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 #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/runq.h> 52 #include <sys/sched.h> 53 #include <sys/sdt.h> 54 #include <sys/smp.h> 55 #include <sys/sysctl.h> 56 #include <sys/sx.h> 57 #include <sys/turnstile.h> 58 #include <sys/umtxvar.h> 59 #include <machine/pcb.h> 60 #include <machine/smp.h> 61 62 #ifdef HWPMC_HOOKS 63 #include <sys/pmckern.h> 64 #endif 65 66 #ifdef KDTRACE_HOOKS 67 #include <sys/dtrace_bsd.h> 68 int __read_mostly dtrace_vtime_active; 69 dtrace_vtime_switch_func_t dtrace_vtime_switch_func; 70 #endif 71 72 /* 73 * INVERSE_ESTCPU_WEIGHT is only suitable for statclock() frequencies in 74 * the range 100-256 Hz (approximately). 75 */ 76 #ifdef SMP 77 #define INVERSE_ESTCPU_WEIGHT (8 * smp_cpus) 78 #else 79 #define INVERSE_ESTCPU_WEIGHT 8 /* 1 / (priorities per estcpu level). */ 80 #endif 81 #define NICE_WEIGHT 1 /* Priorities per nice level. */ 82 #define ESTCPULIM(e) \ 83 min((e), INVERSE_ESTCPU_WEIGHT * \ 84 (NICE_WEIGHT * (PRIO_MAX - PRIO_MIN) + \ 85 PRI_MAX_TIMESHARE - PRI_MIN_TIMESHARE) \ 86 + INVERSE_ESTCPU_WEIGHT - 1) 87 88 #define TS_NAME_LEN (MAXCOMLEN + sizeof(" td ") + sizeof(__XSTRING(UINT_MAX))) 89 90 /* 91 * The schedulable entity that runs a context. 92 * This is an extension to the thread structure and is tailored to 93 * the requirements of this scheduler. 94 * All fields are protected by the scheduler lock. 95 */ 96 struct td_sched { 97 fixpt_t ts_pctcpu; /* %cpu during p_swtime. */ 98 u_int ts_estcpu; /* Estimated cpu utilization. */ 99 int ts_cpticks; /* Ticks of cpu time. */ 100 int ts_slptime; /* Seconds !RUNNING. */ 101 int ts_slice; /* Remaining part of time slice. */ 102 int ts_flags; 103 struct runq *ts_runq; /* runq the thread is currently on */ 104 #ifdef KTR 105 char ts_name[TS_NAME_LEN]; 106 #endif 107 }; 108 109 /* flags kept in td_flags */ 110 #define TDF_DIDRUN TDF_SCHED0 /* thread actually ran. */ 111 #define TDF_BOUND TDF_SCHED1 /* Bound to one CPU. */ 112 #define TDF_SLICEEND TDF_SCHED2 /* Thread time slice is over. */ 113 114 /* flags kept in ts_flags */ 115 #define TSF_AFFINITY 0x0001 /* Has a non-"full" CPU set. */ 116 117 #define SKE_RUNQ_PCPU(ts) \ 118 ((ts)->ts_runq != 0 && (ts)->ts_runq != &runq) 119 120 #define THREAD_CAN_SCHED(td, cpu) \ 121 CPU_ISSET((cpu), &(td)->td_cpuset->cs_mask) 122 123 _Static_assert(sizeof(struct thread) + sizeof(struct td_sched) <= 124 sizeof(struct thread0_storage), 125 "increase struct thread0_storage.t0st_sched size"); 126 127 static struct mtx sched_lock; 128 129 static int realstathz = 127; /* stathz is sometimes 0 and run off of hz. */ 130 static int sched_tdcnt; /* Total runnable threads in the system. */ 131 static int sched_slice = 12; /* Thread run time before rescheduling. */ 132 133 static void setup_runqs(void); 134 static void schedcpu(void); 135 static void schedcpu_thread(void); 136 static void sched_priority(struct thread *td, u_char prio); 137 static void sched_setup(void *dummy); 138 static void maybe_resched(struct thread *td); 139 static void updatepri(struct thread *td); 140 static void resetpriority(struct thread *td); 141 static void resetpriority_thread(struct thread *td); 142 #ifdef SMP 143 static int sched_pickcpu(struct thread *td); 144 static int forward_wakeup(int cpunum); 145 static void kick_other_cpu(int pri, int cpuid); 146 #endif 147 148 static struct kproc_desc sched_kp = { 149 "schedcpu", 150 schedcpu_thread, 151 NULL 152 }; 153 SYSINIT(schedcpu, SI_SUB_LAST, SI_ORDER_FIRST, kproc_start, 154 &sched_kp); 155 SYSINIT(sched_setup, SI_SUB_RUN_QUEUE, SI_ORDER_FIRST, sched_setup, NULL); 156 157 static void sched_initticks(void *dummy); 158 SYSINIT(sched_initticks, SI_SUB_CLOCKS, SI_ORDER_THIRD, sched_initticks, 159 NULL); 160 161 /* 162 * Global run queue. 163 */ 164 static struct runq runq; 165 166 #ifdef SMP 167 /* 168 * Per-CPU run queues 169 */ 170 static struct runq runq_pcpu[MAXCPU]; 171 long runq_length[MAXCPU]; 172 173 static cpuset_t idle_cpus_mask; 174 #endif 175 176 struct pcpuidlestat { 177 u_int idlecalls; 178 u_int oldidlecalls; 179 }; 180 DPCPU_DEFINE_STATIC(struct pcpuidlestat, idlestat); 181 182 static void 183 setup_runqs(void) 184 { 185 #ifdef SMP 186 int i; 187 188 for (i = 0; i < MAXCPU; ++i) 189 runq_init(&runq_pcpu[i]); 190 #endif 191 192 runq_init(&runq); 193 } 194 195 static int 196 sysctl_kern_quantum(SYSCTL_HANDLER_ARGS) 197 { 198 int error, new_val, period; 199 200 period = 1000000 / realstathz; 201 new_val = period * sched_slice; 202 error = sysctl_handle_int(oidp, &new_val, 0, req); 203 if (error != 0 || req->newptr == NULL) 204 return (error); 205 if (new_val <= 0) 206 return (EINVAL); 207 sched_slice = imax(1, (new_val + period / 2) / period); 208 hogticks = imax(1, (2 * hz * sched_slice + realstathz / 2) / 209 realstathz); 210 return (0); 211 } 212 213 SYSCTL_NODE(_kern, OID_AUTO, sched, CTLFLAG_RD | CTLFLAG_MPSAFE, 0, 214 "Scheduler"); 215 216 SYSCTL_STRING(_kern_sched, OID_AUTO, name, CTLFLAG_RD, "4BSD", 0, 217 "Scheduler name"); 218 SYSCTL_PROC(_kern_sched, OID_AUTO, quantum, 219 CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_MPSAFE, NULL, 0, 220 sysctl_kern_quantum, "I", 221 "Quantum for timeshare threads in microseconds"); 222 SYSCTL_INT(_kern_sched, OID_AUTO, slice, CTLFLAG_RW, &sched_slice, 0, 223 "Quantum for timeshare threads in stathz ticks"); 224 #ifdef SMP 225 /* Enable forwarding of wakeups to all other cpus */ 226 static SYSCTL_NODE(_kern_sched, OID_AUTO, ipiwakeup, 227 CTLFLAG_RD | CTLFLAG_MPSAFE, NULL, 228 "Kernel SMP"); 229 230 static int runq_fuzz = 1; 231 SYSCTL_INT(_kern_sched, OID_AUTO, runq_fuzz, CTLFLAG_RW, &runq_fuzz, 0, ""); 232 233 static int forward_wakeup_enabled = 1; 234 SYSCTL_INT(_kern_sched_ipiwakeup, OID_AUTO, enabled, CTLFLAG_RW, 235 &forward_wakeup_enabled, 0, 236 "Forwarding of wakeup to idle CPUs"); 237 238 static int forward_wakeups_requested = 0; 239 SYSCTL_INT(_kern_sched_ipiwakeup, OID_AUTO, requested, CTLFLAG_RD, 240 &forward_wakeups_requested, 0, 241 "Requests for Forwarding of wakeup to idle CPUs"); 242 243 static int forward_wakeups_delivered = 0; 244 SYSCTL_INT(_kern_sched_ipiwakeup, OID_AUTO, delivered, CTLFLAG_RD, 245 &forward_wakeups_delivered, 0, 246 "Completed Forwarding of wakeup to idle CPUs"); 247 248 static int forward_wakeup_use_mask = 1; 249 SYSCTL_INT(_kern_sched_ipiwakeup, OID_AUTO, usemask, CTLFLAG_RW, 250 &forward_wakeup_use_mask, 0, 251 "Use the mask of idle cpus"); 252 253 static int forward_wakeup_use_loop = 0; 254 SYSCTL_INT(_kern_sched_ipiwakeup, OID_AUTO, useloop, CTLFLAG_RW, 255 &forward_wakeup_use_loop, 0, 256 "Use a loop to find idle cpus"); 257 258 #endif 259 #if 0 260 static int sched_followon = 0; 261 SYSCTL_INT(_kern_sched, OID_AUTO, followon, CTLFLAG_RW, 262 &sched_followon, 0, 263 "allow threads to share a quantum"); 264 #endif 265 266 SDT_PROVIDER_DEFINE(sched); 267 268 SDT_PROBE_DEFINE3(sched, , , change__pri, "struct thread *", 269 "struct proc *", "uint8_t"); 270 SDT_PROBE_DEFINE3(sched, , , dequeue, "struct thread *", 271 "struct proc *", "void *"); 272 SDT_PROBE_DEFINE4(sched, , , enqueue, "struct thread *", 273 "struct proc *", "void *", "int"); 274 SDT_PROBE_DEFINE4(sched, , , lend__pri, "struct thread *", 275 "struct proc *", "uint8_t", "struct thread *"); 276 SDT_PROBE_DEFINE2(sched, , , load__change, "int", "int"); 277 SDT_PROBE_DEFINE2(sched, , , off__cpu, "struct thread *", 278 "struct proc *"); 279 SDT_PROBE_DEFINE(sched, , , on__cpu); 280 SDT_PROBE_DEFINE(sched, , , remain__cpu); 281 SDT_PROBE_DEFINE2(sched, , , surrender, "struct thread *", 282 "struct proc *"); 283 284 static __inline void 285 sched_load_add(void) 286 { 287 288 sched_tdcnt++; 289 KTR_COUNTER0(KTR_SCHED, "load", "global load", sched_tdcnt); 290 SDT_PROBE2(sched, , , load__change, NOCPU, sched_tdcnt); 291 } 292 293 static __inline void 294 sched_load_rem(void) 295 { 296 297 sched_tdcnt--; 298 KTR_COUNTER0(KTR_SCHED, "load", "global load", sched_tdcnt); 299 SDT_PROBE2(sched, , , load__change, NOCPU, sched_tdcnt); 300 } 301 /* 302 * Arrange to reschedule if necessary, taking the priorities and 303 * schedulers into account. 304 */ 305 static void 306 maybe_resched(struct thread *td) 307 { 308 309 THREAD_LOCK_ASSERT(td, MA_OWNED); 310 if (td->td_priority < curthread->td_priority) 311 ast_sched_locked(curthread, TDA_SCHED); 312 } 313 314 /* 315 * This function is called when a thread is about to be put on run queue 316 * because it has been made runnable or its priority has been adjusted. It 317 * determines if the new thread should preempt the current thread. If so, 318 * it sets td_owepreempt to request a preemption. 319 */ 320 int 321 maybe_preempt(struct thread *td) 322 { 323 #ifdef PREEMPTION 324 struct thread *ctd; 325 int cpri, pri; 326 327 /* 328 * The new thread should not preempt the current thread if any of the 329 * following conditions are true: 330 * 331 * - The kernel is in the throes of crashing (panicstr). 332 * - The current thread has a higher (numerically lower) or 333 * equivalent priority. Note that this prevents curthread from 334 * trying to preempt to itself. 335 * - The current thread has an inhibitor set or is in the process of 336 * exiting. In this case, the current thread is about to switch 337 * out anyways, so there's no point in preempting. If we did, 338 * the current thread would not be properly resumed as well, so 339 * just avoid that whole landmine. 340 * - If the new thread's priority is not a realtime priority and 341 * the current thread's priority is not an idle priority and 342 * FULL_PREEMPTION is disabled. 343 * 344 * If all of these conditions are false, but the current thread is in 345 * a nested critical section, then we have to defer the preemption 346 * until we exit the critical section. Otherwise, switch immediately 347 * to the new thread. 348 */ 349 ctd = curthread; 350 THREAD_LOCK_ASSERT(td, MA_OWNED); 351 KASSERT((td->td_inhibitors == 0), 352 ("maybe_preempt: trying to run inhibited thread")); 353 pri = td->td_priority; 354 cpri = ctd->td_priority; 355 if (KERNEL_PANICKED() || pri >= cpri /* || dumping */ || 356 TD_IS_INHIBITED(ctd)) 357 return (0); 358 #ifndef FULL_PREEMPTION 359 if (pri > PRI_MAX_ITHD && cpri < PRI_MIN_IDLE) 360 return (0); 361 #endif 362 363 CTR0(KTR_PROC, "maybe_preempt: scheduling preemption"); 364 ctd->td_owepreempt = 1; 365 return (1); 366 #else 367 return (0); 368 #endif 369 } 370 371 /* 372 * Constants for digital decay and forget: 373 * 90% of (ts_estcpu) usage in 5 * loadav time 374 * 95% of (ts_pctcpu) usage in 60 seconds (load insensitive) 375 * Note that, as ps(1) mentions, this can let percentages 376 * total over 100% (I've seen 137.9% for 3 processes). 377 * 378 * Note that schedclock() updates ts_estcpu and p_cpticks asynchronously. 379 * 380 * We wish to decay away 90% of ts_estcpu in (5 * loadavg) seconds. 381 * That is, the system wants to compute a value of decay such 382 * that the following for loop: 383 * for (i = 0; i < (5 * loadavg); i++) 384 * ts_estcpu *= decay; 385 * will compute 386 * ts_estcpu *= 0.1; 387 * for all values of loadavg: 388 * 389 * Mathematically this loop can be expressed by saying: 390 * decay ** (5 * loadavg) ~= .1 391 * 392 * The system computes decay as: 393 * decay = (2 * loadavg) / (2 * loadavg + 1) 394 * 395 * We wish to prove that the system's computation of decay 396 * will always fulfill the equation: 397 * decay ** (5 * loadavg) ~= .1 398 * 399 * If we compute b as: 400 * b = 2 * loadavg 401 * then 402 * decay = b / (b + 1) 403 * 404 * We now need to prove two things: 405 * 1) Given factor ** (5 * loadavg) ~= .1, prove factor == b/(b+1) 406 * 2) Given b/(b+1) ** power ~= .1, prove power == (5 * loadavg) 407 * 408 * Facts: 409 * For x close to zero, exp(x) =~ 1 + x, since 410 * exp(x) = 0! + x**1/1! + x**2/2! + ... . 411 * therefore exp(-1/b) =~ 1 - (1/b) = (b-1)/b. 412 * For x close to zero, ln(1+x) =~ x, since 413 * ln(1+x) = x - x**2/2 + x**3/3 - ... -1 < x < 1 414 * therefore ln(b/(b+1)) = ln(1 - 1/(b+1)) =~ -1/(b+1). 415 * ln(.1) =~ -2.30 416 * 417 * Proof of (1): 418 * Solve (factor)**(power) =~ .1 given power (5*loadav): 419 * solving for factor, 420 * ln(factor) =~ (-2.30/5*loadav), or 421 * factor =~ exp(-1/((5/2.30)*loadav)) =~ exp(-1/(2*loadav)) = 422 * exp(-1/b) =~ (b-1)/b =~ b/(b+1). QED 423 * 424 * Proof of (2): 425 * Solve (factor)**(power) =~ .1 given factor == (b/(b+1)): 426 * solving for power, 427 * power*ln(b/(b+1)) =~ -2.30, or 428 * power =~ 2.3 * (b + 1) = 4.6*loadav + 2.3 =~ 5*loadav. QED 429 * 430 * Actual power values for the implemented algorithm are as follows: 431 * loadav: 1 2 3 4 432 * power: 5.68 10.32 14.94 19.55 433 */ 434 435 /* calculations for digital decay to forget 90% of usage in 5*loadav sec */ 436 #define loadfactor(loadav) (2 * (loadav)) 437 #define decay_cpu(loadfac, cpu) (((loadfac) * (cpu)) / ((loadfac) + FSCALE)) 438 439 /* decay 95% of `ts_pctcpu' in 60 seconds; see CCPU_SHIFT before changing */ 440 static fixpt_t ccpu = 0.95122942450071400909 * FSCALE; /* exp(-1/20) */ 441 SYSCTL_UINT(_kern, OID_AUTO, ccpu, CTLFLAG_RD, &ccpu, 0, 442 "Decay factor used for updating %CPU"); 443 444 /* 445 * If `ccpu' is not equal to `exp(-1/20)' and you still want to use the 446 * faster/more-accurate formula, you'll have to estimate CCPU_SHIFT below 447 * and possibly adjust FSHIFT in "param.h" so that (FSHIFT >= CCPU_SHIFT). 448 * 449 * To estimate CCPU_SHIFT for exp(-1/20), the following formula was used: 450 * 1 - exp(-1/20) ~= 0.0487 ~= 0.0488 == 1 (fixed pt, *11* bits). 451 * 452 * If you don't want to bother with the faster/more-accurate formula, you 453 * can set CCPU_SHIFT to (FSHIFT + 1) which will use a slower/less-accurate 454 * (more general) method of calculating the %age of CPU used by a process. 455 */ 456 #define CCPU_SHIFT 11 457 458 /* 459 * Recompute process priorities, every hz ticks. 460 * MP-safe, called without the Giant mutex. 461 */ 462 /* ARGSUSED */ 463 static void 464 schedcpu(void) 465 { 466 fixpt_t loadfac = loadfactor(averunnable.ldavg[0]); 467 struct thread *td; 468 struct proc *p; 469 struct td_sched *ts; 470 int awake; 471 472 sx_slock(&allproc_lock); 473 FOREACH_PROC_IN_SYSTEM(p) { 474 PROC_LOCK(p); 475 if (p->p_state == PRS_NEW) { 476 PROC_UNLOCK(p); 477 continue; 478 } 479 FOREACH_THREAD_IN_PROC(p, td) { 480 awake = 0; 481 ts = td_get_sched(td); 482 thread_lock(td); 483 /* 484 * Increment sleep time (if sleeping). We 485 * ignore overflow, as above. 486 */ 487 /* 488 * The td_sched slptimes are not touched in wakeup 489 * because the thread may not HAVE everything in 490 * memory? XXX I think this is out of date. 491 */ 492 if (TD_ON_RUNQ(td)) { 493 awake = 1; 494 td->td_flags &= ~TDF_DIDRUN; 495 } else if (TD_IS_RUNNING(td)) { 496 awake = 1; 497 /* Do not clear TDF_DIDRUN */ 498 } else if (td->td_flags & TDF_DIDRUN) { 499 awake = 1; 500 td->td_flags &= ~TDF_DIDRUN; 501 } 502 503 /* 504 * ts_pctcpu is only for ps and ttyinfo(). 505 */ 506 ts->ts_pctcpu = (ts->ts_pctcpu * ccpu) >> FSHIFT; 507 /* 508 * If the td_sched has been idle the entire second, 509 * stop recalculating its priority until 510 * it wakes up. 511 */ 512 if (ts->ts_cpticks != 0) { 513 #if (FSHIFT >= CCPU_SHIFT) 514 ts->ts_pctcpu += (realstathz == 100) 515 ? ((fixpt_t) ts->ts_cpticks) << 516 (FSHIFT - CCPU_SHIFT) : 517 100 * (((fixpt_t) ts->ts_cpticks) 518 << (FSHIFT - CCPU_SHIFT)) / realstathz; 519 #else 520 ts->ts_pctcpu += ((FSCALE - ccpu) * 521 (ts->ts_cpticks * 522 FSCALE / realstathz)) >> FSHIFT; 523 #endif 524 ts->ts_cpticks = 0; 525 } 526 /* 527 * If there are ANY running threads in this process, 528 * then don't count it as sleeping. 529 * XXX: this is broken. 530 */ 531 if (awake) { 532 if (ts->ts_slptime > 1) { 533 /* 534 * In an ideal world, this should not 535 * happen, because whoever woke us 536 * up from the long sleep should have 537 * unwound the slptime and reset our 538 * priority before we run at the stale 539 * priority. Should KASSERT at some 540 * point when all the cases are fixed. 541 */ 542 updatepri(td); 543 } 544 ts->ts_slptime = 0; 545 } else 546 ts->ts_slptime++; 547 if (ts->ts_slptime > 1) { 548 thread_unlock(td); 549 continue; 550 } 551 ts->ts_estcpu = decay_cpu(loadfac, ts->ts_estcpu); 552 resetpriority(td); 553 resetpriority_thread(td); 554 thread_unlock(td); 555 } 556 PROC_UNLOCK(p); 557 } 558 sx_sunlock(&allproc_lock); 559 } 560 561 /* 562 * Main loop for a kthread that executes schedcpu once a second. 563 */ 564 static void 565 schedcpu_thread(void) 566 { 567 568 for (;;) { 569 schedcpu(); 570 pause("-", hz); 571 } 572 } 573 574 /* 575 * Recalculate the priority of a process after it has slept for a while. 576 * For all load averages >= 1 and max ts_estcpu of 255, sleeping for at 577 * least six times the loadfactor will decay ts_estcpu to zero. 578 */ 579 static void 580 updatepri(struct thread *td) 581 { 582 struct td_sched *ts; 583 fixpt_t loadfac; 584 unsigned int newcpu; 585 586 ts = td_get_sched(td); 587 loadfac = loadfactor(averunnable.ldavg[0]); 588 if (ts->ts_slptime > 5 * loadfac) 589 ts->ts_estcpu = 0; 590 else { 591 newcpu = ts->ts_estcpu; 592 ts->ts_slptime--; /* was incremented in schedcpu() */ 593 while (newcpu && --ts->ts_slptime) 594 newcpu = decay_cpu(loadfac, newcpu); 595 ts->ts_estcpu = newcpu; 596 } 597 } 598 599 /* 600 * Compute the priority of a process when running in user mode. 601 * Arrange to reschedule if the resulting priority is better 602 * than that of the current process. 603 */ 604 static void 605 resetpriority(struct thread *td) 606 { 607 u_int newpriority; 608 609 if (td->td_pri_class != PRI_TIMESHARE) 610 return; 611 newpriority = PUSER + 612 td_get_sched(td)->ts_estcpu / INVERSE_ESTCPU_WEIGHT + 613 NICE_WEIGHT * (td->td_proc->p_nice - PRIO_MIN); 614 newpriority = min(max(newpriority, PRI_MIN_TIMESHARE), 615 PRI_MAX_TIMESHARE); 616 sched_user_prio(td, newpriority); 617 } 618 619 /* 620 * Update the thread's priority when the associated process's user 621 * priority changes. 622 */ 623 static void 624 resetpriority_thread(struct thread *td) 625 { 626 627 /* Only change threads with a time sharing user priority. */ 628 if (td->td_priority < PRI_MIN_TIMESHARE || 629 td->td_priority > PRI_MAX_TIMESHARE) 630 return; 631 632 /* XXX the whole needresched thing is broken, but not silly. */ 633 maybe_resched(td); 634 635 sched_prio(td, td->td_user_pri); 636 } 637 638 /* ARGSUSED */ 639 static void 640 sched_setup(void *dummy) 641 { 642 643 setup_runqs(); 644 645 /* Account for thread0. */ 646 sched_load_add(); 647 } 648 649 /* 650 * This routine determines time constants after stathz and hz are setup. 651 */ 652 static void 653 sched_initticks(void *dummy) 654 { 655 656 realstathz = stathz ? stathz : hz; 657 sched_slice = realstathz / 10; /* ~100ms */ 658 hogticks = imax(1, (2 * hz * sched_slice + realstathz / 2) / 659 realstathz); 660 } 661 662 /* External interfaces start here */ 663 664 /* 665 * Very early in the boot some setup of scheduler-specific 666 * parts of proc0 and of some scheduler resources needs to be done. 667 * Called from: 668 * proc0_init() 669 */ 670 void 671 schedinit(void) 672 { 673 674 /* 675 * Set up the scheduler specific parts of thread0. 676 */ 677 thread0.td_lock = &sched_lock; 678 td_get_sched(&thread0)->ts_slice = sched_slice; 679 mtx_init(&sched_lock, "sched lock", NULL, MTX_SPIN); 680 } 681 682 void 683 schedinit_ap(void) 684 { 685 686 /* Nothing needed. */ 687 } 688 689 bool 690 sched_runnable(void) 691 { 692 #ifdef SMP 693 return (runq_not_empty(&runq) || 694 runq_not_empty(&runq_pcpu[PCPU_GET(cpuid)])); 695 #else 696 return (runq_not_empty(&runq)); 697 #endif 698 } 699 700 int 701 sched_rr_interval(void) 702 { 703 704 /* Convert sched_slice from stathz to hz. */ 705 return (imax(1, (sched_slice * hz + realstathz / 2) / realstathz)); 706 } 707 708 SCHED_STAT_DEFINE(ithread_demotions, "Interrupt thread priority demotions"); 709 SCHED_STAT_DEFINE(ithread_preemptions, 710 "Interrupt thread preemptions due to time-sharing"); 711 712 /* 713 * We adjust the priority of the current process. The priority of a 714 * process gets worse as it accumulates CPU time. The cpu usage 715 * estimator (ts_estcpu) is increased here. resetpriority() will 716 * compute a different priority each time ts_estcpu increases by 717 * INVERSE_ESTCPU_WEIGHT (until PRI_MAX_TIMESHARE is reached). The 718 * cpu usage estimator ramps up quite quickly when the process is 719 * running (linearly), and decays away exponentially, at a rate which 720 * is proportionally slower when the system is busy. The basic 721 * principle is that the system will 90% forget that the process used 722 * a lot of CPU time in 5 * loadav seconds. This causes the system to 723 * favor processes which haven't run much recently, and to round-robin 724 * among other processes. 725 */ 726 static void 727 sched_clock_tick(struct thread *td) 728 { 729 struct pcpuidlestat *stat; 730 struct td_sched *ts; 731 732 THREAD_LOCK_ASSERT(td, MA_OWNED); 733 ts = td_get_sched(td); 734 735 ts->ts_cpticks++; 736 ts->ts_estcpu = ESTCPULIM(ts->ts_estcpu + 1); 737 if ((ts->ts_estcpu % INVERSE_ESTCPU_WEIGHT) == 0) { 738 resetpriority(td); 739 resetpriority_thread(td); 740 } 741 742 /* 743 * Force a context switch if the current thread has used up a full 744 * time slice (default is 100ms). 745 */ 746 if (!TD_IS_IDLETHREAD(td) && --ts->ts_slice <= 0) { 747 ts->ts_slice = sched_slice; 748 749 /* 750 * If an ithread uses a full quantum, demote its 751 * priority and preempt it. 752 */ 753 if (PRI_BASE(td->td_pri_class) == PRI_ITHD) { 754 SCHED_STAT_INC(ithread_preemptions); 755 td->td_owepreempt = 1; 756 if (td->td_base_pri + RQ_PPQ < PRI_MAX_ITHD) { 757 SCHED_STAT_INC(ithread_demotions); 758 sched_prio(td, td->td_base_pri + RQ_PPQ); 759 } 760 } else { 761 td->td_flags |= TDF_SLICEEND; 762 ast_sched_locked(td, TDA_SCHED); 763 } 764 } 765 766 stat = DPCPU_PTR(idlestat); 767 stat->oldidlecalls = stat->idlecalls; 768 stat->idlecalls = 0; 769 } 770 771 void 772 sched_clock(struct thread *td, int cnt) 773 { 774 775 for ( ; cnt > 0; cnt--) 776 sched_clock_tick(td); 777 } 778 779 /* 780 * Charge child's scheduling CPU usage to parent. 781 */ 782 void 783 sched_exit(struct proc *p, struct thread *td) 784 { 785 786 KTR_STATE1(KTR_SCHED, "thread", sched_tdname(td), "proc exit", 787 "prio:%d", td->td_priority); 788 789 PROC_LOCK_ASSERT(p, MA_OWNED); 790 sched_exit_thread(FIRST_THREAD_IN_PROC(p), td); 791 } 792 793 void 794 sched_exit_thread(struct thread *td, struct thread *child) 795 { 796 797 KTR_STATE1(KTR_SCHED, "thread", sched_tdname(child), "exit", 798 "prio:%d", child->td_priority); 799 thread_lock(td); 800 td_get_sched(td)->ts_estcpu = ESTCPULIM(td_get_sched(td)->ts_estcpu + 801 td_get_sched(child)->ts_estcpu); 802 thread_unlock(td); 803 thread_lock(child); 804 if ((child->td_flags & TDF_NOLOAD) == 0) 805 sched_load_rem(); 806 thread_unlock(child); 807 } 808 809 void 810 sched_fork(struct thread *td, struct thread *childtd) 811 { 812 sched_fork_thread(td, childtd); 813 } 814 815 void 816 sched_fork_thread(struct thread *td, struct thread *childtd) 817 { 818 struct td_sched *ts, *tsc; 819 820 childtd->td_oncpu = NOCPU; 821 childtd->td_lastcpu = NOCPU; 822 childtd->td_lock = &sched_lock; 823 childtd->td_cpuset = cpuset_ref(td->td_cpuset); 824 childtd->td_domain.dr_policy = td->td_cpuset->cs_domain; 825 childtd->td_priority = childtd->td_base_pri; 826 ts = td_get_sched(childtd); 827 bzero(ts, sizeof(*ts)); 828 tsc = td_get_sched(td); 829 ts->ts_estcpu = tsc->ts_estcpu; 830 ts->ts_flags |= (tsc->ts_flags & TSF_AFFINITY); 831 ts->ts_slice = 1; 832 } 833 834 void 835 sched_nice(struct proc *p, int nice) 836 { 837 struct thread *td; 838 839 PROC_LOCK_ASSERT(p, MA_OWNED); 840 p->p_nice = nice; 841 FOREACH_THREAD_IN_PROC(p, td) { 842 thread_lock(td); 843 resetpriority(td); 844 resetpriority_thread(td); 845 thread_unlock(td); 846 } 847 } 848 849 void 850 sched_class(struct thread *td, int class) 851 { 852 THREAD_LOCK_ASSERT(td, MA_OWNED); 853 td->td_pri_class = class; 854 } 855 856 /* 857 * Adjust the priority of a thread. 858 */ 859 static void 860 sched_priority(struct thread *td, u_char prio) 861 { 862 863 KTR_POINT3(KTR_SCHED, "thread", sched_tdname(td), "priority change", 864 "prio:%d", td->td_priority, "new prio:%d", prio, KTR_ATTR_LINKED, 865 sched_tdname(curthread)); 866 SDT_PROBE3(sched, , , change__pri, td, td->td_proc, prio); 867 if (td != curthread && prio > td->td_priority) { 868 KTR_POINT3(KTR_SCHED, "thread", sched_tdname(curthread), 869 "lend prio", "prio:%d", td->td_priority, "new prio:%d", 870 prio, KTR_ATTR_LINKED, sched_tdname(td)); 871 SDT_PROBE4(sched, , , lend__pri, td, td->td_proc, prio, 872 curthread); 873 } 874 THREAD_LOCK_ASSERT(td, MA_OWNED); 875 if (td->td_priority == prio) 876 return; 877 td->td_priority = prio; 878 if (TD_ON_RUNQ(td) && td->td_rqindex != RQ_PRI_TO_QUEUE_IDX(prio)) { 879 sched_rem(td); 880 sched_add(td, SRQ_BORING | SRQ_HOLDTD); 881 } 882 } 883 884 /* 885 * Update a thread's priority when it is lent another thread's 886 * priority. 887 */ 888 void 889 sched_lend_prio(struct thread *td, u_char prio) 890 { 891 892 td->td_flags |= TDF_BORROWING; 893 sched_priority(td, prio); 894 } 895 896 /* 897 * Restore a thread's priority when priority propagation is 898 * over. The prio argument is the minimum priority the thread 899 * needs to have to satisfy other possible priority lending 900 * requests. If the thread's regulary priority is less 901 * important than prio the thread will keep a priority boost 902 * of prio. 903 */ 904 void 905 sched_unlend_prio(struct thread *td, u_char prio) 906 { 907 u_char base_pri; 908 909 if (td->td_base_pri >= PRI_MIN_TIMESHARE && 910 td->td_base_pri <= PRI_MAX_TIMESHARE) 911 base_pri = td->td_user_pri; 912 else 913 base_pri = td->td_base_pri; 914 if (prio >= base_pri) { 915 td->td_flags &= ~TDF_BORROWING; 916 sched_prio(td, base_pri); 917 } else 918 sched_lend_prio(td, prio); 919 } 920 921 void 922 sched_prio(struct thread *td, u_char prio) 923 { 924 u_char oldprio; 925 926 /* First, update the base priority. */ 927 td->td_base_pri = prio; 928 929 /* 930 * If the thread is borrowing another thread's priority, don't ever 931 * lower the priority. 932 */ 933 if (td->td_flags & TDF_BORROWING && td->td_priority < prio) 934 return; 935 936 /* Change the real priority. */ 937 oldprio = td->td_priority; 938 sched_priority(td, prio); 939 940 /* 941 * If the thread is on a turnstile, then let the turnstile update 942 * its state. 943 */ 944 if (TD_ON_LOCK(td) && oldprio != prio) 945 turnstile_adjust(td, oldprio); 946 } 947 948 void 949 sched_ithread_prio(struct thread *td, u_char prio) 950 { 951 THREAD_LOCK_ASSERT(td, MA_OWNED); 952 MPASS(td->td_pri_class == PRI_ITHD); 953 td->td_base_ithread_pri = prio; 954 sched_prio(td, prio); 955 } 956 957 void 958 sched_user_prio(struct thread *td, u_char prio) 959 { 960 961 THREAD_LOCK_ASSERT(td, MA_OWNED); 962 td->td_base_user_pri = prio; 963 if (td->td_lend_user_pri <= prio) 964 return; 965 td->td_user_pri = prio; 966 } 967 968 void 969 sched_lend_user_prio(struct thread *td, u_char prio) 970 { 971 972 THREAD_LOCK_ASSERT(td, MA_OWNED); 973 td->td_lend_user_pri = prio; 974 td->td_user_pri = min(prio, td->td_base_user_pri); 975 if (td->td_priority > td->td_user_pri) 976 sched_prio(td, td->td_user_pri); 977 else if (td->td_priority != td->td_user_pri) 978 ast_sched_locked(td, TDA_SCHED); 979 } 980 981 /* 982 * Like the above but first check if there is anything to do. 983 */ 984 void 985 sched_lend_user_prio_cond(struct thread *td, u_char prio) 986 { 987 988 if (td->td_lend_user_pri == prio) 989 return; 990 991 thread_lock(td); 992 sched_lend_user_prio(td, prio); 993 thread_unlock(td); 994 } 995 996 void 997 sched_sleep(struct thread *td, int pri) 998 { 999 1000 THREAD_LOCK_ASSERT(td, MA_OWNED); 1001 td->td_slptick = ticks; 1002 td_get_sched(td)->ts_slptime = 0; 1003 if (pri != 0 && PRI_BASE(td->td_pri_class) == PRI_TIMESHARE) 1004 sched_prio(td, pri); 1005 } 1006 1007 void 1008 sched_switch(struct thread *td, int flags) 1009 { 1010 struct thread *newtd; 1011 struct mtx *tmtx; 1012 int preempted; 1013 1014 tmtx = &sched_lock; 1015 1016 THREAD_LOCK_ASSERT(td, MA_OWNED); 1017 1018 td->td_lastcpu = td->td_oncpu; 1019 preempted = (td->td_flags & TDF_SLICEEND) == 0 && 1020 (flags & SW_PREEMPT) != 0; 1021 td->td_flags &= ~TDF_SLICEEND; 1022 ast_unsched_locked(td, TDA_SCHED); 1023 td->td_owepreempt = 0; 1024 td->td_oncpu = NOCPU; 1025 1026 /* 1027 * At the last moment, if this thread is still marked RUNNING, 1028 * then put it back on the run queue as it has not been suspended 1029 * or stopped or any thing else similar. We never put the idle 1030 * threads on the run queue, however. 1031 */ 1032 if (td->td_flags & TDF_IDLETD) { 1033 TD_SET_CAN_RUN(td); 1034 #ifdef SMP 1035 CPU_CLR(PCPU_GET(cpuid), &idle_cpus_mask); 1036 #endif 1037 } else { 1038 if (TD_IS_RUNNING(td)) { 1039 /* Put us back on the run queue. */ 1040 sched_add(td, SRQ_HOLDTD | SRQ_OURSELF | SRQ_YIELDING | 1041 (preempted ? SRQ_PREEMPTED : 0)); 1042 } 1043 } 1044 1045 /* 1046 * Switch to the sched lock to fix things up and pick 1047 * a new thread. Block the td_lock in order to avoid 1048 * breaking the critical path. 1049 */ 1050 if (td->td_lock != &sched_lock) { 1051 mtx_lock_spin(&sched_lock); 1052 tmtx = thread_lock_block(td); 1053 mtx_unlock_spin(tmtx); 1054 } 1055 1056 if ((td->td_flags & TDF_NOLOAD) == 0) 1057 sched_load_rem(); 1058 1059 newtd = choosethread(); 1060 MPASS(newtd->td_lock == &sched_lock); 1061 1062 #if (KTR_COMPILE & KTR_SCHED) != 0 1063 if (TD_IS_IDLETHREAD(td)) 1064 KTR_STATE1(KTR_SCHED, "thread", sched_tdname(td), "idle", 1065 "prio:%d", td->td_priority); 1066 else 1067 KTR_STATE3(KTR_SCHED, "thread", sched_tdname(td), KTDSTATE(td), 1068 "prio:%d", td->td_priority, "wmesg:\"%s\"", td->td_wmesg, 1069 "lockname:\"%s\"", td->td_lockname); 1070 #endif 1071 1072 if (td != newtd) { 1073 #ifdef HWPMC_HOOKS 1074 if (PMC_PROC_IS_USING_PMCS(td->td_proc)) 1075 PMC_SWITCH_CONTEXT(td, PMC_FN_CSW_OUT); 1076 #endif 1077 1078 SDT_PROBE2(sched, , , off__cpu, newtd, newtd->td_proc); 1079 1080 /* I feel sleepy */ 1081 lock_profile_release_lock(&sched_lock.lock_object, true); 1082 #ifdef KDTRACE_HOOKS 1083 /* 1084 * If DTrace has set the active vtime enum to anything 1085 * other than INACTIVE (0), then it should have set the 1086 * function to call. 1087 */ 1088 if (dtrace_vtime_active) 1089 (*dtrace_vtime_switch_func)(newtd); 1090 #endif 1091 1092 cpu_switch(td, newtd, tmtx); 1093 lock_profile_obtain_lock_success(&sched_lock.lock_object, true, 1094 0, 0, __FILE__, __LINE__); 1095 /* 1096 * Where am I? What year is it? 1097 * We are in the same thread that went to sleep above, 1098 * but any amount of time may have passed. All our context 1099 * will still be available as will local variables. 1100 * PCPU values however may have changed as we may have 1101 * changed CPU so don't trust cached values of them. 1102 * New threads will go to fork_exit() instead of here 1103 * so if you change things here you may need to change 1104 * things there too. 1105 * 1106 * If the thread above was exiting it will never wake 1107 * up again here, so either it has saved everything it 1108 * needed to, or the thread_wait() or wait() will 1109 * need to reap it. 1110 */ 1111 1112 SDT_PROBE0(sched, , , on__cpu); 1113 #ifdef HWPMC_HOOKS 1114 if (PMC_PROC_IS_USING_PMCS(td->td_proc)) 1115 PMC_SWITCH_CONTEXT(td, PMC_FN_CSW_IN); 1116 #endif 1117 } else { 1118 td->td_lock = &sched_lock; 1119 SDT_PROBE0(sched, , , remain__cpu); 1120 } 1121 1122 KTR_STATE1(KTR_SCHED, "thread", sched_tdname(td), "running", 1123 "prio:%d", td->td_priority); 1124 1125 #ifdef SMP 1126 if (td->td_flags & TDF_IDLETD) 1127 CPU_SET(PCPU_GET(cpuid), &idle_cpus_mask); 1128 #endif 1129 sched_lock.mtx_lock = (uintptr_t)td; 1130 td->td_oncpu = PCPU_GET(cpuid); 1131 spinlock_enter(); 1132 mtx_unlock_spin(&sched_lock); 1133 } 1134 1135 void 1136 sched_wakeup(struct thread *td, int srqflags) 1137 { 1138 struct td_sched *ts; 1139 1140 THREAD_LOCK_ASSERT(td, MA_OWNED); 1141 ts = td_get_sched(td); 1142 if (ts->ts_slptime > 1) { 1143 updatepri(td); 1144 resetpriority(td); 1145 } 1146 td->td_slptick = 0; 1147 ts->ts_slptime = 0; 1148 ts->ts_slice = sched_slice; 1149 1150 /* 1151 * When resuming an idle ithread, restore its base ithread 1152 * priority. 1153 */ 1154 if (PRI_BASE(td->td_pri_class) == PRI_ITHD && 1155 td->td_base_pri != td->td_base_ithread_pri) 1156 sched_prio(td, td->td_base_ithread_pri); 1157 1158 sched_add(td, srqflags); 1159 } 1160 1161 #ifdef SMP 1162 static int 1163 forward_wakeup(int cpunum) 1164 { 1165 struct pcpu *pc; 1166 cpuset_t dontuse, map, map2; 1167 u_int id, me; 1168 int iscpuset; 1169 1170 mtx_assert(&sched_lock, MA_OWNED); 1171 1172 CTR0(KTR_RUNQ, "forward_wakeup()"); 1173 1174 if ((!forward_wakeup_enabled) || 1175 (forward_wakeup_use_mask == 0 && forward_wakeup_use_loop == 0)) 1176 return (0); 1177 if (!smp_started || KERNEL_PANICKED()) 1178 return (0); 1179 1180 forward_wakeups_requested++; 1181 1182 /* 1183 * Check the idle mask we received against what we calculated 1184 * before in the old version. 1185 */ 1186 me = PCPU_GET(cpuid); 1187 1188 /* Don't bother if we should be doing it ourself. */ 1189 if (CPU_ISSET(me, &idle_cpus_mask) && 1190 (cpunum == NOCPU || me == cpunum)) 1191 return (0); 1192 1193 CPU_SETOF(me, &dontuse); 1194 CPU_OR(&dontuse, &dontuse, &stopped_cpus); 1195 CPU_OR(&dontuse, &dontuse, &hlt_cpus_mask); 1196 CPU_ZERO(&map2); 1197 if (forward_wakeup_use_loop) { 1198 STAILQ_FOREACH(pc, &cpuhead, pc_allcpu) { 1199 id = pc->pc_cpuid; 1200 if (!CPU_ISSET(id, &dontuse) && 1201 pc->pc_curthread == pc->pc_idlethread) { 1202 CPU_SET(id, &map2); 1203 } 1204 } 1205 } 1206 1207 if (forward_wakeup_use_mask) { 1208 map = idle_cpus_mask; 1209 CPU_ANDNOT(&map, &map, &dontuse); 1210 1211 /* If they are both on, compare and use loop if different. */ 1212 if (forward_wakeup_use_loop) { 1213 if (CPU_CMP(&map, &map2)) { 1214 printf("map != map2, loop method preferred\n"); 1215 map = map2; 1216 } 1217 } 1218 } else { 1219 map = map2; 1220 } 1221 1222 /* If we only allow a specific CPU, then mask off all the others. */ 1223 if (cpunum != NOCPU) { 1224 KASSERT((cpunum <= mp_maxcpus),("forward_wakeup: bad cpunum.")); 1225 iscpuset = CPU_ISSET(cpunum, &map); 1226 if (iscpuset == 0) 1227 CPU_ZERO(&map); 1228 else 1229 CPU_SETOF(cpunum, &map); 1230 } 1231 if (!CPU_EMPTY(&map)) { 1232 forward_wakeups_delivered++; 1233 STAILQ_FOREACH(pc, &cpuhead, pc_allcpu) { 1234 id = pc->pc_cpuid; 1235 if (!CPU_ISSET(id, &map)) 1236 continue; 1237 if (cpu_idle_wakeup(pc->pc_cpuid)) 1238 CPU_CLR(id, &map); 1239 } 1240 if (!CPU_EMPTY(&map)) 1241 ipi_selected(map, IPI_AST); 1242 return (1); 1243 } 1244 if (cpunum == NOCPU) 1245 printf("forward_wakeup: Idle processor not found\n"); 1246 return (0); 1247 } 1248 1249 static void 1250 kick_other_cpu(int pri, int cpuid) 1251 { 1252 struct pcpu *pcpu; 1253 int cpri; 1254 1255 pcpu = pcpu_find(cpuid); 1256 if (CPU_ISSET(cpuid, &idle_cpus_mask)) { 1257 forward_wakeups_delivered++; 1258 if (!cpu_idle_wakeup(cpuid)) 1259 ipi_cpu(cpuid, IPI_AST); 1260 return; 1261 } 1262 1263 cpri = pcpu->pc_curthread->td_priority; 1264 if (pri >= cpri) 1265 return; 1266 1267 #if defined(IPI_PREEMPTION) && defined(PREEMPTION) 1268 #if !defined(FULL_PREEMPTION) 1269 if (pri <= PRI_MAX_ITHD) 1270 #endif /* ! FULL_PREEMPTION */ 1271 { 1272 ipi_cpu(cpuid, IPI_PREEMPT); 1273 return; 1274 } 1275 #endif /* defined(IPI_PREEMPTION) && defined(PREEMPTION) */ 1276 1277 if (pcpu->pc_curthread->td_lock == &sched_lock) { 1278 ast_sched_locked(pcpu->pc_curthread, TDA_SCHED); 1279 ipi_cpu(cpuid, IPI_AST); 1280 } 1281 } 1282 #endif /* SMP */ 1283 1284 #ifdef SMP 1285 static int 1286 sched_pickcpu(struct thread *td) 1287 { 1288 int best, cpu; 1289 1290 mtx_assert(&sched_lock, MA_OWNED); 1291 1292 if (td->td_lastcpu != NOCPU && THREAD_CAN_SCHED(td, td->td_lastcpu)) 1293 best = td->td_lastcpu; 1294 else 1295 best = NOCPU; 1296 CPU_FOREACH(cpu) { 1297 if (!THREAD_CAN_SCHED(td, cpu)) 1298 continue; 1299 1300 if (best == NOCPU) 1301 best = cpu; 1302 else if (runq_length[cpu] < runq_length[best]) 1303 best = cpu; 1304 } 1305 KASSERT(best != NOCPU, ("no valid CPUs")); 1306 1307 return (best); 1308 } 1309 #endif 1310 1311 void 1312 sched_add(struct thread *td, int flags) 1313 #ifdef SMP 1314 { 1315 cpuset_t tidlemsk; 1316 struct td_sched *ts; 1317 u_int cpu, cpuid; 1318 int forwarded = 0; 1319 int single_cpu = 0; 1320 1321 ts = td_get_sched(td); 1322 THREAD_LOCK_ASSERT(td, MA_OWNED); 1323 KASSERT((td->td_inhibitors == 0), 1324 ("sched_add: trying to run inhibited thread")); 1325 KASSERT((TD_CAN_RUN(td) || TD_IS_RUNNING(td)), 1326 ("sched_add: bad thread state")); 1327 KASSERT(td->td_flags & TDF_INMEM, 1328 ("sched_add: thread swapped out")); 1329 1330 KTR_STATE2(KTR_SCHED, "thread", sched_tdname(td), "runq add", 1331 "prio:%d", td->td_priority, KTR_ATTR_LINKED, 1332 sched_tdname(curthread)); 1333 KTR_POINT1(KTR_SCHED, "thread", sched_tdname(curthread), "wokeup", 1334 KTR_ATTR_LINKED, sched_tdname(td)); 1335 SDT_PROBE4(sched, , , enqueue, td, td->td_proc, NULL, 1336 flags & SRQ_PREEMPTED); 1337 1338 /* 1339 * Now that the thread is moving to the run-queue, set the lock 1340 * to the scheduler's lock. 1341 */ 1342 if (td->td_lock != &sched_lock) { 1343 mtx_lock_spin(&sched_lock); 1344 if ((flags & SRQ_HOLD) != 0) 1345 td->td_lock = &sched_lock; 1346 else 1347 thread_lock_set(td, &sched_lock); 1348 } 1349 TD_SET_RUNQ(td); 1350 1351 /* 1352 * If SMP is started and the thread is pinned or otherwise limited to 1353 * a specific set of CPUs, queue the thread to a per-CPU run queue. 1354 * Otherwise, queue the thread to the global run queue. 1355 * 1356 * If SMP has not yet been started we must use the global run queue 1357 * as per-CPU state may not be initialized yet and we may crash if we 1358 * try to access the per-CPU run queues. 1359 */ 1360 if (smp_started && (td->td_pinned != 0 || td->td_flags & TDF_BOUND || 1361 ts->ts_flags & TSF_AFFINITY)) { 1362 if (td->td_pinned != 0) 1363 cpu = td->td_lastcpu; 1364 else if (td->td_flags & TDF_BOUND) { 1365 /* Find CPU from bound runq. */ 1366 KASSERT(SKE_RUNQ_PCPU(ts), 1367 ("sched_add: bound td_sched not on cpu runq")); 1368 cpu = ts->ts_runq - &runq_pcpu[0]; 1369 } else 1370 /* Find a valid CPU for our cpuset */ 1371 cpu = sched_pickcpu(td); 1372 ts->ts_runq = &runq_pcpu[cpu]; 1373 single_cpu = 1; 1374 CTR3(KTR_RUNQ, 1375 "sched_add: Put td_sched:%p(td:%p) on cpu%d runq", ts, td, 1376 cpu); 1377 } else { 1378 CTR2(KTR_RUNQ, 1379 "sched_add: adding td_sched:%p (td:%p) to gbl runq", ts, 1380 td); 1381 cpu = NOCPU; 1382 ts->ts_runq = &runq; 1383 } 1384 1385 if ((td->td_flags & TDF_NOLOAD) == 0) 1386 sched_load_add(); 1387 runq_add(ts->ts_runq, td, flags); 1388 if (cpu != NOCPU) 1389 runq_length[cpu]++; 1390 1391 cpuid = PCPU_GET(cpuid); 1392 if (single_cpu && cpu != cpuid) { 1393 kick_other_cpu(td->td_priority, cpu); 1394 } else { 1395 if (!single_cpu) { 1396 tidlemsk = idle_cpus_mask; 1397 CPU_ANDNOT(&tidlemsk, &tidlemsk, &hlt_cpus_mask); 1398 CPU_CLR(cpuid, &tidlemsk); 1399 1400 if (!CPU_ISSET(cpuid, &idle_cpus_mask) && 1401 ((flags & SRQ_INTR) == 0) && 1402 !CPU_EMPTY(&tidlemsk)) 1403 forwarded = forward_wakeup(cpu); 1404 } 1405 1406 if (!forwarded) { 1407 if (!maybe_preempt(td)) 1408 maybe_resched(td); 1409 } 1410 } 1411 if ((flags & SRQ_HOLDTD) == 0) 1412 thread_unlock(td); 1413 } 1414 #else /* SMP */ 1415 { 1416 struct td_sched *ts; 1417 1418 ts = td_get_sched(td); 1419 THREAD_LOCK_ASSERT(td, MA_OWNED); 1420 KASSERT((td->td_inhibitors == 0), 1421 ("sched_add: trying to run inhibited thread")); 1422 KASSERT((TD_CAN_RUN(td) || TD_IS_RUNNING(td)), 1423 ("sched_add: bad thread state")); 1424 KASSERT(td->td_flags & TDF_INMEM, 1425 ("sched_add: thread swapped out")); 1426 KTR_STATE2(KTR_SCHED, "thread", sched_tdname(td), "runq add", 1427 "prio:%d", td->td_priority, KTR_ATTR_LINKED, 1428 sched_tdname(curthread)); 1429 KTR_POINT1(KTR_SCHED, "thread", sched_tdname(curthread), "wokeup", 1430 KTR_ATTR_LINKED, sched_tdname(td)); 1431 SDT_PROBE4(sched, , , enqueue, td, td->td_proc, NULL, 1432 flags & SRQ_PREEMPTED); 1433 1434 /* 1435 * Now that the thread is moving to the run-queue, set the lock 1436 * to the scheduler's lock. 1437 */ 1438 if (td->td_lock != &sched_lock) { 1439 mtx_lock_spin(&sched_lock); 1440 if ((flags & SRQ_HOLD) != 0) 1441 td->td_lock = &sched_lock; 1442 else 1443 thread_lock_set(td, &sched_lock); 1444 } 1445 TD_SET_RUNQ(td); 1446 CTR2(KTR_RUNQ, "sched_add: adding td_sched:%p (td:%p) to runq", ts, td); 1447 ts->ts_runq = &runq; 1448 1449 if ((td->td_flags & TDF_NOLOAD) == 0) 1450 sched_load_add(); 1451 runq_add(ts->ts_runq, td, flags); 1452 if (!maybe_preempt(td)) 1453 maybe_resched(td); 1454 if ((flags & SRQ_HOLDTD) == 0) 1455 thread_unlock(td); 1456 } 1457 #endif /* SMP */ 1458 1459 void 1460 sched_rem(struct thread *td) 1461 { 1462 struct td_sched *ts; 1463 1464 ts = td_get_sched(td); 1465 KASSERT(td->td_flags & TDF_INMEM, 1466 ("sched_rem: thread swapped out")); 1467 KASSERT(TD_ON_RUNQ(td), 1468 ("sched_rem: thread not on run queue")); 1469 mtx_assert(&sched_lock, MA_OWNED); 1470 KTR_STATE2(KTR_SCHED, "thread", sched_tdname(td), "runq rem", 1471 "prio:%d", td->td_priority, KTR_ATTR_LINKED, 1472 sched_tdname(curthread)); 1473 SDT_PROBE3(sched, , , dequeue, td, td->td_proc, NULL); 1474 1475 if ((td->td_flags & TDF_NOLOAD) == 0) 1476 sched_load_rem(); 1477 #ifdef SMP 1478 if (ts->ts_runq != &runq) 1479 runq_length[ts->ts_runq - runq_pcpu]--; 1480 #endif 1481 runq_remove(ts->ts_runq, td); 1482 TD_SET_CAN_RUN(td); 1483 } 1484 1485 /* 1486 * Select threads to run. Note that running threads still consume a 1487 * slot. 1488 */ 1489 struct thread * 1490 sched_choose(void) 1491 { 1492 struct thread *td; 1493 struct runq *rq; 1494 1495 mtx_assert(&sched_lock, MA_OWNED); 1496 #ifdef SMP 1497 struct thread *tdcpu; 1498 1499 rq = &runq; 1500 td = runq_choose_fuzz(&runq, runq_fuzz); 1501 tdcpu = runq_choose(&runq_pcpu[PCPU_GET(cpuid)]); 1502 1503 if (td == NULL || 1504 (tdcpu != NULL && 1505 tdcpu->td_priority < td->td_priority)) { 1506 CTR2(KTR_RUNQ, "choosing td %p from pcpu runq %d", tdcpu, 1507 PCPU_GET(cpuid)); 1508 td = tdcpu; 1509 rq = &runq_pcpu[PCPU_GET(cpuid)]; 1510 } else { 1511 CTR1(KTR_RUNQ, "choosing td_sched %p from main runq", td); 1512 } 1513 1514 #else 1515 rq = &runq; 1516 td = runq_choose(&runq); 1517 #endif 1518 1519 if (td) { 1520 #ifdef SMP 1521 if (td == tdcpu) 1522 runq_length[PCPU_GET(cpuid)]--; 1523 #endif 1524 runq_remove(rq, td); 1525 td->td_flags |= TDF_DIDRUN; 1526 1527 KASSERT(td->td_flags & TDF_INMEM, 1528 ("sched_choose: thread swapped out")); 1529 return (td); 1530 } 1531 return (PCPU_GET(idlethread)); 1532 } 1533 1534 void 1535 sched_preempt(struct thread *td) 1536 { 1537 int flags; 1538 1539 SDT_PROBE2(sched, , , surrender, td, td->td_proc); 1540 if (td->td_critnest > 1) { 1541 td->td_owepreempt = 1; 1542 } else { 1543 thread_lock(td); 1544 flags = SW_INVOL | SW_PREEMPT; 1545 flags |= TD_IS_IDLETHREAD(td) ? SWT_REMOTEWAKEIDLE : 1546 SWT_REMOTEPREEMPT; 1547 mi_switch(flags); 1548 } 1549 } 1550 1551 void 1552 sched_userret_slowpath(struct thread *td) 1553 { 1554 1555 thread_lock(td); 1556 td->td_priority = td->td_user_pri; 1557 td->td_base_pri = td->td_user_pri; 1558 thread_unlock(td); 1559 } 1560 1561 void 1562 sched_bind(struct thread *td, int cpu) 1563 { 1564 #ifdef SMP 1565 struct td_sched *ts = td_get_sched(td); 1566 #endif 1567 1568 THREAD_LOCK_ASSERT(td, MA_OWNED|MA_NOTRECURSED); 1569 KASSERT(td == curthread, ("sched_bind: can only bind curthread")); 1570 1571 td->td_flags |= TDF_BOUND; 1572 #ifdef SMP 1573 ts->ts_runq = &runq_pcpu[cpu]; 1574 if (PCPU_GET(cpuid) == cpu) 1575 return; 1576 1577 mi_switch(SW_VOL | SWT_BIND); 1578 thread_lock(td); 1579 #endif 1580 } 1581 1582 void 1583 sched_unbind(struct thread* td) 1584 { 1585 THREAD_LOCK_ASSERT(td, MA_OWNED); 1586 KASSERT(td == curthread, ("sched_unbind: can only bind curthread")); 1587 td->td_flags &= ~TDF_BOUND; 1588 } 1589 1590 int 1591 sched_is_bound(struct thread *td) 1592 { 1593 THREAD_LOCK_ASSERT(td, MA_OWNED); 1594 return (td->td_flags & TDF_BOUND); 1595 } 1596 1597 void 1598 sched_relinquish(struct thread *td) 1599 { 1600 thread_lock(td); 1601 mi_switch(SW_VOL | SWT_RELINQUISH); 1602 } 1603 1604 int 1605 sched_load(void) 1606 { 1607 return (sched_tdcnt); 1608 } 1609 1610 int 1611 sched_sizeof_proc(void) 1612 { 1613 return (sizeof(struct proc)); 1614 } 1615 1616 int 1617 sched_sizeof_thread(void) 1618 { 1619 return (sizeof(struct thread) + sizeof(struct td_sched)); 1620 } 1621 1622 fixpt_t 1623 sched_pctcpu(struct thread *td) 1624 { 1625 struct td_sched *ts; 1626 1627 THREAD_LOCK_ASSERT(td, MA_OWNED); 1628 ts = td_get_sched(td); 1629 return (ts->ts_pctcpu); 1630 } 1631 1632 #ifdef RACCT 1633 /* 1634 * Calculates the contribution to the thread cpu usage for the latest 1635 * (unfinished) second. 1636 */ 1637 fixpt_t 1638 sched_pctcpu_delta(struct thread *td) 1639 { 1640 struct td_sched *ts; 1641 fixpt_t delta; 1642 int realstathz; 1643 1644 THREAD_LOCK_ASSERT(td, MA_OWNED); 1645 ts = td_get_sched(td); 1646 delta = 0; 1647 realstathz = stathz ? stathz : hz; 1648 if (ts->ts_cpticks != 0) { 1649 #if (FSHIFT >= CCPU_SHIFT) 1650 delta = (realstathz == 100) 1651 ? ((fixpt_t) ts->ts_cpticks) << 1652 (FSHIFT - CCPU_SHIFT) : 1653 100 * (((fixpt_t) ts->ts_cpticks) 1654 << (FSHIFT - CCPU_SHIFT)) / realstathz; 1655 #else 1656 delta = ((FSCALE - ccpu) * 1657 (ts->ts_cpticks * 1658 FSCALE / realstathz)) >> FSHIFT; 1659 #endif 1660 } 1661 1662 return (delta); 1663 } 1664 #endif 1665 1666 u_int 1667 sched_estcpu(struct thread *td) 1668 { 1669 1670 return (td_get_sched(td)->ts_estcpu); 1671 } 1672 1673 /* 1674 * The actual idle process. 1675 */ 1676 void 1677 sched_idletd(void *dummy) 1678 { 1679 struct pcpuidlestat *stat; 1680 1681 THREAD_NO_SLEEPING(); 1682 stat = DPCPU_PTR(idlestat); 1683 for (;;) { 1684 mtx_assert(&Giant, MA_NOTOWNED); 1685 1686 while (!sched_runnable()) { 1687 cpu_idle(stat->idlecalls + stat->oldidlecalls > 64); 1688 stat->idlecalls++; 1689 } 1690 1691 mtx_lock_spin(&sched_lock); 1692 mi_switch(SW_VOL | SWT_IDLE); 1693 } 1694 } 1695 1696 static void 1697 sched_throw_tail(struct thread *td) 1698 { 1699 1700 mtx_assert(&sched_lock, MA_OWNED); 1701 KASSERT(curthread->td_md.md_spinlock_count == 1, ("invalid count")); 1702 cpu_throw(td, choosethread()); /* doesn't return */ 1703 } 1704 1705 /* 1706 * A CPU is entering for the first time. 1707 */ 1708 void 1709 sched_ap_entry(void) 1710 { 1711 1712 /* 1713 * Correct spinlock nesting. The idle thread context that we are 1714 * borrowing was created so that it would start out with a single 1715 * spin lock (sched_lock) held in fork_trampoline(). Since we've 1716 * explicitly acquired locks in this function, the nesting count 1717 * is now 2 rather than 1. Since we are nested, calling 1718 * spinlock_exit() will simply adjust the counts without allowing 1719 * spin lock using code to interrupt us. 1720 */ 1721 mtx_lock_spin(&sched_lock); 1722 spinlock_exit(); 1723 PCPU_SET(switchtime, cpu_ticks()); 1724 PCPU_SET(switchticks, ticks); 1725 1726 sched_throw_tail(NULL); 1727 } 1728 1729 /* 1730 * A thread is exiting. 1731 */ 1732 void 1733 sched_throw(struct thread *td) 1734 { 1735 1736 MPASS(td != NULL); 1737 MPASS(td->td_lock == &sched_lock); 1738 1739 lock_profile_release_lock(&sched_lock.lock_object, true); 1740 td->td_lastcpu = td->td_oncpu; 1741 td->td_oncpu = NOCPU; 1742 1743 sched_throw_tail(td); 1744 } 1745 1746 void 1747 sched_fork_exit(struct thread *td) 1748 { 1749 1750 /* 1751 * Finish setting up thread glue so that it begins execution in a 1752 * non-nested critical section with sched_lock held but not recursed. 1753 */ 1754 td->td_oncpu = PCPU_GET(cpuid); 1755 sched_lock.mtx_lock = (uintptr_t)td; 1756 lock_profile_obtain_lock_success(&sched_lock.lock_object, true, 1757 0, 0, __FILE__, __LINE__); 1758 THREAD_LOCK_ASSERT(td, MA_OWNED | MA_NOTRECURSED); 1759 1760 KTR_STATE1(KTR_SCHED, "thread", sched_tdname(td), "running", 1761 "prio:%d", td->td_priority); 1762 SDT_PROBE0(sched, , , on__cpu); 1763 } 1764 1765 char * 1766 sched_tdname(struct thread *td) 1767 { 1768 #ifdef KTR 1769 struct td_sched *ts; 1770 1771 ts = td_get_sched(td); 1772 if (ts->ts_name[0] == '\0') 1773 snprintf(ts->ts_name, sizeof(ts->ts_name), 1774 "%s tid %d", td->td_name, td->td_tid); 1775 return (ts->ts_name); 1776 #else 1777 return (td->td_name); 1778 #endif 1779 } 1780 1781 #ifdef KTR 1782 void 1783 sched_clear_tdname(struct thread *td) 1784 { 1785 struct td_sched *ts; 1786 1787 ts = td_get_sched(td); 1788 ts->ts_name[0] = '\0'; 1789 } 1790 #endif 1791 1792 void 1793 sched_affinity(struct thread *td) 1794 { 1795 #ifdef SMP 1796 struct td_sched *ts; 1797 int cpu; 1798 1799 THREAD_LOCK_ASSERT(td, MA_OWNED); 1800 1801 /* 1802 * Set the TSF_AFFINITY flag if there is at least one CPU this 1803 * thread can't run on. 1804 */ 1805 ts = td_get_sched(td); 1806 ts->ts_flags &= ~TSF_AFFINITY; 1807 CPU_FOREACH(cpu) { 1808 if (!THREAD_CAN_SCHED(td, cpu)) { 1809 ts->ts_flags |= TSF_AFFINITY; 1810 break; 1811 } 1812 } 1813 1814 /* 1815 * If this thread can run on all CPUs, nothing else to do. 1816 */ 1817 if (!(ts->ts_flags & TSF_AFFINITY)) 1818 return; 1819 1820 /* Pinned threads and bound threads should be left alone. */ 1821 if (td->td_pinned != 0 || td->td_flags & TDF_BOUND) 1822 return; 1823 1824 switch (TD_GET_STATE(td)) { 1825 case TDS_RUNQ: 1826 /* 1827 * If we are on a per-CPU runqueue that is in the set, 1828 * then nothing needs to be done. 1829 */ 1830 if (ts->ts_runq != &runq && 1831 THREAD_CAN_SCHED(td, ts->ts_runq - runq_pcpu)) 1832 return; 1833 1834 /* Put this thread on a valid per-CPU runqueue. */ 1835 sched_rem(td); 1836 sched_add(td, SRQ_HOLDTD | SRQ_BORING); 1837 break; 1838 case TDS_RUNNING: 1839 /* 1840 * See if our current CPU is in the set. If not, force a 1841 * context switch. 1842 */ 1843 if (THREAD_CAN_SCHED(td, td->td_oncpu)) 1844 return; 1845 1846 ast_sched_locked(td, TDA_SCHED); 1847 if (td != curthread) 1848 ipi_cpu(cpu, IPI_AST); 1849 break; 1850 default: 1851 break; 1852 } 1853 #endif 1854 } 1855