1 /* $NetBSD: kern_runq.c,v 1.16 2008/05/30 12:18:14 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 1.16 2008/05/30 12:18:14 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); /* ~300ms */ 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 = 0; 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; 347 348 /* CPU is offline */ 349 if (__predict_false(spc->spc_flags & SPCF_OFFLINE)) 350 return false; 351 352 /* Affinity bind */ 353 if (__predict_false(l->l_flag & LW_AFFINITY)) 354 return CPU_ISSET(cpu_index(ci), &l->l_affinity); 355 356 /* Processor-set */ 357 return (spc->spc_psid == l->l_psid); 358 } 359 360 /* 361 * Estimate the migration of LWP to the other CPU. 362 * Take and return the CPU, if migration is needed. 363 */ 364 struct cpu_info * 365 sched_takecpu(struct lwp *l) 366 { 367 struct cpu_info *ci, *tci, *first, *next; 368 struct schedstate_percpu *spc; 369 runqueue_t *ci_rq, *ici_rq; 370 pri_t eprio, lpri, pri; 371 372 KASSERT(lwp_locked(l, NULL)); 373 374 ci = l->l_cpu; 375 spc = &ci->ci_schedstate; 376 ci_rq = spc->spc_sched_info; 377 378 /* 379 * If thread is strictly bound, do not estimate other CPUs. 380 * If CPU of this thread is idling - run there. 381 */ 382 if ((l->l_pflag & LP_BOUND) != 0 || ci_rq->r_count == 0) { 383 ci_rq->r_ev_stay.ev_count++; 384 return ci; 385 } 386 387 /* Stay if thread is cache-hot. */ 388 eprio = lwp_eprio(l); 389 if (__predict_true(l->l_stat != LSIDL) && 390 lwp_cache_hot(l) && eprio >= spc->spc_curpriority) { 391 ci_rq->r_ev_stay.ev_count++; 392 return ci; 393 } 394 395 /* Run on current CPU if priority of thread is higher */ 396 ci = curcpu(); 397 spc = &ci->ci_schedstate; 398 if (eprio > spc->spc_curpriority && sched_migratable(l, ci)) { 399 ci_rq->r_ev_localize.ev_count++; 400 return ci; 401 } 402 403 /* 404 * Look for the CPU with the lowest priority thread. In case of 405 * equal priority, choose the CPU with the fewest of threads. 406 */ 407 first = l->l_cpu; 408 ci = first; 409 tci = first; 410 lpri = PRI_COUNT; 411 do { 412 next = CIRCLEQ_LOOP_NEXT(&cpu_queue, ci, ci_data.cpu_qchain); 413 spc = &ci->ci_schedstate; 414 ici_rq = spc->spc_sched_info; 415 pri = max(spc->spc_curpriority, spc->spc_maxpriority); 416 if (pri > lpri) 417 continue; 418 419 if (pri == lpri && ci_rq->r_count < ici_rq->r_count) 420 continue; 421 422 if (!sched_migratable(l, ci)) 423 continue; 424 425 lpri = pri; 426 tci = ci; 427 ci_rq = ici_rq; 428 } while (ci = next, ci != first); 429 430 ci_rq = tci->ci_schedstate.spc_sched_info; 431 ci_rq->r_ev_push.ev_count++; 432 433 return tci; 434 } 435 436 /* 437 * Tries to catch an LWP from the runqueue of other CPU. 438 */ 439 static struct lwp * 440 sched_catchlwp(struct cpu_info *ci) 441 { 442 struct cpu_info *curci = curcpu(); 443 struct schedstate_percpu *spc; 444 TAILQ_HEAD(, lwp) *q_head; 445 runqueue_t *ci_rq; 446 struct lwp *l; 447 448 spc = &ci->ci_schedstate; 449 ci_rq = spc->spc_sched_info; 450 if (ci_rq->r_mcount < min_catch) { 451 spc_unlock(ci); 452 return NULL; 453 } 454 455 /* Take the highest priority thread */ 456 q_head = sched_getrq(ci_rq, spc->spc_maxpriority); 457 l = TAILQ_FIRST(q_head); 458 459 for (;;) { 460 /* Check the first and next result from the queue */ 461 if (l == NULL) 462 break; 463 KASSERT(l->l_stat == LSRUN); 464 KASSERT(l->l_flag & LW_INMEM); 465 466 /* Look for threads, whose are allowed to migrate */ 467 if ((l->l_pflag & LP_BOUND) || lwp_cache_hot(l) || 468 !sched_migratable(l, curci)) { 469 l = TAILQ_NEXT(l, l_runq); 470 continue; 471 } 472 473 /* Grab the thread, and move to the local run queue */ 474 sched_dequeue(l); 475 l->l_cpu = curci; 476 ci_rq->r_ev_pull.ev_count++; 477 lwp_unlock_to(l, curci->ci_schedstate.spc_mutex); 478 sched_enqueue(l, false); 479 return l; 480 } 481 spc_unlock(ci); 482 483 return l; 484 } 485 486 /* 487 * Periodical calculations for balancing. 488 */ 489 static void 490 sched_balance(void *nocallout) 491 { 492 struct cpu_info *ci, *hci; 493 runqueue_t *ci_rq; 494 CPU_INFO_ITERATOR cii; 495 u_int highest; 496 497 hci = curcpu(); 498 highest = 0; 499 500 /* Make lockless countings */ 501 for (CPU_INFO_FOREACH(cii, ci)) { 502 ci_rq = ci->ci_schedstate.spc_sched_info; 503 504 /* Average count of the threads */ 505 ci_rq->r_avgcount = (ci_rq->r_avgcount + ci_rq->r_mcount) >> 1; 506 507 /* Look for CPU with the highest average */ 508 if (ci_rq->r_avgcount > highest) { 509 hci = ci; 510 highest = ci_rq->r_avgcount; 511 } 512 } 513 514 /* Update the worker */ 515 worker_ci = hci; 516 517 if (nocallout == NULL) 518 callout_schedule(&balance_ch, balance_period); 519 } 520 521 /* 522 * Called from each CPU's idle loop. 523 */ 524 void 525 sched_idle(void) 526 { 527 struct cpu_info *ci = curcpu(), *tci = NULL; 528 struct schedstate_percpu *spc, *tspc; 529 runqueue_t *ci_rq; 530 bool dlock = false; 531 532 /* Check if there is a migrating LWP */ 533 spc = &ci->ci_schedstate; 534 if (spc->spc_migrating == NULL) 535 goto no_migration; 536 537 spc_lock(ci); 538 for (;;) { 539 struct lwp *l; 540 541 l = spc->spc_migrating; 542 if (l == NULL) 543 break; 544 545 /* 546 * If second attempt, and target CPU has changed, 547 * drop the old lock. 548 */ 549 if (dlock == true && tci != l->l_target_cpu) { 550 KASSERT(tci != NULL); 551 spc_unlock(tci); 552 dlock = false; 553 } 554 555 /* 556 * Nothing to do if destination has changed to the 557 * local CPU, or migration was done by other CPU. 558 */ 559 tci = l->l_target_cpu; 560 if (tci == NULL || tci == ci) { 561 spc->spc_migrating = NULL; 562 l->l_target_cpu = NULL; 563 break; 564 } 565 tspc = &tci->ci_schedstate; 566 567 /* 568 * Double-lock the runqueues. 569 * We do that only once. 570 */ 571 if (dlock == false) { 572 dlock = true; 573 if (ci < tci) { 574 spc_lock(tci); 575 } else if (!mutex_tryenter(tspc->spc_mutex)) { 576 spc_unlock(ci); 577 spc_lock(tci); 578 spc_lock(ci); 579 /* Check the situation again.. */ 580 continue; 581 } 582 } 583 584 /* Migrate the thread */ 585 KASSERT(l->l_stat == LSRUN); 586 spc->spc_migrating = NULL; 587 l->l_target_cpu = NULL; 588 sched_dequeue(l); 589 l->l_cpu = tci; 590 lwp_setlock(l, tspc->spc_mutex); 591 sched_enqueue(l, false); 592 break; 593 } 594 if (dlock == true) { 595 KASSERT(tci != NULL); 596 spc_unlock(tci); 597 } 598 spc_unlock(ci); 599 600 no_migration: 601 ci_rq = spc->spc_sched_info; 602 if ((spc->spc_flags & SPCF_OFFLINE) != 0 || ci_rq->r_count != 0) { 603 return; 604 } 605 606 /* Reset the counter, and call the balancer */ 607 ci_rq->r_avgcount = 0; 608 sched_balance(ci); 609 tci = worker_ci; 610 if (ci == tci) 611 return; 612 spc_dlock(ci, tci); 613 (void)sched_catchlwp(tci); 614 spc_unlock(ci); 615 } 616 617 #else 618 619 struct cpu_info * 620 sched_takecpu(struct lwp *l) 621 { 622 623 return l->l_cpu; 624 } 625 626 void 627 sched_idle(void) 628 { 629 630 } 631 #endif /* MULTIPROCESSOR */ 632 633 /* 634 * Scheduling statistics and balancing. 635 */ 636 void 637 sched_lwp_stats(struct lwp *l) 638 { 639 int batch; 640 641 if (l->l_stat == LSSLEEP || l->l_stat == LSSTOP || 642 l->l_stat == LSSUSPENDED) 643 l->l_slptime++; 644 645 /* 646 * Set that thread is more CPU-bound, if sum of run time exceeds the 647 * sum of sleep time. Check if thread is CPU-bound a first time. 648 */ 649 batch = (l->l_rticksum > l->l_slpticksum); 650 if (batch != 0) { 651 if ((l->l_flag & LW_BATCH) == 0) 652 batch = 0; 653 l->l_flag |= LW_BATCH; 654 } else 655 l->l_flag &= ~LW_BATCH; 656 657 /* 658 * If thread is CPU-bound and never sleeps, it would occupy the CPU. 659 * In such case reset the value of last sleep, and check it later, if 660 * it is still zero - perform the migration, unmark the batch flag. 661 */ 662 if (batch && (l->l_slptime + l->l_slpticksum) == 0) { 663 if (l->l_slpticks == 0) { 664 if (l->l_target_cpu == NULL && 665 (l->l_stat == LSRUN || l->l_stat == LSONPROC)) { 666 struct cpu_info *ci = sched_takecpu(l); 667 l->l_target_cpu = (ci != l->l_cpu) ? ci : NULL; 668 } 669 l->l_flag &= ~LW_BATCH; 670 } else { 671 l->l_slpticks = 0; 672 } 673 } 674 675 /* Reset the time sums */ 676 l->l_slpticksum = 0; 677 l->l_rticksum = 0; 678 679 /* Scheduler-specific hook */ 680 sched_pstats_hook(l, batch); 681 } 682 683 /* 684 * Scheduler mill. 685 */ 686 struct lwp * 687 sched_nextlwp(void) 688 { 689 struct cpu_info *ci = curcpu(); 690 struct schedstate_percpu *spc; 691 TAILQ_HEAD(, lwp) *q_head; 692 runqueue_t *ci_rq; 693 struct lwp *l; 694 695 /* Return to idle LWP if there is a migrating thread */ 696 spc = &ci->ci_schedstate; 697 if (__predict_false(spc->spc_migrating != NULL)) 698 return NULL; 699 ci_rq = spc->spc_sched_info; 700 701 #ifdef MULTIPROCESSOR 702 /* If runqueue is empty, try to catch some thread from other CPU */ 703 if (__predict_false(spc->spc_flags & SPCF_OFFLINE)) { 704 if ((ci_rq->r_count - ci_rq->r_mcount) == 0) 705 return NULL; 706 } else if (ci_rq->r_count == 0) { 707 struct cpu_info *cci; 708 /* Reset the counter, and call the balancer */ 709 ci_rq->r_avgcount = 0; 710 sched_balance(ci); 711 cci = worker_ci; 712 if (ci == cci || !mutex_tryenter(cci->ci_schedstate.spc_mutex)) 713 return NULL; 714 return sched_catchlwp(cci); 715 } 716 #else 717 if (ci_rq->r_count == 0) 718 return NULL; 719 #endif 720 721 /* Take the highest priority thread */ 722 KASSERT(ci_rq->r_bitmap[spc->spc_maxpriority >> BITMAP_SHIFT]); 723 q_head = sched_getrq(ci_rq, spc->spc_maxpriority); 724 l = TAILQ_FIRST(q_head); 725 KASSERT(l != NULL); 726 727 sched_oncpu(l); 728 l->l_rticks = hardclock_ticks; 729 730 return l; 731 } 732 733 bool 734 sched_curcpu_runnable_p(void) 735 { 736 const struct cpu_info *ci; 737 const struct schedstate_percpu *spc; 738 const runqueue_t *ci_rq; 739 bool rv; 740 741 kpreempt_disable(); 742 ci = curcpu(); 743 spc = &ci->ci_schedstate; 744 ci_rq = spc->spc_sched_info; 745 746 #ifndef __HAVE_FAST_SOFTINTS 747 if (ci->ci_data.cpu_softints) { 748 kpreempt_enable(); 749 return true; 750 } 751 #endif 752 753 if (__predict_false(spc->spc_flags & SPCF_OFFLINE)) 754 rv = (ci_rq->r_count - ci_rq->r_mcount); 755 else 756 rv = ci_rq->r_count != 0; 757 kpreempt_enable(); 758 759 return rv; 760 } 761 762 /* 763 * Sysctl nodes and initialization. 764 */ 765 766 SYSCTL_SETUP(sysctl_sched_setup, "sysctl sched setup") 767 { 768 const struct sysctlnode *node = NULL; 769 770 sysctl_createv(clog, 0, NULL, NULL, 771 CTLFLAG_PERMANENT, 772 CTLTYPE_NODE, "kern", NULL, 773 NULL, 0, NULL, 0, 774 CTL_KERN, CTL_EOL); 775 sysctl_createv(clog, 0, NULL, &node, 776 CTLFLAG_PERMANENT, 777 CTLTYPE_NODE, "sched", 778 SYSCTL_DESCR("Scheduler options"), 779 NULL, 0, NULL, 0, 780 CTL_KERN, CTL_CREATE, CTL_EOL); 781 782 if (node == NULL) 783 return; 784 785 sysctl_createv(clog, 0, &node, NULL, 786 CTLFLAG_PERMANENT | CTLFLAG_READWRITE, 787 CTLTYPE_INT, "cacheht_time", 788 SYSCTL_DESCR("Cache hotness time (in ticks)"), 789 NULL, 0, &cacheht_time, 0, 790 CTL_CREATE, CTL_EOL); 791 sysctl_createv(clog, 0, &node, NULL, 792 CTLFLAG_PERMANENT | CTLFLAG_READWRITE, 793 CTLTYPE_INT, "balance_period", 794 SYSCTL_DESCR("Balance period (in ticks)"), 795 NULL, 0, &balance_period, 0, 796 CTL_CREATE, CTL_EOL); 797 sysctl_createv(clog, 0, &node, NULL, 798 CTLFLAG_PERMANENT | CTLFLAG_READWRITE, 799 CTLTYPE_INT, "min_catch", 800 SYSCTL_DESCR("Minimal count of threads for catching"), 801 NULL, 0, &min_catch, 0, 802 CTL_CREATE, CTL_EOL); 803 sysctl_createv(clog, 0, &node, NULL, 804 CTLFLAG_PERMANENT | CTLFLAG_READWRITE, 805 CTLTYPE_INT, "timesoftints", 806 SYSCTL_DESCR("Track CPU time for soft interrupts"), 807 NULL, 0, &softint_timing, 0, 808 CTL_CREATE, CTL_EOL); 809 sysctl_createv(clog, 0, &node, NULL, 810 CTLFLAG_PERMANENT | CTLFLAG_READWRITE, 811 CTLTYPE_INT, "kpreempt_pri", 812 SYSCTL_DESCR("Minimum priority to trigger kernel preemption"), 813 NULL, 0, &sched_kpreempt_pri, 0, 814 CTL_CREATE, CTL_EOL); 815 sysctl_createv(clog, 0, &node, NULL, 816 CTLFLAG_PERMANENT | CTLFLAG_READWRITE, 817 CTLTYPE_INT, "upreempt_pri", 818 SYSCTL_DESCR("Minimum priority to trigger user preemption"), 819 NULL, 0, &sched_upreempt_pri, 0, 820 CTL_CREATE, CTL_EOL); 821 } 822 823 /* 824 * Debugging. 825 */ 826 827 #ifdef DDB 828 829 void 830 sched_print_runqueue(void (*pr)(const char *, ...) 831 __attribute__((__format__(__printf__,1,2)))) 832 { 833 runqueue_t *ci_rq; 834 struct cpu_info *ci, *tci; 835 struct schedstate_percpu *spc; 836 struct lwp *l; 837 struct proc *p; 838 CPU_INFO_ITERATOR cii; 839 840 for (CPU_INFO_FOREACH(cii, ci)) { 841 int i; 842 843 spc = &ci->ci_schedstate; 844 ci_rq = spc->spc_sched_info; 845 846 (*pr)("Run-queue (CPU = %u):\n", ci->ci_index); 847 (*pr)(" pid.lid = %d.%d, r_count = %u, r_avgcount = %u, " 848 "maxpri = %d, mchain = %p\n", 849 #ifdef MULTIPROCESSOR 850 ci->ci_curlwp->l_proc->p_pid, ci->ci_curlwp->l_lid, 851 #else 852 curlwp->l_proc->p_pid, curlwp->l_lid, 853 #endif 854 ci_rq->r_count, ci_rq->r_avgcount, spc->spc_maxpriority, 855 spc->spc_migrating); 856 i = (PRI_COUNT >> BITMAP_SHIFT) - 1; 857 do { 858 uint32_t q; 859 q = ci_rq->r_bitmap[i]; 860 (*pr)(" bitmap[%d] => [ %d (0x%x) ]\n", i, ffs(q), q); 861 } while (i--); 862 } 863 864 (*pr)(" %5s %4s %4s %10s %3s %18s %4s %4s %s\n", 865 "LID", "PRI", "EPRI", "FL", "ST", "LWP", "CPU", "TCI", "LRTICKS"); 866 867 PROCLIST_FOREACH(p, &allproc) { 868 if ((p->p_flag & PK_MARKER) != 0) 869 continue; 870 (*pr)(" /- %d (%s)\n", (int)p->p_pid, p->p_comm); 871 LIST_FOREACH(l, &p->p_lwps, l_sibling) { 872 ci = l->l_cpu; 873 tci = l->l_target_cpu; 874 (*pr)(" | %5d %4u %4u 0x%8.8x %3s %18p %4u %4d %u\n", 875 (int)l->l_lid, l->l_priority, lwp_eprio(l), 876 l->l_flag, l->l_stat == LSRUN ? "RQ" : 877 (l->l_stat == LSSLEEP ? "SQ" : "-"), 878 l, ci->ci_index, (tci ? tci->ci_index : -1), 879 (u_int)(hardclock_ticks - l->l_rticks)); 880 } 881 } 882 } 883 884 #endif 885