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: stable/11/sys/kern/sched_4bsd.c 331722 2018-03-29 02:50:57Z eadler $"); 37 38#include "opt_hwpmc_hooks.h" 39#include "opt_sched.h" 40 41#include <sys/param.h> 42#include <sys/systm.h> 43#include <sys/cpuset.h> 44#include <sys/kernel.h> 45#include <sys/ktr.h> 46#include <sys/lock.h> 47#include <sys/kthread.h> 48#include <sys/mutex.h> 49#include <sys/proc.h> 50#include <sys/resourcevar.h> 51#include <sys/sched.h> 52#include <sys/sdt.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> 67int dtrace_vtime_active; 68dtrace_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 * All fields are protected by the scheduler lock. 92 */ 93struct td_sched { 94 fixpt_t ts_pctcpu; /* %cpu during p_swtime. */ 95 u_int ts_estcpu; /* Estimated cpu utilization. */ 96 int ts_cpticks; /* Ticks of cpu time. */ 97 int ts_slptime; /* Seconds !RUNNING. */ 98 int ts_slice; /* Remaining part of time slice. */ 99 int ts_flags; 100 struct runq *ts_runq; /* runq the thread is currently on */ 101#ifdef KTR 102 char ts_name[TS_NAME_LEN]; 103#endif 104}; 105 106/* flags kept in td_flags */ 107#define TDF_DIDRUN TDF_SCHED0 /* thread actually ran. */ 108#define TDF_BOUND TDF_SCHED1 /* Bound to one CPU. */ 109#define TDF_SLICEEND TDF_SCHED2 /* Thread time slice is over. */ 110 111/* flags kept in ts_flags */ 112#define TSF_AFFINITY 0x0001 /* Has a non-"full" CPU set. */ 113 114#define SKE_RUNQ_PCPU(ts) \ 115 ((ts)->ts_runq != 0 && (ts)->ts_runq != &runq) 116 117#define THREAD_CAN_SCHED(td, cpu) \ 118 CPU_ISSET((cpu), &(td)->td_cpuset->cs_mask) 119 120_Static_assert(sizeof(struct thread) + sizeof(struct td_sched) <= 121 sizeof(struct thread0_storage), 122 "increase struct thread0_storage.t0st_sched size"); 123 124static struct mtx sched_lock; 125 126static int realstathz = 127; /* stathz is sometimes 0 and run off of hz. */ 127static int sched_tdcnt; /* Total runnable threads in the system. */ 128static int sched_slice = 12; /* Thread run time before rescheduling. */ 129 130static void setup_runqs(void); 131static void schedcpu(void); 132static void schedcpu_thread(void); 133static void sched_priority(struct thread *td, u_char prio); 134static void sched_setup(void *dummy); 135static void maybe_resched(struct thread *td); 136static void updatepri(struct thread *td); 137static void resetpriority(struct thread *td); 138static void resetpriority_thread(struct thread *td); 139#ifdef SMP 140static int sched_pickcpu(struct thread *td); 141static int forward_wakeup(int cpunum); 142static void kick_other_cpu(int pri, int cpuid); 143#endif 144 145static struct kproc_desc sched_kp = { 146 "schedcpu", 147 schedcpu_thread, 148 NULL 149}; 150SYSINIT(schedcpu, SI_SUB_LAST, SI_ORDER_FIRST, kproc_start, 151 &sched_kp); 152SYSINIT(sched_setup, SI_SUB_RUN_QUEUE, SI_ORDER_FIRST, sched_setup, NULL); 153 154static void sched_initticks(void *dummy); 155SYSINIT(sched_initticks, SI_SUB_CLOCKS, SI_ORDER_THIRD, sched_initticks, 156 NULL); 157 158/* 159 * Global run queue. 160 */ 161static struct runq runq; 162 163#ifdef SMP 164/* 165 * Per-CPU run queues 166 */ 167static struct runq runq_pcpu[MAXCPU]; 168long runq_length[MAXCPU]; 169 170static cpuset_t idle_cpus_mask; 171#endif 172 173struct pcpuidlestat { 174 u_int idlecalls; 175 u_int oldidlecalls; 176}; 177static DPCPU_DEFINE(struct pcpuidlestat, idlestat); 178 179static void 180setup_runqs(void) 181{ 182#ifdef SMP 183 int i; 184 185 for (i = 0; i < MAXCPU; ++i) 186 runq_init(&runq_pcpu[i]); 187#endif 188 189 runq_init(&runq); 190} 191 192static int 193sysctl_kern_quantum(SYSCTL_HANDLER_ARGS) 194{ 195 int error, new_val, period; 196 197 period = 1000000 / realstathz; 198 new_val = period * sched_slice; 199 error = sysctl_handle_int(oidp, &new_val, 0, req); 200 if (error != 0 || req->newptr == NULL) 201 return (error); 202 if (new_val <= 0) 203 return (EINVAL); 204 sched_slice = imax(1, (new_val + period / 2) / period); 205 hogticks = imax(1, (2 * hz * sched_slice + realstathz / 2) / 206 realstathz); 207 return (0); 208} 209 210SYSCTL_NODE(_kern, OID_AUTO, sched, CTLFLAG_RD, 0, "Scheduler"); 211 212SYSCTL_STRING(_kern_sched, OID_AUTO, name, CTLFLAG_RD, "4BSD", 0, 213 "Scheduler name"); 214SYSCTL_PROC(_kern_sched, OID_AUTO, quantum, CTLTYPE_INT | CTLFLAG_RW, 215 NULL, 0, sysctl_kern_quantum, "I", 216 "Quantum for timeshare threads in microseconds"); 217SYSCTL_INT(_kern_sched, OID_AUTO, slice, CTLFLAG_RW, &sched_slice, 0, 218 "Quantum for timeshare threads in stathz ticks"); 219#ifdef SMP 220/* Enable forwarding of wakeups to all other cpus */ 221static SYSCTL_NODE(_kern_sched, OID_AUTO, ipiwakeup, CTLFLAG_RD, NULL, 222 "Kernel SMP"); 223 224static int runq_fuzz = 1; 225SYSCTL_INT(_kern_sched, OID_AUTO, runq_fuzz, CTLFLAG_RW, &runq_fuzz, 0, ""); 226 227static int forward_wakeup_enabled = 1; 228SYSCTL_INT(_kern_sched_ipiwakeup, OID_AUTO, enabled, CTLFLAG_RW, 229 &forward_wakeup_enabled, 0, 230 "Forwarding of wakeup to idle CPUs"); 231 232static int forward_wakeups_requested = 0; 233SYSCTL_INT(_kern_sched_ipiwakeup, OID_AUTO, requested, CTLFLAG_RD, 234 &forward_wakeups_requested, 0, 235 "Requests for Forwarding of wakeup to idle CPUs"); 236 237static int forward_wakeups_delivered = 0; 238SYSCTL_INT(_kern_sched_ipiwakeup, OID_AUTO, delivered, CTLFLAG_RD, 239 &forward_wakeups_delivered, 0, 240 "Completed Forwarding of wakeup to idle CPUs"); 241 242static int forward_wakeup_use_mask = 1; 243SYSCTL_INT(_kern_sched_ipiwakeup, OID_AUTO, usemask, CTLFLAG_RW, 244 &forward_wakeup_use_mask, 0, 245 "Use the mask of idle cpus"); 246 247static int forward_wakeup_use_loop = 0; 248SYSCTL_INT(_kern_sched_ipiwakeup, OID_AUTO, useloop, CTLFLAG_RW, 249 &forward_wakeup_use_loop, 0, 250 "Use a loop to find idle cpus"); 251 252#endif 253#if 0 254static int sched_followon = 0; 255SYSCTL_INT(_kern_sched, OID_AUTO, followon, CTLFLAG_RW, 256 &sched_followon, 0, 257 "allow threads to share a quantum"); 258#endif 259 260SDT_PROVIDER_DEFINE(sched); 261 262SDT_PROBE_DEFINE3(sched, , , change__pri, "struct thread *", 263 "struct proc *", "uint8_t"); 264SDT_PROBE_DEFINE3(sched, , , dequeue, "struct thread *", 265 "struct proc *", "void *"); 266SDT_PROBE_DEFINE4(sched, , , enqueue, "struct thread *", 267 "struct proc *", "void *", "int"); 268SDT_PROBE_DEFINE4(sched, , , lend__pri, "struct thread *", 269 "struct proc *", "uint8_t", "struct thread *"); 270SDT_PROBE_DEFINE2(sched, , , load__change, "int", "int"); 271SDT_PROBE_DEFINE2(sched, , , off__cpu, "struct thread *", 272 "struct proc *"); 273SDT_PROBE_DEFINE(sched, , , on__cpu); 274SDT_PROBE_DEFINE(sched, , , remain__cpu); 275SDT_PROBE_DEFINE2(sched, , , surrender, "struct thread *", 276 "struct proc *"); 277 278static __inline void 279sched_load_add(void) 280{ 281 282 sched_tdcnt++; 283 KTR_COUNTER0(KTR_SCHED, "load", "global load", sched_tdcnt); 284 SDT_PROBE2(sched, , , load__change, NOCPU, sched_tdcnt); 285} 286 287static __inline void 288sched_load_rem(void) 289{ 290 291 sched_tdcnt--; 292 KTR_COUNTER0(KTR_SCHED, "load", "global load", sched_tdcnt); 293 SDT_PROBE2(sched, , , load__change, NOCPU, sched_tdcnt); 294} 295/* 296 * Arrange to reschedule if necessary, taking the priorities and 297 * schedulers into account. 298 */ 299static void 300maybe_resched(struct thread *td) 301{ 302 303 THREAD_LOCK_ASSERT(td, MA_OWNED); 304 if (td->td_priority < curthread->td_priority) 305 curthread->td_flags |= TDF_NEEDRESCHED; 306} 307 308/* 309 * This function is called when a thread is about to be put on run queue 310 * because it has been made runnable or its priority has been adjusted. It 311 * determines if the new thread should preempt the current thread. If so, 312 * it sets td_owepreempt to request a preemption. 313 */ 314int 315maybe_preempt(struct thread *td) 316{ 317#ifdef PREEMPTION 318 struct thread *ctd; 319 int cpri, pri; 320 321 /* 322 * The new thread should not preempt the current thread if any of the 323 * following conditions are true: 324 * 325 * - The kernel is in the throes of crashing (panicstr). 326 * - The current thread has a higher (numerically lower) or 327 * equivalent priority. Note that this prevents curthread from 328 * trying to preempt to itself. 329 * - The current thread has an inhibitor set or is in the process of 330 * exiting. In this case, the current thread is about to switch 331 * out anyways, so there's no point in preempting. If we did, 332 * the current thread would not be properly resumed as well, so 333 * just avoid that whole landmine. 334 * - If the new thread's priority is not a realtime priority and 335 * the current thread's priority is not an idle priority and 336 * FULL_PREEMPTION is disabled. 337 * 338 * If all of these conditions are false, but the current thread is in 339 * a nested critical section, then we have to defer the preemption 340 * until we exit the critical section. Otherwise, switch immediately 341 * to the new thread. 342 */ 343 ctd = curthread; 344 THREAD_LOCK_ASSERT(td, MA_OWNED); 345 KASSERT((td->td_inhibitors == 0), 346 ("maybe_preempt: trying to run inhibited thread")); 347 pri = td->td_priority; 348 cpri = ctd->td_priority; 349 if (panicstr != NULL || pri >= cpri /* || dumping */ || 350 TD_IS_INHIBITED(ctd)) 351 return (0); 352#ifndef FULL_PREEMPTION 353 if (pri > PRI_MAX_ITHD && cpri < PRI_MIN_IDLE) 354 return (0); 355#endif 356 357 CTR0(KTR_PROC, "maybe_preempt: scheduling preemption"); 358 ctd->td_owepreempt = 1; 359 return (1); 360#else 361 return (0); 362#endif 363} 364 365/* 366 * Constants for digital decay and forget: 367 * 90% of (ts_estcpu) usage in 5 * loadav time 368 * 95% of (ts_pctcpu) usage in 60 seconds (load insensitive) 369 * Note that, as ps(1) mentions, this can let percentages 370 * total over 100% (I've seen 137.9% for 3 processes). 371 * 372 * Note that schedclock() updates ts_estcpu and p_cpticks asynchronously. 373 * 374 * We wish to decay away 90% of ts_estcpu in (5 * loadavg) seconds. 375 * That is, the system wants to compute a value of decay such 376 * that the following for loop: 377 * for (i = 0; i < (5 * loadavg); i++) 378 * ts_estcpu *= decay; 379 * will compute 380 * ts_estcpu *= 0.1; 381 * for all values of loadavg: 382 * 383 * Mathematically this loop can be expressed by saying: 384 * decay ** (5 * loadavg) ~= .1 385 * 386 * The system computes decay as: 387 * decay = (2 * loadavg) / (2 * loadavg + 1) 388 * 389 * We wish to prove that the system's computation of decay 390 * will always fulfill the equation: 391 * decay ** (5 * loadavg) ~= .1 392 * 393 * If we compute b as: 394 * b = 2 * loadavg 395 * then 396 * decay = b / (b + 1) 397 * 398 * We now need to prove two things: 399 * 1) Given factor ** (5 * loadavg) ~= .1, prove factor == b/(b+1) 400 * 2) Given b/(b+1) ** power ~= .1, prove power == (5 * loadavg) 401 * 402 * Facts: 403 * For x close to zero, exp(x) =~ 1 + x, since 404 * exp(x) = 0! + x**1/1! + x**2/2! + ... . 405 * therefore exp(-1/b) =~ 1 - (1/b) = (b-1)/b. 406 * For x close to zero, ln(1+x) =~ x, since 407 * ln(1+x) = x - x**2/2 + x**3/3 - ... -1 < x < 1 408 * therefore ln(b/(b+1)) = ln(1 - 1/(b+1)) =~ -1/(b+1). 409 * ln(.1) =~ -2.30 410 * 411 * Proof of (1): 412 * Solve (factor)**(power) =~ .1 given power (5*loadav): 413 * solving for factor, 414 * ln(factor) =~ (-2.30/5*loadav), or 415 * factor =~ exp(-1/((5/2.30)*loadav)) =~ exp(-1/(2*loadav)) = 416 * exp(-1/b) =~ (b-1)/b =~ b/(b+1). QED 417 * 418 * Proof of (2): 419 * Solve (factor)**(power) =~ .1 given factor == (b/(b+1)): 420 * solving for power, 421 * power*ln(b/(b+1)) =~ -2.30, or 422 * power =~ 2.3 * (b + 1) = 4.6*loadav + 2.3 =~ 5*loadav. QED 423 * 424 * Actual power values for the implemented algorithm are as follows: 425 * loadav: 1 2 3 4 426 * power: 5.68 10.32 14.94 19.55 427 */ 428 429/* calculations for digital decay to forget 90% of usage in 5*loadav sec */ 430#define loadfactor(loadav) (2 * (loadav)) 431#define decay_cpu(loadfac, cpu) (((loadfac) * (cpu)) / ((loadfac) + FSCALE)) 432 433/* decay 95% of `ts_pctcpu' in 60 seconds; see CCPU_SHIFT before changing */ 434static fixpt_t ccpu = 0.95122942450071400909 * FSCALE; /* exp(-1/20) */ 435SYSCTL_UINT(_kern, OID_AUTO, ccpu, CTLFLAG_RD, &ccpu, 0, ""); 436 437/* 438 * If `ccpu' is not equal to `exp(-1/20)' and you still want to use the 439 * faster/more-accurate formula, you'll have to estimate CCPU_SHIFT below 440 * and possibly adjust FSHIFT in "param.h" so that (FSHIFT >= CCPU_SHIFT). 441 * 442 * To estimate CCPU_SHIFT for exp(-1/20), the following formula was used: 443 * 1 - exp(-1/20) ~= 0.0487 ~= 0.0488 == 1 (fixed pt, *11* bits). 444 * 445 * If you don't want to bother with the faster/more-accurate formula, you 446 * can set CCPU_SHIFT to (FSHIFT + 1) which will use a slower/less-accurate 447 * (more general) method of calculating the %age of CPU used by a process. 448 */ 449#define CCPU_SHIFT 11 450 451/* 452 * Recompute process priorities, every hz ticks. 453 * MP-safe, called without the Giant mutex. 454 */ 455/* ARGSUSED */ 456static void 457schedcpu(void) 458{ 459 fixpt_t loadfac = loadfactor(averunnable.ldavg[0]); 460 struct thread *td; 461 struct proc *p; 462 struct td_sched *ts; 463 int awake; 464 465 sx_slock(&allproc_lock); 466 FOREACH_PROC_IN_SYSTEM(p) { 467 PROC_LOCK(p); 468 if (p->p_state == PRS_NEW) { 469 PROC_UNLOCK(p); 470 continue; 471 } 472 FOREACH_THREAD_IN_PROC(p, td) { 473 awake = 0; 474 ts = td_get_sched(td); 475 thread_lock(td); 476 /* 477 * Increment sleep time (if sleeping). We 478 * ignore overflow, as above. 479 */ 480 /* 481 * The td_sched slptimes are not touched in wakeup 482 * because the thread may not HAVE everything in 483 * memory? XXX I think this is out of date. 484 */ 485 if (TD_ON_RUNQ(td)) { 486 awake = 1; 487 td->td_flags &= ~TDF_DIDRUN; 488 } else if (TD_IS_RUNNING(td)) { 489 awake = 1; 490 /* Do not clear TDF_DIDRUN */ 491 } else if (td->td_flags & TDF_DIDRUN) { 492 awake = 1; 493 td->td_flags &= ~TDF_DIDRUN; 494 } 495 496 /* 497 * ts_pctcpu is only for ps and ttyinfo(). 498 */ 499 ts->ts_pctcpu = (ts->ts_pctcpu * ccpu) >> FSHIFT; 500 /* 501 * If the td_sched has been idle the entire second, 502 * stop recalculating its priority until 503 * it wakes up. 504 */ 505 if (ts->ts_cpticks != 0) { 506#if (FSHIFT >= CCPU_SHIFT) 507 ts->ts_pctcpu += (realstathz == 100) 508 ? ((fixpt_t) ts->ts_cpticks) << 509 (FSHIFT - CCPU_SHIFT) : 510 100 * (((fixpt_t) ts->ts_cpticks) 511 << (FSHIFT - CCPU_SHIFT)) / realstathz; 512#else 513 ts->ts_pctcpu += ((FSCALE - ccpu) * 514 (ts->ts_cpticks * 515 FSCALE / realstathz)) >> FSHIFT; 516#endif 517 ts->ts_cpticks = 0; 518 } 519 /* 520 * If there are ANY running threads in this process, 521 * then don't count it as sleeping. 522 * XXX: this is broken. 523 */ 524 if (awake) { 525 if (ts->ts_slptime > 1) { 526 /* 527 * In an ideal world, this should not 528 * happen, because whoever woke us 529 * up from the long sleep should have 530 * unwound the slptime and reset our 531 * priority before we run at the stale 532 * priority. Should KASSERT at some 533 * point when all the cases are fixed. 534 */ 535 updatepri(td); 536 } 537 ts->ts_slptime = 0; 538 } else 539 ts->ts_slptime++; 540 if (ts->ts_slptime > 1) { 541 thread_unlock(td); 542 continue; 543 } 544 ts->ts_estcpu = decay_cpu(loadfac, ts->ts_estcpu); 545 resetpriority(td); 546 resetpriority_thread(td); 547 thread_unlock(td); 548 } 549 PROC_UNLOCK(p); 550 } 551 sx_sunlock(&allproc_lock); 552} 553 554/* 555 * Main loop for a kthread that executes schedcpu once a second. 556 */ 557static void 558schedcpu_thread(void) 559{ 560 561 for (;;) { 562 schedcpu(); 563 pause("-", hz); 564 } 565} 566 567/* 568 * Recalculate the priority of a process after it has slept for a while. 569 * For all load averages >= 1 and max ts_estcpu of 255, sleeping for at 570 * least six times the loadfactor will decay ts_estcpu to zero. 571 */ 572static void 573updatepri(struct thread *td) 574{ 575 struct td_sched *ts; 576 fixpt_t loadfac; 577 unsigned int newcpu; 578 579 ts = td_get_sched(td); 580 loadfac = loadfactor(averunnable.ldavg[0]); 581 if (ts->ts_slptime > 5 * loadfac) 582 ts->ts_estcpu = 0; 583 else { 584 newcpu = ts->ts_estcpu; 585 ts->ts_slptime--; /* was incremented in schedcpu() */ 586 while (newcpu && --ts->ts_slptime) 587 newcpu = decay_cpu(loadfac, newcpu); 588 ts->ts_estcpu = newcpu; 589 } 590} 591 592/* 593 * Compute the priority of a process when running in user mode. 594 * Arrange to reschedule if the resulting priority is better 595 * than that of the current process. 596 */ 597static void 598resetpriority(struct thread *td) 599{ 600 u_int newpriority; 601 602 if (td->td_pri_class != PRI_TIMESHARE) 603 return; 604 newpriority = PUSER + 605 td_get_sched(td)->ts_estcpu / INVERSE_ESTCPU_WEIGHT + 606 NICE_WEIGHT * (td->td_proc->p_nice - PRIO_MIN); 607 newpriority = min(max(newpriority, PRI_MIN_TIMESHARE), 608 PRI_MAX_TIMESHARE); 609 sched_user_prio(td, newpriority); 610} 611 612/* 613 * Update the thread's priority when the associated process's user 614 * priority changes. 615 */ 616static void 617resetpriority_thread(struct thread *td) 618{ 619 620 /* Only change threads with a time sharing user priority. */ 621 if (td->td_priority < PRI_MIN_TIMESHARE || 622 td->td_priority > PRI_MAX_TIMESHARE) 623 return; 624 625 /* XXX the whole needresched thing is broken, but not silly. */ 626 maybe_resched(td); 627 628 sched_prio(td, td->td_user_pri); 629} 630 631/* ARGSUSED */ 632static void 633sched_setup(void *dummy) 634{ 635 636 setup_runqs(); 637 638 /* Account for thread0. */ 639 sched_load_add(); 640} 641 642/* 643 * This routine determines time constants after stathz and hz are setup. 644 */ 645static void 646sched_initticks(void *dummy) 647{ 648 649 realstathz = stathz ? stathz : hz; 650 sched_slice = realstathz / 10; /* ~100ms */ 651 hogticks = imax(1, (2 * hz * sched_slice + realstathz / 2) / 652 realstathz); 653} 654 655/* External interfaces start here */ 656 657/* 658 * Very early in the boot some setup of scheduler-specific 659 * parts of proc0 and of some scheduler resources needs to be done. 660 * Called from: 661 * proc0_init() 662 */ 663void 664schedinit(void) 665{ 666 667 /* 668 * Set up the scheduler specific parts of thread0. 669 */ 670 thread0.td_lock = &sched_lock; 671 td_get_sched(&thread0)->ts_slice = sched_slice; 672 mtx_init(&sched_lock, "sched lock", NULL, MTX_SPIN | MTX_RECURSE); 673} 674 675int 676sched_runnable(void) 677{ 678#ifdef SMP 679 return runq_check(&runq) + runq_check(&runq_pcpu[PCPU_GET(cpuid)]); 680#else 681 return runq_check(&runq); 682#endif 683} 684 685int 686sched_rr_interval(void) 687{ 688 689 /* Convert sched_slice from stathz to hz. */ 690 return (imax(1, (sched_slice * hz + realstathz / 2) / realstathz)); 691} 692 693/* 694 * We adjust the priority of the current process. The priority of a 695 * process gets worse as it accumulates CPU time. The cpu usage 696 * estimator (ts_estcpu) is increased here. resetpriority() will 697 * compute a different priority each time ts_estcpu increases by 698 * INVERSE_ESTCPU_WEIGHT (until PRI_MAX_TIMESHARE is reached). The 699 * cpu usage estimator ramps up quite quickly when the process is 700 * running (linearly), and decays away exponentially, at a rate which 701 * is proportionally slower when the system is busy. The basic 702 * principle is that the system will 90% forget that the process used 703 * a lot of CPU time in 5 * loadav seconds. This causes the system to 704 * favor processes which haven't run much recently, and to round-robin 705 * among other processes. 706 */ 707void 708sched_clock(struct thread *td) 709{ 710 struct pcpuidlestat *stat; 711 struct td_sched *ts; 712 713 THREAD_LOCK_ASSERT(td, MA_OWNED); 714 ts = td_get_sched(td); 715 716 ts->ts_cpticks++; 717 ts->ts_estcpu = ESTCPULIM(ts->ts_estcpu + 1); 718 if ((ts->ts_estcpu % INVERSE_ESTCPU_WEIGHT) == 0) { 719 resetpriority(td); 720 resetpriority_thread(td); 721 } 722 723 /* 724 * Force a context switch if the current thread has used up a full 725 * time slice (default is 100ms). 726 */ 727 if (!TD_IS_IDLETHREAD(td) && --ts->ts_slice <= 0) { 728 ts->ts_slice = sched_slice; 729 td->td_flags |= TDF_NEEDRESCHED | TDF_SLICEEND; 730 } 731 732 stat = DPCPU_PTR(idlestat); 733 stat->oldidlecalls = stat->idlecalls; 734 stat->idlecalls = 0; 735} 736 737/* 738 * Charge child's scheduling CPU usage to parent. 739 */ 740void 741sched_exit(struct proc *p, struct thread *td) 742{ 743 744 KTR_STATE1(KTR_SCHED, "thread", sched_tdname(td), "proc exit", 745 "prio:%d", td->td_priority); 746 747 PROC_LOCK_ASSERT(p, MA_OWNED); 748 sched_exit_thread(FIRST_THREAD_IN_PROC(p), td); 749} 750 751void 752sched_exit_thread(struct thread *td, struct thread *child) 753{ 754 755 KTR_STATE1(KTR_SCHED, "thread", sched_tdname(child), "exit", 756 "prio:%d", child->td_priority); 757 thread_lock(td); 758 td_get_sched(td)->ts_estcpu = ESTCPULIM(td_get_sched(td)->ts_estcpu + 759 td_get_sched(child)->ts_estcpu); 760 thread_unlock(td); 761 thread_lock(child); 762 if ((child->td_flags & TDF_NOLOAD) == 0) 763 sched_load_rem(); 764 thread_unlock(child); 765} 766 767void 768sched_fork(struct thread *td, struct thread *childtd) 769{ 770 sched_fork_thread(td, childtd); 771} 772 773void 774sched_fork_thread(struct thread *td, struct thread *childtd) 775{ 776 struct td_sched *ts, *tsc; 777 778 childtd->td_oncpu = NOCPU; 779 childtd->td_lastcpu = NOCPU; 780 childtd->td_lock = &sched_lock; 781 childtd->td_cpuset = cpuset_ref(td->td_cpuset); 782 childtd->td_priority = childtd->td_base_pri; 783 ts = td_get_sched(childtd); 784 bzero(ts, sizeof(*ts)); 785 tsc = td_get_sched(td); 786 ts->ts_estcpu = tsc->ts_estcpu; 787 ts->ts_flags |= (tsc->ts_flags & TSF_AFFINITY); 788 ts->ts_slice = 1; 789} 790 791void 792sched_nice(struct proc *p, int nice) 793{ 794 struct thread *td; 795 796 PROC_LOCK_ASSERT(p, MA_OWNED); 797 p->p_nice = nice; 798 FOREACH_THREAD_IN_PROC(p, td) { 799 thread_lock(td); 800 resetpriority(td); 801 resetpriority_thread(td); 802 thread_unlock(td); 803 } 804} 805 806void 807sched_class(struct thread *td, int class) 808{ 809 THREAD_LOCK_ASSERT(td, MA_OWNED); 810 td->td_pri_class = class; 811} 812 813/* 814 * Adjust the priority of a thread. 815 */ 816static void 817sched_priority(struct thread *td, u_char prio) 818{ 819 820 821 KTR_POINT3(KTR_SCHED, "thread", sched_tdname(td), "priority change", 822 "prio:%d", td->td_priority, "new prio:%d", prio, KTR_ATTR_LINKED, 823 sched_tdname(curthread)); 824 SDT_PROBE3(sched, , , change__pri, td, td->td_proc, prio); 825 if (td != curthread && prio > td->td_priority) { 826 KTR_POINT3(KTR_SCHED, "thread", sched_tdname(curthread), 827 "lend prio", "prio:%d", td->td_priority, "new prio:%d", 828 prio, KTR_ATTR_LINKED, sched_tdname(td)); 829 SDT_PROBE4(sched, , , lend__pri, td, td->td_proc, prio, 830 curthread); 831 } 832 THREAD_LOCK_ASSERT(td, MA_OWNED); 833 if (td->td_priority == prio) 834 return; 835 td->td_priority = prio; 836 if (TD_ON_RUNQ(td) && td->td_rqindex != (prio / RQ_PPQ)) { 837 sched_rem(td); 838 sched_add(td, SRQ_BORING); 839 } 840} 841 842/* 843 * Update a thread's priority when it is lent another thread's 844 * priority. 845 */ 846void 847sched_lend_prio(struct thread *td, u_char prio) 848{ 849 850 td->td_flags |= TDF_BORROWING; 851 sched_priority(td, prio); 852} 853 854/* 855 * Restore a thread's priority when priority propagation is 856 * over. The prio argument is the minimum priority the thread 857 * needs to have to satisfy other possible priority lending 858 * requests. If the thread's regulary priority is less 859 * important than prio the thread will keep a priority boost 860 * of prio. 861 */ 862void 863sched_unlend_prio(struct thread *td, u_char prio) 864{ 865 u_char base_pri; 866 867 if (td->td_base_pri >= PRI_MIN_TIMESHARE && 868 td->td_base_pri <= PRI_MAX_TIMESHARE) 869 base_pri = td->td_user_pri; 870 else 871 base_pri = td->td_base_pri; 872 if (prio >= base_pri) { 873 td->td_flags &= ~TDF_BORROWING; 874 sched_prio(td, base_pri); 875 } else 876 sched_lend_prio(td, prio); 877} 878 879void 880sched_prio(struct thread *td, u_char prio) 881{ 882 u_char oldprio; 883 884 /* First, update the base priority. */ 885 td->td_base_pri = prio; 886 887 /* 888 * If the thread is borrowing another thread's priority, don't ever 889 * lower the priority. 890 */ 891 if (td->td_flags & TDF_BORROWING && td->td_priority < prio) 892 return; 893 894 /* Change the real priority. */ 895 oldprio = td->td_priority; 896 sched_priority(td, prio); 897 898 /* 899 * If the thread is on a turnstile, then let the turnstile update 900 * its state. 901 */ 902 if (TD_ON_LOCK(td) && oldprio != prio) 903 turnstile_adjust(td, oldprio); 904} 905 906void 907sched_user_prio(struct thread *td, u_char prio) 908{ 909 910 THREAD_LOCK_ASSERT(td, MA_OWNED); 911 td->td_base_user_pri = prio; 912 if (td->td_lend_user_pri <= prio) 913 return; 914 td->td_user_pri = prio; 915} 916 917void 918sched_lend_user_prio(struct thread *td, u_char prio) 919{ 920 921 THREAD_LOCK_ASSERT(td, MA_OWNED); 922 td->td_lend_user_pri = prio; 923 td->td_user_pri = min(prio, td->td_base_user_pri); 924 if (td->td_priority > td->td_user_pri) 925 sched_prio(td, td->td_user_pri); 926 else if (td->td_priority != td->td_user_pri) 927 td->td_flags |= TDF_NEEDRESCHED; 928} 929 930void 931sched_sleep(struct thread *td, int pri) 932{ 933 934 THREAD_LOCK_ASSERT(td, MA_OWNED); 935 td->td_slptick = ticks; 936 td_get_sched(td)->ts_slptime = 0; 937 if (pri != 0 && PRI_BASE(td->td_pri_class) == PRI_TIMESHARE) 938 sched_prio(td, pri); 939 if (TD_IS_SUSPENDED(td) || pri >= PSOCK) 940 td->td_flags |= TDF_CANSWAP; 941} 942 943void 944sched_switch(struct thread *td, struct thread *newtd, int flags) 945{ 946 struct mtx *tmtx; 947 struct td_sched *ts; 948 struct proc *p; 949 int preempted; 950 951 tmtx = NULL; 952 ts = td_get_sched(td); 953 p = td->td_proc; 954 955 THREAD_LOCK_ASSERT(td, MA_OWNED); 956 957 /* 958 * Switch to the sched lock to fix things up and pick 959 * a new thread. 960 * Block the td_lock in order to avoid breaking the critical path. 961 */ 962 if (td->td_lock != &sched_lock) { 963 mtx_lock_spin(&sched_lock); 964 tmtx = thread_lock_block(td); 965 } 966 967 if ((td->td_flags & TDF_NOLOAD) == 0) 968 sched_load_rem(); 969 970 td->td_lastcpu = td->td_oncpu; 971 preempted = (td->td_flags & TDF_SLICEEND) == 0 && 972 (flags & SW_PREEMPT) != 0; 973 td->td_flags &= ~(TDF_NEEDRESCHED | TDF_SLICEEND); 974 td->td_owepreempt = 0; 975 td->td_oncpu = NOCPU; 976 977 /* 978 * At the last moment, if this thread is still marked RUNNING, 979 * then put it back on the run queue as it has not been suspended 980 * or stopped or any thing else similar. We never put the idle 981 * threads on the run queue, however. 982 */ 983 if (td->td_flags & TDF_IDLETD) { 984 TD_SET_CAN_RUN(td); 985#ifdef SMP 986 CPU_CLR(PCPU_GET(cpuid), &idle_cpus_mask); 987#endif 988 } else { 989 if (TD_IS_RUNNING(td)) { 990 /* Put us back on the run queue. */ 991 sched_add(td, preempted ? 992 SRQ_OURSELF|SRQ_YIELDING|SRQ_PREEMPTED : 993 SRQ_OURSELF|SRQ_YIELDING); 994 } 995 } 996 if (newtd) { 997 /* 998 * The thread we are about to run needs to be counted 999 * as if it had been added to the run queue and selected. 1000 * It came from: 1001 * * A preemption 1002 * * An upcall 1003 * * A followon 1004 */ 1005 KASSERT((newtd->td_inhibitors == 0), 1006 ("trying to run inhibited thread")); 1007 newtd->td_flags |= TDF_DIDRUN; 1008 TD_SET_RUNNING(newtd); 1009 if ((newtd->td_flags & TDF_NOLOAD) == 0) 1010 sched_load_add(); 1011 } else { 1012 newtd = choosethread(); 1013 MPASS(newtd->td_lock == &sched_lock); 1014 } 1015 1016#if (KTR_COMPILE & KTR_SCHED) != 0 1017 if (TD_IS_IDLETHREAD(td)) 1018 KTR_STATE1(KTR_SCHED, "thread", sched_tdname(td), "idle", 1019 "prio:%d", td->td_priority); 1020 else 1021 KTR_STATE3(KTR_SCHED, "thread", sched_tdname(td), KTDSTATE(td), 1022 "prio:%d", td->td_priority, "wmesg:\"%s\"", td->td_wmesg, 1023 "lockname:\"%s\"", td->td_lockname); 1024#endif 1025 1026 if (td != newtd) { 1027#ifdef HWPMC_HOOKS 1028 if (PMC_PROC_IS_USING_PMCS(td->td_proc)) 1029 PMC_SWITCH_CONTEXT(td, PMC_FN_CSW_OUT); 1030#endif 1031 1032 SDT_PROBE2(sched, , , off__cpu, newtd, newtd->td_proc); 1033 1034 /* I feel sleepy */ 1035 lock_profile_release_lock(&sched_lock.lock_object); 1036#ifdef KDTRACE_HOOKS 1037 /* 1038 * If DTrace has set the active vtime enum to anything 1039 * other than INACTIVE (0), then it should have set the 1040 * function to call. 1041 */ 1042 if (dtrace_vtime_active) 1043 (*dtrace_vtime_switch_func)(newtd); 1044#endif 1045 1046 cpu_switch(td, newtd, tmtx != NULL ? tmtx : td->td_lock); 1047 lock_profile_obtain_lock_success(&sched_lock.lock_object, 1048 0, 0, __FILE__, __LINE__); 1049 /* 1050 * Where am I? What year is it? 1051 * We are in the same thread that went to sleep above, 1052 * but any amount of time may have passed. All our context 1053 * will still be available as will local variables. 1054 * PCPU values however may have changed as we may have 1055 * changed CPU so don't trust cached values of them. 1056 * New threads will go to fork_exit() instead of here 1057 * so if you change things here you may need to change 1058 * things there too. 1059 * 1060 * If the thread above was exiting it will never wake 1061 * up again here, so either it has saved everything it 1062 * needed to, or the thread_wait() or wait() will 1063 * need to reap it. 1064 */ 1065 1066 SDT_PROBE0(sched, , , on__cpu); 1067#ifdef HWPMC_HOOKS 1068 if (PMC_PROC_IS_USING_PMCS(td->td_proc)) 1069 PMC_SWITCH_CONTEXT(td, PMC_FN_CSW_IN); 1070#endif 1071 } else 1072 SDT_PROBE0(sched, , , remain__cpu); 1073 1074 KTR_STATE1(KTR_SCHED, "thread", sched_tdname(td), "running", 1075 "prio:%d", td->td_priority); 1076 1077#ifdef SMP 1078 if (td->td_flags & TDF_IDLETD) 1079 CPU_SET(PCPU_GET(cpuid), &idle_cpus_mask); 1080#endif 1081 sched_lock.mtx_lock = (uintptr_t)td; 1082 td->td_oncpu = PCPU_GET(cpuid); 1083 MPASS(td->td_lock == &sched_lock); 1084} 1085 1086void 1087sched_wakeup(struct thread *td) 1088{ 1089 struct td_sched *ts; 1090 1091 THREAD_LOCK_ASSERT(td, MA_OWNED); 1092 ts = td_get_sched(td); 1093 td->td_flags &= ~TDF_CANSWAP; 1094 if (ts->ts_slptime > 1) { 1095 updatepri(td); 1096 resetpriority(td); 1097 } 1098 td->td_slptick = 0; 1099 ts->ts_slptime = 0; 1100 ts->ts_slice = sched_slice; 1101 sched_add(td, SRQ_BORING); 1102} 1103 1104#ifdef SMP 1105static int 1106forward_wakeup(int cpunum) 1107{ 1108 struct pcpu *pc; 1109 cpuset_t dontuse, map, map2; 1110 u_int id, me; 1111 int iscpuset; 1112 1113 mtx_assert(&sched_lock, MA_OWNED); 1114 1115 CTR0(KTR_RUNQ, "forward_wakeup()"); 1116 1117 if ((!forward_wakeup_enabled) || 1118 (forward_wakeup_use_mask == 0 && forward_wakeup_use_loop == 0)) 1119 return (0); 1120 if (!smp_started || panicstr) 1121 return (0); 1122 1123 forward_wakeups_requested++; 1124 1125 /* 1126 * Check the idle mask we received against what we calculated 1127 * before in the old version. 1128 */ 1129 me = PCPU_GET(cpuid); 1130 1131 /* Don't bother if we should be doing it ourself. */ 1132 if (CPU_ISSET(me, &idle_cpus_mask) && 1133 (cpunum == NOCPU || me == cpunum)) 1134 return (0); 1135 1136 CPU_SETOF(me, &dontuse); 1137 CPU_OR(&dontuse, &stopped_cpus); 1138 CPU_OR(&dontuse, &hlt_cpus_mask); 1139 CPU_ZERO(&map2); 1140 if (forward_wakeup_use_loop) { 1141 STAILQ_FOREACH(pc, &cpuhead, pc_allcpu) { 1142 id = pc->pc_cpuid; 1143 if (!CPU_ISSET(id, &dontuse) && 1144 pc->pc_curthread == pc->pc_idlethread) { 1145 CPU_SET(id, &map2); 1146 } 1147 } 1148 } 1149 1150 if (forward_wakeup_use_mask) { 1151 map = idle_cpus_mask; 1152 CPU_NAND(&map, &dontuse); 1153 1154 /* If they are both on, compare and use loop if different. */ 1155 if (forward_wakeup_use_loop) { 1156 if (CPU_CMP(&map, &map2)) { 1157 printf("map != map2, loop method preferred\n"); 1158 map = map2; 1159 } 1160 } 1161 } else { 1162 map = map2; 1163 } 1164 1165 /* If we only allow a specific CPU, then mask off all the others. */ 1166 if (cpunum != NOCPU) { 1167 KASSERT((cpunum <= mp_maxcpus),("forward_wakeup: bad cpunum.")); 1168 iscpuset = CPU_ISSET(cpunum, &map); 1169 if (iscpuset == 0) 1170 CPU_ZERO(&map); 1171 else 1172 CPU_SETOF(cpunum, &map); 1173 } 1174 if (!CPU_EMPTY(&map)) { 1175 forward_wakeups_delivered++; 1176 STAILQ_FOREACH(pc, &cpuhead, pc_allcpu) { 1177 id = pc->pc_cpuid; 1178 if (!CPU_ISSET(id, &map)) 1179 continue; 1180 if (cpu_idle_wakeup(pc->pc_cpuid)) 1181 CPU_CLR(id, &map); 1182 } 1183 if (!CPU_EMPTY(&map)) 1184 ipi_selected(map, IPI_AST); 1185 return (1); 1186 } 1187 if (cpunum == NOCPU) 1188 printf("forward_wakeup: Idle processor not found\n"); 1189 return (0); 1190} 1191 1192static void 1193kick_other_cpu(int pri, int cpuid) 1194{ 1195 struct pcpu *pcpu; 1196 int cpri; 1197 1198 pcpu = pcpu_find(cpuid); 1199 if (CPU_ISSET(cpuid, &idle_cpus_mask)) { 1200 forward_wakeups_delivered++; 1201 if (!cpu_idle_wakeup(cpuid)) 1202 ipi_cpu(cpuid, IPI_AST); 1203 return; 1204 } 1205 1206 cpri = pcpu->pc_curthread->td_priority; 1207 if (pri >= cpri) 1208 return; 1209 1210#if defined(IPI_PREEMPTION) && defined(PREEMPTION) 1211#if !defined(FULL_PREEMPTION) 1212 if (pri <= PRI_MAX_ITHD) 1213#endif /* ! FULL_PREEMPTION */ 1214 { 1215 ipi_cpu(cpuid, IPI_PREEMPT); 1216 return; 1217 } 1218#endif /* defined(IPI_PREEMPTION) && defined(PREEMPTION) */ 1219 1220 pcpu->pc_curthread->td_flags |= TDF_NEEDRESCHED; 1221 ipi_cpu(cpuid, IPI_AST); 1222 return; 1223} 1224#endif /* SMP */ 1225 1226#ifdef SMP 1227static int 1228sched_pickcpu(struct thread *td) 1229{ 1230 int best, cpu; 1231 1232 mtx_assert(&sched_lock, MA_OWNED); 1233 1234 if (td->td_lastcpu != NOCPU && THREAD_CAN_SCHED(td, td->td_lastcpu)) 1235 best = td->td_lastcpu; 1236 else 1237 best = NOCPU; 1238 CPU_FOREACH(cpu) { 1239 if (!THREAD_CAN_SCHED(td, cpu)) 1240 continue; 1241 1242 if (best == NOCPU) 1243 best = cpu; 1244 else if (runq_length[cpu] < runq_length[best]) 1245 best = cpu; 1246 } 1247 KASSERT(best != NOCPU, ("no valid CPUs")); 1248 1249 return (best); 1250} 1251#endif 1252 1253void 1254sched_add(struct thread *td, int flags) 1255#ifdef SMP 1256{ 1257 cpuset_t tidlemsk; 1258 struct td_sched *ts; 1259 u_int cpu, cpuid; 1260 int forwarded = 0; 1261 int single_cpu = 0; 1262 1263 ts = td_get_sched(td); 1264 THREAD_LOCK_ASSERT(td, MA_OWNED); 1265 KASSERT((td->td_inhibitors == 0), 1266 ("sched_add: trying to run inhibited thread")); 1267 KASSERT((TD_CAN_RUN(td) || TD_IS_RUNNING(td)), 1268 ("sched_add: bad thread state")); 1269 KASSERT(td->td_flags & TDF_INMEM, 1270 ("sched_add: thread swapped out")); 1271 1272 KTR_STATE2(KTR_SCHED, "thread", sched_tdname(td), "runq add", 1273 "prio:%d", td->td_priority, KTR_ATTR_LINKED, 1274 sched_tdname(curthread)); 1275 KTR_POINT1(KTR_SCHED, "thread", sched_tdname(curthread), "wokeup", 1276 KTR_ATTR_LINKED, sched_tdname(td)); 1277 SDT_PROBE4(sched, , , enqueue, td, td->td_proc, NULL, 1278 flags & SRQ_PREEMPTED); 1279 1280 1281 /* 1282 * Now that the thread is moving to the run-queue, set the lock 1283 * to the scheduler's lock. 1284 */ 1285 if (td->td_lock != &sched_lock) { 1286 mtx_lock_spin(&sched_lock); 1287 thread_lock_set(td, &sched_lock); 1288 } 1289 TD_SET_RUNQ(td); 1290 1291 /* 1292 * If SMP is started and the thread is pinned or otherwise limited to 1293 * a specific set of CPUs, queue the thread to a per-CPU run queue. 1294 * Otherwise, queue the thread to the global run queue. 1295 * 1296 * If SMP has not yet been started we must use the global run queue 1297 * as per-CPU state may not be initialized yet and we may crash if we 1298 * try to access the per-CPU run queues. 1299 */ 1300 if (smp_started && (td->td_pinned != 0 || td->td_flags & TDF_BOUND || 1301 ts->ts_flags & TSF_AFFINITY)) { 1302 if (td->td_pinned != 0) 1303 cpu = td->td_lastcpu; 1304 else if (td->td_flags & TDF_BOUND) { 1305 /* Find CPU from bound runq. */ 1306 KASSERT(SKE_RUNQ_PCPU(ts), 1307 ("sched_add: bound td_sched not on cpu runq")); 1308 cpu = ts->ts_runq - &runq_pcpu[0]; 1309 } else 1310 /* Find a valid CPU for our cpuset */ 1311 cpu = sched_pickcpu(td); 1312 ts->ts_runq = &runq_pcpu[cpu]; 1313 single_cpu = 1; 1314 CTR3(KTR_RUNQ, 1315 "sched_add: Put td_sched:%p(td:%p) on cpu%d runq", ts, td, 1316 cpu); 1317 } else { 1318 CTR2(KTR_RUNQ, 1319 "sched_add: adding td_sched:%p (td:%p) to gbl runq", ts, 1320 td); 1321 cpu = NOCPU; 1322 ts->ts_runq = &runq; 1323 } 1324 1325 if ((td->td_flags & TDF_NOLOAD) == 0) 1326 sched_load_add(); 1327 runq_add(ts->ts_runq, td, flags); 1328 if (cpu != NOCPU) 1329 runq_length[cpu]++; 1330 1331 cpuid = PCPU_GET(cpuid); 1332 if (single_cpu && cpu != cpuid) { 1333 kick_other_cpu(td->td_priority, cpu); 1334 } else { 1335 if (!single_cpu) { 1336 tidlemsk = idle_cpus_mask; 1337 CPU_NAND(&tidlemsk, &hlt_cpus_mask); 1338 CPU_CLR(cpuid, &tidlemsk); 1339 1340 if (!CPU_ISSET(cpuid, &idle_cpus_mask) && 1341 ((flags & SRQ_INTR) == 0) && 1342 !CPU_EMPTY(&tidlemsk)) 1343 forwarded = forward_wakeup(cpu); 1344 } 1345 1346 if (!forwarded) { 1347 if (!maybe_preempt(td)) 1348 maybe_resched(td); 1349 } 1350 } 1351} 1352#else /* SMP */ 1353{ 1354 struct td_sched *ts; 1355 1356 ts = td_get_sched(td); 1357 THREAD_LOCK_ASSERT(td, MA_OWNED); 1358 KASSERT((td->td_inhibitors == 0), 1359 ("sched_add: trying to run inhibited thread")); 1360 KASSERT((TD_CAN_RUN(td) || TD_IS_RUNNING(td)), 1361 ("sched_add: bad thread state")); 1362 KASSERT(td->td_flags & TDF_INMEM, 1363 ("sched_add: thread swapped out")); 1364 KTR_STATE2(KTR_SCHED, "thread", sched_tdname(td), "runq add", 1365 "prio:%d", td->td_priority, KTR_ATTR_LINKED, 1366 sched_tdname(curthread)); 1367 KTR_POINT1(KTR_SCHED, "thread", sched_tdname(curthread), "wokeup", 1368 KTR_ATTR_LINKED, sched_tdname(td)); 1369 SDT_PROBE4(sched, , , enqueue, td, td->td_proc, NULL, 1370 flags & SRQ_PREEMPTED); 1371 1372 /* 1373 * Now that the thread is moving to the run-queue, set the lock 1374 * to the scheduler's lock. 1375 */ 1376 if (td->td_lock != &sched_lock) { 1377 mtx_lock_spin(&sched_lock); 1378 thread_lock_set(td, &sched_lock); 1379 } 1380 TD_SET_RUNQ(td); 1381 CTR2(KTR_RUNQ, "sched_add: adding td_sched:%p (td:%p) to runq", ts, td); 1382 ts->ts_runq = &runq; 1383 1384 if ((td->td_flags & TDF_NOLOAD) == 0) 1385 sched_load_add(); 1386 runq_add(ts->ts_runq, td, flags); 1387 if (!maybe_preempt(td)) 1388 maybe_resched(td); 1389} 1390#endif /* SMP */ 1391 1392void 1393sched_rem(struct thread *td) 1394{ 1395 struct td_sched *ts; 1396 1397 ts = td_get_sched(td); 1398 KASSERT(td->td_flags & TDF_INMEM, 1399 ("sched_rem: thread swapped out")); 1400 KASSERT(TD_ON_RUNQ(td), 1401 ("sched_rem: thread not on run queue")); 1402 mtx_assert(&sched_lock, MA_OWNED); 1403 KTR_STATE2(KTR_SCHED, "thread", sched_tdname(td), "runq rem", 1404 "prio:%d", td->td_priority, KTR_ATTR_LINKED, 1405 sched_tdname(curthread)); 1406 SDT_PROBE3(sched, , , dequeue, td, td->td_proc, NULL); 1407 1408 if ((td->td_flags & TDF_NOLOAD) == 0) 1409 sched_load_rem(); 1410#ifdef SMP 1411 if (ts->ts_runq != &runq) 1412 runq_length[ts->ts_runq - runq_pcpu]--; 1413#endif 1414 runq_remove(ts->ts_runq, td); 1415 TD_SET_CAN_RUN(td); 1416} 1417 1418/* 1419 * Select threads to run. Note that running threads still consume a 1420 * slot. 1421 */ 1422struct thread * 1423sched_choose(void) 1424{ 1425 struct thread *td; 1426 struct runq *rq; 1427 1428 mtx_assert(&sched_lock, MA_OWNED); 1429#ifdef SMP 1430 struct thread *tdcpu; 1431 1432 rq = &runq; 1433 td = runq_choose_fuzz(&runq, runq_fuzz); 1434 tdcpu = runq_choose(&runq_pcpu[PCPU_GET(cpuid)]); 1435 1436 if (td == NULL || 1437 (tdcpu != NULL && 1438 tdcpu->td_priority < td->td_priority)) { 1439 CTR2(KTR_RUNQ, "choosing td %p from pcpu runq %d", tdcpu, 1440 PCPU_GET(cpuid)); 1441 td = tdcpu; 1442 rq = &runq_pcpu[PCPU_GET(cpuid)]; 1443 } else { 1444 CTR1(KTR_RUNQ, "choosing td_sched %p from main runq", td); 1445 } 1446 1447#else 1448 rq = &runq; 1449 td = runq_choose(&runq); 1450#endif 1451 1452 if (td) { 1453#ifdef SMP 1454 if (td == tdcpu) 1455 runq_length[PCPU_GET(cpuid)]--; 1456#endif 1457 runq_remove(rq, td); 1458 td->td_flags |= TDF_DIDRUN; 1459 1460 KASSERT(td->td_flags & TDF_INMEM, 1461 ("sched_choose: thread swapped out")); 1462 return (td); 1463 } 1464 return (PCPU_GET(idlethread)); 1465} 1466 1467void 1468sched_preempt(struct thread *td) 1469{ 1470 1471 SDT_PROBE2(sched, , , surrender, td, td->td_proc); 1472 thread_lock(td); 1473 if (td->td_critnest > 1) 1474 td->td_owepreempt = 1; 1475 else 1476 mi_switch(SW_INVOL | SW_PREEMPT | SWT_PREEMPT, NULL); 1477 thread_unlock(td); 1478} 1479 1480void 1481sched_userret(struct thread *td) 1482{ 1483 /* 1484 * XXX we cheat slightly on the locking here to avoid locking in 1485 * the usual case. Setting td_priority here is essentially an 1486 * incomplete workaround for not setting it properly elsewhere. 1487 * Now that some interrupt handlers are threads, not setting it 1488 * properly elsewhere can clobber it in the window between setting 1489 * it here and returning to user mode, so don't waste time setting 1490 * it perfectly here. 1491 */ 1492 KASSERT((td->td_flags & TDF_BORROWING) == 0, 1493 ("thread with borrowed priority returning to userland")); 1494 if (td->td_priority != td->td_user_pri) { 1495 thread_lock(td); 1496 td->td_priority = td->td_user_pri; 1497 td->td_base_pri = td->td_user_pri; 1498 thread_unlock(td); 1499 } 1500} 1501 1502void 1503sched_bind(struct thread *td, int cpu) 1504{ 1505 struct td_sched *ts; 1506 1507 THREAD_LOCK_ASSERT(td, MA_OWNED|MA_NOTRECURSED); 1508 KASSERT(td == curthread, ("sched_bind: can only bind curthread")); 1509 1510 ts = td_get_sched(td); 1511 1512 td->td_flags |= TDF_BOUND; 1513#ifdef SMP 1514 ts->ts_runq = &runq_pcpu[cpu]; 1515 if (PCPU_GET(cpuid) == cpu) 1516 return; 1517 1518 mi_switch(SW_VOL, NULL); 1519#endif 1520} 1521 1522void 1523sched_unbind(struct thread* td) 1524{ 1525 THREAD_LOCK_ASSERT(td, MA_OWNED); 1526 KASSERT(td == curthread, ("sched_unbind: can only bind curthread")); 1527 td->td_flags &= ~TDF_BOUND; 1528} 1529 1530int 1531sched_is_bound(struct thread *td) 1532{ 1533 THREAD_LOCK_ASSERT(td, MA_OWNED); 1534 return (td->td_flags & TDF_BOUND); 1535} 1536 1537void 1538sched_relinquish(struct thread *td) 1539{ 1540 thread_lock(td); 1541 mi_switch(SW_VOL | SWT_RELINQUISH, NULL); 1542 thread_unlock(td); 1543} 1544 1545int 1546sched_load(void) 1547{ 1548 return (sched_tdcnt); 1549} 1550 1551int 1552sched_sizeof_proc(void) 1553{ 1554 return (sizeof(struct proc)); 1555} 1556 1557int 1558sched_sizeof_thread(void) 1559{ 1560 return (sizeof(struct thread) + sizeof(struct td_sched)); 1561} 1562 1563fixpt_t 1564sched_pctcpu(struct thread *td) 1565{ 1566 struct td_sched *ts; 1567 1568 THREAD_LOCK_ASSERT(td, MA_OWNED); 1569 ts = td_get_sched(td); 1570 return (ts->ts_pctcpu); 1571} 1572 1573#ifdef RACCT 1574/* 1575 * Calculates the contribution to the thread cpu usage for the latest 1576 * (unfinished) second. 1577 */ 1578fixpt_t 1579sched_pctcpu_delta(struct thread *td) 1580{ 1581 struct td_sched *ts; 1582 fixpt_t delta; 1583 int realstathz; 1584 1585 THREAD_LOCK_ASSERT(td, MA_OWNED); 1586 ts = td_get_sched(td); 1587 delta = 0; 1588 realstathz = stathz ? stathz : hz; 1589 if (ts->ts_cpticks != 0) { 1590#if (FSHIFT >= CCPU_SHIFT) 1591 delta = (realstathz == 100) 1592 ? ((fixpt_t) ts->ts_cpticks) << 1593 (FSHIFT - CCPU_SHIFT) : 1594 100 * (((fixpt_t) ts->ts_cpticks) 1595 << (FSHIFT - CCPU_SHIFT)) / realstathz; 1596#else 1597 delta = ((FSCALE - ccpu) * 1598 (ts->ts_cpticks * 1599 FSCALE / realstathz)) >> FSHIFT; 1600#endif 1601 } 1602 1603 return (delta); 1604} 1605#endif 1606 1607u_int 1608sched_estcpu(struct thread *td) 1609{ 1610 1611 return (td_get_sched(td)->ts_estcpu); 1612} 1613 1614/* 1615 * The actual idle process. 1616 */ 1617void 1618sched_idletd(void *dummy) 1619{ 1620 struct pcpuidlestat *stat; 1621 1622 THREAD_NO_SLEEPING(); 1623 stat = DPCPU_PTR(idlestat); 1624 for (;;) { 1625 mtx_assert(&Giant, MA_NOTOWNED); 1626 1627 while (sched_runnable() == 0) { 1628 cpu_idle(stat->idlecalls + stat->oldidlecalls > 64); 1629 stat->idlecalls++; 1630 } 1631 1632 mtx_lock_spin(&sched_lock); 1633 mi_switch(SW_VOL | SWT_IDLE, NULL); 1634 mtx_unlock_spin(&sched_lock); 1635 } 1636} 1637 1638/* 1639 * A CPU is entering for the first time or a thread is exiting. 1640 */ 1641void 1642sched_throw(struct thread *td) 1643{ 1644 /* 1645 * Correct spinlock nesting. The idle thread context that we are 1646 * borrowing was created so that it would start out with a single 1647 * spin lock (sched_lock) held in fork_trampoline(). Since we've 1648 * explicitly acquired locks in this function, the nesting count 1649 * is now 2 rather than 1. Since we are nested, calling 1650 * spinlock_exit() will simply adjust the counts without allowing 1651 * spin lock using code to interrupt us. 1652 */ 1653 if (td == NULL) { 1654 mtx_lock_spin(&sched_lock); 1655 spinlock_exit(); 1656 PCPU_SET(switchtime, cpu_ticks()); 1657 PCPU_SET(switchticks, ticks); 1658 } else { 1659 lock_profile_release_lock(&sched_lock.lock_object); 1660 MPASS(td->td_lock == &sched_lock); 1661 td->td_lastcpu = td->td_oncpu; 1662 td->td_oncpu = NOCPU; 1663 } 1664 mtx_assert(&sched_lock, MA_OWNED); 1665 KASSERT(curthread->td_md.md_spinlock_count == 1, ("invalid count")); 1666 cpu_throw(td, choosethread()); /* doesn't return */ 1667} 1668 1669void 1670sched_fork_exit(struct thread *td) 1671{ 1672 1673 /* 1674 * Finish setting up thread glue so that it begins execution in a 1675 * non-nested critical section with sched_lock held but not recursed. 1676 */ 1677 td->td_oncpu = PCPU_GET(cpuid); 1678 sched_lock.mtx_lock = (uintptr_t)td; 1679 lock_profile_obtain_lock_success(&sched_lock.lock_object, 1680 0, 0, __FILE__, __LINE__); 1681 THREAD_LOCK_ASSERT(td, MA_OWNED | MA_NOTRECURSED); 1682 1683 KTR_STATE1(KTR_SCHED, "thread", sched_tdname(td), "running", 1684 "prio:%d", td->td_priority); 1685 SDT_PROBE0(sched, , , on__cpu); 1686} 1687 1688char * 1689sched_tdname(struct thread *td) 1690{ 1691#ifdef KTR 1692 struct td_sched *ts; 1693 1694 ts = td_get_sched(td); 1695 if (ts->ts_name[0] == '\0') 1696 snprintf(ts->ts_name, sizeof(ts->ts_name), 1697 "%s tid %d", td->td_name, td->td_tid); 1698 return (ts->ts_name); 1699#else 1700 return (td->td_name); 1701#endif 1702} 1703 1704#ifdef KTR 1705void 1706sched_clear_tdname(struct thread *td) 1707{ 1708 struct td_sched *ts; 1709 1710 ts = td_get_sched(td); 1711 ts->ts_name[0] = '\0'; 1712} 1713#endif 1714 1715void 1716sched_affinity(struct thread *td) 1717{ 1718#ifdef SMP 1719 struct td_sched *ts; 1720 int cpu; 1721 1722 THREAD_LOCK_ASSERT(td, MA_OWNED); 1723 1724 /* 1725 * Set the TSF_AFFINITY flag if there is at least one CPU this 1726 * thread can't run on. 1727 */ 1728 ts = td_get_sched(td); 1729 ts->ts_flags &= ~TSF_AFFINITY; 1730 CPU_FOREACH(cpu) { 1731 if (!THREAD_CAN_SCHED(td, cpu)) { 1732 ts->ts_flags |= TSF_AFFINITY; 1733 break; 1734 } 1735 } 1736 1737 /* 1738 * If this thread can run on all CPUs, nothing else to do. 1739 */ 1740 if (!(ts->ts_flags & TSF_AFFINITY)) 1741 return; 1742 1743 /* Pinned threads and bound threads should be left alone. */ 1744 if (td->td_pinned != 0 || td->td_flags & TDF_BOUND) 1745 return; 1746 1747 switch (td->td_state) { 1748 case TDS_RUNQ: 1749 /* 1750 * If we are on a per-CPU runqueue that is in the set, 1751 * then nothing needs to be done. 1752 */ 1753 if (ts->ts_runq != &runq && 1754 THREAD_CAN_SCHED(td, ts->ts_runq - runq_pcpu)) 1755 return; 1756 1757 /* Put this thread on a valid per-CPU runqueue. */ 1758 sched_rem(td); 1759 sched_add(td, SRQ_BORING); 1760 break; 1761 case TDS_RUNNING: 1762 /* 1763 * See if our current CPU is in the set. If not, force a 1764 * context switch. 1765 */ 1766 if (THREAD_CAN_SCHED(td, td->td_oncpu)) 1767 return; 1768 1769 td->td_flags |= TDF_NEEDRESCHED; 1770 if (td != curthread) 1771 ipi_cpu(cpu, IPI_AST); 1772 break; 1773 default: 1774 break; 1775 } 1776#endif 1777} 1778