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 #define kse td_sched 39 40 #include <sys/param.h> 41 #include <sys/systm.h> 42 #include <sys/kernel.h> 43 #include <sys/ktr.h> 44 #include <sys/lock.h> 45 #include <sys/kthread.h> 46 #include <sys/mutex.h> 47 #include <sys/proc.h> 48 #include <sys/resourcevar.h> 49 #include <sys/sched.h> 50 #include <sys/smp.h> 51 #include <sys/sysctl.h> 52 #include <sys/sx.h> 53 #include <machine/smp.h> 54 55 /* 56 * INVERSE_ESTCPU_WEIGHT is only suitable for statclock() frequencies in 57 * the range 100-256 Hz (approximately). 58 */ 59 #define ESTCPULIM(e) \ 60 min((e), INVERSE_ESTCPU_WEIGHT * (NICE_WEIGHT * (PRIO_MAX - PRIO_MIN) - \ 61 RQ_PPQ) + INVERSE_ESTCPU_WEIGHT - 1) 62 #ifdef SMP 63 #define INVERSE_ESTCPU_WEIGHT (8 * smp_cpus) 64 #else 65 #define INVERSE_ESTCPU_WEIGHT 8 /* 1 / (priorities per estcpu level). */ 66 #endif 67 #define NICE_WEIGHT 1 /* Priorities per nice level. */ 68 69 /* 70 * The schedulable entity that can be given a context to run. 71 * A process may have several of these. Probably one per processor 72 * but posibly a few more. In this universe they are grouped 73 * with a KSEG that contains the priority and niceness 74 * for the group. 75 */ 76 struct kse { 77 TAILQ_ENTRY(kse) ke_procq; /* (j/z) Run queue. */ 78 struct thread *ke_thread; /* (*) Active associated thread. */ 79 fixpt_t ke_pctcpu; /* (j) %cpu during p_swtime. */ 80 char ke_rqindex; /* (j) Run queue index. */ 81 enum { 82 KES_THREAD = 0x0, /* slaved to thread state */ 83 KES_ONRUNQ 84 } ke_state; /* (j) KSE status. */ 85 int ke_cpticks; /* (j) Ticks of cpu time. */ 86 struct runq *ke_runq; /* runq the kse is currently on */ 87 }; 88 89 #define ke_proc ke_thread->td_proc 90 #define ke_ksegrp ke_thread->td_ksegrp 91 92 #define td_kse td_sched 93 94 /* flags kept in td_flags */ 95 #define TDF_DIDRUN TDF_SCHED0 /* KSE actually ran. */ 96 #define TDF_EXIT TDF_SCHED1 /* KSE is being killed. */ 97 #define TDF_BOUND TDF_SCHED2 98 99 #define ke_flags ke_thread->td_flags 100 #define KEF_DIDRUN TDF_DIDRUN /* KSE actually ran. */ 101 #define KEF_EXIT TDF_EXIT /* KSE is being killed. */ 102 #define KEF_BOUND TDF_BOUND /* stuck to one CPU */ 103 104 #define SKE_RUNQ_PCPU(ke) \ 105 ((ke)->ke_runq != 0 && (ke)->ke_runq != &runq) 106 107 struct kg_sched { 108 struct thread *skg_last_assigned; /* (j) Last thread assigned to */ 109 /* the system scheduler. */ 110 int skg_avail_opennings; /* (j) Num KSEs requested in group. */ 111 int skg_concurrency; /* (j) Num KSEs requested in group. */ 112 }; 113 #define kg_last_assigned kg_sched->skg_last_assigned 114 #define kg_avail_opennings kg_sched->skg_avail_opennings 115 #define kg_concurrency kg_sched->skg_concurrency 116 117 #define SLOT_RELEASE(kg) \ 118 do { \ 119 kg->kg_avail_opennings++; \ 120 CTR3(KTR_RUNQ, "kg %p(%d) Slot released (->%d)", \ 121 kg, \ 122 kg->kg_concurrency, \ 123 kg->kg_avail_opennings); \ 124 /* KASSERT((kg->kg_avail_opennings <= kg->kg_concurrency), \ 125 ("slots out of whack"));*/ \ 126 } while (0) 127 128 #define SLOT_USE(kg) \ 129 do { \ 130 kg->kg_avail_opennings--; \ 131 CTR3(KTR_RUNQ, "kg %p(%d) Slot used (->%d)", \ 132 kg, \ 133 kg->kg_concurrency, \ 134 kg->kg_avail_opennings); \ 135 /* KASSERT((kg->kg_avail_opennings >= 0), \ 136 ("slots out of whack"));*/ \ 137 } while (0) 138 139 /* 140 * KSE_CAN_MIGRATE macro returns true if the kse can migrate between 141 * cpus. 142 */ 143 #define KSE_CAN_MIGRATE(ke) \ 144 ((ke)->ke_thread->td_pinned == 0 && ((ke)->ke_flags & KEF_BOUND) == 0) 145 146 static struct kse kse0; 147 static struct kg_sched kg_sched0; 148 149 static int sched_tdcnt; /* Total runnable threads in the system. */ 150 static int sched_quantum; /* Roundrobin scheduling quantum in ticks. */ 151 #define SCHED_QUANTUM (hz / 10) /* Default sched quantum */ 152 153 static struct callout roundrobin_callout; 154 155 static void slot_fill(struct ksegrp *kg); 156 static struct kse *sched_choose(void); /* XXX Should be thread * */ 157 158 static void setup_runqs(void); 159 static void roundrobin(void *arg); 160 static void schedcpu(void); 161 static void schedcpu_thread(void); 162 static void sched_setup(void *dummy); 163 static void maybe_resched(struct thread *td); 164 static void updatepri(struct ksegrp *kg); 165 static void resetpriority(struct ksegrp *kg); 166 #ifdef SMP 167 static int forward_wakeup(int cpunum); 168 #endif 169 170 static struct kproc_desc sched_kp = { 171 "schedcpu", 172 schedcpu_thread, 173 NULL 174 }; 175 SYSINIT(schedcpu, SI_SUB_RUN_SCHEDULER, SI_ORDER_FIRST, kproc_start, &sched_kp) 176 SYSINIT(sched_setup, SI_SUB_RUN_QUEUE, SI_ORDER_FIRST, sched_setup, NULL) 177 178 /* 179 * Global run queue. 180 */ 181 static struct runq runq; 182 183 #ifdef SMP 184 /* 185 * Per-CPU run queues 186 */ 187 static struct runq runq_pcpu[MAXCPU]; 188 #endif 189 190 static void 191 setup_runqs(void) 192 { 193 #ifdef SMP 194 int i; 195 196 for (i = 0; i < MAXCPU; ++i) 197 runq_init(&runq_pcpu[i]); 198 #endif 199 200 runq_init(&runq); 201 } 202 203 static int 204 sysctl_kern_quantum(SYSCTL_HANDLER_ARGS) 205 { 206 int error, new_val; 207 208 new_val = sched_quantum * tick; 209 error = sysctl_handle_int(oidp, &new_val, 0, req); 210 if (error != 0 || req->newptr == NULL) 211 return (error); 212 if (new_val < tick) 213 return (EINVAL); 214 sched_quantum = new_val / tick; 215 hogticks = 2 * sched_quantum; 216 return (0); 217 } 218 219 SYSCTL_NODE(_kern, OID_AUTO, sched, CTLFLAG_RD, 0, "Scheduler"); 220 221 SYSCTL_STRING(_kern_sched, OID_AUTO, name, CTLFLAG_RD, "4BSD", 0, 222 "Scheduler name"); 223 224 SYSCTL_PROC(_kern_sched, OID_AUTO, quantum, CTLTYPE_INT | CTLFLAG_RW, 225 0, sizeof sched_quantum, sysctl_kern_quantum, "I", 226 "Roundrobin scheduling quantum in microseconds"); 227 228 #ifdef SMP 229 /* Enable forwarding of wakeups to all other cpus */ 230 SYSCTL_NODE(_kern_sched, OID_AUTO, ipiwakeup, CTLFLAG_RD, NULL, "Kernel SMP"); 231 232 static int forward_wakeup_enabled = 1; 233 SYSCTL_INT(_kern_sched_ipiwakeup, OID_AUTO, enabled, CTLFLAG_RW, 234 &forward_wakeup_enabled, 0, 235 "Forwarding of wakeup to idle CPUs"); 236 237 static int forward_wakeups_requested = 0; 238 SYSCTL_INT(_kern_sched_ipiwakeup, OID_AUTO, requested, CTLFLAG_RD, 239 &forward_wakeups_requested, 0, 240 "Requests for Forwarding of wakeup to idle CPUs"); 241 242 static int forward_wakeups_delivered = 0; 243 SYSCTL_INT(_kern_sched_ipiwakeup, OID_AUTO, delivered, CTLFLAG_RD, 244 &forward_wakeups_delivered, 0, 245 "Completed Forwarding of wakeup to idle CPUs"); 246 247 static int forward_wakeup_use_mask = 1; 248 SYSCTL_INT(_kern_sched_ipiwakeup, OID_AUTO, usemask, CTLFLAG_RW, 249 &forward_wakeup_use_mask, 0, 250 "Use the mask of idle cpus"); 251 252 static int forward_wakeup_use_loop = 0; 253 SYSCTL_INT(_kern_sched_ipiwakeup, OID_AUTO, useloop, CTLFLAG_RW, 254 &forward_wakeup_use_loop, 0, 255 "Use a loop to find idle cpus"); 256 257 static int forward_wakeup_use_single = 0; 258 SYSCTL_INT(_kern_sched_ipiwakeup, OID_AUTO, onecpu, CTLFLAG_RW, 259 &forward_wakeup_use_single, 0, 260 "Only signal one idle cpu"); 261 262 static int forward_wakeup_use_htt = 0; 263 SYSCTL_INT(_kern_sched_ipiwakeup, OID_AUTO, htt2, CTLFLAG_RW, 264 &forward_wakeup_use_htt, 0, 265 "account for htt"); 266 267 #endif 268 static int sched_followon = 0; 269 SYSCTL_INT(_kern_sched, OID_AUTO, followon, CTLFLAG_RW, 270 &sched_followon, 0, 271 "allow threads to share a quantum"); 272 273 static int sched_pfollowons = 0; 274 SYSCTL_INT(_kern_sched, OID_AUTO, pfollowons, CTLFLAG_RD, 275 &sched_pfollowons, 0, 276 "number of followons done to a different ksegrp"); 277 278 static int sched_kgfollowons = 0; 279 SYSCTL_INT(_kern_sched, OID_AUTO, kgfollowons, CTLFLAG_RD, 280 &sched_kgfollowons, 0, 281 "number of followons done in a ksegrp"); 282 283 /* 284 * Arrange to reschedule if necessary, taking the priorities and 285 * schedulers into account. 286 */ 287 static void 288 maybe_resched(struct thread *td) 289 { 290 291 mtx_assert(&sched_lock, MA_OWNED); 292 if (td->td_priority < curthread->td_priority) 293 curthread->td_flags |= TDF_NEEDRESCHED; 294 } 295 296 /* 297 * Force switch among equal priority processes every 100ms. 298 * We don't actually need to force a context switch of the current process. 299 * The act of firing the event triggers a context switch to softclock() and 300 * then switching back out again which is equivalent to a preemption, thus 301 * no further work is needed on the local CPU. 302 */ 303 /* ARGSUSED */ 304 static void 305 roundrobin(void *arg) 306 { 307 308 #ifdef SMP 309 mtx_lock_spin(&sched_lock); 310 forward_roundrobin(); 311 mtx_unlock_spin(&sched_lock); 312 #endif 313 314 callout_reset(&roundrobin_callout, sched_quantum, roundrobin, NULL); 315 } 316 317 /* 318 * Constants for digital decay and forget: 319 * 90% of (kg_estcpu) usage in 5 * loadav time 320 * 95% of (ke_pctcpu) usage in 60 seconds (load insensitive) 321 * Note that, as ps(1) mentions, this can let percentages 322 * total over 100% (I've seen 137.9% for 3 processes). 323 * 324 * Note that schedclock() updates kg_estcpu and p_cpticks asynchronously. 325 * 326 * We wish to decay away 90% of kg_estcpu in (5 * loadavg) seconds. 327 * That is, the system wants to compute a value of decay such 328 * that the following for loop: 329 * for (i = 0; i < (5 * loadavg); i++) 330 * kg_estcpu *= decay; 331 * will compute 332 * kg_estcpu *= 0.1; 333 * for all values of loadavg: 334 * 335 * Mathematically this loop can be expressed by saying: 336 * decay ** (5 * loadavg) ~= .1 337 * 338 * The system computes decay as: 339 * decay = (2 * loadavg) / (2 * loadavg + 1) 340 * 341 * We wish to prove that the system's computation of decay 342 * will always fulfill the equation: 343 * decay ** (5 * loadavg) ~= .1 344 * 345 * If we compute b as: 346 * b = 2 * loadavg 347 * then 348 * decay = b / (b + 1) 349 * 350 * We now need to prove two things: 351 * 1) Given factor ** (5 * loadavg) ~= .1, prove factor == b/(b+1) 352 * 2) Given b/(b+1) ** power ~= .1, prove power == (5 * loadavg) 353 * 354 * Facts: 355 * For x close to zero, exp(x) =~ 1 + x, since 356 * exp(x) = 0! + x**1/1! + x**2/2! + ... . 357 * therefore exp(-1/b) =~ 1 - (1/b) = (b-1)/b. 358 * For x close to zero, ln(1+x) =~ x, since 359 * ln(1+x) = x - x**2/2 + x**3/3 - ... -1 < x < 1 360 * therefore ln(b/(b+1)) = ln(1 - 1/(b+1)) =~ -1/(b+1). 361 * ln(.1) =~ -2.30 362 * 363 * Proof of (1): 364 * Solve (factor)**(power) =~ .1 given power (5*loadav): 365 * solving for factor, 366 * ln(factor) =~ (-2.30/5*loadav), or 367 * factor =~ exp(-1/((5/2.30)*loadav)) =~ exp(-1/(2*loadav)) = 368 * exp(-1/b) =~ (b-1)/b =~ b/(b+1). QED 369 * 370 * Proof of (2): 371 * Solve (factor)**(power) =~ .1 given factor == (b/(b+1)): 372 * solving for power, 373 * power*ln(b/(b+1)) =~ -2.30, or 374 * power =~ 2.3 * (b + 1) = 4.6*loadav + 2.3 =~ 5*loadav. QED 375 * 376 * Actual power values for the implemented algorithm are as follows: 377 * loadav: 1 2 3 4 378 * power: 5.68 10.32 14.94 19.55 379 */ 380 381 /* calculations for digital decay to forget 90% of usage in 5*loadav sec */ 382 #define loadfactor(loadav) (2 * (loadav)) 383 #define decay_cpu(loadfac, cpu) (((loadfac) * (cpu)) / ((loadfac) + FSCALE)) 384 385 /* decay 95% of `ke_pctcpu' in 60 seconds; see CCPU_SHIFT before changing */ 386 static fixpt_t ccpu = 0.95122942450071400909 * FSCALE; /* exp(-1/20) */ 387 SYSCTL_INT(_kern, OID_AUTO, ccpu, CTLFLAG_RD, &ccpu, 0, ""); 388 389 /* 390 * If `ccpu' is not equal to `exp(-1/20)' and you still want to use the 391 * faster/more-accurate formula, you'll have to estimate CCPU_SHIFT below 392 * and possibly adjust FSHIFT in "param.h" so that (FSHIFT >= CCPU_SHIFT). 393 * 394 * To estimate CCPU_SHIFT for exp(-1/20), the following formula was used: 395 * 1 - exp(-1/20) ~= 0.0487 ~= 0.0488 == 1 (fixed pt, *11* bits). 396 * 397 * If you don't want to bother with the faster/more-accurate formula, you 398 * can set CCPU_SHIFT to (FSHIFT + 1) which will use a slower/less-accurate 399 * (more general) method of calculating the %age of CPU used by a process. 400 */ 401 #define CCPU_SHIFT 11 402 403 /* 404 * Recompute process priorities, every hz ticks. 405 * MP-safe, called without the Giant mutex. 406 */ 407 /* ARGSUSED */ 408 static void 409 schedcpu(void) 410 { 411 register fixpt_t loadfac = loadfactor(averunnable.ldavg[0]); 412 struct thread *td; 413 struct proc *p; 414 struct kse *ke; 415 struct ksegrp *kg; 416 int awake, realstathz; 417 418 realstathz = stathz ? stathz : hz; 419 sx_slock(&allproc_lock); 420 FOREACH_PROC_IN_SYSTEM(p) { 421 /* 422 * Prevent state changes and protect run queue. 423 */ 424 mtx_lock_spin(&sched_lock); 425 /* 426 * Increment time in/out of memory. We ignore overflow; with 427 * 16-bit int's (remember them?) overflow takes 45 days. 428 */ 429 p->p_swtime++; 430 FOREACH_KSEGRP_IN_PROC(p, kg) { 431 awake = 0; 432 FOREACH_THREAD_IN_GROUP(kg, td) { 433 ke = td->td_kse; 434 /* 435 * Increment sleep time (if sleeping). We 436 * ignore overflow, as above. 437 */ 438 /* 439 * The kse slptimes are not touched in wakeup 440 * because the thread may not HAVE a KSE. 441 */ 442 if (ke->ke_state == KES_ONRUNQ) { 443 awake = 1; 444 ke->ke_flags &= ~KEF_DIDRUN; 445 } else if ((ke->ke_state == KES_THREAD) && 446 (TD_IS_RUNNING(td))) { 447 awake = 1; 448 /* Do not clear KEF_DIDRUN */ 449 } else if (ke->ke_flags & KEF_DIDRUN) { 450 awake = 1; 451 ke->ke_flags &= ~KEF_DIDRUN; 452 } 453 454 /* 455 * ke_pctcpu is only for ps and ttyinfo(). 456 * Do it per kse, and add them up at the end? 457 * XXXKSE 458 */ 459 ke->ke_pctcpu = (ke->ke_pctcpu * ccpu) >> 460 FSHIFT; 461 /* 462 * If the kse has been idle the entire second, 463 * stop recalculating its priority until 464 * it wakes up. 465 */ 466 if (ke->ke_cpticks == 0) 467 continue; 468 #if (FSHIFT >= CCPU_SHIFT) 469 ke->ke_pctcpu += (realstathz == 100) 470 ? ((fixpt_t) ke->ke_cpticks) << 471 (FSHIFT - CCPU_SHIFT) : 472 100 * (((fixpt_t) ke->ke_cpticks) 473 << (FSHIFT - CCPU_SHIFT)) / realstathz; 474 #else 475 ke->ke_pctcpu += ((FSCALE - ccpu) * 476 (ke->ke_cpticks * 477 FSCALE / realstathz)) >> FSHIFT; 478 #endif 479 ke->ke_cpticks = 0; 480 } /* end of kse loop */ 481 /* 482 * If there are ANY running threads in this KSEGRP, 483 * then don't count it as sleeping. 484 */ 485 if (awake) { 486 if (kg->kg_slptime > 1) { 487 /* 488 * In an ideal world, this should not 489 * happen, because whoever woke us 490 * up from the long sleep should have 491 * unwound the slptime and reset our 492 * priority before we run at the stale 493 * priority. Should KASSERT at some 494 * point when all the cases are fixed. 495 */ 496 updatepri(kg); 497 } 498 kg->kg_slptime = 0; 499 } else 500 kg->kg_slptime++; 501 if (kg->kg_slptime > 1) 502 continue; 503 kg->kg_estcpu = decay_cpu(loadfac, kg->kg_estcpu); 504 resetpriority(kg); 505 FOREACH_THREAD_IN_GROUP(kg, td) { 506 if (td->td_priority >= PUSER) { 507 sched_prio(td, kg->kg_user_pri); 508 } 509 } 510 } /* end of ksegrp loop */ 511 mtx_unlock_spin(&sched_lock); 512 } /* end of process loop */ 513 sx_sunlock(&allproc_lock); 514 } 515 516 /* 517 * Main loop for a kthread that executes schedcpu once a second. 518 */ 519 static void 520 schedcpu_thread(void) 521 { 522 int nowake; 523 524 for (;;) { 525 schedcpu(); 526 tsleep(&nowake, curthread->td_priority, "-", hz); 527 } 528 } 529 530 /* 531 * Recalculate the priority of a process after it has slept for a while. 532 * For all load averages >= 1 and max kg_estcpu of 255, sleeping for at 533 * least six times the loadfactor will decay kg_estcpu to zero. 534 */ 535 static void 536 updatepri(struct ksegrp *kg) 537 { 538 register fixpt_t loadfac; 539 register unsigned int newcpu; 540 541 loadfac = loadfactor(averunnable.ldavg[0]); 542 if (kg->kg_slptime > 5 * loadfac) 543 kg->kg_estcpu = 0; 544 else { 545 newcpu = kg->kg_estcpu; 546 kg->kg_slptime--; /* was incremented in schedcpu() */ 547 while (newcpu && --kg->kg_slptime) 548 newcpu = decay_cpu(loadfac, newcpu); 549 kg->kg_estcpu = newcpu; 550 } 551 resetpriority(kg); 552 } 553 554 /* 555 * Compute the priority of a process when running in user mode. 556 * Arrange to reschedule if the resulting priority is better 557 * than that of the current process. 558 */ 559 static void 560 resetpriority(struct ksegrp *kg) 561 { 562 register unsigned int newpriority; 563 struct thread *td; 564 565 if (kg->kg_pri_class == PRI_TIMESHARE) { 566 newpriority = PUSER + kg->kg_estcpu / INVERSE_ESTCPU_WEIGHT + 567 NICE_WEIGHT * (kg->kg_proc->p_nice - PRIO_MIN); 568 newpriority = min(max(newpriority, PRI_MIN_TIMESHARE), 569 PRI_MAX_TIMESHARE); 570 kg->kg_user_pri = newpriority; 571 } 572 FOREACH_THREAD_IN_GROUP(kg, td) { 573 maybe_resched(td); /* XXXKSE silly */ 574 } 575 } 576 577 /* ARGSUSED */ 578 static void 579 sched_setup(void *dummy) 580 { 581 setup_runqs(); 582 583 if (sched_quantum == 0) 584 sched_quantum = SCHED_QUANTUM; 585 hogticks = 2 * sched_quantum; 586 587 callout_init(&roundrobin_callout, CALLOUT_MPSAFE); 588 589 /* Kick off timeout driven events by calling first time. */ 590 roundrobin(NULL); 591 592 /* Account for thread0. */ 593 sched_tdcnt++; 594 } 595 596 /* External interfaces start here */ 597 /* 598 * Very early in the boot some setup of scheduler-specific 599 * parts of proc0 and of soem scheduler resources needs to be done. 600 * Called from: 601 * proc0_init() 602 */ 603 void 604 schedinit(void) 605 { 606 /* 607 * Set up the scheduler specific parts of proc0. 608 */ 609 proc0.p_sched = NULL; /* XXX */ 610 ksegrp0.kg_sched = &kg_sched0; 611 thread0.td_sched = &kse0; 612 kse0.ke_thread = &thread0; 613 kse0.ke_state = KES_THREAD; 614 kg_sched0.skg_concurrency = 1; 615 kg_sched0.skg_avail_opennings = 0; /* we are already running */ 616 } 617 618 int 619 sched_runnable(void) 620 { 621 #ifdef SMP 622 return runq_check(&runq) + runq_check(&runq_pcpu[PCPU_GET(cpuid)]); 623 #else 624 return runq_check(&runq); 625 #endif 626 } 627 628 int 629 sched_rr_interval(void) 630 { 631 if (sched_quantum == 0) 632 sched_quantum = SCHED_QUANTUM; 633 return (sched_quantum); 634 } 635 636 /* 637 * We adjust the priority of the current process. The priority of 638 * a process gets worse as it accumulates CPU time. The cpu usage 639 * estimator (kg_estcpu) is increased here. resetpriority() will 640 * compute a different priority each time kg_estcpu increases by 641 * INVERSE_ESTCPU_WEIGHT 642 * (until MAXPRI is reached). The cpu usage estimator ramps up 643 * quite quickly when the process is running (linearly), and decays 644 * away exponentially, at a rate which is proportionally slower when 645 * the system is busy. The basic principle is that the system will 646 * 90% forget that the process used a lot of CPU time in 5 * loadav 647 * seconds. This causes the system to favor processes which haven't 648 * run much recently, and to round-robin among other processes. 649 */ 650 void 651 sched_clock(struct thread *td) 652 { 653 struct ksegrp *kg; 654 struct kse *ke; 655 656 mtx_assert(&sched_lock, MA_OWNED); 657 kg = td->td_ksegrp; 658 ke = td->td_kse; 659 660 ke->ke_cpticks++; 661 kg->kg_estcpu = ESTCPULIM(kg->kg_estcpu + 1); 662 if ((kg->kg_estcpu % INVERSE_ESTCPU_WEIGHT) == 0) { 663 resetpriority(kg); 664 if (td->td_priority >= PUSER) 665 td->td_priority = kg->kg_user_pri; 666 } 667 } 668 669 /* 670 * charge childs scheduling cpu usage to parent. 671 * 672 * XXXKSE assume only one thread & kse & ksegrp keep estcpu in each ksegrp. 673 * Charge it to the ksegrp that did the wait since process estcpu is sum of 674 * all ksegrps, this is strictly as expected. Assume that the child process 675 * aggregated all the estcpu into the 'built-in' ksegrp. 676 */ 677 void 678 sched_exit(struct proc *p, struct thread *td) 679 { 680 sched_exit_ksegrp(FIRST_KSEGRP_IN_PROC(p), td); 681 sched_exit_thread(FIRST_THREAD_IN_PROC(p), td); 682 } 683 684 void 685 sched_exit_ksegrp(struct ksegrp *kg, struct thread *childtd) 686 { 687 688 mtx_assert(&sched_lock, MA_OWNED); 689 kg->kg_estcpu = ESTCPULIM(kg->kg_estcpu + childtd->td_ksegrp->kg_estcpu); 690 } 691 692 void 693 sched_exit_thread(struct thread *td, struct thread *child) 694 { 695 if ((child->td_proc->p_flag & P_NOLOAD) == 0) 696 sched_tdcnt--; 697 } 698 699 void 700 sched_fork(struct thread *td, struct thread *childtd) 701 { 702 sched_fork_ksegrp(td, childtd->td_ksegrp); 703 sched_fork_thread(td, childtd); 704 } 705 706 void 707 sched_fork_ksegrp(struct thread *td, struct ksegrp *child) 708 { 709 mtx_assert(&sched_lock, MA_OWNED); 710 child->kg_estcpu = td->td_ksegrp->kg_estcpu; 711 } 712 713 void 714 sched_fork_thread(struct thread *td, struct thread *childtd) 715 { 716 sched_newthread(childtd); 717 } 718 719 void 720 sched_nice(struct proc *p, int nice) 721 { 722 struct ksegrp *kg; 723 724 PROC_LOCK_ASSERT(p, MA_OWNED); 725 mtx_assert(&sched_lock, MA_OWNED); 726 p->p_nice = nice; 727 FOREACH_KSEGRP_IN_PROC(p, kg) { 728 resetpriority(kg); 729 } 730 } 731 732 void 733 sched_class(struct ksegrp *kg, int class) 734 { 735 mtx_assert(&sched_lock, MA_OWNED); 736 kg->kg_pri_class = class; 737 } 738 739 /* 740 * Adjust the priority of a thread. 741 * This may include moving the thread within the KSEGRP, 742 * changing the assignment of a kse to the thread, 743 * and moving a KSE in the system run queue. 744 */ 745 void 746 sched_prio(struct thread *td, u_char prio) 747 { 748 749 mtx_assert(&sched_lock, MA_OWNED); 750 if (TD_ON_RUNQ(td)) { 751 adjustrunqueue(td, prio); 752 } else { 753 td->td_priority = prio; 754 } 755 } 756 757 void 758 sched_sleep(struct thread *td) 759 { 760 761 mtx_assert(&sched_lock, MA_OWNED); 762 td->td_ksegrp->kg_slptime = 0; 763 td->td_base_pri = td->td_priority; 764 } 765 766 static void remrunqueue(struct thread *td); 767 768 void 769 sched_switch(struct thread *td, struct thread *newtd, int flags) 770 { 771 struct kse *ke; 772 struct ksegrp *kg; 773 struct proc *p; 774 775 ke = td->td_kse; 776 p = td->td_proc; 777 778 mtx_assert(&sched_lock, MA_OWNED); 779 780 if ((p->p_flag & P_NOLOAD) == 0) 781 sched_tdcnt--; 782 /* 783 * We are volunteering to switch out so we get to nominate 784 * a successor for the rest of our quantum 785 * First try another thread in our ksegrp, and then look for 786 * other ksegrps in our process. 787 */ 788 if (sched_followon && 789 (p->p_flag & P_HADTHREADS) && 790 (flags & SW_VOL) && 791 newtd == NULL) { 792 /* lets schedule another thread from this process */ 793 kg = td->td_ksegrp; 794 if ((newtd = TAILQ_FIRST(&kg->kg_runq))) { 795 remrunqueue(newtd); 796 sched_kgfollowons++; 797 } else { 798 FOREACH_KSEGRP_IN_PROC(p, kg) { 799 if ((newtd = TAILQ_FIRST(&kg->kg_runq))) { 800 sched_pfollowons++; 801 remrunqueue(newtd); 802 break; 803 } 804 } 805 } 806 } 807 808 if (newtd) 809 newtd->td_flags |= (td->td_flags & TDF_NEEDRESCHED); 810 811 td->td_lastcpu = td->td_oncpu; 812 td->td_flags &= ~TDF_NEEDRESCHED; 813 td->td_pflags &= ~TDP_OWEPREEMPT; 814 td->td_oncpu = NOCPU; 815 /* 816 * At the last moment, if this thread is still marked RUNNING, 817 * then put it back on the run queue as it has not been suspended 818 * or stopped or any thing else similar. We never put the idle 819 * threads on the run queue, however. 820 */ 821 if (td == PCPU_GET(idlethread)) 822 TD_SET_CAN_RUN(td); 823 else { 824 SLOT_RELEASE(td->td_ksegrp); 825 if (TD_IS_RUNNING(td)) { 826 /* Put us back on the run queue (kse and all). */ 827 setrunqueue(td, (flags & SW_PREEMPT) ? 828 SRQ_OURSELF|SRQ_YIELDING|SRQ_PREEMPTED : 829 SRQ_OURSELF|SRQ_YIELDING); 830 } else if (p->p_flag & P_HADTHREADS) { 831 /* 832 * We will not be on the run queue. So we must be 833 * sleeping or similar. As it's available, 834 * someone else can use the KSE if they need it. 835 * It's NOT available if we are about to need it 836 */ 837 if (newtd == NULL || newtd->td_ksegrp != td->td_ksegrp) 838 slot_fill(td->td_ksegrp); 839 } 840 } 841 if (newtd) { 842 /* 843 * The thread we are about to run needs to be counted 844 * as if it had been added to the run queue and selected. 845 * It came from: 846 * * A preemption 847 * * An upcall 848 * * A followon 849 */ 850 KASSERT((newtd->td_inhibitors == 0), 851 ("trying to run inhibitted thread")); 852 SLOT_USE(newtd->td_ksegrp); 853 newtd->td_kse->ke_flags |= KEF_DIDRUN; 854 TD_SET_RUNNING(newtd); 855 if ((newtd->td_proc->p_flag & P_NOLOAD) == 0) 856 sched_tdcnt++; 857 } else { 858 newtd = choosethread(); 859 } 860 861 if (td != newtd) 862 cpu_switch(td, newtd); 863 sched_lock.mtx_lock = (uintptr_t)td; 864 td->td_oncpu = PCPU_GET(cpuid); 865 } 866 867 void 868 sched_wakeup(struct thread *td) 869 { 870 struct ksegrp *kg; 871 872 mtx_assert(&sched_lock, MA_OWNED); 873 kg = td->td_ksegrp; 874 if (kg->kg_slptime > 1) 875 updatepri(kg); 876 kg->kg_slptime = 0; 877 setrunqueue(td, SRQ_BORING); 878 } 879 880 #ifdef SMP 881 /* enable HTT_2 if you have a 2-way HTT cpu.*/ 882 static int 883 forward_wakeup(int cpunum) 884 { 885 cpumask_t map, me, dontuse; 886 cpumask_t map2; 887 struct pcpu *pc; 888 cpumask_t id, map3; 889 890 mtx_assert(&sched_lock, MA_OWNED); 891 892 CTR0(KTR_RUNQ, "forward_wakeup()"); 893 894 if ((!forward_wakeup_enabled) || 895 (forward_wakeup_use_mask == 0 && forward_wakeup_use_loop == 0)) 896 return (0); 897 if (!smp_started || cold || panicstr) 898 return (0); 899 900 forward_wakeups_requested++; 901 902 /* 903 * check the idle mask we received against what we calculated before 904 * in the old version. 905 */ 906 me = PCPU_GET(cpumask); 907 /* 908 * don't bother if we should be doing it ourself.. 909 */ 910 if ((me & idle_cpus_mask) && (cpunum == NOCPU || me == (1 << cpunum))) 911 return (0); 912 913 dontuse = me | stopped_cpus | hlt_cpus_mask; 914 map3 = 0; 915 if (forward_wakeup_use_loop) { 916 SLIST_FOREACH(pc, &cpuhead, pc_allcpu) { 917 id = pc->pc_cpumask; 918 if ( (id & dontuse) == 0 && 919 pc->pc_curthread == pc->pc_idlethread) { 920 map3 |= id; 921 } 922 } 923 } 924 925 if (forward_wakeup_use_mask) { 926 map = 0; 927 map = idle_cpus_mask & ~dontuse; 928 929 /* If they are both on, compare and use loop if different */ 930 if (forward_wakeup_use_loop) { 931 if (map != map3) { 932 printf("map (%02X) != map3 (%02X)\n", 933 map, map3); 934 map = map3; 935 } 936 } 937 } else { 938 map = map3; 939 } 940 /* If we only allow a specific CPU, then mask off all the others */ 941 if (cpunum != NOCPU) { 942 KASSERT((cpunum <= mp_maxcpus),("forward_wakeup: bad cpunum.")); 943 map &= (1 << cpunum); 944 } else { 945 /* Try choose an idle die. */ 946 if (forward_wakeup_use_htt) { 947 map2 = (map & (map >> 1)) & 0x5555; 948 if (map2) { 949 map = map2; 950 } 951 } 952 953 /* set only one bit */ 954 if (forward_wakeup_use_single) { 955 map = map & ((~map) + 1); 956 } 957 } 958 if (map) { 959 forward_wakeups_delivered++; 960 ipi_selected(map, IPI_AST); 961 return (1); 962 } 963 if (cpunum == NOCPU) 964 printf("forward_wakeup: Idle processor not found\n"); 965 return (0); 966 } 967 #endif 968 969 void 970 sched_add(struct thread *td, int flags) 971 { 972 struct kse *ke; 973 #ifdef SMP 974 int forwarded = 0; 975 int cpu; 976 #endif 977 978 ke = td->td_kse; 979 mtx_assert(&sched_lock, MA_OWNED); 980 KASSERT(ke->ke_state != KES_ONRUNQ, 981 ("sched_add: kse %p (%s) already in run queue", ke, 982 ke->ke_proc->p_comm)); 983 KASSERT(ke->ke_proc->p_sflag & PS_INMEM, 984 ("sched_add: process swapped out")); 985 986 #ifdef SMP 987 if (KSE_CAN_MIGRATE(ke)) { 988 CTR2(KTR_RUNQ, 989 "sched_add: adding kse:%p (td:%p) to gbl runq", ke, td); 990 cpu = NOCPU; 991 ke->ke_runq = &runq; 992 } else { 993 if (!SKE_RUNQ_PCPU(ke)) 994 ke->ke_runq = &runq_pcpu[(cpu = PCPU_GET(cpuid))]; 995 else 996 cpu = td->td_lastcpu; 997 CTR3(KTR_RUNQ, 998 "sched_add: Put kse:%p(td:%p) on cpu%d runq", ke, td, cpu); 999 } 1000 #else 1001 CTR2(KTR_RUNQ, "sched_add: adding kse:%p (td:%p) to runq", ke, td); 1002 ke->ke_runq = &runq; 1003 1004 #endif 1005 /* 1006 * If we are yielding (on the way out anyhow) 1007 * or the thread being saved is US, 1008 * then don't try be smart about preemption 1009 * or kicking off another CPU 1010 * as it won't help and may hinder. 1011 * In the YIEDLING case, we are about to run whoever is 1012 * being put in the queue anyhow, and in the 1013 * OURSELF case, we are puting ourself on the run queue 1014 * which also only happens when we are about to yield. 1015 */ 1016 if((flags & SRQ_YIELDING) == 0) { 1017 #ifdef SMP 1018 cpumask_t me = PCPU_GET(cpumask); 1019 int idle = idle_cpus_mask & me; 1020 /* 1021 * Only try to kick off another CPU if 1022 * the thread is unpinned 1023 * or pinned to another cpu, 1024 * and there are other available and idle CPUs. 1025 * if we are idle, or it's an interrupt, 1026 * then skip straight to preemption. 1027 */ 1028 if ( (! idle) && ((flags & SRQ_INTR) == 0) && 1029 (idle_cpus_mask & ~(hlt_cpus_mask | me)) && 1030 ( KSE_CAN_MIGRATE(ke) || 1031 ke->ke_runq != &runq_pcpu[PCPU_GET(cpuid)])) { 1032 forwarded = forward_wakeup(cpu); 1033 } 1034 /* 1035 * If we failed to kick off another cpu, then look to 1036 * see if we should preempt this CPU. Only allow this 1037 * if it is not pinned or IS pinned to this CPU. 1038 * If we are the idle thread, we also try do preempt. 1039 * as it will be quicker and being idle, we won't 1040 * lose in doing so.. 1041 */ 1042 if ((!forwarded) && 1043 (ke->ke_runq == &runq || 1044 ke->ke_runq == &runq_pcpu[PCPU_GET(cpuid)])) 1045 #endif 1046 1047 { 1048 if (maybe_preempt(td)) 1049 return; 1050 } 1051 } 1052 if ((td->td_proc->p_flag & P_NOLOAD) == 0) 1053 sched_tdcnt++; 1054 SLOT_USE(td->td_ksegrp); 1055 runq_add(ke->ke_runq, ke, flags); 1056 ke->ke_state = KES_ONRUNQ; 1057 maybe_resched(td); 1058 } 1059 1060 void 1061 sched_rem(struct thread *td) 1062 { 1063 struct kse *ke; 1064 1065 ke = td->td_kse; 1066 KASSERT(ke->ke_proc->p_sflag & PS_INMEM, 1067 ("sched_rem: process swapped out")); 1068 KASSERT((ke->ke_state == KES_ONRUNQ), 1069 ("sched_rem: KSE not on run queue")); 1070 mtx_assert(&sched_lock, MA_OWNED); 1071 1072 if ((td->td_proc->p_flag & P_NOLOAD) == 0) 1073 sched_tdcnt--; 1074 SLOT_RELEASE(td->td_ksegrp); 1075 runq_remove(ke->ke_runq, ke); 1076 1077 ke->ke_state = KES_THREAD; 1078 } 1079 1080 /* 1081 * Select threads to run. 1082 * Notice that the running threads still consume a slot. 1083 */ 1084 struct kse * 1085 sched_choose(void) 1086 { 1087 struct kse *ke; 1088 struct runq *rq; 1089 1090 #ifdef SMP 1091 struct kse *kecpu; 1092 1093 rq = &runq; 1094 ke = runq_choose(&runq); 1095 kecpu = runq_choose(&runq_pcpu[PCPU_GET(cpuid)]); 1096 1097 if (ke == NULL || 1098 (kecpu != NULL && 1099 kecpu->ke_thread->td_priority < ke->ke_thread->td_priority)) { 1100 CTR2(KTR_RUNQ, "choosing kse %p from pcpu runq %d", kecpu, 1101 PCPU_GET(cpuid)); 1102 ke = kecpu; 1103 rq = &runq_pcpu[PCPU_GET(cpuid)]; 1104 } else { 1105 CTR1(KTR_RUNQ, "choosing kse %p from main runq", ke); 1106 } 1107 1108 #else 1109 rq = &runq; 1110 ke = runq_choose(&runq); 1111 #endif 1112 1113 if (ke != NULL) { 1114 runq_remove(rq, ke); 1115 ke->ke_state = KES_THREAD; 1116 1117 KASSERT(ke->ke_proc->p_sflag & PS_INMEM, 1118 ("sched_choose: process swapped out")); 1119 } 1120 return (ke); 1121 } 1122 1123 void 1124 sched_userret(struct thread *td) 1125 { 1126 struct ksegrp *kg; 1127 /* 1128 * XXX we cheat slightly on the locking here to avoid locking in 1129 * the usual case. Setting td_priority here is essentially an 1130 * incomplete workaround for not setting it properly elsewhere. 1131 * Now that some interrupt handlers are threads, not setting it 1132 * properly elsewhere can clobber it in the window between setting 1133 * it here and returning to user mode, so don't waste time setting 1134 * it perfectly here. 1135 */ 1136 kg = td->td_ksegrp; 1137 if (td->td_priority != kg->kg_user_pri) { 1138 mtx_lock_spin(&sched_lock); 1139 td->td_priority = kg->kg_user_pri; 1140 mtx_unlock_spin(&sched_lock); 1141 } 1142 } 1143 1144 void 1145 sched_bind(struct thread *td, int cpu) 1146 { 1147 struct kse *ke; 1148 1149 mtx_assert(&sched_lock, MA_OWNED); 1150 KASSERT(TD_IS_RUNNING(td), 1151 ("sched_bind: cannot bind non-running thread")); 1152 1153 ke = td->td_kse; 1154 1155 ke->ke_flags |= KEF_BOUND; 1156 #ifdef SMP 1157 ke->ke_runq = &runq_pcpu[cpu]; 1158 if (PCPU_GET(cpuid) == cpu) 1159 return; 1160 1161 ke->ke_state = KES_THREAD; 1162 1163 mi_switch(SW_VOL, NULL); 1164 #endif 1165 } 1166 1167 void 1168 sched_unbind(struct thread* td) 1169 { 1170 mtx_assert(&sched_lock, MA_OWNED); 1171 td->td_kse->ke_flags &= ~KEF_BOUND; 1172 } 1173 1174 int 1175 sched_load(void) 1176 { 1177 return (sched_tdcnt); 1178 } 1179 1180 int 1181 sched_sizeof_ksegrp(void) 1182 { 1183 return (sizeof(struct ksegrp) + sizeof(struct kg_sched)); 1184 } 1185 int 1186 sched_sizeof_proc(void) 1187 { 1188 return (sizeof(struct proc)); 1189 } 1190 int 1191 sched_sizeof_thread(void) 1192 { 1193 return (sizeof(struct thread) + sizeof(struct kse)); 1194 } 1195 1196 fixpt_t 1197 sched_pctcpu(struct thread *td) 1198 { 1199 struct kse *ke; 1200 1201 ke = td->td_kse; 1202 return (ke->ke_pctcpu); 1203 1204 return (0); 1205 } 1206 #define KERN_SWITCH_INCLUDE 1 1207 #include "kern/kern_switch.c" 1208