1 /* $NetBSD: kern_runq.c,v 1.23 2008/12/02 17:57:32 ad Exp $ */ 2 3 /* 4 * Copyright (c) 2007, 2008 Mindaugas Rasiukevicius <rmind at NetBSD org> 5 * All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 17 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 18 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 19 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 20 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 21 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 22 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 23 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 24 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 25 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 26 * SUCH DAMAGE. 27 */ 28 29 #include <sys/cdefs.h> 30 __KERNEL_RCSID(0, "$NetBSD: kern_runq.c,v 1.23 2008/12/02 17:57:32 ad Exp $"); 31 32 #include <sys/param.h> 33 #include <sys/kernel.h> 34 #include <sys/bitops.h> 35 #include <sys/cpu.h> 36 #include <sys/idle.h> 37 #include <sys/intr.h> 38 #include <sys/kmem.h> 39 #include <sys/lwp.h> 40 #include <sys/mutex.h> 41 #include <sys/proc.h> 42 #include <sys/sched.h> 43 #include <sys/syscallargs.h> 44 #include <sys/sysctl.h> 45 #include <sys/systm.h> 46 #include <sys/types.h> 47 #include <sys/evcnt.h> 48 49 /* 50 * Priority related defintions. 51 */ 52 #define PRI_TS_COUNT (NPRI_USER) 53 #define PRI_RT_COUNT (PRI_COUNT - PRI_TS_COUNT) 54 #define PRI_HTS_RANGE (PRI_TS_COUNT / 10) 55 56 #define PRI_HIGHEST_TS (MAXPRI_USER) 57 58 /* 59 * Bits per map. 60 */ 61 #define BITMAP_BITS (32) 62 #define BITMAP_SHIFT (5) 63 #define BITMAP_MSB (0x80000000U) 64 #define BITMAP_MASK (BITMAP_BITS - 1) 65 66 /* 67 * Structures, runqueue. 68 */ 69 70 const int schedppq = 1; 71 72 typedef struct { 73 TAILQ_HEAD(, lwp) q_head; 74 } queue_t; 75 76 typedef struct { 77 /* Lock and bitmap */ 78 uint32_t r_bitmap[PRI_COUNT >> BITMAP_SHIFT]; 79 /* Counters */ 80 u_int r_count; /* Count of the threads */ 81 u_int r_avgcount; /* Average count of threads */ 82 u_int r_mcount; /* Count of migratable threads */ 83 /* Runqueues */ 84 queue_t r_rt_queue[PRI_RT_COUNT]; 85 queue_t r_ts_queue[PRI_TS_COUNT]; 86 /* Event counters */ 87 struct evcnt r_ev_pull; 88 struct evcnt r_ev_push; 89 struct evcnt r_ev_stay; 90 struct evcnt r_ev_localize; 91 } runqueue_t; 92 93 static void * sched_getrq(runqueue_t *, const pri_t); 94 #ifdef MULTIPROCESSOR 95 static lwp_t *sched_catchlwp(struct cpu_info *); 96 static void sched_balance(void *); 97 #endif 98 99 /* 100 * Preemption control. 101 */ 102 int sched_upreempt_pri = PRI_KERNEL; 103 #if defined(__HAVE_PREEMPTION) 104 int sched_kpreempt_pri = PRI_USER_RT; 105 #else 106 int sched_kpreempt_pri = 1000; 107 #endif 108 109 /* 110 * Migration and balancing. 111 */ 112 static u_int cacheht_time; /* Cache hotness time */ 113 static u_int min_catch; /* Minimal LWP count for catching */ 114 static u_int balance_period; /* Balance period */ 115 static struct cpu_info *worker_ci; /* Victim CPU */ 116 #ifdef MULTIPROCESSOR 117 static struct callout balance_ch; /* Callout of balancer */ 118 #endif 119 120 void 121 runq_init(void) 122 { 123 124 /* Balancing */ 125 worker_ci = curcpu(); 126 cacheht_time = mstohz(3); /* ~3 ms */ 127 balance_period = mstohz(300); /* ~300 ms */ 128 129 /* Minimal count of LWPs for catching */ 130 min_catch = 1; 131 132 /* Initialize balancing callout and run it */ 133 #ifdef MULTIPROCESSOR 134 callout_init(&balance_ch, CALLOUT_MPSAFE); 135 callout_setfunc(&balance_ch, sched_balance, NULL); 136 callout_schedule(&balance_ch, balance_period); 137 #endif 138 } 139 140 void 141 sched_cpuattach(struct cpu_info *ci) 142 { 143 runqueue_t *ci_rq; 144 void *rq_ptr; 145 u_int i, size; 146 char *cpuname; 147 148 if (ci->ci_schedstate.spc_lwplock == NULL) { 149 ci->ci_schedstate.spc_lwplock = 150 mutex_obj_alloc(MUTEX_DEFAULT, IPL_SCHED); 151 } 152 if (ci == lwp0.l_cpu) { 153 /* Initialize the scheduler structure of the primary LWP */ 154 lwp0.l_mutex = ci->ci_schedstate.spc_lwplock; 155 } 156 if (ci->ci_schedstate.spc_mutex != NULL) { 157 /* Already initialized. */ 158 return; 159 } 160 161 /* Allocate the run queue */ 162 size = roundup2(sizeof(runqueue_t), coherency_unit) + coherency_unit; 163 rq_ptr = kmem_zalloc(size, KM_SLEEP); 164 if (rq_ptr == NULL) { 165 panic("sched_cpuattach: could not allocate the runqueue"); 166 } 167 ci_rq = (void *)(roundup2((uintptr_t)(rq_ptr), coherency_unit)); 168 169 /* Initialize run queues */ 170 ci->ci_schedstate.spc_mutex = 171 mutex_obj_alloc(MUTEX_DEFAULT, IPL_SCHED); 172 for (i = 0; i < PRI_RT_COUNT; i++) 173 TAILQ_INIT(&ci_rq->r_rt_queue[i].q_head); 174 for (i = 0; i < PRI_TS_COUNT; i++) 175 TAILQ_INIT(&ci_rq->r_ts_queue[i].q_head); 176 177 ci->ci_schedstate.spc_sched_info = ci_rq; 178 179 cpuname = kmem_alloc(8, KM_SLEEP); 180 snprintf(cpuname, 8, "cpu%d", cpu_index(ci)); 181 182 evcnt_attach_dynamic(&ci_rq->r_ev_pull, EVCNT_TYPE_MISC, NULL, 183 cpuname, "runqueue pull"); 184 evcnt_attach_dynamic(&ci_rq->r_ev_push, EVCNT_TYPE_MISC, NULL, 185 cpuname, "runqueue push"); 186 evcnt_attach_dynamic(&ci_rq->r_ev_stay, EVCNT_TYPE_MISC, NULL, 187 cpuname, "runqueue stay"); 188 evcnt_attach_dynamic(&ci_rq->r_ev_localize, EVCNT_TYPE_MISC, NULL, 189 cpuname, "runqueue localize"); 190 } 191 192 /* 193 * Control of the runqueue. 194 */ 195 196 static void * 197 sched_getrq(runqueue_t *ci_rq, const pri_t prio) 198 { 199 200 KASSERT(prio < PRI_COUNT); 201 return (prio <= PRI_HIGHEST_TS) ? 202 &ci_rq->r_ts_queue[prio].q_head : 203 &ci_rq->r_rt_queue[prio - PRI_HIGHEST_TS - 1].q_head; 204 } 205 206 void 207 sched_enqueue(struct lwp *l, bool swtch) 208 { 209 runqueue_t *ci_rq; 210 struct schedstate_percpu *spc; 211 TAILQ_HEAD(, lwp) *q_head; 212 const pri_t eprio = lwp_eprio(l); 213 struct cpu_info *ci; 214 int type; 215 216 ci = l->l_cpu; 217 spc = &ci->ci_schedstate; 218 ci_rq = spc->spc_sched_info; 219 KASSERT(lwp_locked(l, l->l_cpu->ci_schedstate.spc_mutex)); 220 221 /* Update the last run time on switch */ 222 if (__predict_true(swtch == true)) 223 l->l_rticksum += (hardclock_ticks - l->l_rticks); 224 else if (l->l_rticks == 0) 225 l->l_rticks = hardclock_ticks; 226 227 /* Enqueue the thread */ 228 q_head = sched_getrq(ci_rq, eprio); 229 if (TAILQ_EMPTY(q_head)) { 230 u_int i; 231 uint32_t q; 232 233 /* Mark bit */ 234 i = eprio >> BITMAP_SHIFT; 235 q = BITMAP_MSB >> (eprio & BITMAP_MASK); 236 KASSERT((ci_rq->r_bitmap[i] & q) == 0); 237 ci_rq->r_bitmap[i] |= q; 238 } 239 TAILQ_INSERT_TAIL(q_head, l, l_runq); 240 ci_rq->r_count++; 241 if ((l->l_pflag & LP_BOUND) == 0) 242 ci_rq->r_mcount++; 243 244 /* 245 * Update the value of highest priority in the runqueue, 246 * if priority of this thread is higher. 247 */ 248 if (eprio > spc->spc_maxpriority) 249 spc->spc_maxpriority = eprio; 250 251 sched_newts(l); 252 253 /* 254 * Wake the chosen CPU or cause a preemption if the newly 255 * enqueued thread has higher priority. Don't cause a 256 * preemption if the thread is yielding (swtch). 257 */ 258 if (!swtch && eprio > spc->spc_curpriority) { 259 if (eprio >= sched_kpreempt_pri) 260 type = RESCHED_KPREEMPT; 261 else if (eprio >= sched_upreempt_pri) 262 type = RESCHED_IMMED; 263 else 264 type = RESCHED_LAZY; 265 cpu_need_resched(ci, type); 266 } 267 } 268 269 void 270 sched_dequeue(struct lwp *l) 271 { 272 runqueue_t *ci_rq; 273 TAILQ_HEAD(, lwp) *q_head; 274 struct schedstate_percpu *spc; 275 const pri_t eprio = lwp_eprio(l); 276 277 spc = & l->l_cpu->ci_schedstate; 278 ci_rq = spc->spc_sched_info; 279 KASSERT(lwp_locked(l, spc->spc_mutex)); 280 281 KASSERT(eprio <= spc->spc_maxpriority); 282 KASSERT(ci_rq->r_bitmap[eprio >> BITMAP_SHIFT] != 0); 283 KASSERT(ci_rq->r_count > 0); 284 285 if (spc->spc_migrating == l) 286 spc->spc_migrating = NULL; 287 288 ci_rq->r_count--; 289 if ((l->l_pflag & LP_BOUND) == 0) 290 ci_rq->r_mcount--; 291 292 q_head = sched_getrq(ci_rq, eprio); 293 TAILQ_REMOVE(q_head, l, l_runq); 294 if (TAILQ_EMPTY(q_head)) { 295 u_int i; 296 uint32_t q; 297 298 /* Unmark bit */ 299 i = eprio >> BITMAP_SHIFT; 300 q = BITMAP_MSB >> (eprio & BITMAP_MASK); 301 KASSERT((ci_rq->r_bitmap[i] & q) != 0); 302 ci_rq->r_bitmap[i] &= ~q; 303 304 /* 305 * Update the value of highest priority in the runqueue, in a 306 * case it was a last thread in the queue of highest priority. 307 */ 308 if (eprio != spc->spc_maxpriority) 309 return; 310 311 do { 312 if (ci_rq->r_bitmap[i] != 0) { 313 q = ffs(ci_rq->r_bitmap[i]); 314 spc->spc_maxpriority = 315 (i << BITMAP_SHIFT) + (BITMAP_BITS - q); 316 return; 317 } 318 } while (i--); 319 320 /* If not found - set the lowest value */ 321 spc->spc_maxpriority = 0; 322 } 323 } 324 325 /* 326 * Migration and balancing. 327 */ 328 329 #ifdef MULTIPROCESSOR 330 331 /* Estimate if LWP is cache-hot */ 332 static inline bool 333 lwp_cache_hot(const struct lwp *l) 334 { 335 336 if (l->l_slptime || l->l_rticks == 0) 337 return false; 338 339 return (hardclock_ticks - l->l_rticks <= cacheht_time); 340 } 341 342 /* Check if LWP can migrate to the chosen CPU */ 343 static inline bool 344 sched_migratable(const struct lwp *l, struct cpu_info *ci) 345 { 346 const struct schedstate_percpu *spc = &ci->ci_schedstate; 347 KASSERT(lwp_locked(__UNCONST(l), NULL)); 348 349 /* CPU is offline */ 350 if (__predict_false(spc->spc_flags & SPCF_OFFLINE)) 351 return false; 352 353 /* Affinity bind */ 354 if (__predict_false(l->l_flag & LW_AFFINITY)) 355 return kcpuset_isset(cpu_index(ci), l->l_affinity); 356 357 /* Processor-set */ 358 return (spc->spc_psid == l->l_psid); 359 } 360 361 /* 362 * Estimate the migration of LWP to the other CPU. 363 * Take and return the CPU, if migration is needed. 364 */ 365 struct cpu_info * 366 sched_takecpu(struct lwp *l) 367 { 368 struct cpu_info *ci, *tci, *first, *next; 369 struct schedstate_percpu *spc; 370 runqueue_t *ci_rq, *ici_rq; 371 pri_t eprio, lpri, pri; 372 373 KASSERT(lwp_locked(l, NULL)); 374 375 ci = l->l_cpu; 376 spc = &ci->ci_schedstate; 377 ci_rq = spc->spc_sched_info; 378 379 /* 380 * If thread is strictly bound, do not estimate other CPUs. 381 * If CPU of this thread is idling - run there. 382 */ 383 if ((l->l_pflag & LP_BOUND) != 0 || ci_rq->r_count == 0) { 384 ci_rq->r_ev_stay.ev_count++; 385 return ci; 386 } 387 388 /* Stay if thread is cache-hot. */ 389 eprio = lwp_eprio(l); 390 if (__predict_true(l->l_stat != LSIDL) && 391 lwp_cache_hot(l) && eprio >= spc->spc_curpriority) { 392 ci_rq->r_ev_stay.ev_count++; 393 return ci; 394 } 395 396 /* Run on current CPU if priority of thread is higher */ 397 ci = curcpu(); 398 spc = &ci->ci_schedstate; 399 if (eprio > spc->spc_curpriority && sched_migratable(l, ci)) { 400 ci_rq->r_ev_localize.ev_count++; 401 return ci; 402 } 403 404 /* 405 * Look for the CPU with the lowest priority thread. In case of 406 * equal priority, choose the CPU with the fewest of threads. 407 */ 408 first = l->l_cpu; 409 ci = first; 410 tci = first; 411 lpri = PRI_COUNT; 412 do { 413 next = CIRCLEQ_LOOP_NEXT(&cpu_queue, ci, ci_data.cpu_qchain); 414 spc = &ci->ci_schedstate; 415 ici_rq = spc->spc_sched_info; 416 pri = max(spc->spc_curpriority, spc->spc_maxpriority); 417 if (pri > lpri) 418 continue; 419 420 if (pri == lpri && ci_rq->r_count < ici_rq->r_count) 421 continue; 422 423 if (!sched_migratable(l, ci)) 424 continue; 425 426 lpri = pri; 427 tci = ci; 428 ci_rq = ici_rq; 429 } while (ci = next, ci != first); 430 431 ci_rq = tci->ci_schedstate.spc_sched_info; 432 ci_rq->r_ev_push.ev_count++; 433 434 return tci; 435 } 436 437 /* 438 * Tries to catch an LWP from the runqueue of other CPU. 439 */ 440 static struct lwp * 441 sched_catchlwp(struct cpu_info *ci) 442 { 443 struct cpu_info *curci = curcpu(); 444 struct schedstate_percpu *spc; 445 TAILQ_HEAD(, lwp) *q_head; 446 runqueue_t *ci_rq; 447 struct lwp *l; 448 449 spc = &ci->ci_schedstate; 450 ci_rq = spc->spc_sched_info; 451 if (ci_rq->r_mcount < min_catch) { 452 spc_unlock(ci); 453 return NULL; 454 } 455 456 /* Take the highest priority thread */ 457 q_head = sched_getrq(ci_rq, spc->spc_maxpriority); 458 l = TAILQ_FIRST(q_head); 459 460 for (;;) { 461 /* Check the first and next result from the queue */ 462 if (l == NULL) 463 break; 464 KASSERT(l->l_stat == LSRUN); 465 KASSERT(l->l_flag & LW_INMEM); 466 467 /* Look for threads, whose are allowed to migrate */ 468 if ((l->l_pflag & LP_BOUND) || lwp_cache_hot(l) || 469 !sched_migratable(l, curci)) { 470 l = TAILQ_NEXT(l, l_runq); 471 continue; 472 } 473 474 /* Grab the thread, and move to the local run queue */ 475 sched_dequeue(l); 476 l->l_cpu = curci; 477 ci_rq->r_ev_pull.ev_count++; 478 lwp_unlock_to(l, curci->ci_schedstate.spc_mutex); 479 sched_enqueue(l, false); 480 return l; 481 } 482 spc_unlock(ci); 483 484 return l; 485 } 486 487 /* 488 * Periodical calculations for balancing. 489 */ 490 static void 491 sched_balance(void *nocallout) 492 { 493 struct cpu_info *ci, *hci; 494 runqueue_t *ci_rq; 495 CPU_INFO_ITERATOR cii; 496 u_int highest; 497 498 hci = curcpu(); 499 highest = 0; 500 501 /* Make lockless countings */ 502 for (CPU_INFO_FOREACH(cii, ci)) { 503 ci_rq = ci->ci_schedstate.spc_sched_info; 504 505 /* Average count of the threads */ 506 ci_rq->r_avgcount = (ci_rq->r_avgcount + ci_rq->r_mcount) >> 1; 507 508 /* Look for CPU with the highest average */ 509 if (ci_rq->r_avgcount > highest) { 510 hci = ci; 511 highest = ci_rq->r_avgcount; 512 } 513 } 514 515 /* Update the worker */ 516 worker_ci = hci; 517 518 if (nocallout == NULL) 519 callout_schedule(&balance_ch, balance_period); 520 } 521 522 /* 523 * Called from each CPU's idle loop. 524 */ 525 void 526 sched_idle(void) 527 { 528 struct cpu_info *ci = curcpu(), *tci = NULL; 529 struct schedstate_percpu *spc, *tspc; 530 runqueue_t *ci_rq; 531 bool dlock = false; 532 533 /* Check if there is a migrating LWP */ 534 spc = &ci->ci_schedstate; 535 if (spc->spc_migrating == NULL) 536 goto no_migration; 537 538 spc_lock(ci); 539 for (;;) { 540 struct lwp *l; 541 542 l = spc->spc_migrating; 543 if (l == NULL) 544 break; 545 546 /* 547 * If second attempt, and target CPU has changed, 548 * drop the old lock. 549 */ 550 if (dlock == true && tci != l->l_target_cpu) { 551 KASSERT(tci != NULL); 552 spc_unlock(tci); 553 dlock = false; 554 } 555 556 /* 557 * Nothing to do if destination has changed to the 558 * local CPU, or migration was done by other CPU. 559 */ 560 tci = l->l_target_cpu; 561 if (tci == NULL || tci == ci) { 562 spc->spc_migrating = NULL; 563 l->l_target_cpu = NULL; 564 break; 565 } 566 tspc = &tci->ci_schedstate; 567 568 /* 569 * Double-lock the runqueues. 570 * We do that only once. 571 */ 572 if (dlock == false) { 573 dlock = true; 574 if (ci < tci) { 575 spc_lock(tci); 576 } else if (!mutex_tryenter(tspc->spc_mutex)) { 577 spc_unlock(ci); 578 spc_lock(tci); 579 spc_lock(ci); 580 /* Check the situation again.. */ 581 continue; 582 } 583 } 584 585 /* Migrate the thread */ 586 KASSERT(l->l_stat == LSRUN); 587 spc->spc_migrating = NULL; 588 l->l_target_cpu = NULL; 589 sched_dequeue(l); 590 l->l_cpu = tci; 591 lwp_setlock(l, tspc->spc_mutex); 592 sched_enqueue(l, false); 593 break; 594 } 595 if (dlock == true) { 596 KASSERT(tci != NULL); 597 spc_unlock(tci); 598 } 599 spc_unlock(ci); 600 601 no_migration: 602 ci_rq = spc->spc_sched_info; 603 if ((spc->spc_flags & SPCF_OFFLINE) != 0 || ci_rq->r_count != 0) { 604 return; 605 } 606 607 /* Reset the counter, and call the balancer */ 608 ci_rq->r_avgcount = 0; 609 sched_balance(ci); 610 tci = worker_ci; 611 if (ci == tci) 612 return; 613 spc_dlock(ci, tci); 614 (void)sched_catchlwp(tci); 615 spc_unlock(ci); 616 } 617 618 #else 619 620 struct cpu_info * 621 sched_takecpu(struct lwp *l) 622 { 623 624 return l->l_cpu; 625 } 626 627 void 628 sched_idle(void) 629 { 630 631 } 632 #endif /* MULTIPROCESSOR */ 633 634 /* 635 * Scheduling statistics and balancing. 636 */ 637 void 638 sched_lwp_stats(struct lwp *l) 639 { 640 int batch; 641 642 KASSERT(lwp_locked(l, NULL)); 643 644 /* Update sleep time */ 645 if (l->l_stat == LSSLEEP || l->l_stat == LSSTOP || 646 l->l_stat == LSSUSPENDED) 647 l->l_slptime++; 648 649 /* 650 * Set that thread is more CPU-bound, if sum of run time exceeds the 651 * sum of sleep time. Check if thread is CPU-bound a first time. 652 */ 653 batch = (l->l_rticksum > l->l_slpticksum); 654 if (batch != 0) { 655 if ((l->l_flag & LW_BATCH) == 0) 656 batch = 0; 657 l->l_flag |= LW_BATCH; 658 } else 659 l->l_flag &= ~LW_BATCH; 660 661 /* 662 * If thread is CPU-bound and never sleeps, it would occupy the CPU. 663 * In such case reset the value of last sleep, and check it later, if 664 * it is still zero - perform the migration, unmark the batch flag. 665 */ 666 if (batch && (l->l_slptime + l->l_slpticksum) == 0) { 667 if (l->l_slpticks == 0) { 668 if (l->l_target_cpu == NULL && 669 (l->l_stat == LSRUN || l->l_stat == LSONPROC)) { 670 struct cpu_info *ci = sched_takecpu(l); 671 l->l_target_cpu = (ci != l->l_cpu) ? ci : NULL; 672 } 673 l->l_flag &= ~LW_BATCH; 674 } else { 675 l->l_slpticks = 0; 676 } 677 } 678 679 /* Reset the time sums */ 680 l->l_slpticksum = 0; 681 l->l_rticksum = 0; 682 683 /* Scheduler-specific hook */ 684 sched_pstats_hook(l, batch); 685 } 686 687 /* 688 * Scheduler mill. 689 */ 690 struct lwp * 691 sched_nextlwp(void) 692 { 693 struct cpu_info *ci = curcpu(); 694 struct schedstate_percpu *spc; 695 TAILQ_HEAD(, lwp) *q_head; 696 runqueue_t *ci_rq; 697 struct lwp *l; 698 699 /* Return to idle LWP if there is a migrating thread */ 700 spc = &ci->ci_schedstate; 701 if (__predict_false(spc->spc_migrating != NULL)) 702 return NULL; 703 ci_rq = spc->spc_sched_info; 704 705 #ifdef MULTIPROCESSOR 706 /* If runqueue is empty, try to catch some thread from other CPU */ 707 if (__predict_false(ci_rq->r_count == 0)) { 708 struct cpu_info *cci; 709 710 /* Offline CPUs should not perform this, however */ 711 if (__predict_false(spc->spc_flags & SPCF_OFFLINE)) 712 return NULL; 713 714 /* Reset the counter, and call the balancer */ 715 ci_rq->r_avgcount = 0; 716 sched_balance(ci); 717 cci = worker_ci; 718 if (ci == cci || !mutex_tryenter(cci->ci_schedstate.spc_mutex)) 719 return NULL; 720 return sched_catchlwp(cci); 721 } 722 #else 723 if (__predict_false(ci_rq->r_count == 0)) 724 return NULL; 725 #endif 726 727 /* Take the highest priority thread */ 728 KASSERT(ci_rq->r_bitmap[spc->spc_maxpriority >> BITMAP_SHIFT]); 729 q_head = sched_getrq(ci_rq, spc->spc_maxpriority); 730 l = TAILQ_FIRST(q_head); 731 KASSERT(l != NULL); 732 733 sched_oncpu(l); 734 l->l_rticks = hardclock_ticks; 735 736 return l; 737 } 738 739 bool 740 sched_curcpu_runnable_p(void) 741 { 742 const struct cpu_info *ci; 743 const struct schedstate_percpu *spc; 744 const runqueue_t *ci_rq; 745 bool rv; 746 747 kpreempt_disable(); 748 ci = curcpu(); 749 spc = &ci->ci_schedstate; 750 ci_rq = spc->spc_sched_info; 751 752 #ifndef __HAVE_FAST_SOFTINTS 753 if (ci->ci_data.cpu_softints) { 754 kpreempt_enable(); 755 return true; 756 } 757 #endif 758 759 rv = (ci_rq->r_count != 0) ? true : false; 760 kpreempt_enable(); 761 762 return rv; 763 } 764 765 /* 766 * Sysctl nodes and initialization. 767 */ 768 769 SYSCTL_SETUP(sysctl_sched_setup, "sysctl sched setup") 770 { 771 const struct sysctlnode *node = NULL; 772 773 sysctl_createv(clog, 0, NULL, NULL, 774 CTLFLAG_PERMANENT, 775 CTLTYPE_NODE, "kern", NULL, 776 NULL, 0, NULL, 0, 777 CTL_KERN, CTL_EOL); 778 sysctl_createv(clog, 0, NULL, &node, 779 CTLFLAG_PERMANENT, 780 CTLTYPE_NODE, "sched", 781 SYSCTL_DESCR("Scheduler options"), 782 NULL, 0, NULL, 0, 783 CTL_KERN, CTL_CREATE, CTL_EOL); 784 785 if (node == NULL) 786 return; 787 788 sysctl_createv(clog, 0, &node, NULL, 789 CTLFLAG_PERMANENT | CTLFLAG_READWRITE, 790 CTLTYPE_INT, "cacheht_time", 791 SYSCTL_DESCR("Cache hotness time (in ticks)"), 792 NULL, 0, &cacheht_time, 0, 793 CTL_CREATE, CTL_EOL); 794 sysctl_createv(clog, 0, &node, NULL, 795 CTLFLAG_PERMANENT | CTLFLAG_READWRITE, 796 CTLTYPE_INT, "balance_period", 797 SYSCTL_DESCR("Balance period (in ticks)"), 798 NULL, 0, &balance_period, 0, 799 CTL_CREATE, CTL_EOL); 800 sysctl_createv(clog, 0, &node, NULL, 801 CTLFLAG_PERMANENT | CTLFLAG_READWRITE, 802 CTLTYPE_INT, "min_catch", 803 SYSCTL_DESCR("Minimal count of threads for catching"), 804 NULL, 0, &min_catch, 0, 805 CTL_CREATE, CTL_EOL); 806 sysctl_createv(clog, 0, &node, NULL, 807 CTLFLAG_PERMANENT | CTLFLAG_READWRITE, 808 CTLTYPE_INT, "timesoftints", 809 SYSCTL_DESCR("Track CPU time for soft interrupts"), 810 NULL, 0, &softint_timing, 0, 811 CTL_CREATE, CTL_EOL); 812 sysctl_createv(clog, 0, &node, NULL, 813 CTLFLAG_PERMANENT | CTLFLAG_READWRITE, 814 CTLTYPE_INT, "kpreempt_pri", 815 SYSCTL_DESCR("Minimum priority to trigger kernel preemption"), 816 NULL, 0, &sched_kpreempt_pri, 0, 817 CTL_CREATE, CTL_EOL); 818 sysctl_createv(clog, 0, &node, NULL, 819 CTLFLAG_PERMANENT | CTLFLAG_READWRITE, 820 CTLTYPE_INT, "upreempt_pri", 821 SYSCTL_DESCR("Minimum priority to trigger user preemption"), 822 NULL, 0, &sched_upreempt_pri, 0, 823 CTL_CREATE, CTL_EOL); 824 } 825 826 /* 827 * Debugging. 828 */ 829 830 #ifdef DDB 831 832 void 833 sched_print_runqueue(void (*pr)(const char *, ...) 834 __attribute__((__format__(__printf__,1,2)))) 835 { 836 runqueue_t *ci_rq; 837 struct cpu_info *ci, *tci; 838 struct schedstate_percpu *spc; 839 struct lwp *l; 840 struct proc *p; 841 CPU_INFO_ITERATOR cii; 842 843 for (CPU_INFO_FOREACH(cii, ci)) { 844 int i; 845 846 spc = &ci->ci_schedstate; 847 ci_rq = spc->spc_sched_info; 848 849 (*pr)("Run-queue (CPU = %u):\n", ci->ci_index); 850 (*pr)(" pid.lid = %d.%d, r_count = %u, r_avgcount = %u, " 851 "maxpri = %d, mlwp = %p\n", 852 #ifdef MULTIPROCESSOR 853 ci->ci_curlwp->l_proc->p_pid, ci->ci_curlwp->l_lid, 854 #else 855 curlwp->l_proc->p_pid, curlwp->l_lid, 856 #endif 857 ci_rq->r_count, ci_rq->r_avgcount, spc->spc_maxpriority, 858 spc->spc_migrating); 859 i = (PRI_COUNT >> BITMAP_SHIFT) - 1; 860 do { 861 uint32_t q; 862 q = ci_rq->r_bitmap[i]; 863 (*pr)(" bitmap[%d] => [ %d (0x%x) ]\n", i, ffs(q), q); 864 } while (i--); 865 } 866 867 (*pr)(" %5s %4s %4s %10s %3s %18s %4s %4s %s\n", 868 "LID", "PRI", "EPRI", "FL", "ST", "LWP", "CPU", "TCI", "LRTICKS"); 869 870 PROCLIST_FOREACH(p, &allproc) { 871 if ((p->p_flag & PK_MARKER) != 0) 872 continue; 873 (*pr)(" /- %d (%s)\n", (int)p->p_pid, p->p_comm); 874 LIST_FOREACH(l, &p->p_lwps, l_sibling) { 875 ci = l->l_cpu; 876 tci = l->l_target_cpu; 877 (*pr)(" | %5d %4u %4u 0x%8.8x %3s %18p %4u %4d %u\n", 878 (int)l->l_lid, l->l_priority, lwp_eprio(l), 879 l->l_flag, l->l_stat == LSRUN ? "RQ" : 880 (l->l_stat == LSSLEEP ? "SQ" : "-"), 881 l, ci->ci_index, (tci ? tci->ci_index : -1), 882 (u_int)(hardclock_ticks - l->l_rticks)); 883 } 884 } 885 } 886 887 #endif 888