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_verbose = true; 18 19 return 0; 20 } 21 early_param("sched_verbose", sched_debug_setup); 22 23 static inline bool sched_debug(void) 24 { 25 return sched_debug_verbose; 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_empty(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_verbose) 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_verbose 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_rq_lock_irqsave(rq, 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_rq_unlock_irqrestore(rq, 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 rd->rto_push_work = IRQ_WORK_INIT_HARD(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_FULL); 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; 691 692 /* Remove the sched domains which do not contribute to scheduling. */ 693 for (tmp = sd; tmp; ) { 694 struct sched_domain *parent = tmp->parent; 695 if (!parent) 696 break; 697 698 if (sd_parent_degenerate(tmp, parent)) { 699 tmp->parent = parent->parent; 700 if (parent->parent) 701 parent->parent->child = tmp; 702 /* 703 * Transfer SD_PREFER_SIBLING down in case of a 704 * degenerate parent; the spans match for this 705 * so the property transfers. 706 */ 707 if (parent->flags & SD_PREFER_SIBLING) 708 tmp->flags |= SD_PREFER_SIBLING; 709 destroy_sched_domain(parent); 710 } else 711 tmp = tmp->parent; 712 } 713 714 if (sd && sd_degenerate(sd)) { 715 tmp = sd; 716 sd = sd->parent; 717 destroy_sched_domain(tmp); 718 if (sd) { 719 struct sched_group *sg = sd->groups; 720 721 /* 722 * sched groups hold the flags of the child sched 723 * domain for convenience. Clear such flags since 724 * the child is being destroyed. 725 */ 726 do { 727 sg->flags = 0; 728 } while (sg != sd->groups); 729 730 sd->child = NULL; 731 } 732 } 733 734 sched_domain_debug(sd, cpu); 735 736 rq_attach_root(rq, rd); 737 tmp = rq->sd; 738 rcu_assign_pointer(rq->sd, sd); 739 dirty_sched_domain_sysctl(cpu); 740 destroy_sched_domains(tmp); 741 742 update_top_cache_domain(cpu); 743 } 744 745 struct s_data { 746 struct sched_domain * __percpu *sd; 747 struct root_domain *rd; 748 }; 749 750 enum s_alloc { 751 sa_rootdomain, 752 sa_sd, 753 sa_sd_storage, 754 sa_none, 755 }; 756 757 /* 758 * Return the canonical balance CPU for this group, this is the first CPU 759 * of this group that's also in the balance mask. 760 * 761 * The balance mask are all those CPUs that could actually end up at this 762 * group. See build_balance_mask(). 763 * 764 * Also see should_we_balance(). 765 */ 766 int group_balance_cpu(struct sched_group *sg) 767 { 768 return cpumask_first(group_balance_mask(sg)); 769 } 770 771 772 /* 773 * NUMA topology (first read the regular topology blurb below) 774 * 775 * Given a node-distance table, for example: 776 * 777 * node 0 1 2 3 778 * 0: 10 20 30 20 779 * 1: 20 10 20 30 780 * 2: 30 20 10 20 781 * 3: 20 30 20 10 782 * 783 * which represents a 4 node ring topology like: 784 * 785 * 0 ----- 1 786 * | | 787 * | | 788 * | | 789 * 3 ----- 2 790 * 791 * We want to construct domains and groups to represent this. The way we go 792 * about doing this is to build the domains on 'hops'. For each NUMA level we 793 * construct the mask of all nodes reachable in @level hops. 794 * 795 * For the above NUMA topology that gives 3 levels: 796 * 797 * NUMA-2 0-3 0-3 0-3 0-3 798 * groups: {0-1,3},{1-3} {0-2},{0,2-3} {1-3},{0-1,3} {0,2-3},{0-2} 799 * 800 * NUMA-1 0-1,3 0-2 1-3 0,2-3 801 * groups: {0},{1},{3} {0},{1},{2} {1},{2},{3} {0},{2},{3} 802 * 803 * NUMA-0 0 1 2 3 804 * 805 * 806 * As can be seen; things don't nicely line up as with the regular topology. 807 * When we iterate a domain in child domain chunks some nodes can be 808 * represented multiple times -- hence the "overlap" naming for this part of 809 * the topology. 810 * 811 * In order to minimize this overlap, we only build enough groups to cover the 812 * domain. For instance Node-0 NUMA-2 would only get groups: 0-1,3 and 1-3. 813 * 814 * Because: 815 * 816 * - the first group of each domain is its child domain; this 817 * gets us the first 0-1,3 818 * - the only uncovered node is 2, who's child domain is 1-3. 819 * 820 * However, because of the overlap, computing a unique CPU for each group is 821 * more complicated. Consider for instance the groups of NODE-1 NUMA-2, both 822 * groups include the CPUs of Node-0, while those CPUs would not in fact ever 823 * end up at those groups (they would end up in group: 0-1,3). 824 * 825 * To correct this we have to introduce the group balance mask. This mask 826 * will contain those CPUs in the group that can reach this group given the 827 * (child) domain tree. 828 * 829 * With this we can once again compute balance_cpu and sched_group_capacity 830 * relations. 831 * 832 * XXX include words on how balance_cpu is unique and therefore can be 833 * used for sched_group_capacity links. 834 * 835 * 836 * Another 'interesting' topology is: 837 * 838 * node 0 1 2 3 839 * 0: 10 20 20 30 840 * 1: 20 10 20 20 841 * 2: 20 20 10 20 842 * 3: 30 20 20 10 843 * 844 * Which looks a little like: 845 * 846 * 0 ----- 1 847 * | / | 848 * | / | 849 * | / | 850 * 2 ----- 3 851 * 852 * This topology is asymmetric, nodes 1,2 are fully connected, but nodes 0,3 853 * are not. 854 * 855 * This leads to a few particularly weird cases where the sched_domain's are 856 * not of the same number for each CPU. Consider: 857 * 858 * NUMA-2 0-3 0-3 859 * groups: {0-2},{1-3} {1-3},{0-2} 860 * 861 * NUMA-1 0-2 0-3 0-3 1-3 862 * 863 * NUMA-0 0 1 2 3 864 * 865 */ 866 867 868 /* 869 * Build the balance mask; it contains only those CPUs that can arrive at this 870 * group and should be considered to continue balancing. 871 * 872 * We do this during the group creation pass, therefore the group information 873 * isn't complete yet, however since each group represents a (child) domain we 874 * can fully construct this using the sched_domain bits (which are already 875 * complete). 876 */ 877 static void 878 build_balance_mask(struct sched_domain *sd, struct sched_group *sg, struct cpumask *mask) 879 { 880 const struct cpumask *sg_span = sched_group_span(sg); 881 struct sd_data *sdd = sd->private; 882 struct sched_domain *sibling; 883 int i; 884 885 cpumask_clear(mask); 886 887 for_each_cpu(i, sg_span) { 888 sibling = *per_cpu_ptr(sdd->sd, i); 889 890 /* 891 * Can happen in the asymmetric case, where these siblings are 892 * unused. The mask will not be empty because those CPUs that 893 * do have the top domain _should_ span the domain. 894 */ 895 if (!sibling->child) 896 continue; 897 898 /* If we would not end up here, we can't continue from here */ 899 if (!cpumask_equal(sg_span, sched_domain_span(sibling->child))) 900 continue; 901 902 cpumask_set_cpu(i, mask); 903 } 904 905 /* We must not have empty masks here */ 906 WARN_ON_ONCE(cpumask_empty(mask)); 907 } 908 909 /* 910 * XXX: This creates per-node group entries; since the load-balancer will 911 * immediately access remote memory to construct this group's load-balance 912 * statistics having the groups node local is of dubious benefit. 913 */ 914 static struct sched_group * 915 build_group_from_child_sched_domain(struct sched_domain *sd, int cpu) 916 { 917 struct sched_group *sg; 918 struct cpumask *sg_span; 919 920 sg = kzalloc_node(sizeof(struct sched_group) + cpumask_size(), 921 GFP_KERNEL, cpu_to_node(cpu)); 922 923 if (!sg) 924 return NULL; 925 926 sg_span = sched_group_span(sg); 927 if (sd->child) { 928 cpumask_copy(sg_span, sched_domain_span(sd->child)); 929 sg->flags = sd->child->flags; 930 } else { 931 cpumask_copy(sg_span, sched_domain_span(sd)); 932 } 933 934 atomic_inc(&sg->ref); 935 return sg; 936 } 937 938 static void init_overlap_sched_group(struct sched_domain *sd, 939 struct sched_group *sg) 940 { 941 struct cpumask *mask = sched_domains_tmpmask2; 942 struct sd_data *sdd = sd->private; 943 struct cpumask *sg_span; 944 int cpu; 945 946 build_balance_mask(sd, sg, mask); 947 cpu = cpumask_first(mask); 948 949 sg->sgc = *per_cpu_ptr(sdd->sgc, cpu); 950 if (atomic_inc_return(&sg->sgc->ref) == 1) 951 cpumask_copy(group_balance_mask(sg), mask); 952 else 953 WARN_ON_ONCE(!cpumask_equal(group_balance_mask(sg), mask)); 954 955 /* 956 * Initialize sgc->capacity such that even if we mess up the 957 * domains and no possible iteration will get us here, we won't 958 * die on a /0 trap. 959 */ 960 sg_span = sched_group_span(sg); 961 sg->sgc->capacity = SCHED_CAPACITY_SCALE * cpumask_weight(sg_span); 962 sg->sgc->min_capacity = SCHED_CAPACITY_SCALE; 963 sg->sgc->max_capacity = SCHED_CAPACITY_SCALE; 964 } 965 966 static struct sched_domain * 967 find_descended_sibling(struct sched_domain *sd, struct sched_domain *sibling) 968 { 969 /* 970 * The proper descendant would be the one whose child won't span out 971 * of sd 972 */ 973 while (sibling->child && 974 !cpumask_subset(sched_domain_span(sibling->child), 975 sched_domain_span(sd))) 976 sibling = sibling->child; 977 978 /* 979 * As we are referencing sgc across different topology level, we need 980 * to go down to skip those sched_domains which don't contribute to 981 * scheduling because they will be degenerated in cpu_attach_domain 982 */ 983 while (sibling->child && 984 cpumask_equal(sched_domain_span(sibling->child), 985 sched_domain_span(sibling))) 986 sibling = sibling->child; 987 988 return sibling; 989 } 990 991 static int 992 build_overlap_sched_groups(struct sched_domain *sd, int cpu) 993 { 994 struct sched_group *first = NULL, *last = NULL, *sg; 995 const struct cpumask *span = sched_domain_span(sd); 996 struct cpumask *covered = sched_domains_tmpmask; 997 struct sd_data *sdd = sd->private; 998 struct sched_domain *sibling; 999 int i; 1000 1001 cpumask_clear(covered); 1002 1003 for_each_cpu_wrap(i, span, cpu) { 1004 struct cpumask *sg_span; 1005 1006 if (cpumask_test_cpu(i, covered)) 1007 continue; 1008 1009 sibling = *per_cpu_ptr(sdd->sd, i); 1010 1011 /* 1012 * Asymmetric node setups can result in situations where the 1013 * domain tree is of unequal depth, make sure to skip domains 1014 * that already cover the entire range. 1015 * 1016 * In that case build_sched_domains() will have terminated the 1017 * iteration early and our sibling sd spans will be empty. 1018 * Domains should always include the CPU they're built on, so 1019 * check that. 1020 */ 1021 if (!cpumask_test_cpu(i, sched_domain_span(sibling))) 1022 continue; 1023 1024 /* 1025 * Usually we build sched_group by sibling's child sched_domain 1026 * But for machines whose NUMA diameter are 3 or above, we move 1027 * to build sched_group by sibling's proper descendant's child 1028 * domain because sibling's child sched_domain will span out of 1029 * the sched_domain being built as below. 1030 * 1031 * Smallest diameter=3 topology is: 1032 * 1033 * node 0 1 2 3 1034 * 0: 10 20 30 40 1035 * 1: 20 10 20 30 1036 * 2: 30 20 10 20 1037 * 3: 40 30 20 10 1038 * 1039 * 0 --- 1 --- 2 --- 3 1040 * 1041 * NUMA-3 0-3 N/A N/A 0-3 1042 * groups: {0-2},{1-3} {1-3},{0-2} 1043 * 1044 * NUMA-2 0-2 0-3 0-3 1-3 1045 * groups: {0-1},{1-3} {0-2},{2-3} {1-3},{0-1} {2-3},{0-2} 1046 * 1047 * NUMA-1 0-1 0-2 1-3 2-3 1048 * groups: {0},{1} {1},{2},{0} {2},{3},{1} {3},{2} 1049 * 1050 * NUMA-0 0 1 2 3 1051 * 1052 * The NUMA-2 groups for nodes 0 and 3 are obviously buggered, as the 1053 * group span isn't a subset of the domain span. 1054 */ 1055 if (sibling->child && 1056 !cpumask_subset(sched_domain_span(sibling->child), span)) 1057 sibling = find_descended_sibling(sd, sibling); 1058 1059 sg = build_group_from_child_sched_domain(sibling, cpu); 1060 if (!sg) 1061 goto fail; 1062 1063 sg_span = sched_group_span(sg); 1064 cpumask_or(covered, covered, sg_span); 1065 1066 init_overlap_sched_group(sibling, sg); 1067 1068 if (!first) 1069 first = sg; 1070 if (last) 1071 last->next = sg; 1072 last = sg; 1073 last->next = first; 1074 } 1075 sd->groups = first; 1076 1077 return 0; 1078 1079 fail: 1080 free_sched_groups(first, 0); 1081 1082 return -ENOMEM; 1083 } 1084 1085 1086 /* 1087 * Package topology (also see the load-balance blurb in fair.c) 1088 * 1089 * The scheduler builds a tree structure to represent a number of important 1090 * topology features. By default (default_topology[]) these include: 1091 * 1092 * - Simultaneous multithreading (SMT) 1093 * - Multi-Core Cache (MC) 1094 * - Package (DIE) 1095 * 1096 * Where the last one more or less denotes everything up to a NUMA node. 1097 * 1098 * The tree consists of 3 primary data structures: 1099 * 1100 * sched_domain -> sched_group -> sched_group_capacity 1101 * ^ ^ ^ ^ 1102 * `-' `-' 1103 * 1104 * The sched_domains are per-CPU and have a two way link (parent & child) and 1105 * denote the ever growing mask of CPUs belonging to that level of topology. 1106 * 1107 * Each sched_domain has a circular (double) linked list of sched_group's, each 1108 * denoting the domains of the level below (or individual CPUs in case of the 1109 * first domain level). The sched_group linked by a sched_domain includes the 1110 * CPU of that sched_domain [*]. 1111 * 1112 * Take for instance a 2 threaded, 2 core, 2 cache cluster part: 1113 * 1114 * CPU 0 1 2 3 4 5 6 7 1115 * 1116 * DIE [ ] 1117 * MC [ ] [ ] 1118 * SMT [ ] [ ] [ ] [ ] 1119 * 1120 * - or - 1121 * 1122 * DIE 0-7 0-7 0-7 0-7 0-7 0-7 0-7 0-7 1123 * MC 0-3 0-3 0-3 0-3 4-7 4-7 4-7 4-7 1124 * SMT 0-1 0-1 2-3 2-3 4-5 4-5 6-7 6-7 1125 * 1126 * CPU 0 1 2 3 4 5 6 7 1127 * 1128 * One way to think about it is: sched_domain moves you up and down among these 1129 * topology levels, while sched_group moves you sideways through it, at child 1130 * domain granularity. 1131 * 1132 * sched_group_capacity ensures each unique sched_group has shared storage. 1133 * 1134 * There are two related construction problems, both require a CPU that 1135 * uniquely identify each group (for a given domain): 1136 * 1137 * - The first is the balance_cpu (see should_we_balance() and the 1138 * load-balance blub in fair.c); for each group we only want 1 CPU to 1139 * continue balancing at a higher domain. 1140 * 1141 * - The second is the sched_group_capacity; we want all identical groups 1142 * to share a single sched_group_capacity. 1143 * 1144 * Since these topologies are exclusive by construction. That is, its 1145 * impossible for an SMT thread to belong to multiple cores, and cores to 1146 * be part of multiple caches. There is a very clear and unique location 1147 * for each CPU in the hierarchy. 1148 * 1149 * Therefore computing a unique CPU for each group is trivial (the iteration 1150 * mask is redundant and set all 1s; all CPUs in a group will end up at _that_ 1151 * group), we can simply pick the first CPU in each group. 1152 * 1153 * 1154 * [*] in other words, the first group of each domain is its child domain. 1155 */ 1156 1157 static struct sched_group *get_group(int cpu, struct sd_data *sdd) 1158 { 1159 struct sched_domain *sd = *per_cpu_ptr(sdd->sd, cpu); 1160 struct sched_domain *child = sd->child; 1161 struct sched_group *sg; 1162 bool already_visited; 1163 1164 if (child) 1165 cpu = cpumask_first(sched_domain_span(child)); 1166 1167 sg = *per_cpu_ptr(sdd->sg, cpu); 1168 sg->sgc = *per_cpu_ptr(sdd->sgc, cpu); 1169 1170 /* Increase refcounts for claim_allocations: */ 1171 already_visited = atomic_inc_return(&sg->ref) > 1; 1172 /* sgc visits should follow a similar trend as sg */ 1173 WARN_ON(already_visited != (atomic_inc_return(&sg->sgc->ref) > 1)); 1174 1175 /* If we have already visited that group, it's already initialized. */ 1176 if (already_visited) 1177 return sg; 1178 1179 if (child) { 1180 cpumask_copy(sched_group_span(sg), sched_domain_span(child)); 1181 cpumask_copy(group_balance_mask(sg), sched_group_span(sg)); 1182 sg->flags = child->flags; 1183 } else { 1184 cpumask_set_cpu(cpu, sched_group_span(sg)); 1185 cpumask_set_cpu(cpu, group_balance_mask(sg)); 1186 } 1187 1188 sg->sgc->capacity = SCHED_CAPACITY_SCALE * cpumask_weight(sched_group_span(sg)); 1189 sg->sgc->min_capacity = SCHED_CAPACITY_SCALE; 1190 sg->sgc->max_capacity = SCHED_CAPACITY_SCALE; 1191 1192 return sg; 1193 } 1194 1195 /* 1196 * build_sched_groups will build a circular linked list of the groups 1197 * covered by the given span, will set each group's ->cpumask correctly, 1198 * and will initialize their ->sgc. 1199 * 1200 * Assumes the sched_domain tree is fully constructed 1201 */ 1202 static int 1203 build_sched_groups(struct sched_domain *sd, int cpu) 1204 { 1205 struct sched_group *first = NULL, *last = NULL; 1206 struct sd_data *sdd = sd->private; 1207 const struct cpumask *span = sched_domain_span(sd); 1208 struct cpumask *covered; 1209 int i; 1210 1211 lockdep_assert_held(&sched_domains_mutex); 1212 covered = sched_domains_tmpmask; 1213 1214 cpumask_clear(covered); 1215 1216 for_each_cpu_wrap(i, span, cpu) { 1217 struct sched_group *sg; 1218 1219 if (cpumask_test_cpu(i, covered)) 1220 continue; 1221 1222 sg = get_group(i, sdd); 1223 1224 cpumask_or(covered, covered, sched_group_span(sg)); 1225 1226 if (!first) 1227 first = sg; 1228 if (last) 1229 last->next = sg; 1230 last = sg; 1231 } 1232 last->next = first; 1233 sd->groups = first; 1234 1235 return 0; 1236 } 1237 1238 /* 1239 * Initialize sched groups cpu_capacity. 1240 * 1241 * cpu_capacity indicates the capacity of sched group, which is used while 1242 * distributing the load between different sched groups in a sched domain. 1243 * Typically cpu_capacity for all the groups in a sched domain will be same 1244 * unless there are asymmetries in the topology. If there are asymmetries, 1245 * group having more cpu_capacity will pickup more load compared to the 1246 * group having less cpu_capacity. 1247 */ 1248 static void init_sched_groups_capacity(int cpu, struct sched_domain *sd) 1249 { 1250 struct sched_group *sg = sd->groups; 1251 1252 WARN_ON(!sg); 1253 1254 do { 1255 int cpu, max_cpu = -1; 1256 1257 sg->group_weight = cpumask_weight(sched_group_span(sg)); 1258 1259 if (!(sd->flags & SD_ASYM_PACKING)) 1260 goto next; 1261 1262 for_each_cpu(cpu, sched_group_span(sg)) { 1263 if (max_cpu < 0) 1264 max_cpu = cpu; 1265 else if (sched_asym_prefer(cpu, max_cpu)) 1266 max_cpu = cpu; 1267 } 1268 sg->asym_prefer_cpu = max_cpu; 1269 1270 next: 1271 sg = sg->next; 1272 } while (sg != sd->groups); 1273 1274 if (cpu != group_balance_cpu(sg)) 1275 return; 1276 1277 update_group_capacity(sd, cpu); 1278 } 1279 1280 /* 1281 * Asymmetric CPU capacity bits 1282 */ 1283 struct asym_cap_data { 1284 struct list_head link; 1285 unsigned long capacity; 1286 unsigned long cpus[]; 1287 }; 1288 1289 /* 1290 * Set of available CPUs grouped by their corresponding capacities 1291 * Each list entry contains a CPU mask reflecting CPUs that share the same 1292 * capacity. 1293 * The lifespan of data is unlimited. 1294 */ 1295 static LIST_HEAD(asym_cap_list); 1296 1297 #define cpu_capacity_span(asym_data) to_cpumask((asym_data)->cpus) 1298 1299 /* 1300 * Verify whether there is any CPU capacity asymmetry in a given sched domain. 1301 * Provides sd_flags reflecting the asymmetry scope. 1302 */ 1303 static inline int 1304 asym_cpu_capacity_classify(const struct cpumask *sd_span, 1305 const struct cpumask *cpu_map) 1306 { 1307 struct asym_cap_data *entry; 1308 int count = 0, miss = 0; 1309 1310 /* 1311 * Count how many unique CPU capacities this domain spans across 1312 * (compare sched_domain CPUs mask with ones representing available 1313 * CPUs capacities). Take into account CPUs that might be offline: 1314 * skip those. 1315 */ 1316 list_for_each_entry(entry, &asym_cap_list, link) { 1317 if (cpumask_intersects(sd_span, cpu_capacity_span(entry))) 1318 ++count; 1319 else if (cpumask_intersects(cpu_map, cpu_capacity_span(entry))) 1320 ++miss; 1321 } 1322 1323 WARN_ON_ONCE(!count && !list_empty(&asym_cap_list)); 1324 1325 /* No asymmetry detected */ 1326 if (count < 2) 1327 return 0; 1328 /* Some of the available CPU capacity values have not been detected */ 1329 if (miss) 1330 return SD_ASYM_CPUCAPACITY; 1331 1332 /* Full asymmetry */ 1333 return SD_ASYM_CPUCAPACITY | SD_ASYM_CPUCAPACITY_FULL; 1334 1335 } 1336 1337 static inline void asym_cpu_capacity_update_data(int cpu) 1338 { 1339 unsigned long capacity = arch_scale_cpu_capacity(cpu); 1340 struct asym_cap_data *entry = NULL; 1341 1342 list_for_each_entry(entry, &asym_cap_list, link) { 1343 if (capacity == entry->capacity) 1344 goto done; 1345 } 1346 1347 entry = kzalloc(sizeof(*entry) + cpumask_size(), GFP_KERNEL); 1348 if (WARN_ONCE(!entry, "Failed to allocate memory for asymmetry data\n")) 1349 return; 1350 entry->capacity = capacity; 1351 list_add(&entry->link, &asym_cap_list); 1352 done: 1353 __cpumask_set_cpu(cpu, cpu_capacity_span(entry)); 1354 } 1355 1356 /* 1357 * Build-up/update list of CPUs grouped by their capacities 1358 * An update requires explicit request to rebuild sched domains 1359 * with state indicating CPU topology changes. 1360 */ 1361 static void asym_cpu_capacity_scan(void) 1362 { 1363 struct asym_cap_data *entry, *next; 1364 int cpu; 1365 1366 list_for_each_entry(entry, &asym_cap_list, link) 1367 cpumask_clear(cpu_capacity_span(entry)); 1368 1369 for_each_cpu_and(cpu, cpu_possible_mask, housekeeping_cpumask(HK_TYPE_DOMAIN)) 1370 asym_cpu_capacity_update_data(cpu); 1371 1372 list_for_each_entry_safe(entry, next, &asym_cap_list, link) { 1373 if (cpumask_empty(cpu_capacity_span(entry))) { 1374 list_del(&entry->link); 1375 kfree(entry); 1376 } 1377 } 1378 1379 /* 1380 * Only one capacity value has been detected i.e. this system is symmetric. 1381 * No need to keep this data around. 1382 */ 1383 if (list_is_singular(&asym_cap_list)) { 1384 entry = list_first_entry(&asym_cap_list, typeof(*entry), link); 1385 list_del(&entry->link); 1386 kfree(entry); 1387 } 1388 } 1389 1390 /* 1391 * Initializers for schedule domains 1392 * Non-inlined to reduce accumulated stack pressure in build_sched_domains() 1393 */ 1394 1395 static int default_relax_domain_level = -1; 1396 int sched_domain_level_max; 1397 1398 static int __init setup_relax_domain_level(char *str) 1399 { 1400 if (kstrtoint(str, 0, &default_relax_domain_level)) 1401 pr_warn("Unable to set relax_domain_level\n"); 1402 1403 return 1; 1404 } 1405 __setup("relax_domain_level=", setup_relax_domain_level); 1406 1407 static void set_domain_attribute(struct sched_domain *sd, 1408 struct sched_domain_attr *attr) 1409 { 1410 int request; 1411 1412 if (!attr || attr->relax_domain_level < 0) { 1413 if (default_relax_domain_level < 0) 1414 return; 1415 request = default_relax_domain_level; 1416 } else 1417 request = attr->relax_domain_level; 1418 1419 if (sd->level > request) { 1420 /* Turn off idle balance on this domain: */ 1421 sd->flags &= ~(SD_BALANCE_WAKE|SD_BALANCE_NEWIDLE); 1422 } 1423 } 1424 1425 static void __sdt_free(const struct cpumask *cpu_map); 1426 static int __sdt_alloc(const struct cpumask *cpu_map); 1427 1428 static void __free_domain_allocs(struct s_data *d, enum s_alloc what, 1429 const struct cpumask *cpu_map) 1430 { 1431 switch (what) { 1432 case sa_rootdomain: 1433 if (!atomic_read(&d->rd->refcount)) 1434 free_rootdomain(&d->rd->rcu); 1435 fallthrough; 1436 case sa_sd: 1437 free_percpu(d->sd); 1438 fallthrough; 1439 case sa_sd_storage: 1440 __sdt_free(cpu_map); 1441 fallthrough; 1442 case sa_none: 1443 break; 1444 } 1445 } 1446 1447 static enum s_alloc 1448 __visit_domain_allocation_hell(struct s_data *d, const struct cpumask *cpu_map) 1449 { 1450 memset(d, 0, sizeof(*d)); 1451 1452 if (__sdt_alloc(cpu_map)) 1453 return sa_sd_storage; 1454 d->sd = alloc_percpu(struct sched_domain *); 1455 if (!d->sd) 1456 return sa_sd_storage; 1457 d->rd = alloc_rootdomain(); 1458 if (!d->rd) 1459 return sa_sd; 1460 1461 return sa_rootdomain; 1462 } 1463 1464 /* 1465 * NULL the sd_data elements we've used to build the sched_domain and 1466 * sched_group structure so that the subsequent __free_domain_allocs() 1467 * will not free the data we're using. 1468 */ 1469 static void claim_allocations(int cpu, struct sched_domain *sd) 1470 { 1471 struct sd_data *sdd = sd->private; 1472 1473 WARN_ON_ONCE(*per_cpu_ptr(sdd->sd, cpu) != sd); 1474 *per_cpu_ptr(sdd->sd, cpu) = NULL; 1475 1476 if (atomic_read(&(*per_cpu_ptr(sdd->sds, cpu))->ref)) 1477 *per_cpu_ptr(sdd->sds, cpu) = NULL; 1478 1479 if (atomic_read(&(*per_cpu_ptr(sdd->sg, cpu))->ref)) 1480 *per_cpu_ptr(sdd->sg, cpu) = NULL; 1481 1482 if (atomic_read(&(*per_cpu_ptr(sdd->sgc, cpu))->ref)) 1483 *per_cpu_ptr(sdd->sgc, cpu) = NULL; 1484 } 1485 1486 #ifdef CONFIG_NUMA 1487 enum numa_topology_type sched_numa_topology_type; 1488 1489 static int sched_domains_numa_levels; 1490 static int sched_domains_curr_level; 1491 1492 int sched_max_numa_distance; 1493 static int *sched_domains_numa_distance; 1494 static struct cpumask ***sched_domains_numa_masks; 1495 #endif 1496 1497 /* 1498 * SD_flags allowed in topology descriptions. 1499 * 1500 * These flags are purely descriptive of the topology and do not prescribe 1501 * behaviour. Behaviour is artificial and mapped in the below sd_init() 1502 * function: 1503 * 1504 * SD_SHARE_CPUCAPACITY - describes SMT topologies 1505 * SD_SHARE_PKG_RESOURCES - describes shared caches 1506 * SD_NUMA - describes NUMA topologies 1507 * 1508 * Odd one out, which beside describing the topology has a quirk also 1509 * prescribes the desired behaviour that goes along with it: 1510 * 1511 * SD_ASYM_PACKING - describes SMT quirks 1512 */ 1513 #define TOPOLOGY_SD_FLAGS \ 1514 (SD_SHARE_CPUCAPACITY | \ 1515 SD_SHARE_PKG_RESOURCES | \ 1516 SD_NUMA | \ 1517 SD_ASYM_PACKING) 1518 1519 static struct sched_domain * 1520 sd_init(struct sched_domain_topology_level *tl, 1521 const struct cpumask *cpu_map, 1522 struct sched_domain *child, int cpu) 1523 { 1524 struct sd_data *sdd = &tl->data; 1525 struct sched_domain *sd = *per_cpu_ptr(sdd->sd, cpu); 1526 int sd_id, sd_weight, sd_flags = 0; 1527 struct cpumask *sd_span; 1528 1529 #ifdef CONFIG_NUMA 1530 /* 1531 * Ugly hack to pass state to sd_numa_mask()... 1532 */ 1533 sched_domains_curr_level = tl->numa_level; 1534 #endif 1535 1536 sd_weight = cpumask_weight(tl->mask(cpu)); 1537 1538 if (tl->sd_flags) 1539 sd_flags = (*tl->sd_flags)(); 1540 if (WARN_ONCE(sd_flags & ~TOPOLOGY_SD_FLAGS, 1541 "wrong sd_flags in topology description\n")) 1542 sd_flags &= TOPOLOGY_SD_FLAGS; 1543 1544 *sd = (struct sched_domain){ 1545 .min_interval = sd_weight, 1546 .max_interval = 2*sd_weight, 1547 .busy_factor = 16, 1548 .imbalance_pct = 117, 1549 1550 .cache_nice_tries = 0, 1551 1552 .flags = 1*SD_BALANCE_NEWIDLE 1553 | 1*SD_BALANCE_EXEC 1554 | 1*SD_BALANCE_FORK 1555 | 0*SD_BALANCE_WAKE 1556 | 1*SD_WAKE_AFFINE 1557 | 0*SD_SHARE_CPUCAPACITY 1558 | 0*SD_SHARE_PKG_RESOURCES 1559 | 0*SD_SERIALIZE 1560 | 1*SD_PREFER_SIBLING 1561 | 0*SD_NUMA 1562 | sd_flags 1563 , 1564 1565 .last_balance = jiffies, 1566 .balance_interval = sd_weight, 1567 .max_newidle_lb_cost = 0, 1568 .last_decay_max_lb_cost = jiffies, 1569 .child = child, 1570 #ifdef CONFIG_SCHED_DEBUG 1571 .name = tl->name, 1572 #endif 1573 }; 1574 1575 sd_span = sched_domain_span(sd); 1576 cpumask_and(sd_span, cpu_map, tl->mask(cpu)); 1577 sd_id = cpumask_first(sd_span); 1578 1579 sd->flags |= asym_cpu_capacity_classify(sd_span, cpu_map); 1580 1581 WARN_ONCE((sd->flags & (SD_SHARE_CPUCAPACITY | SD_ASYM_CPUCAPACITY)) == 1582 (SD_SHARE_CPUCAPACITY | SD_ASYM_CPUCAPACITY), 1583 "CPU capacity asymmetry not supported on SMT\n"); 1584 1585 /* 1586 * Convert topological properties into behaviour. 1587 */ 1588 /* Don't attempt to spread across CPUs of different capacities. */ 1589 if ((sd->flags & SD_ASYM_CPUCAPACITY) && sd->child) 1590 sd->child->flags &= ~SD_PREFER_SIBLING; 1591 1592 if (sd->flags & SD_SHARE_CPUCAPACITY) { 1593 sd->imbalance_pct = 110; 1594 1595 } else if (sd->flags & SD_SHARE_PKG_RESOURCES) { 1596 sd->imbalance_pct = 117; 1597 sd->cache_nice_tries = 1; 1598 1599 #ifdef CONFIG_NUMA 1600 } else if (sd->flags & SD_NUMA) { 1601 sd->cache_nice_tries = 2; 1602 1603 sd->flags &= ~SD_PREFER_SIBLING; 1604 sd->flags |= SD_SERIALIZE; 1605 if (sched_domains_numa_distance[tl->numa_level] > node_reclaim_distance) { 1606 sd->flags &= ~(SD_BALANCE_EXEC | 1607 SD_BALANCE_FORK | 1608 SD_WAKE_AFFINE); 1609 } 1610 1611 #endif 1612 } else { 1613 sd->cache_nice_tries = 1; 1614 } 1615 1616 /* 1617 * For all levels sharing cache; connect a sched_domain_shared 1618 * instance. 1619 */ 1620 if (sd->flags & SD_SHARE_PKG_RESOURCES) { 1621 sd->shared = *per_cpu_ptr(sdd->sds, sd_id); 1622 atomic_inc(&sd->shared->ref); 1623 atomic_set(&sd->shared->nr_busy_cpus, sd_weight); 1624 } 1625 1626 sd->private = sdd; 1627 1628 return sd; 1629 } 1630 1631 /* 1632 * Topology list, bottom-up. 1633 */ 1634 static struct sched_domain_topology_level default_topology[] = { 1635 #ifdef CONFIG_SCHED_SMT 1636 { cpu_smt_mask, cpu_smt_flags, SD_INIT_NAME(SMT) }, 1637 #endif 1638 1639 #ifdef CONFIG_SCHED_CLUSTER 1640 { cpu_clustergroup_mask, cpu_cluster_flags, SD_INIT_NAME(CLS) }, 1641 #endif 1642 1643 #ifdef CONFIG_SCHED_MC 1644 { cpu_coregroup_mask, cpu_core_flags, SD_INIT_NAME(MC) }, 1645 #endif 1646 { cpu_cpu_mask, SD_INIT_NAME(DIE) }, 1647 { NULL, }, 1648 }; 1649 1650 static struct sched_domain_topology_level *sched_domain_topology = 1651 default_topology; 1652 static struct sched_domain_topology_level *sched_domain_topology_saved; 1653 1654 #define for_each_sd_topology(tl) \ 1655 for (tl = sched_domain_topology; tl->mask; tl++) 1656 1657 void set_sched_topology(struct sched_domain_topology_level *tl) 1658 { 1659 if (WARN_ON_ONCE(sched_smp_initialized)) 1660 return; 1661 1662 sched_domain_topology = tl; 1663 sched_domain_topology_saved = NULL; 1664 } 1665 1666 #ifdef CONFIG_NUMA 1667 1668 static const struct cpumask *sd_numa_mask(int cpu) 1669 { 1670 return sched_domains_numa_masks[sched_domains_curr_level][cpu_to_node(cpu)]; 1671 } 1672 1673 static void sched_numa_warn(const char *str) 1674 { 1675 static int done = false; 1676 int i,j; 1677 1678 if (done) 1679 return; 1680 1681 done = true; 1682 1683 printk(KERN_WARNING "ERROR: %s\n\n", str); 1684 1685 for (i = 0; i < nr_node_ids; i++) { 1686 printk(KERN_WARNING " "); 1687 for (j = 0; j < nr_node_ids; j++) { 1688 if (!node_state(i, N_CPU) || !node_state(j, N_CPU)) 1689 printk(KERN_CONT "(%02d) ", node_distance(i,j)); 1690 else 1691 printk(KERN_CONT " %02d ", node_distance(i,j)); 1692 } 1693 printk(KERN_CONT "\n"); 1694 } 1695 printk(KERN_WARNING "\n"); 1696 } 1697 1698 bool find_numa_distance(int distance) 1699 { 1700 bool found = false; 1701 int i, *distances; 1702 1703 if (distance == node_distance(0, 0)) 1704 return true; 1705 1706 rcu_read_lock(); 1707 distances = rcu_dereference(sched_domains_numa_distance); 1708 if (!distances) 1709 goto unlock; 1710 for (i = 0; i < sched_domains_numa_levels; i++) { 1711 if (distances[i] == distance) { 1712 found = true; 1713 break; 1714 } 1715 } 1716 unlock: 1717 rcu_read_unlock(); 1718 1719 return found; 1720 } 1721 1722 #define for_each_cpu_node_but(n, nbut) \ 1723 for_each_node_state(n, N_CPU) \ 1724 if (n == nbut) \ 1725 continue; \ 1726 else 1727 1728 /* 1729 * A system can have three types of NUMA topology: 1730 * NUMA_DIRECT: all nodes are directly connected, or not a NUMA system 1731 * NUMA_GLUELESS_MESH: some nodes reachable through intermediary nodes 1732 * NUMA_BACKPLANE: nodes can reach other nodes through a backplane 1733 * 1734 * The difference between a glueless mesh topology and a backplane 1735 * topology lies in whether communication between not directly 1736 * connected nodes goes through intermediary nodes (where programs 1737 * could run), or through backplane controllers. This affects 1738 * placement of programs. 1739 * 1740 * The type of topology can be discerned with the following tests: 1741 * - If the maximum distance between any nodes is 1 hop, the system 1742 * is directly connected. 1743 * - If for two nodes A and B, located N > 1 hops away from each other, 1744 * there is an intermediary node C, which is < N hops away from both 1745 * nodes A and B, the system is a glueless mesh. 1746 */ 1747 static void init_numa_topology_type(int offline_node) 1748 { 1749 int a, b, c, n; 1750 1751 n = sched_max_numa_distance; 1752 1753 if (sched_domains_numa_levels <= 2) { 1754 sched_numa_topology_type = NUMA_DIRECT; 1755 return; 1756 } 1757 1758 for_each_cpu_node_but(a, offline_node) { 1759 for_each_cpu_node_but(b, offline_node) { 1760 /* Find two nodes furthest removed from each other. */ 1761 if (node_distance(a, b) < n) 1762 continue; 1763 1764 /* Is there an intermediary node between a and b? */ 1765 for_each_cpu_node_but(c, offline_node) { 1766 if (node_distance(a, c) < n && 1767 node_distance(b, c) < n) { 1768 sched_numa_topology_type = 1769 NUMA_GLUELESS_MESH; 1770 return; 1771 } 1772 } 1773 1774 sched_numa_topology_type = NUMA_BACKPLANE; 1775 return; 1776 } 1777 } 1778 1779 pr_err("Failed to find a NUMA topology type, defaulting to DIRECT\n"); 1780 sched_numa_topology_type = NUMA_DIRECT; 1781 } 1782 1783 1784 #define NR_DISTANCE_VALUES (1 << DISTANCE_BITS) 1785 1786 void sched_init_numa(int offline_node) 1787 { 1788 struct sched_domain_topology_level *tl; 1789 unsigned long *distance_map; 1790 int nr_levels = 0; 1791 int i, j; 1792 int *distances; 1793 struct cpumask ***masks; 1794 1795 /* 1796 * O(nr_nodes^2) deduplicating selection sort -- in order to find the 1797 * unique distances in the node_distance() table. 1798 */ 1799 distance_map = bitmap_alloc(NR_DISTANCE_VALUES, GFP_KERNEL); 1800 if (!distance_map) 1801 return; 1802 1803 bitmap_zero(distance_map, NR_DISTANCE_VALUES); 1804 for_each_cpu_node_but(i, offline_node) { 1805 for_each_cpu_node_but(j, offline_node) { 1806 int distance = node_distance(i, j); 1807 1808 if (distance < LOCAL_DISTANCE || distance >= NR_DISTANCE_VALUES) { 1809 sched_numa_warn("Invalid distance value range"); 1810 bitmap_free(distance_map); 1811 return; 1812 } 1813 1814 bitmap_set(distance_map, distance, 1); 1815 } 1816 } 1817 /* 1818 * We can now figure out how many unique distance values there are and 1819 * allocate memory accordingly. 1820 */ 1821 nr_levels = bitmap_weight(distance_map, NR_DISTANCE_VALUES); 1822 1823 distances = kcalloc(nr_levels, sizeof(int), GFP_KERNEL); 1824 if (!distances) { 1825 bitmap_free(distance_map); 1826 return; 1827 } 1828 1829 for (i = 0, j = 0; i < nr_levels; i++, j++) { 1830 j = find_next_bit(distance_map, NR_DISTANCE_VALUES, j); 1831 distances[i] = j; 1832 } 1833 rcu_assign_pointer(sched_domains_numa_distance, distances); 1834 1835 bitmap_free(distance_map); 1836 1837 /* 1838 * 'nr_levels' contains the number of unique distances 1839 * 1840 * The sched_domains_numa_distance[] array includes the actual distance 1841 * numbers. 1842 */ 1843 1844 /* 1845 * Here, we should temporarily reset sched_domains_numa_levels to 0. 1846 * If it fails to allocate memory for array sched_domains_numa_masks[][], 1847 * the array will contain less then 'nr_levels' members. This could be 1848 * dangerous when we use it to iterate array sched_domains_numa_masks[][] 1849 * in other functions. 1850 * 1851 * We reset it to 'nr_levels' at the end of this function. 1852 */ 1853 sched_domains_numa_levels = 0; 1854 1855 masks = kzalloc(sizeof(void *) * nr_levels, GFP_KERNEL); 1856 if (!masks) 1857 return; 1858 1859 /* 1860 * Now for each level, construct a mask per node which contains all 1861 * CPUs of nodes that are that many hops away from us. 1862 */ 1863 for (i = 0; i < nr_levels; i++) { 1864 masks[i] = kzalloc(nr_node_ids * sizeof(void *), GFP_KERNEL); 1865 if (!masks[i]) 1866 return; 1867 1868 for_each_cpu_node_but(j, offline_node) { 1869 struct cpumask *mask = kzalloc(cpumask_size(), GFP_KERNEL); 1870 int k; 1871 1872 if (!mask) 1873 return; 1874 1875 masks[i][j] = mask; 1876 1877 for_each_cpu_node_but(k, offline_node) { 1878 if (sched_debug() && (node_distance(j, k) != node_distance(k, j))) 1879 sched_numa_warn("Node-distance not symmetric"); 1880 1881 if (node_distance(j, k) > sched_domains_numa_distance[i]) 1882 continue; 1883 1884 cpumask_or(mask, mask, cpumask_of_node(k)); 1885 } 1886 } 1887 } 1888 rcu_assign_pointer(sched_domains_numa_masks, masks); 1889 1890 /* Compute default topology size */ 1891 for (i = 0; sched_domain_topology[i].mask; i++); 1892 1893 tl = kzalloc((i + nr_levels + 1) * 1894 sizeof(struct sched_domain_topology_level), GFP_KERNEL); 1895 if (!tl) 1896 return; 1897 1898 /* 1899 * Copy the default topology bits.. 1900 */ 1901 for (i = 0; sched_domain_topology[i].mask; i++) 1902 tl[i] = sched_domain_topology[i]; 1903 1904 /* 1905 * Add the NUMA identity distance, aka single NODE. 1906 */ 1907 tl[i++] = (struct sched_domain_topology_level){ 1908 .mask = sd_numa_mask, 1909 .numa_level = 0, 1910 SD_INIT_NAME(NODE) 1911 }; 1912 1913 /* 1914 * .. and append 'j' levels of NUMA goodness. 1915 */ 1916 for (j = 1; j < nr_levels; i++, j++) { 1917 tl[i] = (struct sched_domain_topology_level){ 1918 .mask = sd_numa_mask, 1919 .sd_flags = cpu_numa_flags, 1920 .flags = SDTL_OVERLAP, 1921 .numa_level = j, 1922 SD_INIT_NAME(NUMA) 1923 }; 1924 } 1925 1926 sched_domain_topology_saved = sched_domain_topology; 1927 sched_domain_topology = tl; 1928 1929 sched_domains_numa_levels = nr_levels; 1930 WRITE_ONCE(sched_max_numa_distance, sched_domains_numa_distance[nr_levels - 1]); 1931 1932 init_numa_topology_type(offline_node); 1933 } 1934 1935 1936 static void sched_reset_numa(void) 1937 { 1938 int nr_levels, *distances; 1939 struct cpumask ***masks; 1940 1941 nr_levels = sched_domains_numa_levels; 1942 sched_domains_numa_levels = 0; 1943 sched_max_numa_distance = 0; 1944 sched_numa_topology_type = NUMA_DIRECT; 1945 distances = sched_domains_numa_distance; 1946 rcu_assign_pointer(sched_domains_numa_distance, NULL); 1947 masks = sched_domains_numa_masks; 1948 rcu_assign_pointer(sched_domains_numa_masks, NULL); 1949 if (distances || masks) { 1950 int i, j; 1951 1952 synchronize_rcu(); 1953 kfree(distances); 1954 for (i = 0; i < nr_levels && masks; i++) { 1955 if (!masks[i]) 1956 continue; 1957 for_each_node(j) 1958 kfree(masks[i][j]); 1959 kfree(masks[i]); 1960 } 1961 kfree(masks); 1962 } 1963 if (sched_domain_topology_saved) { 1964 kfree(sched_domain_topology); 1965 sched_domain_topology = sched_domain_topology_saved; 1966 sched_domain_topology_saved = NULL; 1967 } 1968 } 1969 1970 /* 1971 * Call with hotplug lock held 1972 */ 1973 void sched_update_numa(int cpu, bool online) 1974 { 1975 int node; 1976 1977 node = cpu_to_node(cpu); 1978 /* 1979 * Scheduler NUMA topology is updated when the first CPU of a 1980 * node is onlined or the last CPU of a node is offlined. 1981 */ 1982 if (cpumask_weight(cpumask_of_node(node)) != 1) 1983 return; 1984 1985 sched_reset_numa(); 1986 sched_init_numa(online ? NUMA_NO_NODE : node); 1987 } 1988 1989 void sched_domains_numa_masks_set(unsigned int cpu) 1990 { 1991 int node = cpu_to_node(cpu); 1992 int i, j; 1993 1994 for (i = 0; i < sched_domains_numa_levels; i++) { 1995 for (j = 0; j < nr_node_ids; j++) { 1996 if (!node_state(j, N_CPU)) 1997 continue; 1998 1999 /* Set ourselves in the remote node's masks */ 2000 if (node_distance(j, node) <= sched_domains_numa_distance[i]) 2001 cpumask_set_cpu(cpu, sched_domains_numa_masks[i][j]); 2002 } 2003 } 2004 } 2005 2006 void sched_domains_numa_masks_clear(unsigned int cpu) 2007 { 2008 int i, j; 2009 2010 for (i = 0; i < sched_domains_numa_levels; i++) { 2011 for (j = 0; j < nr_node_ids; j++) { 2012 if (sched_domains_numa_masks[i][j]) 2013 cpumask_clear_cpu(cpu, sched_domains_numa_masks[i][j]); 2014 } 2015 } 2016 } 2017 2018 /* 2019 * sched_numa_find_closest() - given the NUMA topology, find the cpu 2020 * closest to @cpu from @cpumask. 2021 * cpumask: cpumask to find a cpu from 2022 * cpu: cpu to be close to 2023 * 2024 * returns: cpu, or nr_cpu_ids when nothing found. 2025 */ 2026 int sched_numa_find_closest(const struct cpumask *cpus, int cpu) 2027 { 2028 int i, j = cpu_to_node(cpu), found = nr_cpu_ids; 2029 struct cpumask ***masks; 2030 2031 rcu_read_lock(); 2032 masks = rcu_dereference(sched_domains_numa_masks); 2033 if (!masks) 2034 goto unlock; 2035 for (i = 0; i < sched_domains_numa_levels; i++) { 2036 if (!masks[i][j]) 2037 break; 2038 cpu = cpumask_any_and(cpus, masks[i][j]); 2039 if (cpu < nr_cpu_ids) { 2040 found = cpu; 2041 break; 2042 } 2043 } 2044 unlock: 2045 rcu_read_unlock(); 2046 2047 return found; 2048 } 2049 2050 #endif /* CONFIG_NUMA */ 2051 2052 static int __sdt_alloc(const struct cpumask *cpu_map) 2053 { 2054 struct sched_domain_topology_level *tl; 2055 int j; 2056 2057 for_each_sd_topology(tl) { 2058 struct sd_data *sdd = &tl->data; 2059 2060 sdd->sd = alloc_percpu(struct sched_domain *); 2061 if (!sdd->sd) 2062 return -ENOMEM; 2063 2064 sdd->sds = alloc_percpu(struct sched_domain_shared *); 2065 if (!sdd->sds) 2066 return -ENOMEM; 2067 2068 sdd->sg = alloc_percpu(struct sched_group *); 2069 if (!sdd->sg) 2070 return -ENOMEM; 2071 2072 sdd->sgc = alloc_percpu(struct sched_group_capacity *); 2073 if (!sdd->sgc) 2074 return -ENOMEM; 2075 2076 for_each_cpu(j, cpu_map) { 2077 struct sched_domain *sd; 2078 struct sched_domain_shared *sds; 2079 struct sched_group *sg; 2080 struct sched_group_capacity *sgc; 2081 2082 sd = kzalloc_node(sizeof(struct sched_domain) + cpumask_size(), 2083 GFP_KERNEL, cpu_to_node(j)); 2084 if (!sd) 2085 return -ENOMEM; 2086 2087 *per_cpu_ptr(sdd->sd, j) = sd; 2088 2089 sds = kzalloc_node(sizeof(struct sched_domain_shared), 2090 GFP_KERNEL, cpu_to_node(j)); 2091 if (!sds) 2092 return -ENOMEM; 2093 2094 *per_cpu_ptr(sdd->sds, j) = sds; 2095 2096 sg = kzalloc_node(sizeof(struct sched_group) + cpumask_size(), 2097 GFP_KERNEL, cpu_to_node(j)); 2098 if (!sg) 2099 return -ENOMEM; 2100 2101 sg->next = sg; 2102 2103 *per_cpu_ptr(sdd->sg, j) = sg; 2104 2105 sgc = kzalloc_node(sizeof(struct sched_group_capacity) + cpumask_size(), 2106 GFP_KERNEL, cpu_to_node(j)); 2107 if (!sgc) 2108 return -ENOMEM; 2109 2110 #ifdef CONFIG_SCHED_DEBUG 2111 sgc->id = j; 2112 #endif 2113 2114 *per_cpu_ptr(sdd->sgc, j) = sgc; 2115 } 2116 } 2117 2118 return 0; 2119 } 2120 2121 static void __sdt_free(const struct cpumask *cpu_map) 2122 { 2123 struct sched_domain_topology_level *tl; 2124 int j; 2125 2126 for_each_sd_topology(tl) { 2127 struct sd_data *sdd = &tl->data; 2128 2129 for_each_cpu(j, cpu_map) { 2130 struct sched_domain *sd; 2131 2132 if (sdd->sd) { 2133 sd = *per_cpu_ptr(sdd->sd, j); 2134 if (sd && (sd->flags & SD_OVERLAP)) 2135 free_sched_groups(sd->groups, 0); 2136 kfree(*per_cpu_ptr(sdd->sd, j)); 2137 } 2138 2139 if (sdd->sds) 2140 kfree(*per_cpu_ptr(sdd->sds, j)); 2141 if (sdd->sg) 2142 kfree(*per_cpu_ptr(sdd->sg, j)); 2143 if (sdd->sgc) 2144 kfree(*per_cpu_ptr(sdd->sgc, j)); 2145 } 2146 free_percpu(sdd->sd); 2147 sdd->sd = NULL; 2148 free_percpu(sdd->sds); 2149 sdd->sds = NULL; 2150 free_percpu(sdd->sg); 2151 sdd->sg = NULL; 2152 free_percpu(sdd->sgc); 2153 sdd->sgc = NULL; 2154 } 2155 } 2156 2157 static struct sched_domain *build_sched_domain(struct sched_domain_topology_level *tl, 2158 const struct cpumask *cpu_map, struct sched_domain_attr *attr, 2159 struct sched_domain *child, int cpu) 2160 { 2161 struct sched_domain *sd = sd_init(tl, cpu_map, child, cpu); 2162 2163 if (child) { 2164 sd->level = child->level + 1; 2165 sched_domain_level_max = max(sched_domain_level_max, sd->level); 2166 child->parent = sd; 2167 2168 if (!cpumask_subset(sched_domain_span(child), 2169 sched_domain_span(sd))) { 2170 pr_err("BUG: arch topology borken\n"); 2171 #ifdef CONFIG_SCHED_DEBUG 2172 pr_err(" the %s domain not a subset of the %s domain\n", 2173 child->name, sd->name); 2174 #endif 2175 /* Fixup, ensure @sd has at least @child CPUs. */ 2176 cpumask_or(sched_domain_span(sd), 2177 sched_domain_span(sd), 2178 sched_domain_span(child)); 2179 } 2180 2181 } 2182 set_domain_attribute(sd, attr); 2183 2184 return sd; 2185 } 2186 2187 /* 2188 * Ensure topology masks are sane, i.e. there are no conflicts (overlaps) for 2189 * any two given CPUs at this (non-NUMA) topology level. 2190 */ 2191 static bool topology_span_sane(struct sched_domain_topology_level *tl, 2192 const struct cpumask *cpu_map, int cpu) 2193 { 2194 int i; 2195 2196 /* NUMA levels are allowed to overlap */ 2197 if (tl->flags & SDTL_OVERLAP) 2198 return true; 2199 2200 /* 2201 * Non-NUMA levels cannot partially overlap - they must be either 2202 * completely equal or completely disjoint. Otherwise we can end up 2203 * breaking the sched_group lists - i.e. a later get_group() pass 2204 * breaks the linking done for an earlier span. 2205 */ 2206 for_each_cpu(i, cpu_map) { 2207 if (i == cpu) 2208 continue; 2209 /* 2210 * We should 'and' all those masks with 'cpu_map' to exactly 2211 * match the topology we're about to build, but that can only 2212 * remove CPUs, which only lessens our ability to detect 2213 * overlaps 2214 */ 2215 if (!cpumask_equal(tl->mask(cpu), tl->mask(i)) && 2216 cpumask_intersects(tl->mask(cpu), tl->mask(i))) 2217 return false; 2218 } 2219 2220 return true; 2221 } 2222 2223 /* 2224 * Build sched domains for a given set of CPUs and attach the sched domains 2225 * to the individual CPUs 2226 */ 2227 static int 2228 build_sched_domains(const struct cpumask *cpu_map, struct sched_domain_attr *attr) 2229 { 2230 enum s_alloc alloc_state = sa_none; 2231 struct sched_domain *sd; 2232 struct s_data d; 2233 struct rq *rq = NULL; 2234 int i, ret = -ENOMEM; 2235 bool has_asym = false; 2236 2237 if (WARN_ON(cpumask_empty(cpu_map))) 2238 goto error; 2239 2240 alloc_state = __visit_domain_allocation_hell(&d, cpu_map); 2241 if (alloc_state != sa_rootdomain) 2242 goto error; 2243 2244 /* Set up domains for CPUs specified by the cpu_map: */ 2245 for_each_cpu(i, cpu_map) { 2246 struct sched_domain_topology_level *tl; 2247 2248 sd = NULL; 2249 for_each_sd_topology(tl) { 2250 2251 if (WARN_ON(!topology_span_sane(tl, cpu_map, i))) 2252 goto error; 2253 2254 sd = build_sched_domain(tl, cpu_map, attr, sd, i); 2255 2256 has_asym |= sd->flags & SD_ASYM_CPUCAPACITY; 2257 2258 if (tl == sched_domain_topology) 2259 *per_cpu_ptr(d.sd, i) = sd; 2260 if (tl->flags & SDTL_OVERLAP) 2261 sd->flags |= SD_OVERLAP; 2262 if (cpumask_equal(cpu_map, sched_domain_span(sd))) 2263 break; 2264 } 2265 } 2266 2267 /* Build the groups for the domains */ 2268 for_each_cpu(i, cpu_map) { 2269 for (sd = *per_cpu_ptr(d.sd, i); sd; sd = sd->parent) { 2270 sd->span_weight = cpumask_weight(sched_domain_span(sd)); 2271 if (sd->flags & SD_OVERLAP) { 2272 if (build_overlap_sched_groups(sd, i)) 2273 goto error; 2274 } else { 2275 if (build_sched_groups(sd, i)) 2276 goto error; 2277 } 2278 } 2279 } 2280 2281 /* 2282 * Calculate an allowed NUMA imbalance such that LLCs do not get 2283 * imbalanced. 2284 */ 2285 for_each_cpu(i, cpu_map) { 2286 unsigned int imb = 0; 2287 unsigned int imb_span = 1; 2288 2289 for (sd = *per_cpu_ptr(d.sd, i); sd; sd = sd->parent) { 2290 struct sched_domain *child = sd->child; 2291 2292 if (!(sd->flags & SD_SHARE_PKG_RESOURCES) && child && 2293 (child->flags & SD_SHARE_PKG_RESOURCES)) { 2294 struct sched_domain __rcu *top_p; 2295 unsigned int nr_llcs; 2296 2297 /* 2298 * For a single LLC per node, allow an 2299 * imbalance up to 25% of the node. This is an 2300 * arbitrary cutoff based on SMT-2 to balance 2301 * between memory bandwidth and avoiding 2302 * premature sharing of HT resources and SMT-4 2303 * or SMT-8 *may* benefit from a different 2304 * cutoff. 2305 * 2306 * For multiple LLCs, allow an imbalance 2307 * until multiple tasks would share an LLC 2308 * on one node while LLCs on another node 2309 * remain idle. 2310 */ 2311 nr_llcs = sd->span_weight / child->span_weight; 2312 if (nr_llcs == 1) 2313 imb = sd->span_weight >> 2; 2314 else 2315 imb = nr_llcs; 2316 sd->imb_numa_nr = imb; 2317 2318 /* Set span based on the first NUMA domain. */ 2319 top_p = sd->parent; 2320 while (top_p && !(top_p->flags & SD_NUMA)) { 2321 top_p = top_p->parent; 2322 } 2323 imb_span = top_p ? top_p->span_weight : sd->span_weight; 2324 } else { 2325 int factor = max(1U, (sd->span_weight / imb_span)); 2326 2327 sd->imb_numa_nr = imb * factor; 2328 } 2329 } 2330 } 2331 2332 /* Calculate CPU capacity for physical packages and nodes */ 2333 for (i = nr_cpumask_bits-1; i >= 0; i--) { 2334 if (!cpumask_test_cpu(i, cpu_map)) 2335 continue; 2336 2337 for (sd = *per_cpu_ptr(d.sd, i); sd; sd = sd->parent) { 2338 claim_allocations(i, sd); 2339 init_sched_groups_capacity(i, sd); 2340 } 2341 } 2342 2343 /* Attach the domains */ 2344 rcu_read_lock(); 2345 for_each_cpu(i, cpu_map) { 2346 rq = cpu_rq(i); 2347 sd = *per_cpu_ptr(d.sd, i); 2348 2349 /* Use READ_ONCE()/WRITE_ONCE() to avoid load/store tearing: */ 2350 if (rq->cpu_capacity_orig > READ_ONCE(d.rd->max_cpu_capacity)) 2351 WRITE_ONCE(d.rd->max_cpu_capacity, rq->cpu_capacity_orig); 2352 2353 cpu_attach_domain(sd, d.rd, i); 2354 } 2355 rcu_read_unlock(); 2356 2357 if (has_asym) 2358 static_branch_inc_cpuslocked(&sched_asym_cpucapacity); 2359 2360 if (rq && sched_debug_verbose) { 2361 pr_info("root domain span: %*pbl (max cpu_capacity = %lu)\n", 2362 cpumask_pr_args(cpu_map), rq->rd->max_cpu_capacity); 2363 } 2364 2365 ret = 0; 2366 error: 2367 __free_domain_allocs(&d, alloc_state, cpu_map); 2368 2369 return ret; 2370 } 2371 2372 /* Current sched domains: */ 2373 static cpumask_var_t *doms_cur; 2374 2375 /* Number of sched domains in 'doms_cur': */ 2376 static int ndoms_cur; 2377 2378 /* Attributes of custom domains in 'doms_cur' */ 2379 static struct sched_domain_attr *dattr_cur; 2380 2381 /* 2382 * Special case: If a kmalloc() of a doms_cur partition (array of 2383 * cpumask) fails, then fallback to a single sched domain, 2384 * as determined by the single cpumask fallback_doms. 2385 */ 2386 static cpumask_var_t fallback_doms; 2387 2388 /* 2389 * arch_update_cpu_topology lets virtualized architectures update the 2390 * CPU core maps. It is supposed to return 1 if the topology changed 2391 * or 0 if it stayed the same. 2392 */ 2393 int __weak arch_update_cpu_topology(void) 2394 { 2395 return 0; 2396 } 2397 2398 cpumask_var_t *alloc_sched_domains(unsigned int ndoms) 2399 { 2400 int i; 2401 cpumask_var_t *doms; 2402 2403 doms = kmalloc_array(ndoms, sizeof(*doms), GFP_KERNEL); 2404 if (!doms) 2405 return NULL; 2406 for (i = 0; i < ndoms; i++) { 2407 if (!alloc_cpumask_var(&doms[i], GFP_KERNEL)) { 2408 free_sched_domains(doms, i); 2409 return NULL; 2410 } 2411 } 2412 return doms; 2413 } 2414 2415 void free_sched_domains(cpumask_var_t doms[], unsigned int ndoms) 2416 { 2417 unsigned int i; 2418 for (i = 0; i < ndoms; i++) 2419 free_cpumask_var(doms[i]); 2420 kfree(doms); 2421 } 2422 2423 /* 2424 * Set up scheduler domains and groups. For now this just excludes isolated 2425 * CPUs, but could be used to exclude other special cases in the future. 2426 */ 2427 int sched_init_domains(const struct cpumask *cpu_map) 2428 { 2429 int err; 2430 2431 zalloc_cpumask_var(&sched_domains_tmpmask, GFP_KERNEL); 2432 zalloc_cpumask_var(&sched_domains_tmpmask2, GFP_KERNEL); 2433 zalloc_cpumask_var(&fallback_doms, GFP_KERNEL); 2434 2435 arch_update_cpu_topology(); 2436 asym_cpu_capacity_scan(); 2437 ndoms_cur = 1; 2438 doms_cur = alloc_sched_domains(ndoms_cur); 2439 if (!doms_cur) 2440 doms_cur = &fallback_doms; 2441 cpumask_and(doms_cur[0], cpu_map, housekeeping_cpumask(HK_TYPE_DOMAIN)); 2442 err = build_sched_domains(doms_cur[0], NULL); 2443 2444 return err; 2445 } 2446 2447 /* 2448 * Detach sched domains from a group of CPUs specified in cpu_map 2449 * These CPUs will now be attached to the NULL domain 2450 */ 2451 static void detach_destroy_domains(const struct cpumask *cpu_map) 2452 { 2453 unsigned int cpu = cpumask_any(cpu_map); 2454 int i; 2455 2456 if (rcu_access_pointer(per_cpu(sd_asym_cpucapacity, cpu))) 2457 static_branch_dec_cpuslocked(&sched_asym_cpucapacity); 2458 2459 rcu_read_lock(); 2460 for_each_cpu(i, cpu_map) 2461 cpu_attach_domain(NULL, &def_root_domain, i); 2462 rcu_read_unlock(); 2463 } 2464 2465 /* handle null as "default" */ 2466 static int dattrs_equal(struct sched_domain_attr *cur, int idx_cur, 2467 struct sched_domain_attr *new, int idx_new) 2468 { 2469 struct sched_domain_attr tmp; 2470 2471 /* Fast path: */ 2472 if (!new && !cur) 2473 return 1; 2474 2475 tmp = SD_ATTR_INIT; 2476 2477 return !memcmp(cur ? (cur + idx_cur) : &tmp, 2478 new ? (new + idx_new) : &tmp, 2479 sizeof(struct sched_domain_attr)); 2480 } 2481 2482 /* 2483 * Partition sched domains as specified by the 'ndoms_new' 2484 * cpumasks in the array doms_new[] of cpumasks. This compares 2485 * doms_new[] to the current sched domain partitioning, doms_cur[]. 2486 * It destroys each deleted domain and builds each new domain. 2487 * 2488 * 'doms_new' is an array of cpumask_var_t's of length 'ndoms_new'. 2489 * The masks don't intersect (don't overlap.) We should setup one 2490 * sched domain for each mask. CPUs not in any of the cpumasks will 2491 * not be load balanced. If the same cpumask appears both in the 2492 * current 'doms_cur' domains and in the new 'doms_new', we can leave 2493 * it as it is. 2494 * 2495 * The passed in 'doms_new' should be allocated using 2496 * alloc_sched_domains. This routine takes ownership of it and will 2497 * free_sched_domains it when done with it. If the caller failed the 2498 * alloc call, then it can pass in doms_new == NULL && ndoms_new == 1, 2499 * and partition_sched_domains() will fallback to the single partition 2500 * 'fallback_doms', it also forces the domains to be rebuilt. 2501 * 2502 * If doms_new == NULL it will be replaced with cpu_online_mask. 2503 * ndoms_new == 0 is a special case for destroying existing domains, 2504 * and it will not create the default domain. 2505 * 2506 * Call with hotplug lock and sched_domains_mutex held 2507 */ 2508 void partition_sched_domains_locked(int ndoms_new, cpumask_var_t doms_new[], 2509 struct sched_domain_attr *dattr_new) 2510 { 2511 bool __maybe_unused has_eas = false; 2512 int i, j, n; 2513 int new_topology; 2514 2515 lockdep_assert_held(&sched_domains_mutex); 2516 2517 /* Let the architecture update CPU core mappings: */ 2518 new_topology = arch_update_cpu_topology(); 2519 /* Trigger rebuilding CPU capacity asymmetry data */ 2520 if (new_topology) 2521 asym_cpu_capacity_scan(); 2522 2523 if (!doms_new) { 2524 WARN_ON_ONCE(dattr_new); 2525 n = 0; 2526 doms_new = alloc_sched_domains(1); 2527 if (doms_new) { 2528 n = 1; 2529 cpumask_and(doms_new[0], cpu_active_mask, 2530 housekeeping_cpumask(HK_TYPE_DOMAIN)); 2531 } 2532 } else { 2533 n = ndoms_new; 2534 } 2535 2536 /* Destroy deleted domains: */ 2537 for (i = 0; i < ndoms_cur; i++) { 2538 for (j = 0; j < n && !new_topology; j++) { 2539 if (cpumask_equal(doms_cur[i], doms_new[j]) && 2540 dattrs_equal(dattr_cur, i, dattr_new, j)) { 2541 struct root_domain *rd; 2542 2543 /* 2544 * This domain won't be destroyed and as such 2545 * its dl_bw->total_bw needs to be cleared. It 2546 * will be recomputed in function 2547 * update_tasks_root_domain(). 2548 */ 2549 rd = cpu_rq(cpumask_any(doms_cur[i]))->rd; 2550 dl_clear_root_domain(rd); 2551 goto match1; 2552 } 2553 } 2554 /* No match - a current sched domain not in new doms_new[] */ 2555 detach_destroy_domains(doms_cur[i]); 2556 match1: 2557 ; 2558 } 2559 2560 n = ndoms_cur; 2561 if (!doms_new) { 2562 n = 0; 2563 doms_new = &fallback_doms; 2564 cpumask_and(doms_new[0], cpu_active_mask, 2565 housekeeping_cpumask(HK_TYPE_DOMAIN)); 2566 } 2567 2568 /* Build new domains: */ 2569 for (i = 0; i < ndoms_new; i++) { 2570 for (j = 0; j < n && !new_topology; j++) { 2571 if (cpumask_equal(doms_new[i], doms_cur[j]) && 2572 dattrs_equal(dattr_new, i, dattr_cur, j)) 2573 goto match2; 2574 } 2575 /* No match - add a new doms_new */ 2576 build_sched_domains(doms_new[i], dattr_new ? dattr_new + i : NULL); 2577 match2: 2578 ; 2579 } 2580 2581 #if defined(CONFIG_ENERGY_MODEL) && defined(CONFIG_CPU_FREQ_GOV_SCHEDUTIL) 2582 /* Build perf. domains: */ 2583 for (i = 0; i < ndoms_new; i++) { 2584 for (j = 0; j < n && !sched_energy_update; j++) { 2585 if (cpumask_equal(doms_new[i], doms_cur[j]) && 2586 cpu_rq(cpumask_first(doms_cur[j]))->rd->pd) { 2587 has_eas = true; 2588 goto match3; 2589 } 2590 } 2591 /* No match - add perf. domains for a new rd */ 2592 has_eas |= build_perf_domains(doms_new[i]); 2593 match3: 2594 ; 2595 } 2596 sched_energy_set(has_eas); 2597 #endif 2598 2599 /* Remember the new sched domains: */ 2600 if (doms_cur != &fallback_doms) 2601 free_sched_domains(doms_cur, ndoms_cur); 2602 2603 kfree(dattr_cur); 2604 doms_cur = doms_new; 2605 dattr_cur = dattr_new; 2606 ndoms_cur = ndoms_new; 2607 2608 update_sched_domain_debugfs(); 2609 } 2610 2611 /* 2612 * Call with hotplug lock held 2613 */ 2614 void partition_sched_domains(int ndoms_new, cpumask_var_t doms_new[], 2615 struct sched_domain_attr *dattr_new) 2616 { 2617 mutex_lock(&sched_domains_mutex); 2618 partition_sched_domains_locked(ndoms_new, doms_new, dattr_new); 2619 mutex_unlock(&sched_domains_mutex); 2620 } 2621