Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)
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sys/kern/sched_4bsd.c
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1 /*- 2 * SPDX-License-Identifier: BSD-3-Clause 3 * 4 * Copyright (c) 1982, 1986, 1990, 1991, 1993 5 * The Regents of the University of California. All rights reserved. 6 * (c) UNIX System Laboratories, Inc. 7 * All or some portions of this file are derived from material licensed 8 * to the University of California by American Telephone and Telegraph 9 * Co. or Unix System Laboratories, Inc. and are reproduced herein with 10 * the permission of UNIX System Laboratories, Inc. 11 * 12 * Redistribution and use in source and binary forms, with or without 13 * modification, are permitted provided that the following conditions 14 * are met: 15 * 1. Redistributions of source code must retain the above copyright 16 * notice, this list of conditions and the following disclaimer. 17 * 2. Redistributions in binary form must reproduce the above copyright 18 * notice, this list of conditions and the following disclaimer in the 19 * documentation and/or other materials provided with the distribution. 20 * 3. Neither the name of the University nor the names of its contributors 21 * may be used to endorse or promote products derived from this software 22 * without specific prior written permission. 23 * 24 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 25 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 26 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 27 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 28 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 29 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 30 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 31 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 32 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 33 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 34 * SUCH DAMAGE. 35 */ 36 37 #include <sys/cdefs.h> 38 __FBSDID("$FreeBSD: releng/12.0/sys/kern/sched_4bsd.c 336007 2018-07-05 17:13:37Z andrew $"); 39 40 #include "opt_hwpmc_hooks.h" 41 #include "opt_sched.h" 42 43 #include <sys/param.h> 44 #include <sys/systm.h> 45 #include <sys/cpuset.h> 46 #include <sys/kernel.h> 47 #include <sys/ktr.h> 48 #include <sys/lock.h> 49 #include <sys/kthread.h> 50 #include <sys/mutex.h> 51 #include <sys/proc.h> 52 #include <sys/resourcevar.h> 53 #include <sys/sched.h> 54 #include <sys/sdt.h> 55 #include <sys/smp.h> 56 #include <sys/sysctl.h> 57 #include <sys/sx.h> 58 #include <sys/turnstile.h> 59 #include <sys/umtx.h> 60 #include <machine/pcb.h> 61 #include <machine/smp.h> 62 63 #ifdef HWPMC_HOOKS 64 #include <sys/pmckern.h> 65 #endif 66 67 #ifdef KDTRACE_HOOKS 68 #include <sys/dtrace_bsd.h> 69 int dtrace_vtime_active; 70 dtrace_vtime_switch_func_t dtrace_vtime_switch_func; 71 #endif 72 73 /* 74 * INVERSE_ESTCPU_WEIGHT is only suitable for statclock() frequencies in 75 * the range 100-256 Hz (approximately). 76 */ 77 #define ESTCPULIM(e) \ 78 min((e), INVERSE_ESTCPU_WEIGHT * (NICE_WEIGHT * (PRIO_MAX - PRIO_MIN) - \ 79 RQ_PPQ) + INVERSE_ESTCPU_WEIGHT - 1) 80 #ifdef SMP 81 #define INVERSE_ESTCPU_WEIGHT (8 * smp_cpus) 82 #else 83 #define INVERSE_ESTCPU_WEIGHT 8 /* 1 / (priorities per estcpu level). */ 84 #endif 85 #define NICE_WEIGHT 1 /* Priorities per nice level. */ 86 87 #define TS_NAME_LEN (MAXCOMLEN + sizeof(" td ") + sizeof(__XSTRING(UINT_MAX))) 88 89 /* 90 * The schedulable entity that runs a context. 91 * This is an extension to the thread structure and is tailored to 92 * the requirements of this scheduler. 93 * All fields are protected by the scheduler lock. 94 */ 95 struct td_sched { 96 fixpt_t ts_pctcpu; /* %cpu during p_swtime. */ 97 u_int ts_estcpu; /* Estimated cpu utilization. */ 98 int ts_cpticks; /* Ticks of cpu time. */ 99 int ts_slptime; /* Seconds !RUNNING. */ 100 int ts_slice; /* Remaining part of time slice. */ 101 int ts_flags; 102 struct runq *ts_runq; /* runq the thread is currently on */ 103 #ifdef KTR 104 char ts_name[TS_NAME_LEN]; 105 #endif 106 }; 107 108 /* flags kept in td_flags */ 109 #define TDF_DIDRUN TDF_SCHED0 /* thread actually ran. */ 110 #define TDF_BOUND TDF_SCHED1 /* Bound to one CPU. */ 111 #define TDF_SLICEEND TDF_SCHED2 /* Thread time slice is over. */ 112 113 /* flags kept in ts_flags */ 114 #define TSF_AFFINITY 0x0001 /* Has a non-"full" CPU set. */ 115 116 #define SKE_RUNQ_PCPU(ts) \ 117 ((ts)->ts_runq != 0 && (ts)->ts_runq != &runq) 118 119 #define THREAD_CAN_SCHED(td, cpu) \ 120 CPU_ISSET((cpu), &(td)->td_cpuset->cs_mask) 121 122 _Static_assert(sizeof(struct thread) + sizeof(struct td_sched) <= 123 sizeof(struct thread0_storage), 124 "increase struct thread0_storage.t0st_sched size"); 125 126 static struct mtx sched_lock; 127 128 static int realstathz = 127; /* stathz is sometimes 0 and run off of hz. */ 129 static int sched_tdcnt; /* Total runnable threads in the system. */ 130 static int sched_slice = 12; /* Thread run time before rescheduling. */ 131 132 static void setup_runqs(void); 133 static void schedcpu(void); 134 static void schedcpu_thread(void); 135 static void sched_priority(struct thread *td, u_char prio); 136 static void sched_setup(void *dummy); 137 static void maybe_resched(struct thread *td); 138 static void updatepri(struct thread *td); 139 static void resetpriority(struct thread *td); 140 static void resetpriority_thread(struct thread *td); 141 #ifdef SMP 142 static int sched_pickcpu(struct thread *td); 143 static int forward_wakeup(int cpunum); 144 static void kick_other_cpu(int pri, int cpuid); 145 #endif 146 147 static struct kproc_desc sched_kp = { 148 "schedcpu", 149 schedcpu_thread, 150 NULL 151 }; 152 SYSINIT(schedcpu, SI_SUB_LAST, SI_ORDER_FIRST, kproc_start, 153 &sched_kp); 154 SYSINIT(sched_setup, SI_SUB_RUN_QUEUE, SI_ORDER_FIRST, sched_setup, NULL); 155 156 static void sched_initticks(void *dummy); 157 SYSINIT(sched_initticks, SI_SUB_CLOCKS, SI_ORDER_THIRD, sched_initticks, 158 NULL); 159 160 /* 161 * Global run queue. 162 */ 163 static struct runq runq; 164 165 #ifdef SMP 166 /* 167 * Per-CPU run queues 168 */ 169 static struct runq runq_pcpu[MAXCPU]; 170 long runq_length[MAXCPU]; 171 172 static cpuset_t idle_cpus_mask; 173 #endif 174 175 struct pcpuidlestat { 176 u_int idlecalls; 177 u_int oldidlecalls; 178 }; 179 DPCPU_DEFINE_STATIC(struct pcpuidlestat, idlestat); 180 181 static void 182 setup_runqs(void) 183 { 184 #ifdef SMP 185 int i; 186 187 for (i = 0; i < MAXCPU; ++i) 188 runq_init(&runq_pcpu[i]); 189 #endif 190 191 runq_init(&runq); 192 } 193 194 static int 195 sysctl_kern_quantum(SYSCTL_HANDLER_ARGS) 196 { 197 int error, new_val, period; 198 199 period = 1000000 / realstathz; 200 new_val = period * sched_slice; 201 error = sysctl_handle_int(oidp, &new_val, 0, req); 202 if (error != 0 || req->newptr == NULL) 203 return (error); 204 if (new_val <= 0) 205 return (EINVAL); 206 sched_slice = imax(1, (new_val + period / 2) / period); 207 hogticks = imax(1, (2 * hz * sched_slice + realstathz / 2) / 208 realstathz); 209 return (0); 210 } 211 212 SYSCTL_NODE(_kern, OID_AUTO, sched, CTLFLAG_RD, 0, "Scheduler"); 213 214 SYSCTL_STRING(_kern_sched, OID_AUTO, name, CTLFLAG_RD, "4BSD", 0, 215 "Scheduler name"); 216 SYSCTL_PROC(_kern_sched, OID_AUTO, quantum, CTLTYPE_INT | CTLFLAG_RW, 217 NULL, 0, sysctl_kern_quantum, "I", 218 "Quantum for timeshare threads in microseconds"); 219 SYSCTL_INT(_kern_sched, OID_AUTO, slice, CTLFLAG_RW, &sched_slice, 0, 220 "Quantum for timeshare threads in stathz ticks"); 221 #ifdef SMP 222 /* Enable forwarding of wakeups to all other cpus */ 223 static SYSCTL_NODE(_kern_sched, OID_AUTO, ipiwakeup, CTLFLAG_RD, NULL, 224 "Kernel SMP"); 225 226 static int runq_fuzz = 1; 227 SYSCTL_INT(_kern_sched, OID_AUTO, runq_fuzz, CTLFLAG_RW, &runq_fuzz, 0, ""); 228 229 static int forward_wakeup_enabled = 1; 230 SYSCTL_INT(_kern_sched_ipiwakeup, OID_AUTO, enabled, CTLFLAG_RW, 231 &forward_wakeup_enabled, 0, 232 "Forwarding of wakeup to idle CPUs"); 233 234 static int forward_wakeups_requested = 0; 235 SYSCTL_INT(_kern_sched_ipiwakeup, OID_AUTO, requested, CTLFLAG_RD, 236 &forward_wakeups_requested, 0, 237 "Requests for Forwarding of wakeup to idle CPUs"); 238 239 static int forward_wakeups_delivered = 0; 240 SYSCTL_INT(_kern_sched_ipiwakeup, OID_AUTO, delivered, CTLFLAG_RD, 241 &forward_wakeups_delivered, 0, 242 "Completed Forwarding of wakeup to idle CPUs"); 243 244 static int forward_wakeup_use_mask = 1; 245 SYSCTL_INT(_kern_sched_ipiwakeup, OID_AUTO, usemask, CTLFLAG_RW, 246 &forward_wakeup_use_mask, 0, 247 "Use the mask of idle cpus"); 248 249 static int forward_wakeup_use_loop = 0; 250 SYSCTL_INT(_kern_sched_ipiwakeup, OID_AUTO, useloop, CTLFLAG_RW, 251 &forward_wakeup_use_loop, 0, 252 "Use a loop to find idle cpus"); 253 254 #endif 255 #if 0 256 static int sched_followon = 0; 257 SYSCTL_INT(_kern_sched, OID_AUTO, followon, CTLFLAG_RW, 258 &sched_followon, 0, 259 "allow threads to share a quantum"); 260 #endif 261 262 SDT_PROVIDER_DEFINE(sched); 263 264 SDT_PROBE_DEFINE3(sched, , , change__pri, "struct thread *", 265 "struct proc *", "uint8_t"); 266 SDT_PROBE_DEFINE3(sched, , , dequeue, "struct thread *", 267 "struct proc *", "void *"); 268 SDT_PROBE_DEFINE4(sched, , , enqueue, "struct thread *", 269 "struct proc *", "void *", "int"); 270 SDT_PROBE_DEFINE4(sched, , , lend__pri, "struct thread *", 271 "struct proc *", "uint8_t", "struct thread *"); 272 SDT_PROBE_DEFINE2(sched, , , load__change, "int", "int"); 273 SDT_PROBE_DEFINE2(sched, , , off__cpu, "struct thread *", 274 "struct proc *"); 275 SDT_PROBE_DEFINE(sched, , , on__cpu); 276 SDT_PROBE_DEFINE(sched, , , remain__cpu); 277 SDT_PROBE_DEFINE2(sched, , , surrender, "struct thread *", 278 "struct proc *"); 279 280 static __inline void 281 sched_load_add(void) 282 { 283 284 sched_tdcnt++; 285 KTR_COUNTER0(KTR_SCHED, "load", "global load", sched_tdcnt); 286 SDT_PROBE2(sched, , , load__change, NOCPU, sched_tdcnt); 287 } 288 289 static __inline void 290 sched_load_rem(void) 291 { 292 293 sched_tdcnt--; 294 KTR_COUNTER0(KTR_SCHED, "load", "global load", sched_tdcnt); 295 SDT_PROBE2(sched, , , load__change, NOCPU, sched_tdcnt); 296 } 297 /* 298 * Arrange to reschedule if necessary, taking the priorities and 299 * schedulers into account. 300 */ 301 static void 302 maybe_resched(struct thread *td) 303 { 304 305 THREAD_LOCK_ASSERT(td, MA_OWNED); 306 if (td->td_priority < curthread->td_priority) 307 curthread->td_flags |= TDF_NEEDRESCHED; 308 } 309 310 /* 311 * This function is called when a thread is about to be put on run queue 312 * because it has been made runnable or its priority has been adjusted. It 313 * determines if the new thread should preempt the current thread. If so, 314 * it sets td_owepreempt to request a preemption. 315 */ 316 int 317 maybe_preempt(struct thread *td) 318 { 319 #ifdef PREEMPTION 320 struct thread *ctd; 321 int cpri, pri; 322 323 /* 324 * The new thread should not preempt the current thread if any of the 325 * following conditions are true: 326 * 327 * - The kernel is in the throes of crashing (panicstr). 328 * - The current thread has a higher (numerically lower) or 329 * equivalent priority. Note that this prevents curthread from 330 * trying to preempt to itself. 331 * - The current thread has an inhibitor set or is in the process of 332 * exiting. In this case, the current thread is about to switch 333 * out anyways, so there's no point in preempting. If we did, 334 * the current thread would not be properly resumed as well, so 335 * just avoid that whole landmine. 336 * - If the new thread's priority is not a realtime priority and 337 * the current thread's priority is not an idle priority and 338 * FULL_PREEMPTION is disabled. 339 * 340 * If all of these conditions are false, but the current thread is in 341 * a nested critical section, then we have to defer the preemption 342 * until we exit the critical section. Otherwise, switch immediately 343 * to the new thread. 344 */ 345 ctd = curthread; 346 THREAD_LOCK_ASSERT(td, MA_OWNED); 347 KASSERT((td->td_inhibitors == 0), 348 ("maybe_preempt: trying to run inhibited thread")); 349 pri = td->td_priority; 350 cpri = ctd->td_priority; 351 if (panicstr != NULL || pri >= cpri /* || dumping */ || 352 TD_IS_INHIBITED(ctd)) 353 return (0); 354 #ifndef FULL_PREEMPTION 355 if (pri > PRI_MAX_ITHD && cpri < PRI_MIN_IDLE) 356 return (0); 357 #endif 358 359 CTR0(KTR_PROC, "maybe_preempt: scheduling preemption"); 360 ctd->td_owepreempt = 1; 361 return (1); 362 #else 363 return (0); 364 #endif 365 } 366 367 /* 368 * Constants for digital decay and forget: 369 * 90% of (ts_estcpu) usage in 5 * loadav time 370 * 95% of (ts_pctcpu) usage in 60 seconds (load insensitive) 371 * Note that, as ps(1) mentions, this can let percentages 372 * total over 100% (I've seen 137.9% for 3 processes). 373 * 374 * Note that schedclock() updates ts_estcpu and p_cpticks asynchronously. 375 * 376 * We wish to decay away 90% of ts_estcpu in (5 * loadavg) seconds. 377 * That is, the system wants to compute a value of decay such 378 * that the following for loop: 379 * for (i = 0; i < (5 * loadavg); i++) 380 * ts_estcpu *= decay; 381 * will compute 382 * ts_estcpu *= 0.1; 383 * for all values of loadavg: 384 * 385 * Mathematically this loop can be expressed by saying: 386 * decay ** (5 * loadavg) ~= .1 387 * 388 * The system computes decay as: 389 * decay = (2 * loadavg) / (2 * loadavg + 1) 390 * 391 * We wish to prove that the system's computation of decay 392 * will always fulfill the equation: 393 * decay ** (5 * loadavg) ~= .1 394 * 395 * If we compute b as: 396 * b = 2 * loadavg 397 * then 398 * decay = b / (b + 1) 399 * 400 * We now need to prove two things: 401 * 1) Given factor ** (5 * loadavg) ~= .1, prove factor == b/(b+1) 402 * 2) Given b/(b+1) ** power ~= .1, prove power == (5 * loadavg) 403 * 404 * Facts: 405 * For x close to zero, exp(x) =~ 1 + x, since 406 * exp(x) = 0! + x**1/1! + x**2/2! + ... . 407 * therefore exp(-1/b) =~ 1 - (1/b) = (b-1)/b. 408 * For x close to zero, ln(1+x) =~ x, since 409 * ln(1+x) = x - x**2/2 + x**3/3 - ... -1 < x < 1 410 * therefore ln(b/(b+1)) = ln(1 - 1/(b+1)) =~ -1/(b+1). 411 * ln(.1) =~ -2.30 412 * 413 * Proof of (1): 414 * Solve (factor)**(power) =~ .1 given power (5*loadav): 415 * solving for factor, 416 * ln(factor) =~ (-2.30/5*loadav), or 417 * factor =~ exp(-1/((5/2.30)*loadav)) =~ exp(-1/(2*loadav)) = 418 * exp(-1/b) =~ (b-1)/b =~ b/(b+1). QED 419 * 420 * Proof of (2): 421 * Solve (factor)**(power) =~ .1 given factor == (b/(b+1)): 422 * solving for power, 423 * power*ln(b/(b+1)) =~ -2.30, or 424 * power =~ 2.3 * (b + 1) = 4.6*loadav + 2.3 =~ 5*loadav. QED 425 * 426 * Actual power values for the implemented algorithm are as follows: 427 * loadav: 1 2 3 4 428 * power: 5.68 10.32 14.94 19.55 429 */ 430 431 /* calculations for digital decay to forget 90% of usage in 5*loadav sec */ 432 #define loadfactor(loadav) (2 * (loadav)) 433 #define decay_cpu(loadfac, cpu) (((loadfac) * (cpu)) / ((loadfac) + FSCALE)) 434 435 /* decay 95% of `ts_pctcpu' in 60 seconds; see CCPU_SHIFT before changing */ 436 static fixpt_t ccpu = 0.95122942450071400909 * FSCALE; /* exp(-1/20) */ 437 SYSCTL_UINT(_kern, OID_AUTO, ccpu, CTLFLAG_RD, &ccpu, 0, ""); 438 439 /* 440 * If `ccpu' is not equal to `exp(-1/20)' and you still want to use the 441 * faster/more-accurate formula, you'll have to estimate CCPU_SHIFT below 442 * and possibly adjust FSHIFT in "param.h" so that (FSHIFT >= CCPU_SHIFT). 443 * 444 * To estimate CCPU_SHIFT for exp(-1/20), the following formula was used: 445 * 1 - exp(-1/20) ~= 0.0487 ~= 0.0488 == 1 (fixed pt, *11* bits). 446 * 447 * If you don't want to bother with the faster/more-accurate formula, you 448 * can set CCPU_SHIFT to (FSHIFT + 1) which will use a slower/less-accurate 449 * (more general) method of calculating the %age of CPU used by a process. 450 */ 451 #define CCPU_SHIFT 11 452 453 /* 454 * Recompute process priorities, every hz ticks. 455 * MP-safe, called without the Giant mutex. 456 */ 457 /* ARGSUSED */ 458 static void 459 schedcpu(void) 460 { 461 fixpt_t loadfac = loadfactor(averunnable.ldavg[0]); 462 struct thread *td; 463 struct proc *p; 464 struct td_sched *ts; 465 int awake; 466 467 sx_slock(&allproc_lock); 468 FOREACH_PROC_IN_SYSTEM(p) { 469 PROC_LOCK(p); 470 if (p->p_state == PRS_NEW) { 471 PROC_UNLOCK(p); 472 continue; 473 } 474 FOREACH_THREAD_IN_PROC(p, td) { 475 awake = 0; 476 ts = td_get_sched(td); 477 thread_lock(td); 478 /* 479 * Increment sleep time (if sleeping). We 480 * ignore overflow, as above. 481 */ 482 /* 483 * The td_sched slptimes are not touched in wakeup 484 * because the thread may not HAVE everything in 485 * memory? XXX I think this is out of date. 486 */ 487 if (TD_ON_RUNQ(td)) { 488 awake = 1; 489 td->td_flags &= ~TDF_DIDRUN; 490 } else if (TD_IS_RUNNING(td)) { 491 awake = 1; 492 /* Do not clear TDF_DIDRUN */ 493 } else if (td->td_flags & TDF_DIDRUN) { 494 awake = 1; 495 td->td_flags &= ~TDF_DIDRUN; 496 } 497 498 /* 499 * ts_pctcpu is only for ps and ttyinfo(). 500 */ 501 ts->ts_pctcpu = (ts->ts_pctcpu * ccpu) >> FSHIFT; 502 /* 503 * If the td_sched has been idle the entire second, 504 * stop recalculating its priority until 505 * it wakes up. 506 */ 507 if (ts->ts_cpticks != 0) { 508 #if (FSHIFT >= CCPU_SHIFT) 509 ts->ts_pctcpu += (realstathz == 100) 510 ? ((fixpt_t) ts->ts_cpticks) << 511 (FSHIFT - CCPU_SHIFT) : 512 100 * (((fixpt_t) ts->ts_cpticks) 513 << (FSHIFT - CCPU_SHIFT)) / realstathz; 514 #else 515 ts->ts_pctcpu += ((FSCALE - ccpu) * 516 (ts->ts_cpticks * 517 FSCALE / realstathz)) >> FSHIFT; 518 #endif 519 ts->ts_cpticks = 0; 520 } 521 /* 522 * If there are ANY running threads in this process, 523 * then don't count it as sleeping. 524 * XXX: this is broken. 525 */ 526 if (awake) { 527 if (ts->ts_slptime > 1) { 528 /* 529 * In an ideal world, this should not 530 * happen, because whoever woke us 531 * up from the long sleep should have 532 * unwound the slptime and reset our 533 * priority before we run at the stale 534 * priority. Should KASSERT at some 535 * point when all the cases are fixed. 536 */ 537 updatepri(td); 538 } 539 ts->ts_slptime = 0; 540 } else 541 ts->ts_slptime++; 542 if (ts->ts_slptime > 1) { 543 thread_unlock(td); 544 continue; 545 } 546 ts->ts_estcpu = decay_cpu(loadfac, ts->ts_estcpu); 547 resetpriority(td); 548 resetpriority_thread(td); 549 thread_unlock(td); 550 } 551 PROC_UNLOCK(p); 552 } 553 sx_sunlock(&allproc_lock); 554 } 555 556 /* 557 * Main loop for a kthread that executes schedcpu once a second. 558 */ 559 static void 560 schedcpu_thread(void) 561 { 562 563 for (;;) { 564 schedcpu(); 565 pause("-", hz); 566 } 567 } 568 569 /* 570 * Recalculate the priority of a process after it has slept for a while. 571 * For all load averages >= 1 and max ts_estcpu of 255, sleeping for at 572 * least six times the loadfactor will decay ts_estcpu to zero. 573 */ 574 static void 575 updatepri(struct thread *td) 576 { 577 struct td_sched *ts; 578 fixpt_t loadfac; 579 unsigned int newcpu; 580 581 ts = td_get_sched(td); 582 loadfac = loadfactor(averunnable.ldavg[0]); 583 if (ts->ts_slptime > 5 * loadfac) 584 ts->ts_estcpu = 0; 585 else { 586 newcpu = ts->ts_estcpu; 587 ts->ts_slptime--; /* was incremented in schedcpu() */ 588 while (newcpu && --ts->ts_slptime) 589 newcpu = decay_cpu(loadfac, newcpu); 590 ts->ts_estcpu = newcpu; 591 } 592 } 593 594 /* 595 * Compute the priority of a process when running in user mode. 596 * Arrange to reschedule if the resulting priority is better 597 * than that of the current process. 598 */ 599 static void 600 resetpriority(struct thread *td) 601 { 602 u_int newpriority; 603 604 if (td->td_pri_class != PRI_TIMESHARE) 605 return; 606 newpriority = PUSER + 607 td_get_sched(td)->ts_estcpu / INVERSE_ESTCPU_WEIGHT + 608 NICE_WEIGHT * (td->td_proc->p_nice - PRIO_MIN); 609 newpriority = min(max(newpriority, PRI_MIN_TIMESHARE), 610 PRI_MAX_TIMESHARE); 611 sched_user_prio(td, newpriority); 612 } 613 614 /* 615 * Update the thread's priority when the associated process's user 616 * priority changes. 617 */ 618 static void 619 resetpriority_thread(struct thread *td) 620 { 621 622 /* Only change threads with a time sharing user priority. */ 623 if (td->td_priority < PRI_MIN_TIMESHARE || 624 td->td_priority > PRI_MAX_TIMESHARE) 625 return; 626 627 /* XXX the whole needresched thing is broken, but not silly. */ 628 maybe_resched(td); 629 630 sched_prio(td, td->td_user_pri); 631 } 632 633 /* ARGSUSED */ 634 static void 635 sched_setup(void *dummy) 636 { 637 638 setup_runqs(); 639 640 /* Account for thread0. */ 641 sched_load_add(); 642 } 643 644 /* 645 * This routine determines time constants after stathz and hz are setup. 646 */ 647 static void 648 sched_initticks(void *dummy) 649 { 650 651 realstathz = stathz ? stathz : hz; 652 sched_slice = realstathz / 10; /* ~100ms */ 653 hogticks = imax(1, (2 * hz * sched_slice + realstathz / 2) / 654 realstathz); 655 } 656 657 /* External interfaces start here */ 658 659 /* 660 * Very early in the boot some setup of scheduler-specific 661 * parts of proc0 and of some scheduler resources needs to be done. 662 * Called from: 663 * proc0_init() 664 */ 665 void 666 schedinit(void) 667 { 668 669 /* 670 * Set up the scheduler specific parts of thread0. 671 */ 672 thread0.td_lock = &sched_lock; 673 td_get_sched(&thread0)->ts_slice = sched_slice; 674 mtx_init(&sched_lock, "sched lock", NULL, MTX_SPIN | MTX_RECURSE); 675 } 676 677 int 678 sched_runnable(void) 679 { 680 #ifdef SMP 681 return runq_check(&runq) + runq_check(&runq_pcpu[PCPU_GET(cpuid)]); 682 #else 683 return runq_check(&runq); 684 #endif 685 } 686 687 int 688 sched_rr_interval(void) 689 { 690 691 /* Convert sched_slice from stathz to hz. */ 692 return (imax(1, (sched_slice * hz + realstathz / 2) / realstathz)); 693 } 694 695 /* 696 * We adjust the priority of the current process. The priority of a 697 * process gets worse as it accumulates CPU time. The cpu usage 698 * estimator (ts_estcpu) is increased here. resetpriority() will 699 * compute a different priority each time ts_estcpu increases by 700 * INVERSE_ESTCPU_WEIGHT (until PRI_MAX_TIMESHARE is reached). The 701 * cpu usage estimator ramps up quite quickly when the process is 702 * running (linearly), and decays away exponentially, at a rate which 703 * is proportionally slower when the system is busy. The basic 704 * principle is that the system will 90% forget that the process used 705 * a lot of CPU time in 5 * loadav seconds. This causes the system to 706 * favor processes which haven't run much recently, and to round-robin 707 * among other processes. 708 */ 709 void 710 sched_clock(struct thread *td) 711 { 712 struct pcpuidlestat *stat; 713 struct td_sched *ts; 714 715 THREAD_LOCK_ASSERT(td, MA_OWNED); 716 ts = td_get_sched(td); 717 718 ts->ts_cpticks++; 719 ts->ts_estcpu = ESTCPULIM(ts->ts_estcpu + 1); 720 if ((ts->ts_estcpu % INVERSE_ESTCPU_WEIGHT) == 0) { 721 resetpriority(td); 722 resetpriority_thread(td); 723 } 724 725 /* 726 * Force a context switch if the current thread has used up a full 727 * time slice (default is 100ms). 728 */ 729 if (!TD_IS_IDLETHREAD(td) && --ts->ts_slice <= 0) { 730 ts->ts_slice = sched_slice; 731 td->td_flags |= TDF_NEEDRESCHED | TDF_SLICEEND; 732 } 733 734 stat = DPCPU_PTR(idlestat); 735 stat->oldidlecalls = stat->idlecalls; 736 stat->idlecalls = 0; 737 } 738 739 /* 740 * Charge child's scheduling CPU usage to parent. 741 */ 742 void 743 sched_exit(struct proc *p, struct thread *td) 744 { 745 746 KTR_STATE1(KTR_SCHED, "thread", sched_tdname(td), "proc exit", 747 "prio:%d", td->td_priority); 748 749 PROC_LOCK_ASSERT(p, MA_OWNED); 750 sched_exit_thread(FIRST_THREAD_IN_PROC(p), td); 751 } 752 753 void 754 sched_exit_thread(struct thread *td, struct thread *child) 755 { 756 757 KTR_STATE1(KTR_SCHED, "thread", sched_tdname(child), "exit", 758 "prio:%d", child->td_priority); 759 thread_lock(td); 760 td_get_sched(td)->ts_estcpu = ESTCPULIM(td_get_sched(td)->ts_estcpu + 761 td_get_sched(child)->ts_estcpu); 762 thread_unlock(td); 763 thread_lock(child); 764 if ((child->td_flags & TDF_NOLOAD) == 0) 765 sched_load_rem(); 766 thread_unlock(child); 767 } 768 769 void 770 sched_fork(struct thread *td, struct thread *childtd) 771 { 772 sched_fork_thread(td, childtd); 773 } 774 775 void 776 sched_fork_thread(struct thread *td, struct thread *childtd) 777 { 778 struct td_sched *ts, *tsc; 779 780 childtd->td_oncpu = NOCPU; 781 childtd->td_lastcpu = NOCPU; 782 childtd->td_lock = &sched_lock; 783 childtd->td_cpuset = cpuset_ref(td->td_cpuset); 784 childtd->td_domain.dr_policy = td->td_cpuset->cs_domain; 785 childtd->td_priority = childtd->td_base_pri; 786 ts = td_get_sched(childtd); 787 bzero(ts, sizeof(*ts)); 788 tsc = td_get_sched(td); 789 ts->ts_estcpu = tsc->ts_estcpu; 790 ts->ts_flags |= (tsc->ts_flags & TSF_AFFINITY); 791 ts->ts_slice = 1; 792 } 793 794 void 795 sched_nice(struct proc *p, int nice) 796 { 797 struct thread *td; 798 799 PROC_LOCK_ASSERT(p, MA_OWNED); 800 p->p_nice = nice; 801 FOREACH_THREAD_IN_PROC(p, td) { 802 thread_lock(td); 803 resetpriority(td); 804 resetpriority_thread(td); 805 thread_unlock(td); 806 } 807 } 808 809 void 810 sched_class(struct thread *td, int class) 811 { 812 THREAD_LOCK_ASSERT(td, MA_OWNED); 813 td->td_pri_class = class; 814 } 815 816 /* 817 * Adjust the priority of a thread. 818 */ 819 static void 820 sched_priority(struct thread *td, u_char prio) 821 { 822 823 824 KTR_POINT3(KTR_SCHED, "thread", sched_tdname(td), "priority change", 825 "prio:%d", td->td_priority, "new prio:%d", prio, KTR_ATTR_LINKED, 826 sched_tdname(curthread)); 827 SDT_PROBE3(sched, , , change__pri, td, td->td_proc, prio); 828 if (td != curthread && prio > td->td_priority) { 829 KTR_POINT3(KTR_SCHED, "thread", sched_tdname(curthread), 830 "lend prio", "prio:%d", td->td_priority, "new prio:%d", 831 prio, KTR_ATTR_LINKED, sched_tdname(td)); 832 SDT_PROBE4(sched, , , lend__pri, td, td->td_proc, prio, 833 curthread); 834 } 835 THREAD_LOCK_ASSERT(td, MA_OWNED); 836 if (td->td_priority == prio) 837 return; 838 td->td_priority = prio; 839 if (TD_ON_RUNQ(td) && td->td_rqindex != (prio / RQ_PPQ)) { 840 sched_rem(td); 841 sched_add(td, SRQ_BORING); 842 } 843 } 844 845 /* 846 * Update a thread's priority when it is lent another thread's 847 * priority. 848 */ 849 void 850 sched_lend_prio(struct thread *td, u_char prio) 851 { 852 853 td->td_flags |= TDF_BORROWING; 854 sched_priority(td, prio); 855 } 856 857 /* 858 * Restore a thread's priority when priority propagation is 859 * over. The prio argument is the minimum priority the thread 860 * needs to have to satisfy other possible priority lending 861 * requests. If the thread's regulary priority is less 862 * important than prio the thread will keep a priority boost 863 * of prio. 864 */ 865 void 866 sched_unlend_prio(struct thread *td, u_char prio) 867 { 868 u_char base_pri; 869 870 if (td->td_base_pri >= PRI_MIN_TIMESHARE && 871 td->td_base_pri <= PRI_MAX_TIMESHARE) 872 base_pri = td->td_user_pri; 873 else 874 base_pri = td->td_base_pri; 875 if (prio >= base_pri) { 876 td->td_flags &= ~TDF_BORROWING; 877 sched_prio(td, base_pri); 878 } else 879 sched_lend_prio(td, prio); 880 } 881 882 void 883 sched_prio(struct thread *td, u_char prio) 884 { 885 u_char oldprio; 886 887 /* First, update the base priority. */ 888 td->td_base_pri = prio; 889 890 /* 891 * If the thread is borrowing another thread's priority, don't ever 892 * lower the priority. 893 */ 894 if (td->td_flags & TDF_BORROWING && td->td_priority < prio) 895 return; 896 897 /* Change the real priority. */ 898 oldprio = td->td_priority; 899 sched_priority(td, prio); 900 901 /* 902 * If the thread is on a turnstile, then let the turnstile update 903 * its state. 904 */ 905 if (TD_ON_LOCK(td) && oldprio != prio) 906 turnstile_adjust(td, oldprio); 907 } 908 909 void 910 sched_user_prio(struct thread *td, u_char prio) 911 { 912 913 THREAD_LOCK_ASSERT(td, MA_OWNED); 914 td->td_base_user_pri = prio; 915 if (td->td_lend_user_pri <= prio) 916 return; 917 td->td_user_pri = prio; 918 } 919 920 void 921 sched_lend_user_prio(struct thread *td, u_char prio) 922 { 923 924 THREAD_LOCK_ASSERT(td, MA_OWNED); 925 td->td_lend_user_pri = prio; 926 td->td_user_pri = min(prio, td->td_base_user_pri); 927 if (td->td_priority > td->td_user_pri) 928 sched_prio(td, td->td_user_pri); 929 else if (td->td_priority != td->td_user_pri) 930 td->td_flags |= TDF_NEEDRESCHED; 931 } 932 933 void 934 sched_sleep(struct thread *td, int pri) 935 { 936 937 THREAD_LOCK_ASSERT(td, MA_OWNED); 938 td->td_slptick = ticks; 939 td_get_sched(td)->ts_slptime = 0; 940 if (pri != 0 && PRI_BASE(td->td_pri_class) == PRI_TIMESHARE) 941 sched_prio(td, pri); 942 if (TD_IS_SUSPENDED(td) || pri >= PSOCK) 943 td->td_flags |= TDF_CANSWAP; 944 } 945 946 void 947 sched_switch(struct thread *td, struct thread *newtd, int flags) 948 { 949 struct mtx *tmtx; 950 struct td_sched *ts; 951 struct proc *p; 952 int preempted; 953 954 tmtx = NULL; 955 ts = td_get_sched(td); 956 p = td->td_proc; 957 958 THREAD_LOCK_ASSERT(td, MA_OWNED); 959 960 /* 961 * Switch to the sched lock to fix things up and pick 962 * a new thread. 963 * Block the td_lock in order to avoid breaking the critical path. 964 */ 965 if (td->td_lock != &sched_lock) { 966 mtx_lock_spin(&sched_lock); 967 tmtx = thread_lock_block(td); 968 } 969 970 if ((td->td_flags & TDF_NOLOAD) == 0) 971 sched_load_rem(); 972 973 td->td_lastcpu = td->td_oncpu; 974 preempted = (td->td_flags & TDF_SLICEEND) == 0 && 975 (flags & SW_PREEMPT) != 0; 976 td->td_flags &= ~(TDF_NEEDRESCHED | TDF_SLICEEND); 977 td->td_owepreempt = 0; 978 td->td_oncpu = NOCPU; 979 980 /* 981 * At the last moment, if this thread is still marked RUNNING, 982 * then put it back on the run queue as it has not been suspended 983 * or stopped or any thing else similar. We never put the idle 984 * threads on the run queue, however. 985 */ 986 if (td->td_flags & TDF_IDLETD) { 987 TD_SET_CAN_RUN(td); 988 #ifdef SMP 989 CPU_CLR(PCPU_GET(cpuid), &idle_cpus_mask); 990 #endif 991 } else { 992 if (TD_IS_RUNNING(td)) { 993 /* Put us back on the run queue. */ 994 sched_add(td, preempted ? 995 SRQ_OURSELF|SRQ_YIELDING|SRQ_PREEMPTED : 996 SRQ_OURSELF|SRQ_YIELDING); 997 } 998 } 999 if (newtd) { 1000 /* 1001 * The thread we are about to run needs to be counted 1002 * as if it had been added to the run queue and selected. 1003 * It came from: 1004 * * A preemption 1005 * * An upcall 1006 * * A followon 1007 */ 1008 KASSERT((newtd->td_inhibitors == 0), 1009 ("trying to run inhibited thread")); 1010 newtd->td_flags |= TDF_DIDRUN; 1011 TD_SET_RUNNING(newtd); 1012 if ((newtd->td_flags & TDF_NOLOAD) == 0) 1013 sched_load_add(); 1014 } else { 1015 newtd = choosethread(); 1016 MPASS(newtd->td_lock == &sched_lock); 1017 } 1018 1019 #if (KTR_COMPILE & KTR_SCHED) != 0 1020 if (TD_IS_IDLETHREAD(td)) 1021 KTR_STATE1(KTR_SCHED, "thread", sched_tdname(td), "idle", 1022 "prio:%d", td->td_priority); 1023 else 1024 KTR_STATE3(KTR_SCHED, "thread", sched_tdname(td), KTDSTATE(td), 1025 "prio:%d", td->td_priority, "wmesg:\"%s\"", td->td_wmesg, 1026 "lockname:\"%s\"", td->td_lockname); 1027 #endif 1028 1029 if (td != newtd) { 1030 #ifdef HWPMC_HOOKS 1031 if (PMC_PROC_IS_USING_PMCS(td->td_proc)) 1032 PMC_SWITCH_CONTEXT(td, PMC_FN_CSW_OUT); 1033 #endif 1034 1035 SDT_PROBE2(sched, , , off__cpu, newtd, newtd->td_proc); 1036 1037 /* I feel sleepy */ 1038 lock_profile_release_lock(&sched_lock.lock_object); 1039 #ifdef KDTRACE_HOOKS 1040 /* 1041 * If DTrace has set the active vtime enum to anything 1042 * other than INACTIVE (0), then it should have set the 1043 * function to call. 1044 */ 1045 if (dtrace_vtime_active) 1046 (*dtrace_vtime_switch_func)(newtd); 1047 #endif 1048 1049 cpu_switch(td, newtd, tmtx != NULL ? tmtx : td->td_lock); 1050 lock_profile_obtain_lock_success(&sched_lock.lock_object, 1051 0, 0, __FILE__, __LINE__); 1052 /* 1053 * Where am I? What year is it? 1054 * We are in the same thread that went to sleep above, 1055 * but any amount of time may have passed. All our context 1056 * will still be available as will local variables. 1057 * PCPU values however may have changed as we may have 1058 * changed CPU so don't trust cached values of them. 1059 * New threads will go to fork_exit() instead of here 1060 * so if you change things here you may need to change 1061 * things there too. 1062 * 1063 * If the thread above was exiting it will never wake 1064 * up again here, so either it has saved everything it 1065 * needed to, or the thread_wait() or wait() will 1066 * need to reap it. 1067 */ 1068 1069 SDT_PROBE0(sched, , , on__cpu); 1070 #ifdef HWPMC_HOOKS 1071 if (PMC_PROC_IS_USING_PMCS(td->td_proc)) 1072 PMC_SWITCH_CONTEXT(td, PMC_FN_CSW_IN); 1073 #endif 1074 } else 1075 SDT_PROBE0(sched, , , remain__cpu); 1076 1077 KTR_STATE1(KTR_SCHED, "thread", sched_tdname(td), "running", 1078 "prio:%d", td->td_priority); 1079 1080 #ifdef SMP 1081 if (td->td_flags & TDF_IDLETD) 1082 CPU_SET(PCPU_GET(cpuid), &idle_cpus_mask); 1083 #endif 1084 sched_lock.mtx_lock = (uintptr_t)td; 1085 td->td_oncpu = PCPU_GET(cpuid); 1086 MPASS(td->td_lock == &sched_lock); 1087 } 1088 1089 void 1090 sched_wakeup(struct thread *td) 1091 { 1092 struct td_sched *ts; 1093 1094 THREAD_LOCK_ASSERT(td, MA_OWNED); 1095 ts = td_get_sched(td); 1096 td->td_flags &= ~TDF_CANSWAP; 1097 if (ts->ts_slptime > 1) { 1098 updatepri(td); 1099 resetpriority(td); 1100 } 1101 td->td_slptick = 0; 1102 ts->ts_slptime = 0; 1103 ts->ts_slice = sched_slice; 1104 sched_add(td, SRQ_BORING); 1105 } 1106 1107 #ifdef SMP 1108 static int 1109 forward_wakeup(int cpunum) 1110 { 1111 struct pcpu *pc; 1112 cpuset_t dontuse, map, map2; 1113 u_int id, me; 1114 int iscpuset; 1115 1116 mtx_assert(&sched_lock, MA_OWNED); 1117 1118 CTR0(KTR_RUNQ, "forward_wakeup()"); 1119 1120 if ((!forward_wakeup_enabled) || 1121 (forward_wakeup_use_mask == 0 && forward_wakeup_use_loop == 0)) 1122 return (0); 1123 if (!smp_started || panicstr) 1124 return (0); 1125 1126 forward_wakeups_requested++; 1127 1128 /* 1129 * Check the idle mask we received against what we calculated 1130 * before in the old version. 1131 */ 1132 me = PCPU_GET(cpuid); 1133 1134 /* Don't bother if we should be doing it ourself. */ 1135 if (CPU_ISSET(me, &idle_cpus_mask) && 1136 (cpunum == NOCPU || me == cpunum)) 1137 return (0); 1138 1139 CPU_SETOF(me, &dontuse); 1140 CPU_OR(&dontuse, &stopped_cpus); 1141 CPU_OR(&dontuse, &hlt_cpus_mask); 1142 CPU_ZERO(&map2); 1143 if (forward_wakeup_use_loop) { 1144 STAILQ_FOREACH(pc, &cpuhead, pc_allcpu) { 1145 id = pc->pc_cpuid; 1146 if (!CPU_ISSET(id, &dontuse) && 1147 pc->pc_curthread == pc->pc_idlethread) { 1148 CPU_SET(id, &map2); 1149 } 1150 } 1151 } 1152 1153 if (forward_wakeup_use_mask) { 1154 map = idle_cpus_mask; 1155 CPU_NAND(&map, &dontuse); 1156 1157 /* If they are both on, compare and use loop if different. */ 1158 if (forward_wakeup_use_loop) { 1159 if (CPU_CMP(&map, &map2)) { 1160 printf("map != map2, loop method preferred\n"); 1161 map = map2; 1162 } 1163 } 1164 } else { 1165 map = map2; 1166 } 1167 1168 /* If we only allow a specific CPU, then mask off all the others. */ 1169 if (cpunum != NOCPU) { 1170 KASSERT((cpunum <= mp_maxcpus),("forward_wakeup: bad cpunum.")); 1171 iscpuset = CPU_ISSET(cpunum, &map); 1172 if (iscpuset == 0) 1173 CPU_ZERO(&map); 1174 else 1175 CPU_SETOF(cpunum, &map); 1176 } 1177 if (!CPU_EMPTY(&map)) { 1178 forward_wakeups_delivered++; 1179 STAILQ_FOREACH(pc, &cpuhead, pc_allcpu) { 1180 id = pc->pc_cpuid; 1181 if (!CPU_ISSET(id, &map)) 1182 continue; 1183 if (cpu_idle_wakeup(pc->pc_cpuid)) 1184 CPU_CLR(id, &map); 1185 } 1186 if (!CPU_EMPTY(&map)) 1187 ipi_selected(map, IPI_AST); 1188 return (1); 1189 } 1190 if (cpunum == NOCPU) 1191 printf("forward_wakeup: Idle processor not found\n"); 1192 return (0); 1193 } 1194 1195 static void 1196 kick_other_cpu(int pri, int cpuid) 1197 { 1198 struct pcpu *pcpu; 1199 int cpri; 1200 1201 pcpu = pcpu_find(cpuid); 1202 if (CPU_ISSET(cpuid, &idle_cpus_mask)) { 1203 forward_wakeups_delivered++; 1204 if (!cpu_idle_wakeup(cpuid)) 1205 ipi_cpu(cpuid, IPI_AST); 1206 return; 1207 } 1208 1209 cpri = pcpu->pc_curthread->td_priority; 1210 if (pri >= cpri) 1211 return; 1212 1213 #if defined(IPI_PREEMPTION) && defined(PREEMPTION) 1214 #if !defined(FULL_PREEMPTION) 1215 if (pri <= PRI_MAX_ITHD) 1216 #endif /* ! FULL_PREEMPTION */ 1217 { 1218 ipi_cpu(cpuid, IPI_PREEMPT); 1219 return; 1220 } 1221 #endif /* defined(IPI_PREEMPTION) && defined(PREEMPTION) */ 1222 1223 pcpu->pc_curthread->td_flags |= TDF_NEEDRESCHED; 1224 ipi_cpu(cpuid, IPI_AST); 1225 return; 1226 } 1227 #endif /* SMP */ 1228 1229 #ifdef SMP 1230 static int 1231 sched_pickcpu(struct thread *td) 1232 { 1233 int best, cpu; 1234 1235 mtx_assert(&sched_lock, MA_OWNED); 1236 1237 if (td->td_lastcpu != NOCPU && THREAD_CAN_SCHED(td, td->td_lastcpu)) 1238 best = td->td_lastcpu; 1239 else 1240 best = NOCPU; 1241 CPU_FOREACH(cpu) { 1242 if (!THREAD_CAN_SCHED(td, cpu)) 1243 continue; 1244 1245 if (best == NOCPU) 1246 best = cpu; 1247 else if (runq_length[cpu] < runq_length[best]) 1248 best = cpu; 1249 } 1250 KASSERT(best != NOCPU, ("no valid CPUs")); 1251 1252 return (best); 1253 } 1254 #endif 1255 1256 void 1257 sched_add(struct thread *td, int flags) 1258 #ifdef SMP 1259 { 1260 cpuset_t tidlemsk; 1261 struct td_sched *ts; 1262 u_int cpu, cpuid; 1263 int forwarded = 0; 1264 int single_cpu = 0; 1265 1266 ts = td_get_sched(td); 1267 THREAD_LOCK_ASSERT(td, MA_OWNED); 1268 KASSERT((td->td_inhibitors == 0), 1269 ("sched_add: trying to run inhibited thread")); 1270 KASSERT((TD_CAN_RUN(td) || TD_IS_RUNNING(td)), 1271 ("sched_add: bad thread state")); 1272 KASSERT(td->td_flags & TDF_INMEM, 1273 ("sched_add: thread swapped out")); 1274 1275 KTR_STATE2(KTR_SCHED, "thread", sched_tdname(td), "runq add", 1276 "prio:%d", td->td_priority, KTR_ATTR_LINKED, 1277 sched_tdname(curthread)); 1278 KTR_POINT1(KTR_SCHED, "thread", sched_tdname(curthread), "wokeup", 1279 KTR_ATTR_LINKED, sched_tdname(td)); 1280 SDT_PROBE4(sched, , , enqueue, td, td->td_proc, NULL, 1281 flags & SRQ_PREEMPTED); 1282 1283 1284 /* 1285 * Now that the thread is moving to the run-queue, set the lock 1286 * to the scheduler's lock. 1287 */ 1288 if (td->td_lock != &sched_lock) { 1289 mtx_lock_spin(&sched_lock); 1290 thread_lock_set(td, &sched_lock); 1291 } 1292 TD_SET_RUNQ(td); 1293 1294 /* 1295 * If SMP is started and the thread is pinned or otherwise limited to 1296 * a specific set of CPUs, queue the thread to a per-CPU run queue. 1297 * Otherwise, queue the thread to the global run queue. 1298 * 1299 * If SMP has not yet been started we must use the global run queue 1300 * as per-CPU state may not be initialized yet and we may crash if we 1301 * try to access the per-CPU run queues. 1302 */ 1303 if (smp_started && (td->td_pinned != 0 || td->td_flags & TDF_BOUND || 1304 ts->ts_flags & TSF_AFFINITY)) { 1305 if (td->td_pinned != 0) 1306 cpu = td->td_lastcpu; 1307 else if (td->td_flags & TDF_BOUND) { 1308 /* Find CPU from bound runq. */ 1309 KASSERT(SKE_RUNQ_PCPU(ts), 1310 ("sched_add: bound td_sched not on cpu runq")); 1311 cpu = ts->ts_runq - &runq_pcpu[0]; 1312 } else 1313 /* Find a valid CPU for our cpuset */ 1314 cpu = sched_pickcpu(td); 1315 ts->ts_runq = &runq_pcpu[cpu]; 1316 single_cpu = 1; 1317 CTR3(KTR_RUNQ, 1318 "sched_add: Put td_sched:%p(td:%p) on cpu%d runq", ts, td, 1319 cpu); 1320 } else { 1321 CTR2(KTR_RUNQ, 1322 "sched_add: adding td_sched:%p (td:%p) to gbl runq", ts, 1323 td); 1324 cpu = NOCPU; 1325 ts->ts_runq = &runq; 1326 } 1327 1328 if ((td->td_flags & TDF_NOLOAD) == 0) 1329 sched_load_add(); 1330 runq_add(ts->ts_runq, td, flags); 1331 if (cpu != NOCPU) 1332 runq_length[cpu]++; 1333 1334 cpuid = PCPU_GET(cpuid); 1335 if (single_cpu && cpu != cpuid) { 1336 kick_other_cpu(td->td_priority, cpu); 1337 } else { 1338 if (!single_cpu) { 1339 tidlemsk = idle_cpus_mask; 1340 CPU_NAND(&tidlemsk, &hlt_cpus_mask); 1341 CPU_CLR(cpuid, &tidlemsk); 1342 1343 if (!CPU_ISSET(cpuid, &idle_cpus_mask) && 1344 ((flags & SRQ_INTR) == 0) && 1345 !CPU_EMPTY(&tidlemsk)) 1346 forwarded = forward_wakeup(cpu); 1347 } 1348 1349 if (!forwarded) { 1350 if (!maybe_preempt(td)) 1351 maybe_resched(td); 1352 } 1353 } 1354 } 1355 #else /* SMP */ 1356 { 1357 struct td_sched *ts; 1358 1359 ts = td_get_sched(td); 1360 THREAD_LOCK_ASSERT(td, MA_OWNED); 1361 KASSERT((td->td_inhibitors == 0), 1362 ("sched_add: trying to run inhibited thread")); 1363 KASSERT((TD_CAN_RUN(td) || TD_IS_RUNNING(td)), 1364 ("sched_add: bad thread state")); 1365 KASSERT(td->td_flags & TDF_INMEM, 1366 ("sched_add: thread swapped out")); 1367 KTR_STATE2(KTR_SCHED, "thread", sched_tdname(td), "runq add", 1368 "prio:%d", td->td_priority, KTR_ATTR_LINKED, 1369 sched_tdname(curthread)); 1370 KTR_POINT1(KTR_SCHED, "thread", sched_tdname(curthread), "wokeup", 1371 KTR_ATTR_LINKED, sched_tdname(td)); 1372 SDT_PROBE4(sched, , , enqueue, td, td->td_proc, NULL, 1373 flags & SRQ_PREEMPTED); 1374 1375 /* 1376 * Now that the thread is moving to the run-queue, set the lock 1377 * to the scheduler's lock. 1378 */ 1379 if (td->td_lock != &sched_lock) { 1380 mtx_lock_spin(&sched_lock); 1381 thread_lock_set(td, &sched_lock); 1382 } 1383 TD_SET_RUNQ(td); 1384 CTR2(KTR_RUNQ, "sched_add: adding td_sched:%p (td:%p) to runq", ts, td); 1385 ts->ts_runq = &runq; 1386 1387 if ((td->td_flags & TDF_NOLOAD) == 0) 1388 sched_load_add(); 1389 runq_add(ts->ts_runq, td, flags); 1390 if (!maybe_preempt(td)) 1391 maybe_resched(td); 1392 } 1393 #endif /* SMP */ 1394 1395 void 1396 sched_rem(struct thread *td) 1397 { 1398 struct td_sched *ts; 1399 1400 ts = td_get_sched(td); 1401 KASSERT(td->td_flags & TDF_INMEM, 1402 ("sched_rem: thread swapped out")); 1403 KASSERT(TD_ON_RUNQ(td), 1404 ("sched_rem: thread not on run queue")); 1405 mtx_assert(&sched_lock, MA_OWNED); 1406 KTR_STATE2(KTR_SCHED, "thread", sched_tdname(td), "runq rem", 1407 "prio:%d", td->td_priority, KTR_ATTR_LINKED, 1408 sched_tdname(curthread)); 1409 SDT_PROBE3(sched, , , dequeue, td, td->td_proc, NULL); 1410 1411 if ((td->td_flags & TDF_NOLOAD) == 0) 1412 sched_load_rem(); 1413 #ifdef SMP 1414 if (ts->ts_runq != &runq) 1415 runq_length[ts->ts_runq - runq_pcpu]--; 1416 #endif 1417 runq_remove(ts->ts_runq, td); 1418 TD_SET_CAN_RUN(td); 1419 } 1420 1421 /* 1422 * Select threads to run. Note that running threads still consume a 1423 * slot. 1424 */ 1425 struct thread * 1426 sched_choose(void) 1427 { 1428 struct thread *td; 1429 struct runq *rq; 1430 1431 mtx_assert(&sched_lock, MA_OWNED); 1432 #ifdef SMP 1433 struct thread *tdcpu; 1434 1435 rq = &runq; 1436 td = runq_choose_fuzz(&runq, runq_fuzz); 1437 tdcpu = runq_choose(&runq_pcpu[PCPU_GET(cpuid)]); 1438 1439 if (td == NULL || 1440 (tdcpu != NULL && 1441 tdcpu->td_priority < td->td_priority)) { 1442 CTR2(KTR_RUNQ, "choosing td %p from pcpu runq %d", tdcpu, 1443 PCPU_GET(cpuid)); 1444 td = tdcpu; 1445 rq = &runq_pcpu[PCPU_GET(cpuid)]; 1446 } else { 1447 CTR1(KTR_RUNQ, "choosing td_sched %p from main runq", td); 1448 } 1449 1450 #else 1451 rq = &runq; 1452 td = runq_choose(&runq); 1453 #endif 1454 1455 if (td) { 1456 #ifdef SMP 1457 if (td == tdcpu) 1458 runq_length[PCPU_GET(cpuid)]--; 1459 #endif 1460 runq_remove(rq, td); 1461 td->td_flags |= TDF_DIDRUN; 1462 1463 KASSERT(td->td_flags & TDF_INMEM, 1464 ("sched_choose: thread swapped out")); 1465 return (td); 1466 } 1467 return (PCPU_GET(idlethread)); 1468 } 1469 1470 void 1471 sched_preempt(struct thread *td) 1472 { 1473 1474 SDT_PROBE2(sched, , , surrender, td, td->td_proc); 1475 thread_lock(td); 1476 if (td->td_critnest > 1) 1477 td->td_owepreempt = 1; 1478 else 1479 mi_switch(SW_INVOL | SW_PREEMPT | SWT_PREEMPT, NULL); 1480 thread_unlock(td); 1481 } 1482 1483 void 1484 sched_userret_slowpath(struct thread *td) 1485 { 1486 1487 thread_lock(td); 1488 td->td_priority = td->td_user_pri; 1489 td->td_base_pri = td->td_user_pri; 1490 thread_unlock(td); 1491 } 1492 1493 void 1494 sched_bind(struct thread *td, int cpu) 1495 { 1496 struct td_sched *ts; 1497 1498 THREAD_LOCK_ASSERT(td, MA_OWNED|MA_NOTRECURSED); 1499 KASSERT(td == curthread, ("sched_bind: can only bind curthread")); 1500 1501 ts = td_get_sched(td); 1502 1503 td->td_flags |= TDF_BOUND; 1504 #ifdef SMP 1505 ts->ts_runq = &runq_pcpu[cpu]; 1506 if (PCPU_GET(cpuid) == cpu) 1507 return; 1508 1509 mi_switch(SW_VOL, NULL); 1510 #endif 1511 } 1512 1513 void 1514 sched_unbind(struct thread* td) 1515 { 1516 THREAD_LOCK_ASSERT(td, MA_OWNED); 1517 KASSERT(td == curthread, ("sched_unbind: can only bind curthread")); 1518 td->td_flags &= ~TDF_BOUND; 1519 } 1520 1521 int 1522 sched_is_bound(struct thread *td) 1523 { 1524 THREAD_LOCK_ASSERT(td, MA_OWNED); 1525 return (td->td_flags & TDF_BOUND); 1526 } 1527 1528 void 1529 sched_relinquish(struct thread *td) 1530 { 1531 thread_lock(td); 1532 mi_switch(SW_VOL | SWT_RELINQUISH, NULL); 1533 thread_unlock(td); 1534 } 1535 1536 int 1537 sched_load(void) 1538 { 1539 return (sched_tdcnt); 1540 } 1541 1542 int 1543 sched_sizeof_proc(void) 1544 { 1545 return (sizeof(struct proc)); 1546 } 1547 1548 int 1549 sched_sizeof_thread(void) 1550 { 1551 return (sizeof(struct thread) + sizeof(struct td_sched)); 1552 } 1553 1554 fixpt_t 1555 sched_pctcpu(struct thread *td) 1556 { 1557 struct td_sched *ts; 1558 1559 THREAD_LOCK_ASSERT(td, MA_OWNED); 1560 ts = td_get_sched(td); 1561 return (ts->ts_pctcpu); 1562 } 1563 1564 #ifdef RACCT 1565 /* 1566 * Calculates the contribution to the thread cpu usage for the latest 1567 * (unfinished) second. 1568 */ 1569 fixpt_t 1570 sched_pctcpu_delta(struct thread *td) 1571 { 1572 struct td_sched *ts; 1573 fixpt_t delta; 1574 int realstathz; 1575 1576 THREAD_LOCK_ASSERT(td, MA_OWNED); 1577 ts = td_get_sched(td); 1578 delta = 0; 1579 realstathz = stathz ? stathz : hz; 1580 if (ts->ts_cpticks != 0) { 1581 #if (FSHIFT >= CCPU_SHIFT) 1582 delta = (realstathz == 100) 1583 ? ((fixpt_t) ts->ts_cpticks) << 1584 (FSHIFT - CCPU_SHIFT) : 1585 100 * (((fixpt_t) ts->ts_cpticks) 1586 << (FSHIFT - CCPU_SHIFT)) / realstathz; 1587 #else 1588 delta = ((FSCALE - ccpu) * 1589 (ts->ts_cpticks * 1590 FSCALE / realstathz)) >> FSHIFT; 1591 #endif 1592 } 1593 1594 return (delta); 1595 } 1596 #endif 1597 1598 u_int 1599 sched_estcpu(struct thread *td) 1600 { 1601 1602 return (td_get_sched(td)->ts_estcpu); 1603 } 1604 1605 /* 1606 * The actual idle process. 1607 */ 1608 void 1609 sched_idletd(void *dummy) 1610 { 1611 struct pcpuidlestat *stat; 1612 1613 THREAD_NO_SLEEPING(); 1614 stat = DPCPU_PTR(idlestat); 1615 for (;;) { 1616 mtx_assert(&Giant, MA_NOTOWNED); 1617 1618 while (sched_runnable() == 0) { 1619 cpu_idle(stat->idlecalls + stat->oldidlecalls > 64); 1620 stat->idlecalls++; 1621 } 1622 1623 mtx_lock_spin(&sched_lock); 1624 mi_switch(SW_VOL | SWT_IDLE, NULL); 1625 mtx_unlock_spin(&sched_lock); 1626 } 1627 } 1628 1629 /* 1630 * A CPU is entering for the first time or a thread is exiting. 1631 */ 1632 void 1633 sched_throw(struct thread *td) 1634 { 1635 /* 1636 * Correct spinlock nesting. The idle thread context that we are 1637 * borrowing was created so that it would start out with a single 1638 * spin lock (sched_lock) held in fork_trampoline(). Since we've 1639 * explicitly acquired locks in this function, the nesting count 1640 * is now 2 rather than 1. Since we are nested, calling 1641 * spinlock_exit() will simply adjust the counts without allowing 1642 * spin lock using code to interrupt us. 1643 */ 1644 if (td == NULL) { 1645 mtx_lock_spin(&sched_lock); 1646 spinlock_exit(); 1647 PCPU_SET(switchtime, cpu_ticks()); 1648 PCPU_SET(switchticks, ticks); 1649 } else { 1650 lock_profile_release_lock(&sched_lock.lock_object); 1651 MPASS(td->td_lock == &sched_lock); 1652 td->td_lastcpu = td->td_oncpu; 1653 td->td_oncpu = NOCPU; 1654 } 1655 mtx_assert(&sched_lock, MA_OWNED); 1656 KASSERT(curthread->td_md.md_spinlock_count == 1, ("invalid count")); 1657 cpu_throw(td, choosethread()); /* doesn't return */ 1658 } 1659 1660 void 1661 sched_fork_exit(struct thread *td) 1662 { 1663 1664 /* 1665 * Finish setting up thread glue so that it begins execution in a 1666 * non-nested critical section with sched_lock held but not recursed. 1667 */ 1668 td->td_oncpu = PCPU_GET(cpuid); 1669 sched_lock.mtx_lock = (uintptr_t)td; 1670 lock_profile_obtain_lock_success(&sched_lock.lock_object, 1671 0, 0, __FILE__, __LINE__); 1672 THREAD_LOCK_ASSERT(td, MA_OWNED | MA_NOTRECURSED); 1673 1674 KTR_STATE1(KTR_SCHED, "thread", sched_tdname(td), "running", 1675 "prio:%d", td->td_priority); 1676 SDT_PROBE0(sched, , , on__cpu); 1677 } 1678 1679 char * 1680 sched_tdname(struct thread *td) 1681 { 1682 #ifdef KTR 1683 struct td_sched *ts; 1684 1685 ts = td_get_sched(td); 1686 if (ts->ts_name[0] == '\0') 1687 snprintf(ts->ts_name, sizeof(ts->ts_name), 1688 "%s tid %d", td->td_name, td->td_tid); 1689 return (ts->ts_name); 1690 #else 1691 return (td->td_name); 1692 #endif 1693 } 1694 1695 #ifdef KTR 1696 void 1697 sched_clear_tdname(struct thread *td) 1698 { 1699 struct td_sched *ts; 1700 1701 ts = td_get_sched(td); 1702 ts->ts_name[0] = '\0'; 1703 } 1704 #endif 1705 1706 void 1707 sched_affinity(struct thread *td) 1708 { 1709 #ifdef SMP 1710 struct td_sched *ts; 1711 int cpu; 1712 1713 THREAD_LOCK_ASSERT(td, MA_OWNED); 1714 1715 /* 1716 * Set the TSF_AFFINITY flag if there is at least one CPU this 1717 * thread can't run on. 1718 */ 1719 ts = td_get_sched(td); 1720 ts->ts_flags &= ~TSF_AFFINITY; 1721 CPU_FOREACH(cpu) { 1722 if (!THREAD_CAN_SCHED(td, cpu)) { 1723 ts->ts_flags |= TSF_AFFINITY; 1724 break; 1725 } 1726 } 1727 1728 /* 1729 * If this thread can run on all CPUs, nothing else to do. 1730 */ 1731 if (!(ts->ts_flags & TSF_AFFINITY)) 1732 return; 1733 1734 /* Pinned threads and bound threads should be left alone. */ 1735 if (td->td_pinned != 0 || td->td_flags & TDF_BOUND) 1736 return; 1737 1738 switch (td->td_state) { 1739 case TDS_RUNQ: 1740 /* 1741 * If we are on a per-CPU runqueue that is in the set, 1742 * then nothing needs to be done. 1743 */ 1744 if (ts->ts_runq != &runq && 1745 THREAD_CAN_SCHED(td, ts->ts_runq - runq_pcpu)) 1746 return; 1747 1748 /* Put this thread on a valid per-CPU runqueue. */ 1749 sched_rem(td); 1750 sched_add(td, SRQ_BORING); 1751 break; 1752 case TDS_RUNNING: 1753 /* 1754 * See if our current CPU is in the set. If not, force a 1755 * context switch. 1756 */ 1757 if (THREAD_CAN_SCHED(td, td->td_oncpu)) 1758 return; 1759 1760 td->td_flags |= TDF_NEEDRESCHED; 1761 if (td != curthread) 1762 ipi_cpu(cpu, IPI_AST); 1763 break; 1764 default: 1765 break; 1766 } 1767 #endif 1768 }
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