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