kernel/sched/topology.c

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

DEFINITIONS
