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/smp.h> 54 #include <sys/sysctl.h> 55 #include <sys/sx.h> 56 #include <sys/turnstile.h> 57 #include <sys/umtx.h> 58 #include <machine/pcb.h> 59 #include <machine/smp.h> 60 61 #ifdef HWPMC_HOOKS 62 #include <sys/pmckern.h> 63 #endif 64 65 #ifdef KDTRACE_HOOKS 66 #include <sys/dtrace_bsd.h> 67 int dtrace_vtime_active; 68 dtrace_vtime_switch_func_t dtrace_vtime_switch_func; 69 #endif 70 71 /* 72 * INVERSE_ESTCPU_WEIGHT is only suitable for statclock() frequencies in 73 * the range 100-256 Hz (approximately). 74 */ 75 #define ESTCPULIM(e) \ 76 min((e), INVERSE_ESTCPU_WEIGHT * (NICE_WEIGHT * (PRIO_MAX - PRIO_MIN) - \ 77 RQ_PPQ) + INVERSE_ESTCPU_WEIGHT - 1) 78 #ifdef SMP 79 #define INVERSE_ESTCPU_WEIGHT (8 * smp_cpus) 80 #else 81 #define INVERSE_ESTCPU_WEIGHT 8 /* 1 / (priorities per estcpu level). */ 82 #endif 83 #define NICE_WEIGHT 1 /* Priorities per nice level. */ 84 85 #define TS_NAME_LEN (MAXCOMLEN + sizeof(" td ") + sizeof(__XSTRING(UINT_MAX))) 86 87 /* 88 * The schedulable entity that runs a context. 89 * This is an extension to the thread structure and is tailored to 90 * the requirements of this scheduler 91 */ 92 struct td_sched { 93 fixpt_t ts_pctcpu; /* (j) %cpu during p_swtime. */ 94 int ts_cpticks; /* (j) Ticks of cpu time. */ 95 int ts_slptime; /* (j) Seconds !RUNNING. */ 96 int ts_flags; 97 struct runq *ts_runq; /* runq the thread is currently on */ 98 #ifdef KTR 99 char ts_name[TS_NAME_LEN]; 100 #endif 101 }; 102 103 /* flags kept in td_flags */ 104 #define TDF_DIDRUN TDF_SCHED0 /* thread actually ran. */ 105 #define TDF_BOUND TDF_SCHED1 /* Bound to one CPU. */ 106 107 /* flags kept in ts_flags */ 108 #define TSF_AFFINITY 0x0001 /* Has a non-"full" CPU set. */ 109 110 #define SKE_RUNQ_PCPU(ts) \ 111 ((ts)->ts_runq != 0 && (ts)->ts_runq != &runq) 112 113 #define THREAD_CAN_SCHED(td, cpu) \ 114 CPU_ISSET((cpu), &(td)->td_cpuset->cs_mask) 115 116 static struct td_sched td_sched0; 117 struct mtx sched_lock; 118 119 static int sched_tdcnt; /* Total runnable threads in the system. */ 120 static int sched_quantum; /* Roundrobin scheduling quantum in ticks. */ 121 #define SCHED_QUANTUM (hz / 10) /* Default sched quantum */ 122 123 static void setup_runqs(void); 124 static void schedcpu(void); 125 static void schedcpu_thread(void); 126 static void sched_priority(struct thread *td, u_char prio); 127 static void sched_setup(void *dummy); 128 static void maybe_resched(struct thread *td); 129 static void updatepri(struct thread *td); 130 static void resetpriority(struct thread *td); 131 static void resetpriority_thread(struct thread *td); 132 #ifdef SMP 133 static int sched_pickcpu(struct thread *td); 134 static int forward_wakeup(int cpunum); 135 static void kick_other_cpu(int pri, int cpuid); 136 #endif 137 138 static struct kproc_desc sched_kp = { 139 "schedcpu", 140 schedcpu_thread, 141 NULL 142 }; 143 SYSINIT(schedcpu, SI_SUB_RUN_SCHEDULER, SI_ORDER_FIRST, kproc_start, 144 &sched_kp); 145 SYSINIT(sched_setup, SI_SUB_RUN_QUEUE, SI_ORDER_FIRST, sched_setup, NULL); 146 147 /* 148 * Global run queue. 149 */ 150 static struct runq runq; 151 152 #ifdef SMP 153 /* 154 * Per-CPU run queues 155 */ 156 static struct runq runq_pcpu[MAXCPU]; 157 long runq_length[MAXCPU]; 158 #endif 159 160 struct pcpuidlestat { 161 u_int idlecalls; 162 u_int oldidlecalls; 163 }; 164 static DPCPU_DEFINE(struct pcpuidlestat, idlestat); 165 166 static void 167 setup_runqs(void) 168 { 169 #ifdef SMP 170 int i; 171 172 for (i = 0; i < MAXCPU; ++i) 173 runq_init(&runq_pcpu[i]); 174 #endif 175 176 runq_init(&runq); 177 } 178 179 static int 180 sysctl_kern_quantum(SYSCTL_HANDLER_ARGS) 181 { 182 int error, new_val; 183 184 new_val = sched_quantum * tick; 185 error = sysctl_handle_int(oidp, &new_val, 0, req); 186 if (error != 0 || req->newptr == NULL) 187 return (error); 188 if (new_val < tick) 189 return (EINVAL); 190 sched_quantum = new_val / tick; 191 hogticks = 2 * sched_quantum; 192 return (0); 193 } 194 195 SYSCTL_NODE(_kern, OID_AUTO, sched, CTLFLAG_RD, 0, "Scheduler"); 196 197 SYSCTL_STRING(_kern_sched, OID_AUTO, name, CTLFLAG_RD, "4BSD", 0, 198 "Scheduler name"); 199 200 SYSCTL_PROC(_kern_sched, OID_AUTO, quantum, CTLTYPE_INT | CTLFLAG_RW, 201 0, sizeof sched_quantum, sysctl_kern_quantum, "I", 202 "Roundrobin scheduling quantum in microseconds"); 203 204 #ifdef SMP 205 /* Enable forwarding of wakeups to all other cpus */ 206 SYSCTL_NODE(_kern_sched, OID_AUTO, ipiwakeup, CTLFLAG_RD, NULL, "Kernel SMP"); 207 208 static int runq_fuzz = 1; 209 SYSCTL_INT(_kern_sched, OID_AUTO, runq_fuzz, CTLFLAG_RW, &runq_fuzz, 0, ""); 210 211 static int forward_wakeup_enabled = 1; 212 SYSCTL_INT(_kern_sched_ipiwakeup, OID_AUTO, enabled, CTLFLAG_RW, 213 &forward_wakeup_enabled, 0, 214 "Forwarding of wakeup to idle CPUs"); 215 216 static int forward_wakeups_requested = 0; 217 SYSCTL_INT(_kern_sched_ipiwakeup, OID_AUTO, requested, CTLFLAG_RD, 218 &forward_wakeups_requested, 0, 219 "Requests for Forwarding of wakeup to idle CPUs"); 220 221 static int forward_wakeups_delivered = 0; 222 SYSCTL_INT(_kern_sched_ipiwakeup, OID_AUTO, delivered, CTLFLAG_RD, 223 &forward_wakeups_delivered, 0, 224 "Completed Forwarding of wakeup to idle CPUs"); 225 226 static int forward_wakeup_use_mask = 1; 227 SYSCTL_INT(_kern_sched_ipiwakeup, OID_AUTO, usemask, CTLFLAG_RW, 228 &forward_wakeup_use_mask, 0, 229 "Use the mask of idle cpus"); 230 231 static int forward_wakeup_use_loop = 0; 232 SYSCTL_INT(_kern_sched_ipiwakeup, OID_AUTO, useloop, CTLFLAG_RW, 233 &forward_wakeup_use_loop, 0, 234 "Use a loop to find idle cpus"); 235 236 static int forward_wakeup_use_single = 0; 237 SYSCTL_INT(_kern_sched_ipiwakeup, OID_AUTO, onecpu, CTLFLAG_RW, 238 &forward_wakeup_use_single, 0, 239 "Only signal one idle cpu"); 240 241 static int forward_wakeup_use_htt = 0; 242 SYSCTL_INT(_kern_sched_ipiwakeup, OID_AUTO, htt2, CTLFLAG_RW, 243 &forward_wakeup_use_htt, 0, 244 "account for htt"); 245 246 #endif 247 #if 0 248 static int sched_followon = 0; 249 SYSCTL_INT(_kern_sched, OID_AUTO, followon, CTLFLAG_RW, 250 &sched_followon, 0, 251 "allow threads to share a quantum"); 252 #endif 253 254 static __inline void 255 sched_load_add(void) 256 { 257 258 sched_tdcnt++; 259 KTR_COUNTER0(KTR_SCHED, "load", "global load", sched_tdcnt); 260 } 261 262 static __inline void 263 sched_load_rem(void) 264 { 265 266 sched_tdcnt--; 267 KTR_COUNTER0(KTR_SCHED, "load", "global load", sched_tdcnt); 268 } 269 /* 270 * Arrange to reschedule if necessary, taking the priorities and 271 * schedulers into account. 272 */ 273 static void 274 maybe_resched(struct thread *td) 275 { 276 277 THREAD_LOCK_ASSERT(td, MA_OWNED); 278 if (td->td_priority < curthread->td_priority) 279 curthread->td_flags |= TDF_NEEDRESCHED; 280 } 281 282 /* 283 * This function is called when a thread is about to be put on run queue 284 * because it has been made runnable or its priority has been adjusted. It 285 * determines if the new thread should be immediately preempted to. If so, 286 * it switches to it and eventually returns true. If not, it returns false 287 * so that the caller may place the thread on an appropriate run queue. 288 */ 289 int 290 maybe_preempt(struct thread *td) 291 { 292 #ifdef PREEMPTION 293 struct thread *ctd; 294 int cpri, pri; 295 296 /* 297 * The new thread should not preempt the current thread if any of the 298 * following conditions are true: 299 * 300 * - The kernel is in the throes of crashing (panicstr). 301 * - The current thread has a higher (numerically lower) or 302 * equivalent priority. Note that this prevents curthread from 303 * trying to preempt to itself. 304 * - It is too early in the boot for context switches (cold is set). 305 * - The current thread has an inhibitor set or is in the process of 306 * exiting. In this case, the current thread is about to switch 307 * out anyways, so there's no point in preempting. If we did, 308 * the current thread would not be properly resumed as well, so 309 * just avoid that whole landmine. 310 * - If the new thread's priority is not a realtime priority and 311 * the current thread's priority is not an idle priority and 312 * FULL_PREEMPTION is disabled. 313 * 314 * If all of these conditions are false, but the current thread is in 315 * a nested critical section, then we have to defer the preemption 316 * until we exit the critical section. Otherwise, switch immediately 317 * to the new thread. 318 */ 319 ctd = curthread; 320 THREAD_LOCK_ASSERT(td, MA_OWNED); 321 KASSERT((td->td_inhibitors == 0), 322 ("maybe_preempt: trying to run inhibited thread")); 323 pri = td->td_priority; 324 cpri = ctd->td_priority; 325 if (panicstr != NULL || pri >= cpri || cold /* || dumping */ || 326 TD_IS_INHIBITED(ctd)) 327 return (0); 328 #ifndef FULL_PREEMPTION 329 if (pri > PRI_MAX_ITHD && cpri < PRI_MIN_IDLE) 330 return (0); 331 #endif 332 333 if (ctd->td_critnest > 1) { 334 CTR1(KTR_PROC, "maybe_preempt: in critical section %d", 335 ctd->td_critnest); 336 ctd->td_owepreempt = 1; 337 return (0); 338 } 339 /* 340 * Thread is runnable but not yet put on system run queue. 341 */ 342 MPASS(ctd->td_lock == td->td_lock); 343 MPASS(TD_ON_RUNQ(td)); 344 TD_SET_RUNNING(td); 345 CTR3(KTR_PROC, "preempting to thread %p (pid %d, %s)\n", td, 346 td->td_proc->p_pid, td->td_name); 347 mi_switch(SW_INVOL | SW_PREEMPT | SWT_PREEMPT, td); 348 /* 349 * td's lock pointer may have changed. We have to return with it 350 * locked. 351 */ 352 spinlock_enter(); 353 thread_unlock(ctd); 354 thread_lock(td); 355 spinlock_exit(); 356 return (1); 357 #else 358 return (0); 359 #endif 360 } 361 362 /* 363 * Constants for digital decay and forget: 364 * 90% of (td_estcpu) usage in 5 * loadav time 365 * 95% of (ts_pctcpu) usage in 60 seconds (load insensitive) 366 * Note that, as ps(1) mentions, this can let percentages 367 * total over 100% (I've seen 137.9% for 3 processes). 368 * 369 * Note that schedclock() updates td_estcpu and p_cpticks asynchronously. 370 * 371 * We wish to decay away 90% of td_estcpu in (5 * loadavg) seconds. 372 * That is, the system wants to compute a value of decay such 373 * that the following for loop: 374 * for (i = 0; i < (5 * loadavg); i++) 375 * td_estcpu *= decay; 376 * will compute 377 * td_estcpu *= 0.1; 378 * for all values of loadavg: 379 * 380 * Mathematically this loop can be expressed by saying: 381 * decay ** (5 * loadavg) ~= .1 382 * 383 * The system computes decay as: 384 * decay = (2 * loadavg) / (2 * loadavg + 1) 385 * 386 * We wish to prove that the system's computation of decay 387 * will always fulfill the equation: 388 * decay ** (5 * loadavg) ~= .1 389 * 390 * If we compute b as: 391 * b = 2 * loadavg 392 * then 393 * decay = b / (b + 1) 394 * 395 * We now need to prove two things: 396 * 1) Given factor ** (5 * loadavg) ~= .1, prove factor == b/(b+1) 397 * 2) Given b/(b+1) ** power ~= .1, prove power == (5 * loadavg) 398 * 399 * Facts: 400 * For x close to zero, exp(x) =~ 1 + x, since 401 * exp(x) = 0! + x**1/1! + x**2/2! + ... . 402 * therefore exp(-1/b) =~ 1 - (1/b) = (b-1)/b. 403 * For x close to zero, ln(1+x) =~ x, since 404 * ln(1+x) = x - x**2/2 + x**3/3 - ... -1 < x < 1 405 * therefore ln(b/(b+1)) = ln(1 - 1/(b+1)) =~ -1/(b+1). 406 * ln(.1) =~ -2.30 407 * 408 * Proof of (1): 409 * Solve (factor)**(power) =~ .1 given power (5*loadav): 410 * solving for factor, 411 * ln(factor) =~ (-2.30/5*loadav), or 412 * factor =~ exp(-1/((5/2.30)*loadav)) =~ exp(-1/(2*loadav)) = 413 * exp(-1/b) =~ (b-1)/b =~ b/(b+1). QED 414 * 415 * Proof of (2): 416 * Solve (factor)**(power) =~ .1 given factor == (b/(b+1)): 417 * solving for power, 418 * power*ln(b/(b+1)) =~ -2.30, or 419 * power =~ 2.3 * (b + 1) = 4.6*loadav + 2.3 =~ 5*loadav. QED 420 * 421 * Actual power values for the implemented algorithm are as follows: 422 * loadav: 1 2 3 4 423 * power: 5.68 10.32 14.94 19.55 424 */ 425 426 /* calculations for digital decay to forget 90% of usage in 5*loadav sec */ 427 #define loadfactor(loadav) (2 * (loadav)) 428 #define decay_cpu(loadfac, cpu) (((loadfac) * (cpu)) / ((loadfac) + FSCALE)) 429 430 /* decay 95% of `ts_pctcpu' in 60 seconds; see CCPU_SHIFT before changing */ 431 static fixpt_t ccpu = 0.95122942450071400909 * FSCALE; /* exp(-1/20) */ 432 SYSCTL_INT(_kern, OID_AUTO, ccpu, CTLFLAG_RD, &ccpu, 0, ""); 433 434 /* 435 * If `ccpu' is not equal to `exp(-1/20)' and you still want to use the 436 * faster/more-accurate formula, you'll have to estimate CCPU_SHIFT below 437 * and possibly adjust FSHIFT in "param.h" so that (FSHIFT >= CCPU_SHIFT). 438 * 439 * To estimate CCPU_SHIFT for exp(-1/20), the following formula was used: 440 * 1 - exp(-1/20) ~= 0.0487 ~= 0.0488 == 1 (fixed pt, *11* bits). 441 * 442 * If you don't want to bother with the faster/more-accurate formula, you 443 * can set CCPU_SHIFT to (FSHIFT + 1) which will use a slower/less-accurate 444 * (more general) method of calculating the %age of CPU used by a process. 445 */ 446 #define CCPU_SHIFT 11 447 448 /* 449 * Recompute process priorities, every hz ticks. 450 * MP-safe, called without the Giant mutex. 451 */ 452 /* ARGSUSED */ 453 static void 454 schedcpu(void) 455 { 456 register fixpt_t loadfac = loadfactor(averunnable.ldavg[0]); 457 struct thread *td; 458 struct proc *p; 459 struct td_sched *ts; 460 int awake, realstathz; 461 462 realstathz = stathz ? stathz : hz; 463 sx_slock(&allproc_lock); 464 FOREACH_PROC_IN_SYSTEM(p) { 465 PROC_LOCK(p); 466 FOREACH_THREAD_IN_PROC(p, td) { 467 awake = 0; 468 thread_lock(td); 469 ts = td->td_sched; 470 /* 471 * Increment sleep time (if sleeping). We 472 * ignore overflow, as above. 473 */ 474 /* 475 * The td_sched slptimes are not touched in wakeup 476 * because the thread may not HAVE everything in 477 * memory? XXX I think this is out of date. 478 */ 479 if (TD_ON_RUNQ(td)) { 480 awake = 1; 481 td->td_flags &= ~TDF_DIDRUN; 482 } else if (TD_IS_RUNNING(td)) { 483 awake = 1; 484 /* Do not clear TDF_DIDRUN */ 485 } else if (td->td_flags & TDF_DIDRUN) { 486 awake = 1; 487 td->td_flags &= ~TDF_DIDRUN; 488 } 489 490 /* 491 * ts_pctcpu is only for ps and ttyinfo(). 492 */ 493 ts->ts_pctcpu = (ts->ts_pctcpu * ccpu) >> FSHIFT; 494 /* 495 * If the td_sched has been idle the entire second, 496 * stop recalculating its priority until 497 * it wakes up. 498 */ 499 if (ts->ts_cpticks != 0) { 500 #if (FSHIFT >= CCPU_SHIFT) 501 ts->ts_pctcpu += (realstathz == 100) 502 ? ((fixpt_t) ts->ts_cpticks) << 503 (FSHIFT - CCPU_SHIFT) : 504 100 * (((fixpt_t) ts->ts_cpticks) 505 << (FSHIFT - CCPU_SHIFT)) / realstathz; 506 #else 507 ts->ts_pctcpu += ((FSCALE - ccpu) * 508 (ts->ts_cpticks * 509 FSCALE / realstathz)) >> FSHIFT; 510 #endif 511 ts->ts_cpticks = 0; 512 } 513 /* 514 * If there are ANY running threads in this process, 515 * then don't count it as sleeping. 516 * XXX: this is broken. 517 */ 518 if (awake) { 519 if (ts->ts_slptime > 1) { 520 /* 521 * In an ideal world, this should not 522 * happen, because whoever woke us 523 * up from the long sleep should have 524 * unwound the slptime and reset our 525 * priority before we run at the stale 526 * priority. Should KASSERT at some 527 * point when all the cases are fixed. 528 */ 529 updatepri(td); 530 } 531 ts->ts_slptime = 0; 532 } else 533 ts->ts_slptime++; 534 if (ts->ts_slptime > 1) { 535 thread_unlock(td); 536 continue; 537 } 538 td->td_estcpu = decay_cpu(loadfac, td->td_estcpu); 539 resetpriority(td); 540 resetpriority_thread(td); 541 thread_unlock(td); 542 } 543 PROC_UNLOCK(p); 544 } 545 sx_sunlock(&allproc_lock); 546 } 547 548 /* 549 * Main loop for a kthread that executes schedcpu once a second. 550 */ 551 static void 552 schedcpu_thread(void) 553 { 554 555 for (;;) { 556 schedcpu(); 557 pause("-", hz); 558 } 559 } 560 561 /* 562 * Recalculate the priority of a process after it has slept for a while. 563 * For all load averages >= 1 and max td_estcpu of 255, sleeping for at 564 * least six times the loadfactor will decay td_estcpu to zero. 565 */ 566 static void 567 updatepri(struct thread *td) 568 { 569 struct td_sched *ts; 570 fixpt_t loadfac; 571 unsigned int newcpu; 572 573 ts = td->td_sched; 574 loadfac = loadfactor(averunnable.ldavg[0]); 575 if (ts->ts_slptime > 5 * loadfac) 576 td->td_estcpu = 0; 577 else { 578 newcpu = td->td_estcpu; 579 ts->ts_slptime--; /* was incremented in schedcpu() */ 580 while (newcpu && --ts->ts_slptime) 581 newcpu = decay_cpu(loadfac, newcpu); 582 td->td_estcpu = newcpu; 583 } 584 } 585 586 /* 587 * Compute the priority of a process when running in user mode. 588 * Arrange to reschedule if the resulting priority is better 589 * than that of the current process. 590 */ 591 static void 592 resetpriority(struct thread *td) 593 { 594 register unsigned int newpriority; 595 596 if (td->td_pri_class == PRI_TIMESHARE) { 597 newpriority = PUSER + td->td_estcpu / INVERSE_ESTCPU_WEIGHT + 598 NICE_WEIGHT * (td->td_proc->p_nice - PRIO_MIN); 599 newpriority = min(max(newpriority, PRI_MIN_TIMESHARE), 600 PRI_MAX_TIMESHARE); 601 sched_user_prio(td, newpriority); 602 } 603 } 604 605 /* 606 * Update the thread's priority when the associated process's user 607 * priority changes. 608 */ 609 static void 610 resetpriority_thread(struct thread *td) 611 { 612 613 /* Only change threads with a time sharing user priority. */ 614 if (td->td_priority < PRI_MIN_TIMESHARE || 615 td->td_priority > PRI_MAX_TIMESHARE) 616 return; 617 618 /* XXX the whole needresched thing is broken, but not silly. */ 619 maybe_resched(td); 620 621 sched_prio(td, td->td_user_pri); 622 } 623 624 /* ARGSUSED */ 625 static void 626 sched_setup(void *dummy) 627 { 628 setup_runqs(); 629 630 if (sched_quantum == 0) 631 sched_quantum = SCHED_QUANTUM; 632 hogticks = 2 * sched_quantum; 633 634 /* Account for thread0. */ 635 sched_load_add(); 636 } 637 638 /* External interfaces start here */ 639 640 /* 641 * Very early in the boot some setup of scheduler-specific 642 * parts of proc0 and of some scheduler resources needs to be done. 643 * Called from: 644 * proc0_init() 645 */ 646 void 647 schedinit(void) 648 { 649 /* 650 * Set up the scheduler specific parts of proc0. 651 */ 652 proc0.p_sched = NULL; /* XXX */ 653 thread0.td_sched = &td_sched0; 654 thread0.td_lock = &sched_lock; 655 mtx_init(&sched_lock, "sched lock", NULL, MTX_SPIN | MTX_RECURSE); 656 } 657 658 int 659 sched_runnable(void) 660 { 661 #ifdef SMP 662 return runq_check(&runq) + runq_check(&runq_pcpu[PCPU_GET(cpuid)]); 663 #else 664 return runq_check(&runq); 665 #endif 666 } 667 668 int 669 sched_rr_interval(void) 670 { 671 if (sched_quantum == 0) 672 sched_quantum = SCHED_QUANTUM; 673 return (sched_quantum); 674 } 675 676 /* 677 * We adjust the priority of the current process. The priority of 678 * a process gets worse as it accumulates CPU time. The cpu usage 679 * estimator (td_estcpu) is increased here. resetpriority() will 680 * compute a different priority each time td_estcpu increases by 681 * INVERSE_ESTCPU_WEIGHT 682 * (until MAXPRI is reached). The cpu usage estimator ramps up 683 * quite quickly when the process is running (linearly), and decays 684 * away exponentially, at a rate which is proportionally slower when 685 * the system is busy. The basic principle is that the system will 686 * 90% forget that the process used a lot of CPU time in 5 * loadav 687 * seconds. This causes the system to favor processes which haven't 688 * run much recently, and to round-robin among other processes. 689 */ 690 void 691 sched_clock(struct thread *td) 692 { 693 struct pcpuidlestat *stat; 694 struct td_sched *ts; 695 696 THREAD_LOCK_ASSERT(td, MA_OWNED); 697 ts = td->td_sched; 698 699 ts->ts_cpticks++; 700 td->td_estcpu = ESTCPULIM(td->td_estcpu + 1); 701 if ((td->td_estcpu % INVERSE_ESTCPU_WEIGHT) == 0) { 702 resetpriority(td); 703 resetpriority_thread(td); 704 } 705 706 /* 707 * Force a context switch if the current thread has used up a full 708 * quantum (default quantum is 100ms). 709 */ 710 if (!TD_IS_IDLETHREAD(td) && 711 ticks - PCPU_GET(switchticks) >= sched_quantum) 712 td->td_flags |= TDF_NEEDRESCHED; 713 714 stat = DPCPU_PTR(idlestat); 715 stat->oldidlecalls = stat->idlecalls; 716 stat->idlecalls = 0; 717 } 718 719 /* 720 * Charge child's scheduling CPU usage to parent. 721 */ 722 void 723 sched_exit(struct proc *p, struct thread *td) 724 { 725 726 KTR_STATE1(KTR_SCHED, "thread", sched_tdname(td), "proc exit", 727 "prio:td", td->td_priority); 728 729 PROC_LOCK_ASSERT(p, MA_OWNED); 730 sched_exit_thread(FIRST_THREAD_IN_PROC(p), td); 731 } 732 733 void 734 sched_exit_thread(struct thread *td, struct thread *child) 735 { 736 737 KTR_STATE1(KTR_SCHED, "thread", sched_tdname(child), "exit", 738 "prio:td", child->td_priority); 739 thread_lock(td); 740 td->td_estcpu = ESTCPULIM(td->td_estcpu + child->td_estcpu); 741 thread_unlock(td); 742 thread_lock(child); 743 if ((child->td_flags & TDF_NOLOAD) == 0) 744 sched_load_rem(); 745 thread_unlock(child); 746 } 747 748 void 749 sched_fork(struct thread *td, struct thread *childtd) 750 { 751 sched_fork_thread(td, childtd); 752 } 753 754 void 755 sched_fork_thread(struct thread *td, struct thread *childtd) 756 { 757 struct td_sched *ts; 758 759 childtd->td_estcpu = td->td_estcpu; 760 childtd->td_lock = &sched_lock; 761 childtd->td_cpuset = cpuset_ref(td->td_cpuset); 762 ts = childtd->td_sched; 763 bzero(ts, sizeof(*ts)); 764 ts->ts_flags |= (td->td_sched->ts_flags & TSF_AFFINITY); 765 } 766 767 void 768 sched_nice(struct proc *p, int nice) 769 { 770 struct thread *td; 771 772 PROC_LOCK_ASSERT(p, MA_OWNED); 773 p->p_nice = nice; 774 FOREACH_THREAD_IN_PROC(p, td) { 775 thread_lock(td); 776 resetpriority(td); 777 resetpriority_thread(td); 778 thread_unlock(td); 779 } 780 } 781 782 void 783 sched_class(struct thread *td, int class) 784 { 785 THREAD_LOCK_ASSERT(td, MA_OWNED); 786 td->td_pri_class = class; 787 } 788 789 /* 790 * Adjust the priority of a thread. 791 */ 792 static void 793 sched_priority(struct thread *td, u_char prio) 794 { 795 796 797 KTR_POINT3(KTR_SCHED, "thread", sched_tdname(td), "priority change", 798 "prio:%d", td->td_priority, "new prio:%d", prio, KTR_ATTR_LINKED, 799 sched_tdname(curthread)); 800 if (td != curthread && prio > td->td_priority) { 801 KTR_POINT3(KTR_SCHED, "thread", sched_tdname(curthread), 802 "lend prio", "prio:%d", td->td_priority, "new prio:%d", 803 prio, KTR_ATTR_LINKED, sched_tdname(td)); 804 } 805 THREAD_LOCK_ASSERT(td, MA_OWNED); 806 if (td->td_priority == prio) 807 return; 808 td->td_priority = prio; 809 if (TD_ON_RUNQ(td) && td->td_rqindex != (prio / RQ_PPQ)) { 810 sched_rem(td); 811 sched_add(td, SRQ_BORING); 812 } 813 } 814 815 /* 816 * Update a thread's priority when it is lent another thread's 817 * priority. 818 */ 819 void 820 sched_lend_prio(struct thread *td, u_char prio) 821 { 822 823 td->td_flags |= TDF_BORROWING; 824 sched_priority(td, prio); 825 } 826 827 /* 828 * Restore a thread's priority when priority propagation is 829 * over. The prio argument is the minimum priority the thread 830 * needs to have to satisfy other possible priority lending 831 * requests. If the thread's regulary priority is less 832 * important than prio the thread will keep a priority boost 833 * of prio. 834 */ 835 void 836 sched_unlend_prio(struct thread *td, u_char prio) 837 { 838 u_char base_pri; 839 840 if (td->td_base_pri >= PRI_MIN_TIMESHARE && 841 td->td_base_pri <= PRI_MAX_TIMESHARE) 842 base_pri = td->td_user_pri; 843 else 844 base_pri = td->td_base_pri; 845 if (prio >= base_pri) { 846 td->td_flags &= ~TDF_BORROWING; 847 sched_prio(td, base_pri); 848 } else 849 sched_lend_prio(td, prio); 850 } 851 852 void 853 sched_prio(struct thread *td, u_char prio) 854 { 855 u_char oldprio; 856 857 /* First, update the base priority. */ 858 td->td_base_pri = prio; 859 860 /* 861 * If the thread is borrowing another thread's priority, don't ever 862 * lower the priority. 863 */ 864 if (td->td_flags & TDF_BORROWING && td->td_priority < prio) 865 return; 866 867 /* Change the real priority. */ 868 oldprio = td->td_priority; 869 sched_priority(td, prio); 870 871 /* 872 * If the thread is on a turnstile, then let the turnstile update 873 * its state. 874 */ 875 if (TD_ON_LOCK(td) && oldprio != prio) 876 turnstile_adjust(td, oldprio); 877 } 878 879 void 880 sched_user_prio(struct thread *td, u_char prio) 881 { 882 883 THREAD_LOCK_ASSERT(td, MA_OWNED); 884 td->td_base_user_pri = prio; 885 if (td->td_lend_user_pri <= prio) 886 return; 887 td->td_user_pri = prio; 888 } 889 890 void 891 sched_lend_user_prio(struct thread *td, u_char prio) 892 { 893 894 THREAD_LOCK_ASSERT(td, MA_OWNED); 895 if (prio < td->td_lend_user_pri) 896 td->td_lend_user_pri = prio; 897 if (prio < td->td_user_pri) 898 td->td_user_pri = prio; 899 } 900 901 void 902 sched_unlend_user_prio(struct thread *td, u_char prio) 903 { 904 u_char base_pri; 905 906 THREAD_LOCK_ASSERT(td, MA_OWNED); 907 base_pri = td->td_base_user_pri; 908 td->td_lend_user_pri = prio; 909 if (prio > base_pri) 910 td->td_user_pri = base_pri; 911 else 912 td->td_user_pri = prio; 913 } 914 915 void 916 sched_sleep(struct thread *td, int pri) 917 { 918 919 THREAD_LOCK_ASSERT(td, MA_OWNED); 920 td->td_slptick = ticks; 921 td->td_sched->ts_slptime = 0; 922 if (pri) 923 sched_prio(td, pri); 924 if (TD_IS_SUSPENDED(td) || pri >= PSOCK) 925 td->td_flags |= TDF_CANSWAP; 926 } 927 928 void 929 sched_switch(struct thread *td, struct thread *newtd, int flags) 930 { 931 struct mtx *tmtx; 932 struct td_sched *ts; 933 struct proc *p; 934 935 tmtx = NULL; 936 ts = td->td_sched; 937 p = td->td_proc; 938 939 THREAD_LOCK_ASSERT(td, MA_OWNED); 940 941 /* 942 * Switch to the sched lock to fix things up and pick 943 * a new thread. 944 * Block the td_lock in order to avoid breaking the critical path. 945 */ 946 if (td->td_lock != &sched_lock) { 947 mtx_lock_spin(&sched_lock); 948 tmtx = thread_lock_block(td); 949 } 950 951 if ((td->td_flags & TDF_NOLOAD) == 0) 952 sched_load_rem(); 953 954 if (newtd) { 955 MPASS(newtd->td_lock == &sched_lock); 956 newtd->td_flags |= (td->td_flags & TDF_NEEDRESCHED); 957 } 958 959 td->td_lastcpu = td->td_oncpu; 960 td->td_flags &= ~TDF_NEEDRESCHED; 961 td->td_owepreempt = 0; 962 td->td_oncpu = NOCPU; 963 964 /* 965 * At the last moment, if this thread is still marked RUNNING, 966 * then put it back on the run queue as it has not been suspended 967 * or stopped or any thing else similar. We never put the idle 968 * threads on the run queue, however. 969 */ 970 if (td->td_flags & TDF_IDLETD) { 971 TD_SET_CAN_RUN(td); 972 #ifdef SMP 973 idle_cpus_mask &= ~PCPU_GET(cpumask); 974 #endif 975 } else { 976 if (TD_IS_RUNNING(td)) { 977 /* Put us back on the run queue. */ 978 sched_add(td, (flags & SW_PREEMPT) ? 979 SRQ_OURSELF|SRQ_YIELDING|SRQ_PREEMPTED : 980 SRQ_OURSELF|SRQ_YIELDING); 981 } 982 } 983 if (newtd) { 984 /* 985 * The thread we are about to run needs to be counted 986 * as if it had been added to the run queue and selected. 987 * It came from: 988 * * A preemption 989 * * An upcall 990 * * A followon 991 */ 992 KASSERT((newtd->td_inhibitors == 0), 993 ("trying to run inhibited thread")); 994 newtd->td_flags |= TDF_DIDRUN; 995 TD_SET_RUNNING(newtd); 996 if ((newtd->td_flags & TDF_NOLOAD) == 0) 997 sched_load_add(); 998 } else { 999 newtd = choosethread(); 1000 MPASS(newtd->td_lock == &sched_lock); 1001 } 1002 1003 if (td != newtd) { 1004 #ifdef HWPMC_HOOKS 1005 if (PMC_PROC_IS_USING_PMCS(td->td_proc)) 1006 PMC_SWITCH_CONTEXT(td, PMC_FN_CSW_OUT); 1007 #endif 1008 /* I feel sleepy */ 1009 lock_profile_release_lock(&sched_lock.lock_object); 1010 #ifdef KDTRACE_HOOKS 1011 /* 1012 * If DTrace has set the active vtime enum to anything 1013 * other than INACTIVE (0), then it should have set the 1014 * function to call. 1015 */ 1016 if (dtrace_vtime_active) 1017 (*dtrace_vtime_switch_func)(newtd); 1018 #endif 1019 1020 cpu_switch(td, newtd, tmtx != NULL ? tmtx : td->td_lock); 1021 lock_profile_obtain_lock_success(&sched_lock.lock_object, 1022 0, 0, __FILE__, __LINE__); 1023 /* 1024 * Where am I? What year is it? 1025 * We are in the same thread that went to sleep above, 1026 * but any amount of time may have passed. All our context 1027 * will still be available as will local variables. 1028 * PCPU values however may have changed as we may have 1029 * changed CPU so don't trust cached values of them. 1030 * New threads will go to fork_exit() instead of here 1031 * so if you change things here you may need to change 1032 * things there too. 1033 * 1034 * If the thread above was exiting it will never wake 1035 * up again here, so either it has saved everything it 1036 * needed to, or the thread_wait() or wait() will 1037 * need to reap it. 1038 */ 1039 #ifdef HWPMC_HOOKS 1040 if (PMC_PROC_IS_USING_PMCS(td->td_proc)) 1041 PMC_SWITCH_CONTEXT(td, PMC_FN_CSW_IN); 1042 #endif 1043 } 1044 1045 #ifdef SMP 1046 if (td->td_flags & TDF_IDLETD) 1047 idle_cpus_mask |= PCPU_GET(cpumask); 1048 #endif 1049 sched_lock.mtx_lock = (uintptr_t)td; 1050 td->td_oncpu = PCPU_GET(cpuid); 1051 MPASS(td->td_lock == &sched_lock); 1052 } 1053 1054 void 1055 sched_wakeup(struct thread *td) 1056 { 1057 struct td_sched *ts; 1058 1059 THREAD_LOCK_ASSERT(td, MA_OWNED); 1060 ts = td->td_sched; 1061 td->td_flags &= ~TDF_CANSWAP; 1062 if (ts->ts_slptime > 1) { 1063 updatepri(td); 1064 resetpriority(td); 1065 } 1066 td->td_slptick = 0; 1067 ts->ts_slptime = 0; 1068 sched_add(td, SRQ_BORING); 1069 } 1070 1071 #ifdef SMP 1072 static int 1073 forward_wakeup(int cpunum) 1074 { 1075 struct pcpu *pc; 1076 cpumask_t dontuse, id, map, map2, map3, me; 1077 1078 mtx_assert(&sched_lock, MA_OWNED); 1079 1080 CTR0(KTR_RUNQ, "forward_wakeup()"); 1081 1082 if ((!forward_wakeup_enabled) || 1083 (forward_wakeup_use_mask == 0 && forward_wakeup_use_loop == 0)) 1084 return (0); 1085 if (!smp_started || cold || panicstr) 1086 return (0); 1087 1088 forward_wakeups_requested++; 1089 1090 /* 1091 * Check the idle mask we received against what we calculated 1092 * before in the old version. 1093 */ 1094 me = PCPU_GET(cpumask); 1095 1096 /* Don't bother if we should be doing it ourself. */ 1097 if ((me & idle_cpus_mask) && (cpunum == NOCPU || me == (1 << cpunum))) 1098 return (0); 1099 1100 dontuse = me | stopped_cpus | hlt_cpus_mask; 1101 map3 = 0; 1102 if (forward_wakeup_use_loop) { 1103 SLIST_FOREACH(pc, &cpuhead, pc_allcpu) { 1104 id = pc->pc_cpumask; 1105 if ((id & dontuse) == 0 && 1106 pc->pc_curthread == pc->pc_idlethread) { 1107 map3 |= id; 1108 } 1109 } 1110 } 1111 1112 if (forward_wakeup_use_mask) { 1113 map = 0; 1114 map = idle_cpus_mask & ~dontuse; 1115 1116 /* If they are both on, compare and use loop if different. */ 1117 if (forward_wakeup_use_loop) { 1118 if (map != map3) { 1119 printf("map (%02X) != map3 (%02X)\n", map, 1120 map3); 1121 map = map3; 1122 } 1123 } 1124 } else { 1125 map = map3; 1126 } 1127 1128 /* If we only allow a specific CPU, then mask off all the others. */ 1129 if (cpunum != NOCPU) { 1130 KASSERT((cpunum <= mp_maxcpus),("forward_wakeup: bad cpunum.")); 1131 map &= (1 << cpunum); 1132 } else { 1133 /* Try choose an idle die. */ 1134 if (forward_wakeup_use_htt) { 1135 map2 = (map & (map >> 1)) & 0x5555; 1136 if (map2) { 1137 map = map2; 1138 } 1139 } 1140 1141 /* Set only one bit. */ 1142 if (forward_wakeup_use_single) { 1143 map = map & ((~map) + 1); 1144 } 1145 } 1146 if (map) { 1147 forward_wakeups_delivered++; 1148 SLIST_FOREACH(pc, &cpuhead, pc_allcpu) { 1149 id = pc->pc_cpumask; 1150 if ((map & id) == 0) 1151 continue; 1152 if (cpu_idle_wakeup(pc->pc_cpuid)) 1153 map &= ~id; 1154 } 1155 if (map) 1156 ipi_selected(map, IPI_AST); 1157 return (1); 1158 } 1159 if (cpunum == NOCPU) 1160 printf("forward_wakeup: Idle processor not found\n"); 1161 return (0); 1162 } 1163 1164 static void 1165 kick_other_cpu(int pri, int cpuid) 1166 { 1167 struct pcpu *pcpu; 1168 int cpri; 1169 1170 pcpu = pcpu_find(cpuid); 1171 if (idle_cpus_mask & pcpu->pc_cpumask) { 1172 forward_wakeups_delivered++; 1173 if (!cpu_idle_wakeup(cpuid)) 1174 ipi_cpu(cpuid, IPI_AST); 1175 return; 1176 } 1177 1178 cpri = pcpu->pc_curthread->td_priority; 1179 if (pri >= cpri) 1180 return; 1181 1182 #if defined(IPI_PREEMPTION) && defined(PREEMPTION) 1183 #if !defined(FULL_PREEMPTION) 1184 if (pri <= PRI_MAX_ITHD) 1185 #endif /* ! FULL_PREEMPTION */ 1186 { 1187 ipi_cpu(cpuid, IPI_PREEMPT); 1188 return; 1189 } 1190 #endif /* defined(IPI_PREEMPTION) && defined(PREEMPTION) */ 1191 1192 pcpu->pc_curthread->td_flags |= TDF_NEEDRESCHED; 1193 ipi_cpu(cpuid, IPI_AST); 1194 return; 1195 } 1196 #endif /* SMP */ 1197 1198 #ifdef SMP 1199 static int 1200 sched_pickcpu(struct thread *td) 1201 { 1202 int best, cpu; 1203 1204 mtx_assert(&sched_lock, MA_OWNED); 1205 1206 if (THREAD_CAN_SCHED(td, td->td_lastcpu)) 1207 best = td->td_lastcpu; 1208 else 1209 best = NOCPU; 1210 CPU_FOREACH(cpu) { 1211 if (!THREAD_CAN_SCHED(td, cpu)) 1212 continue; 1213 1214 if (best == NOCPU) 1215 best = cpu; 1216 else if (runq_length[cpu] < runq_length[best]) 1217 best = cpu; 1218 } 1219 KASSERT(best != NOCPU, ("no valid CPUs")); 1220 1221 return (best); 1222 } 1223 #endif 1224 1225 void 1226 sched_add(struct thread *td, int flags) 1227 #ifdef SMP 1228 { 1229 struct td_sched *ts; 1230 int forwarded = 0; 1231 int cpu; 1232 int single_cpu = 0; 1233 1234 ts = td->td_sched; 1235 THREAD_LOCK_ASSERT(td, MA_OWNED); 1236 KASSERT((td->td_inhibitors == 0), 1237 ("sched_add: trying to run inhibited thread")); 1238 KASSERT((TD_CAN_RUN(td) || TD_IS_RUNNING(td)), 1239 ("sched_add: bad thread state")); 1240 KASSERT(td->td_flags & TDF_INMEM, 1241 ("sched_add: thread swapped out")); 1242 1243 KTR_STATE2(KTR_SCHED, "thread", sched_tdname(td), "runq add", 1244 "prio:%d", td->td_priority, KTR_ATTR_LINKED, 1245 sched_tdname(curthread)); 1246 KTR_POINT1(KTR_SCHED, "thread", sched_tdname(curthread), "wokeup", 1247 KTR_ATTR_LINKED, sched_tdname(td)); 1248 1249 1250 /* 1251 * Now that the thread is moving to the run-queue, set the lock 1252 * to the scheduler's lock. 1253 */ 1254 if (td->td_lock != &sched_lock) { 1255 mtx_lock_spin(&sched_lock); 1256 thread_lock_set(td, &sched_lock); 1257 } 1258 TD_SET_RUNQ(td); 1259 1260 if (td->td_pinned != 0) { 1261 cpu = td->td_lastcpu; 1262 ts->ts_runq = &runq_pcpu[cpu]; 1263 single_cpu = 1; 1264 CTR3(KTR_RUNQ, 1265 "sched_add: Put td_sched:%p(td:%p) on cpu%d runq", ts, td, 1266 cpu); 1267 } else if (td->td_flags & TDF_BOUND) { 1268 /* Find CPU from bound runq. */ 1269 KASSERT(SKE_RUNQ_PCPU(ts), 1270 ("sched_add: bound td_sched not on cpu runq")); 1271 cpu = ts->ts_runq - &runq_pcpu[0]; 1272 single_cpu = 1; 1273 CTR3(KTR_RUNQ, 1274 "sched_add: Put td_sched:%p(td:%p) on cpu%d runq", ts, td, 1275 cpu); 1276 } else if (ts->ts_flags & TSF_AFFINITY) { 1277 /* Find a valid CPU for our cpuset */ 1278 cpu = sched_pickcpu(td); 1279 ts->ts_runq = &runq_pcpu[cpu]; 1280 single_cpu = 1; 1281 CTR3(KTR_RUNQ, 1282 "sched_add: Put td_sched:%p(td:%p) on cpu%d runq", ts, td, 1283 cpu); 1284 } else { 1285 CTR2(KTR_RUNQ, 1286 "sched_add: adding td_sched:%p (td:%p) to gbl runq", ts, 1287 td); 1288 cpu = NOCPU; 1289 ts->ts_runq = &runq; 1290 } 1291 1292 if (single_cpu && (cpu != PCPU_GET(cpuid))) { 1293 kick_other_cpu(td->td_priority, cpu); 1294 } else { 1295 if (!single_cpu) { 1296 cpumask_t me = PCPU_GET(cpumask); 1297 cpumask_t idle = idle_cpus_mask & me; 1298 1299 if (!idle && ((flags & SRQ_INTR) == 0) && 1300 (idle_cpus_mask & ~(hlt_cpus_mask | me))) 1301 forwarded = forward_wakeup(cpu); 1302 } 1303 1304 if (!forwarded) { 1305 if ((flags & SRQ_YIELDING) == 0 && maybe_preempt(td)) 1306 return; 1307 else 1308 maybe_resched(td); 1309 } 1310 } 1311 1312 if ((td->td_flags & TDF_NOLOAD) == 0) 1313 sched_load_add(); 1314 runq_add(ts->ts_runq, td, flags); 1315 if (cpu != NOCPU) 1316 runq_length[cpu]++; 1317 } 1318 #else /* SMP */ 1319 { 1320 struct td_sched *ts; 1321 1322 ts = td->td_sched; 1323 THREAD_LOCK_ASSERT(td, MA_OWNED); 1324 KASSERT((td->td_inhibitors == 0), 1325 ("sched_add: trying to run inhibited thread")); 1326 KASSERT((TD_CAN_RUN(td) || TD_IS_RUNNING(td)), 1327 ("sched_add: bad thread state")); 1328 KASSERT(td->td_flags & TDF_INMEM, 1329 ("sched_add: thread swapped out")); 1330 KTR_STATE2(KTR_SCHED, "thread", sched_tdname(td), "runq add", 1331 "prio:%d", td->td_priority, KTR_ATTR_LINKED, 1332 sched_tdname(curthread)); 1333 KTR_POINT1(KTR_SCHED, "thread", sched_tdname(curthread), "wokeup", 1334 KTR_ATTR_LINKED, sched_tdname(td)); 1335 1336 /* 1337 * Now that the thread is moving to the run-queue, set the lock 1338 * to the scheduler's lock. 1339 */ 1340 if (td->td_lock != &sched_lock) { 1341 mtx_lock_spin(&sched_lock); 1342 thread_lock_set(td, &sched_lock); 1343 } 1344 TD_SET_RUNQ(td); 1345 CTR2(KTR_RUNQ, "sched_add: adding td_sched:%p (td:%p) to runq", ts, td); 1346 ts->ts_runq = &runq; 1347 1348 /* 1349 * If we are yielding (on the way out anyhow) or the thread 1350 * being saved is US, then don't try be smart about preemption 1351 * or kicking off another CPU as it won't help and may hinder. 1352 * In the YIEDLING case, we are about to run whoever is being 1353 * put in the queue anyhow, and in the OURSELF case, we are 1354 * puting ourself on the run queue which also only happens 1355 * when we are about to yield. 1356 */ 1357 if ((flags & SRQ_YIELDING) == 0) { 1358 if (maybe_preempt(td)) 1359 return; 1360 } 1361 if ((td->td_flags & TDF_NOLOAD) == 0) 1362 sched_load_add(); 1363 runq_add(ts->ts_runq, td, flags); 1364 maybe_resched(td); 1365 } 1366 #endif /* SMP */ 1367 1368 void 1369 sched_rem(struct thread *td) 1370 { 1371 struct td_sched *ts; 1372 1373 ts = td->td_sched; 1374 KASSERT(td->td_flags & TDF_INMEM, 1375 ("sched_rem: thread swapped out")); 1376 KASSERT(TD_ON_RUNQ(td), 1377 ("sched_rem: thread not on run queue")); 1378 mtx_assert(&sched_lock, MA_OWNED); 1379 KTR_STATE2(KTR_SCHED, "thread", sched_tdname(td), "runq rem", 1380 "prio:%d", td->td_priority, KTR_ATTR_LINKED, 1381 sched_tdname(curthread)); 1382 1383 if ((td->td_flags & TDF_NOLOAD) == 0) 1384 sched_load_rem(); 1385 #ifdef SMP 1386 if (ts->ts_runq != &runq) 1387 runq_length[ts->ts_runq - runq_pcpu]--; 1388 #endif 1389 runq_remove(ts->ts_runq, td); 1390 TD_SET_CAN_RUN(td); 1391 } 1392 1393 /* 1394 * Select threads to run. Note that running threads still consume a 1395 * slot. 1396 */ 1397 struct thread * 1398 sched_choose(void) 1399 { 1400 struct thread *td; 1401 struct runq *rq; 1402 1403 mtx_assert(&sched_lock, MA_OWNED); 1404 #ifdef SMP 1405 struct thread *tdcpu; 1406 1407 rq = &runq; 1408 td = runq_choose_fuzz(&runq, runq_fuzz); 1409 tdcpu = runq_choose(&runq_pcpu[PCPU_GET(cpuid)]); 1410 1411 if (td == NULL || 1412 (tdcpu != NULL && 1413 tdcpu->td_priority < td->td_priority)) { 1414 CTR2(KTR_RUNQ, "choosing td %p from pcpu runq %d", tdcpu, 1415 PCPU_GET(cpuid)); 1416 td = tdcpu; 1417 rq = &runq_pcpu[PCPU_GET(cpuid)]; 1418 } else { 1419 CTR1(KTR_RUNQ, "choosing td_sched %p from main runq", td); 1420 } 1421 1422 #else 1423 rq = &runq; 1424 td = runq_choose(&runq); 1425 #endif 1426 1427 if (td) { 1428 #ifdef SMP 1429 if (td == tdcpu) 1430 runq_length[PCPU_GET(cpuid)]--; 1431 #endif 1432 runq_remove(rq, td); 1433 td->td_flags |= TDF_DIDRUN; 1434 1435 KASSERT(td->td_flags & TDF_INMEM, 1436 ("sched_choose: thread swapped out")); 1437 return (td); 1438 } 1439 return (PCPU_GET(idlethread)); 1440 } 1441 1442 void 1443 sched_preempt(struct thread *td) 1444 { 1445 thread_lock(td); 1446 if (td->td_critnest > 1) 1447 td->td_owepreempt = 1; 1448 else 1449 mi_switch(SW_INVOL | SW_PREEMPT | SWT_PREEMPT, NULL); 1450 thread_unlock(td); 1451 } 1452 1453 void 1454 sched_userret(struct thread *td) 1455 { 1456 /* 1457 * XXX we cheat slightly on the locking here to avoid locking in 1458 * the usual case. Setting td_priority here is essentially an 1459 * incomplete workaround for not setting it properly elsewhere. 1460 * Now that some interrupt handlers are threads, not setting it 1461 * properly elsewhere can clobber it in the window between setting 1462 * it here and returning to user mode, so don't waste time setting 1463 * it perfectly here. 1464 */ 1465 KASSERT((td->td_flags & TDF_BORROWING) == 0, 1466 ("thread with borrowed priority returning to userland")); 1467 if (td->td_priority != td->td_user_pri) { 1468 thread_lock(td); 1469 td->td_priority = td->td_user_pri; 1470 td->td_base_pri = td->td_user_pri; 1471 thread_unlock(td); 1472 } 1473 } 1474 1475 void 1476 sched_bind(struct thread *td, int cpu) 1477 { 1478 struct td_sched *ts; 1479 1480 THREAD_LOCK_ASSERT(td, MA_OWNED|MA_NOTRECURSED); 1481 KASSERT(td == curthread, ("sched_bind: can only bind curthread")); 1482 1483 ts = td->td_sched; 1484 1485 td->td_flags |= TDF_BOUND; 1486 #ifdef SMP 1487 ts->ts_runq = &runq_pcpu[cpu]; 1488 if (PCPU_GET(cpuid) == cpu) 1489 return; 1490 1491 mi_switch(SW_VOL, NULL); 1492 #endif 1493 } 1494 1495 void 1496 sched_unbind(struct thread* td) 1497 { 1498 THREAD_LOCK_ASSERT(td, MA_OWNED); 1499 KASSERT(td == curthread, ("sched_unbind: can only bind curthread")); 1500 td->td_flags &= ~TDF_BOUND; 1501 } 1502 1503 int 1504 sched_is_bound(struct thread *td) 1505 { 1506 THREAD_LOCK_ASSERT(td, MA_OWNED); 1507 return (td->td_flags & TDF_BOUND); 1508 } 1509 1510 void 1511 sched_relinquish(struct thread *td) 1512 { 1513 thread_lock(td); 1514 mi_switch(SW_VOL | SWT_RELINQUISH, NULL); 1515 thread_unlock(td); 1516 } 1517 1518 int 1519 sched_load(void) 1520 { 1521 return (sched_tdcnt); 1522 } 1523 1524 int 1525 sched_sizeof_proc(void) 1526 { 1527 return (sizeof(struct proc)); 1528 } 1529 1530 int 1531 sched_sizeof_thread(void) 1532 { 1533 return (sizeof(struct thread) + sizeof(struct td_sched)); 1534 } 1535 1536 fixpt_t 1537 sched_pctcpu(struct thread *td) 1538 { 1539 struct td_sched *ts; 1540 1541 THREAD_LOCK_ASSERT(td, MA_OWNED); 1542 ts = td->td_sched; 1543 return (ts->ts_pctcpu); 1544 } 1545 1546 void 1547 sched_tick(int cnt) 1548 { 1549 } 1550 1551 /* 1552 * The actual idle process. 1553 */ 1554 void 1555 sched_idletd(void *dummy) 1556 { 1557 struct pcpuidlestat *stat; 1558 1559 stat = DPCPU_PTR(idlestat); 1560 for (;;) { 1561 mtx_assert(&Giant, MA_NOTOWNED); 1562 1563 while (sched_runnable() == 0) { 1564 cpu_idle(stat->idlecalls + stat->oldidlecalls > 64); 1565 stat->idlecalls++; 1566 } 1567 1568 mtx_lock_spin(&sched_lock); 1569 mi_switch(SW_VOL | SWT_IDLE, NULL); 1570 mtx_unlock_spin(&sched_lock); 1571 } 1572 } 1573 1574 /* 1575 * A CPU is entering for the first time or a thread is exiting. 1576 */ 1577 void 1578 sched_throw(struct thread *td) 1579 { 1580 /* 1581 * Correct spinlock nesting. The idle thread context that we are 1582 * borrowing was created so that it would start out with a single 1583 * spin lock (sched_lock) held in fork_trampoline(). Since we've 1584 * explicitly acquired locks in this function, the nesting count 1585 * is now 2 rather than 1. Since we are nested, calling 1586 * spinlock_exit() will simply adjust the counts without allowing 1587 * spin lock using code to interrupt us. 1588 */ 1589 if (td == NULL) { 1590 mtx_lock_spin(&sched_lock); 1591 spinlock_exit(); 1592 } else { 1593 lock_profile_release_lock(&sched_lock.lock_object); 1594 MPASS(td->td_lock == &sched_lock); 1595 } 1596 mtx_assert(&sched_lock, MA_OWNED); 1597 KASSERT(curthread->td_md.md_spinlock_count == 1, ("invalid count")); 1598 PCPU_SET(switchtime, cpu_ticks()); 1599 PCPU_SET(switchticks, ticks); 1600 cpu_throw(td, choosethread()); /* doesn't return */ 1601 } 1602 1603 void 1604 sched_fork_exit(struct thread *td) 1605 { 1606 1607 /* 1608 * Finish setting up thread glue so that it begins execution in a 1609 * non-nested critical section with sched_lock held but not recursed. 1610 */ 1611 td->td_oncpu = PCPU_GET(cpuid); 1612 sched_lock.mtx_lock = (uintptr_t)td; 1613 lock_profile_obtain_lock_success(&sched_lock.lock_object, 1614 0, 0, __FILE__, __LINE__); 1615 THREAD_LOCK_ASSERT(td, MA_OWNED | MA_NOTRECURSED); 1616 } 1617 1618 char * 1619 sched_tdname(struct thread *td) 1620 { 1621 #ifdef KTR 1622 struct td_sched *ts; 1623 1624 ts = td->td_sched; 1625 if (ts->ts_name[0] == '\0') 1626 snprintf(ts->ts_name, sizeof(ts->ts_name), 1627 "%s tid %d", td->td_name, td->td_tid); 1628 return (ts->ts_name); 1629 #else 1630 return (td->td_name); 1631 #endif 1632 } 1633 1634 void 1635 sched_affinity(struct thread *td) 1636 { 1637 #ifdef SMP 1638 struct td_sched *ts; 1639 int cpu; 1640 1641 THREAD_LOCK_ASSERT(td, MA_OWNED); 1642 1643 /* 1644 * Set the TSF_AFFINITY flag if there is at least one CPU this 1645 * thread can't run on. 1646 */ 1647 ts = td->td_sched; 1648 ts->ts_flags &= ~TSF_AFFINITY; 1649 CPU_FOREACH(cpu) { 1650 if (!THREAD_CAN_SCHED(td, cpu)) { 1651 ts->ts_flags |= TSF_AFFINITY; 1652 break; 1653 } 1654 } 1655 1656 /* 1657 * If this thread can run on all CPUs, nothing else to do. 1658 */ 1659 if (!(ts->ts_flags & TSF_AFFINITY)) 1660 return; 1661 1662 /* Pinned threads and bound threads should be left alone. */ 1663 if (td->td_pinned != 0 || td->td_flags & TDF_BOUND) 1664 return; 1665 1666 switch (td->td_state) { 1667 case TDS_RUNQ: 1668 /* 1669 * If we are on a per-CPU runqueue that is in the set, 1670 * then nothing needs to be done. 1671 */ 1672 if (ts->ts_runq != &runq && 1673 THREAD_CAN_SCHED(td, ts->ts_runq - runq_pcpu)) 1674 return; 1675 1676 /* Put this thread on a valid per-CPU runqueue. */ 1677 sched_rem(td); 1678 sched_add(td, SRQ_BORING); 1679 break; 1680 case TDS_RUNNING: 1681 /* 1682 * See if our current CPU is in the set. If not, force a 1683 * context switch. 1684 */ 1685 if (THREAD_CAN_SCHED(td, td->td_oncpu)) 1686 return; 1687 1688 td->td_flags |= TDF_NEEDRESCHED; 1689 if (td != curthread) 1690 ipi_cpu(cpu, IPI_AST); 1691 break; 1692 default: 1693 break; 1694 } 1695 #endif 1696 } 1697