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 40 #include <sys/param.h> 41 #include <sys/systm.h> 42 #include <sys/kernel.h> 43 #include <sys/ktr.h> 44 #include <sys/lock.h> 45 #include <sys/kthread.h> 46 #include <sys/mutex.h> 47 #include <sys/proc.h> 48 #include <sys/resourcevar.h> 49 #include <sys/sched.h> 50 #include <sys/smp.h> 51 #include <sys/sysctl.h> 52 #include <sys/sx.h> 53 #include <sys/turnstile.h> 54 #include <sys/umtx.h> 55 #include <machine/pcb.h> 56 #include <machine/smp.h> 57 58 #ifdef HWPMC_HOOKS 59 #include <sys/pmckern.h> 60 #endif 61 62 /* 63 * INVERSE_ESTCPU_WEIGHT is only suitable for statclock() frequencies in 64 * the range 100-256 Hz (approximately). 65 */ 66 #define ESTCPULIM(e) \ 67 min((e), INVERSE_ESTCPU_WEIGHT * (NICE_WEIGHT * (PRIO_MAX - PRIO_MIN) - \ 68 RQ_PPQ) + INVERSE_ESTCPU_WEIGHT - 1) 69 #ifdef SMP 70 #define INVERSE_ESTCPU_WEIGHT (8 * smp_cpus) 71 #else 72 #define INVERSE_ESTCPU_WEIGHT 8 /* 1 / (priorities per estcpu level). */ 73 #endif 74 #define NICE_WEIGHT 1 /* Priorities per nice level. */ 75 76 /* 77 * The schedulable entity that runs a context. 78 * This is an extension to the thread structure and is tailored to 79 * the requirements of this scheduler 80 */ 81 struct td_sched { 82 TAILQ_ENTRY(td_sched) ts_procq; /* (j/z) Run queue. */ 83 struct thread *ts_thread; /* (*) Active associated thread. */ 84 fixpt_t ts_pctcpu; /* (j) %cpu during p_swtime. */ 85 u_char ts_rqindex; /* (j) Run queue index. */ 86 int ts_cpticks; /* (j) Ticks of cpu time. */ 87 int ts_slptime; /* (j) Seconds !RUNNING. */ 88 struct runq *ts_runq; /* runq the thread is currently on */ 89 }; 90 91 /* flags kept in td_flags */ 92 #define TDF_DIDRUN TDF_SCHED0 /* thread actually ran. */ 93 #define TDF_EXIT TDF_SCHED1 /* thread is being killed. */ 94 #define TDF_BOUND TDF_SCHED2 95 96 #define ts_flags ts_thread->td_flags 97 #define TSF_DIDRUN TDF_DIDRUN /* thread actually ran. */ 98 #define TSF_EXIT TDF_EXIT /* thread is being killed. */ 99 #define TSF_BOUND TDF_BOUND /* stuck to one CPU */ 100 101 #define SKE_RUNQ_PCPU(ts) \ 102 ((ts)->ts_runq != 0 && (ts)->ts_runq != &runq) 103 104 static struct td_sched td_sched0; 105 struct mtx sched_lock; 106 107 static int sched_tdcnt; /* Total runnable threads in the system. */ 108 static int sched_quantum; /* Roundrobin scheduling quantum in ticks. */ 109 #define SCHED_QUANTUM (hz / 10) /* Default sched quantum */ 110 111 static struct callout roundrobin_callout; 112 113 static void setup_runqs(void); 114 static void roundrobin(void *arg); 115 static void schedcpu(void); 116 static void schedcpu_thread(void); 117 static void sched_priority(struct thread *td, u_char prio); 118 static void sched_setup(void *dummy); 119 static void maybe_resched(struct thread *td); 120 static void updatepri(struct thread *td); 121 static void resetpriority(struct thread *td); 122 static void resetpriority_thread(struct thread *td); 123 #ifdef SMP 124 static int forward_wakeup(int cpunum); 125 #endif 126 127 static struct kproc_desc sched_kp = { 128 "schedcpu", 129 schedcpu_thread, 130 NULL 131 }; 132 SYSINIT(schedcpu, SI_SUB_RUN_SCHEDULER, SI_ORDER_FIRST, kproc_start, &sched_kp) 133 SYSINIT(sched_setup, SI_SUB_RUN_QUEUE, SI_ORDER_FIRST, sched_setup, NULL) 134 135 /* 136 * Global run queue. 137 */ 138 static struct runq runq; 139 140 #ifdef SMP 141 /* 142 * Per-CPU run queues 143 */ 144 static struct runq runq_pcpu[MAXCPU]; 145 #endif 146 147 static void 148 setup_runqs(void) 149 { 150 #ifdef SMP 151 int i; 152 153 for (i = 0; i < MAXCPU; ++i) 154 runq_init(&runq_pcpu[i]); 155 #endif 156 157 runq_init(&runq); 158 } 159 160 static int 161 sysctl_kern_quantum(SYSCTL_HANDLER_ARGS) 162 { 163 int error, new_val; 164 165 new_val = sched_quantum * tick; 166 error = sysctl_handle_int(oidp, &new_val, 0, req); 167 if (error != 0 || req->newptr == NULL) 168 return (error); 169 if (new_val < tick) 170 return (EINVAL); 171 sched_quantum = new_val / tick; 172 hogticks = 2 * sched_quantum; 173 return (0); 174 } 175 176 SYSCTL_NODE(_kern, OID_AUTO, sched, CTLFLAG_RD, 0, "Scheduler"); 177 178 SYSCTL_STRING(_kern_sched, OID_AUTO, name, CTLFLAG_RD, "4BSD", 0, 179 "Scheduler name"); 180 181 SYSCTL_PROC(_kern_sched, OID_AUTO, quantum, CTLTYPE_INT | CTLFLAG_RW, 182 0, sizeof sched_quantum, sysctl_kern_quantum, "I", 183 "Roundrobin scheduling quantum in microseconds"); 184 185 #ifdef SMP 186 /* Enable forwarding of wakeups to all other cpus */ 187 SYSCTL_NODE(_kern_sched, OID_AUTO, ipiwakeup, CTLFLAG_RD, NULL, "Kernel SMP"); 188 189 static int forward_wakeup_enabled = 1; 190 SYSCTL_INT(_kern_sched_ipiwakeup, OID_AUTO, enabled, CTLFLAG_RW, 191 &forward_wakeup_enabled, 0, 192 "Forwarding of wakeup to idle CPUs"); 193 194 static int forward_wakeups_requested = 0; 195 SYSCTL_INT(_kern_sched_ipiwakeup, OID_AUTO, requested, CTLFLAG_RD, 196 &forward_wakeups_requested, 0, 197 "Requests for Forwarding of wakeup to idle CPUs"); 198 199 static int forward_wakeups_delivered = 0; 200 SYSCTL_INT(_kern_sched_ipiwakeup, OID_AUTO, delivered, CTLFLAG_RD, 201 &forward_wakeups_delivered, 0, 202 "Completed Forwarding of wakeup to idle CPUs"); 203 204 static int forward_wakeup_use_mask = 1; 205 SYSCTL_INT(_kern_sched_ipiwakeup, OID_AUTO, usemask, CTLFLAG_RW, 206 &forward_wakeup_use_mask, 0, 207 "Use the mask of idle cpus"); 208 209 static int forward_wakeup_use_loop = 0; 210 SYSCTL_INT(_kern_sched_ipiwakeup, OID_AUTO, useloop, CTLFLAG_RW, 211 &forward_wakeup_use_loop, 0, 212 "Use a loop to find idle cpus"); 213 214 static int forward_wakeup_use_single = 0; 215 SYSCTL_INT(_kern_sched_ipiwakeup, OID_AUTO, onecpu, CTLFLAG_RW, 216 &forward_wakeup_use_single, 0, 217 "Only signal one idle cpu"); 218 219 static int forward_wakeup_use_htt = 0; 220 SYSCTL_INT(_kern_sched_ipiwakeup, OID_AUTO, htt2, CTLFLAG_RW, 221 &forward_wakeup_use_htt, 0, 222 "account for htt"); 223 224 #endif 225 #if 0 226 static int sched_followon = 0; 227 SYSCTL_INT(_kern_sched, OID_AUTO, followon, CTLFLAG_RW, 228 &sched_followon, 0, 229 "allow threads to share a quantum"); 230 #endif 231 232 static __inline void 233 sched_load_add(void) 234 { 235 sched_tdcnt++; 236 CTR1(KTR_SCHED, "global load: %d", sched_tdcnt); 237 } 238 239 static __inline void 240 sched_load_rem(void) 241 { 242 sched_tdcnt--; 243 CTR1(KTR_SCHED, "global load: %d", sched_tdcnt); 244 } 245 /* 246 * Arrange to reschedule if necessary, taking the priorities and 247 * schedulers into account. 248 */ 249 static void 250 maybe_resched(struct thread *td) 251 { 252 253 THREAD_LOCK_ASSERT(td, MA_OWNED); 254 if (td->td_priority < curthread->td_priority) 255 curthread->td_flags |= TDF_NEEDRESCHED; 256 } 257 258 /* 259 * Force switch among equal priority processes every 100ms. 260 * We don't actually need to force a context switch of the current process. 261 * The act of firing the event triggers a context switch to softclock() and 262 * then switching back out again which is equivalent to a preemption, thus 263 * no further work is needed on the local CPU. 264 */ 265 /* ARGSUSED */ 266 static void 267 roundrobin(void *arg) 268 { 269 270 #ifdef SMP 271 mtx_lock_spin(&sched_lock); 272 forward_roundrobin(); 273 mtx_unlock_spin(&sched_lock); 274 #endif 275 276 callout_reset(&roundrobin_callout, sched_quantum, roundrobin, NULL); 277 } 278 279 /* 280 * Constants for digital decay and forget: 281 * 90% of (td_estcpu) usage in 5 * loadav time 282 * 95% of (ts_pctcpu) usage in 60 seconds (load insensitive) 283 * Note that, as ps(1) mentions, this can let percentages 284 * total over 100% (I've seen 137.9% for 3 processes). 285 * 286 * Note that schedclock() updates td_estcpu and p_cpticks asynchronously. 287 * 288 * We wish to decay away 90% of td_estcpu in (5 * loadavg) seconds. 289 * That is, the system wants to compute a value of decay such 290 * that the following for loop: 291 * for (i = 0; i < (5 * loadavg); i++) 292 * td_estcpu *= decay; 293 * will compute 294 * td_estcpu *= 0.1; 295 * for all values of loadavg: 296 * 297 * Mathematically this loop can be expressed by saying: 298 * decay ** (5 * loadavg) ~= .1 299 * 300 * The system computes decay as: 301 * decay = (2 * loadavg) / (2 * loadavg + 1) 302 * 303 * We wish to prove that the system's computation of decay 304 * will always fulfill the equation: 305 * decay ** (5 * loadavg) ~= .1 306 * 307 * If we compute b as: 308 * b = 2 * loadavg 309 * then 310 * decay = b / (b + 1) 311 * 312 * We now need to prove two things: 313 * 1) Given factor ** (5 * loadavg) ~= .1, prove factor == b/(b+1) 314 * 2) Given b/(b+1) ** power ~= .1, prove power == (5 * loadavg) 315 * 316 * Facts: 317 * For x close to zero, exp(x) =~ 1 + x, since 318 * exp(x) = 0! + x**1/1! + x**2/2! + ... . 319 * therefore exp(-1/b) =~ 1 - (1/b) = (b-1)/b. 320 * For x close to zero, ln(1+x) =~ x, since 321 * ln(1+x) = x - x**2/2 + x**3/3 - ... -1 < x < 1 322 * therefore ln(b/(b+1)) = ln(1 - 1/(b+1)) =~ -1/(b+1). 323 * ln(.1) =~ -2.30 324 * 325 * Proof of (1): 326 * Solve (factor)**(power) =~ .1 given power (5*loadav): 327 * solving for factor, 328 * ln(factor) =~ (-2.30/5*loadav), or 329 * factor =~ exp(-1/((5/2.30)*loadav)) =~ exp(-1/(2*loadav)) = 330 * exp(-1/b) =~ (b-1)/b =~ b/(b+1). QED 331 * 332 * Proof of (2): 333 * Solve (factor)**(power) =~ .1 given factor == (b/(b+1)): 334 * solving for power, 335 * power*ln(b/(b+1)) =~ -2.30, or 336 * power =~ 2.3 * (b + 1) = 4.6*loadav + 2.3 =~ 5*loadav. QED 337 * 338 * Actual power values for the implemented algorithm are as follows: 339 * loadav: 1 2 3 4 340 * power: 5.68 10.32 14.94 19.55 341 */ 342 343 /* calculations for digital decay to forget 90% of usage in 5*loadav sec */ 344 #define loadfactor(loadav) (2 * (loadav)) 345 #define decay_cpu(loadfac, cpu) (((loadfac) * (cpu)) / ((loadfac) + FSCALE)) 346 347 /* decay 95% of `ts_pctcpu' in 60 seconds; see CCPU_SHIFT before changing */ 348 static fixpt_t ccpu = 0.95122942450071400909 * FSCALE; /* exp(-1/20) */ 349 SYSCTL_INT(_kern, OID_AUTO, ccpu, CTLFLAG_RD, &ccpu, 0, ""); 350 351 /* 352 * If `ccpu' is not equal to `exp(-1/20)' and you still want to use the 353 * faster/more-accurate formula, you'll have to estimate CCPU_SHIFT below 354 * and possibly adjust FSHIFT in "param.h" so that (FSHIFT >= CCPU_SHIFT). 355 * 356 * To estimate CCPU_SHIFT for exp(-1/20), the following formula was used: 357 * 1 - exp(-1/20) ~= 0.0487 ~= 0.0488 == 1 (fixed pt, *11* bits). 358 * 359 * If you don't want to bother with the faster/more-accurate formula, you 360 * can set CCPU_SHIFT to (FSHIFT + 1) which will use a slower/less-accurate 361 * (more general) method of calculating the %age of CPU used by a process. 362 */ 363 #define CCPU_SHIFT 11 364 365 /* 366 * Recompute process priorities, every hz ticks. 367 * MP-safe, called without the Giant mutex. 368 */ 369 /* ARGSUSED */ 370 static void 371 schedcpu(void) 372 { 373 register fixpt_t loadfac = loadfactor(averunnable.ldavg[0]); 374 struct thread *td; 375 struct proc *p; 376 struct td_sched *ts; 377 int awake, realstathz; 378 379 realstathz = stathz ? stathz : hz; 380 sx_slock(&allproc_lock); 381 FOREACH_PROC_IN_SYSTEM(p) { 382 PROC_SLOCK(p); 383 FOREACH_THREAD_IN_PROC(p, td) { 384 awake = 0; 385 thread_lock(td); 386 ts = td->td_sched; 387 /* 388 * Increment sleep time (if sleeping). We 389 * ignore overflow, as above. 390 */ 391 /* 392 * The td_sched slptimes are not touched in wakeup 393 * because the thread may not HAVE everything in 394 * memory? XXX I think this is out of date. 395 */ 396 if (TD_ON_RUNQ(td)) { 397 awake = 1; 398 ts->ts_flags &= ~TSF_DIDRUN; 399 } else if (TD_IS_RUNNING(td)) { 400 awake = 1; 401 /* Do not clear TSF_DIDRUN */ 402 } else if (ts->ts_flags & TSF_DIDRUN) { 403 awake = 1; 404 ts->ts_flags &= ~TSF_DIDRUN; 405 } 406 407 /* 408 * ts_pctcpu is only for ps and ttyinfo(). 409 * Do it per td_sched, and add them up at the end? 410 * XXXKSE 411 */ 412 ts->ts_pctcpu = (ts->ts_pctcpu * ccpu) >> FSHIFT; 413 /* 414 * If the td_sched has been idle the entire second, 415 * stop recalculating its priority until 416 * it wakes up. 417 */ 418 if (ts->ts_cpticks != 0) { 419 #if (FSHIFT >= CCPU_SHIFT) 420 ts->ts_pctcpu += (realstathz == 100) 421 ? ((fixpt_t) ts->ts_cpticks) << 422 (FSHIFT - CCPU_SHIFT) : 423 100 * (((fixpt_t) ts->ts_cpticks) 424 << (FSHIFT - CCPU_SHIFT)) / realstathz; 425 #else 426 ts->ts_pctcpu += ((FSCALE - ccpu) * 427 (ts->ts_cpticks * 428 FSCALE / realstathz)) >> FSHIFT; 429 #endif 430 ts->ts_cpticks = 0; 431 } 432 /* 433 * If there are ANY running threads in this process, 434 * then don't count it as sleeping. 435 XXX this is broken 436 437 */ 438 if (awake) { 439 if (ts->ts_slptime > 1) { 440 /* 441 * In an ideal world, this should not 442 * happen, because whoever woke us 443 * up from the long sleep should have 444 * unwound the slptime and reset our 445 * priority before we run at the stale 446 * priority. Should KASSERT at some 447 * point when all the cases are fixed. 448 */ 449 updatepri(td); 450 } 451 ts->ts_slptime = 0; 452 } else 453 ts->ts_slptime++; 454 if (ts->ts_slptime > 1) { 455 thread_unlock(td); 456 continue; 457 } 458 td->td_estcpu = decay_cpu(loadfac, td->td_estcpu); 459 resetpriority(td); 460 resetpriority_thread(td); 461 thread_unlock(td); 462 } /* end of thread loop */ 463 PROC_SUNLOCK(p); 464 } /* end of process loop */ 465 sx_sunlock(&allproc_lock); 466 } 467 468 /* 469 * Main loop for a kthread that executes schedcpu once a second. 470 */ 471 static void 472 schedcpu_thread(void) 473 { 474 475 for (;;) { 476 schedcpu(); 477 pause("-", hz); 478 } 479 } 480 481 /* 482 * Recalculate the priority of a process after it has slept for a while. 483 * For all load averages >= 1 and max td_estcpu of 255, sleeping for at 484 * least six times the loadfactor will decay td_estcpu to zero. 485 */ 486 static void 487 updatepri(struct thread *td) 488 { 489 struct td_sched *ts; 490 fixpt_t loadfac; 491 unsigned int newcpu; 492 493 ts = td->td_sched; 494 loadfac = loadfactor(averunnable.ldavg[0]); 495 if (ts->ts_slptime > 5 * loadfac) 496 td->td_estcpu = 0; 497 else { 498 newcpu = td->td_estcpu; 499 ts->ts_slptime--; /* was incremented in schedcpu() */ 500 while (newcpu && --ts->ts_slptime) 501 newcpu = decay_cpu(loadfac, newcpu); 502 td->td_estcpu = newcpu; 503 } 504 } 505 506 /* 507 * Compute the priority of a process when running in user mode. 508 * Arrange to reschedule if the resulting priority is better 509 * than that of the current process. 510 */ 511 static void 512 resetpriority(struct thread *td) 513 { 514 register unsigned int newpriority; 515 516 if (td->td_pri_class == PRI_TIMESHARE) { 517 newpriority = PUSER + td->td_estcpu / INVERSE_ESTCPU_WEIGHT + 518 NICE_WEIGHT * (td->td_proc->p_nice - PRIO_MIN); 519 newpriority = min(max(newpriority, PRI_MIN_TIMESHARE), 520 PRI_MAX_TIMESHARE); 521 sched_user_prio(td, newpriority); 522 } 523 } 524 525 /* 526 * Update the thread's priority when the associated process's user 527 * priority changes. 528 */ 529 static void 530 resetpriority_thread(struct thread *td) 531 { 532 533 /* Only change threads with a time sharing user priority. */ 534 if (td->td_priority < PRI_MIN_TIMESHARE || 535 td->td_priority > PRI_MAX_TIMESHARE) 536 return; 537 538 /* XXX the whole needresched thing is broken, but not silly. */ 539 maybe_resched(td); 540 541 sched_prio(td, td->td_user_pri); 542 } 543 544 /* ARGSUSED */ 545 static void 546 sched_setup(void *dummy) 547 { 548 setup_runqs(); 549 550 if (sched_quantum == 0) 551 sched_quantum = SCHED_QUANTUM; 552 hogticks = 2 * sched_quantum; 553 554 callout_init(&roundrobin_callout, CALLOUT_MPSAFE); 555 556 /* Kick off timeout driven events by calling first time. */ 557 roundrobin(NULL); 558 559 /* Account for thread0. */ 560 sched_load_add(); 561 } 562 563 /* External interfaces start here */ 564 /* 565 * Very early in the boot some setup of scheduler-specific 566 * parts of proc0 and of some scheduler resources needs to be done. 567 * Called from: 568 * proc0_init() 569 */ 570 void 571 schedinit(void) 572 { 573 /* 574 * Set up the scheduler specific parts of proc0. 575 */ 576 proc0.p_sched = NULL; /* XXX */ 577 thread0.td_sched = &td_sched0; 578 thread0.td_lock = &sched_lock; 579 td_sched0.ts_thread = &thread0; 580 mtx_init(&sched_lock, "sched lock", NULL, MTX_SPIN | MTX_RECURSE); 581 } 582 583 int 584 sched_runnable(void) 585 { 586 #ifdef SMP 587 return runq_check(&runq) + runq_check(&runq_pcpu[PCPU_GET(cpuid)]); 588 #else 589 return runq_check(&runq); 590 #endif 591 } 592 593 int 594 sched_rr_interval(void) 595 { 596 if (sched_quantum == 0) 597 sched_quantum = SCHED_QUANTUM; 598 return (sched_quantum); 599 } 600 601 /* 602 * We adjust the priority of the current process. The priority of 603 * a process gets worse as it accumulates CPU time. The cpu usage 604 * estimator (td_estcpu) is increased here. resetpriority() will 605 * compute a different priority each time td_estcpu increases by 606 * INVERSE_ESTCPU_WEIGHT 607 * (until MAXPRI is reached). The cpu usage estimator ramps up 608 * quite quickly when the process is running (linearly), and decays 609 * away exponentially, at a rate which is proportionally slower when 610 * the system is busy. The basic principle is that the system will 611 * 90% forget that the process used a lot of CPU time in 5 * loadav 612 * seconds. This causes the system to favor processes which haven't 613 * run much recently, and to round-robin among other processes. 614 */ 615 void 616 sched_clock(struct thread *td) 617 { 618 struct td_sched *ts; 619 620 THREAD_LOCK_ASSERT(td, MA_OWNED); 621 ts = td->td_sched; 622 623 ts->ts_cpticks++; 624 td->td_estcpu = ESTCPULIM(td->td_estcpu + 1); 625 if ((td->td_estcpu % INVERSE_ESTCPU_WEIGHT) == 0) { 626 resetpriority(td); 627 resetpriority_thread(td); 628 } 629 } 630 631 /* 632 * charge childs scheduling cpu usage to parent. 633 */ 634 void 635 sched_exit(struct proc *p, struct thread *td) 636 { 637 638 CTR3(KTR_SCHED, "sched_exit: %p(%s) prio %d", 639 td, td->td_proc->p_comm, td->td_priority); 640 PROC_SLOCK_ASSERT(p, MA_OWNED); 641 sched_exit_thread(FIRST_THREAD_IN_PROC(p), td); 642 } 643 644 void 645 sched_exit_thread(struct thread *td, struct thread *child) 646 { 647 648 CTR3(KTR_SCHED, "sched_exit_thread: %p(%s) prio %d", 649 child, child->td_proc->p_comm, child->td_priority); 650 thread_lock(td); 651 td->td_estcpu = ESTCPULIM(td->td_estcpu + child->td_estcpu); 652 thread_unlock(td); 653 mtx_lock_spin(&sched_lock); 654 if ((child->td_proc->p_flag & P_NOLOAD) == 0) 655 sched_load_rem(); 656 mtx_unlock_spin(&sched_lock); 657 } 658 659 void 660 sched_fork(struct thread *td, struct thread *childtd) 661 { 662 sched_fork_thread(td, childtd); 663 } 664 665 void 666 sched_fork_thread(struct thread *td, struct thread *childtd) 667 { 668 childtd->td_estcpu = td->td_estcpu; 669 childtd->td_lock = &sched_lock; 670 sched_newthread(childtd); 671 } 672 673 void 674 sched_nice(struct proc *p, int nice) 675 { 676 struct thread *td; 677 678 PROC_LOCK_ASSERT(p, MA_OWNED); 679 PROC_SLOCK_ASSERT(p, MA_OWNED); 680 p->p_nice = nice; 681 FOREACH_THREAD_IN_PROC(p, td) { 682 thread_lock(td); 683 resetpriority(td); 684 resetpriority_thread(td); 685 thread_unlock(td); 686 } 687 } 688 689 void 690 sched_class(struct thread *td, int class) 691 { 692 THREAD_LOCK_ASSERT(td, MA_OWNED); 693 td->td_pri_class = class; 694 } 695 696 /* 697 * Adjust the priority of a thread. 698 */ 699 static void 700 sched_priority(struct thread *td, u_char prio) 701 { 702 CTR6(KTR_SCHED, "sched_prio: %p(%s) prio %d newprio %d by %p(%s)", 703 td, td->td_proc->p_comm, td->td_priority, prio, curthread, 704 curthread->td_proc->p_comm); 705 706 THREAD_LOCK_ASSERT(td, MA_OWNED); 707 if (td->td_priority == prio) 708 return; 709 td->td_priority = prio; 710 if (TD_ON_RUNQ(td) && 711 td->td_sched->ts_rqindex != (prio / RQ_PPQ)) { 712 sched_rem(td); 713 sched_add(td, SRQ_BORING); 714 } 715 } 716 717 /* 718 * Update a thread's priority when it is lent another thread's 719 * priority. 720 */ 721 void 722 sched_lend_prio(struct thread *td, u_char prio) 723 { 724 725 td->td_flags |= TDF_BORROWING; 726 sched_priority(td, prio); 727 } 728 729 /* 730 * Restore a thread's priority when priority propagation is 731 * over. The prio argument is the minimum priority the thread 732 * needs to have to satisfy other possible priority lending 733 * requests. If the thread's regulary priority is less 734 * important than prio the thread will keep a priority boost 735 * of prio. 736 */ 737 void 738 sched_unlend_prio(struct thread *td, u_char prio) 739 { 740 u_char base_pri; 741 742 if (td->td_base_pri >= PRI_MIN_TIMESHARE && 743 td->td_base_pri <= PRI_MAX_TIMESHARE) 744 base_pri = td->td_user_pri; 745 else 746 base_pri = td->td_base_pri; 747 if (prio >= base_pri) { 748 td->td_flags &= ~TDF_BORROWING; 749 sched_prio(td, base_pri); 750 } else 751 sched_lend_prio(td, prio); 752 } 753 754 void 755 sched_prio(struct thread *td, u_char prio) 756 { 757 u_char oldprio; 758 759 /* First, update the base priority. */ 760 td->td_base_pri = prio; 761 762 /* 763 * If the thread is borrowing another thread's priority, don't ever 764 * lower the priority. 765 */ 766 if (td->td_flags & TDF_BORROWING && td->td_priority < prio) 767 return; 768 769 /* Change the real priority. */ 770 oldprio = td->td_priority; 771 sched_priority(td, prio); 772 773 /* 774 * If the thread is on a turnstile, then let the turnstile update 775 * its state. 776 */ 777 if (TD_ON_LOCK(td) && oldprio != prio) 778 turnstile_adjust(td, oldprio); 779 } 780 781 void 782 sched_user_prio(struct thread *td, u_char prio) 783 { 784 u_char oldprio; 785 786 THREAD_LOCK_ASSERT(td, MA_OWNED); 787 td->td_base_user_pri = prio; 788 if (td->td_flags & TDF_UBORROWING && td->td_user_pri <= prio) 789 return; 790 oldprio = td->td_user_pri; 791 td->td_user_pri = prio; 792 } 793 794 void 795 sched_lend_user_prio(struct thread *td, u_char prio) 796 { 797 u_char oldprio; 798 799 THREAD_LOCK_ASSERT(td, MA_OWNED); 800 td->td_flags |= TDF_UBORROWING; 801 802 oldprio = td->td_user_pri; 803 td->td_user_pri = prio; 804 } 805 806 void 807 sched_unlend_user_prio(struct thread *td, u_char prio) 808 { 809 u_char base_pri; 810 811 THREAD_LOCK_ASSERT(td, MA_OWNED); 812 base_pri = td->td_base_user_pri; 813 if (prio >= base_pri) { 814 td->td_flags &= ~TDF_UBORROWING; 815 sched_user_prio(td, base_pri); 816 } else { 817 sched_lend_user_prio(td, prio); 818 } 819 } 820 821 void 822 sched_sleep(struct thread *td) 823 { 824 825 THREAD_LOCK_ASSERT(td, MA_OWNED); 826 td->td_slptick = ticks; 827 td->td_sched->ts_slptime = 0; 828 } 829 830 void 831 sched_switch(struct thread *td, struct thread *newtd, int flags) 832 { 833 struct td_sched *ts; 834 struct proc *p; 835 836 ts = td->td_sched; 837 p = td->td_proc; 838 839 THREAD_LOCK_ASSERT(td, MA_OWNED); 840 /* 841 * Switch to the sched lock to fix things up and pick 842 * a new thread. 843 */ 844 if (td->td_lock != &sched_lock) { 845 mtx_lock_spin(&sched_lock); 846 thread_unlock(td); 847 } 848 849 if ((p->p_flag & P_NOLOAD) == 0) 850 sched_load_rem(); 851 852 if (newtd) 853 newtd->td_flags |= (td->td_flags & TDF_NEEDRESCHED); 854 855 td->td_lastcpu = td->td_oncpu; 856 td->td_flags &= ~TDF_NEEDRESCHED; 857 td->td_owepreempt = 0; 858 td->td_oncpu = NOCPU; 859 /* 860 * At the last moment, if this thread is still marked RUNNING, 861 * then put it back on the run queue as it has not been suspended 862 * or stopped or any thing else similar. We never put the idle 863 * threads on the run queue, however. 864 */ 865 if (td->td_flags & TDF_IDLETD) { 866 TD_SET_CAN_RUN(td); 867 #ifdef SMP 868 idle_cpus_mask &= ~PCPU_GET(cpumask); 869 #endif 870 } else { 871 if (TD_IS_RUNNING(td)) { 872 /* Put us back on the run queue. */ 873 sched_add(td, (flags & SW_PREEMPT) ? 874 SRQ_OURSELF|SRQ_YIELDING|SRQ_PREEMPTED : 875 SRQ_OURSELF|SRQ_YIELDING); 876 } 877 } 878 if (newtd) { 879 /* 880 * The thread we are about to run needs to be counted 881 * as if it had been added to the run queue and selected. 882 * It came from: 883 * * A preemption 884 * * An upcall 885 * * A followon 886 */ 887 KASSERT((newtd->td_inhibitors == 0), 888 ("trying to run inhibited thread")); 889 newtd->td_sched->ts_flags |= TSF_DIDRUN; 890 TD_SET_RUNNING(newtd); 891 if ((newtd->td_proc->p_flag & P_NOLOAD) == 0) 892 sched_load_add(); 893 } else { 894 newtd = choosethread(); 895 } 896 MPASS(newtd->td_lock == &sched_lock); 897 898 if (td != newtd) { 899 #ifdef HWPMC_HOOKS 900 if (PMC_PROC_IS_USING_PMCS(td->td_proc)) 901 PMC_SWITCH_CONTEXT(td, PMC_FN_CSW_OUT); 902 #endif 903 904 /* I feel sleepy */ 905 cpu_switch(td, newtd, td->td_lock); 906 /* 907 * Where am I? What year is it? 908 * We are in the same thread that went to sleep above, 909 * but any amount of time may have passed. All out context 910 * will still be available as will local variables. 911 * PCPU values however may have changed as we may have 912 * changed CPU so don't trust cached values of them. 913 * New threads will go to fork_exit() instead of here 914 * so if you change things here you may need to change 915 * things there too. 916 * If the thread above was exiting it will never wake 917 * up again here, so either it has saved everything it 918 * needed to, or the thread_wait() or wait() will 919 * need to reap it. 920 */ 921 #ifdef HWPMC_HOOKS 922 if (PMC_PROC_IS_USING_PMCS(td->td_proc)) 923 PMC_SWITCH_CONTEXT(td, PMC_FN_CSW_IN); 924 #endif 925 } 926 927 #ifdef SMP 928 if (td->td_flags & TDF_IDLETD) 929 idle_cpus_mask |= PCPU_GET(cpumask); 930 #endif 931 sched_lock.mtx_lock = (uintptr_t)td; 932 td->td_oncpu = PCPU_GET(cpuid); 933 MPASS(td->td_lock == &sched_lock); 934 } 935 936 void 937 sched_wakeup(struct thread *td) 938 { 939 struct td_sched *ts; 940 941 THREAD_LOCK_ASSERT(td, MA_OWNED); 942 ts = td->td_sched; 943 if (ts->ts_slptime > 1) { 944 updatepri(td); 945 resetpriority(td); 946 } 947 td->td_slptick = ticks; 948 ts->ts_slptime = 0; 949 sched_add(td, SRQ_BORING); 950 } 951 952 #ifdef SMP 953 /* enable HTT_2 if you have a 2-way HTT cpu.*/ 954 static int 955 forward_wakeup(int cpunum) 956 { 957 cpumask_t map, me, dontuse; 958 cpumask_t map2; 959 struct pcpu *pc; 960 cpumask_t id, map3; 961 962 mtx_assert(&sched_lock, MA_OWNED); 963 964 CTR0(KTR_RUNQ, "forward_wakeup()"); 965 966 if ((!forward_wakeup_enabled) || 967 (forward_wakeup_use_mask == 0 && forward_wakeup_use_loop == 0)) 968 return (0); 969 if (!smp_started || cold || panicstr) 970 return (0); 971 972 forward_wakeups_requested++; 973 974 /* 975 * check the idle mask we received against what we calculated before 976 * in the old version. 977 */ 978 me = PCPU_GET(cpumask); 979 /* 980 * don't bother if we should be doing it ourself.. 981 */ 982 if ((me & idle_cpus_mask) && (cpunum == NOCPU || me == (1 << cpunum))) 983 return (0); 984 985 dontuse = me | stopped_cpus | hlt_cpus_mask; 986 map3 = 0; 987 if (forward_wakeup_use_loop) { 988 SLIST_FOREACH(pc, &cpuhead, pc_allcpu) { 989 id = pc->pc_cpumask; 990 if ( (id & dontuse) == 0 && 991 pc->pc_curthread == pc->pc_idlethread) { 992 map3 |= id; 993 } 994 } 995 } 996 997 if (forward_wakeup_use_mask) { 998 map = 0; 999 map = idle_cpus_mask & ~dontuse; 1000 1001 /* If they are both on, compare and use loop if different */ 1002 if (forward_wakeup_use_loop) { 1003 if (map != map3) { 1004 printf("map (%02X) != map3 (%02X)\n", 1005 map, map3); 1006 map = map3; 1007 } 1008 } 1009 } else { 1010 map = map3; 1011 } 1012 /* If we only allow a specific CPU, then mask off all the others */ 1013 if (cpunum != NOCPU) { 1014 KASSERT((cpunum <= mp_maxcpus),("forward_wakeup: bad cpunum.")); 1015 map &= (1 << cpunum); 1016 } else { 1017 /* Try choose an idle die. */ 1018 if (forward_wakeup_use_htt) { 1019 map2 = (map & (map >> 1)) & 0x5555; 1020 if (map2) { 1021 map = map2; 1022 } 1023 } 1024 1025 /* set only one bit */ 1026 if (forward_wakeup_use_single) { 1027 map = map & ((~map) + 1); 1028 } 1029 } 1030 if (map) { 1031 forward_wakeups_delivered++; 1032 ipi_selected(map, IPI_AST); 1033 return (1); 1034 } 1035 if (cpunum == NOCPU) 1036 printf("forward_wakeup: Idle processor not found\n"); 1037 return (0); 1038 } 1039 #endif 1040 1041 #ifdef SMP 1042 static void kick_other_cpu(int pri,int cpuid); 1043 1044 static void 1045 kick_other_cpu(int pri,int cpuid) 1046 { 1047 struct pcpu * pcpu = pcpu_find(cpuid); 1048 int cpri = pcpu->pc_curthread->td_priority; 1049 1050 if (idle_cpus_mask & pcpu->pc_cpumask) { 1051 forward_wakeups_delivered++; 1052 ipi_selected(pcpu->pc_cpumask, IPI_AST); 1053 return; 1054 } 1055 1056 if (pri >= cpri) 1057 return; 1058 1059 #if defined(IPI_PREEMPTION) && defined(PREEMPTION) 1060 #if !defined(FULL_PREEMPTION) 1061 if (pri <= PRI_MAX_ITHD) 1062 #endif /* ! FULL_PREEMPTION */ 1063 { 1064 ipi_selected(pcpu->pc_cpumask, IPI_PREEMPT); 1065 return; 1066 } 1067 #endif /* defined(IPI_PREEMPTION) && defined(PREEMPTION) */ 1068 1069 pcpu->pc_curthread->td_flags |= TDF_NEEDRESCHED; 1070 ipi_selected( pcpu->pc_cpumask , IPI_AST); 1071 return; 1072 } 1073 #endif /* SMP */ 1074 1075 void 1076 sched_add(struct thread *td, int flags) 1077 #ifdef SMP 1078 { 1079 struct td_sched *ts; 1080 int forwarded = 0; 1081 int cpu; 1082 int single_cpu = 0; 1083 1084 ts = td->td_sched; 1085 THREAD_LOCK_ASSERT(td, MA_OWNED); 1086 KASSERT((td->td_inhibitors == 0), 1087 ("sched_add: trying to run inhibited thread")); 1088 KASSERT((TD_CAN_RUN(td) || TD_IS_RUNNING(td)), 1089 ("sched_add: bad thread state")); 1090 KASSERT(td->td_flags & TDF_INMEM, 1091 ("sched_add: thread swapped out")); 1092 CTR5(KTR_SCHED, "sched_add: %p(%s) prio %d by %p(%s)", 1093 td, td->td_proc->p_comm, td->td_priority, curthread, 1094 curthread->td_proc->p_comm); 1095 /* 1096 * Now that the thread is moving to the run-queue, set the lock 1097 * to the scheduler's lock. 1098 */ 1099 if (td->td_lock != &sched_lock) { 1100 mtx_lock_spin(&sched_lock); 1101 thread_lock_set(td, &sched_lock); 1102 } 1103 TD_SET_RUNQ(td); 1104 1105 if (td->td_pinned != 0) { 1106 cpu = td->td_lastcpu; 1107 ts->ts_runq = &runq_pcpu[cpu]; 1108 single_cpu = 1; 1109 CTR3(KTR_RUNQ, 1110 "sched_add: Put td_sched:%p(td:%p) on cpu%d runq", ts, td, cpu); 1111 } else if ((ts)->ts_flags & TSF_BOUND) { 1112 /* Find CPU from bound runq */ 1113 KASSERT(SKE_RUNQ_PCPU(ts),("sched_add: bound td_sched not on cpu runq")); 1114 cpu = ts->ts_runq - &runq_pcpu[0]; 1115 single_cpu = 1; 1116 CTR3(KTR_RUNQ, 1117 "sched_add: Put td_sched:%p(td:%p) on cpu%d runq", ts, td, cpu); 1118 } else { 1119 CTR2(KTR_RUNQ, 1120 "sched_add: adding td_sched:%p (td:%p) to gbl runq", ts, td); 1121 cpu = NOCPU; 1122 ts->ts_runq = &runq; 1123 } 1124 1125 if (single_cpu && (cpu != PCPU_GET(cpuid))) { 1126 kick_other_cpu(td->td_priority,cpu); 1127 } else { 1128 1129 if (!single_cpu) { 1130 cpumask_t me = PCPU_GET(cpumask); 1131 int idle = idle_cpus_mask & me; 1132 1133 if (!idle && ((flags & SRQ_INTR) == 0) && 1134 (idle_cpus_mask & ~(hlt_cpus_mask | me))) 1135 forwarded = forward_wakeup(cpu); 1136 } 1137 1138 if (!forwarded) { 1139 if ((flags & SRQ_YIELDING) == 0 && maybe_preempt(td)) 1140 return; 1141 else 1142 maybe_resched(td); 1143 } 1144 } 1145 1146 if ((td->td_proc->p_flag & P_NOLOAD) == 0) 1147 sched_load_add(); 1148 runq_add(ts->ts_runq, ts, flags); 1149 } 1150 #else /* SMP */ 1151 { 1152 struct td_sched *ts; 1153 ts = td->td_sched; 1154 THREAD_LOCK_ASSERT(td, MA_OWNED); 1155 KASSERT((td->td_inhibitors == 0), 1156 ("sched_add: trying to run inhibited thread")); 1157 KASSERT((TD_CAN_RUN(td) || TD_IS_RUNNING(td)), 1158 ("sched_add: bad thread state")); 1159 KASSERT(td->td_flags & TDF_INMEM, 1160 ("sched_add: thread swapped out")); 1161 CTR5(KTR_SCHED, "sched_add: %p(%s) prio %d by %p(%s)", 1162 td, td->td_proc->p_comm, td->td_priority, curthread, 1163 curthread->td_proc->p_comm); 1164 /* 1165 * Now that the thread is moving to the run-queue, set the lock 1166 * to the scheduler's lock. 1167 */ 1168 if (td->td_lock != &sched_lock) { 1169 mtx_lock_spin(&sched_lock); 1170 thread_lock_set(td, &sched_lock); 1171 } 1172 TD_SET_RUNQ(td); 1173 CTR2(KTR_RUNQ, "sched_add: adding td_sched:%p (td:%p) to runq", ts, td); 1174 ts->ts_runq = &runq; 1175 1176 /* 1177 * If we are yielding (on the way out anyhow) 1178 * or the thread being saved is US, 1179 * then don't try be smart about preemption 1180 * or kicking off another CPU 1181 * as it won't help and may hinder. 1182 * In the YIEDLING case, we are about to run whoever is 1183 * being put in the queue anyhow, and in the 1184 * OURSELF case, we are puting ourself on the run queue 1185 * which also only happens when we are about to yield. 1186 */ 1187 if((flags & SRQ_YIELDING) == 0) { 1188 if (maybe_preempt(td)) 1189 return; 1190 } 1191 if ((td->td_proc->p_flag & P_NOLOAD) == 0) 1192 sched_load_add(); 1193 runq_add(ts->ts_runq, ts, flags); 1194 maybe_resched(td); 1195 } 1196 #endif /* SMP */ 1197 1198 void 1199 sched_rem(struct thread *td) 1200 { 1201 struct td_sched *ts; 1202 1203 ts = td->td_sched; 1204 KASSERT(td->td_flags & TDF_INMEM, 1205 ("sched_rem: thread swapped out")); 1206 KASSERT(TD_ON_RUNQ(td), 1207 ("sched_rem: thread not on run queue")); 1208 mtx_assert(&sched_lock, MA_OWNED); 1209 CTR5(KTR_SCHED, "sched_rem: %p(%s) prio %d by %p(%s)", 1210 td, td->td_proc->p_comm, td->td_priority, curthread, 1211 curthread->td_proc->p_comm); 1212 1213 if ((td->td_proc->p_flag & P_NOLOAD) == 0) 1214 sched_load_rem(); 1215 runq_remove(ts->ts_runq, ts); 1216 TD_SET_CAN_RUN(td); 1217 } 1218 1219 /* 1220 * Select threads to run. 1221 * Notice that the running threads still consume a slot. 1222 */ 1223 struct thread * 1224 sched_choose(void) 1225 { 1226 struct td_sched *ts; 1227 struct runq *rq; 1228 1229 mtx_assert(&sched_lock, MA_OWNED); 1230 #ifdef SMP 1231 struct td_sched *kecpu; 1232 1233 rq = &runq; 1234 ts = runq_choose(&runq); 1235 kecpu = runq_choose(&runq_pcpu[PCPU_GET(cpuid)]); 1236 1237 if (ts == NULL || 1238 (kecpu != NULL && 1239 kecpu->ts_thread->td_priority < ts->ts_thread->td_priority)) { 1240 CTR2(KTR_RUNQ, "choosing td_sched %p from pcpu runq %d", kecpu, 1241 PCPU_GET(cpuid)); 1242 ts = kecpu; 1243 rq = &runq_pcpu[PCPU_GET(cpuid)]; 1244 } else { 1245 CTR1(KTR_RUNQ, "choosing td_sched %p from main runq", ts); 1246 } 1247 1248 #else 1249 rq = &runq; 1250 ts = runq_choose(&runq); 1251 #endif 1252 1253 if (ts) { 1254 runq_remove(rq, ts); 1255 ts->ts_flags |= TSF_DIDRUN; 1256 1257 KASSERT(ts->ts_thread->td_flags & TDF_INMEM, 1258 ("sched_choose: thread swapped out")); 1259 return (ts->ts_thread); 1260 } 1261 return (PCPU_GET(idlethread)); 1262 } 1263 1264 void 1265 sched_userret(struct thread *td) 1266 { 1267 /* 1268 * XXX we cheat slightly on the locking here to avoid locking in 1269 * the usual case. Setting td_priority here is essentially an 1270 * incomplete workaround for not setting it properly elsewhere. 1271 * Now that some interrupt handlers are threads, not setting it 1272 * properly elsewhere can clobber it in the window between setting 1273 * it here and returning to user mode, so don't waste time setting 1274 * it perfectly here. 1275 */ 1276 KASSERT((td->td_flags & TDF_BORROWING) == 0, 1277 ("thread with borrowed priority returning to userland")); 1278 if (td->td_priority != td->td_user_pri) { 1279 thread_lock(td); 1280 td->td_priority = td->td_user_pri; 1281 td->td_base_pri = td->td_user_pri; 1282 thread_unlock(td); 1283 } 1284 } 1285 1286 void 1287 sched_bind(struct thread *td, int cpu) 1288 { 1289 struct td_sched *ts; 1290 1291 THREAD_LOCK_ASSERT(td, MA_OWNED); 1292 KASSERT(TD_IS_RUNNING(td), 1293 ("sched_bind: cannot bind non-running thread")); 1294 1295 ts = td->td_sched; 1296 1297 ts->ts_flags |= TSF_BOUND; 1298 #ifdef SMP 1299 ts->ts_runq = &runq_pcpu[cpu]; 1300 if (PCPU_GET(cpuid) == cpu) 1301 return; 1302 1303 mi_switch(SW_VOL, NULL); 1304 #endif 1305 } 1306 1307 void 1308 sched_unbind(struct thread* td) 1309 { 1310 THREAD_LOCK_ASSERT(td, MA_OWNED); 1311 td->td_sched->ts_flags &= ~TSF_BOUND; 1312 } 1313 1314 int 1315 sched_is_bound(struct thread *td) 1316 { 1317 THREAD_LOCK_ASSERT(td, MA_OWNED); 1318 return (td->td_sched->ts_flags & TSF_BOUND); 1319 } 1320 1321 void 1322 sched_relinquish(struct thread *td) 1323 { 1324 thread_lock(td); 1325 SCHED_STAT_INC(switch_relinquish); 1326 mi_switch(SW_VOL, NULL); 1327 thread_unlock(td); 1328 } 1329 1330 int 1331 sched_load(void) 1332 { 1333 return (sched_tdcnt); 1334 } 1335 1336 int 1337 sched_sizeof_proc(void) 1338 { 1339 return (sizeof(struct proc)); 1340 } 1341 1342 int 1343 sched_sizeof_thread(void) 1344 { 1345 return (sizeof(struct thread) + sizeof(struct td_sched)); 1346 } 1347 1348 fixpt_t 1349 sched_pctcpu(struct thread *td) 1350 { 1351 struct td_sched *ts; 1352 1353 ts = td->td_sched; 1354 return (ts->ts_pctcpu); 1355 } 1356 1357 void 1358 sched_tick(void) 1359 { 1360 } 1361 1362 /* 1363 * The actual idle process. 1364 */ 1365 void 1366 sched_idletd(void *dummy) 1367 { 1368 struct proc *p; 1369 struct thread *td; 1370 1371 td = curthread; 1372 p = td->td_proc; 1373 for (;;) { 1374 mtx_assert(&Giant, MA_NOTOWNED); 1375 1376 while (sched_runnable() == 0) 1377 cpu_idle(); 1378 1379 mtx_lock_spin(&sched_lock); 1380 mi_switch(SW_VOL, NULL); 1381 mtx_unlock_spin(&sched_lock); 1382 } 1383 } 1384 1385 /* 1386 * A CPU is entering for the first time or a thread is exiting. 1387 */ 1388 void 1389 sched_throw(struct thread *td) 1390 { 1391 /* 1392 * Correct spinlock nesting. The idle thread context that we are 1393 * borrowing was created so that it would start out with a single 1394 * spin lock (sched_lock) held in fork_trampoline(). Since we've 1395 * explicitly acquired locks in this function, the nesting count 1396 * is now 2 rather than 1. Since we are nested, calling 1397 * spinlock_exit() will simply adjust the counts without allowing 1398 * spin lock using code to interrupt us. 1399 */ 1400 if (td == NULL) { 1401 mtx_lock_spin(&sched_lock); 1402 spinlock_exit(); 1403 } else { 1404 MPASS(td->td_lock == &sched_lock); 1405 } 1406 mtx_assert(&sched_lock, MA_OWNED); 1407 KASSERT(curthread->td_md.md_spinlock_count == 1, ("invalid count")); 1408 PCPU_SET(switchtime, cpu_ticks()); 1409 PCPU_SET(switchticks, ticks); 1410 cpu_throw(td, choosethread()); /* doesn't return */ 1411 } 1412 1413 void 1414 sched_fork_exit(struct thread *td) 1415 { 1416 1417 /* 1418 * Finish setting up thread glue so that it begins execution in a 1419 * non-nested critical section with sched_lock held but not recursed. 1420 */ 1421 td->td_oncpu = PCPU_GET(cpuid); 1422 sched_lock.mtx_lock = (uintptr_t)td; 1423 THREAD_LOCK_ASSERT(td, MA_OWNED | MA_NOTRECURSED); 1424 } 1425 1426 #define KERN_SWITCH_INCLUDE 1 1427 #include "kern/kern_switch.c"
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