1 /*- 2 * Copyright (c) 1982, 1986, 1990, 1991, 1993 3 * The Regents of the University of California. All rights reserved. 4 * (c) UNIX System Laboratories, Inc. 5 * All or some portions of this file are derived from material licensed 6 * to the University of California by American Telephone and Telegraph 7 * Co. or Unix System Laboratories, Inc. and are reproduced herein with 8 * the permission of UNIX System Laboratories, Inc. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 4. Neither the name of the University nor the names of its contributors 19 * may be used to endorse or promote products derived from this software 20 * without specific prior written permission. 21 * 22 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 25 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 32 * SUCH DAMAGE. 33 */ 34 35 #include <sys/cdefs.h> 36 __FBSDID("$FreeBSD$"); 37 38 #include "opt_hwpmc_hooks.h" 39 #include "opt_sched.h" 40 #include "opt_kdtrace.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/sched.h> 53 #include <sys/sdt.h> 54 #include <sys/smp.h> 55 #include <sys/sysctl.h> 56 #include <sys/sx.h> 57 #include <sys/turnstile.h> 58 #include <sys/umtx.h> 59 #include <machine/pcb.h> 60 #include <machine/smp.h> 61 62 #ifdef HWPMC_HOOKS 63 #include <sys/pmckern.h> 64 #endif 65 66 #ifdef KDTRACE_HOOKS 67 #include <sys/dtrace_bsd.h> 68 int dtrace_vtime_active; 69 dtrace_vtime_switch_func_t dtrace_vtime_switch_func; 70 #endif 71 72 /* 73 * INVERSE_ESTCPU_WEIGHT is only suitable for statclock() frequencies in 74 * the range 100-256 Hz (approximately). 75 */ 76 #define ESTCPULIM(e) \ 77 min((e), INVERSE_ESTCPU_WEIGHT * (NICE_WEIGHT * (PRIO_MAX - PRIO_MIN) - \ 78 RQ_PPQ) + INVERSE_ESTCPU_WEIGHT - 1) 79 #ifdef SMP 80 #define INVERSE_ESTCPU_WEIGHT (8 * smp_cpus) 81 #else 82 #define INVERSE_ESTCPU_WEIGHT 8 /* 1 / (priorities per estcpu level). */ 83 #endif 84 #define NICE_WEIGHT 1 /* Priorities per nice level. */ 85 86 #define TS_NAME_LEN (MAXCOMLEN + sizeof(" td ") + sizeof(__XSTRING(UINT_MAX))) 87 88 /* 89 * The schedulable entity that runs a context. 90 * This is an extension to the thread structure and is tailored to 91 * the requirements of this scheduler 92 */ 93 struct td_sched { 94 fixpt_t ts_pctcpu; /* (j) %cpu during p_swtime. */ 95 int ts_cpticks; /* (j) Ticks of cpu time. */ 96 int ts_slptime; /* (j) Seconds !RUNNING. */ 97 int ts_slice; /* Remaining part of time slice. */ 98 int ts_flags; 99 struct runq *ts_runq; /* runq the thread is currently on */ 100 #ifdef KTR 101 char ts_name[TS_NAME_LEN]; 102 #endif 103 }; 104 105 /* flags kept in td_flags */ 106 #define TDF_DIDRUN TDF_SCHED0 /* thread actually ran. */ 107 #define TDF_BOUND TDF_SCHED1 /* Bound to one CPU. */ 108 #define TDF_SLICEEND TDF_SCHED2 /* Thread time slice is over. */ 109 110 /* flags kept in ts_flags */ 111 #define TSF_AFFINITY 0x0001 /* Has a non-"full" CPU set. */ 112 113 #define SKE_RUNQ_PCPU(ts) \ 114 ((ts)->ts_runq != 0 && (ts)->ts_runq != &runq) 115 116 #define THREAD_CAN_SCHED(td, cpu) \ 117 CPU_ISSET((cpu), &(td)->td_cpuset->cs_mask) 118 119 static struct td_sched td_sched0; 120 struct mtx sched_lock; 121 122 static int realstathz = 127; /* stathz is sometimes 0 and run off of hz. */ 123 static int sched_tdcnt; /* Total runnable threads in the system. */ 124 static int sched_slice = 12; /* Thread run time before rescheduling. */ 125 126 static void setup_runqs(void); 127 static void schedcpu(void); 128 static void schedcpu_thread(void); 129 static void sched_priority(struct thread *td, u_char prio); 130 static void sched_setup(void *dummy); 131 static void maybe_resched(struct thread *td); 132 static void updatepri(struct thread *td); 133 static void resetpriority(struct thread *td); 134 static void resetpriority_thread(struct thread *td); 135 #ifdef SMP 136 static int sched_pickcpu(struct thread *td); 137 static int forward_wakeup(int cpunum); 138 static void kick_other_cpu(int pri, int cpuid); 139 #endif 140 141 static struct kproc_desc sched_kp = { 142 "schedcpu", 143 schedcpu_thread, 144 NULL 145 }; 146 SYSINIT(schedcpu, SI_SUB_RUN_SCHEDULER, SI_ORDER_FIRST, kproc_start, 147 &sched_kp); 148 SYSINIT(sched_setup, SI_SUB_RUN_QUEUE, SI_ORDER_FIRST, sched_setup, NULL); 149 150 static void sched_initticks(void *dummy); 151 SYSINIT(sched_initticks, SI_SUB_CLOCKS, SI_ORDER_THIRD, sched_initticks, 152 NULL); 153 154 /* 155 * Global run queue. 156 */ 157 static struct runq runq; 158 159 #ifdef SMP 160 /* 161 * Per-CPU run queues 162 */ 163 static struct runq runq_pcpu[MAXCPU]; 164 long runq_length[MAXCPU]; 165 166 static cpuset_t idle_cpus_mask; 167 #endif 168 169 struct pcpuidlestat { 170 u_int idlecalls; 171 u_int oldidlecalls; 172 }; 173 static DPCPU_DEFINE(struct pcpuidlestat, idlestat); 174 175 static void 176 setup_runqs(void) 177 { 178 #ifdef SMP 179 int i; 180 181 for (i = 0; i < MAXCPU; ++i) 182 runq_init(&runq_pcpu[i]); 183 #endif 184 185 runq_init(&runq); 186 } 187 188 static int 189 sysctl_kern_quantum(SYSCTL_HANDLER_ARGS) 190 { 191 int error, new_val, period; 192 193 period = 1000000 / realstathz; 194 new_val = period * sched_slice; 195 error = sysctl_handle_int(oidp, &new_val, 0, req); 196 if (error != 0 || req->newptr == NULL) 197 return (error); 198 if (new_val <= 0) 199 return (EINVAL); 200 sched_slice = imax(1, (new_val + period / 2) / period); 201 hogticks = imax(1, (2 * hz * sched_slice + realstathz / 2) / 202 realstathz); 203 return (0); 204 } 205 206 SYSCTL_NODE(_kern, OID_AUTO, sched, CTLFLAG_RD, 0, "Scheduler"); 207 208 SYSCTL_STRING(_kern_sched, OID_AUTO, name, CTLFLAG_RD, "4BSD", 0, 209 "Scheduler name"); 210 SYSCTL_PROC(_kern_sched, OID_AUTO, quantum, CTLTYPE_INT | CTLFLAG_RW, 211 NULL, 0, sysctl_kern_quantum, "I", 212 "Quantum for timeshare threads in microseconds"); 213 SYSCTL_INT(_kern_sched, OID_AUTO, slice, CTLFLAG_RW, &sched_slice, 0, 214 "Quantum for timeshare threads in stathz ticks"); 215 #ifdef SMP 216 /* Enable forwarding of wakeups to all other cpus */ 217 static SYSCTL_NODE(_kern_sched, OID_AUTO, ipiwakeup, CTLFLAG_RD, NULL, 218 "Kernel SMP"); 219 220 static int runq_fuzz = 1; 221 SYSCTL_INT(_kern_sched, OID_AUTO, runq_fuzz, CTLFLAG_RW, &runq_fuzz, 0, ""); 222 223 static int forward_wakeup_enabled = 1; 224 SYSCTL_INT(_kern_sched_ipiwakeup, OID_AUTO, enabled, CTLFLAG_RW, 225 &forward_wakeup_enabled, 0, 226 "Forwarding of wakeup to idle CPUs"); 227 228 static int forward_wakeups_requested = 0; 229 SYSCTL_INT(_kern_sched_ipiwakeup, OID_AUTO, requested, CTLFLAG_RD, 230 &forward_wakeups_requested, 0, 231 "Requests for Forwarding of wakeup to idle CPUs"); 232 233 static int forward_wakeups_delivered = 0; 234 SYSCTL_INT(_kern_sched_ipiwakeup, OID_AUTO, delivered, CTLFLAG_RD, 235 &forward_wakeups_delivered, 0, 236 "Completed Forwarding of wakeup to idle CPUs"); 237 238 static int forward_wakeup_use_mask = 1; 239 SYSCTL_INT(_kern_sched_ipiwakeup, OID_AUTO, usemask, CTLFLAG_RW, 240 &forward_wakeup_use_mask, 0, 241 "Use the mask of idle cpus"); 242 243 static int forward_wakeup_use_loop = 0; 244 SYSCTL_INT(_kern_sched_ipiwakeup, OID_AUTO, useloop, CTLFLAG_RW, 245 &forward_wakeup_use_loop, 0, 246 "Use a loop to find idle cpus"); 247 248 #endif 249 #if 0 250 static int sched_followon = 0; 251 SYSCTL_INT(_kern_sched, OID_AUTO, followon, CTLFLAG_RW, 252 &sched_followon, 0, 253 "allow threads to share a quantum"); 254 #endif 255 256 SDT_PROVIDER_DEFINE(sched); 257 258 SDT_PROBE_DEFINE3(sched, , , change_pri, change-pri, "struct thread *", 259 "struct proc *", "uint8_t"); 260 SDT_PROBE_DEFINE3(sched, , , dequeue, dequeue, "struct thread *", 261 "struct proc *", "void *"); 262 SDT_PROBE_DEFINE4(sched, , , enqueue, enqueue, "struct thread *", 263 "struct proc *", "void *", "int"); 264 SDT_PROBE_DEFINE4(sched, , , lend_pri, lend-pri, "struct thread *", 265 "struct proc *", "uint8_t", "struct thread *"); 266 SDT_PROBE_DEFINE2(sched, , , load_change, load-change, "int", "int"); 267 SDT_PROBE_DEFINE2(sched, , , off_cpu, off-cpu, "struct thread *", 268 "struct proc *"); 269 SDT_PROBE_DEFINE(sched, , , on_cpu, on-cpu); 270 SDT_PROBE_DEFINE(sched, , , remain_cpu, remain-cpu); 271 SDT_PROBE_DEFINE2(sched, , , surrender, surrender, "struct thread *", 272 "struct proc *"); 273 274 static __inline void 275 sched_load_add(void) 276 { 277 278 sched_tdcnt++; 279 KTR_COUNTER0(KTR_SCHED, "load", "global load", sched_tdcnt); 280 SDT_PROBE2(sched, , , load_change, NOCPU, sched_tdcnt); 281 } 282 283 static __inline void 284 sched_load_rem(void) 285 { 286 287 sched_tdcnt--; 288 KTR_COUNTER0(KTR_SCHED, "load", "global load", sched_tdcnt); 289 SDT_PROBE2(sched, , , load_change, NOCPU, sched_tdcnt); 290 } 291 /* 292 * Arrange to reschedule if necessary, taking the priorities and 293 * schedulers into account. 294 */ 295 static void 296 maybe_resched(struct thread *td) 297 { 298 299 THREAD_LOCK_ASSERT(td, MA_OWNED); 300 if (td->td_priority < curthread->td_priority) 301 curthread->td_flags |= TDF_NEEDRESCHED; 302 } 303 304 /* 305 * This function is called when a thread is about to be put on run queue 306 * because it has been made runnable or its priority has been adjusted. It 307 * determines if the new thread should be immediately preempted to. If so, 308 * it switches to it and eventually returns true. If not, it returns false 309 * so that the caller may place the thread on an appropriate run queue. 310 */ 311 int 312 maybe_preempt(struct thread *td) 313 { 314 #ifdef PREEMPTION 315 struct thread *ctd; 316 int cpri, pri; 317 318 /* 319 * The new thread should not preempt the current thread if any of the 320 * following conditions are true: 321 * 322 * - The kernel is in the throes of crashing (panicstr). 323 * - The current thread has a higher (numerically lower) or 324 * equivalent priority. Note that this prevents curthread from 325 * trying to preempt to itself. 326 * - It is too early in the boot for context switches (cold is set). 327 * - The current thread has an inhibitor set or is in the process of 328 * exiting. In this case, the current thread is about to switch 329 * out anyways, so there's no point in preempting. If we did, 330 * the current thread would not be properly resumed as well, so 331 * just avoid that whole landmine. 332 * - If the new thread's priority is not a realtime priority and 333 * the current thread's priority is not an idle priority and 334 * FULL_PREEMPTION is disabled. 335 * 336 * If all of these conditions are false, but the current thread is in 337 * a nested critical section, then we have to defer the preemption 338 * until we exit the critical section. Otherwise, switch immediately 339 * to the new thread. 340 */ 341 ctd = curthread; 342 THREAD_LOCK_ASSERT(td, MA_OWNED); 343 KASSERT((td->td_inhibitors == 0), 344 ("maybe_preempt: trying to run inhibited thread")); 345 pri = td->td_priority; 346 cpri = ctd->td_priority; 347 if (panicstr != NULL || pri >= cpri || cold /* || dumping */ || 348 TD_IS_INHIBITED(ctd)) 349 return (0); 350 #ifndef FULL_PREEMPTION 351 if (pri > PRI_MAX_ITHD && cpri < PRI_MIN_IDLE) 352 return (0); 353 #endif 354 355 if (ctd->td_critnest > 1) { 356 CTR1(KTR_PROC, "maybe_preempt: in critical section %d", 357 ctd->td_critnest); 358 ctd->td_owepreempt = 1; 359 return (0); 360 } 361 /* 362 * Thread is runnable but not yet put on system run queue. 363 */ 364 MPASS(ctd->td_lock == td->td_lock); 365 MPASS(TD_ON_RUNQ(td)); 366 TD_SET_RUNNING(td); 367 CTR3(KTR_PROC, "preempting to thread %p (pid %d, %s)\n", td, 368 td->td_proc->p_pid, td->td_name); 369 mi_switch(SW_INVOL | SW_PREEMPT | SWT_PREEMPT, td); 370 /* 371 * td's lock pointer may have changed. We have to return with it 372 * locked. 373 */ 374 spinlock_enter(); 375 thread_unlock(ctd); 376 thread_lock(td); 377 spinlock_exit(); 378 return (1); 379 #else 380 return (0); 381 #endif 382 } 383 384 /* 385 * Constants for digital decay and forget: 386 * 90% of (td_estcpu) usage in 5 * loadav time 387 * 95% of (ts_pctcpu) usage in 60 seconds (load insensitive) 388 * Note that, as ps(1) mentions, this can let percentages 389 * total over 100% (I've seen 137.9% for 3 processes). 390 * 391 * Note that schedclock() updates td_estcpu and p_cpticks asynchronously. 392 * 393 * We wish to decay away 90% of td_estcpu in (5 * loadavg) seconds. 394 * That is, the system wants to compute a value of decay such 395 * that the following for loop: 396 * for (i = 0; i < (5 * loadavg); i++) 397 * td_estcpu *= decay; 398 * will compute 399 * td_estcpu *= 0.1; 400 * for all values of loadavg: 401 * 402 * Mathematically this loop can be expressed by saying: 403 * decay ** (5 * loadavg) ~= .1 404 * 405 * The system computes decay as: 406 * decay = (2 * loadavg) / (2 * loadavg + 1) 407 * 408 * We wish to prove that the system's computation of decay 409 * will always fulfill the equation: 410 * decay ** (5 * loadavg) ~= .1 411 * 412 * If we compute b as: 413 * b = 2 * loadavg 414 * then 415 * decay = b / (b + 1) 416 * 417 * We now need to prove two things: 418 * 1) Given factor ** (5 * loadavg) ~= .1, prove factor == b/(b+1) 419 * 2) Given b/(b+1) ** power ~= .1, prove power == (5 * loadavg) 420 * 421 * Facts: 422 * For x close to zero, exp(x) =~ 1 + x, since 423 * exp(x) = 0! + x**1/1! + x**2/2! + ... . 424 * therefore exp(-1/b) =~ 1 - (1/b) = (b-1)/b. 425 * For x close to zero, ln(1+x) =~ x, since 426 * ln(1+x) = x - x**2/2 + x**3/3 - ... -1 < x < 1 427 * therefore ln(b/(b+1)) = ln(1 - 1/(b+1)) =~ -1/(b+1). 428 * ln(.1) =~ -2.30 429 * 430 * Proof of (1): 431 * Solve (factor)**(power) =~ .1 given power (5*loadav): 432 * solving for factor, 433 * ln(factor) =~ (-2.30/5*loadav), or 434 * factor =~ exp(-1/((5/2.30)*loadav)) =~ exp(-1/(2*loadav)) = 435 * exp(-1/b) =~ (b-1)/b =~ b/(b+1). QED 436 * 437 * Proof of (2): 438 * Solve (factor)**(power) =~ .1 given factor == (b/(b+1)): 439 * solving for power, 440 * power*ln(b/(b+1)) =~ -2.30, or 441 * power =~ 2.3 * (b + 1) = 4.6*loadav + 2.3 =~ 5*loadav. QED 442 * 443 * Actual power values for the implemented algorithm are as follows: 444 * loadav: 1 2 3 4 445 * power: 5.68 10.32 14.94 19.55 446 */ 447 448 /* calculations for digital decay to forget 90% of usage in 5*loadav sec */ 449 #define loadfactor(loadav) (2 * (loadav)) 450 #define decay_cpu(loadfac, cpu) (((loadfac) * (cpu)) / ((loadfac) + FSCALE)) 451 452 /* decay 95% of `ts_pctcpu' in 60 seconds; see CCPU_SHIFT before changing */ 453 static fixpt_t ccpu = 0.95122942450071400909 * FSCALE; /* exp(-1/20) */ 454 SYSCTL_UINT(_kern, OID_AUTO, ccpu, CTLFLAG_RD, &ccpu, 0, ""); 455 456 /* 457 * If `ccpu' is not equal to `exp(-1/20)' and you still want to use the 458 * faster/more-accurate formula, you'll have to estimate CCPU_SHIFT below 459 * and possibly adjust FSHIFT in "param.h" so that (FSHIFT >= CCPU_SHIFT). 460 * 461 * To estimate CCPU_SHIFT for exp(-1/20), the following formula was used: 462 * 1 - exp(-1/20) ~= 0.0487 ~= 0.0488 == 1 (fixed pt, *11* bits). 463 * 464 * If you don't want to bother with the faster/more-accurate formula, you 465 * can set CCPU_SHIFT to (FSHIFT + 1) which will use a slower/less-accurate 466 * (more general) method of calculating the %age of CPU used by a process. 467 */ 468 #define CCPU_SHIFT 11 469 470 /* 471 * Recompute process priorities, every hz ticks. 472 * MP-safe, called without the Giant mutex. 473 */ 474 /* ARGSUSED */ 475 static void 476 schedcpu(void) 477 { 478 register fixpt_t loadfac = loadfactor(averunnable.ldavg[0]); 479 struct thread *td; 480 struct proc *p; 481 struct td_sched *ts; 482 int awake; 483 484 sx_slock(&allproc_lock); 485 FOREACH_PROC_IN_SYSTEM(p) { 486 PROC_LOCK(p); 487 if (p->p_state == PRS_NEW) { 488 PROC_UNLOCK(p); 489 continue; 490 } 491 FOREACH_THREAD_IN_PROC(p, td) { 492 awake = 0; 493 thread_lock(td); 494 ts = td->td_sched; 495 /* 496 * Increment sleep time (if sleeping). We 497 * ignore overflow, as above. 498 */ 499 /* 500 * The td_sched slptimes are not touched in wakeup 501 * because the thread may not HAVE everything in 502 * memory? XXX I think this is out of date. 503 */ 504 if (TD_ON_RUNQ(td)) { 505 awake = 1; 506 td->td_flags &= ~TDF_DIDRUN; 507 } else if (TD_IS_RUNNING(td)) { 508 awake = 1; 509 /* Do not clear TDF_DIDRUN */ 510 } else if (td->td_flags & TDF_DIDRUN) { 511 awake = 1; 512 td->td_flags &= ~TDF_DIDRUN; 513 } 514 515 /* 516 * ts_pctcpu is only for ps and ttyinfo(). 517 */ 518 ts->ts_pctcpu = (ts->ts_pctcpu * ccpu) >> FSHIFT; 519 /* 520 * If the td_sched has been idle the entire second, 521 * stop recalculating its priority until 522 * it wakes up. 523 */ 524 if (ts->ts_cpticks != 0) { 525 #if (FSHIFT >= CCPU_SHIFT) 526 ts->ts_pctcpu += (realstathz == 100) 527 ? ((fixpt_t) ts->ts_cpticks) << 528 (FSHIFT - CCPU_SHIFT) : 529 100 * (((fixpt_t) ts->ts_cpticks) 530 << (FSHIFT - CCPU_SHIFT)) / realstathz; 531 #else 532 ts->ts_pctcpu += ((FSCALE - ccpu) * 533 (ts->ts_cpticks * 534 FSCALE / realstathz)) >> FSHIFT; 535 #endif 536 ts->ts_cpticks = 0; 537 } 538 /* 539 * If there are ANY running threads in this process, 540 * then don't count it as sleeping. 541 * XXX: this is broken. 542 */ 543 if (awake) { 544 if (ts->ts_slptime > 1) { 545 /* 546 * In an ideal world, this should not 547 * happen, because whoever woke us 548 * up from the long sleep should have 549 * unwound the slptime and reset our 550 * priority before we run at the stale 551 * priority. Should KASSERT at some 552 * point when all the cases are fixed. 553 */ 554 updatepri(td); 555 } 556 ts->ts_slptime = 0; 557 } else 558 ts->ts_slptime++; 559 if (ts->ts_slptime > 1) { 560 thread_unlock(td); 561 continue; 562 } 563 td->td_estcpu = decay_cpu(loadfac, td->td_estcpu); 564 resetpriority(td); 565 resetpriority_thread(td); 566 thread_unlock(td); 567 } 568 PROC_UNLOCK(p); 569 } 570 sx_sunlock(&allproc_lock); 571 } 572 573 /* 574 * Main loop for a kthread that executes schedcpu once a second. 575 */ 576 static void 577 schedcpu_thread(void) 578 { 579 580 for (;;) { 581 schedcpu(); 582 pause("-", hz); 583 } 584 } 585 586 /* 587 * Recalculate the priority of a process after it has slept for a while. 588 * For all load averages >= 1 and max td_estcpu of 255, sleeping for at 589 * least six times the loadfactor will decay td_estcpu to zero. 590 */ 591 static void 592 updatepri(struct thread *td) 593 { 594 struct td_sched *ts; 595 fixpt_t loadfac; 596 unsigned int newcpu; 597 598 ts = td->td_sched; 599 loadfac = loadfactor(averunnable.ldavg[0]); 600 if (ts->ts_slptime > 5 * loadfac) 601 td->td_estcpu = 0; 602 else { 603 newcpu = td->td_estcpu; 604 ts->ts_slptime--; /* was incremented in schedcpu() */ 605 while (newcpu && --ts->ts_slptime) 606 newcpu = decay_cpu(loadfac, newcpu); 607 td->td_estcpu = newcpu; 608 } 609 } 610 611 /* 612 * Compute the priority of a process when running in user mode. 613 * Arrange to reschedule if the resulting priority is better 614 * than that of the current process. 615 */ 616 static void 617 resetpriority(struct thread *td) 618 { 619 register unsigned int newpriority; 620 621 if (td->td_pri_class == PRI_TIMESHARE) { 622 newpriority = PUSER + td->td_estcpu / INVERSE_ESTCPU_WEIGHT + 623 NICE_WEIGHT * (td->td_proc->p_nice - PRIO_MIN); 624 newpriority = min(max(newpriority, PRI_MIN_TIMESHARE), 625 PRI_MAX_TIMESHARE); 626 sched_user_prio(td, newpriority); 627 } 628 } 629 630 /* 631 * Update the thread's priority when the associated process's user 632 * priority changes. 633 */ 634 static void 635 resetpriority_thread(struct thread *td) 636 { 637 638 /* Only change threads with a time sharing user priority. */ 639 if (td->td_priority < PRI_MIN_TIMESHARE || 640 td->td_priority > PRI_MAX_TIMESHARE) 641 return; 642 643 /* XXX the whole needresched thing is broken, but not silly. */ 644 maybe_resched(td); 645 646 sched_prio(td, td->td_user_pri); 647 } 648 649 /* ARGSUSED */ 650 static void 651 sched_setup(void *dummy) 652 { 653 654 setup_runqs(); 655 656 /* Account for thread0. */ 657 sched_load_add(); 658 } 659 660 /* 661 * This routine determines time constants after stathz and hz are setup. 662 */ 663 static void 664 sched_initticks(void *dummy) 665 { 666 667 realstathz = stathz ? stathz : hz; 668 sched_slice = realstathz / 10; /* ~100ms */ 669 hogticks = imax(1, (2 * hz * sched_slice + realstathz / 2) / 670 realstathz); 671 } 672 673 /* External interfaces start here */ 674 675 /* 676 * Very early in the boot some setup of scheduler-specific 677 * parts of proc0 and of some scheduler resources needs to be done. 678 * Called from: 679 * proc0_init() 680 */ 681 void 682 schedinit(void) 683 { 684 /* 685 * Set up the scheduler specific parts of proc0. 686 */ 687 proc0.p_sched = NULL; /* XXX */ 688 thread0.td_sched = &td_sched0; 689 thread0.td_lock = &sched_lock; 690 td_sched0.ts_slice = sched_slice; 691 mtx_init(&sched_lock, "sched lock", NULL, MTX_SPIN | MTX_RECURSE); 692 } 693 694 int 695 sched_runnable(void) 696 { 697 #ifdef SMP 698 return runq_check(&runq) + runq_check(&runq_pcpu[PCPU_GET(cpuid)]); 699 #else 700 return runq_check(&runq); 701 #endif 702 } 703 704 int 705 sched_rr_interval(void) 706 { 707 708 /* Convert sched_slice from stathz to hz. */ 709 return (imax(1, (sched_slice * hz + realstathz / 2) / realstathz)); 710 } 711 712 /* 713 * We adjust the priority of the current process. The priority of 714 * a process gets worse as it accumulates CPU time. The cpu usage 715 * estimator (td_estcpu) is increased here. resetpriority() will 716 * compute a different priority each time td_estcpu increases by 717 * INVERSE_ESTCPU_WEIGHT 718 * (until MAXPRI is reached). The cpu usage estimator ramps up 719 * quite quickly when the process is running (linearly), and decays 720 * away exponentially, at a rate which is proportionally slower when 721 * the system is busy. The basic principle is that the system will 722 * 90% forget that the process used a lot of CPU time in 5 * loadav 723 * seconds. This causes the system to favor processes which haven't 724 * run much recently, and to round-robin among other processes. 725 */ 726 void 727 sched_clock(struct thread *td) 728 { 729 struct pcpuidlestat *stat; 730 struct td_sched *ts; 731 732 THREAD_LOCK_ASSERT(td, MA_OWNED); 733 ts = td->td_sched; 734 735 ts->ts_cpticks++; 736 td->td_estcpu = ESTCPULIM(td->td_estcpu + 1); 737 if ((td->td_estcpu % INVERSE_ESTCPU_WEIGHT) == 0) { 738 resetpriority(td); 739 resetpriority_thread(td); 740 } 741 742 /* 743 * Force a context switch if the current thread has used up a full 744 * time slice (default is 100ms). 745 */ 746 if (!TD_IS_IDLETHREAD(td) && --ts->ts_slice <= 0) { 747 ts->ts_slice = sched_slice; 748 td->td_flags |= TDF_NEEDRESCHED | TDF_SLICEEND; 749 } 750 751 stat = DPCPU_PTR(idlestat); 752 stat->oldidlecalls = stat->idlecalls; 753 stat->idlecalls = 0; 754 } 755 756 /* 757 * Charge child's scheduling CPU usage to parent. 758 */ 759 void 760 sched_exit(struct proc *p, struct thread *td) 761 { 762 763 KTR_STATE1(KTR_SCHED, "thread", sched_tdname(td), "proc exit", 764 "prio:%d", td->td_priority); 765 766 PROC_LOCK_ASSERT(p, MA_OWNED); 767 sched_exit_thread(FIRST_THREAD_IN_PROC(p), td); 768 } 769 770 void 771 sched_exit_thread(struct thread *td, struct thread *child) 772 { 773 774 KTR_STATE1(KTR_SCHED, "thread", sched_tdname(child), "exit", 775 "prio:%d", child->td_priority); 776 thread_lock(td); 777 td->td_estcpu = ESTCPULIM(td->td_estcpu + child->td_estcpu); 778 thread_unlock(td); 779 thread_lock(child); 780 if ((child->td_flags & TDF_NOLOAD) == 0) 781 sched_load_rem(); 782 thread_unlock(child); 783 } 784 785 void 786 sched_fork(struct thread *td, struct thread *childtd) 787 { 788 sched_fork_thread(td, childtd); 789 } 790 791 void 792 sched_fork_thread(struct thread *td, struct thread *childtd) 793 { 794 struct td_sched *ts; 795 796 childtd->td_estcpu = td->td_estcpu; 797 childtd->td_lock = &sched_lock; 798 childtd->td_cpuset = cpuset_ref(td->td_cpuset); 799 childtd->td_priority = childtd->td_base_pri; 800 ts = childtd->td_sched; 801 bzero(ts, sizeof(*ts)); 802 ts->ts_flags |= (td->td_sched->ts_flags & TSF_AFFINITY); 803 ts->ts_slice = 1; 804 } 805 806 void 807 sched_nice(struct proc *p, int nice) 808 { 809 struct thread *td; 810 811 PROC_LOCK_ASSERT(p, MA_OWNED); 812 p->p_nice = nice; 813 FOREACH_THREAD_IN_PROC(p, td) { 814 thread_lock(td); 815 resetpriority(td); 816 resetpriority_thread(td); 817 thread_unlock(td); 818 } 819 } 820 821 void 822 sched_class(struct thread *td, int class) 823 { 824 THREAD_LOCK_ASSERT(td, MA_OWNED); 825 td->td_pri_class = class; 826 } 827 828 /* 829 * Adjust the priority of a thread. 830 */ 831 static void 832 sched_priority(struct thread *td, u_char prio) 833 { 834 835 836 KTR_POINT3(KTR_SCHED, "thread", sched_tdname(td), "priority change", 837 "prio:%d", td->td_priority, "new prio:%d", prio, KTR_ATTR_LINKED, 838 sched_tdname(curthread)); 839 SDT_PROBE3(sched, , , change_pri, td, td->td_proc, prio); 840 if (td != curthread && prio > td->td_priority) { 841 KTR_POINT3(KTR_SCHED, "thread", sched_tdname(curthread), 842 "lend prio", "prio:%d", td->td_priority, "new prio:%d", 843 prio, KTR_ATTR_LINKED, sched_tdname(td)); 844 SDT_PROBE4(sched, , , lend_pri, td, td->td_proc, prio, 845 curthread); 846 } 847 THREAD_LOCK_ASSERT(td, MA_OWNED); 848 if (td->td_priority == prio) 849 return; 850 td->td_priority = prio; 851 if (TD_ON_RUNQ(td) && td->td_rqindex != (prio / RQ_PPQ)) { 852 sched_rem(td); 853 sched_add(td, SRQ_BORING); 854 } 855 } 856 857 /* 858 * Update a thread's priority when it is lent another thread's 859 * priority. 860 */ 861 void 862 sched_lend_prio(struct thread *td, u_char prio) 863 { 864 865 td->td_flags |= TDF_BORROWING; 866 sched_priority(td, prio); 867 } 868 869 /* 870 * Restore a thread's priority when priority propagation is 871 * over. The prio argument is the minimum priority the thread 872 * needs to have to satisfy other possible priority lending 873 * requests. If the thread's regulary priority is less 874 * important than prio the thread will keep a priority boost 875 * of prio. 876 */ 877 void 878 sched_unlend_prio(struct thread *td, u_char prio) 879 { 880 u_char base_pri; 881 882 if (td->td_base_pri >= PRI_MIN_TIMESHARE && 883 td->td_base_pri <= PRI_MAX_TIMESHARE) 884 base_pri = td->td_user_pri; 885 else 886 base_pri = td->td_base_pri; 887 if (prio >= base_pri) { 888 td->td_flags &= ~TDF_BORROWING; 889 sched_prio(td, base_pri); 890 } else 891 sched_lend_prio(td, prio); 892 } 893 894 void 895 sched_prio(struct thread *td, u_char prio) 896 { 897 u_char oldprio; 898 899 /* First, update the base priority. */ 900 td->td_base_pri = prio; 901 902 /* 903 * If the thread is borrowing another thread's priority, don't ever 904 * lower the priority. 905 */ 906 if (td->td_flags & TDF_BORROWING && td->td_priority < prio) 907 return; 908 909 /* Change the real priority. */ 910 oldprio = td->td_priority; 911 sched_priority(td, prio); 912 913 /* 914 * If the thread is on a turnstile, then let the turnstile update 915 * its state. 916 */ 917 if (TD_ON_LOCK(td) && oldprio != prio) 918 turnstile_adjust(td, oldprio); 919 } 920 921 void 922 sched_user_prio(struct thread *td, u_char prio) 923 { 924 925 THREAD_LOCK_ASSERT(td, MA_OWNED); 926 td->td_base_user_pri = prio; 927 if (td->td_lend_user_pri <= prio) 928 return; 929 td->td_user_pri = prio; 930 } 931 932 void 933 sched_lend_user_prio(struct thread *td, u_char prio) 934 { 935 936 THREAD_LOCK_ASSERT(td, MA_OWNED); 937 td->td_lend_user_pri = prio; 938 td->td_user_pri = min(prio, td->td_base_user_pri); 939 if (td->td_priority > td->td_user_pri) 940 sched_prio(td, td->td_user_pri); 941 else if (td->td_priority != td->td_user_pri) 942 td->td_flags |= TDF_NEEDRESCHED; 943 } 944 945 void 946 sched_sleep(struct thread *td, int pri) 947 { 948 949 THREAD_LOCK_ASSERT(td, MA_OWNED); 950 td->td_slptick = ticks; 951 td->td_sched->ts_slptime = 0; 952 if (pri != 0 && PRI_BASE(td->td_pri_class) == PRI_TIMESHARE) 953 sched_prio(td, pri); 954 if (TD_IS_SUSPENDED(td) || pri >= PSOCK) 955 td->td_flags |= TDF_CANSWAP; 956 } 957 958 void 959 sched_switch(struct thread *td, struct thread *newtd, int flags) 960 { 961 struct mtx *tmtx; 962 struct td_sched *ts; 963 struct proc *p; 964 int preempted; 965 966 tmtx = NULL; 967 ts = td->td_sched; 968 p = td->td_proc; 969 970 THREAD_LOCK_ASSERT(td, MA_OWNED); 971 972 /* 973 * Switch to the sched lock to fix things up and pick 974 * a new thread. 975 * Block the td_lock in order to avoid breaking the critical path. 976 */ 977 if (td->td_lock != &sched_lock) { 978 mtx_lock_spin(&sched_lock); 979 tmtx = thread_lock_block(td); 980 } 981 982 if ((td->td_flags & TDF_NOLOAD) == 0) 983 sched_load_rem(); 984 985 td->td_lastcpu = td->td_oncpu; 986 preempted = !(td->td_flags & TDF_SLICEEND); 987 td->td_flags &= ~(TDF_NEEDRESCHED | TDF_SLICEEND); 988 td->td_owepreempt = 0; 989 td->td_oncpu = NOCPU; 990 991 /* 992 * At the last moment, if this thread is still marked RUNNING, 993 * then put it back on the run queue as it has not been suspended 994 * or stopped or any thing else similar. We never put the idle 995 * threads on the run queue, however. 996 */ 997 if (td->td_flags & TDF_IDLETD) { 998 TD_SET_CAN_RUN(td); 999 #ifdef SMP 1000 CPU_CLR(PCPU_GET(cpuid), &idle_cpus_mask); 1001 #endif 1002 } else { 1003 if (TD_IS_RUNNING(td)) { 1004 /* Put us back on the run queue. */ 1005 sched_add(td, preempted ? 1006 SRQ_OURSELF|SRQ_YIELDING|SRQ_PREEMPTED : 1007 SRQ_OURSELF|SRQ_YIELDING); 1008 } 1009 } 1010 if (newtd) { 1011 /* 1012 * The thread we are about to run needs to be counted 1013 * as if it had been added to the run queue and selected. 1014 * It came from: 1015 * * A preemption 1016 * * An upcall 1017 * * A followon 1018 */ 1019 KASSERT((newtd->td_inhibitors == 0), 1020 ("trying to run inhibited thread")); 1021 newtd->td_flags |= TDF_DIDRUN; 1022 TD_SET_RUNNING(newtd); 1023 if ((newtd->td_flags & TDF_NOLOAD) == 0) 1024 sched_load_add(); 1025 } else { 1026 newtd = choosethread(); 1027 MPASS(newtd->td_lock == &sched_lock); 1028 } 1029 1030 if (td != newtd) { 1031 #ifdef HWPMC_HOOKS 1032 if (PMC_PROC_IS_USING_PMCS(td->td_proc)) 1033 PMC_SWITCH_CONTEXT(td, PMC_FN_CSW_OUT); 1034 #endif 1035 1036 SDT_PROBE2(sched, , , off_cpu, td, td->td_proc); 1037 1038 /* I feel sleepy */ 1039 lock_profile_release_lock(&sched_lock.lock_object); 1040 #ifdef KDTRACE_HOOKS 1041 /* 1042 * If DTrace has set the active vtime enum to anything 1043 * other than INACTIVE (0), then it should have set the 1044 * function to call. 1045 */ 1046 if (dtrace_vtime_active) 1047 (*dtrace_vtime_switch_func)(newtd); 1048 #endif 1049 1050 cpu_switch(td, newtd, tmtx != NULL ? tmtx : td->td_lock); 1051 lock_profile_obtain_lock_success(&sched_lock.lock_object, 1052 0, 0, __FILE__, __LINE__); 1053 /* 1054 * Where am I? What year is it? 1055 * We are in the same thread that went to sleep above, 1056 * but any amount of time may have passed. All our context 1057 * will still be available as will local variables. 1058 * PCPU values however may have changed as we may have 1059 * changed CPU so don't trust cached values of them. 1060 * New threads will go to fork_exit() instead of here 1061 * so if you change things here you may need to change 1062 * things there too. 1063 * 1064 * If the thread above was exiting it will never wake 1065 * up again here, so either it has saved everything it 1066 * needed to, or the thread_wait() or wait() will 1067 * need to reap it. 1068 */ 1069 1070 SDT_PROBE0(sched, , , on_cpu); 1071 #ifdef HWPMC_HOOKS 1072 if (PMC_PROC_IS_USING_PMCS(td->td_proc)) 1073 PMC_SWITCH_CONTEXT(td, PMC_FN_CSW_IN); 1074 #endif 1075 } else 1076 SDT_PROBE0(sched, , , remain_cpu); 1077 1078 #ifdef SMP 1079 if (td->td_flags & TDF_IDLETD) 1080 CPU_SET(PCPU_GET(cpuid), &idle_cpus_mask); 1081 #endif 1082 sched_lock.mtx_lock = (uintptr_t)td; 1083 td->td_oncpu = PCPU_GET(cpuid); 1084 MPASS(td->td_lock == &sched_lock); 1085 } 1086 1087 void 1088 sched_wakeup(struct thread *td) 1089 { 1090 struct td_sched *ts; 1091 1092 THREAD_LOCK_ASSERT(td, MA_OWNED); 1093 ts = td->td_sched; 1094 td->td_flags &= ~TDF_CANSWAP; 1095 if (ts->ts_slptime > 1) { 1096 updatepri(td); 1097 resetpriority(td); 1098 } 1099 td->td_slptick = 0; 1100 ts->ts_slptime = 0; 1101 ts->ts_slice = sched_slice; 1102 sched_add(td, SRQ_BORING); 1103 } 1104 1105 #ifdef SMP 1106 static int 1107 forward_wakeup(int cpunum) 1108 { 1109 struct pcpu *pc; 1110 cpuset_t dontuse, map, map2; 1111 u_int id, me; 1112 int iscpuset; 1113 1114 mtx_assert(&sched_lock, MA_OWNED); 1115 1116 CTR0(KTR_RUNQ, "forward_wakeup()"); 1117 1118 if ((!forward_wakeup_enabled) || 1119 (forward_wakeup_use_mask == 0 && forward_wakeup_use_loop == 0)) 1120 return (0); 1121 if (!smp_started || cold || panicstr) 1122 return (0); 1123 1124 forward_wakeups_requested++; 1125 1126 /* 1127 * Check the idle mask we received against what we calculated 1128 * before in the old version. 1129 */ 1130 me = PCPU_GET(cpuid); 1131 1132 /* Don't bother if we should be doing it ourself. */ 1133 if (CPU_ISSET(me, &idle_cpus_mask) && 1134 (cpunum == NOCPU || me == cpunum)) 1135 return (0); 1136 1137 CPU_SETOF(me, &dontuse); 1138 CPU_OR(&dontuse, &stopped_cpus); 1139 CPU_OR(&dontuse, &hlt_cpus_mask); 1140 CPU_ZERO(&map2); 1141 if (forward_wakeup_use_loop) { 1142 STAILQ_FOREACH(pc, &cpuhead, pc_allcpu) { 1143 id = pc->pc_cpuid; 1144 if (!CPU_ISSET(id, &dontuse) && 1145 pc->pc_curthread == pc->pc_idlethread) { 1146 CPU_SET(id, &map2); 1147 } 1148 } 1149 } 1150 1151 if (forward_wakeup_use_mask) { 1152 map = idle_cpus_mask; 1153 CPU_NAND(&map, &dontuse); 1154 1155 /* If they are both on, compare and use loop if different. */ 1156 if (forward_wakeup_use_loop) { 1157 if (CPU_CMP(&map, &map2)) { 1158 printf("map != map2, loop method preferred\n"); 1159 map = map2; 1160 } 1161 } 1162 } else { 1163 map = map2; 1164 } 1165 1166 /* If we only allow a specific CPU, then mask off all the others. */ 1167 if (cpunum != NOCPU) { 1168 KASSERT((cpunum <= mp_maxcpus),("forward_wakeup: bad cpunum.")); 1169 iscpuset = CPU_ISSET(cpunum, &map); 1170 if (iscpuset == 0) 1171 CPU_ZERO(&map); 1172 else 1173 CPU_SETOF(cpunum, &map); 1174 } 1175 if (!CPU_EMPTY(&map)) { 1176 forward_wakeups_delivered++; 1177 STAILQ_FOREACH(pc, &cpuhead, pc_allcpu) { 1178 id = pc->pc_cpuid; 1179 if (!CPU_ISSET(id, &map)) 1180 continue; 1181 if (cpu_idle_wakeup(pc->pc_cpuid)) 1182 CPU_CLR(id, &map); 1183 } 1184 if (!CPU_EMPTY(&map)) 1185 ipi_selected(map, IPI_AST); 1186 return (1); 1187 } 1188 if (cpunum == NOCPU) 1189 printf("forward_wakeup: Idle processor not found\n"); 1190 return (0); 1191 } 1192 1193 static void 1194 kick_other_cpu(int pri, int cpuid) 1195 { 1196 struct pcpu *pcpu; 1197 int cpri; 1198 1199 pcpu = pcpu_find(cpuid); 1200 if (CPU_ISSET(cpuid, &idle_cpus_mask)) { 1201 forward_wakeups_delivered++; 1202 if (!cpu_idle_wakeup(cpuid)) 1203 ipi_cpu(cpuid, IPI_AST); 1204 return; 1205 } 1206 1207 cpri = pcpu->pc_curthread->td_priority; 1208 if (pri >= cpri) 1209 return; 1210 1211 #if defined(IPI_PREEMPTION) && defined(PREEMPTION) 1212 #if !defined(FULL_PREEMPTION) 1213 if (pri <= PRI_MAX_ITHD) 1214 #endif /* ! FULL_PREEMPTION */ 1215 { 1216 ipi_cpu(cpuid, IPI_PREEMPT); 1217 return; 1218 } 1219 #endif /* defined(IPI_PREEMPTION) && defined(PREEMPTION) */ 1220 1221 pcpu->pc_curthread->td_flags |= TDF_NEEDRESCHED; 1222 ipi_cpu(cpuid, IPI_AST); 1223 return; 1224 } 1225 #endif /* SMP */ 1226 1227 #ifdef SMP 1228 static int 1229 sched_pickcpu(struct thread *td) 1230 { 1231 int best, cpu; 1232 1233 mtx_assert(&sched_lock, MA_OWNED); 1234 1235 if (THREAD_CAN_SCHED(td, td->td_lastcpu)) 1236 best = td->td_lastcpu; 1237 else 1238 best = NOCPU; 1239 CPU_FOREACH(cpu) { 1240 if (!THREAD_CAN_SCHED(td, cpu)) 1241 continue; 1242 1243 if (best == NOCPU) 1244 best = cpu; 1245 else if (runq_length[cpu] < runq_length[best]) 1246 best = cpu; 1247 } 1248 KASSERT(best != NOCPU, ("no valid CPUs")); 1249 1250 return (best); 1251 } 1252 #endif 1253 1254 void 1255 sched_add(struct thread *td, int flags) 1256 #ifdef SMP 1257 { 1258 cpuset_t tidlemsk; 1259 struct td_sched *ts; 1260 u_int cpu, cpuid; 1261 int forwarded = 0; 1262 int single_cpu = 0; 1263 1264 ts = td->td_sched; 1265 THREAD_LOCK_ASSERT(td, MA_OWNED); 1266 KASSERT((td->td_inhibitors == 0), 1267 ("sched_add: trying to run inhibited thread")); 1268 KASSERT((TD_CAN_RUN(td) || TD_IS_RUNNING(td)), 1269 ("sched_add: bad thread state")); 1270 KASSERT(td->td_flags & TDF_INMEM, 1271 ("sched_add: thread swapped out")); 1272 1273 KTR_STATE2(KTR_SCHED, "thread", sched_tdname(td), "runq add", 1274 "prio:%d", td->td_priority, KTR_ATTR_LINKED, 1275 sched_tdname(curthread)); 1276 KTR_POINT1(KTR_SCHED, "thread", sched_tdname(curthread), "wokeup", 1277 KTR_ATTR_LINKED, sched_tdname(td)); 1278 SDT_PROBE4(sched, , , enqueue, td, td->td_proc, NULL, 1279 flags & SRQ_PREEMPTED); 1280 1281 1282 /* 1283 * Now that the thread is moving to the run-queue, set the lock 1284 * to the scheduler's lock. 1285 */ 1286 if (td->td_lock != &sched_lock) { 1287 mtx_lock_spin(&sched_lock); 1288 thread_lock_set(td, &sched_lock); 1289 } 1290 TD_SET_RUNQ(td); 1291 1292 /* 1293 * If SMP is started and the thread is pinned or otherwise limited to 1294 * a specific set of CPUs, queue the thread to a per-CPU run queue. 1295 * Otherwise, queue the thread to the global run queue. 1296 * 1297 * If SMP has not yet been started we must use the global run queue 1298 * as per-CPU state may not be initialized yet and we may crash if we 1299 * try to access the per-CPU run queues. 1300 */ 1301 if (smp_started && (td->td_pinned != 0 || td->td_flags & TDF_BOUND || 1302 ts->ts_flags & TSF_AFFINITY)) { 1303 if (td->td_pinned != 0) 1304 cpu = td->td_lastcpu; 1305 else if (td->td_flags & TDF_BOUND) { 1306 /* Find CPU from bound runq. */ 1307 KASSERT(SKE_RUNQ_PCPU(ts), 1308 ("sched_add: bound td_sched not on cpu runq")); 1309 cpu = ts->ts_runq - &runq_pcpu[0]; 1310 } else 1311 /* Find a valid CPU for our cpuset */ 1312 cpu = sched_pickcpu(td); 1313 ts->ts_runq = &runq_pcpu[cpu]; 1314 single_cpu = 1; 1315 CTR3(KTR_RUNQ, 1316 "sched_add: Put td_sched:%p(td:%p) on cpu%d runq", ts, td, 1317 cpu); 1318 } else { 1319 CTR2(KTR_RUNQ, 1320 "sched_add: adding td_sched:%p (td:%p) to gbl runq", ts, 1321 td); 1322 cpu = NOCPU; 1323 ts->ts_runq = &runq; 1324 } 1325 1326 cpuid = PCPU_GET(cpuid); 1327 if (single_cpu && cpu != cpuid) { 1328 kick_other_cpu(td->td_priority, cpu); 1329 } else { 1330 if (!single_cpu) { 1331 tidlemsk = idle_cpus_mask; 1332 CPU_NAND(&tidlemsk, &hlt_cpus_mask); 1333 CPU_CLR(cpuid, &tidlemsk); 1334 1335 if (!CPU_ISSET(cpuid, &idle_cpus_mask) && 1336 ((flags & SRQ_INTR) == 0) && 1337 !CPU_EMPTY(&tidlemsk)) 1338 forwarded = forward_wakeup(cpu); 1339 } 1340 1341 if (!forwarded) { 1342 if ((flags & SRQ_YIELDING) == 0 && maybe_preempt(td)) 1343 return; 1344 else 1345 maybe_resched(td); 1346 } 1347 } 1348 1349 if ((td->td_flags & TDF_NOLOAD) == 0) 1350 sched_load_add(); 1351 runq_add(ts->ts_runq, td, flags); 1352 if (cpu != NOCPU) 1353 runq_length[cpu]++; 1354 } 1355 #else /* SMP */ 1356 { 1357 struct td_sched *ts; 1358 1359 ts = td->td_sched; 1360 THREAD_LOCK_ASSERT(td, MA_OWNED); 1361 KASSERT((td->td_inhibitors == 0), 1362 ("sched_add: trying to run inhibited thread")); 1363 KASSERT((TD_CAN_RUN(td) || TD_IS_RUNNING(td)), 1364 ("sched_add: bad thread state")); 1365 KASSERT(td->td_flags & TDF_INMEM, 1366 ("sched_add: thread swapped out")); 1367 KTR_STATE2(KTR_SCHED, "thread", sched_tdname(td), "runq add", 1368 "prio:%d", td->td_priority, KTR_ATTR_LINKED, 1369 sched_tdname(curthread)); 1370 KTR_POINT1(KTR_SCHED, "thread", sched_tdname(curthread), "wokeup", 1371 KTR_ATTR_LINKED, sched_tdname(td)); 1372 SDT_PROBE4(sched, , , enqueue, td, td->td_proc, NULL, 1373 flags & SRQ_PREEMPTED); 1374 1375 /* 1376 * Now that the thread is moving to the run-queue, set the lock 1377 * to the scheduler's lock. 1378 */ 1379 if (td->td_lock != &sched_lock) { 1380 mtx_lock_spin(&sched_lock); 1381 thread_lock_set(td, &sched_lock); 1382 } 1383 TD_SET_RUNQ(td); 1384 CTR2(KTR_RUNQ, "sched_add: adding td_sched:%p (td:%p) to runq", ts, td); 1385 ts->ts_runq = &runq; 1386 1387 /* 1388 * If we are yielding (on the way out anyhow) or the thread 1389 * being saved is US, then don't try be smart about preemption 1390 * or kicking off another CPU as it won't help and may hinder. 1391 * In the YIEDLING case, we are about to run whoever is being 1392 * put in the queue anyhow, and in the OURSELF case, we are 1393 * puting ourself on the run queue which also only happens 1394 * when we are about to yield. 1395 */ 1396 if ((flags & SRQ_YIELDING) == 0) { 1397 if (maybe_preempt(td)) 1398 return; 1399 } 1400 if ((td->td_flags & TDF_NOLOAD) == 0) 1401 sched_load_add(); 1402 runq_add(ts->ts_runq, td, flags); 1403 maybe_resched(td); 1404 } 1405 #endif /* SMP */ 1406 1407 void 1408 sched_rem(struct thread *td) 1409 { 1410 struct td_sched *ts; 1411 1412 ts = td->td_sched; 1413 KASSERT(td->td_flags & TDF_INMEM, 1414 ("sched_rem: thread swapped out")); 1415 KASSERT(TD_ON_RUNQ(td), 1416 ("sched_rem: thread not on run queue")); 1417 mtx_assert(&sched_lock, MA_OWNED); 1418 KTR_STATE2(KTR_SCHED, "thread", sched_tdname(td), "runq rem", 1419 "prio:%d", td->td_priority, KTR_ATTR_LINKED, 1420 sched_tdname(curthread)); 1421 SDT_PROBE3(sched, , , dequeue, td, td->td_proc, NULL); 1422 1423 if ((td->td_flags & TDF_NOLOAD) == 0) 1424 sched_load_rem(); 1425 #ifdef SMP 1426 if (ts->ts_runq != &runq) 1427 runq_length[ts->ts_runq - runq_pcpu]--; 1428 #endif 1429 runq_remove(ts->ts_runq, td); 1430 TD_SET_CAN_RUN(td); 1431 } 1432 1433 /* 1434 * Select threads to run. Note that running threads still consume a 1435 * slot. 1436 */ 1437 struct thread * 1438 sched_choose(void) 1439 { 1440 struct thread *td; 1441 struct runq *rq; 1442 1443 mtx_assert(&sched_lock, MA_OWNED); 1444 #ifdef SMP 1445 struct thread *tdcpu; 1446 1447 rq = &runq; 1448 td = runq_choose_fuzz(&runq, runq_fuzz); 1449 tdcpu = runq_choose(&runq_pcpu[PCPU_GET(cpuid)]); 1450 1451 if (td == NULL || 1452 (tdcpu != NULL && 1453 tdcpu->td_priority < td->td_priority)) { 1454 CTR2(KTR_RUNQ, "choosing td %p from pcpu runq %d", tdcpu, 1455 PCPU_GET(cpuid)); 1456 td = tdcpu; 1457 rq = &runq_pcpu[PCPU_GET(cpuid)]; 1458 } else { 1459 CTR1(KTR_RUNQ, "choosing td_sched %p from main runq", td); 1460 } 1461 1462 #else 1463 rq = &runq; 1464 td = runq_choose(&runq); 1465 #endif 1466 1467 if (td) { 1468 #ifdef SMP 1469 if (td == tdcpu) 1470 runq_length[PCPU_GET(cpuid)]--; 1471 #endif 1472 runq_remove(rq, td); 1473 td->td_flags |= TDF_DIDRUN; 1474 1475 KASSERT(td->td_flags & TDF_INMEM, 1476 ("sched_choose: thread swapped out")); 1477 return (td); 1478 } 1479 return (PCPU_GET(idlethread)); 1480 } 1481 1482 void 1483 sched_preempt(struct thread *td) 1484 { 1485 1486 SDT_PROBE2(sched, , , surrender, td, td->td_proc); 1487 thread_lock(td); 1488 if (td->td_critnest > 1) 1489 td->td_owepreempt = 1; 1490 else 1491 mi_switch(SW_INVOL | SW_PREEMPT | SWT_PREEMPT, NULL); 1492 thread_unlock(td); 1493 } 1494 1495 void 1496 sched_userret(struct thread *td) 1497 { 1498 /* 1499 * XXX we cheat slightly on the locking here to avoid locking in 1500 * the usual case. Setting td_priority here is essentially an 1501 * incomplete workaround for not setting it properly elsewhere. 1502 * Now that some interrupt handlers are threads, not setting it 1503 * properly elsewhere can clobber it in the window between setting 1504 * it here and returning to user mode, so don't waste time setting 1505 * it perfectly here. 1506 */ 1507 KASSERT((td->td_flags & TDF_BORROWING) == 0, 1508 ("thread with borrowed priority returning to userland")); 1509 if (td->td_priority != td->td_user_pri) { 1510 thread_lock(td); 1511 td->td_priority = td->td_user_pri; 1512 td->td_base_pri = td->td_user_pri; 1513 thread_unlock(td); 1514 } 1515 } 1516 1517 void 1518 sched_bind(struct thread *td, int cpu) 1519 { 1520 struct td_sched *ts; 1521 1522 THREAD_LOCK_ASSERT(td, MA_OWNED|MA_NOTRECURSED); 1523 KASSERT(td == curthread, ("sched_bind: can only bind curthread")); 1524 1525 ts = td->td_sched; 1526 1527 td->td_flags |= TDF_BOUND; 1528 #ifdef SMP 1529 ts->ts_runq = &runq_pcpu[cpu]; 1530 if (PCPU_GET(cpuid) == cpu) 1531 return; 1532 1533 mi_switch(SW_VOL, NULL); 1534 #endif 1535 } 1536 1537 void 1538 sched_unbind(struct thread* td) 1539 { 1540 THREAD_LOCK_ASSERT(td, MA_OWNED); 1541 KASSERT(td == curthread, ("sched_unbind: can only bind curthread")); 1542 td->td_flags &= ~TDF_BOUND; 1543 } 1544 1545 int 1546 sched_is_bound(struct thread *td) 1547 { 1548 THREAD_LOCK_ASSERT(td, MA_OWNED); 1549 return (td->td_flags & TDF_BOUND); 1550 } 1551 1552 void 1553 sched_relinquish(struct thread *td) 1554 { 1555 thread_lock(td); 1556 mi_switch(SW_VOL | SWT_RELINQUISH, NULL); 1557 thread_unlock(td); 1558 } 1559 1560 int 1561 sched_load(void) 1562 { 1563 return (sched_tdcnt); 1564 } 1565 1566 int 1567 sched_sizeof_proc(void) 1568 { 1569 return (sizeof(struct proc)); 1570 } 1571 1572 int 1573 sched_sizeof_thread(void) 1574 { 1575 return (sizeof(struct thread) + sizeof(struct td_sched)); 1576 } 1577 1578 fixpt_t 1579 sched_pctcpu(struct thread *td) 1580 { 1581 struct td_sched *ts; 1582 1583 THREAD_LOCK_ASSERT(td, MA_OWNED); 1584 ts = td->td_sched; 1585 return (ts->ts_pctcpu); 1586 } 1587 1588 #ifdef RACCT 1589 /* 1590 * Calculates the contribution to the thread cpu usage for the latest 1591 * (unfinished) second. 1592 */ 1593 fixpt_t 1594 sched_pctcpu_delta(struct thread *td) 1595 { 1596 struct td_sched *ts; 1597 fixpt_t delta; 1598 int realstathz; 1599 1600 THREAD_LOCK_ASSERT(td, MA_OWNED); 1601 ts = td->td_sched; 1602 delta = 0; 1603 realstathz = stathz ? stathz : hz; 1604 if (ts->ts_cpticks != 0) { 1605 #if (FSHIFT >= CCPU_SHIFT) 1606 delta = (realstathz == 100) 1607 ? ((fixpt_t) ts->ts_cpticks) << 1608 (FSHIFT - CCPU_SHIFT) : 1609 100 * (((fixpt_t) ts->ts_cpticks) 1610 << (FSHIFT - CCPU_SHIFT)) / realstathz; 1611 #else 1612 delta = ((FSCALE - ccpu) * 1613 (ts->ts_cpticks * 1614 FSCALE / realstathz)) >> FSHIFT; 1615 #endif 1616 } 1617 1618 return (delta); 1619 } 1620 #endif 1621 1622 void 1623 sched_tick(int cnt) 1624 { 1625 } 1626 1627 /* 1628 * The actual idle process. 1629 */ 1630 void 1631 sched_idletd(void *dummy) 1632 { 1633 struct pcpuidlestat *stat; 1634 1635 THREAD_NO_SLEEPING(); 1636 stat = DPCPU_PTR(idlestat); 1637 for (;;) { 1638 mtx_assert(&Giant, MA_NOTOWNED); 1639 1640 while (sched_runnable() == 0) { 1641 cpu_idle(stat->idlecalls + stat->oldidlecalls > 64); 1642 stat->idlecalls++; 1643 } 1644 1645 mtx_lock_spin(&sched_lock); 1646 mi_switch(SW_VOL | SWT_IDLE, NULL); 1647 mtx_unlock_spin(&sched_lock); 1648 } 1649 } 1650 1651 /* 1652 * A CPU is entering for the first time or a thread is exiting. 1653 */ 1654 void 1655 sched_throw(struct thread *td) 1656 { 1657 /* 1658 * Correct spinlock nesting. The idle thread context that we are 1659 * borrowing was created so that it would start out with a single 1660 * spin lock (sched_lock) held in fork_trampoline(). Since we've 1661 * explicitly acquired locks in this function, the nesting count 1662 * is now 2 rather than 1. Since we are nested, calling 1663 * spinlock_exit() will simply adjust the counts without allowing 1664 * spin lock using code to interrupt us. 1665 */ 1666 if (td == NULL) { 1667 mtx_lock_spin(&sched_lock); 1668 spinlock_exit(); 1669 PCPU_SET(switchtime, cpu_ticks()); 1670 PCPU_SET(switchticks, ticks); 1671 } else { 1672 lock_profile_release_lock(&sched_lock.lock_object); 1673 MPASS(td->td_lock == &sched_lock); 1674 } 1675 mtx_assert(&sched_lock, MA_OWNED); 1676 KASSERT(curthread->td_md.md_spinlock_count == 1, ("invalid count")); 1677 cpu_throw(td, choosethread()); /* doesn't return */ 1678 } 1679 1680 void 1681 sched_fork_exit(struct thread *td) 1682 { 1683 1684 /* 1685 * Finish setting up thread glue so that it begins execution in a 1686 * non-nested critical section with sched_lock held but not recursed. 1687 */ 1688 td->td_oncpu = PCPU_GET(cpuid); 1689 sched_lock.mtx_lock = (uintptr_t)td; 1690 lock_profile_obtain_lock_success(&sched_lock.lock_object, 1691 0, 0, __FILE__, __LINE__); 1692 THREAD_LOCK_ASSERT(td, MA_OWNED | MA_NOTRECURSED); 1693 } 1694 1695 char * 1696 sched_tdname(struct thread *td) 1697 { 1698 #ifdef KTR 1699 struct td_sched *ts; 1700 1701 ts = td->td_sched; 1702 if (ts->ts_name[0] == '\0') 1703 snprintf(ts->ts_name, sizeof(ts->ts_name), 1704 "%s tid %d", td->td_name, td->td_tid); 1705 return (ts->ts_name); 1706 #else 1707 return (td->td_name); 1708 #endif 1709 } 1710 1711 #ifdef KTR 1712 void 1713 sched_clear_tdname(struct thread *td) 1714 { 1715 struct td_sched *ts; 1716 1717 ts = td->td_sched; 1718 ts->ts_name[0] = '\0'; 1719 } 1720 #endif 1721 1722 void 1723 sched_affinity(struct thread *td) 1724 { 1725 #ifdef SMP 1726 struct td_sched *ts; 1727 int cpu; 1728 1729 THREAD_LOCK_ASSERT(td, MA_OWNED); 1730 1731 /* 1732 * Set the TSF_AFFINITY flag if there is at least one CPU this 1733 * thread can't run on. 1734 */ 1735 ts = td->td_sched; 1736 ts->ts_flags &= ~TSF_AFFINITY; 1737 CPU_FOREACH(cpu) { 1738 if (!THREAD_CAN_SCHED(td, cpu)) { 1739 ts->ts_flags |= TSF_AFFINITY; 1740 break; 1741 } 1742 } 1743 1744 /* 1745 * If this thread can run on all CPUs, nothing else to do. 1746 */ 1747 if (!(ts->ts_flags & TSF_AFFINITY)) 1748 return; 1749 1750 /* Pinned threads and bound threads should be left alone. */ 1751 if (td->td_pinned != 0 || td->td_flags & TDF_BOUND) 1752 return; 1753 1754 switch (td->td_state) { 1755 case TDS_RUNQ: 1756 /* 1757 * If we are on a per-CPU runqueue that is in the set, 1758 * then nothing needs to be done. 1759 */ 1760 if (ts->ts_runq != &runq && 1761 THREAD_CAN_SCHED(td, ts->ts_runq - runq_pcpu)) 1762 return; 1763 1764 /* Put this thread on a valid per-CPU runqueue. */ 1765 sched_rem(td); 1766 sched_add(td, SRQ_BORING); 1767 break; 1768 case TDS_RUNNING: 1769 /* 1770 * See if our current CPU is in the set. If not, force a 1771 * context switch. 1772 */ 1773 if (THREAD_CAN_SCHED(td, td->td_oncpu)) 1774 return; 1775 1776 td->td_flags |= TDF_NEEDRESCHED; 1777 if (td != curthread) 1778 ipi_cpu(cpu, IPI_AST); 1779 break; 1780 default: 1781 break; 1782 } 1783 #endif 1784 } 1785