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_hwt_hooks.h" 40 #include "opt_sched.h" 41 42 #include <sys/param.h> 43 #include <sys/systm.h> 44 #include <sys/cpuset.h> 45 #include <sys/kernel.h> 46 #include <sys/ktr.h> 47 #include <sys/lock.h> 48 #include <sys/kthread.h> 49 #include <sys/mutex.h> 50 #include <sys/proc.h> 51 #include <sys/resourcevar.h> 52 #include <sys/runq.h> 53 #include <sys/sched.h> 54 #include <sys/sdt.h> 55 #include <sys/smp.h> 56 #include <sys/sysctl.h> 57 #include <sys/sx.h> 58 #include <sys/turnstile.h> 59 #include <sys/umtxvar.h> 60 #include <machine/pcb.h> 61 #include <machine/smp.h> 62 63 #ifdef HWPMC_HOOKS 64 #include <sys/pmckern.h> 65 #endif 66 67 #ifdef HWT_HOOKS 68 #include <dev/hwt/hwt_hook.h> 69 #endif 70 71 #ifdef KDTRACE_HOOKS 72 #include <sys/dtrace_bsd.h> 73 int __read_mostly dtrace_vtime_active; 74 dtrace_vtime_switch_func_t dtrace_vtime_switch_func; 75 #endif 76 77 /* 78 * INVERSE_ESTCPU_WEIGHT is only suitable for statclock() frequencies in 79 * the range 100-256 Hz (approximately). 80 */ 81 #ifdef SMP 82 #define INVERSE_ESTCPU_WEIGHT (8 * smp_cpus) 83 #else 84 #define INVERSE_ESTCPU_WEIGHT 8 /* 1 / (priorities per estcpu level). */ 85 #endif 86 #define NICE_WEIGHT 1 /* Priorities per nice level. */ 87 #define ESTCPULIM(e) \ 88 min((e), INVERSE_ESTCPU_WEIGHT * \ 89 (NICE_WEIGHT * (PRIO_MAX - PRIO_MIN) + \ 90 PRI_MAX_TIMESHARE - PRI_MIN_TIMESHARE) \ 91 + INVERSE_ESTCPU_WEIGHT - 1) 92 93 #define TS_NAME_LEN (MAXCOMLEN + sizeof(" td ") + sizeof(__XSTRING(UINT_MAX))) 94 95 /* 96 * The schedulable entity that runs a context. 97 * This is an extension to the thread structure and is tailored to 98 * the requirements of this scheduler. 99 * All fields are protected by the scheduler lock. 100 */ 101 struct td_sched { 102 fixpt_t ts_pctcpu; /* %cpu during p_swtime. */ 103 u_int ts_estcpu; /* Estimated cpu utilization. */ 104 int ts_cpticks; /* Ticks of cpu time. */ 105 int ts_slptime; /* Seconds !RUNNING. */ 106 int ts_slice; /* Remaining part of time slice. */ 107 int ts_flags; 108 struct runq *ts_runq; /* runq the thread is currently on */ 109 #ifdef KTR 110 char ts_name[TS_NAME_LEN]; 111 #endif 112 }; 113 114 /* flags kept in td_flags */ 115 #define TDF_DIDRUN TDF_SCHED0 /* thread actually ran. */ 116 #define TDF_BOUND TDF_SCHED1 /* Bound to one CPU. */ 117 #define TDF_SLICEEND TDF_SCHED2 /* Thread time slice is over. */ 118 119 /* flags kept in ts_flags */ 120 #define TSF_AFFINITY 0x0001 /* Has a non-"full" CPU set. */ 121 122 #define SKE_RUNQ_PCPU(ts) \ 123 ((ts)->ts_runq != 0 && (ts)->ts_runq != &runq) 124 125 #define THREAD_CAN_SCHED(td, cpu) \ 126 CPU_ISSET((cpu), &(td)->td_cpuset->cs_mask) 127 128 _Static_assert(sizeof(struct thread) + sizeof(struct td_sched) <= 129 sizeof(struct thread0_storage), 130 "increase struct thread0_storage.t0st_sched size"); 131 132 static struct mtx sched_lock; 133 134 static int realstathz = 127; /* stathz is sometimes 0 and run off of hz. */ 135 static int sched_tdcnt; /* Total runnable threads in the system. */ 136 static int sched_slice = 12; /* Thread run time before rescheduling. */ 137 138 static void setup_runqs(void); 139 static void schedcpu(void); 140 static void schedcpu_thread(void); 141 static void sched_priority(struct thread *td, u_char prio); 142 static void sched_setup(void *dummy); 143 static void maybe_resched(struct thread *td); 144 static void updatepri(struct thread *td); 145 static void resetpriority(struct thread *td); 146 static void resetpriority_thread(struct thread *td); 147 #ifdef SMP 148 static int sched_pickcpu(struct thread *td); 149 static int forward_wakeup(int cpunum); 150 static void kick_other_cpu(int pri, int cpuid); 151 #endif 152 153 static struct kproc_desc sched_kp = { 154 "schedcpu", 155 schedcpu_thread, 156 NULL 157 }; 158 SYSINIT(schedcpu, SI_SUB_LAST, SI_ORDER_FIRST, kproc_start, 159 &sched_kp); 160 SYSINIT(sched_setup, SI_SUB_RUN_QUEUE, SI_ORDER_FIRST, sched_setup, NULL); 161 162 static void sched_initticks(void *dummy); 163 SYSINIT(sched_initticks, SI_SUB_CLOCKS, SI_ORDER_THIRD, sched_initticks, 164 NULL); 165 166 /* 167 * Global run queue. 168 */ 169 static struct runq runq; 170 171 #ifdef SMP 172 /* 173 * Per-CPU run queues 174 */ 175 static struct runq runq_pcpu[MAXCPU]; 176 long runq_length[MAXCPU]; 177 178 static cpuset_t idle_cpus_mask; 179 #endif 180 181 struct pcpuidlestat { 182 u_int idlecalls; 183 u_int oldidlecalls; 184 }; 185 DPCPU_DEFINE_STATIC(struct pcpuidlestat, idlestat); 186 187 static void 188 setup_runqs(void) 189 { 190 #ifdef SMP 191 int i; 192 193 for (i = 0; i < MAXCPU; ++i) 194 runq_init(&runq_pcpu[i]); 195 #endif 196 197 runq_init(&runq); 198 } 199 200 static int 201 sysctl_kern_quantum(SYSCTL_HANDLER_ARGS) 202 { 203 int error, new_val, period; 204 205 period = 1000000 / realstathz; 206 new_val = period * sched_slice; 207 error = sysctl_handle_int(oidp, &new_val, 0, req); 208 if (error != 0 || req->newptr == NULL) 209 return (error); 210 if (new_val <= 0) 211 return (EINVAL); 212 sched_slice = imax(1, (new_val + period / 2) / period); 213 hogticks = imax(1, (2 * hz * sched_slice + realstathz / 2) / 214 realstathz); 215 return (0); 216 } 217 218 SYSCTL_NODE(_kern, OID_AUTO, sched, CTLFLAG_RD | CTLFLAG_MPSAFE, 0, 219 "Scheduler"); 220 221 SYSCTL_STRING(_kern_sched, OID_AUTO, name, CTLFLAG_RD, "4BSD", 0, 222 "Scheduler name"); 223 SYSCTL_PROC(_kern_sched, OID_AUTO, quantum, 224 CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_MPSAFE, NULL, 0, 225 sysctl_kern_quantum, "I", 226 "Quantum for timeshare threads in microseconds"); 227 SYSCTL_INT(_kern_sched, OID_AUTO, slice, CTLFLAG_RW, &sched_slice, 0, 228 "Quantum for timeshare threads in stathz ticks"); 229 #ifdef SMP 230 /* Enable forwarding of wakeups to all other cpus */ 231 static SYSCTL_NODE(_kern_sched, OID_AUTO, ipiwakeup, 232 CTLFLAG_RD | CTLFLAG_MPSAFE, NULL, 233 "Kernel SMP"); 234 235 static int runq_fuzz = 1; 236 SYSCTL_INT(_kern_sched, OID_AUTO, runq_fuzz, CTLFLAG_RW, &runq_fuzz, 0, ""); 237 238 static int forward_wakeup_enabled = 1; 239 SYSCTL_INT(_kern_sched_ipiwakeup, OID_AUTO, enabled, CTLFLAG_RW, 240 &forward_wakeup_enabled, 0, 241 "Forwarding of wakeup to idle CPUs"); 242 243 static int forward_wakeups_requested = 0; 244 SYSCTL_INT(_kern_sched_ipiwakeup, OID_AUTO, requested, CTLFLAG_RD, 245 &forward_wakeups_requested, 0, 246 "Requests for Forwarding of wakeup to idle CPUs"); 247 248 static int forward_wakeups_delivered = 0; 249 SYSCTL_INT(_kern_sched_ipiwakeup, OID_AUTO, delivered, CTLFLAG_RD, 250 &forward_wakeups_delivered, 0, 251 "Completed Forwarding of wakeup to idle CPUs"); 252 253 static int forward_wakeup_use_mask = 1; 254 SYSCTL_INT(_kern_sched_ipiwakeup, OID_AUTO, usemask, CTLFLAG_RW, 255 &forward_wakeup_use_mask, 0, 256 "Use the mask of idle cpus"); 257 258 static int forward_wakeup_use_loop = 0; 259 SYSCTL_INT(_kern_sched_ipiwakeup, OID_AUTO, useloop, CTLFLAG_RW, 260 &forward_wakeup_use_loop, 0, 261 "Use a loop to find idle cpus"); 262 263 #endif 264 #if 0 265 static int sched_followon = 0; 266 SYSCTL_INT(_kern_sched, OID_AUTO, followon, CTLFLAG_RW, 267 &sched_followon, 0, 268 "allow threads to share a quantum"); 269 #endif 270 271 SDT_PROVIDER_DEFINE(sched); 272 273 SDT_PROBE_DEFINE3(sched, , , change__pri, "struct thread *", 274 "struct proc *", "uint8_t"); 275 SDT_PROBE_DEFINE3(sched, , , dequeue, "struct thread *", 276 "struct proc *", "void *"); 277 SDT_PROBE_DEFINE4(sched, , , enqueue, "struct thread *", 278 "struct proc *", "void *", "int"); 279 SDT_PROBE_DEFINE4(sched, , , lend__pri, "struct thread *", 280 "struct proc *", "uint8_t", "struct thread *"); 281 SDT_PROBE_DEFINE2(sched, , , load__change, "int", "int"); 282 SDT_PROBE_DEFINE2(sched, , , off__cpu, "struct thread *", 283 "struct proc *"); 284 SDT_PROBE_DEFINE(sched, , , on__cpu); 285 SDT_PROBE_DEFINE(sched, , , remain__cpu); 286 SDT_PROBE_DEFINE2(sched, , , surrender, "struct thread *", 287 "struct proc *"); 288 289 static __inline void 290 sched_load_add(void) 291 { 292 293 sched_tdcnt++; 294 KTR_COUNTER0(KTR_SCHED, "load", "global load", sched_tdcnt); 295 SDT_PROBE2(sched, , , load__change, NOCPU, sched_tdcnt); 296 } 297 298 static __inline void 299 sched_load_rem(void) 300 { 301 302 sched_tdcnt--; 303 KTR_COUNTER0(KTR_SCHED, "load", "global load", sched_tdcnt); 304 SDT_PROBE2(sched, , , load__change, NOCPU, sched_tdcnt); 305 } 306 /* 307 * Arrange to reschedule if necessary, taking the priorities and 308 * schedulers into account. 309 */ 310 static void 311 maybe_resched(struct thread *td) 312 { 313 314 THREAD_LOCK_ASSERT(td, MA_OWNED); 315 if (td->td_priority < curthread->td_priority) 316 ast_sched_locked(curthread, TDA_SCHED); 317 } 318 319 /* 320 * This function is called when a thread is about to be put on run queue 321 * because it has been made runnable or its priority has been adjusted. It 322 * determines if the new thread should preempt the current thread. If so, 323 * it sets td_owepreempt to request a preemption. 324 */ 325 int 326 maybe_preempt(struct thread *td) 327 { 328 #ifdef PREEMPTION 329 struct thread *ctd; 330 int cpri, pri; 331 332 /* 333 * The new thread should not preempt the current thread if any of the 334 * following conditions are true: 335 * 336 * - The kernel is in the throes of crashing (panicstr). 337 * - The current thread has a higher (numerically lower) or 338 * equivalent priority. Note that this prevents curthread from 339 * trying to preempt to itself. 340 * - The current thread has an inhibitor set or is in the process of 341 * exiting. In this case, the current thread is about to switch 342 * out anyways, so there's no point in preempting. If we did, 343 * the current thread would not be properly resumed as well, so 344 * just avoid that whole landmine. 345 * - If the new thread's priority is not a realtime priority and 346 * the current thread's priority is not an idle priority and 347 * FULL_PREEMPTION is disabled. 348 * 349 * If all of these conditions are false, but the current thread is in 350 * a nested critical section, then we have to defer the preemption 351 * until we exit the critical section. Otherwise, switch immediately 352 * to the new thread. 353 */ 354 ctd = curthread; 355 THREAD_LOCK_ASSERT(td, MA_OWNED); 356 KASSERT((td->td_inhibitors == 0), 357 ("maybe_preempt: trying to run inhibited thread")); 358 pri = td->td_priority; 359 cpri = ctd->td_priority; 360 if (KERNEL_PANICKED() || pri >= cpri /* || dumping */ || 361 TD_IS_INHIBITED(ctd)) 362 return (0); 363 #ifndef FULL_PREEMPTION 364 if (pri > PRI_MAX_ITHD && cpri < PRI_MIN_IDLE) 365 return (0); 366 #endif 367 368 CTR0(KTR_PROC, "maybe_preempt: scheduling preemption"); 369 ctd->td_owepreempt = 1; 370 return (1); 371 #else 372 return (0); 373 #endif 374 } 375 376 /* 377 * Constants for digital decay and forget: 378 * 90% of (ts_estcpu) usage in 5 * loadav time 379 * 95% of (ts_pctcpu) usage in 60 seconds (load insensitive) 380 * Note that, as ps(1) mentions, this can let percentages 381 * total over 100% (I've seen 137.9% for 3 processes). 382 * 383 * Note that schedclock() updates ts_estcpu and p_cpticks asynchronously. 384 * 385 * We wish to decay away 90% of ts_estcpu in (5 * loadavg) seconds. 386 * That is, the system wants to compute a value of decay such 387 * that the following for loop: 388 * for (i = 0; i < (5 * loadavg); i++) 389 * ts_estcpu *= decay; 390 * will compute 391 * ts_estcpu *= 0.1; 392 * for all values of loadavg: 393 * 394 * Mathematically this loop can be expressed by saying: 395 * decay ** (5 * loadavg) ~= .1 396 * 397 * The system computes decay as: 398 * decay = (2 * loadavg) / (2 * loadavg + 1) 399 * 400 * We wish to prove that the system's computation of decay 401 * will always fulfill the equation: 402 * decay ** (5 * loadavg) ~= .1 403 * 404 * If we compute b as: 405 * b = 2 * loadavg 406 * then 407 * decay = b / (b + 1) 408 * 409 * We now need to prove two things: 410 * 1) Given factor ** (5 * loadavg) ~= .1, prove factor == b/(b+1) 411 * 2) Given b/(b+1) ** power ~= .1, prove power == (5 * loadavg) 412 * 413 * Facts: 414 * For x close to zero, exp(x) =~ 1 + x, since 415 * exp(x) = 0! + x**1/1! + x**2/2! + ... . 416 * therefore exp(-1/b) =~ 1 - (1/b) = (b-1)/b. 417 * For x close to zero, ln(1+x) =~ x, since 418 * ln(1+x) = x - x**2/2 + x**3/3 - ... -1 < x < 1 419 * therefore ln(b/(b+1)) = ln(1 - 1/(b+1)) =~ -1/(b+1). 420 * ln(.1) =~ -2.30 421 * 422 * Proof of (1): 423 * Solve (factor)**(power) =~ .1 given power (5*loadav): 424 * solving for factor, 425 * ln(factor) =~ (-2.30/5*loadav), or 426 * factor =~ exp(-1/((5/2.30)*loadav)) =~ exp(-1/(2*loadav)) = 427 * exp(-1/b) =~ (b-1)/b =~ b/(b+1). QED 428 * 429 * Proof of (2): 430 * Solve (factor)**(power) =~ .1 given factor == (b/(b+1)): 431 * solving for power, 432 * power*ln(b/(b+1)) =~ -2.30, or 433 * power =~ 2.3 * (b + 1) = 4.6*loadav + 2.3 =~ 5*loadav. QED 434 * 435 * Actual power values for the implemented algorithm are as follows: 436 * loadav: 1 2 3 4 437 * power: 5.68 10.32 14.94 19.55 438 */ 439 440 /* calculations for digital decay to forget 90% of usage in 5*loadav sec */ 441 #define loadfactor(loadav) (2 * (loadav)) 442 #define decay_cpu(loadfac, cpu) (((loadfac) * (cpu)) / ((loadfac) + FSCALE)) 443 444 /* decay 95% of `ts_pctcpu' in 60 seconds; see CCPU_SHIFT before changing */ 445 static fixpt_t ccpu = 0.95122942450071400909 * FSCALE; /* exp(-1/20) */ 446 SYSCTL_UINT(_kern, OID_AUTO, ccpu, CTLFLAG_RD, &ccpu, 0, 447 "Decay factor used for updating %CPU"); 448 449 /* 450 * If `ccpu' is not equal to `exp(-1/20)' and you still want to use the 451 * faster/more-accurate formula, you'll have to estimate CCPU_SHIFT below 452 * and possibly adjust FSHIFT in "param.h" so that (FSHIFT >= CCPU_SHIFT). 453 * 454 * To estimate CCPU_SHIFT for exp(-1/20), the following formula was used: 455 * 1 - exp(-1/20) ~= 0.0487 ~= 0.0488 == 1 (fixed pt, *11* bits). 456 * 457 * If you don't want to bother with the faster/more-accurate formula, you 458 * can set CCPU_SHIFT to (FSHIFT + 1) which will use a slower/less-accurate 459 * (more general) method of calculating the %age of CPU used by a process. 460 */ 461 #define CCPU_SHIFT 11 462 463 /* 464 * Recompute process priorities, every hz ticks. 465 * MP-safe, called without the Giant mutex. 466 */ 467 /* ARGSUSED */ 468 static void 469 schedcpu(void) 470 { 471 fixpt_t loadfac = loadfactor(averunnable.ldavg[0]); 472 struct thread *td; 473 struct proc *p; 474 struct td_sched *ts; 475 int awake; 476 477 sx_slock(&allproc_lock); 478 FOREACH_PROC_IN_SYSTEM(p) { 479 PROC_LOCK(p); 480 if (p->p_state == PRS_NEW) { 481 PROC_UNLOCK(p); 482 continue; 483 } 484 FOREACH_THREAD_IN_PROC(p, td) { 485 awake = 0; 486 ts = td_get_sched(td); 487 thread_lock(td); 488 /* 489 * Increment sleep time (if sleeping). We 490 * ignore overflow, as above. 491 */ 492 /* 493 * The td_sched slptimes are not touched in wakeup 494 * because the thread may not HAVE everything in 495 * memory? XXX I think this is out of date. 496 */ 497 if (TD_ON_RUNQ(td)) { 498 awake = 1; 499 td->td_flags &= ~TDF_DIDRUN; 500 } else if (TD_IS_RUNNING(td)) { 501 awake = 1; 502 /* Do not clear TDF_DIDRUN */ 503 } else if (td->td_flags & TDF_DIDRUN) { 504 awake = 1; 505 td->td_flags &= ~TDF_DIDRUN; 506 } 507 508 /* 509 * ts_pctcpu is only for ps and ttyinfo(). 510 */ 511 ts->ts_pctcpu = (ts->ts_pctcpu * ccpu) >> FSHIFT; 512 /* 513 * If the td_sched has been idle the entire second, 514 * stop recalculating its priority until 515 * it wakes up. 516 */ 517 if (ts->ts_cpticks != 0) { 518 #if (FSHIFT >= CCPU_SHIFT) 519 ts->ts_pctcpu += (realstathz == 100) 520 ? ((fixpt_t) ts->ts_cpticks) << 521 (FSHIFT - CCPU_SHIFT) : 522 100 * (((fixpt_t) ts->ts_cpticks) 523 << (FSHIFT - CCPU_SHIFT)) / realstathz; 524 #else 525 ts->ts_pctcpu += ((FSCALE - ccpu) * 526 (ts->ts_cpticks * 527 FSCALE / realstathz)) >> FSHIFT; 528 #endif 529 ts->ts_cpticks = 0; 530 } 531 /* 532 * If there are ANY running threads in this process, 533 * then don't count it as sleeping. 534 * XXX: this is broken. 535 */ 536 if (awake) { 537 if (ts->ts_slptime > 1) { 538 /* 539 * In an ideal world, this should not 540 * happen, because whoever woke us 541 * up from the long sleep should have 542 * unwound the slptime and reset our 543 * priority before we run at the stale 544 * priority. Should KASSERT at some 545 * point when all the cases are fixed. 546 */ 547 updatepri(td); 548 } 549 ts->ts_slptime = 0; 550 } else 551 ts->ts_slptime++; 552 if (ts->ts_slptime > 1) { 553 thread_unlock(td); 554 continue; 555 } 556 ts->ts_estcpu = decay_cpu(loadfac, ts->ts_estcpu); 557 resetpriority(td); 558 resetpriority_thread(td); 559 thread_unlock(td); 560 } 561 PROC_UNLOCK(p); 562 } 563 sx_sunlock(&allproc_lock); 564 } 565 566 /* 567 * Main loop for a kthread that executes schedcpu once a second. 568 */ 569 static void 570 schedcpu_thread(void) 571 { 572 573 for (;;) { 574 schedcpu(); 575 pause("-", hz); 576 } 577 } 578 579 /* 580 * Recalculate the priority of a process after it has slept for a while. 581 * For all load averages >= 1 and max ts_estcpu of 255, sleeping for at 582 * least six times the loadfactor will decay ts_estcpu to zero. 583 */ 584 static void 585 updatepri(struct thread *td) 586 { 587 struct td_sched *ts; 588 fixpt_t loadfac; 589 unsigned int newcpu; 590 591 ts = td_get_sched(td); 592 loadfac = loadfactor(averunnable.ldavg[0]); 593 if (ts->ts_slptime > 5 * loadfac) 594 ts->ts_estcpu = 0; 595 else { 596 newcpu = ts->ts_estcpu; 597 ts->ts_slptime--; /* was incremented in schedcpu() */ 598 while (newcpu && --ts->ts_slptime) 599 newcpu = decay_cpu(loadfac, newcpu); 600 ts->ts_estcpu = newcpu; 601 } 602 } 603 604 /* 605 * Compute the priority of a process when running in user mode. 606 * Arrange to reschedule if the resulting priority is better 607 * than that of the current process. 608 */ 609 static void 610 resetpriority(struct thread *td) 611 { 612 u_int newpriority; 613 614 if (td->td_pri_class != PRI_TIMESHARE) 615 return; 616 newpriority = PUSER + 617 td_get_sched(td)->ts_estcpu / INVERSE_ESTCPU_WEIGHT + 618 NICE_WEIGHT * (td->td_proc->p_nice - PRIO_MIN); 619 newpriority = min(max(newpriority, PRI_MIN_TIMESHARE), 620 PRI_MAX_TIMESHARE); 621 sched_user_prio(td, newpriority); 622 } 623 624 /* 625 * Update the thread's priority when the associated process's user 626 * priority changes. 627 */ 628 static void 629 resetpriority_thread(struct thread *td) 630 { 631 632 /* Only change threads with a time sharing user priority. */ 633 if (td->td_priority < PRI_MIN_TIMESHARE || 634 td->td_priority > PRI_MAX_TIMESHARE) 635 return; 636 637 /* XXX the whole needresched thing is broken, but not silly. */ 638 maybe_resched(td); 639 640 sched_prio(td, td->td_user_pri); 641 } 642 643 /* ARGSUSED */ 644 static void 645 sched_setup(void *dummy) 646 { 647 648 setup_runqs(); 649 650 /* Account for thread0. */ 651 sched_load_add(); 652 } 653 654 /* 655 * This routine determines time constants after stathz and hz are setup. 656 */ 657 static void 658 sched_initticks(void *dummy) 659 { 660 661 realstathz = stathz ? stathz : hz; 662 sched_slice = realstathz / 10; /* ~100ms */ 663 hogticks = imax(1, (2 * hz * sched_slice + realstathz / 2) / 664 realstathz); 665 } 666 667 /* External interfaces start here */ 668 669 /* 670 * Very early in the boot some setup of scheduler-specific 671 * parts of proc0 and of some scheduler resources needs to be done. 672 * Called from: 673 * proc0_init() 674 */ 675 void 676 schedinit(void) 677 { 678 679 /* 680 * Set up the scheduler specific parts of thread0. 681 */ 682 thread0.td_lock = &sched_lock; 683 td_get_sched(&thread0)->ts_slice = sched_slice; 684 mtx_init(&sched_lock, "sched lock", NULL, MTX_SPIN); 685 } 686 687 void 688 schedinit_ap(void) 689 { 690 691 /* Nothing needed. */ 692 } 693 694 bool 695 sched_runnable(void) 696 { 697 #ifdef SMP 698 return (runq_not_empty(&runq) || 699 runq_not_empty(&runq_pcpu[PCPU_GET(cpuid)])); 700 #else 701 return (runq_not_empty(&runq)); 702 #endif 703 } 704 705 int 706 sched_rr_interval(void) 707 { 708 709 /* Convert sched_slice from stathz to hz. */ 710 return (imax(1, (sched_slice * hz + realstathz / 2) / realstathz)); 711 } 712 713 SCHED_STAT_DEFINE(ithread_demotions, "Interrupt thread priority demotions"); 714 SCHED_STAT_DEFINE(ithread_preemptions, 715 "Interrupt thread preemptions due to time-sharing"); 716 717 /* 718 * We adjust the priority of the current process. The priority of a 719 * process gets worse as it accumulates CPU time. The cpu usage 720 * estimator (ts_estcpu) is increased here. resetpriority() will 721 * compute a different priority each time ts_estcpu increases by 722 * INVERSE_ESTCPU_WEIGHT (until PRI_MAX_TIMESHARE is reached). The 723 * cpu usage estimator ramps up quite quickly when the process is 724 * running (linearly), and decays away exponentially, at a rate which 725 * is proportionally slower when the system is busy. The basic 726 * principle is that the system will 90% forget that the process used 727 * a lot of CPU time in 5 * loadav seconds. This causes the system to 728 * favor processes which haven't run much recently, and to round-robin 729 * among other processes. 730 */ 731 static void 732 sched_clock_tick(struct thread *td) 733 { 734 struct pcpuidlestat *stat; 735 struct td_sched *ts; 736 737 THREAD_LOCK_ASSERT(td, MA_OWNED); 738 ts = td_get_sched(td); 739 740 ts->ts_cpticks++; 741 ts->ts_estcpu = ESTCPULIM(ts->ts_estcpu + 1); 742 if ((ts->ts_estcpu % INVERSE_ESTCPU_WEIGHT) == 0) { 743 resetpriority(td); 744 resetpriority_thread(td); 745 } 746 747 /* 748 * Force a context switch if the current thread has used up a full 749 * time slice (default is 100ms). 750 */ 751 if (!TD_IS_IDLETHREAD(td) && --ts->ts_slice <= 0) { 752 ts->ts_slice = sched_slice; 753 754 /* 755 * If an ithread uses a full quantum, demote its 756 * priority and preempt it. 757 */ 758 if (PRI_BASE(td->td_pri_class) == PRI_ITHD) { 759 SCHED_STAT_INC(ithread_preemptions); 760 td->td_owepreempt = 1; 761 if (td->td_base_pri + RQ_PPQ < PRI_MAX_ITHD) { 762 SCHED_STAT_INC(ithread_demotions); 763 sched_prio(td, td->td_base_pri + RQ_PPQ); 764 } 765 } else { 766 td->td_flags |= TDF_SLICEEND; 767 ast_sched_locked(td, TDA_SCHED); 768 } 769 } 770 771 stat = DPCPU_PTR(idlestat); 772 stat->oldidlecalls = stat->idlecalls; 773 stat->idlecalls = 0; 774 } 775 776 void 777 sched_clock(struct thread *td, int cnt) 778 { 779 780 for ( ; cnt > 0; cnt--) 781 sched_clock_tick(td); 782 } 783 784 /* 785 * Charge child's scheduling CPU usage to parent. 786 */ 787 void 788 sched_exit(struct proc *p, struct thread *td) 789 { 790 791 KTR_STATE1(KTR_SCHED, "thread", sched_tdname(td), "proc exit", 792 "prio:%d", td->td_priority); 793 794 PROC_LOCK_ASSERT(p, MA_OWNED); 795 sched_exit_thread(FIRST_THREAD_IN_PROC(p), td); 796 } 797 798 void 799 sched_exit_thread(struct thread *td, struct thread *child) 800 { 801 802 KTR_STATE1(KTR_SCHED, "thread", sched_tdname(child), "exit", 803 "prio:%d", child->td_priority); 804 thread_lock(td); 805 td_get_sched(td)->ts_estcpu = ESTCPULIM(td_get_sched(td)->ts_estcpu + 806 td_get_sched(child)->ts_estcpu); 807 thread_unlock(td); 808 thread_lock(child); 809 if ((child->td_flags & TDF_NOLOAD) == 0) 810 sched_load_rem(); 811 thread_unlock(child); 812 } 813 814 void 815 sched_fork(struct thread *td, struct thread *childtd) 816 { 817 sched_fork_thread(td, childtd); 818 } 819 820 void 821 sched_fork_thread(struct thread *td, struct thread *childtd) 822 { 823 struct td_sched *ts, *tsc; 824 825 childtd->td_oncpu = NOCPU; 826 childtd->td_lastcpu = NOCPU; 827 childtd->td_lock = &sched_lock; 828 childtd->td_cpuset = cpuset_ref(td->td_cpuset); 829 childtd->td_domain.dr_policy = td->td_cpuset->cs_domain; 830 childtd->td_priority = childtd->td_base_pri; 831 ts = td_get_sched(childtd); 832 bzero(ts, sizeof(*ts)); 833 tsc = td_get_sched(td); 834 ts->ts_estcpu = tsc->ts_estcpu; 835 ts->ts_flags |= (tsc->ts_flags & TSF_AFFINITY); 836 ts->ts_slice = 1; 837 } 838 839 void 840 sched_nice(struct proc *p, int nice) 841 { 842 struct thread *td; 843 844 PROC_LOCK_ASSERT(p, MA_OWNED); 845 p->p_nice = nice; 846 FOREACH_THREAD_IN_PROC(p, td) { 847 thread_lock(td); 848 resetpriority(td); 849 resetpriority_thread(td); 850 thread_unlock(td); 851 } 852 } 853 854 void 855 sched_class(struct thread *td, int class) 856 { 857 THREAD_LOCK_ASSERT(td, MA_OWNED); 858 td->td_pri_class = class; 859 } 860 861 /* 862 * Adjust the priority of a thread. 863 */ 864 static void 865 sched_priority(struct thread *td, u_char prio) 866 { 867 868 KTR_POINT3(KTR_SCHED, "thread", sched_tdname(td), "priority change", 869 "prio:%d", td->td_priority, "new prio:%d", prio, KTR_ATTR_LINKED, 870 sched_tdname(curthread)); 871 SDT_PROBE3(sched, , , change__pri, td, td->td_proc, prio); 872 if (td != curthread && prio > td->td_priority) { 873 KTR_POINT3(KTR_SCHED, "thread", sched_tdname(curthread), 874 "lend prio", "prio:%d", td->td_priority, "new prio:%d", 875 prio, KTR_ATTR_LINKED, sched_tdname(td)); 876 SDT_PROBE4(sched, , , lend__pri, td, td->td_proc, prio, 877 curthread); 878 } 879 THREAD_LOCK_ASSERT(td, MA_OWNED); 880 if (td->td_priority == prio) 881 return; 882 td->td_priority = prio; 883 if (TD_ON_RUNQ(td) && td->td_rqindex != RQ_PRI_TO_QUEUE_IDX(prio)) { 884 sched_rem(td); 885 sched_add(td, SRQ_BORING | SRQ_HOLDTD); 886 } 887 } 888 889 /* 890 * Update a thread's priority when it is lent another thread's 891 * priority. 892 */ 893 void 894 sched_lend_prio(struct thread *td, u_char prio) 895 { 896 897 td->td_flags |= TDF_BORROWING; 898 sched_priority(td, prio); 899 } 900 901 /* 902 * Restore a thread's priority when priority propagation is 903 * over. The prio argument is the minimum priority the thread 904 * needs to have to satisfy other possible priority lending 905 * requests. If the thread's regulary priority is less 906 * important than prio the thread will keep a priority boost 907 * of prio. 908 */ 909 void 910 sched_unlend_prio(struct thread *td, u_char prio) 911 { 912 u_char base_pri; 913 914 if (td->td_base_pri >= PRI_MIN_TIMESHARE && 915 td->td_base_pri <= PRI_MAX_TIMESHARE) 916 base_pri = td->td_user_pri; 917 else 918 base_pri = td->td_base_pri; 919 if (prio >= base_pri) { 920 td->td_flags &= ~TDF_BORROWING; 921 sched_prio(td, base_pri); 922 } else 923 sched_lend_prio(td, prio); 924 } 925 926 void 927 sched_prio(struct thread *td, u_char prio) 928 { 929 u_char oldprio; 930 931 /* First, update the base priority. */ 932 td->td_base_pri = prio; 933 934 /* 935 * If the thread is borrowing another thread's priority, don't ever 936 * lower the priority. 937 */ 938 if (td->td_flags & TDF_BORROWING && td->td_priority < prio) 939 return; 940 941 /* Change the real priority. */ 942 oldprio = td->td_priority; 943 sched_priority(td, prio); 944 945 /* 946 * If the thread is on a turnstile, then let the turnstile update 947 * its state. 948 */ 949 if (TD_ON_LOCK(td) && oldprio != prio) 950 turnstile_adjust(td, oldprio); 951 } 952 953 void 954 sched_ithread_prio(struct thread *td, u_char prio) 955 { 956 THREAD_LOCK_ASSERT(td, MA_OWNED); 957 MPASS(td->td_pri_class == PRI_ITHD); 958 td->td_base_ithread_pri = prio; 959 sched_prio(td, prio); 960 } 961 962 void 963 sched_user_prio(struct thread *td, u_char prio) 964 { 965 966 THREAD_LOCK_ASSERT(td, MA_OWNED); 967 td->td_base_user_pri = prio; 968 if (td->td_lend_user_pri <= prio) 969 return; 970 td->td_user_pri = prio; 971 } 972 973 void 974 sched_lend_user_prio(struct thread *td, u_char prio) 975 { 976 977 THREAD_LOCK_ASSERT(td, MA_OWNED); 978 td->td_lend_user_pri = prio; 979 td->td_user_pri = min(prio, td->td_base_user_pri); 980 if (td->td_priority > td->td_user_pri) 981 sched_prio(td, td->td_user_pri); 982 else if (td->td_priority != td->td_user_pri) 983 ast_sched_locked(td, TDA_SCHED); 984 } 985 986 /* 987 * Like the above but first check if there is anything to do. 988 */ 989 void 990 sched_lend_user_prio_cond(struct thread *td, u_char prio) 991 { 992 993 if (td->td_lend_user_pri == prio) 994 return; 995 996 thread_lock(td); 997 sched_lend_user_prio(td, prio); 998 thread_unlock(td); 999 } 1000 1001 void 1002 sched_sleep(struct thread *td, int pri) 1003 { 1004 1005 THREAD_LOCK_ASSERT(td, MA_OWNED); 1006 td->td_slptick = ticks; 1007 td_get_sched(td)->ts_slptime = 0; 1008 if (pri != 0 && PRI_BASE(td->td_pri_class) == PRI_TIMESHARE) 1009 sched_prio(td, pri); 1010 } 1011 1012 void 1013 sched_switch(struct thread *td, int flags) 1014 { 1015 struct thread *newtd; 1016 struct mtx *tmtx; 1017 int preempted; 1018 1019 tmtx = &sched_lock; 1020 1021 THREAD_LOCK_ASSERT(td, MA_OWNED); 1022 1023 td->td_lastcpu = td->td_oncpu; 1024 preempted = (td->td_flags & TDF_SLICEEND) == 0 && 1025 (flags & SW_PREEMPT) != 0; 1026 td->td_flags &= ~TDF_SLICEEND; 1027 ast_unsched_locked(td, TDA_SCHED); 1028 td->td_owepreempt = 0; 1029 td->td_oncpu = NOCPU; 1030 1031 /* 1032 * At the last moment, if this thread is still marked RUNNING, 1033 * then put it back on the run queue as it has not been suspended 1034 * or stopped or any thing else similar. We never put the idle 1035 * threads on the run queue, however. 1036 */ 1037 if (td->td_flags & TDF_IDLETD) { 1038 TD_SET_CAN_RUN(td); 1039 #ifdef SMP 1040 CPU_CLR(PCPU_GET(cpuid), &idle_cpus_mask); 1041 #endif 1042 } else { 1043 if (TD_IS_RUNNING(td)) { 1044 /* Put us back on the run queue. */ 1045 sched_add(td, SRQ_HOLDTD | SRQ_OURSELF | SRQ_YIELDING | 1046 (preempted ? SRQ_PREEMPTED : 0)); 1047 } 1048 } 1049 1050 /* 1051 * Switch to the sched lock to fix things up and pick 1052 * a new thread. Block the td_lock in order to avoid 1053 * breaking the critical path. 1054 */ 1055 if (td->td_lock != &sched_lock) { 1056 mtx_lock_spin(&sched_lock); 1057 tmtx = thread_lock_block(td); 1058 mtx_unlock_spin(tmtx); 1059 } 1060 1061 if ((td->td_flags & TDF_NOLOAD) == 0) 1062 sched_load_rem(); 1063 1064 newtd = choosethread(); 1065 MPASS(newtd->td_lock == &sched_lock); 1066 1067 #if (KTR_COMPILE & KTR_SCHED) != 0 1068 if (TD_IS_IDLETHREAD(td)) 1069 KTR_STATE1(KTR_SCHED, "thread", sched_tdname(td), "idle", 1070 "prio:%d", td->td_priority); 1071 else 1072 KTR_STATE3(KTR_SCHED, "thread", sched_tdname(td), KTDSTATE(td), 1073 "prio:%d", td->td_priority, "wmesg:\"%s\"", td->td_wmesg, 1074 "lockname:\"%s\"", td->td_lockname); 1075 #endif 1076 1077 if (td != newtd) { 1078 #ifdef HWPMC_HOOKS 1079 if (PMC_PROC_IS_USING_PMCS(td->td_proc)) 1080 PMC_SWITCH_CONTEXT(td, PMC_FN_CSW_OUT); 1081 #endif 1082 1083 #ifdef HWT_HOOKS 1084 HWT_CALL_HOOK(td, HWT_SWITCH_OUT, NULL); 1085 HWT_CALL_HOOK(newtd, HWT_SWITCH_IN, NULL); 1086 #endif 1087 1088 SDT_PROBE2(sched, , , off__cpu, newtd, newtd->td_proc); 1089 1090 /* I feel sleepy */ 1091 lock_profile_release_lock(&sched_lock.lock_object, true); 1092 #ifdef KDTRACE_HOOKS 1093 /* 1094 * If DTrace has set the active vtime enum to anything 1095 * other than INACTIVE (0), then it should have set the 1096 * function to call. 1097 */ 1098 if (dtrace_vtime_active) 1099 (*dtrace_vtime_switch_func)(newtd); 1100 #endif 1101 1102 cpu_switch(td, newtd, tmtx); 1103 lock_profile_obtain_lock_success(&sched_lock.lock_object, true, 1104 0, 0, __FILE__, __LINE__); 1105 /* 1106 * Where am I? What year is it? 1107 * We are in the same thread that went to sleep above, 1108 * but any amount of time may have passed. All our context 1109 * will still be available as will local variables. 1110 * PCPU values however may have changed as we may have 1111 * changed CPU so don't trust cached values of them. 1112 * New threads will go to fork_exit() instead of here 1113 * so if you change things here you may need to change 1114 * things there too. 1115 * 1116 * If the thread above was exiting it will never wake 1117 * up again here, so either it has saved everything it 1118 * needed to, or the thread_wait() or wait() will 1119 * need to reap it. 1120 */ 1121 1122 SDT_PROBE0(sched, , , on__cpu); 1123 #ifdef HWPMC_HOOKS 1124 if (PMC_PROC_IS_USING_PMCS(td->td_proc)) 1125 PMC_SWITCH_CONTEXT(td, PMC_FN_CSW_IN); 1126 #endif 1127 } else { 1128 td->td_lock = &sched_lock; 1129 SDT_PROBE0(sched, , , remain__cpu); 1130 } 1131 1132 KTR_STATE1(KTR_SCHED, "thread", sched_tdname(td), "running", 1133 "prio:%d", td->td_priority); 1134 1135 #ifdef SMP 1136 if (td->td_flags & TDF_IDLETD) 1137 CPU_SET(PCPU_GET(cpuid), &idle_cpus_mask); 1138 #endif 1139 sched_lock.mtx_lock = (uintptr_t)td; 1140 td->td_oncpu = PCPU_GET(cpuid); 1141 spinlock_enter(); 1142 mtx_unlock_spin(&sched_lock); 1143 } 1144 1145 void 1146 sched_wakeup(struct thread *td, int srqflags) 1147 { 1148 struct td_sched *ts; 1149 1150 THREAD_LOCK_ASSERT(td, MA_OWNED); 1151 ts = td_get_sched(td); 1152 if (ts->ts_slptime > 1) { 1153 updatepri(td); 1154 resetpriority(td); 1155 } 1156 td->td_slptick = 0; 1157 ts->ts_slptime = 0; 1158 ts->ts_slice = sched_slice; 1159 1160 /* 1161 * When resuming an idle ithread, restore its base ithread 1162 * priority. 1163 */ 1164 if (PRI_BASE(td->td_pri_class) == PRI_ITHD && 1165 td->td_base_pri != td->td_base_ithread_pri) 1166 sched_prio(td, td->td_base_ithread_pri); 1167 1168 sched_add(td, srqflags); 1169 } 1170 1171 #ifdef SMP 1172 static int 1173 forward_wakeup(int cpunum) 1174 { 1175 struct pcpu *pc; 1176 cpuset_t dontuse, map, map2; 1177 u_int id, me; 1178 int iscpuset; 1179 1180 mtx_assert(&sched_lock, MA_OWNED); 1181 1182 CTR0(KTR_RUNQ, "forward_wakeup()"); 1183 1184 if ((!forward_wakeup_enabled) || 1185 (forward_wakeup_use_mask == 0 && forward_wakeup_use_loop == 0)) 1186 return (0); 1187 if (!smp_started || KERNEL_PANICKED()) 1188 return (0); 1189 1190 forward_wakeups_requested++; 1191 1192 /* 1193 * Check the idle mask we received against what we calculated 1194 * before in the old version. 1195 */ 1196 me = PCPU_GET(cpuid); 1197 1198 /* Don't bother if we should be doing it ourself. */ 1199 if (CPU_ISSET(me, &idle_cpus_mask) && 1200 (cpunum == NOCPU || me == cpunum)) 1201 return (0); 1202 1203 CPU_SETOF(me, &dontuse); 1204 CPU_OR(&dontuse, &dontuse, &stopped_cpus); 1205 CPU_OR(&dontuse, &dontuse, &hlt_cpus_mask); 1206 CPU_ZERO(&map2); 1207 if (forward_wakeup_use_loop) { 1208 STAILQ_FOREACH(pc, &cpuhead, pc_allcpu) { 1209 id = pc->pc_cpuid; 1210 if (!CPU_ISSET(id, &dontuse) && 1211 pc->pc_curthread == pc->pc_idlethread) { 1212 CPU_SET(id, &map2); 1213 } 1214 } 1215 } 1216 1217 if (forward_wakeup_use_mask) { 1218 map = idle_cpus_mask; 1219 CPU_ANDNOT(&map, &map, &dontuse); 1220 1221 /* If they are both on, compare and use loop if different. */ 1222 if (forward_wakeup_use_loop) { 1223 if (CPU_CMP(&map, &map2)) { 1224 printf("map != map2, loop method preferred\n"); 1225 map = map2; 1226 } 1227 } 1228 } else { 1229 map = map2; 1230 } 1231 1232 /* If we only allow a specific CPU, then mask off all the others. */ 1233 if (cpunum != NOCPU) { 1234 KASSERT((cpunum <= mp_maxcpus),("forward_wakeup: bad cpunum.")); 1235 iscpuset = CPU_ISSET(cpunum, &map); 1236 if (iscpuset == 0) 1237 CPU_ZERO(&map); 1238 else 1239 CPU_SETOF(cpunum, &map); 1240 } 1241 if (!CPU_EMPTY(&map)) { 1242 forward_wakeups_delivered++; 1243 STAILQ_FOREACH(pc, &cpuhead, pc_allcpu) { 1244 id = pc->pc_cpuid; 1245 if (!CPU_ISSET(id, &map)) 1246 continue; 1247 if (cpu_idle_wakeup(pc->pc_cpuid)) 1248 CPU_CLR(id, &map); 1249 } 1250 if (!CPU_EMPTY(&map)) 1251 ipi_selected(map, IPI_AST); 1252 return (1); 1253 } 1254 if (cpunum == NOCPU) 1255 printf("forward_wakeup: Idle processor not found\n"); 1256 return (0); 1257 } 1258 1259 static void 1260 kick_other_cpu(int pri, int cpuid) 1261 { 1262 struct pcpu *pcpu; 1263 int cpri; 1264 1265 pcpu = pcpu_find(cpuid); 1266 if (CPU_ISSET(cpuid, &idle_cpus_mask)) { 1267 forward_wakeups_delivered++; 1268 if (!cpu_idle_wakeup(cpuid)) 1269 ipi_cpu(cpuid, IPI_AST); 1270 return; 1271 } 1272 1273 cpri = pcpu->pc_curthread->td_priority; 1274 if (pri >= cpri) 1275 return; 1276 1277 #if defined(IPI_PREEMPTION) && defined(PREEMPTION) 1278 #if !defined(FULL_PREEMPTION) 1279 if (pri <= PRI_MAX_ITHD) 1280 #endif /* ! FULL_PREEMPTION */ 1281 { 1282 ipi_cpu(cpuid, IPI_PREEMPT); 1283 return; 1284 } 1285 #endif /* defined(IPI_PREEMPTION) && defined(PREEMPTION) */ 1286 1287 if (pcpu->pc_curthread->td_lock == &sched_lock) { 1288 ast_sched_locked(pcpu->pc_curthread, TDA_SCHED); 1289 ipi_cpu(cpuid, IPI_AST); 1290 } 1291 } 1292 #endif /* SMP */ 1293 1294 #ifdef SMP 1295 static int 1296 sched_pickcpu(struct thread *td) 1297 { 1298 int best, cpu; 1299 1300 mtx_assert(&sched_lock, MA_OWNED); 1301 1302 if (td->td_lastcpu != NOCPU && THREAD_CAN_SCHED(td, td->td_lastcpu)) 1303 best = td->td_lastcpu; 1304 else 1305 best = NOCPU; 1306 CPU_FOREACH(cpu) { 1307 if (!THREAD_CAN_SCHED(td, cpu)) 1308 continue; 1309 1310 if (best == NOCPU) 1311 best = cpu; 1312 else if (runq_length[cpu] < runq_length[best]) 1313 best = cpu; 1314 } 1315 KASSERT(best != NOCPU, ("no valid CPUs")); 1316 1317 return (best); 1318 } 1319 #endif 1320 1321 void 1322 sched_add(struct thread *td, int flags) 1323 #ifdef SMP 1324 { 1325 cpuset_t tidlemsk; 1326 struct td_sched *ts; 1327 u_int cpu, cpuid; 1328 int forwarded = 0; 1329 int single_cpu = 0; 1330 1331 ts = td_get_sched(td); 1332 THREAD_LOCK_ASSERT(td, MA_OWNED); 1333 KASSERT((td->td_inhibitors == 0), 1334 ("sched_add: trying to run inhibited thread")); 1335 KASSERT((TD_CAN_RUN(td) || TD_IS_RUNNING(td)), 1336 ("sched_add: bad thread state")); 1337 KASSERT(td->td_flags & TDF_INMEM, 1338 ("sched_add: thread swapped out")); 1339 1340 KTR_STATE2(KTR_SCHED, "thread", sched_tdname(td), "runq add", 1341 "prio:%d", td->td_priority, KTR_ATTR_LINKED, 1342 sched_tdname(curthread)); 1343 KTR_POINT1(KTR_SCHED, "thread", sched_tdname(curthread), "wokeup", 1344 KTR_ATTR_LINKED, sched_tdname(td)); 1345 SDT_PROBE4(sched, , , enqueue, td, td->td_proc, NULL, 1346 flags & SRQ_PREEMPTED); 1347 1348 /* 1349 * Now that the thread is moving to the run-queue, set the lock 1350 * to the scheduler's lock. 1351 */ 1352 if (td->td_lock != &sched_lock) { 1353 mtx_lock_spin(&sched_lock); 1354 if ((flags & SRQ_HOLD) != 0) 1355 td->td_lock = &sched_lock; 1356 else 1357 thread_lock_set(td, &sched_lock); 1358 } 1359 TD_SET_RUNQ(td); 1360 1361 /* 1362 * If SMP is started and the thread is pinned or otherwise limited to 1363 * a specific set of CPUs, queue the thread to a per-CPU run queue. 1364 * Otherwise, queue the thread to the global run queue. 1365 * 1366 * If SMP has not yet been started we must use the global run queue 1367 * as per-CPU state may not be initialized yet and we may crash if we 1368 * try to access the per-CPU run queues. 1369 */ 1370 if (smp_started && (td->td_pinned != 0 || td->td_flags & TDF_BOUND || 1371 ts->ts_flags & TSF_AFFINITY)) { 1372 if (td->td_pinned != 0) 1373 cpu = td->td_lastcpu; 1374 else if (td->td_flags & TDF_BOUND) { 1375 /* Find CPU from bound runq. */ 1376 KASSERT(SKE_RUNQ_PCPU(ts), 1377 ("sched_add: bound td_sched not on cpu runq")); 1378 cpu = ts->ts_runq - &runq_pcpu[0]; 1379 } else 1380 /* Find a valid CPU for our cpuset */ 1381 cpu = sched_pickcpu(td); 1382 ts->ts_runq = &runq_pcpu[cpu]; 1383 single_cpu = 1; 1384 CTR3(KTR_RUNQ, 1385 "sched_add: Put td_sched:%p(td:%p) on cpu%d runq", ts, td, 1386 cpu); 1387 } else { 1388 CTR2(KTR_RUNQ, 1389 "sched_add: adding td_sched:%p (td:%p) to gbl runq", ts, 1390 td); 1391 cpu = NOCPU; 1392 ts->ts_runq = &runq; 1393 } 1394 1395 if ((td->td_flags & TDF_NOLOAD) == 0) 1396 sched_load_add(); 1397 runq_add(ts->ts_runq, td, flags); 1398 if (cpu != NOCPU) 1399 runq_length[cpu]++; 1400 1401 cpuid = PCPU_GET(cpuid); 1402 if (single_cpu && cpu != cpuid) { 1403 kick_other_cpu(td->td_priority, cpu); 1404 } else { 1405 if (!single_cpu) { 1406 tidlemsk = idle_cpus_mask; 1407 CPU_ANDNOT(&tidlemsk, &tidlemsk, &hlt_cpus_mask); 1408 CPU_CLR(cpuid, &tidlemsk); 1409 1410 if (!CPU_ISSET(cpuid, &idle_cpus_mask) && 1411 ((flags & SRQ_INTR) == 0) && 1412 !CPU_EMPTY(&tidlemsk)) 1413 forwarded = forward_wakeup(cpu); 1414 } 1415 1416 if (!forwarded) { 1417 if (!maybe_preempt(td)) 1418 maybe_resched(td); 1419 } 1420 } 1421 if ((flags & SRQ_HOLDTD) == 0) 1422 thread_unlock(td); 1423 } 1424 #else /* SMP */ 1425 { 1426 struct td_sched *ts; 1427 1428 ts = td_get_sched(td); 1429 THREAD_LOCK_ASSERT(td, MA_OWNED); 1430 KASSERT((td->td_inhibitors == 0), 1431 ("sched_add: trying to run inhibited thread")); 1432 KASSERT((TD_CAN_RUN(td) || TD_IS_RUNNING(td)), 1433 ("sched_add: bad thread state")); 1434 KASSERT(td->td_flags & TDF_INMEM, 1435 ("sched_add: thread swapped out")); 1436 KTR_STATE2(KTR_SCHED, "thread", sched_tdname(td), "runq add", 1437 "prio:%d", td->td_priority, KTR_ATTR_LINKED, 1438 sched_tdname(curthread)); 1439 KTR_POINT1(KTR_SCHED, "thread", sched_tdname(curthread), "wokeup", 1440 KTR_ATTR_LINKED, sched_tdname(td)); 1441 SDT_PROBE4(sched, , , enqueue, td, td->td_proc, NULL, 1442 flags & SRQ_PREEMPTED); 1443 1444 /* 1445 * Now that the thread is moving to the run-queue, set the lock 1446 * to the scheduler's lock. 1447 */ 1448 if (td->td_lock != &sched_lock) { 1449 mtx_lock_spin(&sched_lock); 1450 if ((flags & SRQ_HOLD) != 0) 1451 td->td_lock = &sched_lock; 1452 else 1453 thread_lock_set(td, &sched_lock); 1454 } 1455 TD_SET_RUNQ(td); 1456 CTR2(KTR_RUNQ, "sched_add: adding td_sched:%p (td:%p) to runq", ts, td); 1457 ts->ts_runq = &runq; 1458 1459 if ((td->td_flags & TDF_NOLOAD) == 0) 1460 sched_load_add(); 1461 runq_add(ts->ts_runq, td, flags); 1462 if (!maybe_preempt(td)) 1463 maybe_resched(td); 1464 if ((flags & SRQ_HOLDTD) == 0) 1465 thread_unlock(td); 1466 } 1467 #endif /* SMP */ 1468 1469 void 1470 sched_rem(struct thread *td) 1471 { 1472 struct td_sched *ts; 1473 1474 ts = td_get_sched(td); 1475 KASSERT(td->td_flags & TDF_INMEM, 1476 ("sched_rem: thread swapped out")); 1477 KASSERT(TD_ON_RUNQ(td), 1478 ("sched_rem: thread not on run queue")); 1479 mtx_assert(&sched_lock, MA_OWNED); 1480 KTR_STATE2(KTR_SCHED, "thread", sched_tdname(td), "runq rem", 1481 "prio:%d", td->td_priority, KTR_ATTR_LINKED, 1482 sched_tdname(curthread)); 1483 SDT_PROBE3(sched, , , dequeue, td, td->td_proc, NULL); 1484 1485 if ((td->td_flags & TDF_NOLOAD) == 0) 1486 sched_load_rem(); 1487 #ifdef SMP 1488 if (ts->ts_runq != &runq) 1489 runq_length[ts->ts_runq - runq_pcpu]--; 1490 #endif 1491 runq_remove(ts->ts_runq, td); 1492 TD_SET_CAN_RUN(td); 1493 } 1494 1495 /* 1496 * Select threads to run. Note that running threads still consume a 1497 * slot. 1498 */ 1499 struct thread * 1500 sched_choose(void) 1501 { 1502 struct thread *td; 1503 struct runq *rq; 1504 1505 mtx_assert(&sched_lock, MA_OWNED); 1506 #ifdef SMP 1507 struct thread *tdcpu; 1508 1509 rq = &runq; 1510 td = runq_choose_fuzz(&runq, runq_fuzz); 1511 tdcpu = runq_choose(&runq_pcpu[PCPU_GET(cpuid)]); 1512 1513 if (td == NULL || 1514 (tdcpu != NULL && 1515 tdcpu->td_priority < td->td_priority)) { 1516 CTR2(KTR_RUNQ, "choosing td %p from pcpu runq %d", tdcpu, 1517 PCPU_GET(cpuid)); 1518 td = tdcpu; 1519 rq = &runq_pcpu[PCPU_GET(cpuid)]; 1520 } else { 1521 CTR1(KTR_RUNQ, "choosing td_sched %p from main runq", td); 1522 } 1523 1524 #else 1525 rq = &runq; 1526 td = runq_choose(&runq); 1527 #endif 1528 1529 if (td) { 1530 #ifdef SMP 1531 if (td == tdcpu) 1532 runq_length[PCPU_GET(cpuid)]--; 1533 #endif 1534 runq_remove(rq, td); 1535 td->td_flags |= TDF_DIDRUN; 1536 1537 KASSERT(td->td_flags & TDF_INMEM, 1538 ("sched_choose: thread swapped out")); 1539 return (td); 1540 } 1541 return (PCPU_GET(idlethread)); 1542 } 1543 1544 void 1545 sched_preempt(struct thread *td) 1546 { 1547 int flags; 1548 1549 SDT_PROBE2(sched, , , surrender, td, td->td_proc); 1550 if (td->td_critnest > 1) { 1551 td->td_owepreempt = 1; 1552 } else { 1553 thread_lock(td); 1554 flags = SW_INVOL | SW_PREEMPT; 1555 flags |= TD_IS_IDLETHREAD(td) ? SWT_REMOTEWAKEIDLE : 1556 SWT_REMOTEPREEMPT; 1557 mi_switch(flags); 1558 } 1559 } 1560 1561 void 1562 sched_userret_slowpath(struct thread *td) 1563 { 1564 1565 thread_lock(td); 1566 td->td_priority = td->td_user_pri; 1567 td->td_base_pri = td->td_user_pri; 1568 thread_unlock(td); 1569 } 1570 1571 void 1572 sched_bind(struct thread *td, int cpu) 1573 { 1574 #ifdef SMP 1575 struct td_sched *ts = td_get_sched(td); 1576 #endif 1577 1578 THREAD_LOCK_ASSERT(td, MA_OWNED|MA_NOTRECURSED); 1579 KASSERT(td == curthread, ("sched_bind: can only bind curthread")); 1580 1581 td->td_flags |= TDF_BOUND; 1582 #ifdef SMP 1583 ts->ts_runq = &runq_pcpu[cpu]; 1584 if (PCPU_GET(cpuid) == cpu) 1585 return; 1586 1587 mi_switch(SW_VOL | SWT_BIND); 1588 thread_lock(td); 1589 #endif 1590 } 1591 1592 void 1593 sched_unbind(struct thread* td) 1594 { 1595 THREAD_LOCK_ASSERT(td, MA_OWNED); 1596 KASSERT(td == curthread, ("sched_unbind: can only bind curthread")); 1597 td->td_flags &= ~TDF_BOUND; 1598 } 1599 1600 int 1601 sched_is_bound(struct thread *td) 1602 { 1603 THREAD_LOCK_ASSERT(td, MA_OWNED); 1604 return (td->td_flags & TDF_BOUND); 1605 } 1606 1607 void 1608 sched_relinquish(struct thread *td) 1609 { 1610 thread_lock(td); 1611 mi_switch(SW_VOL | SWT_RELINQUISH); 1612 } 1613 1614 int 1615 sched_load(void) 1616 { 1617 return (sched_tdcnt); 1618 } 1619 1620 int 1621 sched_sizeof_proc(void) 1622 { 1623 return (sizeof(struct proc)); 1624 } 1625 1626 int 1627 sched_sizeof_thread(void) 1628 { 1629 return (sizeof(struct thread) + sizeof(struct td_sched)); 1630 } 1631 1632 fixpt_t 1633 sched_pctcpu(struct thread *td) 1634 { 1635 struct td_sched *ts; 1636 1637 THREAD_LOCK_ASSERT(td, MA_OWNED); 1638 ts = td_get_sched(td); 1639 return (ts->ts_pctcpu); 1640 } 1641 1642 #ifdef RACCT 1643 /* 1644 * Calculates the contribution to the thread cpu usage for the latest 1645 * (unfinished) second. 1646 */ 1647 fixpt_t 1648 sched_pctcpu_delta(struct thread *td) 1649 { 1650 struct td_sched *ts; 1651 fixpt_t delta; 1652 int realstathz; 1653 1654 THREAD_LOCK_ASSERT(td, MA_OWNED); 1655 ts = td_get_sched(td); 1656 delta = 0; 1657 realstathz = stathz ? stathz : hz; 1658 if (ts->ts_cpticks != 0) { 1659 #if (FSHIFT >= CCPU_SHIFT) 1660 delta = (realstathz == 100) 1661 ? ((fixpt_t) ts->ts_cpticks) << 1662 (FSHIFT - CCPU_SHIFT) : 1663 100 * (((fixpt_t) ts->ts_cpticks) 1664 << (FSHIFT - CCPU_SHIFT)) / realstathz; 1665 #else 1666 delta = ((FSCALE - ccpu) * 1667 (ts->ts_cpticks * 1668 FSCALE / realstathz)) >> FSHIFT; 1669 #endif 1670 } 1671 1672 return (delta); 1673 } 1674 #endif 1675 1676 u_int 1677 sched_estcpu(struct thread *td) 1678 { 1679 1680 return (td_get_sched(td)->ts_estcpu); 1681 } 1682 1683 /* 1684 * The actual idle process. 1685 */ 1686 void 1687 sched_idletd(void *dummy) 1688 { 1689 struct pcpuidlestat *stat; 1690 1691 THREAD_NO_SLEEPING(); 1692 stat = DPCPU_PTR(idlestat); 1693 for (;;) { 1694 mtx_assert(&Giant, MA_NOTOWNED); 1695 1696 while (!sched_runnable()) { 1697 cpu_idle(stat->idlecalls + stat->oldidlecalls > 64); 1698 stat->idlecalls++; 1699 } 1700 1701 mtx_lock_spin(&sched_lock); 1702 mi_switch(SW_VOL | SWT_IDLE); 1703 } 1704 } 1705 1706 static void 1707 sched_throw_tail(struct thread *td) 1708 { 1709 struct thread *newtd; 1710 1711 mtx_assert(&sched_lock, MA_OWNED); 1712 KASSERT(curthread->td_md.md_spinlock_count == 1, ("invalid count")); 1713 1714 newtd = choosethread(); 1715 1716 #ifdef HWT_HOOKS 1717 if (td) 1718 HWT_CALL_HOOK(td, HWT_SWITCH_OUT, NULL); 1719 HWT_CALL_HOOK(newtd, HWT_SWITCH_IN, NULL); 1720 #endif 1721 1722 cpu_throw(td, newtd); /* doesn't return */ 1723 } 1724 1725 /* 1726 * A CPU is entering for the first time. 1727 */ 1728 void 1729 sched_ap_entry(void) 1730 { 1731 1732 /* 1733 * Correct spinlock nesting. The idle thread context that we are 1734 * borrowing was created so that it would start out with a single 1735 * spin lock (sched_lock) held in fork_trampoline(). Since we've 1736 * explicitly acquired locks in this function, the nesting count 1737 * is now 2 rather than 1. Since we are nested, calling 1738 * spinlock_exit() will simply adjust the counts without allowing 1739 * spin lock using code to interrupt us. 1740 */ 1741 mtx_lock_spin(&sched_lock); 1742 spinlock_exit(); 1743 PCPU_SET(switchtime, cpu_ticks()); 1744 PCPU_SET(switchticks, ticks); 1745 1746 sched_throw_tail(NULL); 1747 } 1748 1749 /* 1750 * A thread is exiting. 1751 */ 1752 void 1753 sched_throw(struct thread *td) 1754 { 1755 1756 MPASS(td != NULL); 1757 MPASS(td->td_lock == &sched_lock); 1758 1759 lock_profile_release_lock(&sched_lock.lock_object, true); 1760 td->td_lastcpu = td->td_oncpu; 1761 td->td_oncpu = NOCPU; 1762 1763 sched_throw_tail(td); 1764 } 1765 1766 void 1767 sched_fork_exit(struct thread *td) 1768 { 1769 1770 /* 1771 * Finish setting up thread glue so that it begins execution in a 1772 * non-nested critical section with sched_lock held but not recursed. 1773 */ 1774 td->td_oncpu = PCPU_GET(cpuid); 1775 sched_lock.mtx_lock = (uintptr_t)td; 1776 lock_profile_obtain_lock_success(&sched_lock.lock_object, true, 1777 0, 0, __FILE__, __LINE__); 1778 THREAD_LOCK_ASSERT(td, MA_OWNED | MA_NOTRECURSED); 1779 1780 KTR_STATE1(KTR_SCHED, "thread", sched_tdname(td), "running", 1781 "prio:%d", td->td_priority); 1782 SDT_PROBE0(sched, , , on__cpu); 1783 } 1784 1785 char * 1786 sched_tdname(struct thread *td) 1787 { 1788 #ifdef KTR 1789 struct td_sched *ts; 1790 1791 ts = td_get_sched(td); 1792 if (ts->ts_name[0] == '\0') 1793 snprintf(ts->ts_name, sizeof(ts->ts_name), 1794 "%s tid %d", td->td_name, td->td_tid); 1795 return (ts->ts_name); 1796 #else 1797 return (td->td_name); 1798 #endif 1799 } 1800 1801 #ifdef KTR 1802 void 1803 sched_clear_tdname(struct thread *td) 1804 { 1805 struct td_sched *ts; 1806 1807 ts = td_get_sched(td); 1808 ts->ts_name[0] = '\0'; 1809 } 1810 #endif 1811 1812 void 1813 sched_affinity(struct thread *td) 1814 { 1815 #ifdef SMP 1816 struct td_sched *ts; 1817 int cpu; 1818 1819 THREAD_LOCK_ASSERT(td, MA_OWNED); 1820 1821 /* 1822 * Set the TSF_AFFINITY flag if there is at least one CPU this 1823 * thread can't run on. 1824 */ 1825 ts = td_get_sched(td); 1826 ts->ts_flags &= ~TSF_AFFINITY; 1827 CPU_FOREACH(cpu) { 1828 if (!THREAD_CAN_SCHED(td, cpu)) { 1829 ts->ts_flags |= TSF_AFFINITY; 1830 break; 1831 } 1832 } 1833 1834 /* 1835 * If this thread can run on all CPUs, nothing else to do. 1836 */ 1837 if (!(ts->ts_flags & TSF_AFFINITY)) 1838 return; 1839 1840 /* Pinned threads and bound threads should be left alone. */ 1841 if (td->td_pinned != 0 || td->td_flags & TDF_BOUND) 1842 return; 1843 1844 switch (TD_GET_STATE(td)) { 1845 case TDS_RUNQ: 1846 /* 1847 * If we are on a per-CPU runqueue that is in the set, 1848 * then nothing needs to be done. 1849 */ 1850 if (ts->ts_runq != &runq && 1851 THREAD_CAN_SCHED(td, ts->ts_runq - runq_pcpu)) 1852 return; 1853 1854 /* Put this thread on a valid per-CPU runqueue. */ 1855 sched_rem(td); 1856 sched_add(td, SRQ_HOLDTD | SRQ_BORING); 1857 break; 1858 case TDS_RUNNING: 1859 /* 1860 * See if our current CPU is in the set. If not, force a 1861 * context switch. 1862 */ 1863 if (THREAD_CAN_SCHED(td, td->td_oncpu)) 1864 return; 1865 1866 ast_sched_locked(td, TDA_SCHED); 1867 if (td != curthread) 1868 ipi_cpu(cpu, IPI_AST); 1869 break; 1870 default: 1871 break; 1872 } 1873 #endif 1874 } 1875