched *ts; 1283 1284 ts = td->td_sched; 1285 THREAD_LOCK_ASSERT(td, MA_OWNED); 1286 KASSERT((td->td_inhibitors == 0), 1287 ("sched_add: trying to run inhibited thread")); 1288 KASSERT((TD_CAN_RUN(td) || TD_IS_RUNNING(td)), 1289 ("sched_add: bad thread state")); 1290 KASSERT(td->td_flags & TDF_INMEM, 1291 ("sched_add: thread swapped out")); 1292 CTR5(KTR_SCHED, "sched_add: %p(%s) prio %d by %p(%s)", 1293 td, td->td_name, td->td_priority, curthread, 1294 curthread->td_name); 1295 1296 /* 1297 * Now that the thread is moving to the run-queue, set the lock 1298 * to the scheduler's lock. 1299 */ 1300 if (td->td_lock != &sched_lock) { 1301 mtx_lock_spin(&sched_lock); 1302 thread_lock_set(td, &sched_lock); 1303 } 1304 TD_SET_RUNQ(td); 1305 CTR2(KTR_RUNQ, "sched_add: adding td_sched:%p (td:%p) to runq", ts, td); 1306 ts->ts_runq = &runq; 1307 1308 /* 1309 * If we are yielding (on the way out anyhow) or the thread 1310 * being saved is US, then don't try be smart about preemption 1311 * or kicking off another CPU as it won't help and may hinder. 1312 * In the YIEDLING case, we are about to run whoever is being 1313 * put in the queue anyhow, and in the OURSELF case, we are 1314 * puting ourself on the run queue which also only happens 1315 * when we are about to yield. 1316 */ 1317 if ((flags & SRQ_YIELDING) == 0) { 1318 if (maybe_preempt(td)) 1319 return; 1320 } 1321 if ((td->td_proc->p_flag & P_NOLOAD) == 0) 1322 sched_load_add(); 1323 runq_add(ts->ts_runq, td, flags); 1324 maybe_resched(td); 1325 } 1326 #endif /* SMP */ 1327 1328 void 1329 sched_rem(struct thread *td) 1330 { 1331 struct td_sched *ts; 1332 1333 ts = td->td_sched; 1334 KASSERT(td->td_flags & TDF_INMEM, 1335 ("sched_rem: thread swapped out")); 1336 KASSERT(TD_ON_RUNQ(td), 1337 ("sched_rem: thread not on run queue")); 1338 mtx_assert(&sched_lock, MA_OWNED); 1339 CTR5(KTR_SCHED, "sched_rem: %p(%s) prio %d by %p(%s)", 1340 td, td->td_name, td->td_priority, curthread, 1341 curthread->td_name); 1342 1343 if ((td->td_proc->p_flag & P_NOLOAD) == 0) 1344 sched_load_rem(); 1345 #ifdef SMP 1346 if (ts->ts_runq != &runq) 1347 runq_length[ts->ts_runq - runq_pcpu]--; 1348 #endif 1349 runq_remove(ts->ts_runq, td); 1350 TD_SET_CAN_RUN(td); 1351 } 1352 1353 /* 1354 * Select threads to run. Note that running threads still consume a 1355 * slot. 1356 */ 1357 struct thread * 1358 sched_choose(void) 1359 { 1360 struct thread *td; 1361 struct runq *rq; 1362 1363 mtx_assert(&sched_lock, MA_OWNED); 1364 #ifdef SMP 1365 struct thread *tdcpu; 1366 1367 rq = &runq; 1368 td = runq_choose_fuzz(&runq, runq_fuzz); 1369 tdcpu = runq_choose(&runq_pcpu[PCPU_GET(cpuid)]); 1370 1371 if (td == NULL || 1372 (tdcpu != NULL && 1373 tdcpu->td_priority < td->td_priority)) { 1374 CTR2(KTR_RUNQ, "choosing td %p from pcpu runq %d", tdcpu, 1375 PCPU_GET(cpuid)); 1376 td = tdcpu; 1377 rq = &runq_pcpu[PCPU_GET(cpuid)]; 1378 } else { 1379 CTR1(KTR_RUNQ, "choosing td_sched %p from main runq", td); 1380 } 1381 1382 #else 1383 rq = &runq; 1384 td = runq_choose(&runq); 1385 #endif 1386 1387 if (td) { 1388 #ifdef SMP 1389 if (td == tdcpu) 1390 runq_length[PCPU_GET(cpuid)]--; 1391 #endif 1392 runq_remove(rq, td); 1393 td->td_flags |= TDF_DIDRUN; 1394 1395 KASSERT(td->td_flags & TDF_INMEM, 1396 ("sched_choose: thread swapped out")); 1397 return (td); 1398 } 1399 return (PCPU_GET(idlethread)); 1400 } 1401 1402 void 1403 sched_preempt(struct thread *td) 1404 { 1405 thread_lock(td); 1406 if (td->td_critnest > 1) 1407 td->td_owepreempt = 1; 1408 else 1409 mi_switch(SW_INVOL | SW_PREEMPT | SWT_PREEMPT, NULL); 1410 thread_unlock(td); 1411 } 1412 1413 void 1414 sched_userret(struct thread *td) 1415 { 1416 /* 1417 * XXX we cheat slightly on the locking here to avoid locking in 1418 * the usual case. Setting td_priority here is essentially an 1419 * incomplete workaround for not setting it properly elsewhere. 1420 * Now that some interrupt handlers are threads, not setting it 1421 * properly elsewhere can clobber it in the window between setting 1422 * it here and returning to user mode, so don't waste time setting 1423 * it perfectly here. 1424 */ 1425 KASSERT((td->td_flags & TDF_BORROWING) == 0, 1426 ("thread with borrowed priority returning to userland")); 1427 if (td->td_priority != td->td_user_pri) { 1428 thread_lock(td); 1429 td->td_priority = td->td_user_pri; 1430 td->td_base_pri = td->td_user_pri; 1431 thread_unlock(td); 1432 } 1433 } 1434 1435 void 1436 sched_bind(struct thread *td, int cpu) 1437 { 1438 struct td_sched *ts; 1439 1440 THREAD_LOCK_ASSERT(td, MA_OWNED); 1441 KASSERT(TD_IS_RUNNING(td), 1442 ("sched_bind: cannot bind non-running thread")); 1443 1444 ts = td->td_sched; 1445 1446 td->td_flags |= TDF_BOUND; 1447 #ifdef SMP 1448 ts->ts_runq = &runq_pcpu[cpu]; 1449 if (PCPU_GET(cpuid) == cpu) 1450 return; 1451 1452 mi_switch(SW_VOL, NULL); 1453 #endif 1454 } 1455 1456 void 1457 sched_unbind(struct thread* td) 1458 { 1459 THREAD_LOCK_ASSERT(td, MA_OWNED); 1460 td->td_flags &= ~TDF_BOUND; 1461 } 1462 1463 int 1464 sched_is_bound(struct thread *td) 1465 { 1466 THREAD_LOCK_ASSERT(td, MA_OWNED); 1467 return (td->td_flags & TDF_BOUND); 1468 } 1469 1470 void 1471 sched_relinquish(struct thread *td) 1472 { 1473 thread_lock(td); 1474 mi_switch(SW_VOL | SWT_RELINQUISH, NULL); 1475 thread_unlock(td); 1476 } 1477 1478 int 1479 sched_load(void) 1480 { 1481 return (sched_tdcnt); 1482 } 1483 1484 int 1485 sched_sizeof_proc(void) 1486 { 1487 return (sizeof(struct proc)); 1488 } 1489 1490 int 1491 sched_sizeof_thread(void) 1492 { 1493 return (sizeof(struct thread) + sizeof(struct td_sched)); 1494 } 1495 1496 fixpt_t 1497 sched_pctcpu(struct thread *td) 1498 { 1499 struct td_sched *ts; 1500 1501 ts = td->td_sched; 1502 return (ts->ts_pctcpu); 1503 } 1504 1505 void 1506 sched_tick(void) 1507 { 1508 } 1509 1510 /* 1511 * The actual idle process. 1512 */ 1513 void 1514 sched_idletd(void *dummy) 1515 { 1516 1517 for (;;) { 1518 mtx_assert(&Giant, MA_NOTOWNED); 1519 1520 while (sched_runnable() == 0) 1521 cpu_idle(0); 1522 1523 mtx_lock_spin(&sched_lock); 1524 mi_switch(SW_VOL | SWT_IDLE, NULL); 1525 mtx_unlock_spin(&sched_lock); 1526 } 1527 } 1528 1529 /* 1530 * A CPU is entering for the first time or a thread is exiting. 1531 */ 1532 void 1533 sched_throw(struct thread *td) 1534 { 1535 /* 1536 * Correct spinlock nesting. The idle thread context that we are 1537 * borrowing was created so that it would start out with a single 1538 * spin lock (sched_lock) held in fork_trampoline(). Since we've 1539 * explicitly acquired locks in this function, the nesting count 1540 * is now 2 rather than 1. Since we are nested, calling 1541 * spinlock_exit() will simply adjust the counts without allowing 1542 * spin lock using code to interrupt us. 1543 */ 1544 if (td == NULL) { 1545 mtx_lock_spin(&sched_lock); 1546 spinlock_exit(); 1547 } else { 1548 lock_profile_release_lock(&sched_lock.lock_object); 1549 MPASS(td->td_lock == &sched_lock); 1550 } 1551 mtx_assert(&sched_lock, MA_OWNED); 1552 KASSERT(curthread->td_md.md_spinlock_count == 1, ("invalid count")); 1553 PCPU_SET(switchtime, cpu_ticks()); 1554 PCPU_SET(switchticks, ticks); 1555 cpu_throw(td, choosethread()); /* doesn't return */ 1556 } 1557 1558 void 1559 sched_fork_exit(struct thread *td) 1560 { 1561 1562 /* 1563 * Finish setting up thread glue so that it begins execution in a 1564 * non-nested critical section with sched_lock held but not recursed. 1565 */ 1566 td->td_oncpu = PCPU_GET(cpuid); 1567 sched_lock.mtx_lock = (uintptr_t)td; 1568 lock_profile_obtain_lock_success(&sched_lock.lock_object, 1569 0, 0, __FILE__, __LINE__); 1570 THREAD_LOCK_ASSERT(td, MA_OWNED | MA_NOTRECURSED); 1571 } 1572 1573 void 1574 sched_affinity(struct thread *td) 1575 { 1576 #ifdef SMP 1577 struct td_sched *ts; 1578 int cpu; 1579 1580 THREAD_LOCK_ASSERT(td, MA_OWNED); 1581 1582 /* 1583 * Set the TSF_AFFINITY flag if there is at least one CPU this 1584 * thread can't run on. 1585 */ 1586 ts = td->td_sched; 1587 ts->ts_flags &= ~TSF_AFFINITY; 1588 for (cpu = 0; cpu <= mp_maxid; cpu++) { 1589 if (CPU_ABSENT(cpu)) 1590 continue; 1591 if (!THREAD_CAN_SCHED(td, cpu)) { 1592 ts->ts_flags |= TSF_AFFINITY; 1593 break; 1594 } 1595 } 1596 1597 /* 1598 * If this thread can run on all CPUs, nothing else to do. 1599 */ 1600 if (!(ts->ts_flags & TSF_AFFINITY)) 1601 return; 1602 1603 /* Pinned threads and bound threads should be left alone. */ 1604 if (td->td_pinned != 0 || td->td_flags & TDF_BOUND) 1605 return; 1606 1607 switch (td->td_state) { 1608 case TDS_RUNQ: 1609 /* 1610 * If we are on a per-CPU runqueue that is in the set, 1611 * then nothing needs to be done. 1612 */ 1613 if (ts->ts_runq != &runq && 1614 THREAD_CAN_SCHED(td, ts->ts_runq - runq_pcpu)) 1615 return; 1616 1617 /* Put this thread on a valid per-CPU runqueue. */ 1618 sched_rem(td); 1619 sched_add(td, SRQ_BORING); 1620 break; 1621 case TDS_RUNNING: 1622 /* 1623 * See if our current CPU is in the set. If not, force a 1624 * context switch. 1625 */ 1626 if (THREAD_CAN_SCHED(td, td->td_oncpu)) 1627 return; 1628 1629 td->td_flags |= TDF_NEEDRESCHED; 1630 if (td != curthread) 1631 ipi_selected(1 << cpu, IPI_AST); 1632 break; 1633 default: 1634 break; 1635 } 1636 #endif 1637 } 1638