Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)
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sys/kern/sched_4bsd.c
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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_kdtrace.h" 40 41 #include <sys/param.h> 42 #include <sys/systm.h> 43 #include <sys/cpuset.h> 44 #include <sys/kernel.h> 45 #include <sys/ktr.h> 46 #include <sys/lock.h> 47 #include <sys/kthread.h> 48 #include <sys/mutex.h> 49 #include <sys/proc.h> 50 #include <sys/resourcevar.h> 51 #include <sys/sched.h> 52 #include <sys/smp.h> 53 #include <sys/sysctl.h> 54 #include <sys/sx.h> 55 #include <sys/turnstile.h> 56 #include <sys/umtx.h> 57 #include <machine/pcb.h> 58 #include <machine/smp.h> 59 60 #ifdef HWPMC_HOOKS 61 #include <sys/pmckern.h> 62 #endif 63 64 #ifdef KDTRACE_HOOKS 65 #include <sys/dtrace_bsd.h> 66 int dtrace_vtime_active; 67 dtrace_vtime_switch_func_t dtrace_vtime_switch_func; 68 #endif 69 70 /* 71 * INVERSE_ESTCPU_WEIGHT is only suitable for statclock() frequencies in 72 * the range 100-256 Hz (approximately). 73 */ 74 #define ESTCPULIM(e) \ 75 min((e), INVERSE_ESTCPU_WEIGHT * (NICE_WEIGHT * (PRIO_MAX - PRIO_MIN) - \ 76 RQ_PPQ) + INVERSE_ESTCPU_WEIGHT - 1) 77 #ifdef SMP 78 #define INVERSE_ESTCPU_WEIGHT (8 * smp_cpus) 79 #else 80 #define INVERSE_ESTCPU_WEIGHT 8 /* 1 / (priorities per estcpu level). */ 81 #endif 82 #define NICE_WEIGHT 1 /* Priorities per nice level. */ 83 84 /* 85 * The schedulable entity that runs a context. 86 * This is an extension to the thread structure and is tailored to 87 * the requirements of this scheduler 88 */ 89 struct td_sched { 90 TAILQ_ENTRY(td_sched) ts_procq; /* (j/z) Run queue. */ 91 struct thread *ts_thread; /* (*) Active associated thread. */ 92 fixpt_t ts_pctcpu; /* (j) %cpu during p_swtime. */ 93 u_char ts_rqindex; /* (j) Run queue index. */ 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 }; 99 100 /* flags kept in td_flags */ 101 #define TDF_DIDRUN TDF_SCHED0 /* thread actually ran. */ 102 #define TDF_BOUND TDF_SCHED1 /* Bound to one CPU. */ 103 104 /* flags kept in ts_flags */ 105 #define TSF_AFFINITY 0x0001 /* Has a non-"full" CPU set. */ 106 107 #define SKE_RUNQ_PCPU(ts) \ 108 ((ts)->ts_runq != 0 && (ts)->ts_runq != &runq) 109 110 #define THREAD_CAN_SCHED(td, cpu) \ 111 CPU_ISSET((cpu), &(td)->td_cpuset->cs_mask) 112 113 static struct td_sched td_sched0; 114 struct mtx sched_lock; 115 116 static int sched_tdcnt; /* Total runnable threads in the system. */ 117 static int sched_quantum; /* Roundrobin scheduling quantum in ticks. */ 118 #define SCHED_QUANTUM (hz / 10) /* Default sched quantum */ 119 120 static void setup_runqs(void); 121 static void schedcpu(void); 122 static void schedcpu_thread(void); 123 static void sched_priority(struct thread *td, u_char prio); 124 static void sched_setup(void *dummy); 125 static void maybe_resched(struct thread *td); 126 static void updatepri(struct thread *td); 127 static void resetpriority(struct thread *td); 128 static void resetpriority_thread(struct thread *td); 129 #ifdef SMP 130 static int sched_pickcpu(struct thread *td); 131 static int forward_wakeup(int cpunum); 132 static void kick_other_cpu(int pri, int cpuid); 133 #endif 134 135 static struct kproc_desc sched_kp = { 136 "schedcpu", 137 schedcpu_thread, 138 NULL 139 }; 140 SYSINIT(schedcpu, SI_SUB_RUN_SCHEDULER, SI_ORDER_FIRST, kproc_start, 141 &sched_kp); 142 SYSINIT(sched_setup, SI_SUB_RUN_QUEUE, SI_ORDER_FIRST, sched_setup, NULL); 143 144 /* 145 * Global run queue. 146 */ 147 static struct runq runq; 148 149 #ifdef SMP 150 /* 151 * Per-CPU run queues 152 */ 153 static struct runq runq_pcpu[MAXCPU]; 154 long runq_length[MAXCPU]; 155 #endif 156 157 static void 158 setup_runqs(void) 159 { 160 #ifdef SMP 161 int i; 162 163 for (i = 0; i < MAXCPU; ++i) 164 runq_init(&runq_pcpu[i]); 165 #endif 166 167 runq_init(&runq); 168 } 169 170 static int 171 sysctl_kern_quantum(SYSCTL_HANDLER_ARGS) 172 { 173 int error, new_val; 174 175 new_val = sched_quantum * tick; 176 error = sysctl_handle_int(oidp, &new_val, 0, req); 177 if (error != 0 || req->newptr == NULL) 178 return (error); 179 if (new_val < tick) 180 return (EINVAL); 181 sched_quantum = new_val / tick; 182 hogticks = 2 * sched_quantum; 183 return (0); 184 } 185 186 SYSCTL_NODE(_kern, OID_AUTO, sched, CTLFLAG_RD, 0, "Scheduler"); 187 188 SYSCTL_STRING(_kern_sched, OID_AUTO, name, CTLFLAG_RD, "4BSD", 0, 189 "Scheduler name"); 190 191 SYSCTL_PROC(_kern_sched, OID_AUTO, quantum, CTLTYPE_INT | CTLFLAG_RW, 192 0, sizeof sched_quantum, sysctl_kern_quantum, "I", 193 "Roundrobin scheduling quantum in microseconds"); 194 195 #ifdef SMP 196 /* Enable forwarding of wakeups to all other cpus */ 197 SYSCTL_NODE(_kern_sched, OID_AUTO, ipiwakeup, CTLFLAG_RD, NULL, "Kernel SMP"); 198 199 static int forward_wakeup_enabled = 1; 200 SYSCTL_INT(_kern_sched_ipiwakeup, OID_AUTO, enabled, CTLFLAG_RW, 201 &forward_wakeup_enabled, 0, 202 "Forwarding of wakeup to idle CPUs"); 203 204 static int forward_wakeups_requested = 0; 205 SYSCTL_INT(_kern_sched_ipiwakeup, OID_AUTO, requested, CTLFLAG_RD, 206 &forward_wakeups_requested, 0, 207 "Requests for Forwarding of wakeup to idle CPUs"); 208 209 static int forward_wakeups_delivered = 0; 210 SYSCTL_INT(_kern_sched_ipiwakeup, OID_AUTO, delivered, CTLFLAG_RD, 211 &forward_wakeups_delivered, 0, 212 "Completed Forwarding of wakeup to idle CPUs"); 213 214 static int forward_wakeup_use_mask = 1; 215 SYSCTL_INT(_kern_sched_ipiwakeup, OID_AUTO, usemask, CTLFLAG_RW, 216 &forward_wakeup_use_mask, 0, 217 "Use the mask of idle cpus"); 218 219 static int forward_wakeup_use_loop = 0; 220 SYSCTL_INT(_kern_sched_ipiwakeup, OID_AUTO, useloop, CTLFLAG_RW, 221 &forward_wakeup_use_loop, 0, 222 "Use a loop to find idle cpus"); 223 224 static int forward_wakeup_use_single = 0; 225 SYSCTL_INT(_kern_sched_ipiwakeup, OID_AUTO, onecpu, CTLFLAG_RW, 226 &forward_wakeup_use_single, 0, 227 "Only signal one idle cpu"); 228 229 static int forward_wakeup_use_htt = 0; 230 SYSCTL_INT(_kern_sched_ipiwakeup, OID_AUTO, htt2, CTLFLAG_RW, 231 &forward_wakeup_use_htt, 0, 232 "account for htt"); 233 234 #endif 235 #if 0 236 static int sched_followon = 0; 237 SYSCTL_INT(_kern_sched, OID_AUTO, followon, CTLFLAG_RW, 238 &sched_followon, 0, 239 "allow threads to share a quantum"); 240 #endif 241 242 static __inline void 243 sched_load_add(void) 244 { 245 sched_tdcnt++; 246 CTR1(KTR_SCHED, "global load: %d", sched_tdcnt); 247 } 248 249 static __inline void 250 sched_load_rem(void) 251 { 252 sched_tdcnt--; 253 CTR1(KTR_SCHED, "global load: %d", sched_tdcnt); 254 } 255 /* 256 * Arrange to reschedule if necessary, taking the priorities and 257 * schedulers into account. 258 */ 259 static void 260 maybe_resched(struct thread *td) 261 { 262 263 THREAD_LOCK_ASSERT(td, MA_OWNED); 264 if (td->td_priority < curthread->td_priority) 265 curthread->td_flags |= TDF_NEEDRESCHED; 266 } 267 268 /* 269 * Constants for digital decay and forget: 270 * 90% of (td_estcpu) usage in 5 * loadav time 271 * 95% of (ts_pctcpu) usage in 60 seconds (load insensitive) 272 * Note that, as ps(1) mentions, this can let percentages 273 * total over 100% (I've seen 137.9% for 3 processes). 274 * 275 * Note that schedclock() updates td_estcpu and p_cpticks asynchronously. 276 * 277 * We wish to decay away 90% of td_estcpu in (5 * loadavg) seconds. 278 * That is, the system wants to compute a value of decay such 279 * that the following for loop: 280 * for (i = 0; i < (5 * loadavg); i++) 281 * td_estcpu *= decay; 282 * will compute 283 * td_estcpu *= 0.1; 284 * for all values of loadavg: 285 * 286 * Mathematically this loop can be expressed by saying: 287 * decay ** (5 * loadavg) ~= .1 288 * 289 * The system computes decay as: 290 * decay = (2 * loadavg) / (2 * loadavg + 1) 291 * 292 * We wish to prove that the system's computation of decay 293 * will always fulfill the equation: 294 * decay ** (5 * loadavg) ~= .1 295 * 296 * If we compute b as: 297 * b = 2 * loadavg 298 * then 299 * decay = b / (b + 1) 300 * 301 * We now need to prove two things: 302 * 1) Given factor ** (5 * loadavg) ~= .1, prove factor == b/(b+1) 303 * 2) Given b/(b+1) ** power ~= .1, prove power == (5 * loadavg) 304 * 305 * Facts: 306 * For x close to zero, exp(x) =~ 1 + x, since 307 * exp(x) = 0! + x**1/1! + x**2/2! + ... . 308 * therefore exp(-1/b) =~ 1 - (1/b) = (b-1)/b. 309 * For x close to zero, ln(1+x) =~ x, since 310 * ln(1+x) = x - x**2/2 + x**3/3 - ... -1 < x < 1 311 * therefore ln(b/(b+1)) = ln(1 - 1/(b+1)) =~ -1/(b+1). 312 * ln(.1) =~ -2.30 313 * 314 * Proof of (1): 315 * Solve (factor)**(power) =~ .1 given power (5*loadav): 316 * solving for factor, 317 * ln(factor) =~ (-2.30/5*loadav), or 318 * factor =~ exp(-1/((5/2.30)*loadav)) =~ exp(-1/(2*loadav)) = 319 * exp(-1/b) =~ (b-1)/b =~ b/(b+1). QED 320 * 321 * Proof of (2): 322 * Solve (factor)**(power) =~ .1 given factor == (b/(b+1)): 323 * solving for power, 324 * power*ln(b/(b+1)) =~ -2.30, or 325 * power =~ 2.3 * (b + 1) = 4.6*loadav + 2.3 =~ 5*loadav. QED 326 * 327 * Actual power values for the implemented algorithm are as follows: 328 * loadav: 1 2 3 4 329 * power: 5.68 10.32 14.94 19.55 330 */ 331 332 /* calculations for digital decay to forget 90% of usage in 5*loadav sec */ 333 #define loadfactor(loadav) (2 * (loadav)) 334 #define decay_cpu(loadfac, cpu) (((loadfac) * (cpu)) / ((loadfac) + FSCALE)) 335 336 /* decay 95% of `ts_pctcpu' in 60 seconds; see CCPU_SHIFT before changing */ 337 static fixpt_t ccpu = 0.95122942450071400909 * FSCALE; /* exp(-1/20) */ 338 SYSCTL_INT(_kern, OID_AUTO, ccpu, CTLFLAG_RD, &ccpu, 0, ""); 339 340 /* 341 * If `ccpu' is not equal to `exp(-1/20)' and you still want to use the 342 * faster/more-accurate formula, you'll have to estimate CCPU_SHIFT below 343 * and possibly adjust FSHIFT in "param.h" so that (FSHIFT >= CCPU_SHIFT). 344 * 345 * To estimate CCPU_SHIFT for exp(-1/20), the following formula was used: 346 * 1 - exp(-1/20) ~= 0.0487 ~= 0.0488 == 1 (fixed pt, *11* bits). 347 * 348 * If you don't want to bother with the faster/more-accurate formula, you 349 * can set CCPU_SHIFT to (FSHIFT + 1) which will use a slower/less-accurate 350 * (more general) method of calculating the %age of CPU used by a process. 351 */ 352 #define CCPU_SHIFT 11 353 354 /* 355 * Recompute process priorities, every hz ticks. 356 * MP-safe, called without the Giant mutex. 357 */ 358 /* ARGSUSED */ 359 static void 360 schedcpu(void) 361 { 362 register fixpt_t loadfac = loadfactor(averunnable.ldavg[0]); 363 struct thread *td; 364 struct proc *p; 365 struct td_sched *ts; 366 int awake, realstathz; 367 368 realstathz = stathz ? stathz : hz; 369 sx_slock(&allproc_lock); 370 FOREACH_PROC_IN_SYSTEM(p) { 371 PROC_SLOCK(p); 372 FOREACH_THREAD_IN_PROC(p, td) { 373 awake = 0; 374 thread_lock(td); 375 ts = td->td_sched; 376 /* 377 * Increment sleep time (if sleeping). We 378 * ignore overflow, as above. 379 */ 380 /* 381 * The td_sched slptimes are not touched in wakeup 382 * because the thread may not HAVE everything in 383 * memory? XXX I think this is out of date. 384 */ 385 if (TD_ON_RUNQ(td)) { 386 awake = 1; 387 td->td_flags &= ~TDF_DIDRUN; 388 } else if (TD_IS_RUNNING(td)) { 389 awake = 1; 390 /* Do not clear TDF_DIDRUN */ 391 } else if (td->td_flags & TDF_DIDRUN) { 392 awake = 1; 393 td->td_flags &= ~TDF_DIDRUN; 394 } 395 396 /* 397 * ts_pctcpu is only for ps and ttyinfo(). 398 * Do it per td_sched, and add them up at the end? 399 * XXXKSE 400 */ 401 ts->ts_pctcpu = (ts->ts_pctcpu * ccpu) >> FSHIFT; 402 /* 403 * If the td_sched has been idle the entire second, 404 * stop recalculating its priority until 405 * it wakes up. 406 */ 407 if (ts->ts_cpticks != 0) { 408 #if (FSHIFT >= CCPU_SHIFT) 409 ts->ts_pctcpu += (realstathz == 100) 410 ? ((fixpt_t) ts->ts_cpticks) << 411 (FSHIFT - CCPU_SHIFT) : 412 100 * (((fixpt_t) ts->ts_cpticks) 413 << (FSHIFT - CCPU_SHIFT)) / realstathz; 414 #else 415 ts->ts_pctcpu += ((FSCALE - ccpu) * 416 (ts->ts_cpticks * 417 FSCALE / realstathz)) >> FSHIFT; 418 #endif 419 ts->ts_cpticks = 0; 420 } 421 /* 422 * If there are ANY running threads in this process, 423 * then don't count it as sleeping. 424 * XXX: this is broken. 425 */ 426 if (awake) { 427 if (ts->ts_slptime > 1) { 428 /* 429 * In an ideal world, this should not 430 * happen, because whoever woke us 431 * up from the long sleep should have 432 * unwound the slptime and reset our 433 * priority before we run at the stale 434 * priority. Should KASSERT at some 435 * point when all the cases are fixed. 436 */ 437 updatepri(td); 438 } 439 ts->ts_slptime = 0; 440 } else 441 ts->ts_slptime++; 442 if (ts->ts_slptime > 1) { 443 thread_unlock(td); 444 continue; 445 } 446 td->td_estcpu = decay_cpu(loadfac, td->td_estcpu); 447 resetpriority(td); 448 resetpriority_thread(td); 449 thread_unlock(td); 450 } 451 PROC_SUNLOCK(p); 452 } 453 sx_sunlock(&allproc_lock); 454 } 455 456 /* 457 * Main loop for a kthread that executes schedcpu once a second. 458 */ 459 static void 460 schedcpu_thread(void) 461 { 462 463 for (;;) { 464 schedcpu(); 465 pause("-", hz); 466 } 467 } 468 469 /* 470 * Recalculate the priority of a process after it has slept for a while. 471 * For all load averages >= 1 and max td_estcpu of 255, sleeping for at 472 * least six times the loadfactor will decay td_estcpu to zero. 473 */ 474 static void 475 updatepri(struct thread *td) 476 { 477 struct td_sched *ts; 478 fixpt_t loadfac; 479 unsigned int newcpu; 480 481 ts = td->td_sched; 482 loadfac = loadfactor(averunnable.ldavg[0]); 483 if (ts->ts_slptime > 5 * loadfac) 484 td->td_estcpu = 0; 485 else { 486 newcpu = td->td_estcpu; 487 ts->ts_slptime--; /* was incremented in schedcpu() */ 488 while (newcpu && --ts->ts_slptime) 489 newcpu = decay_cpu(loadfac, newcpu); 490 td->td_estcpu = newcpu; 491 } 492 } 493 494 /* 495 * Compute the priority of a process when running in user mode. 496 * Arrange to reschedule if the resulting priority is better 497 * than that of the current process. 498 */ 499 static void 500 resetpriority(struct thread *td) 501 { 502 register unsigned int newpriority; 503 504 if (td->td_pri_class == PRI_TIMESHARE) { 505 newpriority = PUSER + td->td_estcpu / INVERSE_ESTCPU_WEIGHT + 506 NICE_WEIGHT * (td->td_proc->p_nice - PRIO_MIN); 507 newpriority = min(max(newpriority, PRI_MIN_TIMESHARE), 508 PRI_MAX_TIMESHARE); 509 sched_user_prio(td, newpriority); 510 } 511 } 512 513 /* 514 * Update the thread's priority when the associated process's user 515 * priority changes. 516 */ 517 static void 518 resetpriority_thread(struct thread *td) 519 { 520 521 /* Only change threads with a time sharing user priority. */ 522 if (td->td_priority < PRI_MIN_TIMESHARE || 523 td->td_priority > PRI_MAX_TIMESHARE) 524 return; 525 526 /* XXX the whole needresched thing is broken, but not silly. */ 527 maybe_resched(td); 528 529 sched_prio(td, td->td_user_pri); 530 } 531 532 /* ARGSUSED */ 533 static void 534 sched_setup(void *dummy) 535 { 536 setup_runqs(); 537 538 if (sched_quantum == 0) 539 sched_quantum = SCHED_QUANTUM; 540 hogticks = 2 * sched_quantum; 541 542 /* Account for thread0. */ 543 sched_load_add(); 544 } 545 546 /* External interfaces start here */ 547 548 /* 549 * Very early in the boot some setup of scheduler-specific 550 * parts of proc0 and of some scheduler resources needs to be done. 551 * Called from: 552 * proc0_init() 553 */ 554 void 555 schedinit(void) 556 { 557 /* 558 * Set up the scheduler specific parts of proc0. 559 */ 560 proc0.p_sched = NULL; /* XXX */ 561 thread0.td_sched = &td_sched0; 562 thread0.td_lock = &sched_lock; 563 td_sched0.ts_thread = &thread0; 564 mtx_init(&sched_lock, "sched lock", NULL, MTX_SPIN | MTX_RECURSE); 565 } 566 567 int 568 sched_runnable(void) 569 { 570 #ifdef SMP 571 return runq_check(&runq) + runq_check(&runq_pcpu[PCPU_GET(cpuid)]); 572 #else 573 return runq_check(&runq); 574 #endif 575 } 576 577 int 578 sched_rr_interval(void) 579 { 580 if (sched_quantum == 0) 581 sched_quantum = SCHED_QUANTUM; 582 return (sched_quantum); 583 } 584 585 /* 586 * We adjust the priority of the current process. The priority of 587 * a process gets worse as it accumulates CPU time. The cpu usage 588 * estimator (td_estcpu) is increased here. resetpriority() will 589 * compute a different priority each time td_estcpu increases by 590 * INVERSE_ESTCPU_WEIGHT 591 * (until MAXPRI is reached). The cpu usage estimator ramps up 592 * quite quickly when the process is running (linearly), and decays 593 * away exponentially, at a rate which is proportionally slower when 594 * the system is busy. The basic principle is that the system will 595 * 90% forget that the process used a lot of CPU time in 5 * loadav 596 * seconds. This causes the system to favor processes which haven't 597 * run much recently, and to round-robin among other processes. 598 */ 599 void 600 sched_clock(struct thread *td) 601 { 602 struct td_sched *ts; 603 604 THREAD_LOCK_ASSERT(td, MA_OWNED); 605 ts = td->td_sched; 606 607 ts->ts_cpticks++; 608 td->td_estcpu = ESTCPULIM(td->td_estcpu + 1); 609 if ((td->td_estcpu % INVERSE_ESTCPU_WEIGHT) == 0) { 610 resetpriority(td); 611 resetpriority_thread(td); 612 } 613 614 /* 615 * Force a context switch if the current thread has used up a full 616 * quantum (default quantum is 100ms). 617 */ 618 if (!TD_IS_IDLETHREAD(td) && 619 ticks - PCPU_GET(switchticks) >= sched_quantum) 620 td->td_flags |= TDF_NEEDRESCHED; 621 } 622 623 /* 624 * Charge child's scheduling CPU usage to parent. 625 */ 626 void 627 sched_exit(struct proc *p, struct thread *td) 628 { 629 630 CTR3(KTR_SCHED, "sched_exit: %p(%s) prio %d", 631 td, td->td_proc->p_comm, td->td_priority); 632 PROC_SLOCK_ASSERT(p, MA_OWNED); 633 sched_exit_thread(FIRST_THREAD_IN_PROC(p), td); 634 } 635 636 void 637 sched_exit_thread(struct thread *td, struct thread *child) 638 { 639 640 CTR3(KTR_SCHED, "sched_exit_thread: %p(%s) prio %d", 641 child, child->td_proc->p_comm, child->td_priority); 642 thread_lock(td); 643 td->td_estcpu = ESTCPULIM(td->td_estcpu + child->td_estcpu); 644 thread_unlock(td); 645 mtx_lock_spin(&sched_lock); 646 if ((child->td_proc->p_flag & P_NOLOAD) == 0) 647 sched_load_rem(); 648 mtx_unlock_spin(&sched_lock); 649 } 650 651 void 652 sched_fork(struct thread *td, struct thread *childtd) 653 { 654 sched_fork_thread(td, childtd); 655 } 656 657 void 658 sched_fork_thread(struct thread *td, struct thread *childtd) 659 { 660 childtd->td_estcpu = td->td_estcpu; 661 childtd->td_lock = &sched_lock; 662 childtd->td_cpuset = cpuset_ref(td->td_cpuset); 663 childtd->td_priority = childtd->td_base_pri; 664 sched_newthread(childtd); 665 childtd->td_sched->ts_flags |= (td->td_sched->ts_flags & TSF_AFFINITY); 666 } 667 668 void 669 sched_nice(struct proc *p, int nice) 670 { 671 struct thread *td; 672 673 PROC_LOCK_ASSERT(p, MA_OWNED); 674 PROC_SLOCK_ASSERT(p, MA_OWNED); 675 p->p_nice = nice; 676 FOREACH_THREAD_IN_PROC(p, td) { 677 thread_lock(td); 678 resetpriority(td); 679 resetpriority_thread(td); 680 thread_unlock(td); 681 } 682 } 683 684 void 685 sched_class(struct thread *td, int class) 686 { 687 THREAD_LOCK_ASSERT(td, MA_OWNED); 688 td->td_pri_class = class; 689 } 690 691 /* 692 * Adjust the priority of a thread. 693 */ 694 static void 695 sched_priority(struct thread *td, u_char prio) 696 { 697 CTR6(KTR_SCHED, "sched_prio: %p(%s) prio %d newprio %d by %p(%s)", 698 td, td->td_proc->p_comm, td->td_priority, prio, curthread, 699 curthread->td_proc->p_comm); 700 701 THREAD_LOCK_ASSERT(td, MA_OWNED); 702 if (td->td_priority == prio) 703 return; 704 td->td_priority = prio; 705 if (TD_ON_RUNQ(td) && 706 td->td_sched->ts_rqindex != (prio / RQ_PPQ)) { 707 sched_rem(td); 708 sched_add(td, SRQ_BORING); 709 } 710 } 711 712 /* 713 * Update a thread's priority when it is lent another thread's 714 * priority. 715 */ 716 void 717 sched_lend_prio(struct thread *td, u_char prio) 718 { 719 720 td->td_flags |= TDF_BORROWING; 721 sched_priority(td, prio); 722 } 723 724 /* 725 * Restore a thread's priority when priority propagation is 726 * over. The prio argument is the minimum priority the thread 727 * needs to have to satisfy other possible priority lending 728 * requests. If the thread's regulary priority is less 729 * important than prio the thread will keep a priority boost 730 * of prio. 731 */ 732 void 733 sched_unlend_prio(struct thread *td, u_char prio) 734 { 735 u_char base_pri; 736 737 if (td->td_base_pri >= PRI_MIN_TIMESHARE && 738 td->td_base_pri <= PRI_MAX_TIMESHARE) 739 base_pri = td->td_user_pri; 740 else 741 base_pri = td->td_base_pri; 742 if (prio >= base_pri) { 743 td->td_flags &= ~TDF_BORROWING; 744 sched_prio(td, base_pri); 745 } else 746 sched_lend_prio(td, prio); 747 } 748 749 void 750 sched_prio(struct thread *td, u_char prio) 751 { 752 u_char oldprio; 753 754 /* First, update the base priority. */ 755 td->td_base_pri = prio; 756 757 /* 758 * If the thread is borrowing another thread's priority, don't ever 759 * lower the priority. 760 */ 761 if (td->td_flags & TDF_BORROWING && td->td_priority < prio) 762 return; 763 764 /* Change the real priority. */ 765 oldprio = td->td_priority; 766 sched_priority(td, prio); 767 768 /* 769 * If the thread is on a turnstile, then let the turnstile update 770 * its state. 771 */ 772 if (TD_ON_LOCK(td) && oldprio != prio) 773 turnstile_adjust(td, oldprio); 774 } 775 776 void 777 sched_user_prio(struct thread *td, u_char prio) 778 { 779 u_char oldprio; 780 781 THREAD_LOCK_ASSERT(td, MA_OWNED); 782 td->td_base_user_pri = prio; 783 if (td->td_flags & TDF_UBORROWING && td->td_user_pri <= prio) 784 return; 785 oldprio = td->td_user_pri; 786 td->td_user_pri = prio; 787 } 788 789 void 790 sched_lend_user_prio(struct thread *td, u_char prio) 791 { 792 u_char oldprio; 793 794 THREAD_LOCK_ASSERT(td, MA_OWNED); 795 td->td_flags |= TDF_UBORROWING; 796 797 oldprio = td->td_user_pri; 798 td->td_user_pri = prio; 799 } 800 801 void 802 sched_unlend_user_prio(struct thread *td, u_char prio) 803 { 804 u_char base_pri; 805 806 THREAD_LOCK_ASSERT(td, MA_OWNED); 807 base_pri = td->td_base_user_pri; 808 if (prio >= base_pri) { 809 td->td_flags &= ~TDF_UBORROWING; 810 sched_user_prio(td, base_pri); 811 } else { 812 sched_lend_user_prio(td, prio); 813 } 814 } 815 816 void 817 sched_sleep(struct thread *td) 818 { 819 820 THREAD_LOCK_ASSERT(td, MA_OWNED); 821 td->td_slptick = ticks; 822 td->td_sched->ts_slptime = 0; 823 } 824 825 void 826 sched_switch(struct thread *td, struct thread *newtd, int flags) 827 { 828 struct mtx *tmtx; 829 struct td_sched *ts; 830 struct proc *p; 831 832 tmtx = NULL; 833 ts = td->td_sched; 834 p = td->td_proc; 835 836 THREAD_LOCK_ASSERT(td, MA_OWNED); 837 838 /* 839 * Switch to the sched lock to fix things up and pick 840 * a new thread. 841 * Block the td_lock in order to avoid breaking the critical path. 842 */ 843 if (td->td_lock != &sched_lock) { 844 mtx_lock_spin(&sched_lock); 845 tmtx = thread_lock_block(td); 846 } 847 848 if ((p->p_flag & P_NOLOAD) == 0) 849 sched_load_rem(); 850 851 td->td_lastcpu = td->td_oncpu; 852 if (!(flags & SW_PREEMPT)) 853 td->td_flags &= ~TDF_NEEDRESCHED; 854 td->td_owepreempt = 0; 855 td->td_oncpu = NOCPU; 856 857 /* 858 * At the last moment, if this thread is still marked RUNNING, 859 * then put it back on the run queue as it has not been suspended 860 * or stopped or any thing else similar. We never put the idle 861 * threads on the run queue, however. 862 */ 863 if (td->td_flags & TDF_IDLETD) { 864 TD_SET_CAN_RUN(td); 865 #ifdef SMP 866 idle_cpus_mask &= ~PCPU_GET(cpumask); 867 #endif 868 } else { 869 if (TD_IS_RUNNING(td)) { 870 /* Put us back on the run queue. */ 871 sched_add(td, (flags & SW_PREEMPT) ? 872 SRQ_OURSELF|SRQ_YIELDING|SRQ_PREEMPTED : 873 SRQ_OURSELF|SRQ_YIELDING); 874 } 875 } 876 if (newtd) { 877 /* 878 * The thread we are about to run needs to be counted 879 * as if it had been added to the run queue and selected. 880 * It came from: 881 * * A preemption 882 * * An upcall 883 * * A followon 884 */ 885 KASSERT((newtd->td_inhibitors == 0), 886 ("trying to run inhibited thread")); 887 newtd->td_flags |= TDF_DIDRUN; 888 TD_SET_RUNNING(newtd); 889 if ((newtd->td_proc->p_flag & P_NOLOAD) == 0) 890 sched_load_add(); 891 } else { 892 newtd = choosethread(); 893 MPASS(newtd->td_lock == &sched_lock); 894 } 895 896 if (td != newtd) { 897 #ifdef HWPMC_HOOKS 898 if (PMC_PROC_IS_USING_PMCS(td->td_proc)) 899 PMC_SWITCH_CONTEXT(td, PMC_FN_CSW_OUT); 900 #endif 901 902 #ifdef KDTRACE_HOOKS 903 /* 904 * If DTrace has set the active vtime enum to anything 905 * other than INACTIVE (0), then it should have set the 906 * function to call. 907 */ 908 if (dtrace_vtime_active) 909 (*dtrace_vtime_switch_func)(newtd); 910 #endif 911 /* I feel sleepy */ 912 cpu_switch(td, newtd, tmtx != NULL ? tmtx : td->td_lock); 913 /* 914 * Where am I? What year is it? 915 * We are in the same thread that went to sleep above, 916 * but any amount of time may have passed. All our context 917 * will still be available as will local variables. 918 * PCPU values however may have changed as we may have 919 * changed CPU so don't trust cached values of them. 920 * New threads will go to fork_exit() instead of here 921 * so if you change things here you may need to change 922 * things there too. 923 * 924 * If the thread above was exiting it will never wake 925 * up again here, so either it has saved everything it 926 * needed to, or the thread_wait() or wait() will 927 * need to reap it. 928 */ 929 #ifdef HWPMC_HOOKS 930 if (PMC_PROC_IS_USING_PMCS(td->td_proc)) 931 PMC_SWITCH_CONTEXT(td, PMC_FN_CSW_IN); 932 #endif 933 } 934 935 #ifdef SMP 936 if (td->td_flags & TDF_IDLETD) 937 idle_cpus_mask |= PCPU_GET(cpumask); 938 #endif 939 sched_lock.mtx_lock = (uintptr_t)td; 940 td->td_oncpu = PCPU_GET(cpuid); 941 MPASS(td->td_lock == &sched_lock); 942 } 943 944 void 945 sched_wakeup(struct thread *td) 946 { 947 struct td_sched *ts; 948 949 THREAD_LOCK_ASSERT(td, MA_OWNED); 950 ts = td->td_sched; 951 if (ts->ts_slptime > 1) { 952 updatepri(td); 953 resetpriority(td); 954 } 955 td->td_slptick = ticks; 956 ts->ts_slptime = 0; 957 sched_add(td, SRQ_BORING); 958 } 959 960 #ifdef SMP 961 static int 962 forward_wakeup(int cpunum) 963 { 964 struct pcpu *pc; 965 cpumask_t dontuse, id, map, map2, map3, me; 966 967 mtx_assert(&sched_lock, MA_OWNED); 968 969 CTR0(KTR_RUNQ, "forward_wakeup()"); 970 971 if ((!forward_wakeup_enabled) || 972 (forward_wakeup_use_mask == 0 && forward_wakeup_use_loop == 0)) 973 return (0); 974 if (!smp_started || cold || panicstr) 975 return (0); 976 977 forward_wakeups_requested++; 978 979 /* 980 * Check the idle mask we received against what we calculated 981 * before in the old version. 982 */ 983 me = PCPU_GET(cpumask); 984 985 /* Don't bother if we should be doing it ourself. */ 986 if ((me & idle_cpus_mask) && (cpunum == NOCPU || me == (1 << cpunum))) 987 return (0); 988 989 dontuse = me | stopped_cpus | hlt_cpus_mask; 990 map3 = 0; 991 if (forward_wakeup_use_loop) { 992 SLIST_FOREACH(pc, &cpuhead, pc_allcpu) { 993 id = pc->pc_cpumask; 994 if ((id & dontuse) == 0 && 995 pc->pc_curthread == pc->pc_idlethread) { 996 map3 |= id; 997 } 998 } 999 } 1000 1001 if (forward_wakeup_use_mask) { 1002 map = 0; 1003 map = idle_cpus_mask & ~dontuse; 1004 1005 /* If they are both on, compare and use loop if different. */ 1006 if (forward_wakeup_use_loop) { 1007 if (map != map3) { 1008 printf("map (%02X) != map3 (%02X)\n", map, 1009 map3); 1010 map = map3; 1011 } 1012 } 1013 } else { 1014 map = map3; 1015 } 1016 1017 /* If we only allow a specific CPU, then mask off all the others. */ 1018 if (cpunum != NOCPU) { 1019 KASSERT((cpunum <= mp_maxcpus),("forward_wakeup: bad cpunum.")); 1020 map &= (1 << cpunum); 1021 } else { 1022 /* Try choose an idle die. */ 1023 if (forward_wakeup_use_htt) { 1024 map2 = (map & (map >> 1)) & 0x5555; 1025 if (map2) { 1026 map = map2; 1027 } 1028 } 1029 1030 /* Set only one bit. */ 1031 if (forward_wakeup_use_single) { 1032 map = map & ((~map) + 1); 1033 } 1034 } 1035 if (map) { 1036 forward_wakeups_delivered++; 1037 ipi_selected(map, IPI_AST); 1038 return (1); 1039 } 1040 if (cpunum == NOCPU) 1041 printf("forward_wakeup: Idle processor not found\n"); 1042 return (0); 1043 } 1044 1045 static void 1046 kick_other_cpu(int pri, int cpuid) 1047 { 1048 struct pcpu *pcpu; 1049 int cpri; 1050 1051 pcpu = pcpu_find(cpuid); 1052 if (idle_cpus_mask & pcpu->pc_cpumask) { 1053 forward_wakeups_delivered++; 1054 ipi_selected(pcpu->pc_cpumask, IPI_AST); 1055 return; 1056 } 1057 1058 cpri = pcpu->pc_curthread->td_priority; 1059 if (pri >= cpri) 1060 return; 1061 1062 #if defined(IPI_PREEMPTION) && defined(PREEMPTION) 1063 #if !defined(FULL_PREEMPTION) 1064 if (pri <= PRI_MAX_ITHD) 1065 #endif /* ! FULL_PREEMPTION */ 1066 { 1067 ipi_selected(pcpu->pc_cpumask, IPI_PREEMPT); 1068 return; 1069 } 1070 #endif /* defined(IPI_PREEMPTION) && defined(PREEMPTION) */ 1071 1072 pcpu->pc_curthread->td_flags |= TDF_NEEDRESCHED; 1073 ipi_selected(pcpu->pc_cpumask, IPI_AST); 1074 return; 1075 } 1076 #endif /* SMP */ 1077 1078 #ifdef SMP 1079 static int 1080 sched_pickcpu(struct thread *td) 1081 { 1082 int best, cpu; 1083 1084 mtx_assert(&sched_lock, MA_OWNED); 1085 1086 if (THREAD_CAN_SCHED(td, td->td_lastcpu)) 1087 best = td->td_lastcpu; 1088 else 1089 best = NOCPU; 1090 for (cpu = 0; cpu <= mp_maxid; cpu++) { 1091 if (CPU_ABSENT(cpu)) 1092 continue; 1093 if (!THREAD_CAN_SCHED(td, cpu)) 1094 continue; 1095 1096 if (best == NOCPU) 1097 best = cpu; 1098 else if (runq_length[cpu] < runq_length[best]) 1099 best = cpu; 1100 } 1101 KASSERT(best != NOCPU, ("no valid CPUs")); 1102 1103 return (best); 1104 } 1105 #endif 1106 1107 void 1108 sched_add(struct thread *td, int flags) 1109 #ifdef SMP 1110 { 1111 struct td_sched *ts; 1112 int forwarded = 0; 1113 int cpu; 1114 int single_cpu = 0; 1115 1116 ts = td->td_sched; 1117 THREAD_LOCK_ASSERT(td, MA_OWNED); 1118 KASSERT((td->td_inhibitors == 0), 1119 ("sched_add: trying to run inhibited thread")); 1120 KASSERT((TD_CAN_RUN(td) || TD_IS_RUNNING(td)), 1121 ("sched_add: bad thread state")); 1122 KASSERT(td->td_flags & TDF_INMEM, 1123 ("sched_add: thread swapped out")); 1124 CTR5(KTR_SCHED, "sched_add: %p(%s) prio %d by %p(%s)", 1125 td, td->td_proc->p_comm, td->td_priority, curthread, 1126 curthread->td_proc->p_comm); 1127 1128 /* 1129 * Now that the thread is moving to the run-queue, set the lock 1130 * to the scheduler's lock. 1131 */ 1132 if (td->td_lock != &sched_lock) { 1133 mtx_lock_spin(&sched_lock); 1134 thread_lock_set(td, &sched_lock); 1135 } 1136 TD_SET_RUNQ(td); 1137 1138 if (td->td_pinned != 0) { 1139 cpu = td->td_lastcpu; 1140 ts->ts_runq = &runq_pcpu[cpu]; 1141 single_cpu = 1; 1142 CTR3(KTR_RUNQ, 1143 "sched_add: Put td_sched:%p(td:%p) on cpu%d runq", ts, td, 1144 cpu); 1145 } else if (td->td_flags & TDF_BOUND) { 1146 /* Find CPU from bound runq. */ 1147 KASSERT(SKE_RUNQ_PCPU(ts), 1148 ("sched_add: bound td_sched not on cpu runq")); 1149 cpu = ts->ts_runq - &runq_pcpu[0]; 1150 single_cpu = 1; 1151 CTR3(KTR_RUNQ, 1152 "sched_add: Put td_sched:%p(td:%p) on cpu%d runq", ts, td, 1153 cpu); 1154 } else if (ts->ts_flags & TSF_AFFINITY) { 1155 /* Find a valid CPU for our cpuset */ 1156 cpu = sched_pickcpu(td); 1157 ts->ts_runq = &runq_pcpu[cpu]; 1158 single_cpu = 1; 1159 CTR3(KTR_RUNQ, 1160 "sched_add: Put td_sched:%p(td:%p) on cpu%d runq", ts, td, 1161 cpu); 1162 } else { 1163 CTR2(KTR_RUNQ, 1164 "sched_add: adding td_sched:%p (td:%p) to gbl runq", ts, 1165 td); 1166 cpu = NOCPU; 1167 ts->ts_runq = &runq; 1168 } 1169 1170 if (single_cpu && (cpu != PCPU_GET(cpuid))) { 1171 kick_other_cpu(td->td_priority, cpu); 1172 } else { 1173 if (!single_cpu) { 1174 cpumask_t me = PCPU_GET(cpumask); 1175 cpumask_t idle = idle_cpus_mask & me; 1176 1177 if (!idle && ((flags & SRQ_INTR) == 0) && 1178 (idle_cpus_mask & ~(hlt_cpus_mask | me))) 1179 forwarded = forward_wakeup(cpu); 1180 } 1181 1182 if (!forwarded) { 1183 if ((flags & SRQ_YIELDING) == 0 && maybe_preempt(td)) 1184 return; 1185 else 1186 maybe_resched(td); 1187 } 1188 } 1189 1190 if ((td->td_proc->p_flag & P_NOLOAD) == 0) 1191 sched_load_add(); 1192 runq_add(ts->ts_runq, ts, flags); 1193 if (cpu != NOCPU) 1194 runq_length[cpu]++; 1195 } 1196 #else /* SMP */ 1197 { 1198 struct td_sched *ts; 1199 1200 ts = td->td_sched; 1201 THREAD_LOCK_ASSERT(td, MA_OWNED); 1202 KASSERT((td->td_inhibitors == 0), 1203 ("sched_add: trying to run inhibited thread")); 1204 KASSERT((TD_CAN_RUN(td) || TD_IS_RUNNING(td)), 1205 ("sched_add: bad thread state")); 1206 KASSERT(td->td_flags & TDF_INMEM, 1207 ("sched_add: thread swapped out")); 1208 CTR5(KTR_SCHED, "sched_add: %p(%s) prio %d by %p(%s)", 1209 td, td->td_proc->p_comm, td->td_priority, curthread, 1210 curthread->td_proc->p_comm); 1211 1212 /* 1213 * Now that the thread is moving to the run-queue, set the lock 1214 * to the scheduler's lock. 1215 */ 1216 if (td->td_lock != &sched_lock) { 1217 mtx_lock_spin(&sched_lock); 1218 thread_lock_set(td, &sched_lock); 1219 } 1220 TD_SET_RUNQ(td); 1221 CTR2(KTR_RUNQ, "sched_add: adding td_sched:%p (td:%p) to runq", ts, td); 1222 ts->ts_runq = &runq; 1223 1224 /* 1225 * If we are yielding (on the way out anyhow) or the thread 1226 * being saved is US, then don't try be smart about preemption 1227 * or kicking off another CPU as it won't help and may hinder. 1228 * In the YIEDLING case, we are about to run whoever is being 1229 * put in the queue anyhow, and in the OURSELF case, we are 1230 * puting ourself on the run queue which also only happens 1231 * when we are about to yield. 1232 */ 1233 if ((flags & SRQ_YIELDING) == 0) { 1234 if (maybe_preempt(td)) 1235 return; 1236 } 1237 if ((td->td_proc->p_flag & P_NOLOAD) == 0) 1238 sched_load_add(); 1239 runq_add(ts->ts_runq, ts, flags); 1240 maybe_resched(td); 1241 } 1242 #endif /* SMP */ 1243 1244 void 1245 sched_rem(struct thread *td) 1246 { 1247 struct td_sched *ts; 1248 1249 ts = td->td_sched; 1250 KASSERT(td->td_flags & TDF_INMEM, 1251 ("sched_rem: thread swapped out")); 1252 KASSERT(TD_ON_RUNQ(td), 1253 ("sched_rem: thread not on run queue")); 1254 mtx_assert(&sched_lock, MA_OWNED); 1255 CTR5(KTR_SCHED, "sched_rem: %p(%s) prio %d by %p(%s)", 1256 td, td->td_proc->p_comm, td->td_priority, curthread, 1257 curthread->td_proc->p_comm); 1258 1259 if ((td->td_proc->p_flag & P_NOLOAD) == 0) 1260 sched_load_rem(); 1261 #ifdef SMP 1262 if (ts->ts_runq != &runq) 1263 runq_length[ts->ts_runq - runq_pcpu]--; 1264 #endif 1265 runq_remove(ts->ts_runq, ts); 1266 TD_SET_CAN_RUN(td); 1267 } 1268 1269 /* 1270 * Select threads to run. Note that running threads still consume a 1271 * slot. 1272 */ 1273 struct thread * 1274 sched_choose(void) 1275 { 1276 struct td_sched *ts; 1277 struct runq *rq; 1278 1279 mtx_assert(&sched_lock, MA_OWNED); 1280 #ifdef SMP 1281 struct td_sched *kecpu; 1282 1283 rq = &runq; 1284 ts = runq_choose(&runq); 1285 kecpu = runq_choose(&runq_pcpu[PCPU_GET(cpuid)]); 1286 1287 if (ts == NULL || 1288 (kecpu != NULL && 1289 kecpu->ts_thread->td_priority < ts->ts_thread->td_priority)) { 1290 CTR2(KTR_RUNQ, "choosing td_sched %p from pcpu runq %d", kecpu, 1291 PCPU_GET(cpuid)); 1292 ts = kecpu; 1293 rq = &runq_pcpu[PCPU_GET(cpuid)]; 1294 } else { 1295 CTR1(KTR_RUNQ, "choosing td_sched %p from main runq", ts); 1296 } 1297 1298 #else 1299 rq = &runq; 1300 ts = runq_choose(&runq); 1301 #endif 1302 1303 if (ts) { 1304 #ifdef SMP 1305 if (ts == kecpu) 1306 runq_length[PCPU_GET(cpuid)]--; 1307 #endif 1308 runq_remove(rq, ts); 1309 ts->ts_thread->td_flags |= TDF_DIDRUN; 1310 1311 KASSERT(ts->ts_thread->td_flags & TDF_INMEM, 1312 ("sched_choose: thread swapped out")); 1313 return (ts->ts_thread); 1314 } 1315 return (PCPU_GET(idlethread)); 1316 } 1317 1318 void 1319 sched_userret(struct thread *td) 1320 { 1321 /* 1322 * XXX we cheat slightly on the locking here to avoid locking in 1323 * the usual case. Setting td_priority here is essentially an 1324 * incomplete workaround for not setting it properly elsewhere. 1325 * Now that some interrupt handlers are threads, not setting it 1326 * properly elsewhere can clobber it in the window between setting 1327 * it here and returning to user mode, so don't waste time setting 1328 * it perfectly here. 1329 */ 1330 KASSERT((td->td_flags & TDF_BORROWING) == 0, 1331 ("thread with borrowed priority returning to userland")); 1332 if (td->td_priority != td->td_user_pri) { 1333 thread_lock(td); 1334 td->td_priority = td->td_user_pri; 1335 td->td_base_pri = td->td_user_pri; 1336 thread_unlock(td); 1337 } 1338 } 1339 1340 void 1341 sched_bind(struct thread *td, int cpu) 1342 { 1343 struct td_sched *ts; 1344 1345 THREAD_LOCK_ASSERT(td, MA_OWNED|MA_NOTRECURSED); 1346 KASSERT(td == curthread, ("sched_bind: can only bind curthread")); 1347 1348 ts = td->td_sched; 1349 1350 td->td_flags |= TDF_BOUND; 1351 #ifdef SMP 1352 ts->ts_runq = &runq_pcpu[cpu]; 1353 if (PCPU_GET(cpuid) == cpu) 1354 return; 1355 1356 mi_switch(SW_VOL, NULL); 1357 #endif 1358 } 1359 1360 void 1361 sched_unbind(struct thread* td) 1362 { 1363 THREAD_LOCK_ASSERT(td, MA_OWNED); 1364 KASSERT(td == curthread, ("sched_unbind: can only bind curthread")); 1365 td->td_flags &= ~TDF_BOUND; 1366 } 1367 1368 int 1369 sched_is_bound(struct thread *td) 1370 { 1371 THREAD_LOCK_ASSERT(td, MA_OWNED); 1372 return (td->td_flags & TDF_BOUND); 1373 } 1374 1375 void 1376 sched_relinquish(struct thread *td) 1377 { 1378 thread_lock(td); 1379 SCHED_STAT_INC(switch_relinquish); 1380 mi_switch(SW_VOL, NULL); 1381 thread_unlock(td); 1382 } 1383 1384 int 1385 sched_load(void) 1386 { 1387 return (sched_tdcnt); 1388 } 1389 1390 int 1391 sched_sizeof_proc(void) 1392 { 1393 return (sizeof(struct proc)); 1394 } 1395 1396 int 1397 sched_sizeof_thread(void) 1398 { 1399 return (sizeof(struct thread) + sizeof(struct td_sched)); 1400 } 1401 1402 fixpt_t 1403 sched_pctcpu(struct thread *td) 1404 { 1405 struct td_sched *ts; 1406 1407 THREAD_LOCK_ASSERT(td, MA_OWNED); 1408 ts = td->td_sched; 1409 return (ts->ts_pctcpu); 1410 } 1411 1412 void 1413 sched_tick(void) 1414 { 1415 } 1416 1417 /* 1418 * The actual idle process. 1419 */ 1420 void 1421 sched_idletd(void *dummy) 1422 { 1423 struct proc *p; 1424 struct thread *td; 1425 1426 td = curthread; 1427 p = td->td_proc; 1428 for (;;) { 1429 mtx_assert(&Giant, MA_NOTOWNED); 1430 1431 while (sched_runnable() == 0) 1432 cpu_idle(); 1433 1434 mtx_lock_spin(&sched_lock); 1435 mi_switch(SW_VOL, NULL); 1436 mtx_unlock_spin(&sched_lock); 1437 } 1438 } 1439 1440 /* 1441 * A CPU is entering for the first time or a thread is exiting. 1442 */ 1443 void 1444 sched_throw(struct thread *td) 1445 { 1446 /* 1447 * Correct spinlock nesting. The idle thread context that we are 1448 * borrowing was created so that it would start out with a single 1449 * spin lock (sched_lock) held in fork_trampoline(). Since we've 1450 * explicitly acquired locks in this function, the nesting count 1451 * is now 2 rather than 1. Since we are nested, calling 1452 * spinlock_exit() will simply adjust the counts without allowing 1453 * spin lock using code to interrupt us. 1454 */ 1455 if (td == NULL) { 1456 mtx_lock_spin(&sched_lock); 1457 spinlock_exit(); 1458 } else { 1459 MPASS(td->td_lock == &sched_lock); 1460 } 1461 mtx_assert(&sched_lock, MA_OWNED); 1462 KASSERT(curthread->td_md.md_spinlock_count == 1, ("invalid count")); 1463 PCPU_SET(switchtime, cpu_ticks()); 1464 PCPU_SET(switchticks, ticks); 1465 cpu_throw(td, choosethread()); /* doesn't return */ 1466 } 1467 1468 void 1469 sched_fork_exit(struct thread *td) 1470 { 1471 1472 /* 1473 * Finish setting up thread glue so that it begins execution in a 1474 * non-nested critical section with sched_lock held but not recursed. 1475 */ 1476 td->td_oncpu = PCPU_GET(cpuid); 1477 sched_lock.mtx_lock = (uintptr_t)td; 1478 THREAD_LOCK_ASSERT(td, MA_OWNED | MA_NOTRECURSED); 1479 } 1480 1481 void 1482 sched_affinity(struct thread *td) 1483 { 1484 #ifdef SMP 1485 struct td_sched *ts; 1486 int cpu; 1487 1488 THREAD_LOCK_ASSERT(td, MA_OWNED); 1489 1490 /* 1491 * Set the TSF_AFFINITY flag if there is at least one CPU this 1492 * thread can't run on. 1493 */ 1494 ts = td->td_sched; 1495 ts->ts_flags &= ~TSF_AFFINITY; 1496 for (cpu = 0; cpu <= mp_maxid; cpu++) { 1497 if (CPU_ABSENT(cpu)) 1498 continue; 1499 if (!THREAD_CAN_SCHED(td, cpu)) { 1500 ts->ts_flags |= TSF_AFFINITY; 1501 break; 1502 } 1503 } 1504 1505 /* 1506 * If this thread can run on all CPUs, nothing else to do. 1507 */ 1508 if (!(ts->ts_flags & TSF_AFFINITY)) 1509 return; 1510 1511 /* Pinned threads and bound threads should be left alone. */ 1512 if (td->td_pinned != 0 || td->td_flags & TDF_BOUND) 1513 return; 1514 1515 switch (td->td_state) { 1516 case TDS_RUNQ: 1517 /* 1518 * If we are on a per-CPU runqueue that is in the set, 1519 * then nothing needs to be done. 1520 */ 1521 if (ts->ts_runq != &runq && 1522 THREAD_CAN_SCHED(td, ts->ts_runq - runq_pcpu)) 1523 return; 1524 1525 /* Put this thread on a valid per-CPU runqueue. */ 1526 sched_rem(td); 1527 sched_add(td, SRQ_BORING); 1528 break; 1529 case TDS_RUNNING: 1530 /* 1531 * See if our current CPU is in the set. If not, force a 1532 * context switch. 1533 */ 1534 if (THREAD_CAN_SCHED(td, td->td_oncpu)) 1535 return; 1536 1537 td->td_flags |= TDF_NEEDRESCHED; 1538 if (td != curthread) 1539 ipi_selected(1 << cpu, IPI_AST); 1540 break; 1541 default: 1542 break; 1543 } 1544 #endif 1545 } 1546 1547 #define KERN_SWITCH_INCLUDE 1 1548 #include "kern/kern_switch.c"
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