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 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/sdt.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_slice; /* Remaining part of time slice. */ 97 int ts_flags; 98 struct runq *ts_runq; /* runq the thread is currently on */ 99 #ifdef KTR 100 char ts_name[TS_NAME_LEN]; 101 #endif 102 }; 103 104 /* flags kept in td_flags */ 105 #define TDF_DIDRUN TDF_SCHED0 /* thread actually ran. */ 106 #define TDF_BOUND TDF_SCHED1 /* Bound to one CPU. */ 107 #define TDF_SLICEEND TDF_SCHED2 /* Thread time slice is over. */ 108 109 /* flags kept in ts_flags */ 110 #define TSF_AFFINITY 0x0001 /* Has a non-"full" CPU set. */ 111 112 #define SKE_RUNQ_PCPU(ts) \ 113 ((ts)->ts_runq != 0 && (ts)->ts_runq != &runq) 114 115 #define THREAD_CAN_SCHED(td, cpu) \ 116 CPU_ISSET((cpu), &(td)->td_cpuset->cs_mask) 117 118 static struct td_sched td_sched0; 119 static struct mtx sched_lock; 120 121 static int realstathz = 127; /* stathz is sometimes 0 and run off of hz. */ 122 static int sched_tdcnt; /* Total runnable threads in the system. */ 123 static int sched_slice = 12; /* Thread run time before rescheduling. */ 124 125 static void setup_runqs(void); 126 static void schedcpu(void); 127 static void schedcpu_thread(void); 128 static void sched_priority(struct thread *td, u_char prio); 129 static void sched_setup(void *dummy); 130 static void maybe_resched(struct thread *td); 131 static void updatepri(struct thread *td); 132 static void resetpriority(struct thread *td); 133 static void resetpriority_thread(struct thread *td); 134 #ifdef SMP 135 static int sched_pickcpu(struct thread *td); 136 static int forward_wakeup(int cpunum); 137 static void kick_other_cpu(int pri, int cpuid); 138 #endif 139 140 static struct kproc_desc sched_kp = { 141 "schedcpu", 142 schedcpu_thread, 143 NULL 144 }; 145 SYSINIT(schedcpu, SI_SUB_LAST, SI_ORDER_FIRST, kproc_start, 146 &sched_kp); 147 SYSINIT(sched_setup, SI_SUB_RUN_QUEUE, SI_ORDER_FIRST, sched_setup, NULL); 148 149 static void sched_initticks(void *dummy); 150 SYSINIT(sched_initticks, SI_SUB_CLOCKS, SI_ORDER_THIRD, sched_initticks, 151 NULL); 152 153 /* 154 * Global run queue. 155 */ 156 static struct runq runq; 157 158 #ifdef SMP 159 /* 160 * Per-CPU run queues 161 */ 162 static struct runq runq_pcpu[MAXCPU]; 163 long runq_length[MAXCPU]; 164 165 static cpuset_t idle_cpus_mask; 166 #endif 167 168 struct pcpuidlestat { 169 u_int idlecalls; 170 u_int oldidlecalls; 171 }; 172 static DPCPU_DEFINE(struct pcpuidlestat, idlestat); 173 174 static void 175 setup_runqs(void) 176 { 177 #ifdef SMP 178 int i; 179 180 for (i = 0; i < MAXCPU; ++i) 181 runq_init(&runq_pcpu[i]); 182 #endif 183 184 runq_init(&runq); 185 } 186 187 static int 188 sysctl_kern_quantum(SYSCTL_HANDLER_ARGS) 189 { 190 int error, new_val, period; 191 192 period = 1000000 / realstathz; 193 new_val = period * sched_slice; 194 error = sysctl_handle_int(oidp, &new_val, 0, req); 195 if (error != 0 || req->newptr == NULL) 196 return (error); 197 if (new_val <= 0) 198 return (EINVAL); 199 sched_slice = imax(1, (new_val + period / 2) / period); 200 hogticks = imax(1, (2 * hz * sched_slice + realstathz / 2) / 201 realstathz); 202 return (0); 203 } 204 205 SYSCTL_NODE(_kern, OID_AUTO, sched, CTLFLAG_RD, 0, "Scheduler"); 206 207 SYSCTL_STRING(_kern_sched, OID_AUTO, name, CTLFLAG_RD, "4BSD", 0, 208 "Scheduler name"); 209 SYSCTL_PROC(_kern_sched, OID_AUTO, quantum, CTLTYPE_INT | CTLFLAG_RW, 210 NULL, 0, sysctl_kern_quantum, "I", 211 "Quantum for timeshare threads in microseconds"); 212 SYSCTL_INT(_kern_sched, OID_AUTO, slice, CTLFLAG_RW, &sched_slice, 0, 213 "Quantum for timeshare threads in stathz ticks"); 214 #ifdef SMP 215 /* Enable forwarding of wakeups to all other cpus */ 216 static SYSCTL_NODE(_kern_sched, OID_AUTO, ipiwakeup, CTLFLAG_RD, NULL, 217 "Kernel SMP"); 218 219 static int runq_fuzz = 1; 220 SYSCTL_INT(_kern_sched, OID_AUTO, runq_fuzz, CTLFLAG_RW, &runq_fuzz, 0, ""); 221 222 static int forward_wakeup_enabled = 1; 223 SYSCTL_INT(_kern_sched_ipiwakeup, OID_AUTO, enabled, CTLFLAG_RW, 224 &forward_wakeup_enabled, 0, 225 "Forwarding of wakeup to idle CPUs"); 226 227 static int forward_wakeups_requested = 0; 228 SYSCTL_INT(_kern_sched_ipiwakeup, OID_AUTO, requested, CTLFLAG_RD, 229 &forward_wakeups_requested, 0, 230 "Requests for Forwarding of wakeup to idle CPUs"); 231 232 static int forward_wakeups_delivered = 0; 233 SYSCTL_INT(_kern_sched_ipiwakeup, OID_AUTO, delivered, CTLFLAG_RD, 234 &forward_wakeups_delivered, 0, 235 "Completed Forwarding of wakeup to idle CPUs"); 236 237 static int forward_wakeup_use_mask = 1; 238 SYSCTL_INT(_kern_sched_ipiwakeup, OID_AUTO, usemask, CTLFLAG_RW, 239 &forward_wakeup_use_mask, 0, 240 "Use the mask of idle cpus"); 241 242 static int forward_wakeup_use_loop = 0; 243 SYSCTL_INT(_kern_sched_ipiwakeup, OID_AUTO, useloop, CTLFLAG_RW, 244 &forward_wakeup_use_loop, 0, 245 "Use a loop to find idle cpus"); 246 247 #endif 248 #if 0 249 static int sched_followon = 0; 250 SYSCTL_INT(_kern_sched, OID_AUTO, followon, CTLFLAG_RW, 251 &sched_followon, 0, 252 "allow threads to share a quantum"); 253 #endif 254 255 SDT_PROVIDER_DEFINE(sched); 256 257 SDT_PROBE_DEFINE3(sched, , , change__pri, "struct thread *", 258 "struct proc *", "uint8_t"); 259 SDT_PROBE_DEFINE3(sched, , , dequeue, "struct thread *", 260 "struct proc *", "void *"); 261 SDT_PROBE_DEFINE4(sched, , , enqueue, "struct thread *", 262 "struct proc *", "void *", "int"); 263 SDT_PROBE_DEFINE4(sched, , , lend__pri, "struct thread *", 264 "struct proc *", "uint8_t", "struct thread *"); 265 SDT_PROBE_DEFINE2(sched, , , load__change, "int", "int"); 266 SDT_PROBE_DEFINE2(sched, , , off__cpu, "struct thread *", 267 "struct proc *"); 268 SDT_PROBE_DEFINE(sched, , , on__cpu); 269 SDT_PROBE_DEFINE(sched, , , remain__cpu); 270 SDT_PROBE_DEFINE2(sched, , , surrender, "struct thread *", 271 "struct proc *"); 272 273 static __inline void 274 sched_load_add(void) 275 { 276 277 sched_tdcnt++; 278 KTR_COUNTER0(KTR_SCHED, "load", "global load", sched_tdcnt); 279 SDT_PROBE2(sched, , , load__change, NOCPU, sched_tdcnt); 280 } 281 282 static __inline void 283 sched_load_rem(void) 284 { 285 286 sched_tdcnt--; 287 KTR_COUNTER0(KTR_SCHED, "load", "global load", sched_tdcnt); 288 SDT_PROBE2(sched, , , load__change, NOCPU, sched_tdcnt); 289 } 290 /* 291 * Arrange to reschedule if necessary, taking the priorities and 292 * schedulers into account. 293 */ 294 static void 295 maybe_resched(struct thread *td) 296 { 297 298 THREAD_LOCK_ASSERT(td, MA_OWNED); 299 if (td->td_priority < curthread->td_priority) 300 curthread->td_flags |= TDF_NEEDRESCHED; 301 } 302 303 /* 304 * This function is called when a thread is about to be put on run queue 305 * because it has been made runnable or its priority has been adjusted. It 306 * determines if the new thread should be immediately preempted to. If so, 307 * it switches to it and eventually returns true. If not, it returns false 308 * so that the caller may place the thread on an appropriate run queue. 309 */ 310 int 311 maybe_preempt(struct thread *td) 312 { 313 #ifdef PREEMPTION 314 struct thread *ctd; 315 int cpri, pri; 316 317 /* 318 * The new thread should not preempt the current thread if any of the 319 * following conditions are true: 320 * 321 * - The kernel is in the throes of crashing (panicstr). 322 * - The current thread has a higher (numerically lower) or 323 * equivalent priority. Note that this prevents curthread from 324 * trying to preempt to itself. 325 * - It is too early in the boot for context switches (cold is set). 326 * - The current thread has an inhibitor set or is in the process of 327 * exiting. In this case, the current thread is about to switch 328 * out anyways, so there's no point in preempting. If we did, 329 * the current thread would not be properly resumed as well, so 330 * just avoid that whole landmine. 331 * - If the new thread's priority is not a realtime priority and 332 * the current thread's priority is not an idle priority and 333 * FULL_PREEMPTION is disabled. 334 * 335 * If all of these conditions are false, but the current thread is in 336 * a nested critical section, then we have to defer the preemption 337 * until we exit the critical section. Otherwise, switch immediately 338 * to the new thread. 339 */ 340 ctd = curthread; 341 THREAD_LOCK_ASSERT(td, MA_OWNED); 342 KASSERT((td->td_inhibitors == 0), 343 ("maybe_preempt: trying to run inhibited thread")); 344 pri = td->td_priority; 345 cpri = ctd->td_priority; 346 if (panicstr != NULL || pri >= cpri || cold /* || dumping */ || 347 TD_IS_INHIBITED(ctd)) 348 return (0); 349 #ifndef FULL_PREEMPTION 350 if (pri > PRI_MAX_ITHD && cpri < PRI_MIN_IDLE) 351 return (0); 352 #endif 353 354 if (ctd->td_critnest > 1) { 355 CTR1(KTR_PROC, "maybe_preempt: in critical section %d", 356 ctd->td_critnest); 357 ctd->td_owepreempt = 1; 358 return (0); 359 } 360 /* 361 * Thread is runnable but not yet put on system run queue. 362 */ 363 MPASS(ctd->td_lock == td->td_lock); 364 MPASS(TD_ON_RUNQ(td)); 365 TD_SET_RUNNING(td); 366 CTR3(KTR_PROC, "preempting to thread %p (pid %d, %s)\n", td, 367 td->td_proc->p_pid, td->td_name); 368 mi_switch(SW_INVOL | SW_PREEMPT | SWT_PREEMPT, td); 369 /* 370 * td's lock pointer may have changed. We have to return with it 371 * locked. 372 */ 373 spinlock_enter(); 374 thread_unlock(ctd); 375 thread_lock(td); 376 spinlock_exit(); 377 return (1); 378 #else 379 return (0); 380 #endif 381 } 382 383 /* 384 * Constants for digital decay and forget: 385 * 90% of (td_estcpu) usage in 5 * loadav time 386 * 95% of (ts_pctcpu) usage in 60 seconds (load insensitive) 387 * Note that, as ps(1) mentions, this can let percentages 388 * total over 100% (I've seen 137.9% for 3 processes). 389 * 390 * Note that schedclock() updates td_estcpu and p_cpticks asynchronously. 391 * 392 * We wish to decay away 90% of td_estcpu in (5 * loadavg) seconds. 393 * That is, the system wants to compute a value of decay such 394 * that the following for loop: 395 * for (i = 0; i < (5 * loadavg); i++) 396 * td_estcpu *= decay; 397 * will compute 398 * td_estcpu *= 0.1; 399 * for all values of loadavg: 400 * 401 * Mathematically this loop can be expressed by saying: 402 * decay ** (5 * loadavg) ~= .1 403 * 404 * The system computes decay as: 405 * decay = (2 * loadavg) / (2 * loadavg + 1) 406 * 407 * We wish to prove that the system's computation of decay 408 * will always fulfill the equation: 409 * decay ** (5 * loadavg) ~= .1 410 * 411 * If we compute b as: 412 * b = 2 * loadavg 413 * then 414 * decay = b / (b + 1) 415 * 416 * We now need to prove two things: 417 * 1) Given factor ** (5 * loadavg) ~= .1, prove factor == b/(b+1) 418 * 2) Given b/(b+1) ** power ~= .1, prove power == (5 * loadavg) 419 * 420 * Facts: 421 * For x close to zero, exp(x) =~ 1 + x, since 422 * exp(x) = 0! + x**1/1! + x**2/2! + ... . 423 * therefore exp(-1/b) =~ 1 - (1/b) = (b-1)/b. 424 * For x close to zero, ln(1+x) =~ x, since 425 * ln(1+x) = x - x**2/2 + x**3/3 - ... -1 < x < 1 426 * therefore ln(b/(b+1)) = ln(1 - 1/(b+1)) =~ -1/(b+1). 427 * ln(.1) =~ -2.30 428 * 429 * Proof of (1): 430 * Solve (factor)**(power) =~ .1 given power (5*loadav): 431 * solving for factor, 432 * ln(factor) =~ (-2.30/5*loadav), or 433 * factor =~ exp(-1/((5/2.30)*loadav)) =~ exp(-1/(2*loadav)) = 434 * exp(-1/b) =~ (b-1)/b =~ b/(b+1). QED 435 * 436 * Proof of (2): 437 * Solve (factor)**(power) =~ .1 given factor == (b/(b+1)): 438 * solving for power, 439 * power*ln(b/(b+1)) =~ -2.30, or 440 * power =~ 2.3 * (b + 1) = 4.6*loadav + 2.3 =~ 5*loadav. QED 441 * 442 * Actual power values for the implemented algorithm are as follows: 443 * loadav: 1 2 3 4 444 * power: 5.68 10.32 14.94 19.55 445 */ 446 447 /* calculations for digital decay to forget 90% of usage in 5*loadav sec */ 448 #define loadfactor(loadav) (2 * (loadav)) 449 #define decay_cpu(loadfac, cpu) (((loadfac) * (cpu)) / ((loadfac) + FSCALE)) 450 451 /* decay 95% of `ts_pctcpu' in 60 seconds; see CCPU_SHIFT before changing */ 452 static fixpt_t ccpu = 0.95122942450071400909 * FSCALE; /* exp(-1/20) */ 453 SYSCTL_UINT(_kern, OID_AUTO, ccpu, CTLFLAG_RD, &ccpu, 0, ""); 454 455 /* 456 * If `ccpu' is not equal to `exp(-1/20)' and you still want to use the 457 * faster/more-accurate formula, you'll have to estimate CCPU_SHIFT below 458 * and possibly adjust FSHIFT in "param.h" so that (FSHIFT >= CCPU_SHIFT). 459 * 460 * To estimate CCPU_SHIFT for exp(-1/20), the following formula was used: 461 * 1 - exp(-1/20) ~= 0.0487 ~= 0.0488 == 1 (fixed pt, *11* bits). 462 * 463 * If you don't want to bother with the faster/more-accurate formula, you 464 * can set CCPU_SHIFT to (FSHIFT + 1) which will use a slower/less-accurate 465 * (more general) method of calculating the %age of CPU used by a process. 466 */ 467 #define CCPU_SHIFT 11 468 469 /* 470 * Recompute process priorities, every hz ticks. 471 * MP-safe, called without the Giant mutex. 472 */ 473 /* ARGSUSED */ 474 static void 475 schedcpu(void) 476 { 477 register fixpt_t loadfac = loadfactor(averunnable.ldavg[0]); 478 struct thread *td; 479 struct proc *p; 480 struct td_sched *ts; 481 int awake; 482 483 sx_slock(&allproc_lock); 484 FOREACH_PROC_IN_SYSTEM(p) { 485 PROC_LOCK(p); 486 if (p->p_state == PRS_NEW) { 487 PROC_UNLOCK(p); 488 continue; 489 } 490 FOREACH_THREAD_IN_PROC(p, td) { 491 awake = 0; 492 thread_lock(td); 493 ts = td->td_sched; 494 /* 495 * Increment sleep time (if sleeping). We 496 * ignore overflow, as above. 497 */ 498 /* 499 * The td_sched slptimes are not touched in wakeup 500 * because the thread may not HAVE everything in 501 * memory? XXX I think this is out of date. 502 */ 503 if (TD_ON_RUNQ(td)) { 504 awake = 1; 505 td->td_flags &= ~TDF_DIDRUN; 506 } else if (TD_IS_RUNNING(td)) { 507 awake = 1; 508 /* Do not clear TDF_DIDRUN */ 509 } else if (td->td_flags & TDF_DIDRUN) { 510 awake = 1; 511 td->td_flags &= ~TDF_DIDRUN; 512 } 513 514 /* 515 * ts_pctcpu is only for ps and ttyinfo(). 516 */ 517 ts->ts_pctcpu = (ts->ts_pctcpu * ccpu) >> FSHIFT; 518 /* 519 * If the td_sched has been idle the entire second, 520 * stop recalculating its priority until 521 * it wakes up. 522 */ 523 if (ts->ts_cpticks != 0) { 524 #if (FSHIFT >= CCPU_SHIFT) 525 ts->ts_pctcpu += (realstathz == 100) 526 ? ((fixpt_t) ts->ts_cpticks) << 527 (FSHIFT - CCPU_SHIFT) : 528 100 * (((fixpt_t) ts->ts_cpticks) 529 << (FSHIFT - CCPU_SHIFT)) / realstathz; 530 #else 531 ts->ts_pctcpu += ((FSCALE - ccpu) * 532 (ts->ts_cpticks * 533 FSCALE / realstathz)) >> FSHIFT; 534 #endif 535 ts->ts_cpticks = 0; 536 } 537 /* 538 * If there are ANY running threads in this process, 539 * then don't count it as sleeping. 540 * XXX: this is broken. 541 */ 542 if (awake) { 543 if (ts->ts_slptime > 1) { 544 /* 545 * In an ideal world, this should not 546 * happen, because whoever woke us 547 * up from the long sleep should have 548 * unwound the slptime and reset our 549 * priority before we run at the stale 550 * priority. Should KASSERT at some 551 * point when all the cases are fixed. 552 */ 553 updatepri(td); 554 } 555 ts->ts_slptime = 0; 556 } else 557 ts->ts_slptime++; 558 if (ts->ts_slptime > 1) { 559 thread_unlock(td); 560 continue; 561 } 562 td->td_estcpu = decay_cpu(loadfac, td->td_estcpu); 563 resetpriority(td); 564 resetpriority_thread(td); 565 thread_unlock(td); 566 } 567 PROC_UNLOCK(p); 568 } 569 sx_sunlock(&allproc_lock); 570 } 571 572 /* 573 * Main loop for a kthread that executes schedcpu once a second. 574 */ 575 static void 576 schedcpu_thread(void) 577 { 578 579 for (;;) { 580 schedcpu(); 581 pause("-", hz); 582 } 583 } 584 585 /* 586 * Recalculate the priority of a process after it has slept for a while. 587 * For all load averages >= 1 and max td_estcpu of 255, sleeping for at 588 * least six times the loadfactor will decay td_estcpu to zero. 589 */ 590 static void 591 updatepri(struct thread *td) 592 { 593 struct td_sched *ts; 594 fixpt_t loadfac; 595 unsigned int newcpu; 596 597 ts = td->td_sched; 598 loadfac = loadfactor(averunnable.ldavg[0]); 599 if (ts->ts_slptime > 5 * loadfac) 600 td->td_estcpu = 0; 601 else { 602 newcpu = td->td_estcpu; 603 ts->ts_slptime--; /* was incremented in schedcpu() */ 604 while (newcpu && --ts->ts_slptime) 605 newcpu = decay_cpu(loadfac, newcpu); 606 td->td_estcpu = newcpu; 607 } 608 } 609 610 /* 611 * Compute the priority of a process when running in user mode. 612 * Arrange to reschedule if the resulting priority is better 613 * than that of the current process. 614 */ 615 static void 616 resetpriority(struct thread *td) 617 { 618 register unsigned int newpriority; 619 620 if (td->td_pri_class == PRI_TIMESHARE) { 621 newpriority = PUSER + td->td_estcpu / INVERSE_ESTCPU_WEIGHT + 622 NICE_WEIGHT * (td->td_proc->p_nice - PRIO_MIN); 623 newpriority = min(max(newpriority, PRI_MIN_TIMESHARE), 624 PRI_MAX_TIMESHARE); 625 sched_user_prio(td, newpriority); 626 } 627 } 628 629 /* 630 * Update the thread's priority when the associated process's user 631 * priority changes. 632 */ 633 static void 634 resetpriority_thread(struct thread *td) 635 { 636 637 /* Only change threads with a time sharing user priority. */ 638 if (td->td_priority < PRI_MIN_TIMESHARE || 639 td->td_priority > PRI_MAX_TIMESHARE) 640 return; 641 642 /* XXX the whole needresched thing is broken, but not silly. */ 643 maybe_resched(td); 644 645 sched_prio(td, td->td_user_pri); 646 } 647 648 /* ARGSUSED */ 649 static void 650 sched_setup(void *dummy) 651 { 652 653 setup_runqs(); 654 655 /* Account for thread0. */ 656 sched_load_add(); 657 } 658 659 /* 660 * This routine determines time constants after stathz and hz are setup. 661 */ 662 static void 663 sched_initticks(void *dummy) 664 { 665 666 realstathz = stathz ? stathz : hz; 667 sched_slice = realstathz / 10; /* ~100ms */ 668 hogticks = imax(1, (2 * hz * sched_slice + realstathz / 2) / 669 realstathz); 670 } 671 672 /* External interfaces start here */ 673 674 /* 675 * Very early in the boot some setup of scheduler-specific 676 * parts of proc0 and of some scheduler resources needs to be done. 677 * Called from: 678 * proc0_init() 679 */ 680 void 681 schedinit(void) 682 { 683 /* 684 * Set up the scheduler specific parts of proc0. 685 */ 686 proc0.p_sched = NULL; /* XXX */ 687 thread0.td_sched = &td_sched0; 688 thread0.td_lock = &sched_lock; 689 td_sched0.ts_slice = sched_slice; 690 mtx_init(&sched_lock, "sched lock", NULL, MTX_SPIN | MTX_RECURSE); 691 } 692 693 int 694 sched_runnable(void) 695 { 696 #ifdef SMP 697 return runq_check(&runq) + runq_check(&runq_pcpu[PCPU_GET(cpuid)]); 698 #else 699 return runq_check(&runq); 700 #endif 701 } 702 703 int 704 sched_rr_interval(void) 705 { 706 707 /* Convert sched_slice from stathz to hz. */ 708 return (imax(1, (sched_slice * hz + realstathz / 2) / realstathz)); 709 } 710 711 /* 712 * We adjust the priority of the current process. The priority of 713 * a process gets worse as it accumulates CPU time. The cpu usage 714 * estimator (td_estcpu) is increased here. resetpriority() will 715 * compute a different priority each time td_estcpu increases by 716 * INVERSE_ESTCPU_WEIGHT 717 * (until MAXPRI is reached). The cpu usage estimator ramps up 718 * quite quickly when the process is running (linearly), and decays 719 * away exponentially, at a rate which is proportionally slower when 720 * the system is busy. The basic principle is that the system will 721 * 90% forget that the process used a lot of CPU time in 5 * loadav 722 * seconds. This causes the system to favor processes which haven't 723 * run much recently, and to round-robin among other processes. 724 */ 725 void 726 sched_clock(struct thread *td) 727 { 728 struct pcpuidlestat *stat; 729 struct td_sched *ts; 730 731 THREAD_LOCK_ASSERT(td, MA_OWNED); 732 ts = td->td_sched; 733 734 ts->ts_cpticks++; 735 td->td_estcpu = ESTCPULIM(td->td_estcpu + 1); 736 if ((td->td_estcpu % INVERSE_ESTCPU_WEIGHT) == 0) { 737 resetpriority(td); 738 resetpriority_thread(td); 739 } 740 741 /* 742 * Force a context switch if the current thread has used up a full 743 * time slice (default is 100ms). 744 */ 745 if (!TD_IS_IDLETHREAD(td) && --ts->ts_slice <= 0) { 746 ts->ts_slice = sched_slice; 747 td->td_flags |= TDF_NEEDRESCHED | TDF_SLICEEND; 748 } 749 750 stat = DPCPU_PTR(idlestat); 751 stat->oldidlecalls = stat->idlecalls; 752 stat->idlecalls = 0; 753 } 754 755 /* 756 * Charge child's scheduling CPU usage to parent. 757 */ 758 void 759 sched_exit(struct proc *p, struct thread *td) 760 { 761 762 KTR_STATE1(KTR_SCHED, "thread", sched_tdname(td), "proc exit", 763 "prio:%d", td->td_priority); 764 765 PROC_LOCK_ASSERT(p, MA_OWNED); 766 sched_exit_thread(FIRST_THREAD_IN_PROC(p), td); 767 } 768 769 void 770 sched_exit_thread(struct thread *td, struct thread *child) 771 { 772 773 KTR_STATE1(KTR_SCHED, "thread", sched_tdname(child), "exit", 774 "prio:%d", child->td_priority); 775 thread_lock(td); 776 td->td_estcpu = ESTCPULIM(td->td_estcpu + child->td_estcpu); 777 thread_unlock(td); 778 thread_lock(child); 779 if ((child->td_flags & TDF_NOLOAD) == 0) 780 sched_load_rem(); 781 thread_unlock(child); 782 } 783 784 void 785 sched_fork(struct thread *td, struct thread *childtd) 786 { 787 sched_fork_thread(td, childtd); 788 } 789 790 void 791 sched_fork_thread(struct thread *td, struct thread *childtd) 792 { 793 struct td_sched *ts; 794 795 childtd->td_oncpu = NOCPU; 796 childtd->td_lastcpu = NOCPU; 797 childtd->td_estcpu = td->td_estcpu; 798 childtd->td_lock = &sched_lock; 799 childtd->td_cpuset = cpuset_ref(td->td_cpuset); 800 childtd->td_priority = childtd->td_base_pri; 801 ts = childtd->td_sched; 802 bzero(ts, sizeof(*ts)); 803 ts->ts_flags |= (td->td_sched->ts_flags & TSF_AFFINITY); 804 ts->ts_slice = 1; 805 } 806 807 void 808 sched_nice(struct proc *p, int nice) 809 { 810 struct thread *td; 811 812 PROC_LOCK_ASSERT(p, MA_OWNED); 813 p->p_nice = nice; 814 FOREACH_THREAD_IN_PROC(p, td) { 815 thread_lock(td); 816 resetpriority(td); 817 resetpriority_thread(td); 818 thread_unlock(td); 819 } 820 } 821 822 void 823 sched_class(struct thread *td, int class) 824 { 825 THREAD_LOCK_ASSERT(td, MA_OWNED); 826 td->td_pri_class = class; 827 } 828 829 /* 830 * Adjust the priority of a thread. 831 */ 832 static void 833 sched_priority(struct thread *td, u_char prio) 834 { 835 836 837 KTR_POINT3(KTR_SCHED, "thread", sched_tdname(td), "priority change", 838 "prio:%d", td->td_priority, "new prio:%d", prio, KTR_ATTR_LINKED, 839 sched_tdname(curthread)); 840 SDT_PROBE3(sched, , , change__pri, td, td->td_proc, prio); 841 if (td != curthread && prio > td->td_priority) { 842 KTR_POINT3(KTR_SCHED, "thread", sched_tdname(curthread), 843 "lend prio", "prio:%d", td->td_priority, "new prio:%d", 844 prio, KTR_ATTR_LINKED, sched_tdname(td)); 845 SDT_PROBE4(sched, , , lend__pri, td, td->td_proc, prio, 846 curthread); 847 } 848 THREAD_LOCK_ASSERT(td, MA_OWNED); 849 if (td->td_priority == prio) 850 return; 851 td->td_priority = prio; 852 if (TD_ON_RUNQ(td) && td->td_rqindex != (prio / RQ_PPQ)) { 853 sched_rem(td); 854 sched_add(td, SRQ_BORING); 855 } 856 } 857 858 /* 859 * Update a thread's priority when it is lent another thread's 860 * priority. 861 */ 862 void 863 sched_lend_prio(struct thread *td, u_char prio) 864 { 865 866 td->td_flags |= TDF_BORROWING; 867 sched_priority(td, prio); 868 } 869 870 /* 871 * Restore a thread's priority when priority propagation is 872 * over. The prio argument is the minimum priority the thread 873 * needs to have to satisfy other possible priority lending 874 * requests. If the thread's regulary priority is less 875 * important than prio the thread will keep a priority boost 876 * of prio. 877 */ 878 void 879 sched_unlend_prio(struct thread *td, u_char prio) 880 { 881 u_char base_pri; 882 883 if (td->td_base_pri >= PRI_MIN_TIMESHARE && 884 td->td_base_pri <= PRI_MAX_TIMESHARE) 885 base_pri = td->td_user_pri; 886 else 887 base_pri = td->td_base_pri; 888 if (prio >= base_pri) { 889 td->td_flags &= ~TDF_BORROWING; 890 sched_prio(td, base_pri); 891 } else 892 sched_lend_prio(td, prio); 893 } 894 895 void 896 sched_prio(struct thread *td, u_char prio) 897 { 898 u_char oldprio; 899 900 /* First, update the base priority. */ 901 td->td_base_pri = prio; 902 903 /* 904 * If the thread is borrowing another thread's priority, don't ever 905 * lower the priority. 906 */ 907 if (td->td_flags & TDF_BORROWING && td->td_priority < prio) 908 return; 909 910 /* Change the real priority. */ 911 oldprio = td->td_priority; 912 sched_priority(td, prio); 913 914 /* 915 * If the thread is on a turnstile, then let the turnstile update 916 * its state. 917 */ 918 if (TD_ON_LOCK(td) && oldprio != prio) 919 turnstile_adjust(td, oldprio); 920 } 921 922 void 923 sched_user_prio(struct thread *td, u_char prio) 924 { 925 926 THREAD_LOCK_ASSERT(td, MA_OWNED); 927 td->td_base_user_pri = prio; 928 if (td->td_lend_user_pri <= prio) 929 return; 930 td->td_user_pri = prio; 931 } 932 933 void 934 sched_lend_user_prio(struct thread *td, u_char prio) 935 { 936 937 THREAD_LOCK_ASSERT(td, MA_OWNED); 938 td->td_lend_user_pri = prio; 939 td->td_user_pri = min(prio, td->td_base_user_pri); 940 if (td->td_priority > td->td_user_pri) 941 sched_prio(td, td->td_user_pri); 942 else if (td->td_priority != td->td_user_pri) 943 td->td_flags |= TDF_NEEDRESCHED; 944 } 945 946 void 947 sched_sleep(struct thread *td, int pri) 948 { 949 950 THREAD_LOCK_ASSERT(td, MA_OWNED); 951 td->td_slptick = ticks; 952 td->td_sched->ts_slptime = 0; 953 if (pri != 0 && PRI_BASE(td->td_pri_class) == PRI_TIMESHARE) 954 sched_prio(td, pri); 955 if (TD_IS_SUSPENDED(td) || pri >= PSOCK) 956 td->td_flags |= TDF_CANSWAP; 957 } 958 959 void 960 sched_switch(struct thread *td, struct thread *newtd, int flags) 961 { 962 struct mtx *tmtx; 963 struct td_sched *ts; 964 struct proc *p; 965 int preempted; 966 967 tmtx = NULL; 968 ts = td->td_sched; 969 p = td->td_proc; 970 971 THREAD_LOCK_ASSERT(td, MA_OWNED); 972 973 /* 974 * Switch to the sched lock to fix things up and pick 975 * a new thread. 976 * Block the td_lock in order to avoid breaking the critical path. 977 */ 978 if (td->td_lock != &sched_lock) { 979 mtx_lock_spin(&sched_lock); 980 tmtx = thread_lock_block(td); 981 } 982 983 if ((td->td_flags & TDF_NOLOAD) == 0) 984 sched_load_rem(); 985 986 td->td_lastcpu = td->td_oncpu; 987 preempted = !((td->td_flags & TDF_SLICEEND) || 988 (flags & SWT_RELINQUISH)); 989 td->td_flags &= ~(TDF_NEEDRESCHED | TDF_SLICEEND); 990 td->td_owepreempt = 0; 991 td->td_oncpu = NOCPU; 992 993 /* 994 * At the last moment, if this thread is still marked RUNNING, 995 * then put it back on the run queue as it has not been suspended 996 * or stopped or any thing else similar. We never put the idle 997 * threads on the run queue, however. 998 */ 999 if (td->td_flags & TDF_IDLETD) { 1000 TD_SET_CAN_RUN(td); 1001 #ifdef SMP 1002 CPU_CLR(PCPU_GET(cpuid), &idle_cpus_mask); 1003 #endif 1004 } else { 1005 if (TD_IS_RUNNING(td)) { 1006 /* Put us back on the run queue. */ 1007 sched_add(td, preempted ? 1008 SRQ_OURSELF|SRQ_YIELDING|SRQ_PREEMPTED : 1009 SRQ_OURSELF|SRQ_YIELDING); 1010 } 1011 } 1012 if (newtd) { 1013 /* 1014 * The thread we are about to run needs to be counted 1015 * as if it had been added to the run queue and selected. 1016 * It came from: 1017 * * A preemption 1018 * * An upcall 1019 * * A followon 1020 */ 1021 KASSERT((newtd->td_inhibitors == 0), 1022 ("trying to run inhibited thread")); 1023 newtd->td_flags |= TDF_DIDRUN; 1024 TD_SET_RUNNING(newtd); 1025 if ((newtd->td_flags & TDF_NOLOAD) == 0) 1026 sched_load_add(); 1027 } else { 1028 newtd = choosethread(); 1029 MPASS(newtd->td_lock == &sched_lock); 1030 } 1031 1032 if (td != newtd) { 1033 #ifdef HWPMC_HOOKS 1034 if (PMC_PROC_IS_USING_PMCS(td->td_proc)) 1035 PMC_SWITCH_CONTEXT(td, PMC_FN_CSW_OUT); 1036 #endif 1037 1038 SDT_PROBE2(sched, , , off__cpu, newtd, newtd->td_proc); 1039 1040 /* I feel sleepy */ 1041 lock_profile_release_lock(&sched_lock.lock_object); 1042 #ifdef KDTRACE_HOOKS 1043 /* 1044 * If DTrace has set the active vtime enum to anything 1045 * other than INACTIVE (0), then it should have set the 1046 * function to call. 1047 */ 1048 if (dtrace_vtime_active) 1049 (*dtrace_vtime_switch_func)(newtd); 1050 #endif 1051 1052 cpu_switch(td, newtd, tmtx != NULL ? tmtx : td->td_lock); 1053 lock_profile_obtain_lock_success(&sched_lock.lock_object, 1054 0, 0, __FILE__, __LINE__); 1055 /* 1056 * Where am I? What year is it? 1057 * We are in the same thread that went to sleep above, 1058 * but any amount of time may have passed. All our context 1059 * will still be available as will local variables. 1060 * PCPU values however may have changed as we may have 1061 * changed CPU so don't trust cached values of them. 1062 * New threads will go to fork_exit() instead of here 1063 * so if you change things here you may need to change 1064 * things there too. 1065 * 1066 * If the thread above was exiting it will never wake 1067 * up again here, so either it has saved everything it 1068 * needed to, or the thread_wait() or wait() will 1069 * need to reap it. 1070 */ 1071 1072 SDT_PROBE0(sched, , , on__cpu); 1073 #ifdef HWPMC_HOOKS 1074 if (PMC_PROC_IS_USING_PMCS(td->td_proc)) 1075 PMC_SWITCH_CONTEXT(td, PMC_FN_CSW_IN); 1076 #endif 1077 } else 1078 SDT_PROBE0(sched, , , remain__cpu); 1079 1080 #ifdef SMP 1081 if (td->td_flags & TDF_IDLETD) 1082 CPU_SET(PCPU_GET(cpuid), &idle_cpus_mask); 1083 #endif 1084 sched_lock.mtx_lock = (uintptr_t)td; 1085 td->td_oncpu = PCPU_GET(cpuid); 1086 MPASS(td->td_lock == &sched_lock); 1087 } 1088 1089 void 1090 sched_wakeup(struct thread *td) 1091 { 1092 struct td_sched *ts; 1093 1094 THREAD_LOCK_ASSERT(td, MA_OWNED); 1095 ts = td->td_sched; 1096 td->td_flags &= ~TDF_CANSWAP; 1097 if (ts->ts_slptime > 1) { 1098 updatepri(td); 1099 resetpriority(td); 1100 } 1101 td->td_slptick = 0; 1102 ts->ts_slptime = 0; 1103 ts->ts_slice = sched_slice; 1104 sched_add(td, SRQ_BORING); 1105 } 1106 1107 #ifdef SMP 1108 static int 1109 forward_wakeup(int cpunum) 1110 { 1111 struct pcpu *pc; 1112 cpuset_t dontuse, map, map2; 1113 u_int id, me; 1114 int iscpuset; 1115 1116 mtx_assert(&sched_lock, MA_OWNED); 1117 1118 CTR0(KTR_RUNQ, "forward_wakeup()"); 1119 1120 if ((!forward_wakeup_enabled) || 1121 (forward_wakeup_use_mask == 0 && forward_wakeup_use_loop == 0)) 1122 return (0); 1123 if (!smp_started || cold || panicstr) 1124 return (0); 1125 1126 forward_wakeups_requested++; 1127 1128 /* 1129 * Check the idle mask we received against what we calculated 1130 * before in the old version. 1131 */ 1132 me = PCPU_GET(cpuid); 1133 1134 /* Don't bother if we should be doing it ourself. */ 1135 if (CPU_ISSET(me, &idle_cpus_mask) && 1136 (cpunum == NOCPU || me == cpunum)) 1137 return (0); 1138 1139 CPU_SETOF(me, &dontuse); 1140 CPU_OR(&dontuse, &stopped_cpus); 1141 CPU_OR(&dontuse, &hlt_cpus_mask); 1142 CPU_ZERO(&map2); 1143 if (forward_wakeup_use_loop) { 1144 STAILQ_FOREACH(pc, &cpuhead, pc_allcpu) { 1145 id = pc->pc_cpuid; 1146 if (!CPU_ISSET(id, &dontuse) && 1147 pc->pc_curthread == pc->pc_idlethread) { 1148 CPU_SET(id, &map2); 1149 } 1150 } 1151 } 1152 1153 if (forward_wakeup_use_mask) { 1154 map = idle_cpus_mask; 1155 CPU_NAND(&map, &dontuse); 1156 1157 /* If they are both on, compare and use loop if different. */ 1158 if (forward_wakeup_use_loop) { 1159 if (CPU_CMP(&map, &map2)) { 1160 printf("map != map2, loop method preferred\n"); 1161 map = map2; 1162 } 1163 } 1164 } else { 1165 map = map2; 1166 } 1167 1168 /* If we only allow a specific CPU, then mask off all the others. */ 1169 if (cpunum != NOCPU) { 1170 KASSERT((cpunum <= mp_maxcpus),("forward_wakeup: bad cpunum.")); 1171 iscpuset = CPU_ISSET(cpunum, &map); 1172 if (iscpuset == 0) 1173 CPU_ZERO(&map); 1174 else 1175 CPU_SETOF(cpunum, &map); 1176 } 1177 if (!CPU_EMPTY(&map)) { 1178 forward_wakeups_delivered++; 1179 STAILQ_FOREACH(pc, &cpuhead, pc_allcpu) { 1180 id = pc->pc_cpuid; 1181 if (!CPU_ISSET(id, &map)) 1182 continue; 1183 if (cpu_idle_wakeup(pc->pc_cpuid)) 1184 CPU_CLR(id, &map); 1185 } 1186 if (!CPU_EMPTY(&map)) 1187 ipi_selected(map, IPI_AST); 1188 return (1); 1189 } 1190 if (cpunum == NOCPU) 1191 printf("forward_wakeup: Idle processor not found\n"); 1192 return (0); 1193 } 1194 1195 static void 1196 kick_other_cpu(int pri, int cpuid) 1197 { 1198 struct pcpu *pcpu; 1199 int cpri; 1200 1201 pcpu = pcpu_find(cpuid); 1202 if (CPU_ISSET(cpuid, &idle_cpus_mask)) { 1203 forward_wakeups_delivered++; 1204 if (!cpu_idle_wakeup(cpuid)) 1205 ipi_cpu(cpuid, IPI_AST); 1206 return; 1207 } 1208 1209 cpri = pcpu->pc_curthread->td_priority; 1210 if (pri >= cpri) 1211 return; 1212 1213 #if defined(IPI_PREEMPTION) && defined(PREEMPTION) 1214 #if !defined(FULL_PREEMPTION) 1215 if (pri <= PRI_MAX_ITHD) 1216 #endif /* ! FULL_PREEMPTION */ 1217 { 1218 ipi_cpu(cpuid, IPI_PREEMPT); 1219 return; 1220 } 1221 #endif /* defined(IPI_PREEMPTION) && defined(PREEMPTION) */ 1222 1223 pcpu->pc_curthread->td_flags |= TDF_NEEDRESCHED; 1224 ipi_cpu(cpuid, IPI_AST); 1225 return; 1226 } 1227 #endif /* SMP */ 1228 1229 #ifdef SMP 1230 static int 1231 sched_pickcpu(struct thread *td) 1232 { 1233 int best, cpu; 1234 1235 mtx_assert(&sched_lock, MA_OWNED); 1236 1237 if (THREAD_CAN_SCHED(td, td->td_lastcpu)) 1238 best = td->td_lastcpu; 1239 else 1240 best = NOCPU; 1241 CPU_FOREACH(cpu) { 1242 if (!THREAD_CAN_SCHED(td, cpu)) 1243 continue; 1244 1245 if (best == NOCPU) 1246 best = cpu; 1247 else if (runq_length[cpu] < runq_length[best]) 1248 best = cpu; 1249 } 1250 KASSERT(best != NOCPU, ("no valid CPUs")); 1251 1252 return (best); 1253 } 1254 #endif 1255 1256 void 1257 sched_add(struct thread *td, int flags) 1258 #ifdef SMP 1259 { 1260 cpuset_t tidlemsk; 1261 struct td_sched *ts; 1262 u_int cpu, cpuid; 1263 int forwarded = 0; 1264 int single_cpu = 0; 1265 1266 ts = td->td_sched; 1267 THREAD_LOCK_ASSERT(td, MA_OWNED); 1268 KASSERT((td->td_inhibitors == 0), 1269 ("sched_add: trying to run inhibited thread")); 1270 KASSERT((TD_CAN_RUN(td) || TD_IS_RUNNING(td)), 1271 ("sched_add: bad thread state")); 1272 KASSERT(td->td_flags & TDF_INMEM, 1273 ("sched_add: thread swapped out")); 1274 1275 KTR_STATE2(KTR_SCHED, "thread", sched_tdname(td), "runq add", 1276 "prio:%d", td->td_priority, KTR_ATTR_LINKED, 1277 sched_tdname(curthread)); 1278 KTR_POINT1(KTR_SCHED, "thread", sched_tdname(curthread), "wokeup", 1279 KTR_ATTR_LINKED, sched_tdname(td)); 1280 SDT_PROBE4(sched, , , enqueue, td, td->td_proc, NULL, 1281 flags & SRQ_PREEMPTED); 1282 1283 1284 /* 1285 * Now that the thread is moving to the run-queue, set the lock 1286 * to the scheduler's lock. 1287 */ 1288 if (td->td_lock != &sched_lock) { 1289 mtx_lock_spin(&sched_lock); 1290 thread_lock_set(td, &sched_lock); 1291 } 1292 TD_SET_RUNQ(td); 1293 1294 /* 1295 * If SMP is started and the thread is pinned or otherwise limited to 1296 * a specific set of CPUs, queue the thread to a per-CPU run queue. 1297 * Otherwise, queue the thread to the global run queue. 1298 * 1299 * If SMP has not yet been started we must use the global run queue 1300 * as per-CPU state may not be initialized yet and we may crash if we 1301 * try to access the per-CPU run queues. 1302 */ 1303 if (smp_started && (td->td_pinned != 0 || td->td_flags & TDF_BOUND || 1304 ts->ts_flags & TSF_AFFINITY)) { 1305 if (td->td_pinned != 0) 1306 cpu = td->td_lastcpu; 1307 else if (td->td_flags & TDF_BOUND) { 1308 /* Find CPU from bound runq. */ 1309 KASSERT(SKE_RUNQ_PCPU(ts), 1310 ("sched_add: bound td_sched not on cpu runq")); 1311 cpu = ts->ts_runq - &runq_pcpu[0]; 1312 } else 1313 /* Find a valid CPU for our cpuset */ 1314 cpu = sched_pickcpu(td); 1315 ts->ts_runq = &runq_pcpu[cpu]; 1316 single_cpu = 1; 1317 CTR3(KTR_RUNQ, 1318 "sched_add: Put td_sched:%p(td:%p) on cpu%d runq", ts, td, 1319 cpu); 1320 } else { 1321 CTR2(KTR_RUNQ, 1322 "sched_add: adding td_sched:%p (td:%p) to gbl runq", ts, 1323 td); 1324 cpu = NOCPU; 1325 ts->ts_runq = &runq; 1326 } 1327 1328 cpuid = PCPU_GET(cpuid); 1329 if (single_cpu && cpu != cpuid) { 1330 kick_other_cpu(td->td_priority, cpu); 1331 } else { 1332 if (!single_cpu) { 1333 tidlemsk = idle_cpus_mask; 1334 CPU_NAND(&tidlemsk, &hlt_cpus_mask); 1335 CPU_CLR(cpuid, &tidlemsk); 1336 1337 if (!CPU_ISSET(cpuid, &idle_cpus_mask) && 1338 ((flags & SRQ_INTR) == 0) && 1339 !CPU_EMPTY(&tidlemsk)) 1340 forwarded = forward_wakeup(cpu); 1341 } 1342 1343 if (!forwarded) { 1344 if ((flags & SRQ_YIELDING) == 0 && maybe_preempt(td)) 1345 return; 1346 else 1347 maybe_resched(td); 1348 } 1349 } 1350 1351 if ((td->td_flags & TDF_NOLOAD) == 0) 1352 sched_load_add(); 1353 runq_add(ts->ts_runq, td, flags); 1354 if (cpu != NOCPU) 1355 runq_length[cpu]++; 1356 } 1357 #else /* SMP */ 1358 { 1359 struct td_sched *ts; 1360 1361 ts = td->td_sched; 1362 THREAD_LOCK_ASSERT(td, MA_OWNED); 1363 KASSERT((td->td_inhibitors == 0), 1364 ("sched_add: trying to run inhibited thread")); 1365 KASSERT((TD_CAN_RUN(td) || TD_IS_RUNNING(td)), 1366 ("sched_add: bad thread state")); 1367 KASSERT(td->td_flags & TDF_INMEM, 1368 ("sched_add: thread swapped out")); 1369 KTR_STATE2(KTR_SCHED, "thread", sched_tdname(td), "runq add", 1370 "prio:%d", td->td_priority, KTR_ATTR_LINKED, 1371 sched_tdname(curthread)); 1372 KTR_POINT1(KTR_SCHED, "thread", sched_tdname(curthread), "wokeup", 1373 KTR_ATTR_LINKED, sched_tdname(td)); 1374 SDT_PROBE4(sched, , , enqueue, td, td->td_proc, NULL, 1375 flags & SRQ_PREEMPTED); 1376 1377 /* 1378 * Now that the thread is moving to the run-queue, set the lock 1379 * to the scheduler's lock. 1380 */ 1381 if (td->td_lock != &sched_lock) { 1382 mtx_lock_spin(&sched_lock); 1383 thread_lock_set(td, &sched_lock); 1384 } 1385 TD_SET_RUNQ(td); 1386 CTR2(KTR_RUNQ, "sched_add: adding td_sched:%p (td:%p) to runq", ts, td); 1387 ts->ts_runq = &runq; 1388 1389 /* 1390 * If we are yielding (on the way out anyhow) or the thread 1391 * being saved is US, then don't try be smart about preemption 1392 * or kicking off another CPU as it won't help and may hinder. 1393 * In the YIEDLING case, we are about to run whoever is being 1394 * put in the queue anyhow, and in the OURSELF case, we are 1395 * puting ourself on the run queue which also only happens 1396 * when we are about to yield. 1397 */ 1398 if ((flags & SRQ_YIELDING) == 0) { 1399 if (maybe_preempt(td)) 1400 return; 1401 } 1402 if ((td->td_flags & TDF_NOLOAD) == 0) 1403 sched_load_add(); 1404 runq_add(ts->ts_runq, td, flags); 1405 maybe_resched(td); 1406 } 1407 #endif /* SMP */ 1408 1409 void 1410 sched_rem(struct thread *td) 1411 { 1412 struct td_sched *ts; 1413 1414 ts = td->td_sched; 1415 KASSERT(td->td_flags & TDF_INMEM, 1416 ("sched_rem: thread swapped out")); 1417 KASSERT(TD_ON_RUNQ(td), 1418 ("sched_rem: thread not on run queue")); 1419 mtx_assert(&sched_lock, MA_OWNED); 1420 KTR_STATE2(KTR_SCHED, "thread", sched_tdname(td), "runq rem", 1421 "prio:%d", td->td_priority, KTR_ATTR_LINKED, 1422 sched_tdname(curthread)); 1423 SDT_PROBE3(sched, , , dequeue, td, td->td_proc, NULL); 1424 1425 if ((td->td_flags & TDF_NOLOAD) == 0) 1426 sched_load_rem(); 1427 #ifdef SMP 1428 if (ts->ts_runq != &runq) 1429 runq_length[ts->ts_runq - runq_pcpu]--; 1430 #endif 1431 runq_remove(ts->ts_runq, td); 1432 TD_SET_CAN_RUN(td); 1433 } 1434 1435 /* 1436 * Select threads to run. Note that running threads still consume a 1437 * slot. 1438 */ 1439 struct thread * 1440 sched_choose(void) 1441 { 1442 struct thread *td; 1443 struct runq *rq; 1444 1445 mtx_assert(&sched_lock, MA_OWNED); 1446 #ifdef SMP 1447 struct thread *tdcpu; 1448 1449 rq = &runq; 1450 td = runq_choose_fuzz(&runq, runq_fuzz); 1451 tdcpu = runq_choose(&runq_pcpu[PCPU_GET(cpuid)]); 1452 1453 if (td == NULL || 1454 (tdcpu != NULL && 1455 tdcpu->td_priority < td->td_priority)) { 1456 CTR2(KTR_RUNQ, "choosing td %p from pcpu runq %d", tdcpu, 1457 PCPU_GET(cpuid)); 1458 td = tdcpu; 1459 rq = &runq_pcpu[PCPU_GET(cpuid)]; 1460 } else { 1461 CTR1(KTR_RUNQ, "choosing td_sched %p from main runq", td); 1462 } 1463 1464 #else 1465 rq = &runq; 1466 td = runq_choose(&runq); 1467 #endif 1468 1469 if (td) { 1470 #ifdef SMP 1471 if (td == tdcpu) 1472 runq_length[PCPU_GET(cpuid)]--; 1473 #endif 1474 runq_remove(rq, td); 1475 td->td_flags |= TDF_DIDRUN; 1476 1477 KASSERT(td->td_flags & TDF_INMEM, 1478 ("sched_choose: thread swapped out")); 1479 return (td); 1480 } 1481 return (PCPU_GET(idlethread)); 1482 } 1483 1484 void 1485 sched_preempt(struct thread *td) 1486 { 1487 1488 SDT_PROBE2(sched, , , surrender, td, td->td_proc); 1489 thread_lock(td); 1490 if (td->td_critnest > 1) 1491 td->td_owepreempt = 1; 1492 else 1493 mi_switch(SW_INVOL | SW_PREEMPT | SWT_PREEMPT, NULL); 1494 thread_unlock(td); 1495 } 1496 1497 void 1498 sched_userret(struct thread *td) 1499 { 1500 /* 1501 * XXX we cheat slightly on the locking here to avoid locking in 1502 * the usual case. Setting td_priority here is essentially an 1503 * incomplete workaround for not setting it properly elsewhere. 1504 * Now that some interrupt handlers are threads, not setting it 1505 * properly elsewhere can clobber it in the window between setting 1506 * it here and returning to user mode, so don't waste time setting 1507 * it perfectly here. 1508 */ 1509 KASSERT((td->td_flags & TDF_BORROWING) == 0, 1510 ("thread with borrowed priority returning to userland")); 1511 if (td->td_priority != td->td_user_pri) { 1512 thread_lock(td); 1513 td->td_priority = td->td_user_pri; 1514 td->td_base_pri = td->td_user_pri; 1515 thread_unlock(td); 1516 } 1517 } 1518 1519 void 1520 sched_bind(struct thread *td, int cpu) 1521 { 1522 struct td_sched *ts; 1523 1524 THREAD_LOCK_ASSERT(td, MA_OWNED|MA_NOTRECURSED); 1525 KASSERT(td == curthread, ("sched_bind: can only bind curthread")); 1526 1527 ts = td->td_sched; 1528 1529 td->td_flags |= TDF_BOUND; 1530 #ifdef SMP 1531 ts->ts_runq = &runq_pcpu[cpu]; 1532 if (PCPU_GET(cpuid) == cpu) 1533 return; 1534 1535 mi_switch(SW_VOL, NULL); 1536 #endif 1537 } 1538 1539 void 1540 sched_unbind(struct thread* td) 1541 { 1542 THREAD_LOCK_ASSERT(td, MA_OWNED); 1543 KASSERT(td == curthread, ("sched_unbind: can only bind curthread")); 1544 td->td_flags &= ~TDF_BOUND; 1545 } 1546 1547 int 1548 sched_is_bound(struct thread *td) 1549 { 1550 THREAD_LOCK_ASSERT(td, MA_OWNED); 1551 return (td->td_flags & TDF_BOUND); 1552 } 1553 1554 void 1555 sched_relinquish(struct thread *td) 1556 { 1557 thread_lock(td); 1558 mi_switch(SW_VOL | SWT_RELINQUISH, NULL); 1559 thread_unlock(td); 1560 } 1561 1562 int 1563 sched_load(void) 1564 { 1565 return (sched_tdcnt); 1566 } 1567 1568 int 1569 sched_sizeof_proc(void) 1570 { 1571 return (sizeof(struct proc)); 1572 } 1573 1574 int 1575 sched_sizeof_thread(void) 1576 { 1577 return (sizeof(struct thread) + sizeof(struct td_sched)); 1578 } 1579 1580 fixpt_t 1581 sched_pctcpu(struct thread *td) 1582 { 1583 struct td_sched *ts; 1584 1585 THREAD_LOCK_ASSERT(td, MA_OWNED); 1586 ts = td->td_sched; 1587 return (ts->ts_pctcpu); 1588 } 1589 1590 #ifdef RACCT 1591 /* 1592 * Calculates the contribution to the thread cpu usage for the latest 1593 * (unfinished) second. 1594 */ 1595 fixpt_t 1596 sched_pctcpu_delta(struct thread *td) 1597 { 1598 struct td_sched *ts; 1599 fixpt_t delta; 1600 int realstathz; 1601 1602 THREAD_LOCK_ASSERT(td, MA_OWNED); 1603 ts = td->td_sched; 1604 delta = 0; 1605 realstathz = stathz ? stathz : hz; 1606 if (ts->ts_cpticks != 0) { 1607 #if (FSHIFT >= CCPU_SHIFT) 1608 delta = (realstathz == 100) 1609 ? ((fixpt_t) ts->ts_cpticks) << 1610 (FSHIFT - CCPU_SHIFT) : 1611 100 * (((fixpt_t) ts->ts_cpticks) 1612 << (FSHIFT - CCPU_SHIFT)) / realstathz; 1613 #else 1614 delta = ((FSCALE - ccpu) * 1615 (ts->ts_cpticks * 1616 FSCALE / realstathz)) >> FSHIFT; 1617 #endif 1618 } 1619 1620 return (delta); 1621 } 1622 #endif 1623 1624 void 1625 sched_tick(int cnt) 1626 { 1627 } 1628 1629 /* 1630 * The actual idle process. 1631 */ 1632 void 1633 sched_idletd(void *dummy) 1634 { 1635 struct pcpuidlestat *stat; 1636 1637 THREAD_NO_SLEEPING(); 1638 stat = DPCPU_PTR(idlestat); 1639 for (;;) { 1640 mtx_assert(&Giant, MA_NOTOWNED); 1641 1642 while (sched_runnable() == 0) { 1643 cpu_idle(stat->idlecalls + stat->oldidlecalls > 64); 1644 stat->idlecalls++; 1645 } 1646 1647 mtx_lock_spin(&sched_lock); 1648 mi_switch(SW_VOL | SWT_IDLE, NULL); 1649 mtx_unlock_spin(&sched_lock); 1650 } 1651 } 1652 1653 /* 1654 * A CPU is entering for the first time or a thread is exiting. 1655 */ 1656 void 1657 sched_throw(struct thread *td) 1658 { 1659 /* 1660 * Correct spinlock nesting. The idle thread context that we are 1661 * borrowing was created so that it would start out with a single 1662 * spin lock (sched_lock) held in fork_trampoline(). Since we've 1663 * explicitly acquired locks in this function, the nesting count 1664 * is now 2 rather than 1. Since we are nested, calling 1665 * spinlock_exit() will simply adjust the counts without allowing 1666 * spin lock using code to interrupt us. 1667 */ 1668 if (td == NULL) { 1669 mtx_lock_spin(&sched_lock); 1670 spinlock_exit(); 1671 PCPU_SET(switchtime, cpu_ticks()); 1672 PCPU_SET(switchticks, ticks); 1673 } else { 1674 lock_profile_release_lock(&sched_lock.lock_object); 1675 MPASS(td->td_lock == &sched_lock); 1676 td->td_lastcpu = td->td_oncpu; 1677 td->td_oncpu = NOCPU; 1678 } 1679 mtx_assert(&sched_lock, MA_OWNED); 1680 KASSERT(curthread->td_md.md_spinlock_count == 1, ("invalid count")); 1681 cpu_throw(td, choosethread()); /* doesn't return */ 1682 } 1683 1684 void 1685 sched_fork_exit(struct thread *td) 1686 { 1687 1688 /* 1689 * Finish setting up thread glue so that it begins execution in a 1690 * non-nested critical section with sched_lock held but not recursed. 1691 */ 1692 td->td_oncpu = PCPU_GET(cpuid); 1693 sched_lock.mtx_lock = (uintptr_t)td; 1694 lock_profile_obtain_lock_success(&sched_lock.lock_object, 1695 0, 0, __FILE__, __LINE__); 1696 THREAD_LOCK_ASSERT(td, MA_OWNED | MA_NOTRECURSED); 1697 } 1698 1699 char * 1700 sched_tdname(struct thread *td) 1701 { 1702 #ifdef KTR 1703 struct td_sched *ts; 1704 1705 ts = td->td_sched; 1706 if (ts->ts_name[0] == '\0') 1707 snprintf(ts->ts_name, sizeof(ts->ts_name), 1708 "%s tid %d", td->td_name, td->td_tid); 1709 return (ts->ts_name); 1710 #else 1711 return (td->td_name); 1712 #endif 1713 } 1714 1715 #ifdef KTR 1716 void 1717 sched_clear_tdname(struct thread *td) 1718 { 1719 struct td_sched *ts; 1720 1721 ts = td->td_sched; 1722 ts->ts_name[0] = '\0'; 1723 } 1724 #endif 1725 1726 void 1727 sched_affinity(struct thread *td) 1728 { 1729 #ifdef SMP 1730 struct td_sched *ts; 1731 int cpu; 1732 1733 THREAD_LOCK_ASSERT(td, MA_OWNED); 1734 1735 /* 1736 * Set the TSF_AFFINITY flag if there is at least one CPU this 1737 * thread can't run on. 1738 */ 1739 ts = td->td_sched; 1740 ts->ts_flags &= ~TSF_AFFINITY; 1741 CPU_FOREACH(cpu) { 1742 if (!THREAD_CAN_SCHED(td, cpu)) { 1743 ts->ts_flags |= TSF_AFFINITY; 1744 break; 1745 } 1746 } 1747 1748 /* 1749 * If this thread can run on all CPUs, nothing else to do. 1750 */ 1751 if (!(ts->ts_flags & TSF_AFFINITY)) 1752 return; 1753 1754 /* Pinned threads and bound threads should be left alone. */ 1755 if (td->td_pinned != 0 || td->td_flags & TDF_BOUND) 1756 return; 1757 1758 switch (td->td_state) { 1759 case TDS_RUNQ: 1760 /* 1761 * If we are on a per-CPU runqueue that is in the set, 1762 * then nothing needs to be done. 1763 */ 1764 if (ts->ts_runq != &runq && 1765 THREAD_CAN_SCHED(td, ts->ts_runq - runq_pcpu)) 1766 return; 1767 1768 /* Put this thread on a valid per-CPU runqueue. */ 1769 sched_rem(td); 1770 sched_add(td, SRQ_BORING); 1771 break; 1772 case TDS_RUNNING: 1773 /* 1774 * See if our current CPU is in the set. If not, force a 1775 * context switch. 1776 */ 1777 if (THREAD_CAN_SCHED(td, td->td_oncpu)) 1778 return; 1779 1780 td->td_flags |= TDF_NEEDRESCHED; 1781 if (td != curthread) 1782 ipi_cpu(cpu, IPI_AST); 1783 break; 1784 default: 1785 break; 1786 } 1787 #endif 1788 } 1789