1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * Scheduler topology setup/handling methods 4 */ 5 #include "sched.h" 6 7 DEFINE_MUTEX(sched_domains_mutex); 8 9 /* Protected by sched_domains_mutex: */ 10 static cpumask_var_t sched_domains_tmpmask; 11 static cpumask_var_t sched_domains_tmpmask2; 12 13 #ifdef CONFIG_SCHED_DEBUG 14 15 static int __init sched_debug_setup(char *str) 16 { 17 sched_debug_enabled = true; 18 19 return 0; 20 } 21 early_param("sched_debug", sched_debug_setup); 22 23 static inline bool sched_debug(void) 24 { 25 return sched_debug_enabled; 26 } 27 28 #define SD_FLAG(_name, mflags) [__##_name] = { .meta_flags = mflags, .name = #_name }, 29 const struct sd_flag_debug sd_flag_debug[] = { 30 #include <linux/sched/sd_flags.h> 31 }; 32 #undef SD_FLAG 33 34 static int sched_domain_debug_one(struct sched_domain *sd, int cpu, int level, 35 struct cpumask *groupmask) 36 { 37 struct sched_group *group = sd->groups; 38 unsigned long flags = sd->flags; 39 unsigned int idx; 40 41 cpumask_clear(groupmask); 42 43 printk(KERN_DEBUG "%*s domain-%d: ", level, "", level); 44 printk(KERN_CONT "span=%*pbl level=%s\n", 45 cpumask_pr_args(sched_domain_span(sd)), sd->name); 46 47 if (!cpumask_test_cpu(cpu, sched_domain_span(sd))) { 48 printk(KERN_ERR "ERROR: domain->span does not contain CPU%d\n", cpu); 49 } 50 if (group && !cpumask_test_cpu(cpu, sched_group_span(group))) { 51 printk(KERN_ERR "ERROR: domain->groups does not contain CPU%d\n", cpu); 52 } 53 54 for_each_set_bit(idx, &flags, __SD_FLAG_CNT) { 55 unsigned int flag = BIT(idx); 56 unsigned int meta_flags = sd_flag_debug[idx].meta_flags; 57 58 if ((meta_flags & SDF_SHARED_CHILD) && sd->child && 59 !(sd->child->flags & flag)) 60 printk(KERN_ERR "ERROR: flag %s set here but not in child\n", 61 sd_flag_debug[idx].name); 62 63 if ((meta_flags & SDF_SHARED_PARENT) && sd->parent && 64 !(sd->parent->flags & flag)) 65 printk(KERN_ERR "ERROR: flag %s set here but not in parent\n", 66 sd_flag_debug[idx].name); 67 } 68 69 printk(KERN_DEBUG "%*s groups:", level + 1, ""); 70 do { 71 if (!group) { 72 printk("\n"); 73 printk(KERN_ERR "ERROR: group is NULL\n"); 74 break; 75 } 76 77 if (!cpumask_weight(sched_group_span(group))) { 78 printk(KERN_CONT "\n"); 79 printk(KERN_ERR "ERROR: empty group\n"); 80 break; 81 } 82 83 if (!(sd->flags & SD_OVERLAP) && 84 cpumask_intersects(groupmask, sched_group_span(group))) { 85 printk(KERN_CONT "\n"); 86 printk(KERN_ERR "ERROR: repeated CPUs\n"); 87 break; 88 } 89 90 cpumask_or(groupmask, groupmask, sched_group_span(group)); 91 92 printk(KERN_CONT " %d:{ span=%*pbl", 93 group->sgc->id, 94 cpumask_pr_args(sched_group_span(group))); 95 96 if ((sd->flags & SD_OVERLAP) && 97 !cpumask_equal(group_balance_mask(group), sched_group_span(group))) { 98 printk(KERN_CONT " mask=%*pbl", 99 cpumask_pr_args(group_balance_mask(group))); 100 } 101 102 if (group->sgc->capacity != SCHED_CAPACITY_SCALE) 103 printk(KERN_CONT " cap=%lu", group->sgc->capacity); 104 105 if (group == sd->groups && sd->child && 106 !cpumask_equal(sched_domain_span(sd->child), 107 sched_group_span(group))) { 108 printk(KERN_ERR "ERROR: domain->groups does not match domain->child\n"); 109 } 110 111 printk(KERN_CONT " }"); 112 113 group = group->next; 114 115 if (group != sd->groups) 116 printk(KERN_CONT ","); 117 118 } while (group != sd->groups); 119 printk(KERN_CONT "\n"); 120 121 if (!cpumask_equal(sched_domain_span(sd), groupmask)) 122 printk(KERN_ERR "ERROR: groups don't span domain->span\n"); 123 124 if (sd->parent && 125 !cpumask_subset(groupmask, sched_domain_span(sd->parent))) 126 printk(KERN_ERR "ERROR: parent span is not a superset of domain->span\n"); 127 return 0; 128 } 129 130 static void sched_domain_debug(struct sched_domain *sd, int cpu) 131 { 132 int level = 0; 133 134 if (!sched_debug_enabled) 135 return; 136 137 if (!sd) { 138 printk(KERN_DEBUG "CPU%d attaching NULL sched-domain.\n", cpu); 139 return; 140 } 141 142 printk(KERN_DEBUG "CPU%d attaching sched-domain(s):\n", cpu); 143 144 for (;;) { 145 if (sched_domain_debug_one(sd, cpu, level, sched_domains_tmpmask)) 146 break; 147 level++; 148 sd = sd->parent; 149 if (!sd) 150 break; 151 } 152 } 153 #else /* !CONFIG_SCHED_DEBUG */ 154 155 # define sched_debug_enabled 0 156 # define sched_domain_debug(sd, cpu) do { } while (0) 157 static inline bool sched_debug(void) 158 { 159 return false; 160 } 161 #endif /* CONFIG_SCHED_DEBUG */ 162 163 /* Generate a mask of SD flags with the SDF_NEEDS_GROUPS metaflag */ 164 #define SD_FLAG(name, mflags) (name * !!((mflags) & SDF_NEEDS_GROUPS)) | 165 static const unsigned int SD_DEGENERATE_GROUPS_MASK = 166 #include <linux/sched/sd_flags.h> 167 0; 168 #undef SD_FLAG 169 170 static int sd_degenerate(struct sched_domain *sd) 171 { 172 if (cpumask_weight(sched_domain_span(sd)) == 1) 173 return 1; 174 175 /* Following flags need at least 2 groups */ 176 if ((sd->flags & SD_DEGENERATE_GROUPS_MASK) && 177 (sd->groups != sd->groups->next)) 178 return 0; 179 180 /* Following flags don't use groups */ 181 if (sd->flags & (SD_WAKE_AFFINE)) 182 return 0; 183 184 return 1; 185 } 186 187 static int 188 sd_parent_degenerate(struct sched_domain *sd, struct sched_domain *parent) 189 { 190 unsigned long cflags = sd->flags, pflags = parent->flags; 191 192 if (sd_degenerate(parent)) 193 return 1; 194 195 if (!cpumask_equal(sched_domain_span(sd), sched_domain_span(parent))) 196 return 0; 197 198 /* Flags needing groups don't count if only 1 group in parent */ 199 if (parent->groups == parent->groups->next) 200 pflags &= ~SD_DEGENERATE_GROUPS_MASK; 201 202 if (~cflags & pflags) 203 return 0; 204 205 return 1; 206 } 207 208 #if defined(CONFIG_ENERGY_MODEL) && defined(CONFIG_CPU_FREQ_GOV_SCHEDUTIL) 209 DEFINE_STATIC_KEY_FALSE(sched_energy_present); 210 unsigned int sysctl_sched_energy_aware = 1; 211 DEFINE_MUTEX(sched_energy_mutex); 212 bool sched_energy_update; 213 214 void rebuild_sched_domains_energy(void) 215 { 216 mutex_lock(&sched_energy_mutex); 217 sched_energy_update = true; 218 rebuild_sched_domains(); 219 sched_energy_update = false; 220 mutex_unlock(&sched_energy_mutex); 221 } 222 223 #ifdef CONFIG_PROC_SYSCTL 224 int sched_energy_aware_handler(struct ctl_table *table, int write, 225 void *buffer, size_t *lenp, loff_t *ppos) 226 { 227 int ret, state; 228 229 if (write && !capable(CAP_SYS_ADMIN)) 230 return -EPERM; 231 232 ret = proc_dointvec_minmax(table, write, buffer, lenp, ppos); 233 if (!ret && write) { 234 state = static_branch_unlikely(&sched_energy_present); 235 if (state != sysctl_sched_energy_aware) 236 rebuild_sched_domains_energy(); 237 } 238 239 return ret; 240 } 241 #endif 242 243 static void free_pd(struct perf_domain *pd) 244 { 245 struct perf_domain *tmp; 246 247 while (pd) { 248 tmp = pd->next; 249 kfree(pd); 250 pd = tmp; 251 } 252 } 253 254 static struct perf_domain *find_pd(struct perf_domain *pd, int cpu) 255 { 256 while (pd) { 257 if (cpumask_test_cpu(cpu, perf_domain_span(pd))) 258 return pd; 259 pd = pd->next; 260 } 261 262 return NULL; 263 } 264 265 static struct perf_domain *pd_init(int cpu) 266 { 267 struct em_perf_domain *obj = em_cpu_get(cpu); 268 struct perf_domain *pd; 269 270 if (!obj) { 271 if (sched_debug()) 272 pr_info("%s: no EM found for CPU%d\n", __func__, cpu); 273 return NULL; 274 } 275 276 pd = kzalloc(sizeof(*pd), GFP_KERNEL); 277 if (!pd) 278 return NULL; 279 pd->em_pd = obj; 280 281 return pd; 282 } 283 284 static void perf_domain_debug(const struct cpumask *cpu_map, 285 struct perf_domain *pd) 286 { 287 if (!sched_debug() || !pd) 288 return; 289 290 printk(KERN_DEBUG "root_domain %*pbl:", cpumask_pr_args(cpu_map)); 291 292 while (pd) { 293 printk(KERN_CONT " pd%d:{ cpus=%*pbl nr_pstate=%d }", 294 cpumask_first(perf_domain_span(pd)), 295 cpumask_pr_args(perf_domain_span(pd)), 296 em_pd_nr_perf_states(pd->em_pd)); 297 pd = pd->next; 298 } 299 300 printk(KERN_CONT "\n"); 301 } 302 303 static void destroy_perf_domain_rcu(struct rcu_head *rp) 304 { 305 struct perf_domain *pd; 306 307 pd = container_of(rp, struct perf_domain, rcu); 308 free_pd(pd); 309 } 310 311 static void sched_energy_set(bool has_eas) 312 { 313 if (!has_eas && static_branch_unlikely(&sched_energy_present)) { 314 if (sched_debug()) 315 pr_info("%s: stopping EAS\n", __func__); 316 static_branch_disable_cpuslocked(&sched_energy_present); 317 } else if (has_eas && !static_branch_unlikely(&sched_energy_present)) { 318 if (sched_debug()) 319 pr_info("%s: starting EAS\n", __func__); 320 static_branch_enable_cpuslocked(&sched_energy_present); 321 } 322 } 323 324 /* 325 * EAS can be used on a root domain if it meets all the following conditions: 326 * 1. an Energy Model (EM) is available; 327 * 2. the SD_ASYM_CPUCAPACITY flag is set in the sched_domain hierarchy. 328 * 3. no SMT is detected. 329 * 4. the EM complexity is low enough to keep scheduling overheads low; 330 * 5. schedutil is driving the frequency of all CPUs of the rd; 331 * 6. frequency invariance support is present; 332 * 333 * The complexity of the Energy Model is defined as: 334 * 335 * C = nr_pd * (nr_cpus + nr_ps) 336 * 337 * with parameters defined as: 338 * - nr_pd: the number of performance domains 339 * - nr_cpus: the number of CPUs 340 * - nr_ps: the sum of the number of performance states of all performance 341 * domains (for example, on a system with 2 performance domains, 342 * with 10 performance states each, nr_ps = 2 * 10 = 20). 343 * 344 * It is generally not a good idea to use such a model in the wake-up path on 345 * very complex platforms because of the associated scheduling overheads. The 346 * arbitrary constraint below prevents that. It makes EAS usable up to 16 CPUs 347 * with per-CPU DVFS and less than 8 performance states each, for example. 348 */ 349 #define EM_MAX_COMPLEXITY 2048 350 351 extern struct cpufreq_governor schedutil_gov; 352 static bool build_perf_domains(const struct cpumask *cpu_map) 353 { 354 int i, nr_pd = 0, nr_ps = 0, nr_cpus = cpumask_weight(cpu_map); 355 struct perf_domain *pd = NULL, *tmp; 356 int cpu = cpumask_first(cpu_map); 357 struct root_domain *rd = cpu_rq(cpu)->rd; 358 struct cpufreq_policy *policy; 359 struct cpufreq_governor *gov; 360 361 if (!sysctl_sched_energy_aware) 362 goto free; 363 364 /* EAS is enabled for asymmetric CPU capacity topologies. */ 365 if (!per_cpu(sd_asym_cpucapacity, cpu)) { 366 if (sched_debug()) { 367 pr_info("rd %*pbl: CPUs do not have asymmetric capacities\n", 368 cpumask_pr_args(cpu_map)); 369 } 370 goto free; 371 } 372 373 /* EAS definitely does *not* handle SMT */ 374 if (sched_smt_active()) { 375 pr_warn("rd %*pbl: Disabling EAS, SMT is not supported\n", 376 cpumask_pr_args(cpu_map)); 377 goto free; 378 } 379 380 if (!arch_scale_freq_invariant()) { 381 if (sched_debug()) { 382 pr_warn("rd %*pbl: Disabling EAS: frequency-invariant load tracking not yet supported", 383 cpumask_pr_args(cpu_map)); 384 } 385 goto free; 386 } 387 388 for_each_cpu(i, cpu_map) { 389 /* Skip already covered CPUs. */ 390 if (find_pd(pd, i)) 391 continue; 392 393 /* Do not attempt EAS if schedutil is not being used. */ 394 policy = cpufreq_cpu_get(i); 395 if (!policy) 396 goto free; 397 gov = policy->governor; 398 cpufreq_cpu_put(policy); 399 if (gov != &schedutil_gov) { 400 if (rd->pd) 401 pr_warn("rd %*pbl: Disabling EAS, schedutil is mandatory\n", 402 cpumask_pr_args(cpu_map)); 403 goto free; 404 } 405 406 /* Create the new pd and add it to the local list. */ 407 tmp = pd_init(i); 408 if (!tmp) 409 goto free; 410 tmp->next = pd; 411 pd = tmp; 412 413 /* 414 * Count performance domains and performance states for the 415 * complexity check. 416 */ 417 nr_pd++; 418 nr_ps += em_pd_nr_perf_states(pd->em_pd); 419 } 420 421 /* Bail out if the Energy Model complexity is too high. */ 422 if (nr_pd * (nr_ps + nr_cpus) > EM_MAX_COMPLEXITY) { 423 WARN(1, "rd %*pbl: Failed to start EAS, EM complexity is too high\n", 424 cpumask_pr_args(cpu_map)); 425 goto free; 426 } 427 428 perf_domain_debug(cpu_map, pd); 429 430 /* Attach the new list of performance domains to the root domain. */ 431 tmp = rd->pd; 432 rcu_assign_pointer(rd->pd, pd); 433 if (tmp) 434 call_rcu(&tmp->rcu, destroy_perf_domain_rcu); 435 436 return !!pd; 437 438 free: 439 free_pd(pd); 440 tmp = rd->pd; 441 rcu_assign_pointer(rd->pd, NULL); 442 if (tmp) 443 call_rcu(&tmp->rcu, destroy_perf_domain_rcu); 444 445 return false; 446 } 447 #else 448 static void free_pd(struct perf_domain *pd) { } 449 #endif /* CONFIG_ENERGY_MODEL && CONFIG_CPU_FREQ_GOV_SCHEDUTIL*/ 450 451 static void free_rootdomain(struct rcu_head *rcu) 452 { 453 struct root_domain *rd = container_of(rcu, struct root_domain, rcu); 454 455 cpupri_cleanup(&rd->cpupri); 456 cpudl_cleanup(&rd->cpudl); 457 free_cpumask_var(rd->dlo_mask); 458 free_cpumask_var(rd->rto_mask); 459 free_cpumask_var(rd->online); 460 free_cpumask_var(rd->span); 461 free_pd(rd->pd); 462 kfree(rd); 463 } 464 465 void rq_attach_root(struct rq *rq, struct root_domain *rd) 466 { 467 struct root_domain *old_rd = NULL; 468 unsigned long flags; 469 470 raw_spin_lock_irqsave(&rq->lock, flags); 471 472 if (rq->rd) { 473 old_rd = rq->rd; 474 475 if (cpumask_test_cpu(rq->cpu, old_rd->online)) 476 set_rq_offline(rq); 477 478 cpumask_clear_cpu(rq->cpu, old_rd->span); 479 480 /* 481 * If we dont want to free the old_rd yet then 482 * set old_rd to NULL to skip the freeing later 483 * in this function: 484 */ 485 if (!atomic_dec_and_test(&old_rd->refcount)) 486 old_rd = NULL; 487 } 488 489 atomic_inc(&rd->refcount); 490 rq->rd = rd; 491 492 cpumask_set_cpu(rq->cpu, rd->span); 493 if (cpumask_test_cpu(rq->cpu, cpu_active_mask)) 494 set_rq_online(rq); 495 496 raw_spin_unlock_irqrestore(&rq->lock, flags); 497 498 if (old_rd) 499 call_rcu(&old_rd->rcu, free_rootdomain); 500 } 501 502 void sched_get_rd(struct root_domain *rd) 503 { 504 atomic_inc(&rd->refcount); 505 } 506 507 void sched_put_rd(struct root_domain *rd) 508 { 509 if (!atomic_dec_and_test(&rd->refcount)) 510 return; 511 512 call_rcu(&rd->rcu, free_rootdomain); 513 } 514 515 static int init_rootdomain(struct root_domain *rd) 516 { 517 if (!zalloc_cpumask_var(&rd->span, GFP_KERNEL)) 518 goto out; 519 if (!zalloc_cpumask_var(&rd->online, GFP_KERNEL)) 520 goto free_span; 521 if (!zalloc_cpumask_var(&rd->dlo_mask, GFP_KERNEL)) 522 goto free_online; 523 if (!zalloc_cpumask_var(&rd->rto_mask, GFP_KERNEL)) 524 goto free_dlo_mask; 525 526 #ifdef HAVE_RT_PUSH_IPI 527 rd->rto_cpu = -1; 528 raw_spin_lock_init(&rd->rto_lock); 529 init_irq_work(&rd->rto_push_work, rto_push_irq_work_func); 530 #endif 531 532 rd->visit_gen = 0; 533 init_dl_bw(&rd->dl_bw); 534 if (cpudl_init(&rd->cpudl) != 0) 535 goto free_rto_mask; 536 537 if (cpupri_init(&rd->cpupri) != 0) 538 goto free_cpudl; 539 return 0; 540 541 free_cpudl: 542 cpudl_cleanup(&rd->cpudl); 543 free_rto_mask: 544 free_cpumask_var(rd->rto_mask); 545 free_dlo_mask: 546 free_cpumask_var(rd->dlo_mask); 547 free_online: 548 free_cpumask_var(rd->online); 549 free_span: 550 free_cpumask_var(rd->span); 551 out: 552 return -ENOMEM; 553 } 554 555 /* 556 * By default the system creates a single root-domain with all CPUs as 557 * members (mimicking the global state we have today). 558 */ 559 struct root_domain def_root_domain; 560 561 void init_defrootdomain(void) 562 { 563 init_rootdomain(&def_root_domain); 564 565 atomic_set(&def_root_domain.refcount, 1); 566 } 567 568 static struct root_domain *alloc_rootdomain(void) 569 { 570 struct root_domain *rd; 571 572 rd = kzalloc(sizeof(*rd), GFP_KERNEL); 573 if (!rd) 574 return NULL; 575 576 if (init_rootdomain(rd) != 0) { 577 kfree(rd); 578 return NULL; 579 } 580 581 return rd; 582 } 583 584 static void free_sched_groups(struct sched_group *sg, int free_sgc) 585 { 586 struct sched_group *tmp, *first; 587 588 if (!sg) 589 return; 590 591 first = sg; 592 do { 593 tmp = sg->next; 594 595 if (free_sgc && atomic_dec_and_test(&sg->sgc->ref)) 596 kfree(sg->sgc); 597 598 if (atomic_dec_and_test(&sg->ref)) 599 kfree(sg); 600 sg = tmp; 601 } while (sg != first); 602 } 603 604 static void destroy_sched_domain(struct sched_domain *sd) 605 { 606 /* 607 * A normal sched domain may have multiple group references, an 608 * overlapping domain, having private groups, only one. Iterate, 609 * dropping group/capacity references, freeing where none remain. 610 */ 611 free_sched_groups(sd->groups, 1); 612 613 if (sd->shared && atomic_dec_and_test(&sd->shared->ref)) 614 kfree(sd->shared); 615 kfree(sd); 616 } 617 618 static void destroy_sched_domains_rcu(struct rcu_head *rcu) 619 { 620 struct sched_domain *sd = container_of(rcu, struct sched_domain, rcu); 621 622 while (sd) { 623 struct sched_domain *parent = sd->parent; 624 destroy_sched_domain(sd); 625 sd = parent; 626 } 627 } 628 629 static void destroy_sched_domains(struct sched_domain *sd) 630 { 631 if (sd) 632 call_rcu(&sd->rcu, destroy_sched_domains_rcu); 633 } 634 635 /* 636 * Keep a special pointer to the highest sched_domain that has 637 * SD_SHARE_PKG_RESOURCE set (Last Level Cache Domain) for this 638 * allows us to avoid some pointer chasing select_idle_sibling(). 639 * 640 * Also keep a unique ID per domain (we use the first CPU number in 641 * the cpumask of the domain), this allows us to quickly tell if 642 * two CPUs are in the same cache domain, see cpus_share_cache(). 643 */ 644 DEFINE_PER_CPU(struct sched_domain __rcu *, sd_llc); 645 DEFINE_PER_CPU(int, sd_llc_size); 646 DEFINE_PER_CPU(int, sd_llc_id); 647 DEFINE_PER_CPU(struct sched_domain_shared __rcu *, sd_llc_shared); 648 DEFINE_PER_CPU(struct sched_domain __rcu *, sd_numa); 649 DEFINE_PER_CPU(struct sched_domain __rcu *, sd_asym_packing); 650 DEFINE_PER_CPU(struct sched_domain __rcu *, sd_asym_cpucapacity); 651 DEFINE_STATIC_KEY_FALSE(sched_asym_cpucapacity); 652 653 static void update_top_cache_domain(int cpu) 654 { 655 struct sched_domain_shared *sds = NULL; 656 struct sched_domain *sd; 657 int id = cpu; 658 int size = 1; 659 660 sd = highest_flag_domain(cpu, SD_SHARE_PKG_RESOURCES); 661 if (sd) { 662 id = cpumask_first(sched_domain_span(sd)); 663 size = cpumask_weight(sched_domain_span(sd)); 664 sds = sd->shared; 665 } 666 667 rcu_assign_pointer(per_cpu(sd_llc, cpu), sd); 668 per_cpu(sd_llc_size, cpu) = size; 669 per_cpu(sd_llc_id, cpu) = id; 670 rcu_assign_pointer(per_cpu(sd_llc_shared, cpu), sds); 671 672 sd = lowest_flag_domain(cpu, SD_NUMA); 673 rcu_assign_pointer(per_cpu(sd_numa, cpu), sd); 674 675 sd = highest_flag_domain(cpu, SD_ASYM_PACKING); 676 rcu_assign_pointer(per_cpu(sd_asym_packing, cpu), sd); 677 678 sd = lowest_flag_domain(cpu, SD_ASYM_CPUCAPACITY); 679 rcu_assign_pointer(per_cpu(sd_asym_cpucapacity, cpu), sd); 680 } 681 682 /* 683 * Attach the domain 'sd' to 'cpu' as its base domain. Callers must 684 * hold the hotplug lock. 685 */ 686 static void 687 cpu_attach_domain(struct sched_domain *sd, struct root_domain *rd, int cpu) 688 { 689 struct rq *rq = cpu_rq(cpu); 690 struct sched_domain *tmp; 691 int numa_distance = 0; 692 693 /* Remove the sched domains which do not contribute to scheduling. */ 694 for (tmp = sd; tmp; ) { 695 struct sched_domain *parent = tmp->parent; 696 if (!parent) 697 break; 698 699 if (sd_parent_degenerate(tmp, parent)) { 700 tmp->parent = parent->parent; 701 if (parent->parent) 702 parent->parent->child = tmp; 703 /* 704 * Transfer SD_PREFER_SIBLING down in case of a 705 * degenerate parent; the spans match for this 706 * so the property transfers. 707 */ 708 if (parent->flags & SD_PREFER_SIBLING) 709 tmp->flags |= SD_PREFER_SIBLING; 710 destroy_sched_domain(parent); 711 } else 712 tmp = tmp->parent; 713 } 714 715 if (sd && sd_degenerate(sd)) { 716 tmp = sd; 717 sd = sd->parent; 718 destroy_sched_domain(tmp); 719 if (sd) 720 sd->child = NULL; 721 } 722 723 for (tmp = sd; tmp; tmp = tmp->parent) 724 numa_distance += !!(tmp->flags & SD_NUMA); 725 726 /* 727 * FIXME: Diameter >=3 is misrepresented. 728 * 729 * Smallest diameter=3 topology is: 730 * 731 * node 0 1 2 3 732 * 0: 10 20 30 40 733 * 1: 20 10 20 30 734 * 2: 30 20 10 20 735 * 3: 40 30 20 10 736 * 737 * 0 --- 1 --- 2 --- 3 738 * 739 * NUMA-3 0-3 N/A N/A 0-3 740 * groups: {0-2},{1-3} {1-3},{0-2} 741 * 742 * NUMA-2 0-2 0-3 0-3 1-3 743 * groups: {0-1},{1-3} {0-2},{2-3} {1-3},{0-1} {2-3},{0-2} 744 * 745 * NUMA-1 0-1 0-2 1-3 2-3 746 * groups: {0},{1} {1},{2},{0} {2},{3},{1} {3},{2} 747 * 748 * NUMA-0 0 1 2 3 749 * 750 * The NUMA-2 groups for nodes 0 and 3 are obviously buggered, as the 751 * group span isn't a subset of the domain span. 752 */ 753 WARN_ONCE(numa_distance > 2, "Shortest NUMA path spans too many nodes\n"); 754 755 sched_domain_debug(sd, cpu); 756 757 rq_attach_root(rq, rd); 758 tmp = rq->sd; 759 rcu_assign_pointer(rq->sd, sd); 760 dirty_sched_domain_sysctl(cpu); 761 destroy_sched_domains(tmp); 762 763 update_top_cache_domain(cpu); 764 } 765 766 struct s_data { 767 struct sched_domain * __percpu *sd; 768 struct root_domain *rd; 769 }; 770 771 enum s_alloc { 772 sa_rootdomain, 773 sa_sd, 774 sa_sd_storage, 775 sa_none, 776 }; 777 778 /* 779 * Return the canonical balance CPU for this group, this is the first CPU 780 * of this group that's also in the balance mask. 781 * 782 * The balance mask are all those CPUs that could actually end up at this 783 * group. See build_balance_mask(). 784 * 785 * Also see should_we_balance(). 786 */ 787 int group_balance_cpu(struct sched_group *sg) 788 { 789 return cpumask_first(group_balance_mask(sg)); 790 } 791 792 793 /* 794 * NUMA topology (first read the regular topology blurb below) 795 * 796 * Given a node-distance table, for example: 797 * 798 * node 0 1 2 3 799 * 0: 10 20 30 20 800 * 1: 20 10 20 30 801 * 2: 30 20 10 20 802 * 3: 20 30 20 10 803 * 804 * which represents a 4 node ring topology like: 805 * 806 * 0 ----- 1 807 * | | 808 * | | 809 * | | 810 * 3 ----- 2 811 * 812 * We want to construct domains and groups to represent this. The way we go 813 * about doing this is to build the domains on 'hops'. For each NUMA level we 814 * construct the mask of all nodes reachable in @level hops. 815 * 816 * For the above NUMA topology that gives 3 levels: 817 * 818 * NUMA-2 0-3 0-3 0-3 0-3 819 * groups: {0-1,3},{1-3} {0-2},{0,2-3} {1-3},{0-1,3} {0,2-3},{0-2} 820 * 821 * NUMA-1 0-1,3 0-2 1-3 0,2-3 822 * groups: {0},{1},{3} {0},{1},{2} {1},{2},{3} {0},{2},{3} 823 * 824 * NUMA-0 0 1 2 3 825 * 826 * 827 * As can be seen; things don't nicely line up as with the regular topology. 828 * When we iterate a domain in child domain chunks some nodes can be 829 * represented multiple times -- hence the "overlap" naming for this part of 830 * the topology. 831 * 832 * In order to minimize this overlap, we only build enough groups to cover the 833 * domain. For instance Node-0 NUMA-2 would only get groups: 0-1,3 and 1-3. 834 * 835 * Because: 836 * 837 * - the first group of each domain is its child domain; this 838 * gets us the first 0-1,3 839 * - the only uncovered node is 2, who's child domain is 1-3. 840 * 841 * However, because of the overlap, computing a unique CPU for each group is 842 * more complicated. Consider for instance the groups of NODE-1 NUMA-2, both 843 * groups include the CPUs of Node-0, while those CPUs would not in fact ever 844 * end up at those groups (they would end up in group: 0-1,3). 845 * 846 * To correct this we have to introduce the group balance mask. This mask 847 * will contain those CPUs in the group that can reach this group given the 848 * (child) domain tree. 849 * 850 * With this we can once again compute balance_cpu and sched_group_capacity 851 * relations. 852 * 853 * XXX include words on how balance_cpu is unique and therefore can be 854 * used for sched_group_capacity links. 855 * 856 * 857 * Another 'interesting' topology is: 858 * 859 * node 0 1 2 3 860 * 0: 10 20 20 30 861 * 1: 20 10 20 20 862 * 2: 20 20 10 20 863 * 3: 30 20 20 10 864 * 865 * Which looks a little like: 866 * 867 * 0 ----- 1 868 * | / | 869 * | / | 870 * | / | 871 * 2 ----- 3 872 * 873 * This topology is asymmetric, nodes 1,2 are fully connected, but nodes 0,3 874 * are not. 875 * 876 * This leads to a few particularly weird cases where the sched_domain's are 877 * not of the same number for each CPU. Consider: 878 * 879 * NUMA-2 0-3 0-3 880 * groups: {0-2},{1-3} {1-3},{0-2} 881 * 882 * NUMA-1 0-2 0-3 0-3 1-3 883 * 884 * NUMA-0 0 1 2 3 885 * 886 */ 887 888 889 /* 890 * Build the balance mask; it contains only those CPUs that can arrive at this 891 * group and should be considered to continue balancing. 892 * 893 * We do this during the group creation pass, therefore the group information 894 * isn't complete yet, however since each group represents a (child) domain we 895 * can fully construct this using the sched_domain bits (which are already 896 * complete). 897 */ 898 static void 899 build_balance_mask(struct sched_domain *sd, struct sched_group *sg, struct cpumask *mask) 900 { 901 const struct cpumask *sg_span = sched_group_span(sg); 902 struct sd_data *sdd = sd->private; 903 struct sched_domain *sibling; 904 int i; 905 906 cpumask_clear(mask); 907 908 for_each_cpu(i, sg_span) { 909 sibling = *per_cpu_ptr(sdd->sd, i); 910 911 /* 912 * Can happen in the asymmetric case, where these siblings are 913 * unused. The mask will not be empty because those CPUs that 914 * do have the top domain _should_ span the domain. 915 */ 916 if (!sibling->child) 917 continue; 918 919 /* If we would not end up here, we can't continue from here */ 920 if (!cpumask_equal(sg_span, sched_domain_span(sibling->child))) 921 continue; 922 923 cpumask_set_cpu(i, mask); 924 } 925 926 /* We must not have empty masks here */ 927 WARN_ON_ONCE(cpumask_empty(mask)); 928 } 929 930 /* 931 * XXX: This creates per-node group entries; since the load-balancer will 932 * immediately access remote memory to construct this group's load-balance 933 * statistics having the groups node local is of dubious benefit. 934 */ 935 static struct sched_group * 936 build_group_from_child_sched_domain(struct sched_domain *sd, int cpu) 937 { 938 struct sched_group *sg; 939 struct cpumask *sg_span; 940 941 sg = kzalloc_node(sizeof(struct sched_group) + cpumask_size(), 942 GFP_KERNEL, cpu_to_node(cpu)); 943 944 if (!sg) 945 return NULL; 946 947 sg_span = sched_group_span(sg); 948 if (sd->child) 949 cpumask_copy(sg_span, sched_domain_span(sd->child)); 950 else 951 cpumask_copy(sg_span, sched_domain_span(sd)); 952 953 atomic_inc(&sg->ref); 954 return sg; 955 } 956 957 static void init_overlap_sched_group(struct sched_domain *sd, 958 struct sched_group *sg) 959 { 960 struct cpumask *mask = sched_domains_tmpmask2; 961 struct sd_data *sdd = sd->private; 962 struct cpumask *sg_span; 963 int cpu; 964 965 build_balance_mask(sd, sg, mask); 966 cpu = cpumask_first_and(sched_group_span(sg), mask); 967 968 sg->sgc = *per_cpu_ptr(sdd->sgc, cpu); 969 if (atomic_inc_return(&sg->sgc->ref) == 1) 970 cpumask_copy(group_balance_mask(sg), mask); 971 else 972 WARN_ON_ONCE(!cpumask_equal(group_balance_mask(sg), mask)); 973 974 /* 975 * Initialize sgc->capacity such that even if we mess up the 976 * domains and no possible iteration will get us here, we won't 977 * die on a /0 trap. 978 */ 979 sg_span = sched_group_span(sg); 980 sg->sgc->capacity = SCHED_CAPACITY_SCALE * cpumask_weight(sg_span); 981 sg->sgc->min_capacity = SCHED_CAPACITY_SCALE; 982 sg->sgc->max_capacity = SCHED_CAPACITY_SCALE; 983 } 984 985 static int 986 build_overlap_sched_groups(struct sched_domain *sd, int cpu) 987 { 988 struct sched_group *first = NULL, *last = NULL, *sg; 989 const struct cpumask *span = sched_domain_span(sd); 990 struct cpumask *covered = sched_domains_tmpmask; 991 struct sd_data *sdd = sd->private; 992 struct sched_domain *sibling; 993 int i; 994 995 cpumask_clear(covered); 996 997 for_each_cpu_wrap(i, span, cpu) { 998 struct cpumask *sg_span; 999 1000 if (cpumask_test_cpu(i, covered)) 1001 continue; 1002 1003 sibling = *per_cpu_ptr(sdd->sd, i); 1004 1005 /* 1006 * Asymmetric node setups can result in situations where the 1007 * domain tree is of unequal depth, make sure to skip domains 1008 * that already cover the entire range. 1009 * 1010 * In that case build_sched_domains() will have terminated the 1011 * iteration early and our sibling sd spans will be empty. 1012 * Domains should always include the CPU they're built on, so 1013 * check that. 1014 */ 1015 if (!cpumask_test_cpu(i, sched_domain_span(sibling))) 1016 continue; 1017 1018 sg = build_group_from_child_sched_domain(sibling, cpu); 1019 if (!sg) 1020 goto fail; 1021 1022 sg_span = sched_group_span(sg); 1023 cpumask_or(covered, covered, sg_span); 1024 1025 init_overlap_sched_group(sd, sg); 1026 1027 if (!first) 1028 first = sg; 1029 if (last) 1030 last->next = sg; 1031 last = sg; 1032 last->next = first; 1033 } 1034 sd->groups = first; 1035 1036 return 0; 1037 1038 fail: 1039 free_sched_groups(first, 0); 1040 1041 return -ENOMEM; 1042 } 1043 1044 1045 /* 1046 * Package topology (also see the load-balance blurb in fair.c) 1047 * 1048 * The scheduler builds a tree structure to represent a number of important 1049 * topology features. By default (default_topology[]) these include: 1050 * 1051 * - Simultaneous multithreading (SMT) 1052 * - Multi-Core Cache (MC) 1053 * - Package (DIE) 1054 * 1055 * Where the last one more or less denotes everything up to a NUMA node. 1056 * 1057 * The tree consists of 3 primary data structures: 1058 * 1059 * sched_domain -> sched_group -> sched_group_capacity 1060 * ^ ^ ^ ^ 1061 * `-' `-' 1062 * 1063 * The sched_domains are per-CPU and have a two way link (parent & child) and 1064 * denote the ever growing mask of CPUs belonging to that level of topology. 1065 * 1066 * Each sched_domain has a circular (double) linked list of sched_group's, each 1067 * denoting the domains of the level below (or individual CPUs in case of the 1068 * first domain level). The sched_group linked by a sched_domain includes the 1069 * CPU of that sched_domain [*]. 1070 * 1071 * Take for instance a 2 threaded, 2 core, 2 cache cluster part: 1072 * 1073 * CPU 0 1 2 3 4 5 6 7 1074 * 1075 * DIE [ ] 1076 * MC [ ] [ ] 1077 * SMT [ ] [ ] [ ] [ ] 1078 * 1079 * - or - 1080 * 1081 * DIE 0-7 0-7 0-7 0-7 0-7 0-7 0-7 0-7 1082 * MC 0-3 0-3 0-3 0-3 4-7 4-7 4-7 4-7 1083 * SMT 0-1 0-1 2-3 2-3 4-5 4-5 6-7 6-7 1084 * 1085 * CPU 0 1 2 3 4 5 6 7 1086 * 1087 * One way to think about it is: sched_domain moves you up and down among these 1088 * topology levels, while sched_group moves you sideways through it, at child 1089 * domain granularity. 1090 * 1091 * sched_group_capacity ensures each unique sched_group has shared storage. 1092 * 1093 * There are two related construction problems, both require a CPU that 1094 * uniquely identify each group (for a given domain): 1095 * 1096 * - The first is the balance_cpu (see should_we_balance() and the 1097 * load-balance blub in fair.c); for each group we only want 1 CPU to 1098 * continue balancing at a higher domain. 1099 * 1100 * - The second is the sched_group_capacity; we want all identical groups 1101 * to share a single sched_group_capacity. 1102 * 1103 * Since these topologies are exclusive by construction. That is, its 1104 * impossible for an SMT thread to belong to multiple cores, and cores to 1105 * be part of multiple caches. There is a very clear and unique location 1106 * for each CPU in the hierarchy. 1107 * 1108 * Therefore computing a unique CPU for each group is trivial (the iteration 1109 * mask is redundant and set all 1s; all CPUs in a group will end up at _that_ 1110 * group), we can simply pick the first CPU in each group. 1111 * 1112 * 1113 * [*] in other words, the first group of each domain is its child domain. 1114 */ 1115 1116 static struct sched_group *get_group(int cpu, struct sd_data *sdd) 1117 { 1118 struct sched_domain *sd = *per_cpu_ptr(sdd->sd, cpu); 1119 struct sched_domain *child = sd->child; 1120 struct sched_group *sg; 1121 bool already_visited; 1122 1123 if (child) 1124 cpu = cpumask_first(sched_domain_span(child)); 1125 1126 sg = *per_cpu_ptr(sdd->sg, cpu); 1127 sg->sgc = *per_cpu_ptr(sdd->sgc, cpu); 1128 1129 /* Increase refcounts for claim_allocations: */ 1130 already_visited = atomic_inc_return(&sg->ref) > 1; 1131 /* sgc visits should follow a similar trend as sg */ 1132 WARN_ON(already_visited != (atomic_inc_return(&sg->sgc->ref) > 1)); 1133 1134 /* If we have already visited that group, it's already initialized. */ 1135 if (already_visited) 1136 return sg; 1137 1138 if (child) { 1139 cpumask_copy(sched_group_span(sg), sched_domain_span(child)); 1140 cpumask_copy(group_balance_mask(sg), sched_group_span(sg)); 1141 } else { 1142 cpumask_set_cpu(cpu, sched_group_span(sg)); 1143 cpumask_set_cpu(cpu, group_balance_mask(sg)); 1144 } 1145 1146 sg->sgc->capacity = SCHED_CAPACITY_SCALE * cpumask_weight(sched_group_span(sg)); 1147 sg->sgc->min_capacity = SCHED_CAPACITY_SCALE; 1148 sg->sgc->max_capacity = SCHED_CAPACITY_SCALE; 1149 1150 return sg; 1151 } 1152 1153 /* 1154 * build_sched_groups will build a circular linked list of the groups 1155 * covered by the given span, will set each group's ->cpumask correctly, 1156 * and will initialize their ->sgc. 1157 * 1158 * Assumes the sched_domain tree is fully constructed 1159 */ 1160 static int 1161 build_sched_groups(struct sched_domain *sd, int cpu) 1162 { 1163 struct sched_group *first = NULL, *last = NULL; 1164 struct sd_data *sdd = sd->private; 1165 const struct cpumask *span = sched_domain_span(sd); 1166 struct cpumask *covered; 1167 int i; 1168 1169 lockdep_assert_held(&sched_domains_mutex); 1170 covered = sched_domains_tmpmask; 1171 1172 cpumask_clear(covered); 1173 1174 for_each_cpu_wrap(i, span, cpu) { 1175 struct sched_group *sg; 1176 1177 if (cpumask_test_cpu(i, covered)) 1178 continue; 1179 1180 sg = get_group(i, sdd); 1181 1182 cpumask_or(covered, covered, sched_group_span(sg)); 1183 1184 if (!first) 1185 first = sg; 1186 if (last) 1187 last->next = sg; 1188 last = sg; 1189 } 1190 last->next = first; 1191 sd->groups = first; 1192 1193 return 0; 1194 } 1195 1196 /* 1197 * Initialize sched groups cpu_capacity. 1198 * 1199 * cpu_capacity indicates the capacity of sched group, which is used while 1200 * distributing the load between different sched groups in a sched domain. 1201 * Typically cpu_capacity for all the groups in a sched domain will be same 1202 * unless there are asymmetries in the topology. If there are asymmetries, 1203 * group having more cpu_capacity will pickup more load compared to the 1204 * group having less cpu_capacity. 1205 */ 1206 static void init_sched_groups_capacity(int cpu, struct sched_domain *sd) 1207 { 1208 struct sched_group *sg = sd->groups; 1209 1210 WARN_ON(!sg); 1211 1212 do { 1213 int cpu, max_cpu = -1; 1214 1215 sg->group_weight = cpumask_weight(sched_group_span(sg)); 1216 1217 if (!(sd->flags & SD_ASYM_PACKING)) 1218 goto next; 1219 1220 for_each_cpu(cpu, sched_group_span(sg)) { 1221 if (max_cpu < 0) 1222 max_cpu = cpu; 1223 else if (sched_asym_prefer(cpu, max_cpu)) 1224 max_cpu = cpu; 1225 } 1226 sg->asym_prefer_cpu = max_cpu; 1227 1228 next: 1229 sg = sg->next; 1230 } while (sg != sd->groups); 1231 1232 if (cpu != group_balance_cpu(sg)) 1233 return; 1234 1235 update_group_capacity(sd, cpu); 1236 } 1237 1238 /* 1239 * Initializers for schedule domains 1240 * Non-inlined to reduce accumulated stack pressure in build_sched_domains() 1241 */ 1242 1243 static int default_relax_domain_level = -1; 1244 int sched_domain_level_max; 1245 1246 static int __init setup_relax_domain_level(char *str) 1247 { 1248 if (kstrtoint(str, 0, &default_relax_domain_level)) 1249 pr_warn("Unable to set relax_domain_level\n"); 1250 1251 return 1; 1252 } 1253 __setup("relax_domain_level=", setup_relax_domain_level); 1254 1255 static void set_domain_attribute(struct sched_domain *sd, 1256 struct sched_domain_attr *attr) 1257 { 1258 int request; 1259 1260 if (!attr || attr->relax_domain_level < 0) { 1261 if (default_relax_domain_level < 0) 1262 return; 1263 request = default_relax_domain_level; 1264 } else 1265 request = attr->relax_domain_level; 1266 1267 if (sd->level > request) { 1268 /* Turn off idle balance on this domain: */ 1269 sd->flags &= ~(SD_BALANCE_WAKE|SD_BALANCE_NEWIDLE); 1270 } 1271 } 1272 1273 static void __sdt_free(const struct cpumask *cpu_map); 1274 static int __sdt_alloc(const struct cpumask *cpu_map); 1275 1276 static void __free_domain_allocs(struct s_data *d, enum s_alloc what, 1277 const struct cpumask *cpu_map) 1278 { 1279 switch (what) { 1280 case sa_rootdomain: 1281 if (!atomic_read(&d->rd->refcount)) 1282 free_rootdomain(&d->rd->rcu); 1283 fallthrough; 1284 case sa_sd: 1285 free_percpu(d->sd); 1286 fallthrough; 1287 case sa_sd_storage: 1288 __sdt_free(cpu_map); 1289 fallthrough; 1290 case sa_none: 1291 break; 1292 } 1293 } 1294 1295 static enum s_alloc 1296 __visit_domain_allocation_hell(struct s_data *d, const struct cpumask *cpu_map) 1297 { 1298 memset(d, 0, sizeof(*d)); 1299 1300 if (__sdt_alloc(cpu_map)) 1301 return sa_sd_storage; 1302 d->sd = alloc_percpu(struct sched_domain *); 1303 if (!d->sd) 1304 return sa_sd_storage; 1305 d->rd = alloc_rootdomain(); 1306 if (!d->rd) 1307 return sa_sd; 1308 1309 return sa_rootdomain; 1310 } 1311 1312 /* 1313 * NULL the sd_data elements we've used to build the sched_domain and 1314 * sched_group structure so that the subsequent __free_domain_allocs() 1315 * will not free the data we're using. 1316 */ 1317 static void claim_allocations(int cpu, struct sched_domain *sd) 1318 { 1319 struct sd_data *sdd = sd->private; 1320 1321 WARN_ON_ONCE(*per_cpu_ptr(sdd->sd, cpu) != sd); 1322 *per_cpu_ptr(sdd->sd, cpu) = NULL; 1323 1324 if (atomic_read(&(*per_cpu_ptr(sdd->sds, cpu))->ref)) 1325 *per_cpu_ptr(sdd->sds, cpu) = NULL; 1326 1327 if (atomic_read(&(*per_cpu_ptr(sdd->sg, cpu))->ref)) 1328 *per_cpu_ptr(sdd->sg, cpu) = NULL; 1329 1330 if (atomic_read(&(*per_cpu_ptr(sdd->sgc, cpu))->ref)) 1331 *per_cpu_ptr(sdd->sgc, cpu) = NULL; 1332 } 1333 1334 #ifdef CONFIG_NUMA 1335 enum numa_topology_type sched_numa_topology_type; 1336 1337 static int sched_domains_numa_levels; 1338 static int sched_domains_curr_level; 1339 1340 int sched_max_numa_distance; 1341 static int *sched_domains_numa_distance; 1342 static struct cpumask ***sched_domains_numa_masks; 1343 int __read_mostly node_reclaim_distance = RECLAIM_DISTANCE; 1344 #endif 1345 1346 /* 1347 * SD_flags allowed in topology descriptions. 1348 * 1349 * These flags are purely descriptive of the topology and do not prescribe 1350 * behaviour. Behaviour is artificial and mapped in the below sd_init() 1351 * function: 1352 * 1353 * SD_SHARE_CPUCAPACITY - describes SMT topologies 1354 * SD_SHARE_PKG_RESOURCES - describes shared caches 1355 * SD_NUMA - describes NUMA topologies 1356 * 1357 * Odd one out, which beside describing the topology has a quirk also 1358 * prescribes the desired behaviour that goes along with it: 1359 * 1360 * SD_ASYM_PACKING - describes SMT quirks 1361 */ 1362 #define TOPOLOGY_SD_FLAGS \ 1363 (SD_SHARE_CPUCAPACITY | \ 1364 SD_SHARE_PKG_RESOURCES | \ 1365 SD_NUMA | \ 1366 SD_ASYM_PACKING) 1367 1368 static struct sched_domain * 1369 sd_init(struct sched_domain_topology_level *tl, 1370 const struct cpumask *cpu_map, 1371 struct sched_domain *child, int dflags, int cpu) 1372 { 1373 struct sd_data *sdd = &tl->data; 1374 struct sched_domain *sd = *per_cpu_ptr(sdd->sd, cpu); 1375 int sd_id, sd_weight, sd_flags = 0; 1376 1377 #ifdef CONFIG_NUMA 1378 /* 1379 * Ugly hack to pass state to sd_numa_mask()... 1380 */ 1381 sched_domains_curr_level = tl->numa_level; 1382 #endif 1383 1384 sd_weight = cpumask_weight(tl->mask(cpu)); 1385 1386 if (tl->sd_flags) 1387 sd_flags = (*tl->sd_flags)(); 1388 if (WARN_ONCE(sd_flags & ~TOPOLOGY_SD_FLAGS, 1389 "wrong sd_flags in topology description\n")) 1390 sd_flags &= TOPOLOGY_SD_FLAGS; 1391 1392 /* Apply detected topology flags */ 1393 sd_flags |= dflags; 1394 1395 *sd = (struct sched_domain){ 1396 .min_interval = sd_weight, 1397 .max_interval = 2*sd_weight, 1398 .busy_factor = 16, 1399 .imbalance_pct = 117, 1400 1401 .cache_nice_tries = 0, 1402 1403 .flags = 1*SD_BALANCE_NEWIDLE 1404 | 1*SD_BALANCE_EXEC 1405 | 1*SD_BALANCE_FORK 1406 | 0*SD_BALANCE_WAKE 1407 | 1*SD_WAKE_AFFINE 1408 | 0*SD_SHARE_CPUCAPACITY 1409 | 0*SD_SHARE_PKG_RESOURCES 1410 | 0*SD_SERIALIZE 1411 | 1*SD_PREFER_SIBLING 1412 | 0*SD_NUMA 1413 | sd_flags 1414 , 1415 1416 .last_balance = jiffies, 1417 .balance_interval = sd_weight, 1418 .max_newidle_lb_cost = 0, 1419 .next_decay_max_lb_cost = jiffies, 1420 .child = child, 1421 #ifdef CONFIG_SCHED_DEBUG 1422 .name = tl->name, 1423 #endif 1424 }; 1425 1426 cpumask_and(sched_domain_span(sd), cpu_map, tl->mask(cpu)); 1427 sd_id = cpumask_first(sched_domain_span(sd)); 1428 1429 /* 1430 * Convert topological properties into behaviour. 1431 */ 1432 1433 /* Don't attempt to spread across CPUs of different capacities. */ 1434 if ((sd->flags & SD_ASYM_CPUCAPACITY) && sd->child) 1435 sd->child->flags &= ~SD_PREFER_SIBLING; 1436 1437 if (sd->flags & SD_SHARE_CPUCAPACITY) { 1438 sd->imbalance_pct = 110; 1439 1440 } else if (sd->flags & SD_SHARE_PKG_RESOURCES) { 1441 sd->imbalance_pct = 117; 1442 sd->cache_nice_tries = 1; 1443 1444 #ifdef CONFIG_NUMA 1445 } else if (sd->flags & SD_NUMA) { 1446 sd->cache_nice_tries = 2; 1447 1448 sd->flags &= ~SD_PREFER_SIBLING; 1449 sd->flags |= SD_SERIALIZE; 1450 if (sched_domains_numa_distance[tl->numa_level] > node_reclaim_distance) { 1451 sd->flags &= ~(SD_BALANCE_EXEC | 1452 SD_BALANCE_FORK | 1453 SD_WAKE_AFFINE); 1454 } 1455 1456 #endif 1457 } else { 1458 sd->cache_nice_tries = 1; 1459 } 1460 1461 /* 1462 * For all levels sharing cache; connect a sched_domain_shared 1463 * instance. 1464 */ 1465 if (sd->flags & SD_SHARE_PKG_RESOURCES) { 1466 sd->shared = *per_cpu_ptr(sdd->sds, sd_id); 1467 atomic_inc(&sd->shared->ref); 1468 atomic_set(&sd->shared->nr_busy_cpus, sd_weight); 1469 } 1470 1471 sd->private = sdd; 1472 1473 return sd; 1474 } 1475 1476 /* 1477 * Topology list, bottom-up. 1478 */ 1479 static struct sched_domain_topology_level default_topology[] = { 1480 #ifdef CONFIG_SCHED_SMT 1481 { cpu_smt_mask, cpu_smt_flags, SD_INIT_NAME(SMT) }, 1482 #endif 1483 #ifdef CONFIG_SCHED_MC 1484 { cpu_coregroup_mask, cpu_core_flags, SD_INIT_NAME(MC) }, 1485 #endif 1486 { cpu_cpu_mask, SD_INIT_NAME(DIE) }, 1487 { NULL, }, 1488 }; 1489 1490 static struct sched_domain_topology_level *sched_domain_topology = 1491 default_topology; 1492 1493 #define for_each_sd_topology(tl) \ 1494 for (tl = sched_domain_topology; tl->mask; tl++) 1495 1496 void set_sched_topology(struct sched_domain_topology_level *tl) 1497 { 1498 if (WARN_ON_ONCE(sched_smp_initialized)) 1499 return; 1500 1501 sched_domain_topology = tl; 1502 } 1503 1504 #ifdef CONFIG_NUMA 1505 1506 static const struct cpumask *sd_numa_mask(int cpu) 1507 { 1508 return sched_domains_numa_masks[sched_domains_curr_level][cpu_to_node(cpu)]; 1509 } 1510 1511 static void sched_numa_warn(const char *str) 1512 { 1513 static int done = false; 1514 int i,j; 1515 1516 if (done) 1517 return; 1518 1519 done = true; 1520 1521 printk(KERN_WARNING "ERROR: %s\n\n", str); 1522 1523 for (i = 0; i < nr_node_ids; i++) { 1524 printk(KERN_WARNING " "); 1525 for (j = 0; j < nr_node_ids; j++) 1526 printk(KERN_CONT "%02d ", node_distance(i,j)); 1527 printk(KERN_CONT "\n"); 1528 } 1529 printk(KERN_WARNING "\n"); 1530 } 1531 1532 bool find_numa_distance(int distance) 1533 { 1534 int i; 1535 1536 if (distance == node_distance(0, 0)) 1537 return true; 1538 1539 for (i = 0; i < sched_domains_numa_levels; i++) { 1540 if (sched_domains_numa_distance[i] == distance) 1541 return true; 1542 } 1543 1544 return false; 1545 } 1546 1547 /* 1548 * A system can have three types of NUMA topology: 1549 * NUMA_DIRECT: all nodes are directly connected, or not a NUMA system 1550 * NUMA_GLUELESS_MESH: some nodes reachable through intermediary nodes 1551 * NUMA_BACKPLANE: nodes can reach other nodes through a backplane 1552 * 1553 * The difference between a glueless mesh topology and a backplane 1554 * topology lies in whether communication between not directly 1555 * connected nodes goes through intermediary nodes (where programs 1556 * could run), or through backplane controllers. This affects 1557 * placement of programs. 1558 * 1559 * The type of topology can be discerned with the following tests: 1560 * - If the maximum distance between any nodes is 1 hop, the system 1561 * is directly connected. 1562 * - If for two nodes A and B, located N > 1 hops away from each other, 1563 * there is an intermediary node C, which is < N hops away from both 1564 * nodes A and B, the system is a glueless mesh. 1565 */ 1566 static void init_numa_topology_type(void) 1567 { 1568 int a, b, c, n; 1569 1570 n = sched_max_numa_distance; 1571 1572 if (sched_domains_numa_levels <= 2) { 1573 sched_numa_topology_type = NUMA_DIRECT; 1574 return; 1575 } 1576 1577 for_each_online_node(a) { 1578 for_each_online_node(b) { 1579 /* Find two nodes furthest removed from each other. */ 1580 if (node_distance(a, b) < n) 1581 continue; 1582 1583 /* Is there an intermediary node between a and b? */ 1584 for_each_online_node(c) { 1585 if (node_distance(a, c) < n && 1586 node_distance(b, c) < n) { 1587 sched_numa_topology_type = 1588 NUMA_GLUELESS_MESH; 1589 return; 1590 } 1591 } 1592 1593 sched_numa_topology_type = NUMA_BACKPLANE; 1594 return; 1595 } 1596 } 1597 } 1598 1599 1600 #define NR_DISTANCE_VALUES (1 << DISTANCE_BITS) 1601 1602 void sched_init_numa(void) 1603 { 1604 struct sched_domain_topology_level *tl; 1605 unsigned long *distance_map; 1606 int nr_levels = 0; 1607 int i, j; 1608 1609 /* 1610 * O(nr_nodes^2) deduplicating selection sort -- in order to find the 1611 * unique distances in the node_distance() table. 1612 */ 1613 distance_map = bitmap_alloc(NR_DISTANCE_VALUES, GFP_KERNEL); 1614 if (!distance_map) 1615 return; 1616 1617 bitmap_zero(distance_map, NR_DISTANCE_VALUES); 1618 for (i = 0; i < nr_node_ids; i++) { 1619 for (j = 0; j < nr_node_ids; j++) { 1620 int distance = node_distance(i, j); 1621 1622 if (distance < LOCAL_DISTANCE || distance >= NR_DISTANCE_VALUES) { 1623 sched_numa_warn("Invalid distance value range"); 1624 return; 1625 } 1626 1627 bitmap_set(distance_map, distance, 1); 1628 } 1629 } 1630 /* 1631 * We can now figure out how many unique distance values there are and 1632 * allocate memory accordingly. 1633 */ 1634 nr_levels = bitmap_weight(distance_map, NR_DISTANCE_VALUES); 1635 1636 sched_domains_numa_distance = kcalloc(nr_levels, sizeof(int), GFP_KERNEL); 1637 if (!sched_domains_numa_distance) { 1638 bitmap_free(distance_map); 1639 return; 1640 } 1641 1642 for (i = 0, j = 0; i < nr_levels; i++, j++) { 1643 j = find_next_bit(distance_map, NR_DISTANCE_VALUES, j); 1644 sched_domains_numa_distance[i] = j; 1645 } 1646 1647 bitmap_free(distance_map); 1648 1649 /* 1650 * 'nr_levels' contains the number of unique distances 1651 * 1652 * The sched_domains_numa_distance[] array includes the actual distance 1653 * numbers. 1654 */ 1655 1656 /* 1657 * Here, we should temporarily reset sched_domains_numa_levels to 0. 1658 * If it fails to allocate memory for array sched_domains_numa_masks[][], 1659 * the array will contain less then 'nr_levels' members. This could be 1660 * dangerous when we use it to iterate array sched_domains_numa_masks[][] 1661 * in other functions. 1662 * 1663 * We reset it to 'nr_levels' at the end of this function. 1664 */ 1665 sched_domains_numa_levels = 0; 1666 1667 sched_domains_numa_masks = kzalloc(sizeof(void *) * nr_levels, GFP_KERNEL); 1668 if (!sched_domains_numa_masks) 1669 return; 1670 1671 /* 1672 * Now for each level, construct a mask per node which contains all 1673 * CPUs of nodes that are that many hops away from us. 1674 */ 1675 for (i = 0; i < nr_levels; i++) { 1676 sched_domains_numa_masks[i] = 1677 kzalloc(nr_node_ids * sizeof(void *), GFP_KERNEL); 1678 if (!sched_domains_numa_masks[i]) 1679 return; 1680 1681 for (j = 0; j < nr_node_ids; j++) { 1682 struct cpumask *mask = kzalloc(cpumask_size(), GFP_KERNEL); 1683 int k; 1684 1685 if (!mask) 1686 return; 1687 1688 sched_domains_numa_masks[i][j] = mask; 1689 1690 for_each_node(k) { 1691 if (sched_debug() && (node_distance(j, k) != node_distance(k, j))) 1692 sched_numa_warn("Node-distance not symmetric"); 1693 1694 if (node_distance(j, k) > sched_domains_numa_distance[i]) 1695 continue; 1696 1697 cpumask_or(mask, mask, cpumask_of_node(k)); 1698 } 1699 } 1700 } 1701 1702 /* Compute default topology size */ 1703 for (i = 0; sched_domain_topology[i].mask; i++); 1704 1705 tl = kzalloc((i + nr_levels + 1) * 1706 sizeof(struct sched_domain_topology_level), GFP_KERNEL); 1707 if (!tl) 1708 return; 1709 1710 /* 1711 * Copy the default topology bits.. 1712 */ 1713 for (i = 0; sched_domain_topology[i].mask; i++) 1714 tl[i] = sched_domain_topology[i]; 1715 1716 /* 1717 * Add the NUMA identity distance, aka single NODE. 1718 */ 1719 tl[i++] = (struct sched_domain_topology_level){ 1720 .mask = sd_numa_mask, 1721 .numa_level = 0, 1722 SD_INIT_NAME(NODE) 1723 }; 1724 1725 /* 1726 * .. and append 'j' levels of NUMA goodness. 1727 */ 1728 for (j = 1; j < nr_levels; i++, j++) { 1729 tl[i] = (struct sched_domain_topology_level){ 1730 .mask = sd_numa_mask, 1731 .sd_flags = cpu_numa_flags, 1732 .flags = SDTL_OVERLAP, 1733 .numa_level = j, 1734 SD_INIT_NAME(NUMA) 1735 }; 1736 } 1737 1738 sched_domain_topology = tl; 1739 1740 sched_domains_numa_levels = nr_levels; 1741 sched_max_numa_distance = sched_domains_numa_distance[nr_levels - 1]; 1742 1743 init_numa_topology_type(); 1744 } 1745 1746 void sched_domains_numa_masks_set(unsigned int cpu) 1747 { 1748 int node = cpu_to_node(cpu); 1749 int i, j; 1750 1751 for (i = 0; i < sched_domains_numa_levels; i++) { 1752 for (j = 0; j < nr_node_ids; j++) { 1753 if (node_distance(j, node) <= sched_domains_numa_distance[i]) 1754 cpumask_set_cpu(cpu, sched_domains_numa_masks[i][j]); 1755 } 1756 } 1757 } 1758 1759 void sched_domains_numa_masks_clear(unsigned int cpu) 1760 { 1761 int i, j; 1762 1763 for (i = 0; i < sched_domains_numa_levels; i++) { 1764 for (j = 0; j < nr_node_ids; j++) 1765 cpumask_clear_cpu(cpu, sched_domains_numa_masks[i][j]); 1766 } 1767 } 1768 1769 /* 1770 * sched_numa_find_closest() - given the NUMA topology, find the cpu 1771 * closest to @cpu from @cpumask. 1772 * cpumask: cpumask to find a cpu from 1773 * cpu: cpu to be close to 1774 * 1775 * returns: cpu, or nr_cpu_ids when nothing found. 1776 */ 1777 int sched_numa_find_closest(const struct cpumask *cpus, int cpu) 1778 { 1779 int i, j = cpu_to_node(cpu); 1780 1781 for (i = 0; i < sched_domains_numa_levels; i++) { 1782 cpu = cpumask_any_and(cpus, sched_domains_numa_masks[i][j]); 1783 if (cpu < nr_cpu_ids) 1784 return cpu; 1785 } 1786 return nr_cpu_ids; 1787 } 1788 1789 #endif /* CONFIG_NUMA */ 1790 1791 static int __sdt_alloc(const struct cpumask *cpu_map) 1792 { 1793 struct sched_domain_topology_level *tl; 1794 int j; 1795 1796 for_each_sd_topology(tl) { 1797 struct sd_data *sdd = &tl->data; 1798 1799 sdd->sd = alloc_percpu(struct sched_domain *); 1800 if (!sdd->sd) 1801 return -ENOMEM; 1802 1803 sdd->sds = alloc_percpu(struct sched_domain_shared *); 1804 if (!sdd->sds) 1805 return -ENOMEM; 1806 1807 sdd->sg = alloc_percpu(struct sched_group *); 1808 if (!sdd->sg) 1809 return -ENOMEM; 1810 1811 sdd->sgc = alloc_percpu(struct sched_group_capacity *); 1812 if (!sdd->sgc) 1813 return -ENOMEM; 1814 1815 for_each_cpu(j, cpu_map) { 1816 struct sched_domain *sd; 1817 struct sched_domain_shared *sds; 1818 struct sched_group *sg; 1819 struct sched_group_capacity *sgc; 1820 1821 sd = kzalloc_node(sizeof(struct sched_domain) + cpumask_size(), 1822 GFP_KERNEL, cpu_to_node(j)); 1823 if (!sd) 1824 return -ENOMEM; 1825 1826 *per_cpu_ptr(sdd->sd, j) = sd; 1827 1828 sds = kzalloc_node(sizeof(struct sched_domain_shared), 1829 GFP_KERNEL, cpu_to_node(j)); 1830 if (!sds) 1831 return -ENOMEM; 1832 1833 *per_cpu_ptr(sdd->sds, j) = sds; 1834 1835 sg = kzalloc_node(sizeof(struct sched_group) + cpumask_size(), 1836 GFP_KERNEL, cpu_to_node(j)); 1837 if (!sg) 1838 return -ENOMEM; 1839 1840 sg->next = sg; 1841 1842 *per_cpu_ptr(sdd->sg, j) = sg; 1843 1844 sgc = kzalloc_node(sizeof(struct sched_group_capacity) + cpumask_size(), 1845 GFP_KERNEL, cpu_to_node(j)); 1846 if (!sgc) 1847 return -ENOMEM; 1848 1849 #ifdef CONFIG_SCHED_DEBUG 1850 sgc->id = j; 1851 #endif 1852 1853 *per_cpu_ptr(sdd->sgc, j) = sgc; 1854 } 1855 } 1856 1857 return 0; 1858 } 1859 1860 static void __sdt_free(const struct cpumask *cpu_map) 1861 { 1862 struct sched_domain_topology_level *tl; 1863 int j; 1864 1865 for_each_sd_topology(tl) { 1866 struct sd_data *sdd = &tl->data; 1867 1868 for_each_cpu(j, cpu_map) { 1869 struct sched_domain *sd; 1870 1871 if (sdd->sd) { 1872 sd = *per_cpu_ptr(sdd->sd, j); 1873 if (sd && (sd->flags & SD_OVERLAP)) 1874 free_sched_groups(sd->groups, 0); 1875 kfree(*per_cpu_ptr(sdd->sd, j)); 1876 } 1877 1878 if (sdd->sds) 1879 kfree(*per_cpu_ptr(sdd->sds, j)); 1880 if (sdd->sg) 1881 kfree(*per_cpu_ptr(sdd->sg, j)); 1882 if (sdd->sgc) 1883 kfree(*per_cpu_ptr(sdd->sgc, j)); 1884 } 1885 free_percpu(sdd->sd); 1886 sdd->sd = NULL; 1887 free_percpu(sdd->sds); 1888 sdd->sds = NULL; 1889 free_percpu(sdd->sg); 1890 sdd->sg = NULL; 1891 free_percpu(sdd->sgc); 1892 sdd->sgc = NULL; 1893 } 1894 } 1895 1896 static struct sched_domain *build_sched_domain(struct sched_domain_topology_level *tl, 1897 const struct cpumask *cpu_map, struct sched_domain_attr *attr, 1898 struct sched_domain *child, int dflags, int cpu) 1899 { 1900 struct sched_domain *sd = sd_init(tl, cpu_map, child, dflags, cpu); 1901 1902 if (child) { 1903 sd->level = child->level + 1; 1904 sched_domain_level_max = max(sched_domain_level_max, sd->level); 1905 child->parent = sd; 1906 1907 if (!cpumask_subset(sched_domain_span(child), 1908 sched_domain_span(sd))) { 1909 pr_err("BUG: arch topology borken\n"); 1910 #ifdef CONFIG_SCHED_DEBUG 1911 pr_err(" the %s domain not a subset of the %s domain\n", 1912 child->name, sd->name); 1913 #endif 1914 /* Fixup, ensure @sd has at least @child CPUs. */ 1915 cpumask_or(sched_domain_span(sd), 1916 sched_domain_span(sd), 1917 sched_domain_span(child)); 1918 } 1919 1920 } 1921 set_domain_attribute(sd, attr); 1922 1923 return sd; 1924 } 1925 1926 /* 1927 * Ensure topology masks are sane, i.e. there are no conflicts (overlaps) for 1928 * any two given CPUs at this (non-NUMA) topology level. 1929 */ 1930 static bool topology_span_sane(struct sched_domain_topology_level *tl, 1931 const struct cpumask *cpu_map, int cpu) 1932 { 1933 int i; 1934 1935 /* NUMA levels are allowed to overlap */ 1936 if (tl->flags & SDTL_OVERLAP) 1937 return true; 1938 1939 /* 1940 * Non-NUMA levels cannot partially overlap - they must be either 1941 * completely equal or completely disjoint. Otherwise we can end up 1942 * breaking the sched_group lists - i.e. a later get_group() pass 1943 * breaks the linking done for an earlier span. 1944 */ 1945 for_each_cpu(i, cpu_map) { 1946 if (i == cpu) 1947 continue; 1948 /* 1949 * We should 'and' all those masks with 'cpu_map' to exactly 1950 * match the topology we're about to build, but that can only 1951 * remove CPUs, which only lessens our ability to detect 1952 * overlaps 1953 */ 1954 if (!cpumask_equal(tl->mask(cpu), tl->mask(i)) && 1955 cpumask_intersects(tl->mask(cpu), tl->mask(i))) 1956 return false; 1957 } 1958 1959 return true; 1960 } 1961 1962 /* 1963 * Find the sched_domain_topology_level where all CPU capacities are visible 1964 * for all CPUs. 1965 */ 1966 static struct sched_domain_topology_level 1967 *asym_cpu_capacity_level(const struct cpumask *cpu_map) 1968 { 1969 int i, j, asym_level = 0; 1970 bool asym = false; 1971 struct sched_domain_topology_level *tl, *asym_tl = NULL; 1972 unsigned long cap; 1973 1974 /* Is there any asymmetry? */ 1975 cap = arch_scale_cpu_capacity(cpumask_first(cpu_map)); 1976 1977 for_each_cpu(i, cpu_map) { 1978 if (arch_scale_cpu_capacity(i) != cap) { 1979 asym = true; 1980 break; 1981 } 1982 } 1983 1984 if (!asym) 1985 return NULL; 1986 1987 /* 1988 * Examine topology from all CPU's point of views to detect the lowest 1989 * sched_domain_topology_level where a highest capacity CPU is visible 1990 * to everyone. 1991 */ 1992 for_each_cpu(i, cpu_map) { 1993 unsigned long max_capacity = arch_scale_cpu_capacity(i); 1994 int tl_id = 0; 1995 1996 for_each_sd_topology(tl) { 1997 if (tl_id < asym_level) 1998 goto next_level; 1999 2000 for_each_cpu_and(j, tl->mask(i), cpu_map) { 2001 unsigned long capacity; 2002 2003 capacity = arch_scale_cpu_capacity(j); 2004 2005 if (capacity <= max_capacity) 2006 continue; 2007 2008 max_capacity = capacity; 2009 asym_level = tl_id; 2010 asym_tl = tl; 2011 } 2012 next_level: 2013 tl_id++; 2014 } 2015 } 2016 2017 return asym_tl; 2018 } 2019 2020 2021 /* 2022 * Build sched domains for a given set of CPUs and attach the sched domains 2023 * to the individual CPUs 2024 */ 2025 static int 2026 build_sched_domains(const struct cpumask *cpu_map, struct sched_domain_attr *attr) 2027 { 2028 enum s_alloc alloc_state = sa_none; 2029 struct sched_domain *sd; 2030 struct s_data d; 2031 struct rq *rq = NULL; 2032 int i, ret = -ENOMEM; 2033 struct sched_domain_topology_level *tl_asym; 2034 bool has_asym = false; 2035 2036 if (WARN_ON(cpumask_empty(cpu_map))) 2037 goto error; 2038 2039 alloc_state = __visit_domain_allocation_hell(&d, cpu_map); 2040 if (alloc_state != sa_rootdomain) 2041 goto error; 2042 2043 tl_asym = asym_cpu_capacity_level(cpu_map); 2044 2045 /* Set up domains for CPUs specified by the cpu_map: */ 2046 for_each_cpu(i, cpu_map) { 2047 struct sched_domain_topology_level *tl; 2048 int dflags = 0; 2049 2050 sd = NULL; 2051 for_each_sd_topology(tl) { 2052 if (tl == tl_asym) { 2053 dflags |= SD_ASYM_CPUCAPACITY; 2054 has_asym = true; 2055 } 2056 2057 if (WARN_ON(!topology_span_sane(tl, cpu_map, i))) 2058 goto error; 2059 2060 sd = build_sched_domain(tl, cpu_map, attr, sd, dflags, i); 2061 2062 if (tl == sched_domain_topology) 2063 *per_cpu_ptr(d.sd, i) = sd; 2064 if (tl->flags & SDTL_OVERLAP) 2065 sd->flags |= SD_OVERLAP; 2066 if (cpumask_equal(cpu_map, sched_domain_span(sd))) 2067 break; 2068 } 2069 } 2070 2071 /* Build the groups for the domains */ 2072 for_each_cpu(i, cpu_map) { 2073 for (sd = *per_cpu_ptr(d.sd, i); sd; sd = sd->parent) { 2074 sd->span_weight = cpumask_weight(sched_domain_span(sd)); 2075 if (sd->flags & SD_OVERLAP) { 2076 if (build_overlap_sched_groups(sd, i)) 2077 goto error; 2078 } else { 2079 if (build_sched_groups(sd, i)) 2080 goto error; 2081 } 2082 } 2083 } 2084 2085 /* Calculate CPU capacity for physical packages and nodes */ 2086 for (i = nr_cpumask_bits-1; i >= 0; i--) { 2087 if (!cpumask_test_cpu(i, cpu_map)) 2088 continue; 2089 2090 for (sd = *per_cpu_ptr(d.sd, i); sd; sd = sd->parent) { 2091 claim_allocations(i, sd); 2092 init_sched_groups_capacity(i, sd); 2093 } 2094 } 2095 2096 /* Attach the domains */ 2097 rcu_read_lock(); 2098 for_each_cpu(i, cpu_map) { 2099 rq = cpu_rq(i); 2100 sd = *per_cpu_ptr(d.sd, i); 2101 2102 /* Use READ_ONCE()/WRITE_ONCE() to avoid load/store tearing: */ 2103 if (rq->cpu_capacity_orig > READ_ONCE(d.rd->max_cpu_capacity)) 2104 WRITE_ONCE(d.rd->max_cpu_capacity, rq->cpu_capacity_orig); 2105 2106 cpu_attach_domain(sd, d.rd, i); 2107 } 2108 rcu_read_unlock(); 2109 2110 if (has_asym) 2111 static_branch_inc_cpuslocked(&sched_asym_cpucapacity); 2112 2113 if (rq && sched_debug_enabled) { 2114 pr_info("root domain span: %*pbl (max cpu_capacity = %lu)\n", 2115 cpumask_pr_args(cpu_map), rq->rd->max_cpu_capacity); 2116 } 2117 2118 ret = 0; 2119 error: 2120 __free_domain_allocs(&d, alloc_state, cpu_map); 2121 2122 return ret; 2123 } 2124 2125 /* Current sched domains: */ 2126 static cpumask_var_t *doms_cur; 2127 2128 /* Number of sched domains in 'doms_cur': */ 2129 static int ndoms_cur; 2130 2131 /* Attribues of custom domains in 'doms_cur' */ 2132 static struct sched_domain_attr *dattr_cur; 2133 2134 /* 2135 * Special case: If a kmalloc() of a doms_cur partition (array of 2136 * cpumask) fails, then fallback to a single sched domain, 2137 * as determined by the single cpumask fallback_doms. 2138 */ 2139 static cpumask_var_t fallback_doms; 2140 2141 /* 2142 * arch_update_cpu_topology lets virtualized architectures update the 2143 * CPU core maps. It is supposed to return 1 if the topology changed 2144 * or 0 if it stayed the same. 2145 */ 2146 int __weak arch_update_cpu_topology(void) 2147 { 2148 return 0; 2149 } 2150 2151 cpumask_var_t *alloc_sched_domains(unsigned int ndoms) 2152 { 2153 int i; 2154 cpumask_var_t *doms; 2155 2156 doms = kmalloc_array(ndoms, sizeof(*doms), GFP_KERNEL); 2157 if (!doms) 2158 return NULL; 2159 for (i = 0; i < ndoms; i++) { 2160 if (!alloc_cpumask_var(&doms[i], GFP_KERNEL)) { 2161 free_sched_domains(doms, i); 2162 return NULL; 2163 } 2164 } 2165 return doms; 2166 } 2167 2168 void free_sched_domains(cpumask_var_t doms[], unsigned int ndoms) 2169 { 2170 unsigned int i; 2171 for (i = 0; i < ndoms; i++) 2172 free_cpumask_var(doms[i]); 2173 kfree(doms); 2174 } 2175 2176 /* 2177 * Set up scheduler domains and groups. For now this just excludes isolated 2178 * CPUs, but could be used to exclude other special cases in the future. 2179 */ 2180 int sched_init_domains(const struct cpumask *cpu_map) 2181 { 2182 int err; 2183 2184 zalloc_cpumask_var(&sched_domains_tmpmask, GFP_KERNEL); 2185 zalloc_cpumask_var(&sched_domains_tmpmask2, GFP_KERNEL); 2186 zalloc_cpumask_var(&fallback_doms, GFP_KERNEL); 2187 2188 arch_update_cpu_topology(); 2189 ndoms_cur = 1; 2190 doms_cur = alloc_sched_domains(ndoms_cur); 2191 if (!doms_cur) 2192 doms_cur = &fallback_doms; 2193 cpumask_and(doms_cur[0], cpu_map, housekeeping_cpumask(HK_FLAG_DOMAIN)); 2194 err = build_sched_domains(doms_cur[0], NULL); 2195 register_sched_domain_sysctl(); 2196 2197 return err; 2198 } 2199 2200 /* 2201 * Detach sched domains from a group of CPUs specified in cpu_map 2202 * These CPUs will now be attached to the NULL domain 2203 */ 2204 static void detach_destroy_domains(const struct cpumask *cpu_map) 2205 { 2206 unsigned int cpu = cpumask_any(cpu_map); 2207 int i; 2208 2209 if (rcu_access_pointer(per_cpu(sd_asym_cpucapacity, cpu))) 2210 static_branch_dec_cpuslocked(&sched_asym_cpucapacity); 2211 2212 rcu_read_lock(); 2213 for_each_cpu(i, cpu_map) 2214 cpu_attach_domain(NULL, &def_root_domain, i); 2215 rcu_read_unlock(); 2216 } 2217 2218 /* handle null as "default" */ 2219 static int dattrs_equal(struct sched_domain_attr *cur, int idx_cur, 2220 struct sched_domain_attr *new, int idx_new) 2221 { 2222 struct sched_domain_attr tmp; 2223 2224 /* Fast path: */ 2225 if (!new && !cur) 2226 return 1; 2227 2228 tmp = SD_ATTR_INIT; 2229 2230 return !memcmp(cur ? (cur + idx_cur) : &tmp, 2231 new ? (new + idx_new) : &tmp, 2232 sizeof(struct sched_domain_attr)); 2233 } 2234 2235 /* 2236 * Partition sched domains as specified by the 'ndoms_new' 2237 * cpumasks in the array doms_new[] of cpumasks. This compares 2238 * doms_new[] to the current sched domain partitioning, doms_cur[]. 2239 * It destroys each deleted domain and builds each new domain. 2240 * 2241 * 'doms_new' is an array of cpumask_var_t's of length 'ndoms_new'. 2242 * The masks don't intersect (don't overlap.) We should setup one 2243 * sched domain for each mask. CPUs not in any of the cpumasks will 2244 * not be load balanced. If the same cpumask appears both in the 2245 * current 'doms_cur' domains and in the new 'doms_new', we can leave 2246 * it as it is. 2247 * 2248 * The passed in 'doms_new' should be allocated using 2249 * alloc_sched_domains. This routine takes ownership of it and will 2250 * free_sched_domains it when done with it. If the caller failed the 2251 * alloc call, then it can pass in doms_new == NULL && ndoms_new == 1, 2252 * and partition_sched_domains() will fallback to the single partition 2253 * 'fallback_doms', it also forces the domains to be rebuilt. 2254 * 2255 * If doms_new == NULL it will be replaced with cpu_online_mask. 2256 * ndoms_new == 0 is a special case for destroying existing domains, 2257 * and it will not create the default domain. 2258 * 2259 * Call with hotplug lock and sched_domains_mutex held 2260 */ 2261 void partition_sched_domains_locked(int ndoms_new, cpumask_var_t doms_new[], 2262 struct sched_domain_attr *dattr_new) 2263 { 2264 bool __maybe_unused has_eas = false; 2265 int i, j, n; 2266 int new_topology; 2267 2268 lockdep_assert_held(&sched_domains_mutex); 2269 2270 /* Always unregister in case we don't destroy any domains: */ 2271 unregister_sched_domain_sysctl(); 2272 2273 /* Let the architecture update CPU core mappings: */ 2274 new_topology = arch_update_cpu_topology(); 2275 2276 if (!doms_new) { 2277 WARN_ON_ONCE(dattr_new); 2278 n = 0; 2279 doms_new = alloc_sched_domains(1); 2280 if (doms_new) { 2281 n = 1; 2282 cpumask_and(doms_new[0], cpu_active_mask, 2283 housekeeping_cpumask(HK_FLAG_DOMAIN)); 2284 } 2285 } else { 2286 n = ndoms_new; 2287 } 2288 2289 /* Destroy deleted domains: */ 2290 for (i = 0; i < ndoms_cur; i++) { 2291 for (j = 0; j < n && !new_topology; j++) { 2292 if (cpumask_equal(doms_cur[i], doms_new[j]) && 2293 dattrs_equal(dattr_cur, i, dattr_new, j)) { 2294 struct root_domain *rd; 2295 2296 /* 2297 * This domain won't be destroyed and as such 2298 * its dl_bw->total_bw needs to be cleared. It 2299 * will be recomputed in function 2300 * update_tasks_root_domain(). 2301 */ 2302 rd = cpu_rq(cpumask_any(doms_cur[i]))->rd; 2303 dl_clear_root_domain(rd); 2304 goto match1; 2305 } 2306 } 2307 /* No match - a current sched domain not in new doms_new[] */ 2308 detach_destroy_domains(doms_cur[i]); 2309 match1: 2310 ; 2311 } 2312 2313 n = ndoms_cur; 2314 if (!doms_new) { 2315 n = 0; 2316 doms_new = &fallback_doms; 2317 cpumask_and(doms_new[0], cpu_active_mask, 2318 housekeeping_cpumask(HK_FLAG_DOMAIN)); 2319 } 2320 2321 /* Build new domains: */ 2322 for (i = 0; i < ndoms_new; i++) { 2323 for (j = 0; j < n && !new_topology; j++) { 2324 if (cpumask_equal(doms_new[i], doms_cur[j]) && 2325 dattrs_equal(dattr_new, i, dattr_cur, j)) 2326 goto match2; 2327 } 2328 /* No match - add a new doms_new */ 2329 build_sched_domains(doms_new[i], dattr_new ? dattr_new + i : NULL); 2330 match2: 2331 ; 2332 } 2333 2334 #if defined(CONFIG_ENERGY_MODEL) && defined(CONFIG_CPU_FREQ_GOV_SCHEDUTIL) 2335 /* Build perf. domains: */ 2336 for (i = 0; i < ndoms_new; i++) { 2337 for (j = 0; j < n && !sched_energy_update; j++) { 2338 if (cpumask_equal(doms_new[i], doms_cur[j]) && 2339 cpu_rq(cpumask_first(doms_cur[j]))->rd->pd) { 2340 has_eas = true; 2341 goto match3; 2342 } 2343 } 2344 /* No match - add perf. domains for a new rd */ 2345 has_eas |= build_perf_domains(doms_new[i]); 2346 match3: 2347 ; 2348 } 2349 sched_energy_set(has_eas); 2350 #endif 2351 2352 /* Remember the new sched domains: */ 2353 if (doms_cur != &fallback_doms) 2354 free_sched_domains(doms_cur, ndoms_cur); 2355 2356 kfree(dattr_cur); 2357 doms_cur = doms_new; 2358 dattr_cur = dattr_new; 2359 ndoms_cur = ndoms_new; 2360 2361 register_sched_domain_sysctl(); 2362 } 2363 2364 /* 2365 * Call with hotplug lock held 2366 */ 2367 void partition_sched_domains(int ndoms_new, cpumask_var_t doms_new[], 2368 struct sched_domain_attr *dattr_new) 2369 { 2370 mutex_lock(&sched_domains_mutex); 2371 partition_sched_domains_locked(ndoms_new, doms_new, dattr_new); 2372 mutex_unlock(&sched_domains_mutex); 2373 } 2374