kernel/sched/topology.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Scheduler topology setup/handling methods
   4  */
   5 #include <linux/sched.h>
   6 #include <linux/mutex.h>
   7
   8 #include "sched.h"
   9
  10 DEFINE_MUTEX(sched_domains_mutex);
  11
  12 /* Protected by sched_domains_mutex: */
  13 cpumask_var_t sched_domains_tmpmask;
  14 cpumask_var_t sched_domains_tmpmask2;
  15
  16 #ifdef CONFIG_SCHED_DEBUG
  17
  18 static int __init sched_debug_setup(char *str)
  19 {
  20         sched_debug_enabled = true;
  21
  22         return 0;
  23 }
  24 early_param("sched_debug", sched_debug_setup);
  25
  26 static inline bool sched_debug(void)
  27 {
  28         return sched_debug_enabled;
  29 }
  30
  31 static int sched_domain_debug_one(struct sched_domain *sd, int cpu, int level,
  32                                   struct cpumask *groupmask)
  33 {
  34         struct sched_group *group = sd->groups;
  35
  36         cpumask_clear(groupmask);
  37
  38         printk(KERN_DEBUG "%*s domain-%d: ", level, "", level);
  39
  40         if (!(sd->flags & SD_LOAD_BALANCE)) {
  41                 printk("does not load-balance\n");
  42                 if (sd->parent)
  43                         printk(KERN_ERR "ERROR: !SD_LOAD_BALANCE domain"
  44                                         " has parent");
  45                 return -1;
  46         }
  47
  48         printk(KERN_CONT "span=%*pbl level=%s\n",
  49                cpumask_pr_args(sched_domain_span(sd)), sd->name);
  50
  51         if (!cpumask_test_cpu(cpu, sched_domain_span(sd))) {
  52                 printk(KERN_ERR "ERROR: domain->span does not contain "
  53                                 "CPU%d\n", cpu);
  54         }
  55         if (!cpumask_test_cpu(cpu, sched_group_span(group))) {
  56                 printk(KERN_ERR "ERROR: domain->groups does not contain"
  57                                 " CPU%d\n", cpu);
  58         }
  59
  60         printk(KERN_DEBUG "%*s groups:", level + 1, "");
  61         do {
  62                 if (!group) {
  63                         printk("\n");
  64                         printk(KERN_ERR "ERROR: group is NULL\n");
  65                         break;
  66                 }
  67
  68                 if (!cpumask_weight(sched_group_span(group))) {
  69                         printk(KERN_CONT "\n");
  70                         printk(KERN_ERR "ERROR: empty group\n");
  71                         break;
  72                 }
  73
  74                 if (!(sd->flags & SD_OVERLAP) &&
  75                     cpumask_intersects(groupmask, sched_group_span(group))) {
  76                         printk(KERN_CONT "\n");
  77                         printk(KERN_ERR "ERROR: repeated CPUs\n");
  78                         break;
  79                 }
  80
  81                 cpumask_or(groupmask, groupmask, sched_group_span(group));
  82
  83                 printk(KERN_CONT " %d:{ span=%*pbl",
  84                                 group->sgc->id,
  85                                 cpumask_pr_args(sched_group_span(group)));
  86
  87                 if ((sd->flags & SD_OVERLAP) &&
  88                     !cpumask_equal(group_balance_mask(group), sched_group_span(group))) {
  89                         printk(KERN_CONT " mask=%*pbl",
  90                                 cpumask_pr_args(group_balance_mask(group)));
  91                 }
  92
  93                 if (group->sgc->capacity != SCHED_CAPACITY_SCALE)
  94                         printk(KERN_CONT " cap=%lu", group->sgc->capacity);
  95
  96                 if (group == sd->groups && sd->child &&
  97                     !cpumask_equal(sched_domain_span(sd->child),
  98                                    sched_group_span(group))) {
  99                         printk(KERN_ERR "ERROR: domain->groups does not match domain->child\n");
 100                 }
 101
 102                 printk(KERN_CONT " }");
 103
 104                 group = group->next;
 105
 106                 if (group != sd->groups)
 107                         printk(KERN_CONT ",");
 108
 109         } while (group != sd->groups);
 110         printk(KERN_CONT "\n");
 111
 112         if (!cpumask_equal(sched_domain_span(sd), groupmask))
 113                 printk(KERN_ERR "ERROR: groups don't span domain->span\n");
 114
 115         if (sd->parent &&
 116             !cpumask_subset(groupmask, sched_domain_span(sd->parent)))
 117                 printk(KERN_ERR "ERROR: parent span is not a superset "
 118                         "of domain->span\n");
 119         return 0;
 120 }
 121
 122 static void sched_domain_debug(struct sched_domain *sd, int cpu)
 123 {
 124         int level = 0;
 125
 126         if (!sched_debug_enabled)
 127                 return;
 128
 129         if (!sd) {
 130                 printk(KERN_DEBUG "CPU%d attaching NULL sched-domain.\n", cpu);
 131                 return;
 132         }
 133
 134         printk(KERN_DEBUG "CPU%d attaching sched-domain(s):\n", cpu);
 135
 136         for (;;) {
 137                 if (sched_domain_debug_one(sd, cpu, level, sched_domains_tmpmask))
 138                         break;
 139                 level++;
 140                 sd = sd->parent;
 141                 if (!sd)
 142                         break;
 143         }
 144 }
 145 #else /* !CONFIG_SCHED_DEBUG */
 146
 147 # define sched_debug_enabled 0
 148 # define sched_domain_debug(sd, cpu) do { } while (0)
 149 static inline bool sched_debug(void)
 150 {
 151         return false;
 152 }
 153 #endif /* CONFIG_SCHED_DEBUG */
 154
 155 static int sd_degenerate(struct sched_domain *sd)
 156 {
 157         if (cpumask_weight(sched_domain_span(sd)) == 1)
 158                 return 1;
 159
 160         /* Following flags need at least 2 groups */
 161         if (sd->flags & (SD_LOAD_BALANCE |
 162                          SD_BALANCE_NEWIDLE |
 163                          SD_BALANCE_FORK |
 164                          SD_BALANCE_EXEC |
 165                          SD_SHARE_CPUCAPACITY |
 166                          SD_ASYM_CPUCAPACITY |
 167                          SD_SHARE_PKG_RESOURCES |
 168                          SD_SHARE_POWERDOMAIN)) {
 169                 if (sd->groups != sd->groups->next)
 170                         return 0;
 171         }
 172
 173         /* Following flags don't use groups */
 174         if (sd->flags & (SD_WAKE_AFFINE))
 175                 return 0;
 176
 177         return 1;
 178 }
 179
 180 static int
 181 sd_parent_degenerate(struct sched_domain *sd, struct sched_domain *parent)
 182 {
 183         unsigned long cflags = sd->flags, pflags = parent->flags;
 184
 185         if (sd_degenerate(parent))
 186                 return 1;
 187
 188         if (!cpumask_equal(sched_domain_span(sd), sched_domain_span(parent)))
 189                 return 0;
 190
 191         /* Flags needing groups don't count if only 1 group in parent */
 192         if (parent->groups == parent->groups->next) {
 193                 pflags &= ~(SD_LOAD_BALANCE |
 194                                 SD_BALANCE_NEWIDLE |
 195                                 SD_BALANCE_FORK |
 196                                 SD_BALANCE_EXEC |
 197                                 SD_ASYM_CPUCAPACITY |
 198                                 SD_SHARE_CPUCAPACITY |
 199                                 SD_SHARE_PKG_RESOURCES |
 200                                 SD_PREFER_SIBLING |
 201                                 SD_SHARE_POWERDOMAIN);
 202                 if (nr_node_ids == 1)
 203                         pflags &= ~SD_SERIALIZE;
 204         }
 205         if (~cflags & pflags)
 206                 return 0;
 207
 208         return 1;
 209 }
 210
 211 static void free_rootdomain(struct rcu_head *rcu)
 212 {
 213         struct root_domain *rd = container_of(rcu, struct root_domain, rcu);
 214
 215         cpupri_cleanup(&rd->cpupri);
 216         cpudl_cleanup(&rd->cpudl);
 217         free_cpumask_var(rd->dlo_mask);
 218         free_cpumask_var(rd->rto_mask);
 219         free_cpumask_var(rd->online);
 220         free_cpumask_var(rd->span);
 221         kfree(rd);
 222 }
 223
 224 void rq_attach_root(struct rq *rq, struct root_domain *rd)
 225 {
 226         struct root_domain *old_rd = NULL;
 227         unsigned long flags;
 228
 229         raw_spin_lock_irqsave(&rq->lock, flags);
 230
 231         if (rq->rd) {
 232                 old_rd = rq->rd;
 233
 234                 if (cpumask_test_cpu(rq->cpu, old_rd->online))
 235                         set_rq_offline(rq);
 236
 237                 cpumask_clear_cpu(rq->cpu, old_rd->span);
 238
 239                 /*
 240                  * If we dont want to free the old_rd yet then
 241                  * set old_rd to NULL to skip the freeing later
 242                  * in this function:
 243                  */
 244                 if (!atomic_dec_and_test(&old_rd->refcount))
 245                         old_rd = NULL;
 246         }
 247
 248         atomic_inc(&rd->refcount);
 249         rq->rd = rd;
 250
 251         cpumask_set_cpu(rq->cpu, rd->span);
 252         if (cpumask_test_cpu(rq->cpu, cpu_active_mask))
 253                 set_rq_online(rq);
 254
 255         raw_spin_unlock_irqrestore(&rq->lock, flags);
 256
 257         if (old_rd)
 258                 call_rcu_sched(&old_rd->rcu, free_rootdomain);
 259 }
 260
 261 static int init_rootdomain(struct root_domain *rd)
 262 {
 263         if (!zalloc_cpumask_var(&rd->span, GFP_KERNEL))
 264                 goto out;
 265         if (!zalloc_cpumask_var(&rd->online, GFP_KERNEL))
 266                 goto free_span;
 267         if (!zalloc_cpumask_var(&rd->dlo_mask, GFP_KERNEL))
 268                 goto free_online;
 269         if (!zalloc_cpumask_var(&rd->rto_mask, GFP_KERNEL))
 270                 goto free_dlo_mask;
 271
 272         init_dl_bw(&rd->dl_bw);
 273         if (cpudl_init(&rd->cpudl) != 0)
 274                 goto free_rto_mask;
 275
 276         if (cpupri_init(&rd->cpupri) != 0)
 277                 goto free_cpudl;
 278         return 0;
 279
 280 free_cpudl:
 281         cpudl_cleanup(&rd->cpudl);
 282 free_rto_mask:
 283         free_cpumask_var(rd->rto_mask);
 284 free_dlo_mask:
 285         free_cpumask_var(rd->dlo_mask);
 286 free_online:
 287         free_cpumask_var(rd->online);
 288 free_span:
 289         free_cpumask_var(rd->span);
 290 out:
 291         return -ENOMEM;
 292 }
 293
 294 /*
 295  * By default the system creates a single root-domain with all CPUs as
 296  * members (mimicking the global state we have today).
 297  */
 298 struct root_domain def_root_domain;
 299
 300 void init_defrootdomain(void)
 301 {
 302         init_rootdomain(&def_root_domain);
 303
 304         atomic_set(&def_root_domain.refcount, 1);
 305 }
 306
 307 static struct root_domain *alloc_rootdomain(void)
 308 {
 309         struct root_domain *rd;
 310
 311         rd = kzalloc(sizeof(*rd), GFP_KERNEL);
 312         if (!rd)
 313                 return NULL;
 314
 315         if (init_rootdomain(rd) != 0) {
 316                 kfree(rd);
 317                 return NULL;
 318         }
 319
 320         return rd;
 321 }
 322
 323 static void free_sched_groups(struct sched_group *sg, int free_sgc)
 324 {
 325         struct sched_group *tmp, *first;
 326
 327         if (!sg)
 328                 return;
 329
 330         first = sg;
 331         do {
 332                 tmp = sg->next;
 333
 334                 if (free_sgc && atomic_dec_and_test(&sg->sgc->ref))
 335                         kfree(sg->sgc);
 336
 337                 if (atomic_dec_and_test(&sg->ref))
 338                         kfree(sg);
 339                 sg = tmp;
 340         } while (sg != first);
 341 }
 342
 343 static void destroy_sched_domain(struct sched_domain *sd)
 344 {
 345         /*
 346          * A normal sched domain may have multiple group references, an
 347          * overlapping domain, having private groups, only one.  Iterate,
 348          * dropping group/capacity references, freeing where none remain.
 349          */
 350         free_sched_groups(sd->groups, 1);
 351
 352         if (sd->shared && atomic_dec_and_test(&sd->shared->ref))
 353                 kfree(sd->shared);
 354         kfree(sd);
 355 }
 356
 357 static void destroy_sched_domains_rcu(struct rcu_head *rcu)
 358 {
 359         struct sched_domain *sd = container_of(rcu, struct sched_domain, rcu);
 360
 361         while (sd) {
 362                 struct sched_domain *parent = sd->parent;
 363                 destroy_sched_domain(sd);
 364                 sd = parent;
 365         }
 366 }
 367
 368 static void destroy_sched_domains(struct sched_domain *sd)
 369 {
 370         if (sd)
 371                 call_rcu(&sd->rcu, destroy_sched_domains_rcu);
 372 }
 373
 374 /*
 375  * Keep a special pointer to the highest sched_domain that has
 376  * SD_SHARE_PKG_RESOURCE set (Last Level Cache Domain) for this
 377  * allows us to avoid some pointer chasing select_idle_sibling().
 378  *
 379  * Also keep a unique ID per domain (we use the first CPU number in
 380  * the cpumask of the domain), this allows us to quickly tell if
 381  * two CPUs are in the same cache domain, see cpus_share_cache().
 382  */
 383 DEFINE_PER_CPU(struct sched_domain *, sd_llc);
 384 DEFINE_PER_CPU(int, sd_llc_size);
 385 DEFINE_PER_CPU(int, sd_llc_id);
 386 DEFINE_PER_CPU(struct sched_domain_shared *, sd_llc_shared);
 387 DEFINE_PER_CPU(struct sched_domain *, sd_numa);
 388 DEFINE_PER_CPU(struct sched_domain *, sd_asym);
 389
 390 static void update_top_cache_domain(int cpu)
 391 {
 392         struct sched_domain_shared *sds = NULL;
 393         struct sched_domain *sd;
 394         int id = cpu;
 395         int size = 1;
 396
 397         sd = highest_flag_domain(cpu, SD_SHARE_PKG_RESOURCES);
 398         if (sd) {
 399                 id = cpumask_first(sched_domain_span(sd));
 400                 size = cpumask_weight(sched_domain_span(sd));
 401                 sds = sd->shared;
 402         }
 403
 404         rcu_assign_pointer(per_cpu(sd_llc, cpu), sd);
 405         per_cpu(sd_llc_size, cpu) = size;
 406         per_cpu(sd_llc_id, cpu) = id;
 407         rcu_assign_pointer(per_cpu(sd_llc_shared, cpu), sds);
 408
 409         sd = lowest_flag_domain(cpu, SD_NUMA);
 410         rcu_assign_pointer(per_cpu(sd_numa, cpu), sd);
 411
 412         sd = highest_flag_domain(cpu, SD_ASYM_PACKING);
 413         rcu_assign_pointer(per_cpu(sd_asym, cpu), sd);
 414 }
 415
 416 /*
 417  * Attach the domain 'sd' to 'cpu' as its base domain. Callers must
 418  * hold the hotplug lock.
 419  */
 420 static void
 421 cpu_attach_domain(struct sched_domain *sd, struct root_domain *rd, int cpu)
 422 {
 423         struct rq *rq = cpu_rq(cpu);
 424         struct sched_domain *tmp;
 425
 426         /* Remove the sched domains which do not contribute to scheduling. */
 427         for (tmp = sd; tmp; ) {
 428                 struct sched_domain *parent = tmp->parent;
 429                 if (!parent)
 430                         break;
 431
 432                 if (sd_parent_degenerate(tmp, parent)) {
 433                         tmp->parent = parent->parent;
 434                         if (parent->parent)
 435                                 parent->parent->child = tmp;
 436                         /*
 437                          * Transfer SD_PREFER_SIBLING down in case of a
 438                          * degenerate parent; the spans match for this
 439                          * so the property transfers.
 440                          */
 441                         if (parent->flags & SD_PREFER_SIBLING)
 442                                 tmp->flags |= SD_PREFER_SIBLING;
 443                         destroy_sched_domain(parent);
 444                 } else
 445                         tmp = tmp->parent;
 446         }
 447
 448         if (sd && sd_degenerate(sd)) {
 449                 tmp = sd;
 450                 sd = sd->parent;
 451                 destroy_sched_domain(tmp);
 452                 if (sd)
 453                         sd->child = NULL;
 454         }
 455
 456         sched_domain_debug(sd, cpu);
 457
 458         rq_attach_root(rq, rd);
 459         tmp = rq->sd;
 460         rcu_assign_pointer(rq->sd, sd);
 461         dirty_sched_domain_sysctl(cpu);
 462         destroy_sched_domains(tmp);
 463
 464         update_top_cache_domain(cpu);
 465 }
 466
 467 /* Setup the mask of CPUs configured for isolated domains */
 468 static int __init isolated_cpu_setup(char *str)
 469 {
 470         int ret;
 471
 472         alloc_bootmem_cpumask_var(&cpu_isolated_map);
 473         ret = cpulist_parse(str, cpu_isolated_map);
 474         if (ret) {
 475                 pr_err("sched: Error, all isolcpus= values must be between 0 and %u\n", nr_cpu_ids);
 476                 return 0;
 477         }
 478         return 1;
 479 }
 480 __setup("isolcpus=", isolated_cpu_setup);
 481
 482 struct s_data {
 483         struct sched_domain ** __percpu sd;
 484         struct root_domain      *rd;
 485 };
 486
 487 enum s_alloc {
 488         sa_rootdomain,
 489         sa_sd,
 490         sa_sd_storage,
 491         sa_none,
 492 };
 493
 494 /*
 495  * Return the canonical balance CPU for this group, this is the first CPU
 496  * of this group that's also in the balance mask.
 497  *
 498  * The balance mask are all those CPUs that could actually end up at this
 499  * group. See build_balance_mask().
 500  *
 501  * Also see should_we_balance().
 502  */
 503 int group_balance_cpu(struct sched_group *sg)
 504 {
 505         return cpumask_first(group_balance_mask(sg));
 506 }
 507
 508
 509 /*
 510  * NUMA topology (first read the regular topology blurb below)
 511  *
 512  * Given a node-distance table, for example:
 513  *
 514  *   node   0   1   2   3
 515  *     0:  10  20  30  20
 516  *     1:  20  10  20  30
 517  *     2:  30  20  10  20
 518  *     3:  20  30  20  10
 519  *
 520  * which represents a 4 node ring topology like:
 521  *
 522  *   0 ----- 1
 523  *   |       |
 524  *   |       |
 525  *   |       |
 526  *   3 ----- 2
 527  *
 528  * We want to construct domains and groups to represent this. The way we go
 529  * about doing this is to build the domains on 'hops'. For each NUMA level we
 530  * construct the mask of all nodes reachable in @level hops.
 531  *
 532  * For the above NUMA topology that gives 3 levels:
 533  *
 534  * NUMA-2       0-3             0-3             0-3             0-3
 535  *  groups:     {0-1,3},{1-3}   {0-2},{0,2-3}   {1-3},{0-1,3}   {0,2-3},{0-2}
 536  *
 537  * NUMA-1       0-1,3           0-2             1-3             0,2-3
 538  *  groups:     {0},{1},{3}     {0},{1},{2}     {1},{2},{3}     {0},{2},{3}
 539  *
 540  * NUMA-0       0               1               2               3
 541  *
 542  *
 543  * As can be seen; things don't nicely line up as with the regular topology.
 544  * When we iterate a domain in child domain chunks some nodes can be
 545  * represented multiple times -- hence the "overlap" naming for this part of
 546  * the topology.
 547  *
 548  * In order to minimize this overlap, we only build enough groups to cover the
 549  * domain. For instance Node-0 NUMA-2 would only get groups: 0-1,3 and 1-3.
 550  *
 551  * Because:
 552  *
 553  *  - the first group of each domain is its child domain; this
 554  *    gets us the first 0-1,3
 555  *  - the only uncovered node is 2, who's child domain is 1-3.
 556  *
 557  * However, because of the overlap, computing a unique CPU for each group is
 558  * more complicated. Consider for instance the groups of NODE-1 NUMA-2, both
 559  * groups include the CPUs of Node-0, while those CPUs would not in fact ever
 560  * end up at those groups (they would end up in group: 0-1,3).
 561  *
 562  * To correct this we have to introduce the group balance mask. This mask
 563  * will contain those CPUs in the group that can reach this group given the
 564  * (child) domain tree.
 565  *
 566  * With this we can once again compute balance_cpu and sched_group_capacity
 567  * relations.
 568  *
 569  * XXX include words on how balance_cpu is unique and therefore can be
 570  * used for sched_group_capacity links.
 571  *
 572  *
 573  * Another 'interesting' topology is:
 574  *
 575  *   node   0   1   2   3
 576  *     0:  10  20  20  30
 577  *     1:  20  10  20  20
 578  *     2:  20  20  10  20
 579  *     3:  30  20  20  10
 580  *
 581  * Which looks a little like:
 582  *
 583  *   0 ----- 1
 584  *   |     / |
 585  *   |   /   |
 586  *   | /     |
 587  *   2 ----- 3
 588  *
 589  * This topology is asymmetric, nodes 1,2 are fully connected, but nodes 0,3
 590  * are not.
 591  *
 592  * This leads to a few particularly weird cases where the sched_domain's are
 593  * not of the same number for each cpu. Consider:
 594  *
 595  * NUMA-2       0-3                                             0-3
 596  *  groups:     {0-2},{1-3}                                     {1-3},{0-2}
 597  *
 598  * NUMA-1       0-2             0-3             0-3             1-3
 599  *
 600  * NUMA-0       0               1               2               3
 601  *
 602  */
 603
 604
 605 /*
 606  * Build the balance mask; it contains only those CPUs that can arrive at this
 607  * group and should be considered to continue balancing.
 608  *
 609  * We do this during the group creation pass, therefore the group information
 610  * isn't complete yet, however since each group represents a (child) domain we
 611  * can fully construct this using the sched_domain bits (which are already
 612  * complete).
 613  */
 614 static void
 615 build_balance_mask(struct sched_domain *sd, struct sched_group *sg, struct cpumask *mask)
 616 {
 617         const struct cpumask *sg_span = sched_group_span(sg);
 618         struct sd_data *sdd = sd->private;
 619         struct sched_domain *sibling;
 620         int i;
 621
 622         cpumask_clear(mask);
 623
 624         for_each_cpu(i, sg_span) {
 625                 sibling = *per_cpu_ptr(sdd->sd, i);
 626
 627                 /*
 628                  * Can happen in the asymmetric case, where these siblings are
 629                  * unused. The mask will not be empty because those CPUs that
 630                  * do have the top domain _should_ span the domain.
 631                  */
 632                 if (!sibling->child)
 633                         continue;
 634
 635                 /* If we would not end up here, we can't continue from here */
 636                 if (!cpumask_equal(sg_span, sched_domain_span(sibling->child)))
 637                         continue;
 638
 639                 cpumask_set_cpu(i, mask);
 640         }
 641
 642         /* We must not have empty masks here */
 643         WARN_ON_ONCE(cpumask_empty(mask));
 644 }
 645
 646 /*
 647  * XXX: This creates per-node group entries; since the load-balancer will
 648  * immediately access remote memory to construct this group's load-balance
 649  * statistics having the groups node local is of dubious benefit.
 650  */
 651 static struct sched_group *
 652 build_group_from_child_sched_domain(struct sched_domain *sd, int cpu)
 653 {
 654         struct sched_group *sg;
 655         struct cpumask *sg_span;
 656
 657         sg = kzalloc_node(sizeof(struct sched_group) + cpumask_size(),
 658                         GFP_KERNEL, cpu_to_node(cpu));
 659
 660         if (!sg)
 661                 return NULL;
 662
 663         sg_span = sched_group_span(sg);
 664         if (sd->child)
 665                 cpumask_copy(sg_span, sched_domain_span(sd->child));
 666         else
 667                 cpumask_copy(sg_span, sched_domain_span(sd));
 668
 669         atomic_inc(&sg->ref);
 670         return sg;
 671 }
 672
 673 static void init_overlap_sched_group(struct sched_domain *sd,
 674                                      struct sched_group *sg)
 675 {
 676         struct cpumask *mask = sched_domains_tmpmask2;
 677         struct sd_data *sdd = sd->private;
 678         struct cpumask *sg_span;
 679         int cpu;
 680
 681         build_balance_mask(sd, sg, mask);
 682         cpu = cpumask_first_and(sched_group_span(sg), mask);
 683
 684         sg->sgc = *per_cpu_ptr(sdd->sgc, cpu);
 685         if (atomic_inc_return(&sg->sgc->ref) == 1)
 686                 cpumask_copy(group_balance_mask(sg), mask);
 687         else
 688                 WARN_ON_ONCE(!cpumask_equal(group_balance_mask(sg), mask));
 689
 690         /*
 691          * Initialize sgc->capacity such that even if we mess up the
 692          * domains and no possible iteration will get us here, we won't
 693          * die on a /0 trap.
 694          */
 695         sg_span = sched_group_span(sg);
 696         sg->sgc->capacity = SCHED_CAPACITY_SCALE * cpumask_weight(sg_span);
 697         sg->sgc->min_capacity = SCHED_CAPACITY_SCALE;
 698 }
 699
 700 static int
 701 build_overlap_sched_groups(struct sched_domain *sd, int cpu)
 702 {
 703         struct sched_group *first = NULL, *last = NULL, *sg;
 704         const struct cpumask *span = sched_domain_span(sd);
 705         struct cpumask *covered = sched_domains_tmpmask;
 706         struct sd_data *sdd = sd->private;
 707         struct sched_domain *sibling;
 708         int i;
 709
 710         cpumask_clear(covered);
 711
 712         for_each_cpu_wrap(i, span, cpu) {
 713                 struct cpumask *sg_span;
 714
 715                 if (cpumask_test_cpu(i, covered))
 716                         continue;
 717
 718                 sibling = *per_cpu_ptr(sdd->sd, i);
 719
 720                 /*
 721                  * Asymmetric node setups can result in situations where the
 722                  * domain tree is of unequal depth, make sure to skip domains
 723                  * that already cover the entire range.
 724                  *
 725                  * In that case build_sched_domains() will have terminated the
 726                  * iteration early and our sibling sd spans will be empty.
 727                  * Domains should always include the CPU they're built on, so
 728                  * check that.
 729                  */
 730                 if (!cpumask_test_cpu(i, sched_domain_span(sibling)))
 731                         continue;
 732
 733                 sg = build_group_from_child_sched_domain(sibling, cpu);
 734                 if (!sg)
 735                         goto fail;
 736
 737                 sg_span = sched_group_span(sg);
 738                 cpumask_or(covered, covered, sg_span);
 739
 740                 init_overlap_sched_group(sd, sg);
 741
 742                 if (!first)
 743                         first = sg;
 744                 if (last)
 745                         last->next = sg;
 746                 last = sg;
 747                 last->next = first;
 748         }
 749         sd->groups = first;
 750
 751         return 0;
 752
 753 fail:
 754         free_sched_groups(first, 0);
 755
 756         return -ENOMEM;
 757 }
 758
 759
 760 /*
 761  * Package topology (also see the load-balance blurb in fair.c)
 762  *
 763  * The scheduler builds a tree structure to represent a number of important
 764  * topology features. By default (default_topology[]) these include:
 765  *
 766  *  - Simultaneous multithreading (SMT)
 767  *  - Multi-Core Cache (MC)
 768  *  - Package (DIE)
 769  *
 770  * Where the last one more or less denotes everything up to a NUMA node.
 771  *
 772  * The tree consists of 3 primary data structures:
 773  *
 774  *      sched_domain -> sched_group -> sched_group_capacity
 775  *          ^ ^             ^ ^
 776  *          `-'             `-'
 777  *
 778  * The sched_domains are per-cpu and have a two way link (parent & child) and
 779  * denote the ever growing mask of CPUs belonging to that level of topology.
 780  *
 781  * Each sched_domain has a circular (double) linked list of sched_group's, each
 782  * denoting the domains of the level below (or individual CPUs in case of the
 783  * first domain level). The sched_group linked by a sched_domain includes the
 784  * CPU of that sched_domain [*].
 785  *
 786  * Take for instance a 2 threaded, 2 core, 2 cache cluster part:
 787  *
 788  * CPU   0   1   2   3   4   5   6   7
 789  *
 790  * DIE  [                             ]
 791  * MC   [             ] [             ]
 792  * SMT  [     ] [     ] [     ] [     ]
 793  *
 794  *  - or -
 795  *
 796  * DIE  0-7 0-7 0-7 0-7 0-7 0-7 0-7 0-7
 797  * MC   0-3 0-3 0-3 0-3 4-7 4-7 4-7 4-7
 798  * SMT  0-1 0-1 2-3 2-3 4-5 4-5 6-7 6-7
 799  *
 800  * CPU   0   1   2   3   4   5   6   7
 801  *
 802  * One way to think about it is: sched_domain moves you up and down among these
 803  * topology levels, while sched_group moves you sideways through it, at child
 804  * domain granularity.
 805  *
 806  * sched_group_capacity ensures each unique sched_group has shared storage.
 807  *
 808  * There are two related construction problems, both require a CPU that
 809  * uniquely identify each group (for a given domain):
 810  *
 811  *  - The first is the balance_cpu (see should_we_balance() and the
 812  *    load-balance blub in fair.c); for each group we only want 1 CPU to
 813  *    continue balancing at a higher domain.
 814  *
 815  *  - The second is the sched_group_capacity; we want all identical groups
 816  *    to share a single sched_group_capacity.
 817  *
 818  * Since these topologies are exclusive by construction. That is, its
 819  * impossible for an SMT thread to belong to multiple cores, and cores to
 820  * be part of multiple caches. There is a very clear and unique location
 821  * for each CPU in the hierarchy.
 822  *
 823  * Therefore computing a unique CPU for each group is trivial (the iteration
 824  * mask is redundant and set all 1s; all CPUs in a group will end up at _that_
 825  * group), we can simply pick the first CPU in each group.
 826  *
 827  *
 828  * [*] in other words, the first group of each domain is its child domain.
 829  */
 830
 831 static struct sched_group *get_group(int cpu, struct sd_data *sdd)
 832 {
 833         struct sched_domain *sd = *per_cpu_ptr(sdd->sd, cpu);
 834         struct sched_domain *child = sd->child;
 835         struct sched_group *sg;
 836
 837         if (child)
 838                 cpu = cpumask_first(sched_domain_span(child));
 839
 840         sg = *per_cpu_ptr(sdd->sg, cpu);
 841         sg->sgc = *per_cpu_ptr(sdd->sgc, cpu);
 842
 843         /* For claim_allocations: */
 844         atomic_inc(&sg->ref);
 845         atomic_inc(&sg->sgc->ref);
 846
 847         if (child) {
 848                 cpumask_copy(sched_group_span(sg), sched_domain_span(child));
 849                 cpumask_copy(group_balance_mask(sg), sched_group_span(sg));
 850         } else {
 851                 cpumask_set_cpu(cpu, sched_group_span(sg));
 852                 cpumask_set_cpu(cpu, group_balance_mask(sg));
 853         }
 854
 855         sg->sgc->capacity = SCHED_CAPACITY_SCALE * cpumask_weight(sched_group_span(sg));
 856         sg->sgc->min_capacity = SCHED_CAPACITY_SCALE;
 857
 858         return sg;
 859 }
 860
 861 /*
 862  * build_sched_groups will build a circular linked list of the groups
 863  * covered by the given span, and will set each group's ->cpumask correctly,
 864  * and ->cpu_capacity to 0.
 865  *
 866  * Assumes the sched_domain tree is fully constructed
 867  */
 868 static int
 869 build_sched_groups(struct sched_domain *sd, int cpu)
 870 {
 871         struct sched_group *first = NULL, *last = NULL;
 872         struct sd_data *sdd = sd->private;
 873         const struct cpumask *span = sched_domain_span(sd);
 874         struct cpumask *covered;
 875         int i;
 876
 877         lockdep_assert_held(&sched_domains_mutex);
 878         covered = sched_domains_tmpmask;
 879
 880         cpumask_clear(covered);
 881
 882         for_each_cpu_wrap(i, span, cpu) {
 883                 struct sched_group *sg;
 884
 885                 if (cpumask_test_cpu(i, covered))
 886                         continue;
 887
 888                 sg = get_group(i, sdd);
 889
 890                 cpumask_or(covered, covered, sched_group_span(sg));
 891
 892                 if (!first)
 893                         first = sg;
 894                 if (last)
 895                         last->next = sg;
 896                 last = sg;
 897         }
 898         last->next = first;
 899         sd->groups = first;
 900
 901         return 0;
 902 }
 903
 904 /*
 905  * Initialize sched groups cpu_capacity.
 906  *
 907  * cpu_capacity indicates the capacity of sched group, which is used while
 908  * distributing the load between different sched groups in a sched domain.
 909  * Typically cpu_capacity for all the groups in a sched domain will be same
 910  * unless there are asymmetries in the topology. If there are asymmetries,
 911  * group having more cpu_capacity will pickup more load compared to the
 912  * group having less cpu_capacity.
 913  */
 914 static void init_sched_groups_capacity(int cpu, struct sched_domain *sd)
 915 {
 916         struct sched_group *sg = sd->groups;
 917
 918         WARN_ON(!sg);
 919
 920         do {
 921                 int cpu, max_cpu = -1;
 922
 923                 sg->group_weight = cpumask_weight(sched_group_span(sg));
 924
 925                 if (!(sd->flags & SD_ASYM_PACKING))
 926                         goto next;
 927
 928                 for_each_cpu(cpu, sched_group_span(sg)) {
 929                         if (max_cpu < 0)
 930                                 max_cpu = cpu;
 931                         else if (sched_asym_prefer(cpu, max_cpu))
 932                                 max_cpu = cpu;
 933                 }
 934                 sg->asym_prefer_cpu = max_cpu;
 935
 936 next:
 937                 sg = sg->next;
 938         } while (sg != sd->groups);
 939
 940         if (cpu != group_balance_cpu(sg))
 941                 return;
 942
 943         update_group_capacity(sd, cpu);
 944 }
 945
 946 /*
 947  * Initializers for schedule domains
 948  * Non-inlined to reduce accumulated stack pressure in build_sched_domains()
 949  */
 950
 951 static int default_relax_domain_level = -1;
 952 int sched_domain_level_max;
 953
 954 static int __init setup_relax_domain_level(char *str)
 955 {
 956         if (kstrtoint(str, 0, &default_relax_domain_level))
 957                 pr_warn("Unable to set relax_domain_level\n");
 958
 959         return 1;
 960 }
 961 __setup("relax_domain_level=", setup_relax_domain_level);
 962
 963 static void set_domain_attribute(struct sched_domain *sd,
 964                                  struct sched_domain_attr *attr)
 965 {
 966         int request;
 967
 968         if (!attr || attr->relax_domain_level < 0) {
 969                 if (default_relax_domain_level < 0)
 970                         return;
 971                 else
 972                         request = default_relax_domain_level;
 973         } else
 974                 request = attr->relax_domain_level;
 975         if (request < sd->level) {
 976                 /* Turn off idle balance on this domain: */
 977                 sd->flags &= ~(SD_BALANCE_WAKE|SD_BALANCE_NEWIDLE);
 978         } else {
 979                 /* Turn on idle balance on this domain: */
 980                 sd->flags |= (SD_BALANCE_WAKE|SD_BALANCE_NEWIDLE);
 981         }
 982 }
 983
 984 static void __sdt_free(const struct cpumask *cpu_map);
 985 static int __sdt_alloc(const struct cpumask *cpu_map);
 986
 987 static void __free_domain_allocs(struct s_data *d, enum s_alloc what,
 988                                  const struct cpumask *cpu_map)
 989 {
 990         switch (what) {
 991         case sa_rootdomain:
 992                 if (!atomic_read(&d->rd->refcount))
 993                         free_rootdomain(&d->rd->rcu);
 994                 /* Fall through */
 995         case sa_sd:
 996                 free_percpu(d->sd);
 997                 /* Fall through */
 998         case sa_sd_storage:
 999                 __sdt_free(cpu_map);
1000                 /* Fall through */
1001         case sa_none:
1002                 break;
1003         }
1004 }
1005
1006 static enum s_alloc
1007 __visit_domain_allocation_hell(struct s_data *d, const struct cpumask *cpu_map)
1008 {
1009         memset(d, 0, sizeof(*d));
1010
1011         if (__sdt_alloc(cpu_map))
1012                 return sa_sd_storage;
1013         d->sd = alloc_percpu(struct sched_domain *);
1014         if (!d->sd)
1015                 return sa_sd_storage;
1016         d->rd = alloc_rootdomain();
1017         if (!d->rd)
1018                 return sa_sd;
1019         return sa_rootdomain;
1020 }
1021
1022 /*
1023  * NULL the sd_data elements we've used to build the sched_domain and
1024  * sched_group structure so that the subsequent __free_domain_allocs()
1025  * will not free the data we're using.
1026  */
1027 static void claim_allocations(int cpu, struct sched_domain *sd)
1028 {
1029         struct sd_data *sdd = sd->private;
1030
1031         WARN_ON_ONCE(*per_cpu_ptr(sdd->sd, cpu) != sd);
1032         *per_cpu_ptr(sdd->sd, cpu) = NULL;
1033
1034         if (atomic_read(&(*per_cpu_ptr(sdd->sds, cpu))->ref))
1035                 *per_cpu_ptr(sdd->sds, cpu) = NULL;
1036
1037         if (atomic_read(&(*per_cpu_ptr(sdd->sg, cpu))->ref))
1038                 *per_cpu_ptr(sdd->sg, cpu) = NULL;
1039
1040         if (atomic_read(&(*per_cpu_ptr(sdd->sgc, cpu))->ref))
1041                 *per_cpu_ptr(sdd->sgc, cpu) = NULL;
1042 }
1043
1044 #ifdef CONFIG_NUMA
1045 static int sched_domains_numa_levels;
1046 enum numa_topology_type sched_numa_topology_type;
1047 static int *sched_domains_numa_distance;
1048 int sched_max_numa_distance;
1049 static struct cpumask ***sched_domains_numa_masks;
1050 static int sched_domains_curr_level;
1051 #endif
1052
1053 /*
1054  * SD_flags allowed in topology descriptions.
1055  *
1056  * These flags are purely descriptive of the topology and do not prescribe
1057  * behaviour. Behaviour is artificial and mapped in the below sd_init()
1058  * function:
1059  *
1060  *   SD_SHARE_CPUCAPACITY   - describes SMT topologies
1061  *   SD_SHARE_PKG_RESOURCES - describes shared caches
1062  *   SD_NUMA                - describes NUMA topologies
1063  *   SD_SHARE_POWERDOMAIN   - describes shared power domain
1064  *   SD_ASYM_CPUCAPACITY    - describes mixed capacity topologies
1065  *
1066  * Odd one out, which beside describing the topology has a quirk also
1067  * prescribes the desired behaviour that goes along with it:
1068  *
1069  *   SD_ASYM_PACKING        - describes SMT quirks
1070  */
1071 #define TOPOLOGY_SD_FLAGS               \
1072         (SD_SHARE_CPUCAPACITY |         \
1073          SD_SHARE_PKG_RESOURCES |       \
1074          SD_NUMA |                      \
1075          SD_ASYM_PACKING |              \
1076          SD_ASYM_CPUCAPACITY |          \
1077          SD_SHARE_POWERDOMAIN)
1078
1079 static struct sched_domain *
1080 sd_init(struct sched_domain_topology_level *tl,
1081         const struct cpumask *cpu_map,
1082         struct sched_domain *child, int cpu)
1083 {
1084         struct sd_data *sdd = &tl->data;
1085         struct sched_domain *sd = *per_cpu_ptr(sdd->sd, cpu);
1086         int sd_id, sd_weight, sd_flags = 0;
1087
1088 #ifdef CONFIG_NUMA
1089         /*
1090          * Ugly hack to pass state to sd_numa_mask()...
1091          */
1092         sched_domains_curr_level = tl->numa_level;
1093 #endif
1094
1095         sd_weight = cpumask_weight(tl->mask(cpu));
1096
1097         if (tl->sd_flags)
1098                 sd_flags = (*tl->sd_flags)();
1099         if (WARN_ONCE(sd_flags & ~TOPOLOGY_SD_FLAGS,
1100                         "wrong sd_flags in topology description\n"))
1101                 sd_flags &= ~TOPOLOGY_SD_FLAGS;
1102
1103         *sd = (struct sched_domain){
1104                 .min_interval           = sd_weight,
1105                 .max_interval           = 2*sd_weight,
1106                 .busy_factor            = 32,
1107                 .imbalance_pct          = 125,
1108
1109                 .cache_nice_tries       = 0,
1110                 .busy_idx               = 0,
1111                 .idle_idx               = 0,
1112                 .newidle_idx            = 0,
1113                 .wake_idx               = 0,
1114                 .forkexec_idx           = 0,
1115
1116                 .flags                  = 1*SD_LOAD_BALANCE
1117                                         | 1*SD_BALANCE_NEWIDLE
1118                                         | 1*SD_BALANCE_EXEC
1119                                         | 1*SD_BALANCE_FORK
1120                                         | 0*SD_BALANCE_WAKE
1121                                         | 1*SD_WAKE_AFFINE
1122                                         | 0*SD_SHARE_CPUCAPACITY
1123                                         | 0*SD_SHARE_PKG_RESOURCES
1124                                         | 0*SD_SERIALIZE
1125                                         | 0*SD_PREFER_SIBLING
1126                                         | 0*SD_NUMA
1127                                         | sd_flags
1128                                         ,
1129
1130                 .last_balance           = jiffies,
1131                 .balance_interval       = sd_weight,
1132                 .smt_gain               = 0,
1133                 .max_newidle_lb_cost    = 0,
1134                 .next_decay_max_lb_cost = jiffies,
1135                 .child                  = child,
1136 #ifdef CONFIG_SCHED_DEBUG
1137                 .name                   = tl->name,
1138 #endif
1139         };
1140
1141         cpumask_and(sched_domain_span(sd), cpu_map, tl->mask(cpu));
1142         sd_id = cpumask_first(sched_domain_span(sd));
1143
1144         /*
1145          * Convert topological properties into behaviour.
1146          */
1147
1148         if (sd->flags & SD_ASYM_CPUCAPACITY) {
1149                 struct sched_domain *t = sd;
1150
1151                 for_each_lower_domain(t)
1152                         t->flags |= SD_BALANCE_WAKE;
1153         }
1154
1155         if (sd->flags & SD_SHARE_CPUCAPACITY) {
1156                 sd->flags |= SD_PREFER_SIBLING;
1157                 sd->imbalance_pct = 110;
1158                 sd->smt_gain = 1178; /* ~15% */
1159
1160         } else if (sd->flags & SD_SHARE_PKG_RESOURCES) {
1161                 sd->imbalance_pct = 117;
1162                 sd->cache_nice_tries = 1;
1163                 sd->busy_idx = 2;
1164
1165 #ifdef CONFIG_NUMA
1166         } else if (sd->flags & SD_NUMA) {
1167                 sd->cache_nice_tries = 2;
1168                 sd->busy_idx = 3;
1169                 sd->idle_idx = 2;
1170
1171                 sd->flags |= SD_SERIALIZE;
1172                 if (sched_domains_numa_distance[tl->numa_level] > RECLAIM_DISTANCE) {
1173                         sd->flags &= ~(SD_BALANCE_EXEC |
1174                                        SD_BALANCE_FORK |
1175                                        SD_WAKE_AFFINE);
1176                 }
1177
1178 #endif
1179         } else {
1180                 sd->flags |= SD_PREFER_SIBLING;
1181                 sd->cache_nice_tries = 1;
1182                 sd->busy_idx = 2;
1183                 sd->idle_idx = 1;
1184         }
1185
1186         /*
1187          * For all levels sharing cache; connect a sched_domain_shared
1188          * instance.
1189          */
1190         if (sd->flags & SD_SHARE_PKG_RESOURCES) {
1191                 sd->shared = *per_cpu_ptr(sdd->sds, sd_id);
1192                 atomic_inc(&sd->shared->ref);
1193                 atomic_set(&sd->shared->nr_busy_cpus, sd_weight);
1194         }
1195
1196         sd->private = sdd;
1197
1198         return sd;
1199 }
1200
1201 /*
1202  * Topology list, bottom-up.
1203  */
1204 static struct sched_domain_topology_level default_topology[] = {
1205 #ifdef CONFIG_SCHED_SMT
1206         { cpu_smt_mask, cpu_smt_flags, SD_INIT_NAME(SMT) },
1207 #endif
1208 #ifdef CONFIG_SCHED_MC
1209         { cpu_coregroup_mask, cpu_core_flags, SD_INIT_NAME(MC) },
1210 #endif
1211         { cpu_cpu_mask, SD_INIT_NAME(DIE) },
1212         { NULL, },
1213 };
1214
1215 static struct sched_domain_topology_level *sched_domain_topology =
1216         default_topology;
1217
1218 #define for_each_sd_topology(tl)                        \
1219         for (tl = sched_domain_topology; tl->mask; tl++)
1220
1221 void set_sched_topology(struct sched_domain_topology_level *tl)
1222 {
1223         if (WARN_ON_ONCE(sched_smp_initialized))
1224                 return;
1225
1226         sched_domain_topology = tl;
1227 }
1228
1229 #ifdef CONFIG_NUMA
1230
1231 static const struct cpumask *sd_numa_mask(int cpu)
1232 {
1233         return sched_domains_numa_masks[sched_domains_curr_level][cpu_to_node(cpu)];
1234 }
1235
1236 static void sched_numa_warn(const char *str)
1237 {
1238         static int done = false;
1239         int i,j;
1240
1241         if (done)
1242                 return;
1243
1244         done = true;
1245
1246         printk(KERN_WARNING "ERROR: %s\n\n", str);
1247
1248         for (i = 0; i < nr_node_ids; i++) {
1249                 printk(KERN_WARNING "  ");
1250                 for (j = 0; j < nr_node_ids; j++)
1251                         printk(KERN_CONT "%02d ", node_distance(i,j));
1252                 printk(KERN_CONT "\n");
1253         }
1254         printk(KERN_WARNING "\n");
1255 }
1256
1257 bool find_numa_distance(int distance)
1258 {
1259         int i;
1260
1261         if (distance == node_distance(0, 0))
1262                 return true;
1263
1264         for (i = 0; i < sched_domains_numa_levels; i++) {
1265                 if (sched_domains_numa_distance[i] == distance)
1266                         return true;
1267         }
1268
1269         return false;
1270 }
1271
1272 /*
1273  * A system can have three types of NUMA topology:
1274  * NUMA_DIRECT: all nodes are directly connected, or not a NUMA system
1275  * NUMA_GLUELESS_MESH: some nodes reachable through intermediary nodes
1276  * NUMA_BACKPLANE: nodes can reach other nodes through a backplane
1277  *
1278  * The difference between a glueless mesh topology and a backplane
1279  * topology lies in whether communication between not directly
1280  * connected nodes goes through intermediary nodes (where programs
1281  * could run), or through backplane controllers. This affects
1282  * placement of programs.
1283  *
1284  * The type of topology can be discerned with the following tests:
1285  * - If the maximum distance between any nodes is 1 hop, the system
1286  *   is directly connected.
1287  * - If for two nodes A and B, located N > 1 hops away from each other,
1288  *   there is an intermediary node C, which is < N hops away from both
1289  *   nodes A and B, the system is a glueless mesh.
1290  */
1291 static void init_numa_topology_type(void)
1292 {
1293         int a, b, c, n;
1294
1295         n = sched_max_numa_distance;
1296
1297         if (sched_domains_numa_levels <= 1) {
1298                 sched_numa_topology_type = NUMA_DIRECT;
1299                 return;
1300         }
1301
1302         for_each_online_node(a) {
1303                 for_each_online_node(b) {
1304                         /* Find two nodes furthest removed from each other. */
1305                         if (node_distance(a, b) < n)
1306                                 continue;
1307
1308                         /* Is there an intermediary node between a and b? */
1309                         for_each_online_node(c) {
1310                                 if (node_distance(a, c) < n &&
1311                                     node_distance(b, c) < n) {
1312                                         sched_numa_topology_type =
1313                                                         NUMA_GLUELESS_MESH;
1314                                         return;
1315                                 }
1316                         }
1317
1318                         sched_numa_topology_type = NUMA_BACKPLANE;
1319                         return;
1320                 }
1321         }
1322 }
1323
1324 void sched_init_numa(void)
1325 {
1326         int next_distance, curr_distance = node_distance(0, 0);
1327         struct sched_domain_topology_level *tl;
1328         int level = 0;
1329         int i, j, k;
1330
1331         sched_domains_numa_distance = kzalloc(sizeof(int) * nr_node_ids, GFP_KERNEL);
1332         if (!sched_domains_numa_distance)
1333                 return;
1334
1335         /*
1336          * O(nr_nodes^2) deduplicating selection sort -- in order to find the
1337          * unique distances in the node_distance() table.
1338          *
1339          * Assumes node_distance(0,j) includes all distances in
1340          * node_distance(i,j) in order to avoid cubic time.
1341          */
1342         next_distance = curr_distance;
1343         for (i = 0; i < nr_node_ids; i++) {
1344                 for (j = 0; j < nr_node_ids; j++) {
1345                         for (k = 0; k < nr_node_ids; k++) {
1346                                 int distance = node_distance(i, k);
1347
1348                                 if (distance > curr_distance &&
1349                                     (distance < next_distance ||
1350                                      next_distance == curr_distance))
1351                                         next_distance = distance;
1352
1353                                 /*
1354                                  * While not a strong assumption it would be nice to know
1355                                  * about cases where if node A is connected to B, B is not
1356                                  * equally connected to A.
1357                                  */
1358                                 if (sched_debug() && node_distance(k, i) != distance)
1359                                         sched_numa_warn("Node-distance not symmetric");
1360
1361                                 if (sched_debug() && i && !find_numa_distance(distance))
1362                                         sched_numa_warn("Node-0 not representative");
1363                         }
1364                         if (next_distance != curr_distance) {
1365                                 sched_domains_numa_distance[level++] = next_distance;
1366                                 sched_domains_numa_levels = level;
1367                                 curr_distance = next_distance;
1368                         } else break;
1369                 }
1370
1371                 /*
1372                  * In case of sched_debug() we verify the above assumption.
1373                  */
1374                 if (!sched_debug())
1375                         break;
1376         }
1377
1378         if (!level)
1379                 return;
1380
1381         /*
1382          * 'level' contains the number of unique distances, excluding the
1383          * identity distance node_distance(i,i).
1384          *
1385          * The sched_domains_numa_distance[] array includes the actual distance
1386          * numbers.
1387          */
1388
1389         /*
1390          * Here, we should temporarily reset sched_domains_numa_levels to 0.
1391          * If it fails to allocate memory for array sched_domains_numa_masks[][],
1392          * the array will contain less then 'level' members. This could be
1393          * dangerous when we use it to iterate array sched_domains_numa_masks[][]
1394          * in other functions.
1395          *
1396          * We reset it to 'level' at the end of this function.
1397          */
1398         sched_domains_numa_levels = 0;
1399
1400         sched_domains_numa_masks = kzalloc(sizeof(void *) * level, GFP_KERNEL);
1401         if (!sched_domains_numa_masks)
1402                 return;
1403
1404         /*
1405          * Now for each level, construct a mask per node which contains all
1406          * CPUs of nodes that are that many hops away from us.
1407          */
1408         for (i = 0; i < level; i++) {
1409                 sched_domains_numa_masks[i] =
1410                         kzalloc(nr_node_ids * sizeof(void *), GFP_KERNEL);
1411                 if (!sched_domains_numa_masks[i])
1412                         return;
1413
1414                 for (j = 0; j < nr_node_ids; j++) {
1415                         struct cpumask *mask = kzalloc(cpumask_size(), GFP_KERNEL);
1416                         if (!mask)
1417                                 return;
1418
1419                         sched_domains_numa_masks[i][j] = mask;
1420
1421                         for_each_node(k) {
1422                                 if (node_distance(j, k) > sched_domains_numa_distance[i])
1423                                         continue;
1424
1425                                 cpumask_or(mask, mask, cpumask_of_node(k));
1426                         }
1427                 }
1428         }
1429
1430         /* Compute default topology size */
1431         for (i = 0; sched_domain_topology[i].mask; i++);
1432
1433         tl = kzalloc((i + level + 1) *
1434                         sizeof(struct sched_domain_topology_level), GFP_KERNEL);
1435         if (!tl)
1436                 return;
1437
1438         /*
1439          * Copy the default topology bits..
1440          */
1441         for (i = 0; sched_domain_topology[i].mask; i++)
1442                 tl[i] = sched_domain_topology[i];
1443
1444         /*
1445          * .. and append 'j' levels of NUMA goodness.
1446          */
1447         for (j = 0; j < level; i++, j++) {
1448                 tl[i] = (struct sched_domain_topology_level){
1449                         .mask = sd_numa_mask,
1450                         .sd_flags = cpu_numa_flags,
1451                         .flags = SDTL_OVERLAP,
1452                         .numa_level = j,
1453                         SD_INIT_NAME(NUMA)
1454                 };
1455         }
1456
1457         sched_domain_topology = tl;
1458
1459         sched_domains_numa_levels = level;
1460         sched_max_numa_distance = sched_domains_numa_distance[level - 1];
1461
1462         init_numa_topology_type();
1463 }
1464
1465 void sched_domains_numa_masks_set(unsigned int cpu)
1466 {
1467         int node = cpu_to_node(cpu);
1468         int i, j;
1469
1470         for (i = 0; i < sched_domains_numa_levels; i++) {
1471                 for (j = 0; j < nr_node_ids; j++) {
1472                         if (node_distance(j, node) <= sched_domains_numa_distance[i])
1473                                 cpumask_set_cpu(cpu, sched_domains_numa_masks[i][j]);
1474                 }
1475         }
1476 }
1477
1478 void sched_domains_numa_masks_clear(unsigned int cpu)
1479 {
1480         int i, j;
1481
1482         for (i = 0; i < sched_domains_numa_levels; i++) {
1483                 for (j = 0; j < nr_node_ids; j++)
1484                         cpumask_clear_cpu(cpu, sched_domains_numa_masks[i][j]);
1485         }
1486 }
1487
1488 #endif /* CONFIG_NUMA */
1489
1490 static int __sdt_alloc(const struct cpumask *cpu_map)
1491 {
1492         struct sched_domain_topology_level *tl;
1493         int j;
1494
1495         for_each_sd_topology(tl) {
1496                 struct sd_data *sdd = &tl->data;
1497
1498                 sdd->sd = alloc_percpu(struct sched_domain *);
1499                 if (!sdd->sd)
1500                         return -ENOMEM;
1501
1502                 sdd->sds = alloc_percpu(struct sched_domain_shared *);
1503                 if (!sdd->sds)
1504                         return -ENOMEM;
1505
1506                 sdd->sg = alloc_percpu(struct sched_group *);
1507                 if (!sdd->sg)
1508                         return -ENOMEM;
1509
1510                 sdd->sgc = alloc_percpu(struct sched_group_capacity *);
1511                 if (!sdd->sgc)
1512                         return -ENOMEM;
1513
1514                 for_each_cpu(j, cpu_map) {
1515                         struct sched_domain *sd;
1516                         struct sched_domain_shared *sds;
1517                         struct sched_group *sg;
1518                         struct sched_group_capacity *sgc;
1519
1520                         sd = kzalloc_node(sizeof(struct sched_domain) + cpumask_size(),
1521                                         GFP_KERNEL, cpu_to_node(j));
1522                         if (!sd)
1523                                 return -ENOMEM;
1524
1525                         *per_cpu_ptr(sdd->sd, j) = sd;
1526
1527                         sds = kzalloc_node(sizeof(struct sched_domain_shared),
1528                                         GFP_KERNEL, cpu_to_node(j));
1529                         if (!sds)
1530                                 return -ENOMEM;
1531
1532                         *per_cpu_ptr(sdd->sds, j) = sds;
1533
1534                         sg = kzalloc_node(sizeof(struct sched_group) + cpumask_size(),
1535                                         GFP_KERNEL, cpu_to_node(j));
1536                         if (!sg)
1537                                 return -ENOMEM;
1538
1539                         sg->next = sg;
1540
1541                         *per_cpu_ptr(sdd->sg, j) = sg;
1542
1543                         sgc = kzalloc_node(sizeof(struct sched_group_capacity) + cpumask_size(),
1544                                         GFP_KERNEL, cpu_to_node(j));
1545                         if (!sgc)
1546                                 return -ENOMEM;
1547
1548 #ifdef CONFIG_SCHED_DEBUG
1549                         sgc->id = j;
1550 #endif
1551
1552                         *per_cpu_ptr(sdd->sgc, j) = sgc;
1553                 }
1554         }
1555
1556         return 0;
1557 }
1558
1559 static void __sdt_free(const struct cpumask *cpu_map)
1560 {
1561         struct sched_domain_topology_level *tl;
1562         int j;
1563
1564         for_each_sd_topology(tl) {
1565                 struct sd_data *sdd = &tl->data;
1566
1567                 for_each_cpu(j, cpu_map) {
1568                         struct sched_domain *sd;
1569
1570                         if (sdd->sd) {
1571                                 sd = *per_cpu_ptr(sdd->sd, j);
1572                                 if (sd && (sd->flags & SD_OVERLAP))
1573                                         free_sched_groups(sd->groups, 0);
1574                                 kfree(*per_cpu_ptr(sdd->sd, j));
1575                         }
1576
1577                         if (sdd->sds)
1578                                 kfree(*per_cpu_ptr(sdd->sds, j));
1579                         if (sdd->sg)
1580                                 kfree(*per_cpu_ptr(sdd->sg, j));
1581                         if (sdd->sgc)
1582                                 kfree(*per_cpu_ptr(sdd->sgc, j));
1583                 }
1584                 free_percpu(sdd->sd);
1585                 sdd->sd = NULL;
1586                 free_percpu(sdd->sds);
1587                 sdd->sds = NULL;
1588                 free_percpu(sdd->sg);
1589                 sdd->sg = NULL;
1590                 free_percpu(sdd->sgc);
1591                 sdd->sgc = NULL;
1592         }
1593 }
1594
1595 static struct sched_domain *build_sched_domain(struct sched_domain_topology_level *tl,
1596                 const struct cpumask *cpu_map, struct sched_domain_attr *attr,
1597                 struct sched_domain *child, int cpu)
1598 {
1599         struct sched_domain *sd = sd_init(tl, cpu_map, child, cpu);
1600
1601         if (child) {
1602                 sd->level = child->level + 1;
1603                 sched_domain_level_max = max(sched_domain_level_max, sd->level);
1604                 child->parent = sd;
1605
1606                 if (!cpumask_subset(sched_domain_span(child),
1607                                     sched_domain_span(sd))) {
1608                         pr_err("BUG: arch topology borken\n");
1609 #ifdef CONFIG_SCHED_DEBUG
1610                         pr_err("     the %s domain not a subset of the %s domain\n",
1611                                         child->name, sd->name);
1612 #endif
1613                         /* Fixup, ensure @sd has at least @child cpus. */
1614                         cpumask_or(sched_domain_span(sd),
1615                                    sched_domain_span(sd),
1616                                    sched_domain_span(child));
1617                 }
1618
1619         }
1620         set_domain_attribute(sd, attr);
1621
1622         return sd;
1623 }
1624
1625 /*
1626  * Build sched domains for a given set of CPUs and attach the sched domains
1627  * to the individual CPUs
1628  */
1629 static int
1630 build_sched_domains(const struct cpumask *cpu_map, struct sched_domain_attr *attr)
1631 {
1632         enum s_alloc alloc_state;
1633         struct sched_domain *sd;
1634         struct s_data d;
1635         struct rq *rq = NULL;
1636         int i, ret = -ENOMEM;
1637
1638         alloc_state = __visit_domain_allocation_hell(&d, cpu_map);
1639         if (alloc_state != sa_rootdomain)
1640                 goto error;
1641
1642         /* Set up domains for CPUs specified by the cpu_map: */
1643         for_each_cpu(i, cpu_map) {
1644                 struct sched_domain_topology_level *tl;
1645
1646                 sd = NULL;
1647                 for_each_sd_topology(tl) {
1648                         sd = build_sched_domain(tl, cpu_map, attr, sd, i);
1649                         if (tl == sched_domain_topology)
1650                                 *per_cpu_ptr(d.sd, i) = sd;
1651                         if (tl->flags & SDTL_OVERLAP)
1652                                 sd->flags |= SD_OVERLAP;
1653                         if (cpumask_equal(cpu_map, sched_domain_span(sd)))
1654                                 break;
1655                 }
1656         }
1657
1658         /* Build the groups for the domains */
1659         for_each_cpu(i, cpu_map) {
1660                 for (sd = *per_cpu_ptr(d.sd, i); sd; sd = sd->parent) {
1661                         sd->span_weight = cpumask_weight(sched_domain_span(sd));
1662                         if (sd->flags & SD_OVERLAP) {
1663                                 if (build_overlap_sched_groups(sd, i))
1664                                         goto error;
1665                         } else {
1666                                 if (build_sched_groups(sd, i))
1667                                         goto error;
1668                         }
1669                 }
1670         }
1671
1672         /* Calculate CPU capacity for physical packages and nodes */
1673         for (i = nr_cpumask_bits-1; i >= 0; i--) {
1674                 if (!cpumask_test_cpu(i, cpu_map))
1675                         continue;
1676
1677                 for (sd = *per_cpu_ptr(d.sd, i); sd; sd = sd->parent) {
1678                         claim_allocations(i, sd);
1679                         init_sched_groups_capacity(i, sd);
1680                 }
1681         }
1682
1683         /* Attach the domains */
1684         rcu_read_lock();
1685         for_each_cpu(i, cpu_map) {
1686                 rq = cpu_rq(i);
1687                 sd = *per_cpu_ptr(d.sd, i);
1688
1689                 /* Use READ_ONCE()/WRITE_ONCE() to avoid load/store tearing: */
1690                 if (rq->cpu_capacity_orig > READ_ONCE(d.rd->max_cpu_capacity))
1691                         WRITE_ONCE(d.rd->max_cpu_capacity, rq->cpu_capacity_orig);
1692
1693                 cpu_attach_domain(sd, d.rd, i);
1694         }
1695         rcu_read_unlock();
1696
1697         if (rq && sched_debug_enabled) {
1698                 pr_info("span: %*pbl (max cpu_capacity = %lu)\n",
1699                         cpumask_pr_args(cpu_map), rq->rd->max_cpu_capacity);
1700         }
1701
1702         ret = 0;
1703 error:
1704         __free_domain_allocs(&d, alloc_state, cpu_map);
1705         return ret;
1706 }
1707
1708 /* Current sched domains: */
1709 static cpumask_var_t                    *doms_cur;
1710
1711 /* Number of sched domains in 'doms_cur': */
1712 static int                              ndoms_cur;
1713
1714 /* Attribues of custom domains in 'doms_cur' */
1715 static struct sched_domain_attr         *dattr_cur;
1716
1717 /*
1718  * Special case: If a kmalloc() of a doms_cur partition (array of
1719  * cpumask) fails, then fallback to a single sched domain,
1720  * as determined by the single cpumask fallback_doms.
1721  */
1722 static cpumask_var_t                    fallback_doms;
1723
1724 /*
1725  * arch_update_cpu_topology lets virtualized architectures update the
1726  * CPU core maps. It is supposed to return 1 if the topology changed
1727  * or 0 if it stayed the same.
1728  */
1729 int __weak arch_update_cpu_topology(void)
1730 {
1731         return 0;
1732 }
1733
1734 cpumask_var_t *alloc_sched_domains(unsigned int ndoms)
1735 {
1736         int i;
1737         cpumask_var_t *doms;
1738
1739         doms = kmalloc(sizeof(*doms) * ndoms, GFP_KERNEL);
1740         if (!doms)
1741                 return NULL;
1742         for (i = 0; i < ndoms; i++) {
1743                 if (!alloc_cpumask_var(&doms[i], GFP_KERNEL)) {
1744                         free_sched_domains(doms, i);
1745                         return NULL;
1746                 }
1747         }
1748         return doms;
1749 }
1750
1751 void free_sched_domains(cpumask_var_t doms[], unsigned int ndoms)
1752 {
1753         unsigned int i;
1754         for (i = 0; i < ndoms; i++)
1755                 free_cpumask_var(doms[i]);
1756         kfree(doms);
1757 }
1758
1759 /*
1760  * Set up scheduler domains and groups. Callers must hold the hotplug lock.
1761  * For now this just excludes isolated CPUs, but could be used to
1762  * exclude other special cases in the future.
1763  */
1764 int sched_init_domains(const struct cpumask *cpu_map)
1765 {
1766         int err;
1767
1768         zalloc_cpumask_var(&sched_domains_tmpmask, GFP_KERNEL);
1769         zalloc_cpumask_var(&sched_domains_tmpmask2, GFP_KERNEL);
1770         zalloc_cpumask_var(&fallback_doms, GFP_KERNEL);
1771
1772         arch_update_cpu_topology();
1773         ndoms_cur = 1;
1774         doms_cur = alloc_sched_domains(ndoms_cur);
1775         if (!doms_cur)
1776                 doms_cur = &fallback_doms;
1777         cpumask_andnot(doms_cur[0], cpu_map, cpu_isolated_map);
1778         err = build_sched_domains(doms_cur[0], NULL);
1779         register_sched_domain_sysctl();
1780
1781         return err;
1782 }
1783
1784 /*
1785  * Detach sched domains from a group of CPUs specified in cpu_map
1786  * These CPUs will now be attached to the NULL domain
1787  */
1788 static void detach_destroy_domains(const struct cpumask *cpu_map)
1789 {
1790         int i;
1791
1792         rcu_read_lock();
1793         for_each_cpu(i, cpu_map)
1794                 cpu_attach_domain(NULL, &def_root_domain, i);
1795         rcu_read_unlock();
1796 }
1797
1798 /* handle null as "default" */
1799 static int dattrs_equal(struct sched_domain_attr *cur, int idx_cur,
1800                         struct sched_domain_attr *new, int idx_new)
1801 {
1802         struct sched_domain_attr tmp;
1803
1804         /* Fast path: */
1805         if (!new && !cur)
1806                 return 1;
1807
1808         tmp = SD_ATTR_INIT;
1809         return !memcmp(cur ? (cur + idx_cur) : &tmp,
1810                         new ? (new + idx_new) : &tmp,
1811                         sizeof(struct sched_domain_attr));
1812 }
1813
1814 /*
1815  * Partition sched domains as specified by the 'ndoms_new'
1816  * cpumasks in the array doms_new[] of cpumasks. This compares
1817  * doms_new[] to the current sched domain partitioning, doms_cur[].
1818  * It destroys each deleted domain and builds each new domain.
1819  *
1820  * 'doms_new' is an array of cpumask_var_t's of length 'ndoms_new'.
1821  * The masks don't intersect (don't overlap.) We should setup one
1822  * sched domain for each mask. CPUs not in any of the cpumasks will
1823  * not be load balanced. If the same cpumask appears both in the
1824  * current 'doms_cur' domains and in the new 'doms_new', we can leave
1825  * it as it is.
1826  *
1827  * The passed in 'doms_new' should be allocated using
1828  * alloc_sched_domains.  This routine takes ownership of it and will
1829  * free_sched_domains it when done with it. If the caller failed the
1830  * alloc call, then it can pass in doms_new == NULL && ndoms_new == 1,
1831  * and partition_sched_domains() will fallback to the single partition
1832  * 'fallback_doms', it also forces the domains to be rebuilt.
1833  *
1834  * If doms_new == NULL it will be replaced with cpu_online_mask.
1835  * ndoms_new == 0 is a special case for destroying existing domains,
1836  * and it will not create the default domain.
1837  *
1838  * Call with hotplug lock held
1839  */
1840 void partition_sched_domains(int ndoms_new, cpumask_var_t doms_new[],
1841                              struct sched_domain_attr *dattr_new)
1842 {
1843         int i, j, n;
1844         int new_topology;
1845
1846         mutex_lock(&sched_domains_mutex);
1847
1848         /* Always unregister in case we don't destroy any domains: */
1849         unregister_sched_domain_sysctl();
1850
1851         /* Let the architecture update CPU core mappings: */
1852         new_topology = arch_update_cpu_topology();
1853
1854         if (!doms_new) {
1855                 WARN_ON_ONCE(dattr_new);
1856                 n = 0;
1857                 doms_new = alloc_sched_domains(1);
1858                 if (doms_new) {
1859                         n = 1;
1860                         cpumask_andnot(doms_new[0], cpu_active_mask, cpu_isolated_map);
1861                 }
1862         } else {
1863                 n = ndoms_new;
1864         }
1865
1866         /* Destroy deleted domains: */
1867         for (i = 0; i < ndoms_cur; i++) {
1868                 for (j = 0; j < n && !new_topology; j++) {
1869                         if (cpumask_equal(doms_cur[i], doms_new[j])
1870                             && dattrs_equal(dattr_cur, i, dattr_new, j))
1871                                 goto match1;
1872                 }
1873                 /* No match - a current sched domain not in new doms_new[] */
1874                 detach_destroy_domains(doms_cur[i]);
1875 match1:
1876                 ;
1877         }
1878
1879         n = ndoms_cur;
1880         if (!doms_new) {
1881                 n = 0;
1882                 doms_new = &fallback_doms;
1883                 cpumask_andnot(doms_new[0], cpu_active_mask, cpu_isolated_map);
1884         }
1885
1886         /* Build new domains: */
1887         for (i = 0; i < ndoms_new; i++) {
1888                 for (j = 0; j < n && !new_topology; j++) {
1889                         if (cpumask_equal(doms_new[i], doms_cur[j])
1890                             && dattrs_equal(dattr_new, i, dattr_cur, j))
1891                                 goto match2;
1892                 }
1893                 /* No match - add a new doms_new */
1894                 build_sched_domains(doms_new[i], dattr_new ? dattr_new + i : NULL);
1895 match2:
1896                 ;
1897         }
1898
1899         /* Remember the new sched domains: */
1900         if (doms_cur != &fallback_doms)
1901                 free_sched_domains(doms_cur, ndoms_cur);
1902
1903         kfree(dattr_cur);
1904         doms_cur = doms_new;
1905         dattr_cur = dattr_new;
1906         ndoms_cur = ndoms_new;
1907
1908         register_sched_domain_sysctl();
1909
1910         mutex_unlock(&sched_domains_mutex);
1911 }
1912