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 * 3. 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_assert(sizeof(struct thread) + sizeof(struct td_sched) <= 121 sizeof(struct thread0_storage), 122 "increase struct thread0_storage.t0st_sched size"); 123 124 static struct mtx sched_lock; 125 126 static int realstathz = 127; /* stathz is sometimes 0 and run off of hz. */ 127 static int sched_tdcnt; /* Total runnable threads in the system. */ 128 static int sched_slice = 12; /* Thread run time before rescheduling. */ 129 130 static void setup_runqs(void); 131 static void schedcpu(void); 132 static void schedcpu_thread(void); 133 static void sched_priority(struct thread *td, u_char prio); 134 static void sched_setup(void *dummy); 135 static void maybe_resched(struct thread *td); 136 static void updatepri(struct thread *td); 137 static void resetpriority(struct thread *td); 138 static void resetpriority_thread(struct thread *td); 139 #ifdef SMP 140 static int sched_pickcpu(struct thread *td); 141 static int forward_wakeup(int cpunum); 142 static void kick_other_cpu(int pri, int cpuid); 143 #endif 144 145 static struct kproc_desc sched_kp = { 146 "schedcpu", 147 schedcpu_thread, 148 NULL 149 }; 150 SYSINIT(schedcpu, SI_SUB_LAST, SI_ORDER_FIRST, kproc_start, 151 &sched_kp); 152 SYSINIT(sched_setup, SI_SUB_RUN_QUEUE, SI_ORDER_FIRST, sched_setup, NULL); 153 154 static void sched_initticks(void *dummy); 155 SYSINIT(sched_initticks, SI_SUB_CLOCKS, SI_ORDER_THIRD, sched_initticks, 156 NULL); 157 158 /* 159 * Global run queue. 160 */ 161 static struct runq runq; 162 163 #ifdef SMP 164 /* 165 * Per-CPU run queues 166 */ 167 static struct runq runq_pcpu[MAXCPU]; 168 long runq_length[MAXCPU]; 169 170 static cpuset_t idle_cpus_mask; 171 #endif 172 173 struct pcpuidlestat { 174 u_int idlecalls; 175 u_int oldidlecalls; 176 }; 177 static DPCPU_DEFINE(struct pcpuidlestat, idlestat); 178 179 static void 180 setup_runqs(void) 181 { 182 #ifdef SMP 183 int i; 184 185 for (i = 0; i < MAXCPU; ++i) 186 runq_init(&runq_pcpu[i]); 187 #endif 188 189 runq_init(&runq); 190 } 191 192 static int 193 sysctl_kern_quantum(SYSCTL_HANDLER_ARGS) 194 { 195 int error, new_val, period; 196 197 period = 1000000 / realstathz; 198 new_val = period * sched_slice; 199 error = sysctl_handle_int(oidp, &new_val, 0, req); 200 if (error != 0 || req->newptr == NULL) 201 return (error); 202 if (new_val <= 0) 203 return (EINVAL); 204 sched_slice = imax(1, (new_val + period / 2) / period); 205 hogticks = imax(1, (2 * hz * sched_slice + realstathz / 2) / 206 realstathz); 207 return (0); 208 } 209 210 SYSCTL_NODE(_kern, OID_AUTO, sched, CTLFLAG_RD, 0, "Scheduler"); 211 212 SYSCTL_STRING(_kern_sched, OID_AUTO, name, CTLFLAG_RD, "4BSD", 0, 213 "Scheduler name"); 214 SYSCTL_PROC(_kern_sched, OID_AUTO, quantum, CTLTYPE_INT | CTLFLAG_RW, 215 NULL, 0, sysctl_kern_quantum, "I", 216 "Quantum for timeshare threads in microseconds"); 217 SYSCTL_INT(_kern_sched, OID_AUTO, slice, CTLFLAG_RW, &sched_slice, 0, 218 "Quantum for timeshare threads in stathz ticks"); 219 #ifdef SMP 220 /* Enable forwarding of wakeups to all other cpus */ 221 static SYSCTL_NODE(_kern_sched, OID_AUTO, ipiwakeup, CTLFLAG_RD, NULL, 222 "Kernel SMP"); 223 224 static int runq_fuzz = 1; 225 SYSCTL_INT(_kern_sched, OID_AUTO, runq_fuzz, CTLFLAG_RW, &runq_fuzz, 0, ""); 226 227 static int forward_wakeup_enabled = 1; 228 SYSCTL_INT(_kern_sched_ipiwakeup, OID_AUTO, enabled, CTLFLAG_RW, 229 &forward_wakeup_enabled, 0, 230 "Forwarding of wakeup to idle CPUs"); 231 232 static int forward_wakeups_requested = 0; 233 SYSCTL_INT(_kern_sched_ipiwakeup, OID_AUTO, requested, CTLFLAG_RD, 234 &forward_wakeups_requested, 0, 235 "Requests for Forwarding of wakeup to idle CPUs"); 236 237 static int forward_wakeups_delivered = 0; 238 SYSCTL_INT(_kern_sched_ipiwakeup, OID_AUTO, delivered, CTLFLAG_RD, 239 &forward_wakeups_delivered, 0, 240 "Completed Forwarding of wakeup to idle CPUs"); 241 242 static int forward_wakeup_use_mask = 1; 243 SYSCTL_INT(_kern_sched_ipiwakeup, OID_AUTO, usemask, CTLFLAG_RW, 244 &forward_wakeup_use_mask, 0, 245 "Use the mask of idle cpus"); 246 247 static int forward_wakeup_use_loop = 0; 248 SYSCTL_INT(_kern_sched_ipiwakeup, OID_AUTO, useloop, CTLFLAG_RW, 249 &forward_wakeup_use_loop, 0, 250 "Use a loop to find idle cpus"); 251 252 #endif 253 #if 0 254 static int sched_followon = 0; 255 SYSCTL_INT(_kern_sched, OID_AUTO, followon, CTLFLAG_RW, 256 &sched_followon, 0, 257 "allow threads to share a quantum"); 258 #endif 259 260 SDT_PROVIDER_DEFINE(sched); 261 262 SDT_PROBE_DEFINE3(sched, , , change__pri, "struct thread *", 263 "struct proc *", "uint8_t"); 264 SDT_PROBE_DEFINE3(sched, , , dequeue, "struct thread *", 265 "struct proc *", "void *"); 266 SDT_PROBE_DEFINE4(sched, , , enqueue, "struct thread *", 267 "struct proc *", "void *", "int"); 268 SDT_PROBE_DEFINE4(sched, , , lend__pri, "struct thread *", 269 "struct proc *", "uint8_t", "struct thread *"); 270 SDT_PROBE_DEFINE2(sched, , , load__change, "int", "int"); 271 SDT_PROBE_DEFINE2(sched, , , off__cpu, "struct thread *", 272 "struct proc *"); 273 SDT_PROBE_DEFINE(sched, , , on__cpu); 274 SDT_PROBE_DEFINE(sched, , , remain__cpu); 275 SDT_PROBE_DEFINE2(sched, , , surrender, "struct thread *", 276 "struct proc *"); 277 278 static __inline void 279 sched_load_add(void) 280 { 281 282 sched_tdcnt++; 283 KTR_COUNTER0(KTR_SCHED, "load", "global load", sched_tdcnt); 284 SDT_PROBE2(sched, , , load__change, NOCPU, sched_tdcnt); 285 } 286 287 static __inline void 288 sched_load_rem(void) 289 { 290 291 sched_tdcnt--; 292 KTR_COUNTER0(KTR_SCHED, "load", "global load", sched_tdcnt); 293 SDT_PROBE2(sched, , , load__change, NOCPU, sched_tdcnt); 294 } 295 /* 296 * Arrange to reschedule if necessary, taking the priorities and 297 * schedulers into account. 298 */ 299 static void 300 maybe_resched(struct thread *td) 301 { 302 303 THREAD_LOCK_ASSERT(td, MA_OWNED); 304 if (td->td_priority < curthread->td_priority) 305 curthread->td_flags |= TDF_NEEDRESCHED; 306 } 307 308 /* 309 * This function is called when a thread is about to be put on run queue 310 * because it has been made runnable or its priority has been adjusted. It 311 * determines if the new thread should preempt the current thread. If so, 312 * it sets td_owepreempt to request a preemption. 313 */ 314 int 315 maybe_preempt(struct thread *td) 316 { 317 #ifdef PREEMPTION 318 struct thread *ctd; 319 int cpri, pri; 320 321 /* 322 * The new thread should not preempt the current thread if any of the 323 * following conditions are true: 324 * 325 * - The kernel is in the throes of crashing (panicstr). 326 * - The current thread has a higher (numerically lower) or 327 * equivalent priority. Note that this prevents curthread from 328 * trying to preempt to itself. 329 * - The current thread has an inhibitor set or is in the process of 330 * exiting. In this case, the current thread is about to switch 331 * out anyways, so there's no point in preempting. If we did, 332 * the current thread would not be properly resumed as well, so 333 * just avoid that whole landmine. 334 * - If the new thread's priority is not a realtime priority and 335 * the current thread's priority is not an idle priority and 336 * FULL_PREEMPTION is disabled. 337 * 338 * If all of these conditions are false, but the current thread is in 339 * a nested critical section, then we have to defer the preemption 340 * until we exit the critical section. Otherwise, switch immediately 341 * to the new thread. 342 */ 343 ctd = curthread; 344 THREAD_LOCK_ASSERT(td, MA_OWNED); 345 KASSERT((td->td_inhibitors == 0), 346 ("maybe_preempt: trying to run inhibited thread")); 347 pri = td->td_priority; 348 cpri = ctd->td_priority; 349 if (panicstr != NULL || pri >= cpri /* || dumping */ || 350 TD_IS_INHIBITED(ctd)) 351 return (0); 352 #ifndef FULL_PREEMPTION 353 if (pri > PRI_MAX_ITHD && cpri < PRI_MIN_IDLE) 354 return (0); 355 #endif 356 357 CTR0(KTR_PROC, "maybe_preempt: scheduling preemption"); 358 ctd->td_owepreempt = 1; 359 return (1); 360 #else 361 return (0); 362 #endif 363 } 364 365 /* 366 * Constants for digital decay and forget: 367 * 90% of (ts_estcpu) usage in 5 * loadav time 368 * 95% of (ts_pctcpu) usage in 60 seconds (load insensitive) 369 * Note that, as ps(1) mentions, this can let percentages 370 * total over 100% (I've seen 137.9% for 3 processes). 371 * 372 * Note that schedclock() updates ts_estcpu and p_cpticks asynchronously. 373 * 374 * We wish to decay away 90% of ts_estcpu in (5 * loadavg) seconds. 375 * That is, the system wants to compute a value of decay such 376 * that the following for loop: 377 * for (i = 0; i < (5 * loadavg); i++) 378 * ts_estcpu *= decay; 379 * will compute 380 * ts_estcpu *= 0.1; 381 * for all values of loadavg: 382 * 383 * Mathematically this loop can be expressed by saying: 384 * decay ** (5 * loadavg) ~= .1 385 * 386 * The system computes decay as: 387 * decay = (2 * loadavg) / (2 * loadavg + 1) 388 * 389 * We wish to prove that the system's computation of decay 390 * will always fulfill the equation: 391 * decay ** (5 * loadavg) ~= .1 392 * 393 * If we compute b as: 394 * b = 2 * loadavg 395 * then 396 * decay = b / (b + 1) 397 * 398 * We now need to prove two things: 399 * 1) Given factor ** (5 * loadavg) ~= .1, prove factor == b/(b+1) 400 * 2) Given b/(b+1) ** power ~= .1, prove power == (5 * loadavg) 401 * 402 * Facts: 403 * For x close to zero, exp(x) =~ 1 + x, since 404 * exp(x) = 0! + x**1/1! + x**2/2! + ... . 405 * therefore exp(-1/b) =~ 1 - (1/b) = (b-1)/b. 406 * For x close to zero, ln(1+x) =~ x, since 407 * ln(1+x) = x - x**2/2 + x**3/3 - ... -1 < x < 1 408 * therefore ln(b/(b+1)) = ln(1 - 1/(b+1)) =~ -1/(b+1). 409 * ln(.1) =~ -2.30 410 * 411 * Proof of (1): 412 * Solve (factor)**(power) =~ .1 given power (5*loadav): 413 * solving for factor, 414 * ln(factor) =~ (-2.30/5*loadav), or 415 * factor =~ exp(-1/((5/2.30)*loadav)) =~ exp(-1/(2*loadav)) = 416 * exp(-1/b) =~ (b-1)/b =~ b/(b+1). QED 417 * 418 * Proof of (2): 419 * Solve (factor)**(power) =~ .1 given factor == (b/(b+1)): 420 * solving for power, 421 * power*ln(b/(b+1)) =~ -2.30, or 422 * power =~ 2.3 * (b + 1) = 4.6*loadav + 2.3 =~ 5*loadav. QED 423 * 424 * Actual power values for the implemented algorithm are as follows: 425 * loadav: 1 2 3 4 426 * power: 5.68 10.32 14.94 19.55 427 */ 428 429 /* calculations for digital decay to forget 90% of usage in 5*loadav sec */ 430 #define loadfactor(loadav) (2 * (loadav)) 431 #define decay_cpu(loadfac, cpu) (((loadfac) * (cpu)) / ((loadfac) + FSCALE)) 432 433 /* decay 95% of `ts_pctcpu' in 60 seconds; see CCPU_SHIFT before changing */ 434 static fixpt_t ccpu = 0.95122942450071400909 * FSCALE; /* exp(-1/20) */ 435 SYSCTL_UINT(_kern, OID_AUTO, ccpu, CTLFLAG_RD, &ccpu, 0, ""); 436 437 /* 438 * If `ccpu' is not equal to `exp(-1/20)' and you still want to use the 439 * faster/more-accurate formula, you'll have to estimate CCPU_SHIFT below 440 * and possibly adjust FSHIFT in "param.h" so that (FSHIFT >= CCPU_SHIFT). 441 * 442 * To estimate CCPU_SHIFT for exp(-1/20), the following formula was used: 443 * 1 - exp(-1/20) ~= 0.0487 ~= 0.0488 == 1 (fixed pt, *11* bits). 444 * 445 * If you don't want to bother with the faster/more-accurate formula, you 446 * can set CCPU_SHIFT to (FSHIFT + 1) which will use a slower/less-accurate 447 * (more general) method of calculating the %age of CPU used by a process. 448 */ 449 #define CCPU_SHIFT 11 450 451 /* 452 * Recompute process priorities, every hz ticks. 453 * MP-safe, called without the Giant mutex. 454 */ 455 /* ARGSUSED */ 456 static void 457 schedcpu(void) 458 { 459 register fixpt_t loadfac = loadfactor(averunnable.ldavg[0]); 460 struct thread *td; 461 struct proc *p; 462 struct td_sched *ts; 463 int awake; 464 465 sx_slock(&allproc_lock); 466 FOREACH_PROC_IN_SYSTEM(p) { 467 PROC_LOCK(p); 468 if (p->p_state == PRS_NEW) { 469 PROC_UNLOCK(p); 470 continue; 471 } 472 FOREACH_THREAD_IN_PROC(p, td) { 473 awake = 0; 474 ts = td_get_sched(td); 475 thread_lock(td); 476 /* 477 * Increment sleep time (if sleeping). We 478 * ignore overflow, as above. 479 */ 480 /* 481 * The td_sched slptimes are not touched in wakeup 482 * because the thread may not HAVE everything in 483 * memory? XXX I think this is out of date. 484 */ 485 if (TD_ON_RUNQ(td)) { 486 awake = 1; 487 td->td_flags &= ~TDF_DIDRUN; 488 } else if (TD_IS_RUNNING(td)) { 489 awake = 1; 490 /* Do not clear TDF_DIDRUN */ 491 } else if (td->td_flags & TDF_DIDRUN) { 492 awake = 1; 493 td->td_flags &= ~TDF_DIDRUN; 494 } 495 496 /* 497 * ts_pctcpu is only for ps and ttyinfo(). 498 */ 499 ts->ts_pctcpu = (ts->ts_pctcpu * ccpu) >> FSHIFT; 500 /* 501 * If the td_sched has been idle the entire second, 502 * stop recalculating its priority until 503 * it wakes up. 504 */ 505 if (ts->ts_cpticks != 0) { 506 #if (FSHIFT >= CCPU_SHIFT) 507 ts->ts_pctcpu += (realstathz == 100) 508 ? ((fixpt_t) ts->ts_cpticks) << 509 (FSHIFT - CCPU_SHIFT) : 510 100 * (((fixpt_t) ts->ts_cpticks) 511 << (FSHIFT - CCPU_SHIFT)) / realstathz; 512 #else 513 ts->ts_pctcpu += ((FSCALE - ccpu) * 514 (ts->ts_cpticks * 515 FSCALE / realstathz)) >> FSHIFT; 516 #endif 517 ts->ts_cpticks = 0; 518 } 519 /* 520 * If there are ANY running threads in this process, 521 * then don't count it as sleeping. 522 * XXX: this is broken. 523 */ 524 if (awake) { 525 if (ts->ts_slptime > 1) { 526 /* 527 * In an ideal world, this should not 528 * happen, because whoever woke us 529 * up from the long sleep should have 530 * unwound the slptime and reset our 531 * priority before we run at the stale 532 * priority. Should KASSERT at some 533 * point when all the cases are fixed. 534 */ 535 updatepri(td); 536 } 537 ts->ts_slptime = 0; 538 } else 539 ts->ts_slptime++; 540 if (ts->ts_slptime > 1) { 541 thread_unlock(td); 542 continue; 543 } 544 ts->ts_estcpu = decay_cpu(loadfac, ts->ts_estcpu); 545 resetpriority(td); 546 resetpriority_thread(td); 547 thread_unlock(td); 548 } 549 PROC_UNLOCK(p); 550 } 551 sx_sunlock(&allproc_lock); 552 } 553 554 /* 555 * Main loop for a kthread that executes schedcpu once a second. 556 */ 557 static void 558 schedcpu_thread(void) 559 { 560 561 for (;;) { 562 schedcpu(); 563 pause("-", hz); 564 } 565 } 566 567 /* 568 * Recalculate the priority of a process after it has slept for a while. 569 * For all load averages >= 1 and max ts_estcpu of 255, sleeping for at 570 * least six times the loadfactor will decay ts_estcpu to zero. 571 */ 572 static void 573 updatepri(struct thread *td) 574 { 575 struct td_sched *ts; 576 fixpt_t loadfac; 577 unsigned int newcpu; 578 579 ts = td_get_sched(td); 580 loadfac = loadfactor(averunnable.ldavg[0]); 581 if (ts->ts_slptime > 5 * loadfac) 582 ts->ts_estcpu = 0; 583 else { 584 newcpu = ts->ts_estcpu; 585 ts->ts_slptime--; /* was incremented in schedcpu() */ 586 while (newcpu && --ts->ts_slptime) 587 newcpu = decay_cpu(loadfac, newcpu); 588 ts->ts_estcpu = newcpu; 589 } 590 } 591 592 /* 593 * Compute the priority of a process when running in user mode. 594 * Arrange to reschedule if the resulting priority is better 595 * than that of the current process. 596 */ 597 static void 598 resetpriority(struct thread *td) 599 { 600 u_int newpriority; 601 602 if (td->td_pri_class != PRI_TIMESHARE) 603 return; 604 newpriority = PUSER + 605 td_get_sched(td)->ts_estcpu / INVERSE_ESTCPU_WEIGHT + 606 NICE_WEIGHT * (td->td_proc->p_nice - PRIO_MIN); 607 newpriority = min(max(newpriority, PRI_MIN_TIMESHARE), 608 PRI_MAX_TIMESHARE); 609 sched_user_prio(td, newpriority); 610 } 611 612 /* 613 * Update the thread's priority when the associated process's user 614 * priority changes. 615 */ 616 static void 617 resetpriority_thread(struct thread *td) 618 { 619 620 /* Only change threads with a time sharing user priority. */ 621 if (td->td_priority < PRI_MIN_TIMESHARE || 622 td->td_priority > PRI_MAX_TIMESHARE) 623 return; 624 625 /* XXX the whole needresched thing is broken, but not silly. */ 626 maybe_resched(td); 627 628 sched_prio(td, td->td_user_pri); 629 } 630 631 /* ARGSUSED */ 632 static void 633 sched_setup(void *dummy) 634 { 635 636 setup_runqs(); 637 638 /* Account for thread0. */ 639 sched_load_add(); 640 } 641 642 /* 643 * This routine determines time constants after stathz and hz are setup. 644 */ 645 static void 646 sched_initticks(void *dummy) 647 { 648 649 realstathz = stathz ? stathz : hz; 650 sched_slice = realstathz / 10; /* ~100ms */ 651 hogticks = imax(1, (2 * hz * sched_slice + realstathz / 2) / 652 realstathz); 653 } 654 655 /* External interfaces start here */ 656 657 /* 658 * Very early in the boot some setup of scheduler-specific 659 * parts of proc0 and of some scheduler resources needs to be done. 660 * Called from: 661 * proc0_init() 662 */ 663 void 664 schedinit(void) 665 { 666 667 /* 668 * Set up the scheduler specific parts of thread0. 669 */ 670 thread0.td_lock = &sched_lock; 671 td_get_sched(&thread0)->ts_slice = sched_slice; 672 mtx_init(&sched_lock, "sched lock", NULL, MTX_SPIN | MTX_RECURSE); 673 } 674 675 int 676 sched_runnable(void) 677 { 678 #ifdef SMP 679 return runq_check(&runq) + runq_check(&runq_pcpu[PCPU_GET(cpuid)]); 680 #else 681 return runq_check(&runq); 682 #endif 683 } 684 685 int 686 sched_rr_interval(void) 687 { 688 689 /* Convert sched_slice from stathz to hz. */ 690 return (imax(1, (sched_slice * hz + realstathz / 2) / realstathz)); 691 } 692 693 /* 694 * We adjust the priority of the current process. The priority of a 695 * process gets worse as it accumulates CPU time. The cpu usage 696 * estimator (ts_estcpu) is increased here. resetpriority() will 697 * compute a different priority each time ts_estcpu increases by 698 * INVERSE_ESTCPU_WEIGHT (until PRI_MAX_TIMESHARE is reached). The 699 * cpu usage estimator ramps up quite quickly when the process is 700 * running (linearly), and decays away exponentially, at a rate which 701 * is proportionally slower when the system is busy. The basic 702 * principle is that the system will 90% forget that the process used 703 * a lot of CPU time in 5 * loadav seconds. This causes the system to 704 * favor processes which haven't run much recently, and to round-robin 705 * among other processes. 706 */ 707 void 708 sched_clock(struct thread *td) 709 { 710 struct pcpuidlestat *stat; 711 struct td_sched *ts; 712 713 THREAD_LOCK_ASSERT(td, MA_OWNED); 714 ts = td_get_sched(td); 715 716 ts->ts_cpticks++; 717 ts->ts_estcpu = ESTCPULIM(ts->ts_estcpu + 1); 718 if ((ts->ts_estcpu % INVERSE_ESTCPU_WEIGHT) == 0) { 719 resetpriority(td); 720 resetpriority_thread(td); 721 } 722 723 /* 724 * Force a context switch if the current thread has used up a full 725 * time slice (default is 100ms). 726 */ 727 if (!TD_IS_IDLETHREAD(td) && --ts->ts_slice <= 0) { 728 ts->ts_slice = sched_slice; 729 td->td_flags |= TDF_NEEDRESCHED | TDF_SLICEEND; 730 } 731 732 stat = DPCPU_PTR(idlestat); 733 stat->oldidlecalls = stat->idlecalls; 734 stat->idlecalls = 0; 735 } 736 737 /* 738 * Charge child's scheduling CPU usage to parent. 739 */ 740 void 741 sched_exit(struct proc *p, struct thread *td) 742 { 743 744 KTR_STATE1(KTR_SCHED, "thread", sched_tdname(td), "proc exit", 745 "prio:%d", td->td_priority); 746 747 PROC_LOCK_ASSERT(p, MA_OWNED); 748 sched_exit_thread(FIRST_THREAD_IN_PROC(p), td); 749 } 750 751 void 752 sched_exit_thread(struct thread *td, struct thread *child) 753 { 754 755 KTR_STATE1(KTR_SCHED, "thread", sched_tdname(child), "exit", 756 "prio:%d", child->td_priority); 757 thread_lock(td); 758 td_get_sched(td)->ts_estcpu = ESTCPULIM(td_get_sched(td)->ts_estcpu + 759 td_get_sched(child)->ts_estcpu); 760 thread_unlock(td); 761 thread_lock(child); 762 if ((child->td_flags & TDF_NOLOAD) == 0) 763 sched_load_rem(); 764 thread_unlock(child); 765 } 766 767 void 768 sched_fork(struct thread *td, struct thread *childtd) 769 { 770 sched_fork_thread(td, childtd); 771 } 772 773 void 774 sched_fork_thread(struct thread *td, struct thread *childtd) 775 { 776 struct td_sched *ts, *tsc; 777 778 childtd->td_oncpu = NOCPU; 779 childtd->td_lastcpu = NOCPU; 780 childtd->td_lock = &sched_lock; 781 childtd->td_cpuset = cpuset_ref(td->td_cpuset); 782 childtd->td_priority = childtd->td_base_pri; 783 ts = td_get_sched(childtd); 784 bzero(ts, sizeof(*ts)); 785 tsc = td_get_sched(td); 786 ts->ts_estcpu = tsc->ts_estcpu; 787 ts->ts_flags |= (tsc->ts_flags & TSF_AFFINITY); 788 ts->ts_slice = 1; 789 } 790 791 void 792 sched_nice(struct proc *p, int nice) 793 { 794 struct thread *td; 795 796 PROC_LOCK_ASSERT(p, MA_OWNED); 797 p->p_nice = nice; 798 FOREACH_THREAD_IN_PROC(p, td) { 799 thread_lock(td); 800 resetpriority(td); 801 resetpriority_thread(td); 802 thread_unlock(td); 803 } 804 } 805 806 void 807 sched_class(struct thread *td, int class) 808 { 809 THREAD_LOCK_ASSERT(td, MA_OWNED); 810 td->td_pri_class = class; 811 } 812 813 /* 814 * Adjust the priority of a thread. 815 */ 816 static void 817 sched_priority(struct thread *td, u_char prio) 818 { 819 820 821 KTR_POINT3(KTR_SCHED, "thread", sched_tdname(td), "priority change", 822 "prio:%d", td->td_priority, "new prio:%d", prio, KTR_ATTR_LINKED, 823 sched_tdname(curthread)); 824 SDT_PROBE3(sched, , , change__pri, td, td->td_proc, prio); 825 if (td != curthread && prio > td->td_priority) { 826 KTR_POINT3(KTR_SCHED, "thread", sched_tdname(curthread), 827 "lend prio", "prio:%d", td->td_priority, "new prio:%d", 828 prio, KTR_ATTR_LINKED, sched_tdname(td)); 829 SDT_PROBE4(sched, , , lend__pri, td, td->td_proc, prio, 830 curthread); 831 } 832 THREAD_LOCK_ASSERT(td, MA_OWNED); 833 if (td->td_priority == prio) 834 return; 835 td->td_priority = prio; 836 if (TD_ON_RUNQ(td) && td->td_rqindex != (prio / RQ_PPQ)) { 837 sched_rem(td); 838 sched_add(td, SRQ_BORING); 839 } 840 } 841 842 /* 843 * Update a thread's priority when it is lent another thread's 844 * priority. 845 */ 846 void 847 sched_lend_prio(struct thread *td, u_char prio) 848 { 849 850 td->td_flags |= TDF_BORROWING; 851 sched_priority(td, prio); 852 } 853 854 /* 855 * Restore a thread's priority when priority propagation is 856 * over. The prio argument is the minimum priority the thread 857 * needs to have to satisfy other possible priority lending 858 * requests. If the thread's regulary priority is less 859 * important than prio the thread will keep a priority boost 860 * of prio. 861 */ 862 void 863 sched_unlend_prio(struct thread *td, u_char prio) 864 { 865 u_char base_pri; 866 867 if (td->td_base_pri >= PRI_MIN_TIMESHARE && 868 td->td_base_pri <= PRI_MAX_TIMESHARE) 869 base_pri = td->td_user_pri; 870 else 871 base_pri = td->td_base_pri; 872 if (prio >= base_pri) { 873 td->td_flags &= ~TDF_BORROWING; 874 sched_prio(td, base_pri); 875 } else 876 sched_lend_prio(td, prio); 877 } 878 879 void 880 sched_prio(struct thread *td, u_char prio) 881 { 882 u_char oldprio; 883 884 /* First, update the base priority. */ 885 td->td_base_pri = prio; 886 887 /* 888 * If the thread is borrowing another thread's priority, don't ever 889 * lower the priority. 890 */ 891 if (td->td_flags & TDF_BORROWING && td->td_priority < prio) 892 return; 893 894 /* Change the real priority. */ 895 oldprio = td->td_priority; 896 sched_priority(td, prio); 897 898 /* 899 * If the thread is on a turnstile, then let the turnstile update 900 * its state. 901 */ 902 if (TD_ON_LOCK(td) && oldprio != prio) 903 turnstile_adjust(td, oldprio); 904 } 905 906 void 907 sched_user_prio(struct thread *td, u_char prio) 908 { 909 910 THREAD_LOCK_ASSERT(td, MA_OWNED); 911 td->td_base_user_pri = prio; 912 if (td->td_lend_user_pri <= prio) 913 return; 914 td->td_user_pri = prio; 915 } 916 917 void 918 sched_lend_user_prio(struct thread *td, u_char prio) 919 { 920 921 THREAD_LOCK_ASSERT(td, MA_OWNED); 922 td->td_lend_user_pri = prio; 923 td->td_user_pri = min(prio, td->td_base_user_pri); 924 if (td->td_priority > td->td_user_pri) 925 sched_prio(td, td->td_user_pri); 926 else if (td->td_priority != td->td_user_pri) 927 td->td_flags |= TDF_NEEDRESCHED; 928 } 929 930 void 931 sched_sleep(struct thread *td, int pri) 932 { 933 934 THREAD_LOCK_ASSERT(td, MA_OWNED); 935 td->td_slptick = ticks; 936 td_get_sched(td)->ts_slptime = 0; 937 if (pri != 0 && PRI_BASE(td->td_pri_class) == PRI_TIMESHARE) 938 sched_prio(td, pri); 939 if (TD_IS_SUSPENDED(td) || pri >= PSOCK) 940 td->td_flags |= TDF_CANSWAP; 941 } 942 943 void 944 sched_switch(struct thread *td, struct thread *newtd, int flags) 945 { 946 struct mtx *tmtx; 947 struct td_sched *ts; 948 struct proc *p; 949 int preempted; 950 951 tmtx = NULL; 952 ts = td_get_sched(td); 953 p = td->td_proc; 954 955 THREAD_LOCK_ASSERT(td, MA_OWNED); 956 957 /* 958 * Switch to the sched lock to fix things up and pick 959 * a new thread. 960 * Block the td_lock in order to avoid breaking the critical path. 961 */ 962 if (td->td_lock != &sched_lock) { 963 mtx_lock_spin(&sched_lock); 964 tmtx = thread_lock_block(td); 965 } 966 967 if ((td->td_flags & TDF_NOLOAD) == 0) 968 sched_load_rem(); 969 970 td->td_lastcpu = td->td_oncpu; 971 preempted = (td->td_flags & TDF_SLICEEND) == 0 && 972 (flags & SW_PREEMPT) != 0; 973 td->td_flags &= ~(TDF_NEEDRESCHED | TDF_SLICEEND); 974 td->td_owepreempt = 0; 975 td->td_oncpu = NOCPU; 976 977 /* 978 * At the last moment, if this thread is still marked RUNNING, 979 * then put it back on the run queue as it has not been suspended 980 * or stopped or any thing else similar. We never put the idle 981 * threads on the run queue, however. 982 */ 983 if (td->td_flags & TDF_IDLETD) { 984 TD_SET_CAN_RUN(td); 985 #ifdef SMP 986 CPU_CLR(PCPU_GET(cpuid), &idle_cpus_mask); 987 #endif 988 } else { 989 if (TD_IS_RUNNING(td)) { 990 /* Put us back on the run queue. */ 991 sched_add(td, preempted ? 992 SRQ_OURSELF|SRQ_YIELDING|SRQ_PREEMPTED : 993 SRQ_OURSELF|SRQ_YIELDING); 994 } 995 } 996 if (newtd) { 997 /* 998 * The thread we are about to run needs to be counted 999 * as if it had been added to the run queue and selected. 1000 * It came from: 1001 * * A preemption 1002 * * An upcall 1003 * * A followon 1004 */ 1005 KASSERT((newtd->td_inhibitors == 0), 1006 ("trying to run inhibited thread")); 1007 newtd->td_flags |= TDF_DIDRUN; 1008 TD_SET_RUNNING(newtd); 1009 if ((newtd->td_flags & TDF_NOLOAD) == 0) 1010 sched_load_add(); 1011 } else { 1012 newtd = choosethread(); 1013 MPASS(newtd->td_lock == &sched_lock); 1014 } 1015 1016 if (td != newtd) { 1017 #ifdef HWPMC_HOOKS 1018 if (PMC_PROC_IS_USING_PMCS(td->td_proc)) 1019 PMC_SWITCH_CONTEXT(td, PMC_FN_CSW_OUT); 1020 #endif 1021 1022 SDT_PROBE2(sched, , , off__cpu, newtd, newtd->td_proc); 1023 1024 /* I feel sleepy */ 1025 lock_profile_release_lock(&sched_lock.lock_object); 1026 #ifdef KDTRACE_HOOKS 1027 /* 1028 * If DTrace has set the active vtime enum to anything 1029 * other than INACTIVE (0), then it should have set the 1030 * function to call. 1031 */ 1032 if (dtrace_vtime_active) 1033 (*dtrace_vtime_switch_func)(newtd); 1034 #endif 1035 1036 cpu_switch(td, newtd, tmtx != NULL ? tmtx : td->td_lock); 1037 lock_profile_obtain_lock_success(&sched_lock.lock_object, 1038 0, 0, __FILE__, __LINE__); 1039 /* 1040 * Where am I? What year is it? 1041 * We are in the same thread that went to sleep above, 1042 * but any amount of time may have passed. All our context 1043 * will still be available as will local variables. 1044 * PCPU values however may have changed as we may have 1045 * changed CPU so don't trust cached values of them. 1046 * New threads will go to fork_exit() instead of here 1047 * so if you change things here you may need to change 1048 * things there too. 1049 * 1050 * If the thread above was exiting it will never wake 1051 * up again here, so either it has saved everything it 1052 * needed to, or the thread_wait() or wait() will 1053 * need to reap it. 1054 */ 1055 1056 SDT_PROBE0(sched, , , on__cpu); 1057 #ifdef HWPMC_HOOKS 1058 if (PMC_PROC_IS_USING_PMCS(td->td_proc)) 1059 PMC_SWITCH_CONTEXT(td, PMC_FN_CSW_IN); 1060 #endif 1061 } else 1062 SDT_PROBE0(sched, , , remain__cpu); 1063 1064 #ifdef SMP 1065 if (td->td_flags & TDF_IDLETD) 1066 CPU_SET(PCPU_GET(cpuid), &idle_cpus_mask); 1067 #endif 1068 sched_lock.mtx_lock = (uintptr_t)td; 1069 td->td_oncpu = PCPU_GET(cpuid); 1070 MPASS(td->td_lock == &sched_lock); 1071 } 1072 1073 void 1074 sched_wakeup(struct thread *td) 1075 { 1076 struct td_sched *ts; 1077 1078 THREAD_LOCK_ASSERT(td, MA_OWNED); 1079 ts = td_get_sched(td); 1080 td->td_flags &= ~TDF_CANSWAP; 1081 if (ts->ts_slptime > 1) { 1082 updatepri(td); 1083 resetpriority(td); 1084 } 1085 td->td_slptick = 0; 1086 ts->ts_slptime = 0; 1087 ts->ts_slice = sched_slice; 1088 sched_add(td, SRQ_BORING); 1089 } 1090 1091 #ifdef SMP 1092 static int 1093 forward_wakeup(int cpunum) 1094 { 1095 struct pcpu *pc; 1096 cpuset_t dontuse, map, map2; 1097 u_int id, me; 1098 int iscpuset; 1099 1100 mtx_assert(&sched_lock, MA_OWNED); 1101 1102 CTR0(KTR_RUNQ, "forward_wakeup()"); 1103 1104 if ((!forward_wakeup_enabled) || 1105 (forward_wakeup_use_mask == 0 && forward_wakeup_use_loop == 0)) 1106 return (0); 1107 if (!smp_started || panicstr) 1108 return (0); 1109 1110 forward_wakeups_requested++; 1111 1112 /* 1113 * Check the idle mask we received against what we calculated 1114 * before in the old version. 1115 */ 1116 me = PCPU_GET(cpuid); 1117 1118 /* Don't bother if we should be doing it ourself. */ 1119 if (CPU_ISSET(me, &idle_cpus_mask) && 1120 (cpunum == NOCPU || me == cpunum)) 1121 return (0); 1122 1123 CPU_SETOF(me, &dontuse); 1124 CPU_OR(&dontuse, &stopped_cpus); 1125 CPU_OR(&dontuse, &hlt_cpus_mask); 1126 CPU_ZERO(&map2); 1127 if (forward_wakeup_use_loop) { 1128 STAILQ_FOREACH(pc, &cpuhead, pc_allcpu) { 1129 id = pc->pc_cpuid; 1130 if (!CPU_ISSET(id, &dontuse) && 1131 pc->pc_curthread == pc->pc_idlethread) { 1132 CPU_SET(id, &map2); 1133 } 1134 } 1135 } 1136 1137 if (forward_wakeup_use_mask) { 1138 map = idle_cpus_mask; 1139 CPU_NAND(&map, &dontuse); 1140 1141 /* If they are both on, compare and use loop if different. */ 1142 if (forward_wakeup_use_loop) { 1143 if (CPU_CMP(&map, &map2)) { 1144 printf("map != map2, loop method preferred\n"); 1145 map = map2; 1146 } 1147 } 1148 } else { 1149 map = map2; 1150 } 1151 1152 /* If we only allow a specific CPU, then mask off all the others. */ 1153 if (cpunum != NOCPU) { 1154 KASSERT((cpunum <= mp_maxcpus),("forward_wakeup: bad cpunum.")); 1155 iscpuset = CPU_ISSET(cpunum, &map); 1156 if (iscpuset == 0) 1157 CPU_ZERO(&map); 1158 else 1159 CPU_SETOF(cpunum, &map); 1160 } 1161 if (!CPU_EMPTY(&map)) { 1162 forward_wakeups_delivered++; 1163 STAILQ_FOREACH(pc, &cpuhead, pc_allcpu) { 1164 id = pc->pc_cpuid; 1165 if (!CPU_ISSET(id, &map)) 1166 continue; 1167 if (cpu_idle_wakeup(pc->pc_cpuid)) 1168 CPU_CLR(id, &map); 1169 } 1170 if (!CPU_EMPTY(&map)) 1171 ipi_selected(map, IPI_AST); 1172 return (1); 1173 } 1174 if (cpunum == NOCPU) 1175 printf("forward_wakeup: Idle processor not found\n"); 1176 return (0); 1177 } 1178 1179 static void 1180 kick_other_cpu(int pri, int cpuid) 1181 { 1182 struct pcpu *pcpu; 1183 int cpri; 1184 1185 pcpu = pcpu_find(cpuid); 1186 if (CPU_ISSET(cpuid, &idle_cpus_mask)) { 1187 forward_wakeups_delivered++; 1188 if (!cpu_idle_wakeup(cpuid)) 1189 ipi_cpu(cpuid, IPI_AST); 1190 return; 1191 } 1192 1193 cpri = pcpu->pc_curthread->td_priority; 1194 if (pri >= cpri) 1195 return; 1196 1197 #if defined(IPI_PREEMPTION) && defined(PREEMPTION) 1198 #if !defined(FULL_PREEMPTION) 1199 if (pri <= PRI_MAX_ITHD) 1200 #endif /* ! FULL_PREEMPTION */ 1201 { 1202 ipi_cpu(cpuid, IPI_PREEMPT); 1203 return; 1204 } 1205 #endif /* defined(IPI_PREEMPTION) && defined(PREEMPTION) */ 1206 1207 pcpu->pc_curthread->td_flags |= TDF_NEEDRESCHED; 1208 ipi_cpu(cpuid, IPI_AST); 1209 return; 1210 } 1211 #endif /* SMP */ 1212 1213 #ifdef SMP 1214 static int 1215 sched_pickcpu(struct thread *td) 1216 { 1217 int best, cpu; 1218 1219 mtx_assert(&sched_lock, MA_OWNED); 1220 1221 if (td->td_lastcpu != NOCPU && THREAD_CAN_SCHED(td, td->td_lastcpu)) 1222 best = td->td_lastcpu; 1223 else 1224 best = NOCPU; 1225 CPU_FOREACH(cpu) { 1226 if (!THREAD_CAN_SCHED(td, cpu)) 1227 continue; 1228 1229 if (best == NOCPU) 1230 best = cpu; 1231 else if (runq_length[cpu] < runq_length[best]) 1232 best = cpu; 1233 } 1234 KASSERT(best != NOCPU, ("no valid CPUs")); 1235 1236 return (best); 1237 } 1238 #endif 1239 1240 void 1241 sched_add(struct thread *td, int flags) 1242 #ifdef SMP 1243 { 1244 cpuset_t tidlemsk; 1245 struct td_sched *ts; 1246 u_int cpu, cpuid; 1247 int forwarded = 0; 1248 int single_cpu = 0; 1249 1250 ts = td_get_sched(td); 1251 THREAD_LOCK_ASSERT(td, MA_OWNED); 1252 KASSERT((td->td_inhibitors == 0), 1253 ("sched_add: trying to run inhibited thread")); 1254 KASSERT((TD_CAN_RUN(td) || TD_IS_RUNNING(td)), 1255 ("sched_add: bad thread state")); 1256 KASSERT(td->td_flags & TDF_INMEM, 1257 ("sched_add: thread swapped out")); 1258 1259 KTR_STATE2(KTR_SCHED, "thread", sched_tdname(td), "runq add", 1260 "prio:%d", td->td_priority, KTR_ATTR_LINKED, 1261 sched_tdname(curthread)); 1262 KTR_POINT1(KTR_SCHED, "thread", sched_tdname(curthread), "wokeup", 1263 KTR_ATTR_LINKED, sched_tdname(td)); 1264 SDT_PROBE4(sched, , , enqueue, td, td->td_proc, NULL, 1265 flags & SRQ_PREEMPTED); 1266 1267 1268 /* 1269 * Now that the thread is moving to the run-queue, set the lock 1270 * to the scheduler's lock. 1271 */ 1272 if (td->td_lock != &sched_lock) { 1273 mtx_lock_spin(&sched_lock); 1274 thread_lock_set(td, &sched_lock); 1275 } 1276 TD_SET_RUNQ(td); 1277 1278 /* 1279 * If SMP is started and the thread is pinned or otherwise limited to 1280 * a specific set of CPUs, queue the thread to a per-CPU run queue. 1281 * Otherwise, queue the thread to the global run queue. 1282 * 1283 * If SMP has not yet been started we must use the global run queue 1284 * as per-CPU state may not be initialized yet and we may crash if we 1285 * try to access the per-CPU run queues. 1286 */ 1287 if (smp_started && (td->td_pinned != 0 || td->td_flags & TDF_BOUND || 1288 ts->ts_flags & TSF_AFFINITY)) { 1289 if (td->td_pinned != 0) 1290 cpu = td->td_lastcpu; 1291 else if (td->td_flags & TDF_BOUND) { 1292 /* Find CPU from bound runq. */ 1293 KASSERT(SKE_RUNQ_PCPU(ts), 1294 ("sched_add: bound td_sched not on cpu runq")); 1295 cpu = ts->ts_runq - &runq_pcpu[0]; 1296 } else 1297 /* Find a valid CPU for our cpuset */ 1298 cpu = sched_pickcpu(td); 1299 ts->ts_runq = &runq_pcpu[cpu]; 1300 single_cpu = 1; 1301 CTR3(KTR_RUNQ, 1302 "sched_add: Put td_sched:%p(td:%p) on cpu%d runq", ts, td, 1303 cpu); 1304 } else { 1305 CTR2(KTR_RUNQ, 1306 "sched_add: adding td_sched:%p (td:%p) to gbl runq", ts, 1307 td); 1308 cpu = NOCPU; 1309 ts->ts_runq = &runq; 1310 } 1311 1312 if ((td->td_flags & TDF_NOLOAD) == 0) 1313 sched_load_add(); 1314 runq_add(ts->ts_runq, td, flags); 1315 if (cpu != NOCPU) 1316 runq_length[cpu]++; 1317 1318 cpuid = PCPU_GET(cpuid); 1319 if (single_cpu && cpu != cpuid) { 1320 kick_other_cpu(td->td_priority, cpu); 1321 } else { 1322 if (!single_cpu) { 1323 tidlemsk = idle_cpus_mask; 1324 CPU_NAND(&tidlemsk, &hlt_cpus_mask); 1325 CPU_CLR(cpuid, &tidlemsk); 1326 1327 if (!CPU_ISSET(cpuid, &idle_cpus_mask) && 1328 ((flags & SRQ_INTR) == 0) && 1329 !CPU_EMPTY(&tidlemsk)) 1330 forwarded = forward_wakeup(cpu); 1331 } 1332 1333 if (!forwarded) { 1334 if (!maybe_preempt(td)) 1335 maybe_resched(td); 1336 } 1337 } 1338 } 1339 #else /* SMP */ 1340 { 1341 struct td_sched *ts; 1342 1343 ts = td_get_sched(td); 1344 THREAD_LOCK_ASSERT(td, MA_OWNED); 1345 KASSERT((td->td_inhibitors == 0), 1346 ("sched_add: trying to run inhibited thread")); 1347 KASSERT((TD_CAN_RUN(td) || TD_IS_RUNNING(td)), 1348 ("sched_add: bad thread state")); 1349 KASSERT(td->td_flags & TDF_INMEM, 1350 ("sched_add: thread swapped out")); 1351 KTR_STATE2(KTR_SCHED, "thread", sched_tdname(td), "runq add", 1352 "prio:%d", td->td_priority, KTR_ATTR_LINKED, 1353 sched_tdname(curthread)); 1354 KTR_POINT1(KTR_SCHED, "thread", sched_tdname(curthread), "wokeup", 1355 KTR_ATTR_LINKED, sched_tdname(td)); 1356 SDT_PROBE4(sched, , , enqueue, td, td->td_proc, NULL, 1357 flags & SRQ_PREEMPTED); 1358 1359 /* 1360 * Now that the thread is moving to the run-queue, set the lock 1361 * to the scheduler's lock. 1362 */ 1363 if (td->td_lock != &sched_lock) { 1364 mtx_lock_spin(&sched_lock); 1365 thread_lock_set(td, &sched_lock); 1366 } 1367 TD_SET_RUNQ(td); 1368 CTR2(KTR_RUNQ, "sched_add: adding td_sched:%p (td:%p) to runq", ts, td); 1369 ts->ts_runq = &runq; 1370 1371 if ((td->td_flags & TDF_NOLOAD) == 0) 1372 sched_load_add(); 1373 runq_add(ts->ts_runq, td, flags); 1374 if (!maybe_preempt(td)) 1375 maybe_resched(td); 1376 } 1377 #endif /* SMP */ 1378 1379 void 1380 sched_rem(struct thread *td) 1381 { 1382 struct td_sched *ts; 1383 1384 ts = td_get_sched(td); 1385 KASSERT(td->td_flags & TDF_INMEM, 1386 ("sched_rem: thread swapped out")); 1387 KASSERT(TD_ON_RUNQ(td), 1388 ("sched_rem: thread not on run queue")); 1389 mtx_assert(&sched_lock, MA_OWNED); 1390 KTR_STATE2(KTR_SCHED, "thread", sched_tdname(td), "runq rem", 1391 "prio:%d", td->td_priority, KTR_ATTR_LINKED, 1392 sched_tdname(curthread)); 1393 SDT_PROBE3(sched, , , dequeue, td, td->td_proc, NULL); 1394 1395 if ((td->td_flags & TDF_NOLOAD) == 0) 1396 sched_load_rem(); 1397 #ifdef SMP 1398 if (ts->ts_runq != &runq) 1399 runq_length[ts->ts_runq - runq_pcpu]--; 1400 #endif 1401 runq_remove(ts->ts_runq, td); 1402 TD_SET_CAN_RUN(td); 1403 } 1404 1405 /* 1406 * Select threads to run. Note that running threads still consume a 1407 * slot. 1408 */ 1409 struct thread * 1410 sched_choose(void) 1411 { 1412 struct thread *td; 1413 struct runq *rq; 1414 1415 mtx_assert(&sched_lock, MA_OWNED); 1416 #ifdef SMP 1417 struct thread *tdcpu; 1418 1419 rq = &runq; 1420 td = runq_choose_fuzz(&runq, runq_fuzz); 1421 tdcpu = runq_choose(&runq_pcpu[PCPU_GET(cpuid)]); 1422 1423 if (td == NULL || 1424 (tdcpu != NULL && 1425 tdcpu->td_priority < td->td_priority)) { 1426 CTR2(KTR_RUNQ, "choosing td %p from pcpu runq %d", tdcpu, 1427 PCPU_GET(cpuid)); 1428 td = tdcpu; 1429 rq = &runq_pcpu[PCPU_GET(cpuid)]; 1430 } else { 1431 CTR1(KTR_RUNQ, "choosing td_sched %p from main runq", td); 1432 } 1433 1434 #else 1435 rq = &runq; 1436 td = runq_choose(&runq); 1437 #endif 1438 1439 if (td) { 1440 #ifdef SMP 1441 if (td == tdcpu) 1442 runq_length[PCPU_GET(cpuid)]--; 1443 #endif 1444 runq_remove(rq, td); 1445 td->td_flags |= TDF_DIDRUN; 1446 1447 KASSERT(td->td_flags & TDF_INMEM, 1448 ("sched_choose: thread swapped out")); 1449 return (td); 1450 } 1451 return (PCPU_GET(idlethread)); 1452 } 1453 1454 void 1455 sched_preempt(struct thread *td) 1456 { 1457 1458 SDT_PROBE2(sched, , , surrender, td, td->td_proc); 1459 thread_lock(td); 1460 if (td->td_critnest > 1) 1461 td->td_owepreempt = 1; 1462 else 1463 mi_switch(SW_INVOL | SW_PREEMPT | SWT_PREEMPT, NULL); 1464 thread_unlock(td); 1465 } 1466 1467 void 1468 sched_userret(struct thread *td) 1469 { 1470 /* 1471 * XXX we cheat slightly on the locking here to avoid locking in 1472 * the usual case. Setting td_priority here is essentially an 1473 * incomplete workaround for not setting it properly elsewhere. 1474 * Now that some interrupt handlers are threads, not setting it 1475 * properly elsewhere can clobber it in the window between setting 1476 * it here and returning to user mode, so don't waste time setting 1477 * it perfectly here. 1478 */ 1479 KASSERT((td->td_flags & TDF_BORROWING) == 0, 1480 ("thread with borrowed priority returning to userland")); 1481 if (td->td_priority != td->td_user_pri) { 1482 thread_lock(td); 1483 td->td_priority = td->td_user_pri; 1484 td->td_base_pri = td->td_user_pri; 1485 thread_unlock(td); 1486 } 1487 } 1488 1489 void 1490 sched_bind(struct thread *td, int cpu) 1491 { 1492 struct td_sched *ts; 1493 1494 THREAD_LOCK_ASSERT(td, MA_OWNED|MA_NOTRECURSED); 1495 KASSERT(td == curthread, ("sched_bind: can only bind curthread")); 1496 1497 ts = td_get_sched(td); 1498 1499 td->td_flags |= TDF_BOUND; 1500 #ifdef SMP 1501 ts->ts_runq = &runq_pcpu[cpu]; 1502 if (PCPU_GET(cpuid) == cpu) 1503 return; 1504 1505 mi_switch(SW_VOL, NULL); 1506 #endif 1507 } 1508 1509 void 1510 sched_unbind(struct thread* td) 1511 { 1512 THREAD_LOCK_ASSERT(td, MA_OWNED); 1513 KASSERT(td == curthread, ("sched_unbind: can only bind curthread")); 1514 td->td_flags &= ~TDF_BOUND; 1515 } 1516 1517 int 1518 sched_is_bound(struct thread *td) 1519 { 1520 THREAD_LOCK_ASSERT(td, MA_OWNED); 1521 return (td->td_flags & TDF_BOUND); 1522 } 1523 1524 void 1525 sched_relinquish(struct thread *td) 1526 { 1527 thread_lock(td); 1528 mi_switch(SW_VOL | SWT_RELINQUISH, NULL); 1529 thread_unlock(td); 1530 } 1531 1532 int 1533 sched_load(void) 1534 { 1535 return (sched_tdcnt); 1536 } 1537 1538 int 1539 sched_sizeof_proc(void) 1540 { 1541 return (sizeof(struct proc)); 1542 } 1543 1544 int 1545 sched_sizeof_thread(void) 1546 { 1547 return (sizeof(struct thread) + sizeof(struct td_sched)); 1548 } 1549 1550 fixpt_t 1551 sched_pctcpu(struct thread *td) 1552 { 1553 struct td_sched *ts; 1554 1555 THREAD_LOCK_ASSERT(td, MA_OWNED); 1556 ts = td_get_sched(td); 1557 return (ts->ts_pctcpu); 1558 } 1559 1560 #ifdef RACCT 1561 /* 1562 * Calculates the contribution to the thread cpu usage for the latest 1563 * (unfinished) second. 1564 */ 1565 fixpt_t 1566 sched_pctcpu_delta(struct thread *td) 1567 { 1568 struct td_sched *ts; 1569 fixpt_t delta; 1570 int realstathz; 1571 1572 THREAD_LOCK_ASSERT(td, MA_OWNED); 1573 ts = td_get_sched(td); 1574 delta = 0; 1575 realstathz = stathz ? stathz : hz; 1576 if (ts->ts_cpticks != 0) { 1577 #if (FSHIFT >= CCPU_SHIFT) 1578 delta = (realstathz == 100) 1579 ? ((fixpt_t) ts->ts_cpticks) << 1580 (FSHIFT - CCPU_SHIFT) : 1581 100 * (((fixpt_t) ts->ts_cpticks) 1582 << (FSHIFT - CCPU_SHIFT)) / realstathz; 1583 #else 1584 delta = ((FSCALE - ccpu) * 1585 (ts->ts_cpticks * 1586 FSCALE / realstathz)) >> FSHIFT; 1587 #endif 1588 } 1589 1590 return (delta); 1591 } 1592 #endif 1593 1594 u_int 1595 sched_estcpu(struct thread *td) 1596 { 1597 1598 return (td_get_sched(td)->ts_estcpu); 1599 } 1600 1601 /* 1602 * The actual idle process. 1603 */ 1604 void 1605 sched_idletd(void *dummy) 1606 { 1607 struct pcpuidlestat *stat; 1608 1609 THREAD_NO_SLEEPING(); 1610 stat = DPCPU_PTR(idlestat); 1611 for (;;) { 1612 mtx_assert(&Giant, MA_NOTOWNED); 1613 1614 while (sched_runnable() == 0) { 1615 cpu_idle(stat->idlecalls + stat->oldidlecalls > 64); 1616 stat->idlecalls++; 1617 } 1618 1619 mtx_lock_spin(&sched_lock); 1620 mi_switch(SW_VOL | SWT_IDLE, NULL); 1621 mtx_unlock_spin(&sched_lock); 1622 } 1623 } 1624 1625 /* 1626 * A CPU is entering for the first time or a thread is exiting. 1627 */ 1628 void 1629 sched_throw(struct thread *td) 1630 { 1631 /* 1632 * Correct spinlock nesting. The idle thread context that we are 1633 * borrowing was created so that it would start out with a single 1634 * spin lock (sched_lock) held in fork_trampoline(). Since we've 1635 * explicitly acquired locks in this function, the nesting count 1636 * is now 2 rather than 1. Since we are nested, calling 1637 * spinlock_exit() will simply adjust the counts without allowing 1638 * spin lock using code to interrupt us. 1639 */ 1640 if (td == NULL) { 1641 mtx_lock_spin(&sched_lock); 1642 spinlock_exit(); 1643 PCPU_SET(switchtime, cpu_ticks()); 1644 PCPU_SET(switchticks, ticks); 1645 } else { 1646 lock_profile_release_lock(&sched_lock.lock_object); 1647 MPASS(td->td_lock == &sched_lock); 1648 td->td_lastcpu = td->td_oncpu; 1649 td->td_oncpu = NOCPU; 1650 } 1651 mtx_assert(&sched_lock, MA_OWNED); 1652 KASSERT(curthread->td_md.md_spinlock_count == 1, ("invalid count")); 1653 cpu_throw(td, choosethread()); /* doesn't return */ 1654 } 1655 1656 void 1657 sched_fork_exit(struct thread *td) 1658 { 1659 1660 /* 1661 * Finish setting up thread glue so that it begins execution in a 1662 * non-nested critical section with sched_lock held but not recursed. 1663 */ 1664 td->td_oncpu = PCPU_GET(cpuid); 1665 sched_lock.mtx_lock = (uintptr_t)td; 1666 lock_profile_obtain_lock_success(&sched_lock.lock_object, 1667 0, 0, __FILE__, __LINE__); 1668 THREAD_LOCK_ASSERT(td, MA_OWNED | MA_NOTRECURSED); 1669 } 1670 1671 char * 1672 sched_tdname(struct thread *td) 1673 { 1674 #ifdef KTR 1675 struct td_sched *ts; 1676 1677 ts = td_get_sched(td); 1678 if (ts->ts_name[0] == '\0') 1679 snprintf(ts->ts_name, sizeof(ts->ts_name), 1680 "%s tid %d", td->td_name, td->td_tid); 1681 return (ts->ts_name); 1682 #else 1683 return (td->td_name); 1684 #endif 1685 } 1686 1687 #ifdef KTR 1688 void 1689 sched_clear_tdname(struct thread *td) 1690 { 1691 struct td_sched *ts; 1692 1693 ts = td_get_sched(td); 1694 ts->ts_name[0] = '\0'; 1695 } 1696 #endif 1697 1698 void 1699 sched_affinity(struct thread *td) 1700 { 1701 #ifdef SMP 1702 struct td_sched *ts; 1703 int cpu; 1704 1705 THREAD_LOCK_ASSERT(td, MA_OWNED); 1706 1707 /* 1708 * Set the TSF_AFFINITY flag if there is at least one CPU this 1709 * thread can't run on. 1710 */ 1711 ts = td_get_sched(td); 1712 ts->ts_flags &= ~TSF_AFFINITY; 1713 CPU_FOREACH(cpu) { 1714 if (!THREAD_CAN_SCHED(td, cpu)) { 1715 ts->ts_flags |= TSF_AFFINITY; 1716 break; 1717 } 1718 } 1719 1720 /* 1721 * If this thread can run on all CPUs, nothing else to do. 1722 */ 1723 if (!(ts->ts_flags & TSF_AFFINITY)) 1724 return; 1725 1726 /* Pinned threads and bound threads should be left alone. */ 1727 if (td->td_pinned != 0 || td->td_flags & TDF_BOUND) 1728 return; 1729 1730 switch (td->td_state) { 1731 case TDS_RUNQ: 1732 /* 1733 * If we are on a per-CPU runqueue that is in the set, 1734 * then nothing needs to be done. 1735 */ 1736 if (ts->ts_runq != &runq && 1737 THREAD_CAN_SCHED(td, ts->ts_runq - runq_pcpu)) 1738 return; 1739 1740 /* Put this thread on a valid per-CPU runqueue. */ 1741 sched_rem(td); 1742 sched_add(td, SRQ_BORING); 1743 break; 1744 case TDS_RUNNING: 1745 /* 1746 * See if our current CPU is in the set. If not, force a 1747 * context switch. 1748 */ 1749 if (THREAD_CAN_SCHED(td, td->td_oncpu)) 1750 return; 1751 1752 td->td_flags |= TDF_NEEDRESCHED; 1753 if (td != curthread) 1754 ipi_cpu(cpu, IPI_AST); 1755 break; 1756 default: 1757 break; 1758 } 1759 #endif 1760 } 1761