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 * All fields are protected by the scheduler lock. 92 */ 93 struct td_sched { 94 fixpt_t ts_pctcpu; /* %cpu during p_swtime. */ 95 u_int ts_estcpu; /* Estimated cpu utilization. */ 96 int ts_cpticks; /* Ticks of cpu time. */ 97 int ts_slptime; /* Seconds !RUNNING. */ 98 int ts_slice; /* Remaining part of time slice. */ 99 int ts_flags; 100 struct runq *ts_runq; /* runq the thread is currently on */ 101 #ifdef KTR 102 char ts_name[TS_NAME_LEN]; 103 #endif 104 }; 105 106 /* flags kept in td_flags */ 107 #define TDF_DIDRUN TDF_SCHED0 /* thread actually ran. */ 108 #define TDF_BOUND TDF_SCHED1 /* Bound to one CPU. */ 109 #define TDF_SLICEEND TDF_SCHED2 /* Thread time slice is over. */ 110 111 /* flags kept in ts_flags */ 112 #define TSF_AFFINITY 0x0001 /* Has a non-"full" CPU set. */ 113 114 #define SKE_RUNQ_PCPU(ts) \ 115 ((ts)->ts_runq != 0 && (ts)->ts_runq != &runq) 116 117 #define THREAD_CAN_SCHED(td, cpu) \ 118 CPU_ISSET((cpu), &(td)->td_cpuset->cs_mask) 119 120 static struct td_sched td_sched0; 121 static struct mtx sched_lock; 122 123 static int realstathz = 127; /* stathz is sometimes 0 and run off of hz. */ 124 static int sched_tdcnt; /* Total runnable threads in the system. */ 125 static int sched_slice = 12; /* Thread run time before rescheduling. */ 126 127 static void setup_runqs(void); 128 static void schedcpu(void); 129 static void schedcpu_thread(void); 130 static void sched_priority(struct thread *td, u_char prio); 131 static void sched_setup(void *dummy); 132 static void maybe_resched(struct thread *td); 133 static void updatepri(struct thread *td); 134 static void resetpriority(struct thread *td); 135 static void resetpriority_thread(struct thread *td); 136 #ifdef SMP 137 static int sched_pickcpu(struct thread *td); 138 static int forward_wakeup(int cpunum); 139 static void kick_other_cpu(int pri, int cpuid); 140 #endif 141 142 static struct kproc_desc sched_kp = { 143 "schedcpu", 144 schedcpu_thread, 145 NULL 146 }; 147 SYSINIT(schedcpu, SI_SUB_LAST, SI_ORDER_FIRST, kproc_start, 148 &sched_kp); 149 SYSINIT(sched_setup, SI_SUB_RUN_QUEUE, SI_ORDER_FIRST, sched_setup, NULL); 150 151 static void sched_initticks(void *dummy); 152 SYSINIT(sched_initticks, SI_SUB_CLOCKS, SI_ORDER_THIRD, sched_initticks, 153 NULL); 154 155 /* 156 * Global run queue. 157 */ 158 static struct runq runq; 159 160 #ifdef SMP 161 /* 162 * Per-CPU run queues 163 */ 164 static struct runq runq_pcpu[MAXCPU]; 165 long runq_length[MAXCPU]; 166 167 static cpuset_t idle_cpus_mask; 168 #endif 169 170 struct pcpuidlestat { 171 u_int idlecalls; 172 u_int oldidlecalls; 173 }; 174 static DPCPU_DEFINE(struct pcpuidlestat, idlestat); 175 176 static void 177 setup_runqs(void) 178 { 179 #ifdef SMP 180 int i; 181 182 for (i = 0; i < MAXCPU; ++i) 183 runq_init(&runq_pcpu[i]); 184 #endif 185 186 runq_init(&runq); 187 } 188 189 static int 190 sysctl_kern_quantum(SYSCTL_HANDLER_ARGS) 191 { 192 int error, new_val, period; 193 194 period = 1000000 / realstathz; 195 new_val = period * sched_slice; 196 error = sysctl_handle_int(oidp, &new_val, 0, req); 197 if (error != 0 || req->newptr == NULL) 198 return (error); 199 if (new_val <= 0) 200 return (EINVAL); 201 sched_slice = imax(1, (new_val + period / 2) / period); 202 hogticks = imax(1, (2 * hz * sched_slice + realstathz / 2) / 203 realstathz); 204 return (0); 205 } 206 207 SYSCTL_NODE(_kern, OID_AUTO, sched, CTLFLAG_RD, 0, "Scheduler"); 208 209 SYSCTL_STRING(_kern_sched, OID_AUTO, name, CTLFLAG_RD, "4BSD", 0, 210 "Scheduler name"); 211 SYSCTL_PROC(_kern_sched, OID_AUTO, quantum, CTLTYPE_INT | CTLFLAG_RW, 212 NULL, 0, sysctl_kern_quantum, "I", 213 "Quantum for timeshare threads in microseconds"); 214 SYSCTL_INT(_kern_sched, OID_AUTO, slice, CTLFLAG_RW, &sched_slice, 0, 215 "Quantum for timeshare threads in stathz ticks"); 216 #ifdef SMP 217 /* Enable forwarding of wakeups to all other cpus */ 218 static SYSCTL_NODE(_kern_sched, OID_AUTO, ipiwakeup, CTLFLAG_RD, NULL, 219 "Kernel SMP"); 220 221 static int runq_fuzz = 1; 222 SYSCTL_INT(_kern_sched, OID_AUTO, runq_fuzz, CTLFLAG_RW, &runq_fuzz, 0, ""); 223 224 static int forward_wakeup_enabled = 1; 225 SYSCTL_INT(_kern_sched_ipiwakeup, OID_AUTO, enabled, CTLFLAG_RW, 226 &forward_wakeup_enabled, 0, 227 "Forwarding of wakeup to idle CPUs"); 228 229 static int forward_wakeups_requested = 0; 230 SYSCTL_INT(_kern_sched_ipiwakeup, OID_AUTO, requested, CTLFLAG_RD, 231 &forward_wakeups_requested, 0, 232 "Requests for Forwarding of wakeup to idle CPUs"); 233 234 static int forward_wakeups_delivered = 0; 235 SYSCTL_INT(_kern_sched_ipiwakeup, OID_AUTO, delivered, CTLFLAG_RD, 236 &forward_wakeups_delivered, 0, 237 "Completed Forwarding of wakeup to idle CPUs"); 238 239 static int forward_wakeup_use_mask = 1; 240 SYSCTL_INT(_kern_sched_ipiwakeup, OID_AUTO, usemask, CTLFLAG_RW, 241 &forward_wakeup_use_mask, 0, 242 "Use the mask of idle cpus"); 243 244 static int forward_wakeup_use_loop = 0; 245 SYSCTL_INT(_kern_sched_ipiwakeup, OID_AUTO, useloop, CTLFLAG_RW, 246 &forward_wakeup_use_loop, 0, 247 "Use a loop to find idle cpus"); 248 249 #endif 250 #if 0 251 static int sched_followon = 0; 252 SYSCTL_INT(_kern_sched, OID_AUTO, followon, CTLFLAG_RW, 253 &sched_followon, 0, 254 "allow threads to share a quantum"); 255 #endif 256 257 SDT_PROVIDER_DEFINE(sched); 258 259 SDT_PROBE_DEFINE3(sched, , , change__pri, "struct thread *", 260 "struct proc *", "uint8_t"); 261 SDT_PROBE_DEFINE3(sched, , , dequeue, "struct thread *", 262 "struct proc *", "void *"); 263 SDT_PROBE_DEFINE4(sched, , , enqueue, "struct thread *", 264 "struct proc *", "void *", "int"); 265 SDT_PROBE_DEFINE4(sched, , , lend__pri, "struct thread *", 266 "struct proc *", "uint8_t", "struct thread *"); 267 SDT_PROBE_DEFINE2(sched, , , load__change, "int", "int"); 268 SDT_PROBE_DEFINE2(sched, , , off__cpu, "struct thread *", 269 "struct proc *"); 270 SDT_PROBE_DEFINE(sched, , , on__cpu); 271 SDT_PROBE_DEFINE(sched, , , remain__cpu); 272 SDT_PROBE_DEFINE2(sched, , , surrender, "struct thread *", 273 "struct proc *"); 274 275 static __inline void 276 sched_load_add(void) 277 { 278 279 sched_tdcnt++; 280 KTR_COUNTER0(KTR_SCHED, "load", "global load", sched_tdcnt); 281 SDT_PROBE2(sched, , , load__change, NOCPU, sched_tdcnt); 282 } 283 284 static __inline void 285 sched_load_rem(void) 286 { 287 288 sched_tdcnt--; 289 KTR_COUNTER0(KTR_SCHED, "load", "global load", sched_tdcnt); 290 SDT_PROBE2(sched, , , load__change, NOCPU, sched_tdcnt); 291 } 292 /* 293 * Arrange to reschedule if necessary, taking the priorities and 294 * schedulers into account. 295 */ 296 static void 297 maybe_resched(struct thread *td) 298 { 299 300 THREAD_LOCK_ASSERT(td, MA_OWNED); 301 if (td->td_priority < curthread->td_priority) 302 curthread->td_flags |= TDF_NEEDRESCHED; 303 } 304 305 /* 306 * This function is called when a thread is about to be put on run queue 307 * because it has been made runnable or its priority has been adjusted. It 308 * determines if the new thread should be immediately preempted to. If so, 309 * it switches to it and eventually returns true. If not, it returns false 310 * so that the caller may place the thread on an appropriate run queue. 311 */ 312 int 313 maybe_preempt(struct thread *td) 314 { 315 #ifdef PREEMPTION 316 struct thread *ctd; 317 int cpri, pri; 318 319 /* 320 * The new thread should not preempt the current thread if any of the 321 * following conditions are true: 322 * 323 * - The kernel is in the throes of crashing (panicstr). 324 * - The current thread has a higher (numerically lower) or 325 * equivalent priority. Note that this prevents curthread from 326 * trying to preempt to itself. 327 * - It is too early in the boot for context switches (cold is set). 328 * - The current thread has an inhibitor set or is in the process of 329 * exiting. In this case, the current thread is about to switch 330 * out anyways, so there's no point in preempting. If we did, 331 * the current thread would not be properly resumed as well, so 332 * just avoid that whole landmine. 333 * - If the new thread's priority is not a realtime priority and 334 * the current thread's priority is not an idle priority and 335 * FULL_PREEMPTION is disabled. 336 * 337 * If all of these conditions are false, but the current thread is in 338 * a nested critical section, then we have to defer the preemption 339 * until we exit the critical section. Otherwise, switch immediately 340 * to the new thread. 341 */ 342 ctd = curthread; 343 THREAD_LOCK_ASSERT(td, MA_OWNED); 344 KASSERT((td->td_inhibitors == 0), 345 ("maybe_preempt: trying to run inhibited thread")); 346 pri = td->td_priority; 347 cpri = ctd->td_priority; 348 if (panicstr != NULL || pri >= cpri || cold /* || dumping */ || 349 TD_IS_INHIBITED(ctd)) 350 return (0); 351 #ifndef FULL_PREEMPTION 352 if (pri > PRI_MAX_ITHD && cpri < PRI_MIN_IDLE) 353 return (0); 354 #endif 355 356 if (ctd->td_critnest > 1) { 357 CTR1(KTR_PROC, "maybe_preempt: in critical section %d", 358 ctd->td_critnest); 359 ctd->td_owepreempt = 1; 360 return (0); 361 } 362 /* 363 * Thread is runnable but not yet put on system run queue. 364 */ 365 MPASS(ctd->td_lock == td->td_lock); 366 MPASS(TD_ON_RUNQ(td)); 367 TD_SET_RUNNING(td); 368 CTR3(KTR_PROC, "preempting to thread %p (pid %d, %s)\n", td, 369 td->td_proc->p_pid, td->td_name); 370 mi_switch(SW_INVOL | SW_PREEMPT | SWT_PREEMPT, td); 371 /* 372 * td's lock pointer may have changed. We have to return with it 373 * locked. 374 */ 375 spinlock_enter(); 376 thread_unlock(ctd); 377 thread_lock(td); 378 spinlock_exit(); 379 return (1); 380 #else 381 return (0); 382 #endif 383 } 384 385 /* 386 * Constants for digital decay and forget: 387 * 90% of (ts_estcpu) usage in 5 * loadav time 388 * 95% of (ts_pctcpu) usage in 60 seconds (load insensitive) 389 * Note that, as ps(1) mentions, this can let percentages 390 * total over 100% (I've seen 137.9% for 3 processes). 391 * 392 * Note that schedclock() updates ts_estcpu and p_cpticks asynchronously. 393 * 394 * We wish to decay away 90% of ts_estcpu in (5 * loadavg) seconds. 395 * That is, the system wants to compute a value of decay such 396 * that the following for loop: 397 * for (i = 0; i < (5 * loadavg); i++) 398 * ts_estcpu *= decay; 399 * will compute 400 * ts_estcpu *= 0.1; 401 * for all values of loadavg: 402 * 403 * Mathematically this loop can be expressed by saying: 404 * decay ** (5 * loadavg) ~= .1 405 * 406 * The system computes decay as: 407 * decay = (2 * loadavg) / (2 * loadavg + 1) 408 * 409 * We wish to prove that the system's computation of decay 410 * will always fulfill the equation: 411 * decay ** (5 * loadavg) ~= .1 412 * 413 * If we compute b as: 414 * b = 2 * loadavg 415 * then 416 * decay = b / (b + 1) 417 * 418 * We now need to prove two things: 419 * 1) Given factor ** (5 * loadavg) ~= .1, prove factor == b/(b+1) 420 * 2) Given b/(b+1) ** power ~= .1, prove power == (5 * loadavg) 421 * 422 * Facts: 423 * For x close to zero, exp(x) =~ 1 + x, since 424 * exp(x) = 0! + x**1/1! + x**2/2! + ... . 425 * therefore exp(-1/b) =~ 1 - (1/b) = (b-1)/b. 426 * For x close to zero, ln(1+x) =~ x, since 427 * ln(1+x) = x - x**2/2 + x**3/3 - ... -1 < x < 1 428 * therefore ln(b/(b+1)) = ln(1 - 1/(b+1)) =~ -1/(b+1). 429 * ln(.1) =~ -2.30 430 * 431 * Proof of (1): 432 * Solve (factor)**(power) =~ .1 given power (5*loadav): 433 * solving for factor, 434 * ln(factor) =~ (-2.30/5*loadav), or 435 * factor =~ exp(-1/((5/2.30)*loadav)) =~ exp(-1/(2*loadav)) = 436 * exp(-1/b) =~ (b-1)/b =~ b/(b+1). QED 437 * 438 * Proof of (2): 439 * Solve (factor)**(power) =~ .1 given factor == (b/(b+1)): 440 * solving for power, 441 * power*ln(b/(b+1)) =~ -2.30, or 442 * power =~ 2.3 * (b + 1) = 4.6*loadav + 2.3 =~ 5*loadav. QED 443 * 444 * Actual power values for the implemented algorithm are as follows: 445 * loadav: 1 2 3 4 446 * power: 5.68 10.32 14.94 19.55 447 */ 448 449 /* calculations for digital decay to forget 90% of usage in 5*loadav sec */ 450 #define loadfactor(loadav) (2 * (loadav)) 451 #define decay_cpu(loadfac, cpu) (((loadfac) * (cpu)) / ((loadfac) + FSCALE)) 452 453 /* decay 95% of `ts_pctcpu' in 60 seconds; see CCPU_SHIFT before changing */ 454 static fixpt_t ccpu = 0.95122942450071400909 * FSCALE; /* exp(-1/20) */ 455 SYSCTL_UINT(_kern, OID_AUTO, ccpu, CTLFLAG_RD, &ccpu, 0, ""); 456 457 /* 458 * If `ccpu' is not equal to `exp(-1/20)' and you still want to use the 459 * faster/more-accurate formula, you'll have to estimate CCPU_SHIFT below 460 * and possibly adjust FSHIFT in "param.h" so that (FSHIFT >= CCPU_SHIFT). 461 * 462 * To estimate CCPU_SHIFT for exp(-1/20), the following formula was used: 463 * 1 - exp(-1/20) ~= 0.0487 ~= 0.0488 == 1 (fixed pt, *11* bits). 464 * 465 * If you don't want to bother with the faster/more-accurate formula, you 466 * can set CCPU_SHIFT to (FSHIFT + 1) which will use a slower/less-accurate 467 * (more general) method of calculating the %age of CPU used by a process. 468 */ 469 #define CCPU_SHIFT 11 470 471 /* 472 * Recompute process priorities, every hz ticks. 473 * MP-safe, called without the Giant mutex. 474 */ 475 /* ARGSUSED */ 476 static void 477 schedcpu(void) 478 { 479 register fixpt_t loadfac = loadfactor(averunnable.ldavg[0]); 480 struct thread *td; 481 struct proc *p; 482 struct td_sched *ts; 483 int awake; 484 485 sx_slock(&allproc_lock); 486 FOREACH_PROC_IN_SYSTEM(p) { 487 PROC_LOCK(p); 488 if (p->p_state == PRS_NEW) { 489 PROC_UNLOCK(p); 490 continue; 491 } 492 FOREACH_THREAD_IN_PROC(p, td) { 493 awake = 0; 494 thread_lock(td); 495 ts = td->td_sched; 496 /* 497 * Increment sleep time (if sleeping). We 498 * ignore overflow, as above. 499 */ 500 /* 501 * The td_sched slptimes are not touched in wakeup 502 * because the thread may not HAVE everything in 503 * memory? XXX I think this is out of date. 504 */ 505 if (TD_ON_RUNQ(td)) { 506 awake = 1; 507 td->td_flags &= ~TDF_DIDRUN; 508 } else if (TD_IS_RUNNING(td)) { 509 awake = 1; 510 /* Do not clear TDF_DIDRUN */ 511 } else if (td->td_flags & TDF_DIDRUN) { 512 awake = 1; 513 td->td_flags &= ~TDF_DIDRUN; 514 } 515 516 /* 517 * ts_pctcpu is only for ps and ttyinfo(). 518 */ 519 ts->ts_pctcpu = (ts->ts_pctcpu * ccpu) >> FSHIFT; 520 /* 521 * If the td_sched has been idle the entire second, 522 * stop recalculating its priority until 523 * it wakes up. 524 */ 525 if (ts->ts_cpticks != 0) { 526 #if (FSHIFT >= CCPU_SHIFT) 527 ts->ts_pctcpu += (realstathz == 100) 528 ? ((fixpt_t) ts->ts_cpticks) << 529 (FSHIFT - CCPU_SHIFT) : 530 100 * (((fixpt_t) ts->ts_cpticks) 531 << (FSHIFT - CCPU_SHIFT)) / realstathz; 532 #else 533 ts->ts_pctcpu += ((FSCALE - ccpu) * 534 (ts->ts_cpticks * 535 FSCALE / realstathz)) >> FSHIFT; 536 #endif 537 ts->ts_cpticks = 0; 538 } 539 /* 540 * If there are ANY running threads in this process, 541 * then don't count it as sleeping. 542 * XXX: this is broken. 543 */ 544 if (awake) { 545 if (ts->ts_slptime > 1) { 546 /* 547 * In an ideal world, this should not 548 * happen, because whoever woke us 549 * up from the long sleep should have 550 * unwound the slptime and reset our 551 * priority before we run at the stale 552 * priority. Should KASSERT at some 553 * point when all the cases are fixed. 554 */ 555 updatepri(td); 556 } 557 ts->ts_slptime = 0; 558 } else 559 ts->ts_slptime++; 560 if (ts->ts_slptime > 1) { 561 thread_unlock(td); 562 continue; 563 } 564 ts->ts_estcpu = decay_cpu(loadfac, ts->ts_estcpu); 565 resetpriority(td); 566 resetpriority_thread(td); 567 thread_unlock(td); 568 } 569 PROC_UNLOCK(p); 570 } 571 sx_sunlock(&allproc_lock); 572 } 573 574 /* 575 * Main loop for a kthread that executes schedcpu once a second. 576 */ 577 static void 578 schedcpu_thread(void) 579 { 580 581 for (;;) { 582 schedcpu(); 583 pause("-", hz); 584 } 585 } 586 587 /* 588 * Recalculate the priority of a process after it has slept for a while. 589 * For all load averages >= 1 and max ts_estcpu of 255, sleeping for at 590 * least six times the loadfactor will decay ts_estcpu to zero. 591 */ 592 static void 593 updatepri(struct thread *td) 594 { 595 struct td_sched *ts; 596 fixpt_t loadfac; 597 unsigned int newcpu; 598 599 ts = td->td_sched; 600 loadfac = loadfactor(averunnable.ldavg[0]); 601 if (ts->ts_slptime > 5 * loadfac) 602 ts->ts_estcpu = 0; 603 else { 604 newcpu = ts->ts_estcpu; 605 ts->ts_slptime--; /* was incremented in schedcpu() */ 606 while (newcpu && --ts->ts_slptime) 607 newcpu = decay_cpu(loadfac, newcpu); 608 ts->ts_estcpu = newcpu; 609 } 610 } 611 612 /* 613 * Compute the priority of a process when running in user mode. 614 * Arrange to reschedule if the resulting priority is better 615 * than that of the current process. 616 */ 617 static void 618 resetpriority(struct thread *td) 619 { 620 u_int newpriority; 621 622 if (td->td_pri_class != PRI_TIMESHARE) 623 return; 624 newpriority = PUSER + td->td_sched->ts_estcpu / INVERSE_ESTCPU_WEIGHT + 625 NICE_WEIGHT * (td->td_proc->p_nice - PRIO_MIN); 626 newpriority = min(max(newpriority, PRI_MIN_TIMESHARE), 627 PRI_MAX_TIMESHARE); 628 sched_user_prio(td, newpriority); 629 } 630 631 /* 632 * Update the thread's priority when the associated process's user 633 * priority changes. 634 */ 635 static void 636 resetpriority_thread(struct thread *td) 637 { 638 639 /* Only change threads with a time sharing user priority. */ 640 if (td->td_priority < PRI_MIN_TIMESHARE || 641 td->td_priority > PRI_MAX_TIMESHARE) 642 return; 643 644 /* XXX the whole needresched thing is broken, but not silly. */ 645 maybe_resched(td); 646 647 sched_prio(td, td->td_user_pri); 648 } 649 650 /* ARGSUSED */ 651 static void 652 sched_setup(void *dummy) 653 { 654 655 setup_runqs(); 656 657 /* Account for thread0. */ 658 sched_load_add(); 659 } 660 661 /* 662 * This routine determines time constants after stathz and hz are setup. 663 */ 664 static void 665 sched_initticks(void *dummy) 666 { 667 668 realstathz = stathz ? stathz : hz; 669 sched_slice = realstathz / 10; /* ~100ms */ 670 hogticks = imax(1, (2 * hz * sched_slice + realstathz / 2) / 671 realstathz); 672 } 673 674 /* External interfaces start here */ 675 676 /* 677 * Very early in the boot some setup of scheduler-specific 678 * parts of proc0 and of some scheduler resources needs to be done. 679 * Called from: 680 * proc0_init() 681 */ 682 void 683 schedinit(void) 684 { 685 /* 686 * Set up the scheduler specific parts of proc0. 687 */ 688 proc0.p_sched = NULL; /* XXX */ 689 thread0.td_sched = &td_sched0; 690 thread0.td_lock = &sched_lock; 691 td_sched0.ts_slice = sched_slice; 692 mtx_init(&sched_lock, "sched lock", NULL, MTX_SPIN | MTX_RECURSE); 693 } 694 695 int 696 sched_runnable(void) 697 { 698 #ifdef SMP 699 return runq_check(&runq) + runq_check(&runq_pcpu[PCPU_GET(cpuid)]); 700 #else 701 return runq_check(&runq); 702 #endif 703 } 704 705 int 706 sched_rr_interval(void) 707 { 708 709 /* Convert sched_slice from stathz to hz. */ 710 return (imax(1, (sched_slice * hz + realstathz / 2) / realstathz)); 711 } 712 713 /* 714 * We adjust the priority of the current process. The priority of a 715 * process gets worse as it accumulates CPU time. The cpu usage 716 * estimator (ts_estcpu) is increased here. resetpriority() will 717 * compute a different priority each time ts_estcpu increases by 718 * INVERSE_ESTCPU_WEIGHT (until PRI_MAX_TIMESHARE is reached). The 719 * cpu usage estimator ramps up quite quickly when the process is 720 * running (linearly), and decays away exponentially, at a rate which 721 * is proportionally slower when the system is busy. The basic 722 * principle is that the system will 90% forget that the process used 723 * a lot of CPU time in 5 * loadav seconds. This causes the system to 724 * favor processes which haven't run much recently, and to round-robin 725 * among other processes. 726 */ 727 void 728 sched_clock(struct thread *td) 729 { 730 struct pcpuidlestat *stat; 731 struct td_sched *ts; 732 733 THREAD_LOCK_ASSERT(td, MA_OWNED); 734 ts = td->td_sched; 735 736 ts->ts_cpticks++; 737 ts->ts_estcpu = ESTCPULIM(ts->ts_estcpu + 1); 738 if ((ts->ts_estcpu % INVERSE_ESTCPU_WEIGHT) == 0) { 739 resetpriority(td); 740 resetpriority_thread(td); 741 } 742 743 /* 744 * Force a context switch if the current thread has used up a full 745 * time slice (default is 100ms). 746 */ 747 if (!TD_IS_IDLETHREAD(td) && --ts->ts_slice <= 0) { 748 ts->ts_slice = sched_slice; 749 td->td_flags |= TDF_NEEDRESCHED | TDF_SLICEEND; 750 } 751 752 stat = DPCPU_PTR(idlestat); 753 stat->oldidlecalls = stat->idlecalls; 754 stat->idlecalls = 0; 755 } 756 757 /* 758 * Charge child's scheduling CPU usage to parent. 759 */ 760 void 761 sched_exit(struct proc *p, struct thread *td) 762 { 763 764 KTR_STATE1(KTR_SCHED, "thread", sched_tdname(td), "proc exit", 765 "prio:%d", td->td_priority); 766 767 PROC_LOCK_ASSERT(p, MA_OWNED); 768 sched_exit_thread(FIRST_THREAD_IN_PROC(p), td); 769 } 770 771 void 772 sched_exit_thread(struct thread *td, struct thread *child) 773 { 774 775 KTR_STATE1(KTR_SCHED, "thread", sched_tdname(child), "exit", 776 "prio:%d", child->td_priority); 777 thread_lock(td); 778 td->td_sched->ts_estcpu = ESTCPULIM(td->td_sched->ts_estcpu + 779 child->td_sched->ts_estcpu); 780 thread_unlock(td); 781 thread_lock(child); 782 if ((child->td_flags & TDF_NOLOAD) == 0) 783 sched_load_rem(); 784 thread_unlock(child); 785 } 786 787 void 788 sched_fork(struct thread *td, struct thread *childtd) 789 { 790 sched_fork_thread(td, childtd); 791 } 792 793 void 794 sched_fork_thread(struct thread *td, struct thread *childtd) 795 { 796 struct td_sched *ts; 797 798 childtd->td_oncpu = NOCPU; 799 childtd->td_lastcpu = NOCPU; 800 childtd->td_lock = &sched_lock; 801 childtd->td_cpuset = cpuset_ref(td->td_cpuset); 802 childtd->td_priority = childtd->td_base_pri; 803 ts = childtd->td_sched; 804 bzero(ts, sizeof(*ts)); 805 ts->ts_estcpu = td->td_sched->ts_estcpu; 806 ts->ts_flags |= (td->td_sched->ts_flags & TSF_AFFINITY); 807 ts->ts_slice = 1; 808 } 809 810 void 811 sched_nice(struct proc *p, int nice) 812 { 813 struct thread *td; 814 815 PROC_LOCK_ASSERT(p, MA_OWNED); 816 p->p_nice = nice; 817 FOREACH_THREAD_IN_PROC(p, td) { 818 thread_lock(td); 819 resetpriority(td); 820 resetpriority_thread(td); 821 thread_unlock(td); 822 } 823 } 824 825 void 826 sched_class(struct thread *td, int class) 827 { 828 THREAD_LOCK_ASSERT(td, MA_OWNED); 829 td->td_pri_class = class; 830 } 831 832 /* 833 * Adjust the priority of a thread. 834 */ 835 static void 836 sched_priority(struct thread *td, u_char prio) 837 { 838 839 840 KTR_POINT3(KTR_SCHED, "thread", sched_tdname(td), "priority change", 841 "prio:%d", td->td_priority, "new prio:%d", prio, KTR_ATTR_LINKED, 842 sched_tdname(curthread)); 843 SDT_PROBE3(sched, , , change__pri, td, td->td_proc, prio); 844 if (td != curthread && prio > td->td_priority) { 845 KTR_POINT3(KTR_SCHED, "thread", sched_tdname(curthread), 846 "lend prio", "prio:%d", td->td_priority, "new prio:%d", 847 prio, KTR_ATTR_LINKED, sched_tdname(td)); 848 SDT_PROBE4(sched, , , lend__pri, td, td->td_proc, prio, 849 curthread); 850 } 851 THREAD_LOCK_ASSERT(td, MA_OWNED); 852 if (td->td_priority == prio) 853 return; 854 td->td_priority = prio; 855 if (TD_ON_RUNQ(td) && td->td_rqindex != (prio / RQ_PPQ)) { 856 sched_rem(td); 857 sched_add(td, SRQ_BORING); 858 } 859 } 860 861 /* 862 * Update a thread's priority when it is lent another thread's 863 * priority. 864 */ 865 void 866 sched_lend_prio(struct thread *td, u_char prio) 867 { 868 869 td->td_flags |= TDF_BORROWING; 870 sched_priority(td, prio); 871 } 872 873 /* 874 * Restore a thread's priority when priority propagation is 875 * over. The prio argument is the minimum priority the thread 876 * needs to have to satisfy other possible priority lending 877 * requests. If the thread's regulary priority is less 878 * important than prio the thread will keep a priority boost 879 * of prio. 880 */ 881 void 882 sched_unlend_prio(struct thread *td, u_char prio) 883 { 884 u_char base_pri; 885 886 if (td->td_base_pri >= PRI_MIN_TIMESHARE && 887 td->td_base_pri <= PRI_MAX_TIMESHARE) 888 base_pri = td->td_user_pri; 889 else 890 base_pri = td->td_base_pri; 891 if (prio >= base_pri) { 892 td->td_flags &= ~TDF_BORROWING; 893 sched_prio(td, base_pri); 894 } else 895 sched_lend_prio(td, prio); 896 } 897 898 void 899 sched_prio(struct thread *td, u_char prio) 900 { 901 u_char oldprio; 902 903 /* First, update the base priority. */ 904 td->td_base_pri = prio; 905 906 /* 907 * If the thread is borrowing another thread's priority, don't ever 908 * lower the priority. 909 */ 910 if (td->td_flags & TDF_BORROWING && td->td_priority < prio) 911 return; 912 913 /* Change the real priority. */ 914 oldprio = td->td_priority; 915 sched_priority(td, prio); 916 917 /* 918 * If the thread is on a turnstile, then let the turnstile update 919 * its state. 920 */ 921 if (TD_ON_LOCK(td) && oldprio != prio) 922 turnstile_adjust(td, oldprio); 923 } 924 925 void 926 sched_user_prio(struct thread *td, u_char prio) 927 { 928 929 THREAD_LOCK_ASSERT(td, MA_OWNED); 930 td->td_base_user_pri = prio; 931 if (td->td_lend_user_pri <= prio) 932 return; 933 td->td_user_pri = prio; 934 } 935 936 void 937 sched_lend_user_prio(struct thread *td, u_char prio) 938 { 939 940 THREAD_LOCK_ASSERT(td, MA_OWNED); 941 td->td_lend_user_pri = prio; 942 td->td_user_pri = min(prio, td->td_base_user_pri); 943 if (td->td_priority > td->td_user_pri) 944 sched_prio(td, td->td_user_pri); 945 else if (td->td_priority != td->td_user_pri) 946 td->td_flags |= TDF_NEEDRESCHED; 947 } 948 949 void 950 sched_sleep(struct thread *td, int pri) 951 { 952 953 THREAD_LOCK_ASSERT(td, MA_OWNED); 954 td->td_slptick = ticks; 955 td->td_sched->ts_slptime = 0; 956 if (pri != 0 && PRI_BASE(td->td_pri_class) == PRI_TIMESHARE) 957 sched_prio(td, pri); 958 if (TD_IS_SUSPENDED(td) || pri >= PSOCK) 959 td->td_flags |= TDF_CANSWAP; 960 } 961 962 void 963 sched_switch(struct thread *td, struct thread *newtd, int flags) 964 { 965 struct mtx *tmtx; 966 struct td_sched *ts; 967 struct proc *p; 968 int preempted; 969 970 tmtx = NULL; 971 ts = td->td_sched; 972 p = td->td_proc; 973 974 THREAD_LOCK_ASSERT(td, MA_OWNED); 975 976 /* 977 * Switch to the sched lock to fix things up and pick 978 * a new thread. 979 * Block the td_lock in order to avoid breaking the critical path. 980 */ 981 if (td->td_lock != &sched_lock) { 982 mtx_lock_spin(&sched_lock); 983 tmtx = thread_lock_block(td); 984 } 985 986 if ((td->td_flags & TDF_NOLOAD) == 0) 987 sched_load_rem(); 988 989 td->td_lastcpu = td->td_oncpu; 990 preempted = !((td->td_flags & TDF_SLICEEND) || 991 (flags & SWT_RELINQUISH)); 992 td->td_flags &= ~(TDF_NEEDRESCHED | TDF_SLICEEND); 993 td->td_owepreempt = 0; 994 td->td_oncpu = NOCPU; 995 996 /* 997 * At the last moment, if this thread is still marked RUNNING, 998 * then put it back on the run queue as it has not been suspended 999 * or stopped or any thing else similar. We never put the idle 1000 * threads on the run queue, however. 1001 */ 1002 if (td->td_flags & TDF_IDLETD) { 1003 TD_SET_CAN_RUN(td); 1004 #ifdef SMP 1005 CPU_CLR(PCPU_GET(cpuid), &idle_cpus_mask); 1006 #endif 1007 } else { 1008 if (TD_IS_RUNNING(td)) { 1009 /* Put us back on the run queue. */ 1010 sched_add(td, preempted ? 1011 SRQ_OURSELF|SRQ_YIELDING|SRQ_PREEMPTED : 1012 SRQ_OURSELF|SRQ_YIELDING); 1013 } 1014 } 1015 if (newtd) { 1016 /* 1017 * The thread we are about to run needs to be counted 1018 * as if it had been added to the run queue and selected. 1019 * It came from: 1020 * * A preemption 1021 * * An upcall 1022 * * A followon 1023 */ 1024 KASSERT((newtd->td_inhibitors == 0), 1025 ("trying to run inhibited thread")); 1026 newtd->td_flags |= TDF_DIDRUN; 1027 TD_SET_RUNNING(newtd); 1028 if ((newtd->td_flags & TDF_NOLOAD) == 0) 1029 sched_load_add(); 1030 } else { 1031 newtd = choosethread(); 1032 MPASS(newtd->td_lock == &sched_lock); 1033 } 1034 1035 if (td != newtd) { 1036 #ifdef HWPMC_HOOKS 1037 if (PMC_PROC_IS_USING_PMCS(td->td_proc)) 1038 PMC_SWITCH_CONTEXT(td, PMC_FN_CSW_OUT); 1039 #endif 1040 1041 SDT_PROBE2(sched, , , off__cpu, newtd, newtd->td_proc); 1042 1043 /* I feel sleepy */ 1044 lock_profile_release_lock(&sched_lock.lock_object); 1045 #ifdef KDTRACE_HOOKS 1046 /* 1047 * If DTrace has set the active vtime enum to anything 1048 * other than INACTIVE (0), then it should have set the 1049 * function to call. 1050 */ 1051 if (dtrace_vtime_active) 1052 (*dtrace_vtime_switch_func)(newtd); 1053 #endif 1054 1055 cpu_switch(td, newtd, tmtx != NULL ? tmtx : td->td_lock); 1056 lock_profile_obtain_lock_success(&sched_lock.lock_object, 1057 0, 0, __FILE__, __LINE__); 1058 /* 1059 * Where am I? What year is it? 1060 * We are in the same thread that went to sleep above, 1061 * but any amount of time may have passed. All our context 1062 * will still be available as will local variables. 1063 * PCPU values however may have changed as we may have 1064 * changed CPU so don't trust cached values of them. 1065 * New threads will go to fork_exit() instead of here 1066 * so if you change things here you may need to change 1067 * things there too. 1068 * 1069 * If the thread above was exiting it will never wake 1070 * up again here, so either it has saved everything it 1071 * needed to, or the thread_wait() or wait() will 1072 * need to reap it. 1073 */ 1074 1075 SDT_PROBE0(sched, , , on__cpu); 1076 #ifdef HWPMC_HOOKS 1077 if (PMC_PROC_IS_USING_PMCS(td->td_proc)) 1078 PMC_SWITCH_CONTEXT(td, PMC_FN_CSW_IN); 1079 #endif 1080 } else 1081 SDT_PROBE0(sched, , , remain__cpu); 1082 1083 #ifdef SMP 1084 if (td->td_flags & TDF_IDLETD) 1085 CPU_SET(PCPU_GET(cpuid), &idle_cpus_mask); 1086 #endif 1087 sched_lock.mtx_lock = (uintptr_t)td; 1088 td->td_oncpu = PCPU_GET(cpuid); 1089 MPASS(td->td_lock == &sched_lock); 1090 } 1091 1092 void 1093 sched_wakeup(struct thread *td) 1094 { 1095 struct td_sched *ts; 1096 1097 THREAD_LOCK_ASSERT(td, MA_OWNED); 1098 ts = td->td_sched; 1099 td->td_flags &= ~TDF_CANSWAP; 1100 if (ts->ts_slptime > 1) { 1101 updatepri(td); 1102 resetpriority(td); 1103 } 1104 td->td_slptick = 0; 1105 ts->ts_slptime = 0; 1106 ts->ts_slice = sched_slice; 1107 sched_add(td, SRQ_BORING); 1108 } 1109 1110 #ifdef SMP 1111 static int 1112 forward_wakeup(int cpunum) 1113 { 1114 struct pcpu *pc; 1115 cpuset_t dontuse, map, map2; 1116 u_int id, me; 1117 int iscpuset; 1118 1119 mtx_assert(&sched_lock, MA_OWNED); 1120 1121 CTR0(KTR_RUNQ, "forward_wakeup()"); 1122 1123 if ((!forward_wakeup_enabled) || 1124 (forward_wakeup_use_mask == 0 && forward_wakeup_use_loop == 0)) 1125 return (0); 1126 if (!smp_started || cold || panicstr) 1127 return (0); 1128 1129 forward_wakeups_requested++; 1130 1131 /* 1132 * Check the idle mask we received against what we calculated 1133 * before in the old version. 1134 */ 1135 me = PCPU_GET(cpuid); 1136 1137 /* Don't bother if we should be doing it ourself. */ 1138 if (CPU_ISSET(me, &idle_cpus_mask) && 1139 (cpunum == NOCPU || me == cpunum)) 1140 return (0); 1141 1142 CPU_SETOF(me, &dontuse); 1143 CPU_OR(&dontuse, &stopped_cpus); 1144 CPU_OR(&dontuse, &hlt_cpus_mask); 1145 CPU_ZERO(&map2); 1146 if (forward_wakeup_use_loop) { 1147 STAILQ_FOREACH(pc, &cpuhead, pc_allcpu) { 1148 id = pc->pc_cpuid; 1149 if (!CPU_ISSET(id, &dontuse) && 1150 pc->pc_curthread == pc->pc_idlethread) { 1151 CPU_SET(id, &map2); 1152 } 1153 } 1154 } 1155 1156 if (forward_wakeup_use_mask) { 1157 map = idle_cpus_mask; 1158 CPU_NAND(&map, &dontuse); 1159 1160 /* If they are both on, compare and use loop if different. */ 1161 if (forward_wakeup_use_loop) { 1162 if (CPU_CMP(&map, &map2)) { 1163 printf("map != map2, loop method preferred\n"); 1164 map = map2; 1165 } 1166 } 1167 } else { 1168 map = map2; 1169 } 1170 1171 /* If we only allow a specific CPU, then mask off all the others. */ 1172 if (cpunum != NOCPU) { 1173 KASSERT((cpunum <= mp_maxcpus),("forward_wakeup: bad cpunum.")); 1174 iscpuset = CPU_ISSET(cpunum, &map); 1175 if (iscpuset == 0) 1176 CPU_ZERO(&map); 1177 else 1178 CPU_SETOF(cpunum, &map); 1179 } 1180 if (!CPU_EMPTY(&map)) { 1181 forward_wakeups_delivered++; 1182 STAILQ_FOREACH(pc, &cpuhead, pc_allcpu) { 1183 id = pc->pc_cpuid; 1184 if (!CPU_ISSET(id, &map)) 1185 continue; 1186 if (cpu_idle_wakeup(pc->pc_cpuid)) 1187 CPU_CLR(id, &map); 1188 } 1189 if (!CPU_EMPTY(&map)) 1190 ipi_selected(map, IPI_AST); 1191 return (1); 1192 } 1193 if (cpunum == NOCPU) 1194 printf("forward_wakeup: Idle processor not found\n"); 1195 return (0); 1196 } 1197 1198 static void 1199 kick_other_cpu(int pri, int cpuid) 1200 { 1201 struct pcpu *pcpu; 1202 int cpri; 1203 1204 pcpu = pcpu_find(cpuid); 1205 if (CPU_ISSET(cpuid, &idle_cpus_mask)) { 1206 forward_wakeups_delivered++; 1207 if (!cpu_idle_wakeup(cpuid)) 1208 ipi_cpu(cpuid, IPI_AST); 1209 return; 1210 } 1211 1212 cpri = pcpu->pc_curthread->td_priority; 1213 if (pri >= cpri) 1214 return; 1215 1216 #if defined(IPI_PREEMPTION) && defined(PREEMPTION) 1217 #if !defined(FULL_PREEMPTION) 1218 if (pri <= PRI_MAX_ITHD) 1219 #endif /* ! FULL_PREEMPTION */ 1220 { 1221 ipi_cpu(cpuid, IPI_PREEMPT); 1222 return; 1223 } 1224 #endif /* defined(IPI_PREEMPTION) && defined(PREEMPTION) */ 1225 1226 pcpu->pc_curthread->td_flags |= TDF_NEEDRESCHED; 1227 ipi_cpu(cpuid, IPI_AST); 1228 return; 1229 } 1230 #endif /* SMP */ 1231 1232 #ifdef SMP 1233 static int 1234 sched_pickcpu(struct thread *td) 1235 { 1236 int best, cpu; 1237 1238 mtx_assert(&sched_lock, MA_OWNED); 1239 1240 if (THREAD_CAN_SCHED(td, td->td_lastcpu)) 1241 best = td->td_lastcpu; 1242 else 1243 best = NOCPU; 1244 CPU_FOREACH(cpu) { 1245 if (!THREAD_CAN_SCHED(td, cpu)) 1246 continue; 1247 1248 if (best == NOCPU) 1249 best = cpu; 1250 else if (runq_length[cpu] < runq_length[best]) 1251 best = cpu; 1252 } 1253 KASSERT(best != NOCPU, ("no valid CPUs")); 1254 1255 return (best); 1256 } 1257 #endif 1258 1259 void 1260 sched_add(struct thread *td, int flags) 1261 #ifdef SMP 1262 { 1263 cpuset_t tidlemsk; 1264 struct td_sched *ts; 1265 u_int cpu, cpuid; 1266 int forwarded = 0; 1267 int single_cpu = 0; 1268 1269 ts = td->td_sched; 1270 THREAD_LOCK_ASSERT(td, MA_OWNED); 1271 KASSERT((td->td_inhibitors == 0), 1272 ("sched_add: trying to run inhibited thread")); 1273 KASSERT((TD_CAN_RUN(td) || TD_IS_RUNNING(td)), 1274 ("sched_add: bad thread state")); 1275 KASSERT(td->td_flags & TDF_INMEM, 1276 ("sched_add: thread swapped out")); 1277 1278 KTR_STATE2(KTR_SCHED, "thread", sched_tdname(td), "runq add", 1279 "prio:%d", td->td_priority, KTR_ATTR_LINKED, 1280 sched_tdname(curthread)); 1281 KTR_POINT1(KTR_SCHED, "thread", sched_tdname(curthread), "wokeup", 1282 KTR_ATTR_LINKED, sched_tdname(td)); 1283 SDT_PROBE4(sched, , , enqueue, td, td->td_proc, NULL, 1284 flags & SRQ_PREEMPTED); 1285 1286 1287 /* 1288 * Now that the thread is moving to the run-queue, set the lock 1289 * to the scheduler's lock. 1290 */ 1291 if (td->td_lock != &sched_lock) { 1292 mtx_lock_spin(&sched_lock); 1293 thread_lock_set(td, &sched_lock); 1294 } 1295 TD_SET_RUNQ(td); 1296 1297 /* 1298 * If SMP is started and the thread is pinned or otherwise limited to 1299 * a specific set of CPUs, queue the thread to a per-CPU run queue. 1300 * Otherwise, queue the thread to the global run queue. 1301 * 1302 * If SMP has not yet been started we must use the global run queue 1303 * as per-CPU state may not be initialized yet and we may crash if we 1304 * try to access the per-CPU run queues. 1305 */ 1306 if (smp_started && (td->td_pinned != 0 || td->td_flags & TDF_BOUND || 1307 ts->ts_flags & TSF_AFFINITY)) { 1308 if (td->td_pinned != 0) 1309 cpu = td->td_lastcpu; 1310 else if (td->td_flags & TDF_BOUND) { 1311 /* Find CPU from bound runq. */ 1312 KASSERT(SKE_RUNQ_PCPU(ts), 1313 ("sched_add: bound td_sched not on cpu runq")); 1314 cpu = ts->ts_runq - &runq_pcpu[0]; 1315 } else 1316 /* Find a valid CPU for our cpuset */ 1317 cpu = sched_pickcpu(td); 1318 ts->ts_runq = &runq_pcpu[cpu]; 1319 single_cpu = 1; 1320 CTR3(KTR_RUNQ, 1321 "sched_add: Put td_sched:%p(td:%p) on cpu%d runq", ts, td, 1322 cpu); 1323 } else { 1324 CTR2(KTR_RUNQ, 1325 "sched_add: adding td_sched:%p (td:%p) to gbl runq", ts, 1326 td); 1327 cpu = NOCPU; 1328 ts->ts_runq = &runq; 1329 } 1330 1331 cpuid = PCPU_GET(cpuid); 1332 if (single_cpu && cpu != cpuid) { 1333 kick_other_cpu(td->td_priority, cpu); 1334 } else { 1335 if (!single_cpu) { 1336 tidlemsk = idle_cpus_mask; 1337 CPU_NAND(&tidlemsk, &hlt_cpus_mask); 1338 CPU_CLR(cpuid, &tidlemsk); 1339 1340 if (!CPU_ISSET(cpuid, &idle_cpus_mask) && 1341 ((flags & SRQ_INTR) == 0) && 1342 !CPU_EMPTY(&tidlemsk)) 1343 forwarded = forward_wakeup(cpu); 1344 } 1345 1346 if (!forwarded) { 1347 if ((flags & SRQ_YIELDING) == 0 && maybe_preempt(td)) 1348 return; 1349 else 1350 maybe_resched(td); 1351 } 1352 } 1353 1354 if ((td->td_flags & TDF_NOLOAD) == 0) 1355 sched_load_add(); 1356 runq_add(ts->ts_runq, td, flags); 1357 if (cpu != NOCPU) 1358 runq_length[cpu]++; 1359 } 1360 #else /* SMP */ 1361 { 1362 struct td_sched *ts; 1363 1364 ts = td->td_sched; 1365 THREAD_LOCK_ASSERT(td, MA_OWNED); 1366 KASSERT((td->td_inhibitors == 0), 1367 ("sched_add: trying to run inhibited thread")); 1368 KASSERT((TD_CAN_RUN(td) || TD_IS_RUNNING(td)), 1369 ("sched_add: bad thread state")); 1370 KASSERT(td->td_flags & TDF_INMEM, 1371 ("sched_add: thread swapped out")); 1372 KTR_STATE2(KTR_SCHED, "thread", sched_tdname(td), "runq add", 1373 "prio:%d", td->td_priority, KTR_ATTR_LINKED, 1374 sched_tdname(curthread)); 1375 KTR_POINT1(KTR_SCHED, "thread", sched_tdname(curthread), "wokeup", 1376 KTR_ATTR_LINKED, sched_tdname(td)); 1377 SDT_PROBE4(sched, , , enqueue, td, td->td_proc, NULL, 1378 flags & SRQ_PREEMPTED); 1379 1380 /* 1381 * Now that the thread is moving to the run-queue, set the lock 1382 * to the scheduler's lock. 1383 */ 1384 if (td->td_lock != &sched_lock) { 1385 mtx_lock_spin(&sched_lock); 1386 thread_lock_set(td, &sched_lock); 1387 } 1388 TD_SET_RUNQ(td); 1389 CTR2(KTR_RUNQ, "sched_add: adding td_sched:%p (td:%p) to runq", ts, td); 1390 ts->ts_runq = &runq; 1391 1392 /* 1393 * If we are yielding (on the way out anyhow) or the thread 1394 * being saved is US, then don't try be smart about preemption 1395 * or kicking off another CPU as it won't help and may hinder. 1396 * In the YIEDLING case, we are about to run whoever is being 1397 * put in the queue anyhow, and in the OURSELF case, we are 1398 * putting ourself on the run queue which also only happens 1399 * when we are about to yield. 1400 */ 1401 if ((flags & SRQ_YIELDING) == 0) { 1402 if (maybe_preempt(td)) 1403 return; 1404 } 1405 if ((td->td_flags & TDF_NOLOAD) == 0) 1406 sched_load_add(); 1407 runq_add(ts->ts_runq, td, flags); 1408 maybe_resched(td); 1409 } 1410 #endif /* SMP */ 1411 1412 void 1413 sched_rem(struct thread *td) 1414 { 1415 struct td_sched *ts; 1416 1417 ts = td->td_sched; 1418 KASSERT(td->td_flags & TDF_INMEM, 1419 ("sched_rem: thread swapped out")); 1420 KASSERT(TD_ON_RUNQ(td), 1421 ("sched_rem: thread not on run queue")); 1422 mtx_assert(&sched_lock, MA_OWNED); 1423 KTR_STATE2(KTR_SCHED, "thread", sched_tdname(td), "runq rem", 1424 "prio:%d", td->td_priority, KTR_ATTR_LINKED, 1425 sched_tdname(curthread)); 1426 SDT_PROBE3(sched, , , dequeue, td, td->td_proc, NULL); 1427 1428 if ((td->td_flags & TDF_NOLOAD) == 0) 1429 sched_load_rem(); 1430 #ifdef SMP 1431 if (ts->ts_runq != &runq) 1432 runq_length[ts->ts_runq - runq_pcpu]--; 1433 #endif 1434 runq_remove(ts->ts_runq, td); 1435 TD_SET_CAN_RUN(td); 1436 } 1437 1438 /* 1439 * Select threads to run. Note that running threads still consume a 1440 * slot. 1441 */ 1442 struct thread * 1443 sched_choose(void) 1444 { 1445 struct thread *td; 1446 struct runq *rq; 1447 1448 mtx_assert(&sched_lock, MA_OWNED); 1449 #ifdef SMP 1450 struct thread *tdcpu; 1451 1452 rq = &runq; 1453 td = runq_choose_fuzz(&runq, runq_fuzz); 1454 tdcpu = runq_choose(&runq_pcpu[PCPU_GET(cpuid)]); 1455 1456 if (td == NULL || 1457 (tdcpu != NULL && 1458 tdcpu->td_priority < td->td_priority)) { 1459 CTR2(KTR_RUNQ, "choosing td %p from pcpu runq %d", tdcpu, 1460 PCPU_GET(cpuid)); 1461 td = tdcpu; 1462 rq = &runq_pcpu[PCPU_GET(cpuid)]; 1463 } else { 1464 CTR1(KTR_RUNQ, "choosing td_sched %p from main runq", td); 1465 } 1466 1467 #else 1468 rq = &runq; 1469 td = runq_choose(&runq); 1470 #endif 1471 1472 if (td) { 1473 #ifdef SMP 1474 if (td == tdcpu) 1475 runq_length[PCPU_GET(cpuid)]--; 1476 #endif 1477 runq_remove(rq, td); 1478 td->td_flags |= TDF_DIDRUN; 1479 1480 KASSERT(td->td_flags & TDF_INMEM, 1481 ("sched_choose: thread swapped out")); 1482 return (td); 1483 } 1484 return (PCPU_GET(idlethread)); 1485 } 1486 1487 void 1488 sched_preempt(struct thread *td) 1489 { 1490 1491 SDT_PROBE2(sched, , , surrender, td, td->td_proc); 1492 thread_lock(td); 1493 if (td->td_critnest > 1) 1494 td->td_owepreempt = 1; 1495 else 1496 mi_switch(SW_INVOL | SW_PREEMPT | SWT_PREEMPT, NULL); 1497 thread_unlock(td); 1498 } 1499 1500 void 1501 sched_userret(struct thread *td) 1502 { 1503 /* 1504 * XXX we cheat slightly on the locking here to avoid locking in 1505 * the usual case. Setting td_priority here is essentially an 1506 * incomplete workaround for not setting it properly elsewhere. 1507 * Now that some interrupt handlers are threads, not setting it 1508 * properly elsewhere can clobber it in the window between setting 1509 * it here and returning to user mode, so don't waste time setting 1510 * it perfectly here. 1511 */ 1512 KASSERT((td->td_flags & TDF_BORROWING) == 0, 1513 ("thread with borrowed priority returning to userland")); 1514 if (td->td_priority != td->td_user_pri) { 1515 thread_lock(td); 1516 td->td_priority = td->td_user_pri; 1517 td->td_base_pri = td->td_user_pri; 1518 thread_unlock(td); 1519 } 1520 } 1521 1522 void 1523 sched_bind(struct thread *td, int cpu) 1524 { 1525 struct td_sched *ts; 1526 1527 THREAD_LOCK_ASSERT(td, MA_OWNED|MA_NOTRECURSED); 1528 KASSERT(td == curthread, ("sched_bind: can only bind curthread")); 1529 1530 ts = td->td_sched; 1531 1532 td->td_flags |= TDF_BOUND; 1533 #ifdef SMP 1534 ts->ts_runq = &runq_pcpu[cpu]; 1535 if (PCPU_GET(cpuid) == cpu) 1536 return; 1537 1538 mi_switch(SW_VOL, NULL); 1539 #endif 1540 } 1541 1542 void 1543 sched_unbind(struct thread* td) 1544 { 1545 THREAD_LOCK_ASSERT(td, MA_OWNED); 1546 KASSERT(td == curthread, ("sched_unbind: can only bind curthread")); 1547 td->td_flags &= ~TDF_BOUND; 1548 } 1549 1550 int 1551 sched_is_bound(struct thread *td) 1552 { 1553 THREAD_LOCK_ASSERT(td, MA_OWNED); 1554 return (td->td_flags & TDF_BOUND); 1555 } 1556 1557 void 1558 sched_relinquish(struct thread *td) 1559 { 1560 thread_lock(td); 1561 mi_switch(SW_VOL | SWT_RELINQUISH, NULL); 1562 thread_unlock(td); 1563 } 1564 1565 int 1566 sched_load(void) 1567 { 1568 return (sched_tdcnt); 1569 } 1570 1571 int 1572 sched_sizeof_proc(void) 1573 { 1574 return (sizeof(struct proc)); 1575 } 1576 1577 int 1578 sched_sizeof_thread(void) 1579 { 1580 return (sizeof(struct thread) + sizeof(struct td_sched)); 1581 } 1582 1583 fixpt_t 1584 sched_pctcpu(struct thread *td) 1585 { 1586 struct td_sched *ts; 1587 1588 THREAD_LOCK_ASSERT(td, MA_OWNED); 1589 ts = td->td_sched; 1590 return (ts->ts_pctcpu); 1591 } 1592 1593 #ifdef RACCT 1594 /* 1595 * Calculates the contribution to the thread cpu usage for the latest 1596 * (unfinished) second. 1597 */ 1598 fixpt_t 1599 sched_pctcpu_delta(struct thread *td) 1600 { 1601 struct td_sched *ts; 1602 fixpt_t delta; 1603 int realstathz; 1604 1605 THREAD_LOCK_ASSERT(td, MA_OWNED); 1606 ts = td->td_sched; 1607 delta = 0; 1608 realstathz = stathz ? stathz : hz; 1609 if (ts->ts_cpticks != 0) { 1610 #if (FSHIFT >= CCPU_SHIFT) 1611 delta = (realstathz == 100) 1612 ? ((fixpt_t) ts->ts_cpticks) << 1613 (FSHIFT - CCPU_SHIFT) : 1614 100 * (((fixpt_t) ts->ts_cpticks) 1615 << (FSHIFT - CCPU_SHIFT)) / realstathz; 1616 #else 1617 delta = ((FSCALE - ccpu) * 1618 (ts->ts_cpticks * 1619 FSCALE / realstathz)) >> FSHIFT; 1620 #endif 1621 } 1622 1623 return (delta); 1624 } 1625 #endif 1626 1627 u_int 1628 sched_estcpu(struct thread *td) 1629 { 1630 1631 return (td->td_sched->ts_estcpu); 1632 } 1633 1634 /* 1635 * The actual idle process. 1636 */ 1637 void 1638 sched_idletd(void *dummy) 1639 { 1640 struct pcpuidlestat *stat; 1641 1642 THREAD_NO_SLEEPING(); 1643 stat = DPCPU_PTR(idlestat); 1644 for (;;) { 1645 mtx_assert(&Giant, MA_NOTOWNED); 1646 1647 while (sched_runnable() == 0) { 1648 cpu_idle(stat->idlecalls + stat->oldidlecalls > 64); 1649 stat->idlecalls++; 1650 } 1651 1652 mtx_lock_spin(&sched_lock); 1653 mi_switch(SW_VOL | SWT_IDLE, NULL); 1654 mtx_unlock_spin(&sched_lock); 1655 } 1656 } 1657 1658 /* 1659 * A CPU is entering for the first time or a thread is exiting. 1660 */ 1661 void 1662 sched_throw(struct thread *td) 1663 { 1664 /* 1665 * Correct spinlock nesting. The idle thread context that we are 1666 * borrowing was created so that it would start out with a single 1667 * spin lock (sched_lock) held in fork_trampoline(). Since we've 1668 * explicitly acquired locks in this function, the nesting count 1669 * is now 2 rather than 1. Since we are nested, calling 1670 * spinlock_exit() will simply adjust the counts without allowing 1671 * spin lock using code to interrupt us. 1672 */ 1673 if (td == NULL) { 1674 mtx_lock_spin(&sched_lock); 1675 spinlock_exit(); 1676 PCPU_SET(switchtime, cpu_ticks()); 1677 PCPU_SET(switchticks, ticks); 1678 } else { 1679 lock_profile_release_lock(&sched_lock.lock_object); 1680 MPASS(td->td_lock == &sched_lock); 1681 td->td_lastcpu = td->td_oncpu; 1682 td->td_oncpu = NOCPU; 1683 } 1684 mtx_assert(&sched_lock, MA_OWNED); 1685 KASSERT(curthread->td_md.md_spinlock_count == 1, ("invalid count")); 1686 cpu_throw(td, choosethread()); /* doesn't return */ 1687 } 1688 1689 void 1690 sched_fork_exit(struct thread *td) 1691 { 1692 1693 /* 1694 * Finish setting up thread glue so that it begins execution in a 1695 * non-nested critical section with sched_lock held but not recursed. 1696 */ 1697 td->td_oncpu = PCPU_GET(cpuid); 1698 sched_lock.mtx_lock = (uintptr_t)td; 1699 lock_profile_obtain_lock_success(&sched_lock.lock_object, 1700 0, 0, __FILE__, __LINE__); 1701 THREAD_LOCK_ASSERT(td, MA_OWNED | MA_NOTRECURSED); 1702 } 1703 1704 char * 1705 sched_tdname(struct thread *td) 1706 { 1707 #ifdef KTR 1708 struct td_sched *ts; 1709 1710 ts = td->td_sched; 1711 if (ts->ts_name[0] == '\0') 1712 snprintf(ts->ts_name, sizeof(ts->ts_name), 1713 "%s tid %d", td->td_name, td->td_tid); 1714 return (ts->ts_name); 1715 #else 1716 return (td->td_name); 1717 #endif 1718 } 1719 1720 #ifdef KTR 1721 void 1722 sched_clear_tdname(struct thread *td) 1723 { 1724 struct td_sched *ts; 1725 1726 ts = td->td_sched; 1727 ts->ts_name[0] = '\0'; 1728 } 1729 #endif 1730 1731 void 1732 sched_affinity(struct thread *td) 1733 { 1734 #ifdef SMP 1735 struct td_sched *ts; 1736 int cpu; 1737 1738 THREAD_LOCK_ASSERT(td, MA_OWNED); 1739 1740 /* 1741 * Set the TSF_AFFINITY flag if there is at least one CPU this 1742 * thread can't run on. 1743 */ 1744 ts = td->td_sched; 1745 ts->ts_flags &= ~TSF_AFFINITY; 1746 CPU_FOREACH(cpu) { 1747 if (!THREAD_CAN_SCHED(td, cpu)) { 1748 ts->ts_flags |= TSF_AFFINITY; 1749 break; 1750 } 1751 } 1752 1753 /* 1754 * If this thread can run on all CPUs, nothing else to do. 1755 */ 1756 if (!(ts->ts_flags & TSF_AFFINITY)) 1757 return; 1758 1759 /* Pinned threads and bound threads should be left alone. */ 1760 if (td->td_pinned != 0 || td->td_flags & TDF_BOUND) 1761 return; 1762 1763 switch (td->td_state) { 1764 case TDS_RUNQ: 1765 /* 1766 * If we are on a per-CPU runqueue that is in the set, 1767 * then nothing needs to be done. 1768 */ 1769 if (ts->ts_runq != &runq && 1770 THREAD_CAN_SCHED(td, ts->ts_runq - runq_pcpu)) 1771 return; 1772 1773 /* Put this thread on a valid per-CPU runqueue. */ 1774 sched_rem(td); 1775 sched_add(td, SRQ_BORING); 1776 break; 1777 case TDS_RUNNING: 1778 /* 1779 * See if our current CPU is in the set. If not, force a 1780 * context switch. 1781 */ 1782 if (THREAD_CAN_SCHED(td, td->td_oncpu)) 1783 return; 1784 1785 td->td_flags |= TDF_NEEDRESCHED; 1786 if (td != curthread) 1787 ipi_cpu(cpu, IPI_AST); 1788 break; 1789 default: 1790 break; 1791 } 1792 #endif 1793 } 1794