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 u_char oldprio; 883 884 THREAD_LOCK_ASSERT(td, MA_OWNED); 885 td->td_base_user_pri = prio; 886 if (td->td_flags & TDF_UBORROWING && td->td_user_pri <= prio) 887 return; 888 oldprio = td->td_user_pri; 889 td->td_user_pri = prio; 890 } 891 892 void 893 sched_lend_user_prio(struct thread *td, u_char prio) 894 { 895 u_char oldprio; 896 897 THREAD_LOCK_ASSERT(td, MA_OWNED); 898 td->td_flags |= TDF_UBORROWING; 899 oldprio = td->td_user_pri; 900 td->td_user_pri = prio; 901 } 902 903 void 904 sched_unlend_user_prio(struct thread *td, u_char prio) 905 { 906 u_char base_pri; 907 908 THREAD_LOCK_ASSERT(td, MA_OWNED); 909 base_pri = td->td_base_user_pri; 910 if (prio >= base_pri) { 911 td->td_flags &= ~TDF_UBORROWING; 912 sched_user_prio(td, base_pri); 913 } else { 914 sched_lend_user_prio(td, prio); 915 } 916 } 917 918 void 919 sched_sleep(struct thread *td, int pri) 920 { 921 922 THREAD_LOCK_ASSERT(td, MA_OWNED); 923 td->td_slptick = ticks; 924 td->td_sched->ts_slptime = 0; 925 if (pri) 926 sched_prio(td, pri); 927 if (TD_IS_SUSPENDED(td) || pri >= PSOCK) 928 td->td_flags |= TDF_CANSWAP; 929 } 930 931 void 932 sched_switch(struct thread *td, struct thread *newtd, int flags) 933 { 934 struct mtx *tmtx; 935 struct td_sched *ts; 936 struct proc *p; 937 938 tmtx = NULL; 939 ts = td->td_sched; 940 p = td->td_proc; 941 942 THREAD_LOCK_ASSERT(td, MA_OWNED); 943 944 /* 945 * Switch to the sched lock to fix things up and pick 946 * a new thread. 947 * Block the td_lock in order to avoid breaking the critical path. 948 */ 949 if (td->td_lock != &sched_lock) { 950 mtx_lock_spin(&sched_lock); 951 tmtx = thread_lock_block(td); 952 } 953 954 if ((td->td_flags & TDF_NOLOAD) == 0) 955 sched_load_rem(); 956 957 if (newtd) { 958 MPASS(newtd->td_lock == &sched_lock); 959 newtd->td_flags |= (td->td_flags & TDF_NEEDRESCHED); 960 } 961 962 td->td_lastcpu = td->td_oncpu; 963 td->td_flags &= ~TDF_NEEDRESCHED; 964 td->td_owepreempt = 0; 965 td->td_oncpu = NOCPU; 966 967 /* 968 * At the last moment, if this thread is still marked RUNNING, 969 * then put it back on the run queue as it has not been suspended 970 * or stopped or any thing else similar. We never put the idle 971 * threads on the run queue, however. 972 */ 973 if (td->td_flags & TDF_IDLETD) { 974 TD_SET_CAN_RUN(td); 975 #ifdef SMP 976 idle_cpus_mask &= ~PCPU_GET(cpumask); 977 #endif 978 } else { 979 if (TD_IS_RUNNING(td)) { 980 /* Put us back on the run queue. */ 981 sched_add(td, (flags & SW_PREEMPT) ? 982 SRQ_OURSELF|SRQ_YIELDING|SRQ_PREEMPTED : 983 SRQ_OURSELF|SRQ_YIELDING); 984 } 985 } 986 if (newtd) { 987 /* 988 * The thread we are about to run needs to be counted 989 * as if it had been added to the run queue and selected. 990 * It came from: 991 * * A preemption 992 * * An upcall 993 * * A followon 994 */ 995 KASSERT((newtd->td_inhibitors == 0), 996 ("trying to run inhibited thread")); 997 newtd->td_flags |= TDF_DIDRUN; 998 TD_SET_RUNNING(newtd); 999 if ((newtd->td_flags & TDF_NOLOAD) == 0) 1000 sched_load_add(); 1001 } else { 1002 newtd = choosethread(); 1003 MPASS(newtd->td_lock == &sched_lock); 1004 } 1005 1006 if (td != newtd) { 1007 #ifdef HWPMC_HOOKS 1008 if (PMC_PROC_IS_USING_PMCS(td->td_proc)) 1009 PMC_SWITCH_CONTEXT(td, PMC_FN_CSW_OUT); 1010 #endif 1011 /* I feel sleepy */ 1012 lock_profile_release_lock(&sched_lock.lock_object); 1013 #ifdef KDTRACE_HOOKS 1014 /* 1015 * If DTrace has set the active vtime enum to anything 1016 * other than INACTIVE (0), then it should have set the 1017 * function to call. 1018 */ 1019 if (dtrace_vtime_active) 1020 (*dtrace_vtime_switch_func)(newtd); 1021 #endif 1022 1023 cpu_switch(td, newtd, tmtx != NULL ? tmtx : td->td_lock); 1024 lock_profile_obtain_lock_success(&sched_lock.lock_object, 1025 0, 0, __FILE__, __LINE__); 1026 /* 1027 * Where am I? What year is it? 1028 * We are in the same thread that went to sleep above, 1029 * but any amount of time may have passed. All our context 1030 * will still be available as will local variables. 1031 * PCPU values however may have changed as we may have 1032 * changed CPU so don't trust cached values of them. 1033 * New threads will go to fork_exit() instead of here 1034 * so if you change things here you may need to change 1035 * things there too. 1036 * 1037 * If the thread above was exiting it will never wake 1038 * up again here, so either it has saved everything it 1039 * needed to, or the thread_wait() or wait() will 1040 * need to reap it. 1041 */ 1042 #ifdef HWPMC_HOOKS 1043 if (PMC_PROC_IS_USING_PMCS(td->td_proc)) 1044 PMC_SWITCH_CONTEXT(td, PMC_FN_CSW_IN); 1045 #endif 1046 } 1047 1048 #ifdef SMP 1049 if (td->td_flags & TDF_IDLETD) 1050 idle_cpus_mask |= PCPU_GET(cpumask); 1051 #endif 1052 sched_lock.mtx_lock = (uintptr_t)td; 1053 td->td_oncpu = PCPU_GET(cpuid); 1054 MPASS(td->td_lock == &sched_lock); 1055 } 1056 1057 void 1058 sched_wakeup(struct thread *td) 1059 { 1060 struct td_sched *ts; 1061 1062 THREAD_LOCK_ASSERT(td, MA_OWNED); 1063 ts = td->td_sched; 1064 td->td_flags &= ~TDF_CANSWAP; 1065 if (ts->ts_slptime > 1) { 1066 updatepri(td); 1067 resetpriority(td); 1068 } 1069 td->td_slptick = 0; 1070 ts->ts_slptime = 0; 1071 sched_add(td, SRQ_BORING); 1072 } 1073 1074 #ifdef SMP 1075 static int 1076 forward_wakeup(int cpunum) 1077 { 1078 struct pcpu *pc; 1079 cpumask_t dontuse, id, map, map2, map3, me; 1080 1081 mtx_assert(&sched_lock, MA_OWNED); 1082 1083 CTR0(KTR_RUNQ, "forward_wakeup()"); 1084 1085 if ((!forward_wakeup_enabled) || 1086 (forward_wakeup_use_mask == 0 && forward_wakeup_use_loop == 0)) 1087 return (0); 1088 if (!smp_started || cold || panicstr) 1089 return (0); 1090 1091 forward_wakeups_requested++; 1092 1093 /* 1094 * Check the idle mask we received against what we calculated 1095 * before in the old version. 1096 */ 1097 me = PCPU_GET(cpumask); 1098 1099 /* Don't bother if we should be doing it ourself. */ 1100 if ((me & idle_cpus_mask) && (cpunum == NOCPU || me == (1 << cpunum))) 1101 return (0); 1102 1103 dontuse = me | stopped_cpus | hlt_cpus_mask; 1104 map3 = 0; 1105 if (forward_wakeup_use_loop) { 1106 SLIST_FOREACH(pc, &cpuhead, pc_allcpu) { 1107 id = pc->pc_cpumask; 1108 if ((id & dontuse) == 0 && 1109 pc->pc_curthread == pc->pc_idlethread) { 1110 map3 |= id; 1111 } 1112 } 1113 } 1114 1115 if (forward_wakeup_use_mask) { 1116 map = 0; 1117 map = idle_cpus_mask & ~dontuse; 1118 1119 /* If they are both on, compare and use loop if different. */ 1120 if (forward_wakeup_use_loop) { 1121 if (map != map3) { 1122 printf("map (%02X) != map3 (%02X)\n", map, 1123 map3); 1124 map = map3; 1125 } 1126 } 1127 } else { 1128 map = map3; 1129 } 1130 1131 /* If we only allow a specific CPU, then mask off all the others. */ 1132 if (cpunum != NOCPU) { 1133 KASSERT((cpunum <= mp_maxcpus),("forward_wakeup: bad cpunum.")); 1134 map &= (1 << cpunum); 1135 } else { 1136 /* Try choose an idle die. */ 1137 if (forward_wakeup_use_htt) { 1138 map2 = (map & (map >> 1)) & 0x5555; 1139 if (map2) { 1140 map = map2; 1141 } 1142 } 1143 1144 /* Set only one bit. */ 1145 if (forward_wakeup_use_single) { 1146 map = map & ((~map) + 1); 1147 } 1148 } 1149 if (map) { 1150 forward_wakeups_delivered++; 1151 SLIST_FOREACH(pc, &cpuhead, pc_allcpu) { 1152 id = pc->pc_cpumask; 1153 if ((map & id) == 0) 1154 continue; 1155 if (cpu_idle_wakeup(pc->pc_cpuid)) 1156 map &= ~id; 1157 } 1158 if (map) 1159 ipi_selected(map, IPI_AST); 1160 return (1); 1161 } 1162 if (cpunum == NOCPU) 1163 printf("forward_wakeup: Idle processor not found\n"); 1164 return (0); 1165 } 1166 1167 static void 1168 kick_other_cpu(int pri, int cpuid) 1169 { 1170 struct pcpu *pcpu; 1171 int cpri; 1172 1173 pcpu = pcpu_find(cpuid); 1174 if (idle_cpus_mask & pcpu->pc_cpumask) { 1175 forward_wakeups_delivered++; 1176 if (!cpu_idle_wakeup(cpuid)) 1177 ipi_cpu(cpuid, IPI_AST); 1178 return; 1179 } 1180 1181 cpri = pcpu->pc_curthread->td_priority; 1182 if (pri >= cpri) 1183 return; 1184 1185 #if defined(IPI_PREEMPTION) && defined(PREEMPTION) 1186 #if !defined(FULL_PREEMPTION) 1187 if (pri <= PRI_MAX_ITHD) 1188 #endif /* ! FULL_PREEMPTION */ 1189 { 1190 ipi_cpu(cpuid, IPI_PREEMPT); 1191 return; 1192 } 1193 #endif /* defined(IPI_PREEMPTION) && defined(PREEMPTION) */ 1194 1195 pcpu->pc_curthread->td_flags |= TDF_NEEDRESCHED; 1196 ipi_cpu(cpuid, IPI_AST); 1197 return; 1198 } 1199 #endif /* SMP */ 1200 1201 #ifdef SMP 1202 static int 1203 sched_pickcpu(struct thread *td) 1204 { 1205 int best, cpu; 1206 1207 mtx_assert(&sched_lock, MA_OWNED); 1208 1209 if (THREAD_CAN_SCHED(td, td->td_lastcpu)) 1210 best = td->td_lastcpu; 1211 else 1212 best = NOCPU; 1213 CPU_FOREACH(cpu) { 1214 if (!THREAD_CAN_SCHED(td, cpu)) 1215 continue; 1216 1217 if (best == NOCPU) 1218 best = cpu; 1219 else if (runq_length[cpu] < runq_length[best]) 1220 best = cpu; 1221 } 1222 KASSERT(best != NOCPU, ("no valid CPUs")); 1223 1224 return (best); 1225 } 1226 #endif 1227 1228 void 1229 sched_add(struct thread *td, int flags) 1230 #ifdef SMP 1231 { 1232 struct td_sched *ts; 1233 int forwarded = 0; 1234 int cpu; 1235 int single_cpu = 0; 1236 1237 ts = td->td_sched; 1238 THREAD_LOCK_ASSERT(td, MA_OWNED); 1239 KASSERT((td->td_inhibitors == 0), 1240 ("sched_add: trying to run inhibited thread")); 1241 KASSERT((TD_CAN_RUN(td) || TD_IS_RUNNING(td)), 1242 ("sched_add: bad thread state")); 1243 KASSERT(td->td_flags & TDF_INMEM, 1244 ("sched_add: thread swapped out")); 1245 1246 KTR_STATE2(KTR_SCHED, "thread", sched_tdname(td), "runq add", 1247 "prio:%d", td->td_priority, KTR_ATTR_LINKED, 1248 sched_tdname(curthread)); 1249 KTR_POINT1(KTR_SCHED, "thread", sched_tdname(curthread), "wokeup", 1250 KTR_ATTR_LINKED, sched_tdname(td)); 1251 1252 1253 /* 1254 * Now that the thread is moving to the run-queue, set the lock 1255 * to the scheduler's lock. 1256 */ 1257 if (td->td_lock != &sched_lock) { 1258 mtx_lock_spin(&sched_lock); 1259 thread_lock_set(td, &sched_lock); 1260 } 1261 TD_SET_RUNQ(td); 1262 1263 if (td->td_pinned != 0) { 1264 cpu = td->td_lastcpu; 1265 ts->ts_runq = &runq_pcpu[cpu]; 1266 single_cpu = 1; 1267 CTR3(KTR_RUNQ, 1268 "sched_add: Put td_sched:%p(td:%p) on cpu%d runq", ts, td, 1269 cpu); 1270 } else if (td->td_flags & TDF_BOUND) { 1271 /* Find CPU from bound runq. */ 1272 KASSERT(SKE_RUNQ_PCPU(ts), 1273 ("sched_add: bound td_sched not on cpu runq")); 1274 cpu = ts->ts_runq - &runq_pcpu[0]; 1275 single_cpu = 1; 1276 CTR3(KTR_RUNQ, 1277 "sched_add: Put td_sched:%p(td:%p) on cpu%d runq", ts, td, 1278 cpu); 1279 } else if (ts->ts_flags & TSF_AFFINITY) { 1280 /* Find a valid CPU for our cpuset */ 1281 cpu = sched_pickcpu(td); 1282 ts->ts_runq = &runq_pcpu[cpu]; 1283 single_cpu = 1; 1284 CTR3(KTR_RUNQ, 1285 "sched_add: Put td_sched:%p(td:%p) on cpu%d runq", ts, td, 1286 cpu); 1287 } else { 1288 CTR2(KTR_RUNQ, 1289 "sched_add: adding td_sched:%p (td:%p) to gbl runq", ts, 1290 td); 1291 cpu = NOCPU; 1292 ts->ts_runq = &runq; 1293 } 1294 1295 if (single_cpu && (cpu != PCPU_GET(cpuid))) { 1296 kick_other_cpu(td->td_priority, cpu); 1297 } else { 1298 if (!single_cpu) { 1299 cpumask_t me = PCPU_GET(cpumask); 1300 cpumask_t idle = idle_cpus_mask & me; 1301 1302 if (!idle && ((flags & SRQ_INTR) == 0) && 1303 (idle_cpus_mask & ~(hlt_cpus_mask | me))) 1304 forwarded = forward_wakeup(cpu); 1305 } 1306 1307 if (!forwarded) { 1308 if ((flags & SRQ_YIELDING) == 0 && maybe_preempt(td)) 1309 return; 1310 else 1311 maybe_resched(td); 1312 } 1313 } 1314 1315 if ((td->td_flags & TDF_NOLOAD) == 0) 1316 sched_load_add(); 1317 runq_add(ts->ts_runq, td, flags); 1318 if (cpu != NOCPU) 1319 runq_length[cpu]++; 1320 } 1321 #else /* SMP */ 1322 { 1323 struct td_sched *ts; 1324 1325 ts = td->td_sched; 1326 THREAD_LOCK_ASSERT(td, MA_OWNED); 1327 KASSERT((td->td_inhibitors == 0), 1328 ("sched_add: trying to run inhibited thread")); 1329 KASSERT((TD_CAN_RUN(td) || TD_IS_RUNNING(td)), 1330 ("sched_add: bad thread state")); 1331 KASSERT(td->td_flags & TDF_INMEM, 1332 ("sched_add: thread swapped out")); 1333 KTR_STATE2(KTR_SCHED, "thread", sched_tdname(td), "runq add", 1334 "prio:%d", td->td_priority, KTR_ATTR_LINKED, 1335 sched_tdname(curthread)); 1336 KTR_POINT1(KTR_SCHED, "thread", sched_tdname(curthread), "wokeup", 1337 KTR_ATTR_LINKED, sched_tdname(td)); 1338 1339 /* 1340 * Now that the thread is moving to the run-queue, set the lock 1341 * to the scheduler's lock. 1342 */ 1343 if (td->td_lock != &sched_lock) { 1344 mtx_lock_spin(&sched_lock); 1345 thread_lock_set(td, &sched_lock); 1346 } 1347 TD_SET_RUNQ(td); 1348 CTR2(KTR_RUNQ, "sched_add: adding td_sched:%p (td:%p) to runq", ts, td); 1349 ts->ts_runq = &runq; 1350 1351 /* 1352 * If we are yielding (on the way out anyhow) or the thread 1353 * being saved is US, then don't try be smart about preemption 1354 * or kicking off another CPU as it won't help and may hinder. 1355 * In the YIEDLING case, we are about to run whoever is being 1356 * put in the queue anyhow, and in the OURSELF case, we are 1357 * puting ourself on the run queue which also only happens 1358 * when we are about to yield. 1359 */ 1360 if ((flags & SRQ_YIELDING) == 0) { 1361 if (maybe_preempt(td)) 1362 return; 1363 } 1364 if ((td->td_flags & TDF_NOLOAD) == 0) 1365 sched_load_add(); 1366 runq_add(ts->ts_runq, td, flags); 1367 maybe_resched(td); 1368 } 1369 #endif /* SMP */ 1370 1371 void 1372 sched_rem(struct thread *td) 1373 { 1374 struct td_sched *ts; 1375 1376 ts = td->td_sched; 1377 KASSERT(td->td_flags & TDF_INMEM, 1378 ("sched_rem: thread swapped out")); 1379 KASSERT(TD_ON_RUNQ(td), 1380 ("sched_rem: thread not on run queue")); 1381 mtx_assert(&sched_lock, MA_OWNED); 1382 KTR_STATE2(KTR_SCHED, "thread", sched_tdname(td), "runq rem", 1383 "prio:%d", td->td_priority, KTR_ATTR_LINKED, 1384 sched_tdname(curthread)); 1385 1386 if ((td->td_flags & TDF_NOLOAD) == 0) 1387 sched_load_rem(); 1388 #ifdef SMP 1389 if (ts->ts_runq != &runq) 1390 runq_length[ts->ts_runq - runq_pcpu]--; 1391 #endif 1392 runq_remove(ts->ts_runq, td); 1393 TD_SET_CAN_RUN(td); 1394 } 1395 1396 /* 1397 * Select threads to run. Note that running threads still consume a 1398 * slot. 1399 */ 1400 struct thread * 1401 sched_choose(void) 1402 { 1403 struct thread *td; 1404 struct runq *rq; 1405 1406 mtx_assert(&sched_lock, MA_OWNED); 1407 #ifdef SMP 1408 struct thread *tdcpu; 1409 1410 rq = &runq; 1411 td = runq_choose_fuzz(&runq, runq_fuzz); 1412 tdcpu = runq_choose(&runq_pcpu[PCPU_GET(cpuid)]); 1413 1414 if (td == NULL || 1415 (tdcpu != NULL && 1416 tdcpu->td_priority < td->td_priority)) { 1417 CTR2(KTR_RUNQ, "choosing td %p from pcpu runq %d", tdcpu, 1418 PCPU_GET(cpuid)); 1419 td = tdcpu; 1420 rq = &runq_pcpu[PCPU_GET(cpuid)]; 1421 } else { 1422 CTR1(KTR_RUNQ, "choosing td_sched %p from main runq", td); 1423 } 1424 1425 #else 1426 rq = &runq; 1427 td = runq_choose(&runq); 1428 #endif 1429 1430 if (td) { 1431 #ifdef SMP 1432 if (td == tdcpu) 1433 runq_length[PCPU_GET(cpuid)]--; 1434 #endif 1435 runq_remove(rq, td); 1436 td->td_flags |= TDF_DIDRUN; 1437 1438 KASSERT(td->td_flags & TDF_INMEM, 1439 ("sched_choose: thread swapped out")); 1440 return (td); 1441 } 1442 return (PCPU_GET(idlethread)); 1443 } 1444 1445 void 1446 sched_preempt(struct thread *td) 1447 { 1448 thread_lock(td); 1449 if (td->td_critnest > 1) 1450 td->td_owepreempt = 1; 1451 else 1452 mi_switch(SW_INVOL | SW_PREEMPT | SWT_PREEMPT, NULL); 1453 thread_unlock(td); 1454 } 1455 1456 void 1457 sched_userret(struct thread *td) 1458 { 1459 /* 1460 * XXX we cheat slightly on the locking here to avoid locking in 1461 * the usual case. Setting td_priority here is essentially an 1462 * incomplete workaround for not setting it properly elsewhere. 1463 * Now that some interrupt handlers are threads, not setting it 1464 * properly elsewhere can clobber it in the window between setting 1465 * it here and returning to user mode, so don't waste time setting 1466 * it perfectly here. 1467 */ 1468 KASSERT((td->td_flags & TDF_BORROWING) == 0, 1469 ("thread with borrowed priority returning to userland")); 1470 if (td->td_priority != td->td_user_pri) { 1471 thread_lock(td); 1472 td->td_priority = td->td_user_pri; 1473 td->td_base_pri = td->td_user_pri; 1474 thread_unlock(td); 1475 } 1476 } 1477 1478 void 1479 sched_bind(struct thread *td, int cpu) 1480 { 1481 struct td_sched *ts; 1482 1483 THREAD_LOCK_ASSERT(td, MA_OWNED|MA_NOTRECURSED); 1484 KASSERT(td == curthread, ("sched_bind: can only bind curthread")); 1485 1486 ts = td->td_sched; 1487 1488 td->td_flags |= TDF_BOUND; 1489 #ifdef SMP 1490 ts->ts_runq = &runq_pcpu[cpu]; 1491 if (PCPU_GET(cpuid) == cpu) 1492 return; 1493 1494 mi_switch(SW_VOL, NULL); 1495 #endif 1496 } 1497 1498 void 1499 sched_unbind(struct thread* td) 1500 { 1501 THREAD_LOCK_ASSERT(td, MA_OWNED); 1502 KASSERT(td == curthread, ("sched_unbind: can only bind curthread")); 1503 td->td_flags &= ~TDF_BOUND; 1504 } 1505 1506 int 1507 sched_is_bound(struct thread *td) 1508 { 1509 THREAD_LOCK_ASSERT(td, MA_OWNED); 1510 return (td->td_flags & TDF_BOUND); 1511 } 1512 1513 void 1514 sched_relinquish(struct thread *td) 1515 { 1516 thread_lock(td); 1517 mi_switch(SW_VOL | SWT_RELINQUISH, NULL); 1518 thread_unlock(td); 1519 } 1520 1521 int 1522 sched_load(void) 1523 { 1524 return (sched_tdcnt); 1525 } 1526 1527 int 1528 sched_sizeof_proc(void) 1529 { 1530 return (sizeof(struct proc)); 1531 } 1532 1533 int 1534 sched_sizeof_thread(void) 1535 { 1536 return (sizeof(struct thread) + sizeof(struct td_sched)); 1537 } 1538 1539 fixpt_t 1540 sched_pctcpu(struct thread *td) 1541 { 1542 struct td_sched *ts; 1543 1544 THREAD_LOCK_ASSERT(td, MA_OWNED); 1545 ts = td->td_sched; 1546 return (ts->ts_pctcpu); 1547 } 1548 1549 void 1550 sched_tick(int cnt) 1551 { 1552 } 1553 1554 /* 1555 * The actual idle process. 1556 */ 1557 void 1558 sched_idletd(void *dummy) 1559 { 1560 struct pcpuidlestat *stat; 1561 1562 stat = DPCPU_PTR(idlestat); 1563 for (;;) { 1564 mtx_assert(&Giant, MA_NOTOWNED); 1565 1566 while (sched_runnable() == 0) { 1567 cpu_idle(stat->idlecalls + stat->oldidlecalls > 64); 1568 stat->idlecalls++; 1569 } 1570 1571 mtx_lock_spin(&sched_lock); 1572 mi_switch(SW_VOL | SWT_IDLE, NULL); 1573 mtx_unlock_spin(&sched_lock); 1574 } 1575 } 1576 1577 /* 1578 * A CPU is entering for the first time or a thread is exiting. 1579 */ 1580 void 1581 sched_throw(struct thread *td) 1582 { 1583 /* 1584 * Correct spinlock nesting. The idle thread context that we are 1585 * borrowing was created so that it would start out with a single 1586 * spin lock (sched_lock) held in fork_trampoline(). Since we've 1587 * explicitly acquired locks in this function, the nesting count 1588 * is now 2 rather than 1. Since we are nested, calling 1589 * spinlock_exit() will simply adjust the counts without allowing 1590 * spin lock using code to interrupt us. 1591 */ 1592 if (td == NULL) { 1593 mtx_lock_spin(&sched_lock); 1594 spinlock_exit(); 1595 } else { 1596 lock_profile_release_lock(&sched_lock.lock_object); 1597 MPASS(td->td_lock == &sched_lock); 1598 } 1599 mtx_assert(&sched_lock, MA_OWNED); 1600 KASSERT(curthread->td_md.md_spinlock_count == 1, ("invalid count")); 1601 PCPU_SET(switchtime, cpu_ticks()); 1602 PCPU_SET(switchticks, ticks); 1603 cpu_throw(td, choosethread()); /* doesn't return */ 1604 } 1605 1606 void 1607 sched_fork_exit(struct thread *td) 1608 { 1609 1610 /* 1611 * Finish setting up thread glue so that it begins execution in a 1612 * non-nested critical section with sched_lock held but not recursed. 1613 */ 1614 td->td_oncpu = PCPU_GET(cpuid); 1615 sched_lock.mtx_lock = (uintptr_t)td; 1616 lock_profile_obtain_lock_success(&sched_lock.lock_object, 1617 0, 0, __FILE__, __LINE__); 1618 THREAD_LOCK_ASSERT(td, MA_OWNED | MA_NOTRECURSED); 1619 } 1620 1621 char * 1622 sched_tdname(struct thread *td) 1623 { 1624 #ifdef KTR 1625 struct td_sched *ts; 1626 1627 ts = td->td_sched; 1628 if (ts->ts_name[0] == '\0') 1629 snprintf(ts->ts_name, sizeof(ts->ts_name), 1630 "%s tid %d", td->td_name, td->td_tid); 1631 return (ts->ts_name); 1632 #else 1633 return (td->td_name); 1634 #endif 1635 } 1636 1637 void 1638 sched_affinity(struct thread *td) 1639 { 1640 #ifdef SMP 1641 struct td_sched *ts; 1642 int cpu; 1643 1644 THREAD_LOCK_ASSERT(td, MA_OWNED); 1645 1646 /* 1647 * Set the TSF_AFFINITY flag if there is at least one CPU this 1648 * thread can't run on. 1649 */ 1650 ts = td->td_sched; 1651 ts->ts_flags &= ~TSF_AFFINITY; 1652 CPU_FOREACH(cpu) { 1653 if (!THREAD_CAN_SCHED(td, cpu)) { 1654 ts->ts_flags |= TSF_AFFINITY; 1655 break; 1656 } 1657 } 1658 1659 /* 1660 * If this thread can run on all CPUs, nothing else to do. 1661 */ 1662 if (!(ts->ts_flags & TSF_AFFINITY)) 1663 return; 1664 1665 /* Pinned threads and bound threads should be left alone. */ 1666 if (td->td_pinned != 0 || td->td_flags & TDF_BOUND) 1667 return; 1668 1669 switch (td->td_state) { 1670 case TDS_RUNQ: 1671 /* 1672 * If we are on a per-CPU runqueue that is in the set, 1673 * then nothing needs to be done. 1674 */ 1675 if (ts->ts_runq != &runq && 1676 THREAD_CAN_SCHED(td, ts->ts_runq - runq_pcpu)) 1677 return; 1678 1679 /* Put this thread on a valid per-CPU runqueue. */ 1680 sched_rem(td); 1681 sched_add(td, SRQ_BORING); 1682 break; 1683 case TDS_RUNNING: 1684 /* 1685 * See if our current CPU is in the set. If not, force a 1686 * context switch. 1687 */ 1688 if (THREAD_CAN_SCHED(td, td->td_oncpu)) 1689 return; 1690 1691 td->td_flags |= TDF_NEEDRESCHED; 1692 if (td != curthread) 1693 ipi_cpu(cpu, IPI_AST); 1694 break; 1695 default: 1696 break; 1697 } 1698 #endif 1699 } 1700