kernel/sched/topology.c

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