linux/kernel/sched/topology.c
<<
>>
Prefs
   1// SPDX-License-Identifier: GPL-2.0
   2/*
   3 * Scheduler topology setup/handling methods
   4 */
   5#include "sched.h"
   6
   7DEFINE_MUTEX(sched_domains_mutex);
   8
   9/* Protected by sched_domains_mutex: */
  10static cpumask_var_t sched_domains_tmpmask;
  11static cpumask_var_t sched_domains_tmpmask2;
  12
  13#ifdef CONFIG_SCHED_DEBUG
  14
  15static int __init sched_debug_setup(char *str)
  16{
  17        sched_debug_verbose = true;
  18
  19        return 0;
  20}
  21early_param("sched_verbose", sched_debug_setup);
  22
  23static inline bool sched_debug(void)
  24{
  25        return sched_debug_verbose;
  26}
  27
  28#define SD_FLAG(_name, mflags) [__##_name] = { .meta_flags = mflags, .name = #_name },
  29const struct sd_flag_debug sd_flag_debug[] = {
  30#include <linux/sched/sd_flags.h>
  31};
  32#undef SD_FLAG
  33
  34static int sched_domain_debug_one(struct sched_domain *sd, int cpu, int level,
  35                                  struct cpumask *groupmask)
  36{
  37        struct sched_group *group = sd->groups;
  38        unsigned long flags = sd->flags;
  39        unsigned int idx;
  40
  41        cpumask_clear(groupmask);
  42
  43        printk(KERN_DEBUG "%*s domain-%d: ", level, "", level);
  44        printk(KERN_CONT "span=%*pbl level=%s\n",
  45               cpumask_pr_args(sched_domain_span(sd)), sd->name);
  46
  47        if (!cpumask_test_cpu(cpu, sched_domain_span(sd))) {
  48                printk(KERN_ERR "ERROR: domain->span does not contain CPU%d\n", cpu);
  49        }
  50        if (group && !cpumask_test_cpu(cpu, sched_group_span(group))) {
  51                printk(KERN_ERR "ERROR: domain->groups does not contain CPU%d\n", cpu);
  52        }
  53
  54        for_each_set_bit(idx, &flags, __SD_FLAG_CNT) {
  55                unsigned int flag = BIT(idx);
  56                unsigned int meta_flags = sd_flag_debug[idx].meta_flags;
  57
  58                if ((meta_flags & SDF_SHARED_CHILD) && sd->child &&
  59                    !(sd->child->flags & flag))
  60                        printk(KERN_ERR "ERROR: flag %s set here but not in child\n",
  61                               sd_flag_debug[idx].name);
  62
  63                if ((meta_flags & SDF_SHARED_PARENT) && sd->parent &&
  64                    !(sd->parent->flags & flag))
  65                        printk(KERN_ERR "ERROR: flag %s set here but not in parent\n",
  66                               sd_flag_debug[idx].name);
  67        }
  68
  69        printk(KERN_DEBUG "%*s groups:", level + 1, "");
  70        do {
  71                if (!group) {
  72                        printk("\n");
  73                        printk(KERN_ERR "ERROR: group is NULL\n");
  74                        break;
  75                }
  76
  77                if (!cpumask_weight(sched_group_span(group))) {
  78                        printk(KERN_CONT "\n");
  79                        printk(KERN_ERR "ERROR: empty group\n");
  80                        break;
  81                }
  82
  83                if (!(sd->flags & SD_OVERLAP) &&
  84                    cpumask_intersects(groupmask, sched_group_span(group))) {
  85                        printk(KERN_CONT "\n");
  86                        printk(KERN_ERR "ERROR: repeated CPUs\n");
  87                        break;
  88                }
  89
  90                cpumask_or(groupmask, groupmask, sched_group_span(group));
  91
  92                printk(KERN_CONT " %d:{ span=%*pbl",
  93                                group->sgc->id,
  94                                cpumask_pr_args(sched_group_span(group)));
  95
  96                if ((sd->flags & SD_OVERLAP) &&
  97                    !cpumask_equal(group_balance_mask(group), sched_group_span(group))) {
  98                        printk(KERN_CONT " mask=%*pbl",
  99                                cpumask_pr_args(group_balance_mask(group)));
 100                }
 101
 102                if (group->sgc->capacity != SCHED_CAPACITY_SCALE)
 103                        printk(KERN_CONT " cap=%lu", group->sgc->capacity);
 104
 105                if (group == sd->groups && sd->child &&
 106                    !cpumask_equal(sched_domain_span(sd->child),
 107                                   sched_group_span(group))) {
 108                        printk(KERN_ERR "ERROR: domain->groups does not match domain->child\n");
 109                }
 110
 111                printk(KERN_CONT " }");
 112
 113                group = group->next;
 114
 115                if (group != sd->groups)
 116                        printk(KERN_CONT ",");
 117
 118        } while (group != sd->groups);
 119        printk(KERN_CONT "\n");
 120
 121        if (!cpumask_equal(sched_domain_span(sd), groupmask))
 122                printk(KERN_ERR "ERROR: groups don't span domain->span\n");
 123
 124        if (sd->parent &&
 125            !cpumask_subset(groupmask, sched_domain_span(sd->parent)))
 126                printk(KERN_ERR "ERROR: parent span is not a superset of domain->span\n");
 127        return 0;
 128}
 129
 130static void sched_domain_debug(struct sched_domain *sd, int cpu)
 131{
 132        int level = 0;
 133
 134        if (!sched_debug_verbose)
 135                return;
 136
 137        if (!sd) {
 138                printk(KERN_DEBUG "CPU%d attaching NULL sched-domain.\n", cpu);
 139                return;
 140        }
 141
 142        printk(KERN_DEBUG "CPU%d attaching sched-domain(s):\n", cpu);
 143
 144        for (;;) {
 145                if (sched_domain_debug_one(sd, cpu, level, sched_domains_tmpmask))
 146                        break;
 147                level++;
 148                sd = sd->parent;
 149                if (!sd)
 150                        break;
 151        }
 152}
 153#else /* !CONFIG_SCHED_DEBUG */
 154
 155# define sched_debug_verbose 0
 156# define sched_domain_debug(sd, cpu) do { } while (0)
 157static inline bool sched_debug(void)
 158{
 159        return false;
 160}
 161#endif /* CONFIG_SCHED_DEBUG */
 162
 163/* Generate a mask of SD flags with the SDF_NEEDS_GROUPS metaflag */
 164#define SD_FLAG(name, mflags) (name * !!((mflags) & SDF_NEEDS_GROUPS)) |
 165static const unsigned int SD_DEGENERATE_GROUPS_MASK =
 166#include <linux/sched/sd_flags.h>
 1670;
 168#undef SD_FLAG
 169
 170static int sd_degenerate(struct sched_domain *sd)
 171{
 172        if (cpumask_weight(sched_domain_span(sd)) == 1)
 173                return 1;
 174
 175        /* Following flags need at least 2 groups */
 176        if ((sd->flags & SD_DEGENERATE_GROUPS_MASK) &&
 177            (sd->groups != sd->groups->next))
 178                return 0;
 179
 180        /* Following flags don't use groups */
 181        if (sd->flags & (SD_WAKE_AFFINE))
 182                return 0;
 183
 184        return 1;
 185}
 186
 187static int
 188sd_parent_degenerate(struct sched_domain *sd, struct sched_domain *parent)
 189{
 190        unsigned long cflags = sd->flags, pflags = parent->flags;
 191
 192        if (sd_degenerate(parent))
 193                return 1;
 194
 195        if (!cpumask_equal(sched_domain_span(sd), sched_domain_span(parent)))
 196                return 0;
 197
 198        /* Flags needing groups don't count if only 1 group in parent */
 199        if (parent->groups == parent->groups->next)
 200                pflags &= ~SD_DEGENERATE_GROUPS_MASK;
 201
 202        if (~cflags & pflags)
 203                return 0;
 204
 205        return 1;
 206}
 207
 208#if defined(CONFIG_ENERGY_MODEL) && defined(CONFIG_CPU_FREQ_GOV_SCHEDUTIL)
 209DEFINE_STATIC_KEY_FALSE(sched_energy_present);
 210unsigned int sysctl_sched_energy_aware = 1;
 211DEFINE_MUTEX(sched_energy_mutex);
 212bool sched_energy_update;
 213
 214void rebuild_sched_domains_energy(void)
 215{
 216        mutex_lock(&sched_energy_mutex);
 217        sched_energy_update = true;
 218        rebuild_sched_domains();
 219        sched_energy_update = false;
 220        mutex_unlock(&sched_energy_mutex);
 221}
 222
 223#ifdef CONFIG_PROC_SYSCTL
 224int sched_energy_aware_handler(struct ctl_table *table, int write,
 225                void *buffer, size_t *lenp, loff_t *ppos)
 226{
 227        int ret, state;
 228
 229        if (write && !capable(CAP_SYS_ADMIN))
 230                return -EPERM;
 231
 232        ret = proc_dointvec_minmax(table, write, buffer, lenp, ppos);
 233        if (!ret && write) {
 234                state = static_branch_unlikely(&sched_energy_present);
 235                if (state != sysctl_sched_energy_aware)
 236                        rebuild_sched_domains_energy();
 237        }
 238
 239        return ret;
 240}
 241#endif
 242
 243static void free_pd(struct perf_domain *pd)
 244{
 245        struct perf_domain *tmp;
 246
 247        while (pd) {
 248                tmp = pd->next;
 249                kfree(pd);
 250                pd = tmp;
 251        }
 252}
 253
 254static struct perf_domain *find_pd(struct perf_domain *pd, int cpu)
 255{
 256        while (pd) {
 257                if (cpumask_test_cpu(cpu, perf_domain_span(pd)))
 258                        return pd;
 259                pd = pd->next;
 260        }
 261
 262        return NULL;
 263}
 264
 265static struct perf_domain *pd_init(int cpu)
 266{
 267        struct em_perf_domain *obj = em_cpu_get(cpu);
 268        struct perf_domain *pd;
 269
 270        if (!obj) {
 271                if (sched_debug())
 272                        pr_info("%s: no EM found for CPU%d\n", __func__, cpu);
 273                return NULL;
 274        }
 275
 276        pd = kzalloc(sizeof(*pd), GFP_KERNEL);
 277        if (!pd)
 278                return NULL;
 279        pd->em_pd = obj;
 280
 281        return pd;
 282}
 283
 284static void perf_domain_debug(const struct cpumask *cpu_map,
 285                                                struct perf_domain *pd)
 286{
 287        if (!sched_debug() || !pd)
 288                return;
 289
 290        printk(KERN_DEBUG "root_domain %*pbl:", cpumask_pr_args(cpu_map));
 291
 292        while (pd) {
 293                printk(KERN_CONT " pd%d:{ cpus=%*pbl nr_pstate=%d }",
 294                                cpumask_first(perf_domain_span(pd)),
 295                                cpumask_pr_args(perf_domain_span(pd)),
 296                                em_pd_nr_perf_states(pd->em_pd));
 297                pd = pd->next;
 298        }
 299
 300        printk(KERN_CONT "\n");
 301}
 302
 303static void destroy_perf_domain_rcu(struct rcu_head *rp)
 304{
 305        struct perf_domain *pd;
 306
 307        pd = container_of(rp, struct perf_domain, rcu);
 308        free_pd(pd);
 309}
 310
 311static void sched_energy_set(bool has_eas)
 312{
 313        if (!has_eas && static_branch_unlikely(&sched_energy_present)) {
 314                if (sched_debug())
 315                        pr_info("%s: stopping EAS\n", __func__);
 316                static_branch_disable_cpuslocked(&sched_energy_present);
 317        } else if (has_eas && !static_branch_unlikely(&sched_energy_present)) {
 318                if (sched_debug())
 319                        pr_info("%s: starting EAS\n", __func__);
 320                static_branch_enable_cpuslocked(&sched_energy_present);
 321        }
 322}
 323
 324/*
 325 * EAS can be used on a root domain if it meets all the following conditions:
 326 *    1. an Energy Model (EM) is available;
 327 *    2. the SD_ASYM_CPUCAPACITY flag is set in the sched_domain hierarchy.
 328 *    3. no SMT is detected.
 329 *    4. the EM complexity is low enough to keep scheduling overheads low;
 330 *    5. schedutil is driving the frequency of all CPUs of the rd;
 331 *    6. frequency invariance support is present;
 332 *
 333 * The complexity of the Energy Model is defined as:
 334 *
 335 *              C = nr_pd * (nr_cpus + nr_ps)
 336 *
 337 * with parameters defined as:
 338 *  - nr_pd:    the number of performance domains
 339 *  - nr_cpus:  the number of CPUs
 340 *  - nr_ps:    the sum of the number of performance states of all performance
 341 *              domains (for example, on a system with 2 performance domains,
 342 *              with 10 performance states each, nr_ps = 2 * 10 = 20).
 343 *
 344 * It is generally not a good idea to use such a model in the wake-up path on
 345 * very complex platforms because of the associated scheduling overheads. The
 346 * arbitrary constraint below prevents that. It makes EAS usable up to 16 CPUs
 347 * with per-CPU DVFS and less than 8 performance states each, for example.
 348 */
 349#define EM_MAX_COMPLEXITY 2048
 350
 351extern struct cpufreq_governor schedutil_gov;
 352static bool build_perf_domains(const struct cpumask *cpu_map)
 353{
 354        int i, nr_pd = 0, nr_ps = 0, nr_cpus = cpumask_weight(cpu_map);
 355        struct perf_domain *pd = NULL, *tmp;
 356        int cpu = cpumask_first(cpu_map);
 357        struct root_domain *rd = cpu_rq(cpu)->rd;
 358        struct cpufreq_policy *policy;
 359        struct cpufreq_governor *gov;
 360
 361        if (!sysctl_sched_energy_aware)
 362                goto free;
 363
 364        /* EAS is enabled for asymmetric CPU capacity topologies. */
 365        if (!per_cpu(sd_asym_cpucapacity, cpu)) {
 366                if (sched_debug()) {
 367                        pr_info("rd %*pbl: CPUs do not have asymmetric capacities\n",
 368                                        cpumask_pr_args(cpu_map));
 369                }
 370                goto free;
 371        }
 372
 373        /* EAS definitely does *not* handle SMT */
 374        if (sched_smt_active()) {
 375                pr_warn("rd %*pbl: Disabling EAS, SMT is not supported\n",
 376                        cpumask_pr_args(cpu_map));
 377                goto free;
 378        }
 379
 380        if (!arch_scale_freq_invariant()) {
 381                if (sched_debug()) {
 382                        pr_warn("rd %*pbl: Disabling EAS: frequency-invariant load tracking not yet supported",
 383                                cpumask_pr_args(cpu_map));
 384                }
 385                goto free;
 386        }
 387
 388        for_each_cpu(i, cpu_map) {
 389                /* Skip already covered CPUs. */
 390                if (find_pd(pd, i))
 391                        continue;
 392
 393                /* Do not attempt EAS if schedutil is not being used. */
 394                policy = cpufreq_cpu_get(i);
 395                if (!policy)
 396                        goto free;
 397                gov = policy->governor;
 398                cpufreq_cpu_put(policy);
 399                if (gov != &schedutil_gov) {
 400                        if (rd->pd)
 401                                pr_warn("rd %*pbl: Disabling EAS, schedutil is mandatory\n",
 402                                                cpumask_pr_args(cpu_map));
 403                        goto free;
 404                }
 405
 406                /* Create the new pd and add it to the local list. */
 407                tmp = pd_init(i);
 408                if (!tmp)
 409                        goto free;
 410                tmp->next = pd;
 411                pd = tmp;
 412
 413                /*
 414                 * Count performance domains and performance states for the
 415                 * complexity check.
 416                 */
 417                nr_pd++;
 418                nr_ps += em_pd_nr_perf_states(pd->em_pd);
 419        }
 420
 421        /* Bail out if the Energy Model complexity is too high. */
 422        if (nr_pd * (nr_ps + nr_cpus) > EM_MAX_COMPLEXITY) {
 423                WARN(1, "rd %*pbl: Failed to start EAS, EM complexity is too high\n",
 424                                                cpumask_pr_args(cpu_map));
 425                goto free;
 426        }
 427
 428        perf_domain_debug(cpu_map, pd);
 429
 430        /* Attach the new list of performance domains to the root domain. */
 431        tmp = rd->pd;
 432        rcu_assign_pointer(rd->pd, pd);
 433        if (tmp)
 434                call_rcu(&tmp->rcu, destroy_perf_domain_rcu);
 435
 436        return !!pd;
 437
 438free:
 439        free_pd(pd);
 440        tmp = rd->pd;
 441        rcu_assign_pointer(rd->pd, NULL);
 442        if (tmp)
 443                call_rcu(&tmp->rcu, destroy_perf_domain_rcu);
 444
 445        return false;
 446}
 447#else
 448static void free_pd(struct perf_domain *pd) { }
 449#endif /* CONFIG_ENERGY_MODEL && CONFIG_CPU_FREQ_GOV_SCHEDUTIL*/
 450
 451static void free_rootdomain(struct rcu_head *rcu)
 452{
 453        struct root_domain *rd = container_of(rcu, struct root_domain, rcu);
 454
 455        cpupri_cleanup(&rd->cpupri);
 456        cpudl_cleanup(&rd->cpudl);
 457        free_cpumask_var(rd->dlo_mask);
 458        free_cpumask_var(rd->rto_mask);
 459        free_cpumask_var(rd->online);
 460        free_cpumask_var(rd->span);
 461        free_pd(rd->pd);
 462        kfree(rd);
 463}
 464
 465void rq_attach_root(struct rq *rq, struct root_domain *rd)
 466{
 467        struct root_domain *old_rd = NULL;
 468        unsigned long flags;
 469
 470        raw_spin_rq_lock_irqsave(rq, flags);
 471
 472        if (rq->rd) {
 473                old_rd = rq->rd;
 474
 475                if (cpumask_test_cpu(rq->cpu, old_rd->online))
 476                        set_rq_offline(rq);
 477
 478                cpumask_clear_cpu(rq->cpu, old_rd->span);
 479
 480                /*
 481                 * If we dont want to free the old_rd yet then
 482                 * set old_rd to NULL to skip the freeing later
 483                 * in this function:
 484                 */
 485                if (!atomic_dec_and_test(&old_rd->refcount))
 486                        old_rd = NULL;
 487        }
 488
 489        atomic_inc(&rd->refcount);
 490        rq->rd = rd;
 491
 492        cpumask_set_cpu(rq->cpu, rd->span);
 493        if (cpumask_test_cpu(rq->cpu, cpu_active_mask))
 494                set_rq_online(rq);
 495
 496        raw_spin_rq_unlock_irqrestore(rq, flags);
 497
 498        if (old_rd)
 499                call_rcu(&old_rd->rcu, free_rootdomain);
 500}
 501
 502void sched_get_rd(struct root_domain *rd)
 503{
 504        atomic_inc(&rd->refcount);
 505}
 506
 507void sched_put_rd(struct root_domain *rd)
 508{
 509        if (!atomic_dec_and_test(&rd->refcount))
 510                return;
 511
 512        call_rcu(&rd->rcu, free_rootdomain);
 513}
 514
 515static int init_rootdomain(struct root_domain *rd)
 516{
 517        if (!zalloc_cpumask_var(&rd->span, GFP_KERNEL))
 518                goto out;
 519        if (!zalloc_cpumask_var(&rd->online, GFP_KERNEL))
 520                goto free_span;
 521        if (!zalloc_cpumask_var(&rd->dlo_mask, GFP_KERNEL))
 522                goto free_online;
 523        if (!zalloc_cpumask_var(&rd->rto_mask, GFP_KERNEL))
 524                goto free_dlo_mask;
 525
 526#ifdef HAVE_RT_PUSH_IPI
 527        rd->rto_cpu = -1;
 528        raw_spin_lock_init(&rd->rto_lock);
 529        init_irq_work(&rd->rto_push_work, rto_push_irq_work_func);
 530#endif
 531
 532        rd->visit_gen = 0;
 533        init_dl_bw(&rd->dl_bw);
 534        if (cpudl_init(&rd->cpudl) != 0)
 535                goto free_rto_mask;
 536
 537        if (cpupri_init(&rd->cpupri) != 0)
 538                goto free_cpudl;
 539        return 0;
 540
 541free_cpudl:
 542        cpudl_cleanup(&rd->cpudl);
 543free_rto_mask:
 544        free_cpumask_var(rd->rto_mask);
 545free_dlo_mask:
 546        free_cpumask_var(rd->dlo_mask);
 547free_online:
 548        free_cpumask_var(rd->online);
 549free_span:
 550        free_cpumask_var(rd->span);
 551out:
 552        return -ENOMEM;
 553}
 554
 555/*
 556 * By default the system creates a single root-domain with all CPUs as
 557 * members (mimicking the global state we have today).
 558 */
 559struct root_domain def_root_domain;
 560
 561void init_defrootdomain(void)
 562{
 563        init_rootdomain(&def_root_domain);
 564
 565        atomic_set(&def_root_domain.refcount, 1);
 566}
 567
 568static struct root_domain *alloc_rootdomain(void)
 569{
 570        struct root_domain *rd;
 571
 572        rd = kzalloc(sizeof(*rd), GFP_KERNEL);
 573        if (!rd)
 574                return NULL;
 575
 576        if (init_rootdomain(rd) != 0) {
 577                kfree(rd);
 578                return NULL;
 579        }
 580
 581        return rd;
 582}
 583
 584static void free_sched_groups(struct sched_group *sg, int free_sgc)
 585{
 586        struct sched_group *tmp, *first;
 587
 588        if (!sg)
 589                return;
 590
 591        first = sg;
 592        do {
 593                tmp = sg->next;
 594
 595                if (free_sgc && atomic_dec_and_test(&sg->sgc->ref))
 596                        kfree(sg->sgc);
 597
 598                if (atomic_dec_and_test(&sg->ref))
 599                        kfree(sg);
 600                sg = tmp;
 601        } while (sg != first);
 602}
 603
 604static void destroy_sched_domain(struct sched_domain *sd)
 605{
 606        /*
 607         * A normal sched domain may have multiple group references, an
 608         * overlapping domain, having private groups, only one.  Iterate,
 609         * dropping group/capacity references, freeing where none remain.
 610         */
 611        free_sched_groups(sd->groups, 1);
 612
 613        if (sd->shared && atomic_dec_and_test(&sd->shared->ref))
 614                kfree(sd->shared);
 615        kfree(sd);
 616}
 617
 618static void destroy_sched_domains_rcu(struct rcu_head *rcu)
 619{
 620        struct sched_domain *sd = container_of(rcu, struct sched_domain, rcu);
 621
 622        while (sd) {
 623                struct sched_domain *parent = sd->parent;
 624                destroy_sched_domain(sd);
 625                sd = parent;
 626        }
 627}
 628
 629static void destroy_sched_domains(struct sched_domain *sd)
 630{
 631        if (sd)
 632                call_rcu(&sd->rcu, destroy_sched_domains_rcu);
 633}
 634
 635/*
 636 * Keep a special pointer to the highest sched_domain that has
 637 * SD_SHARE_PKG_RESOURCE set (Last Level Cache Domain) for this
 638 * allows us to avoid some pointer chasing select_idle_sibling().
 639 *
 640 * Also keep a unique ID per domain (we use the first CPU number in
 641 * the cpumask of the domain), this allows us to quickly tell if
 642 * two CPUs are in the same cache domain, see cpus_share_cache().
 643 */
 644DEFINE_PER_CPU(struct sched_domain __rcu *, sd_llc);
 645DEFINE_PER_CPU(int, sd_llc_size);
 646DEFINE_PER_CPU(int, sd_llc_id);
 647DEFINE_PER_CPU(struct sched_domain_shared __rcu *, sd_llc_shared);
 648DEFINE_PER_CPU(struct sched_domain __rcu *, sd_numa);
 649DEFINE_PER_CPU(struct sched_domain __rcu *, sd_asym_packing);
 650DEFINE_PER_CPU(struct sched_domain __rcu *, sd_asym_cpucapacity);
 651DEFINE_STATIC_KEY_FALSE(sched_asym_cpucapacity);
 652
 653static void update_top_cache_domain(int cpu)
 654{
 655        struct sched_domain_shared *sds = NULL;
 656        struct sched_domain *sd;
 657        int id = cpu;
 658        int size = 1;
 659
 660        sd = highest_flag_domain(cpu, SD_SHARE_PKG_RESOURCES);
 661        if (sd) {
 662                id = cpumask_first(sched_domain_span(sd));
 663                size = cpumask_weight(sched_domain_span(sd));
 664                sds = sd->shared;
 665        }
 666
 667        rcu_assign_pointer(per_cpu(sd_llc, cpu), sd);
 668        per_cpu(sd_llc_size, cpu) = size;
 669        per_cpu(sd_llc_id, cpu) = id;
 670        rcu_assign_pointer(per_cpu(sd_llc_shared, cpu), sds);
 671
 672        sd = lowest_flag_domain(cpu, SD_NUMA);
 673        rcu_assign_pointer(per_cpu(sd_numa, cpu), sd);
 674
 675        sd = highest_flag_domain(cpu, SD_ASYM_PACKING);
 676        rcu_assign_pointer(per_cpu(sd_asym_packing, cpu), sd);
 677
 678        sd = lowest_flag_domain(cpu, SD_ASYM_CPUCAPACITY_FULL);
 679        rcu_assign_pointer(per_cpu(sd_asym_cpucapacity, cpu), sd);
 680}
 681
 682/*
 683 * Attach the domain 'sd' to 'cpu' as its base domain. Callers must
 684 * hold the hotplug lock.
 685 */
 686static void
 687cpu_attach_domain(struct sched_domain *sd, struct root_domain *rd, int cpu)
 688{
 689        struct rq *rq = cpu_rq(cpu);
 690        struct sched_domain *tmp;
 691        int numa_distance = 0;
 692
 693        /* Remove the sched domains which do not contribute to scheduling. */
 694        for (tmp = sd; tmp; ) {
 695                struct sched_domain *parent = tmp->parent;
 696                if (!parent)
 697                        break;
 698
 699                if (sd_parent_degenerate(tmp, parent)) {
 700                        tmp->parent = parent->parent;
 701                        if (parent->parent)
 702                                parent->parent->child = tmp;
 703                        /*
 704                         * Transfer SD_PREFER_SIBLING down in case of a
 705                         * degenerate parent; the spans match for this
 706                         * so the property transfers.
 707                         */
 708                        if (parent->flags & SD_PREFER_SIBLING)
 709                                tmp->flags |= SD_PREFER_SIBLING;
 710                        destroy_sched_domain(parent);
 711                } else
 712                        tmp = tmp->parent;
 713        }
 714
 715        if (sd && sd_degenerate(sd)) {
 716                tmp = sd;
 717                sd = sd->parent;
 718                destroy_sched_domain(tmp);
 719                if (sd)
 720                        sd->child = NULL;
 721        }
 722
 723        for (tmp = sd; tmp; tmp = tmp->parent)
 724                numa_distance += !!(tmp->flags & SD_NUMA);
 725
 726        sched_domain_debug(sd, cpu);
 727
 728        rq_attach_root(rq, rd);
 729        tmp = rq->sd;
 730        rcu_assign_pointer(rq->sd, sd);
 731        dirty_sched_domain_sysctl(cpu);
 732        destroy_sched_domains(tmp);
 733
 734        update_top_cache_domain(cpu);
 735}
 736
 737struct s_data {
 738        struct sched_domain * __percpu *sd;
 739        struct root_domain      *rd;
 740};
 741
 742enum s_alloc {
 743        sa_rootdomain,
 744        sa_sd,
 745        sa_sd_storage,
 746        sa_none,
 747};
 748
 749/*
 750 * Return the canonical balance CPU for this group, this is the first CPU
 751 * of this group that's also in the balance mask.
 752 *
 753 * The balance mask are all those CPUs that could actually end up at this
 754 * group. See build_balance_mask().
 755 *
 756 * Also see should_we_balance().
 757 */
 758int group_balance_cpu(struct sched_group *sg)
 759{
 760        return cpumask_first(group_balance_mask(sg));
 761}
 762
 763
 764/*
 765 * NUMA topology (first read the regular topology blurb below)
 766 *
 767 * Given a node-distance table, for example:
 768 *
 769 *   node   0   1   2   3
 770 *     0:  10  20  30  20
 771 *     1:  20  10  20  30
 772 *     2:  30  20  10  20
 773 *     3:  20  30  20  10
 774 *
 775 * which represents a 4 node ring topology like:
 776 *
 777 *   0 ----- 1
 778 *   |       |
 779 *   |       |
 780 *   |       |
 781 *   3 ----- 2
 782 *
 783 * We want to construct domains and groups to represent this. The way we go
 784 * about doing this is to build the domains on 'hops'. For each NUMA level we
 785 * construct the mask of all nodes reachable in @level hops.
 786 *
 787 * For the above NUMA topology that gives 3 levels:
 788 *
 789 * NUMA-2       0-3             0-3             0-3             0-3
 790 *  groups:     {0-1,3},{1-3}   {0-2},{0,2-3}   {1-3},{0-1,3}   {0,2-3},{0-2}
 791 *
 792 * NUMA-1       0-1,3           0-2             1-3             0,2-3
 793 *  groups:     {0},{1},{3}     {0},{1},{2}     {1},{2},{3}     {0},{2},{3}
 794 *
 795 * NUMA-0       0               1               2               3
 796 *
 797 *
 798 * As can be seen; things don't nicely line up as with the regular topology.
 799 * When we iterate a domain in child domain chunks some nodes can be
 800 * represented multiple times -- hence the "overlap" naming for this part of
 801 * the topology.
 802 *
 803 * In order to minimize this overlap, we only build enough groups to cover the
 804 * domain. For instance Node-0 NUMA-2 would only get groups: 0-1,3 and 1-3.
 805 *
 806 * Because:
 807 *
 808 *  - the first group of each domain is its child domain; this
 809 *    gets us the first 0-1,3
 810 *  - the only uncovered node is 2, who's child domain is 1-3.
 811 *
 812 * However, because of the overlap, computing a unique CPU for each group is
 813 * more complicated. Consider for instance the groups of NODE-1 NUMA-2, both
 814 * groups include the CPUs of Node-0, while those CPUs would not in fact ever
 815 * end up at those groups (they would end up in group: 0-1,3).
 816 *
 817 * To correct this we have to introduce the group balance mask. This mask
 818 * will contain those CPUs in the group that can reach this group given the
 819 * (child) domain tree.
 820 *
 821 * With this we can once again compute balance_cpu and sched_group_capacity
 822 * relations.
 823 *
 824 * XXX include words on how balance_cpu is unique and therefore can be
 825 * used for sched_group_capacity links.
 826 *
 827 *
 828 * Another 'interesting' topology is:
 829 *
 830 *   node   0   1   2   3
 831 *     0:  10  20  20  30
 832 *     1:  20  10  20  20
 833 *     2:  20  20  10  20
 834 *     3:  30  20  20  10
 835 *
 836 * Which looks a little like:
 837 *
 838 *   0 ----- 1
 839 *   |     / |
 840 *   |   /   |
 841 *   | /     |
 842 *   2 ----- 3
 843 *
 844 * This topology is asymmetric, nodes 1,2 are fully connected, but nodes 0,3
 845 * are not.
 846 *
 847 * This leads to a few particularly weird cases where the sched_domain's are
 848 * not of the same number for each CPU. Consider:
 849 *
 850 * NUMA-2       0-3                                             0-3
 851 *  groups:     {0-2},{1-3}                                     {1-3},{0-2}
 852 *
 853 * NUMA-1       0-2             0-3             0-3             1-3
 854 *
 855 * NUMA-0       0               1               2               3
 856 *
 857 */
 858
 859
 860/*
 861 * Build the balance mask; it contains only those CPUs that can arrive at this
 862 * group and should be considered to continue balancing.
 863 *
 864 * We do this during the group creation pass, therefore the group information
 865 * isn't complete yet, however since each group represents a (child) domain we
 866 * can fully construct this using the sched_domain bits (which are already
 867 * complete).
 868 */
 869static void
 870build_balance_mask(struct sched_domain *sd, struct sched_group *sg, struct cpumask *mask)
 871{
 872        const struct cpumask *sg_span = sched_group_span(sg);
 873        struct sd_data *sdd = sd->private;
 874        struct sched_domain *sibling;
 875        int i;
 876
 877        cpumask_clear(mask);
 878
 879        for_each_cpu(i, sg_span) {
 880                sibling = *per_cpu_ptr(sdd->sd, i);
 881
 882                /*
 883                 * Can happen in the asymmetric case, where these siblings are
 884                 * unused. The mask will not be empty because those CPUs that
 885                 * do have the top domain _should_ span the domain.
 886                 */
 887                if (!sibling->child)
 888                        continue;
 889
 890                /* If we would not end up here, we can't continue from here */
 891                if (!cpumask_equal(sg_span, sched_domain_span(sibling->child)))
 892                        continue;
 893
 894                cpumask_set_cpu(i, mask);
 895        }
 896
 897        /* We must not have empty masks here */
 898        WARN_ON_ONCE(cpumask_empty(mask));
 899}
 900
 901/*
 902 * XXX: This creates per-node group entries; since the load-balancer will
 903 * immediately access remote memory to construct this group's load-balance
 904 * statistics having the groups node local is of dubious benefit.
 905 */
 906static struct sched_group *
 907build_group_from_child_sched_domain(struct sched_domain *sd, int cpu)
 908{
 909        struct sched_group *sg;
 910        struct cpumask *sg_span;
 911
 912        sg = kzalloc_node(sizeof(struct sched_group) + cpumask_size(),
 913                        GFP_KERNEL, cpu_to_node(cpu));
 914
 915        if (!sg)
 916                return NULL;
 917
 918        sg_span = sched_group_span(sg);
 919        if (sd->child)
 920                cpumask_copy(sg_span, sched_domain_span(sd->child));
 921        else
 922                cpumask_copy(sg_span, sched_domain_span(sd));
 923
 924        atomic_inc(&sg->ref);
 925        return sg;
 926}
 927
 928static void init_overlap_sched_group(struct sched_domain *sd,
 929                                     struct sched_group *sg)
 930{
 931        struct cpumask *mask = sched_domains_tmpmask2;
 932        struct sd_data *sdd = sd->private;
 933        struct cpumask *sg_span;
 934        int cpu;
 935
 936        build_balance_mask(sd, sg, mask);
 937        cpu = cpumask_first(mask);
 938
 939        sg->sgc = *per_cpu_ptr(sdd->sgc, cpu);
 940        if (atomic_inc_return(&sg->sgc->ref) == 1)
 941                cpumask_copy(group_balance_mask(sg), mask);
 942        else
 943                WARN_ON_ONCE(!cpumask_equal(group_balance_mask(sg), mask));
 944
 945        /*
 946         * Initialize sgc->capacity such that even if we mess up the
 947         * domains and no possible iteration will get us here, we won't
 948         * die on a /0 trap.
 949         */
 950        sg_span = sched_group_span(sg);
 951        sg->sgc->capacity = SCHED_CAPACITY_SCALE * cpumask_weight(sg_span);
 952        sg->sgc->min_capacity = SCHED_CAPACITY_SCALE;
 953        sg->sgc->max_capacity = SCHED_CAPACITY_SCALE;
 954}
 955
 956static struct sched_domain *
 957find_descended_sibling(struct sched_domain *sd, struct sched_domain *sibling)
 958{
 959        /*
 960         * The proper descendant would be the one whose child won't span out
 961         * of sd
 962         */
 963        while (sibling->child &&
 964               !cpumask_subset(sched_domain_span(sibling->child),
 965                               sched_domain_span(sd)))
 966                sibling = sibling->child;
 967
 968        /*
 969         * As we are referencing sgc across different topology level, we need
 970         * to go down to skip those sched_domains which don't contribute to
 971         * scheduling because they will be degenerated in cpu_attach_domain
 972         */
 973        while (sibling->child &&
 974               cpumask_equal(sched_domain_span(sibling->child),
 975                             sched_domain_span(sibling)))
 976                sibling = sibling->child;
 977
 978        return sibling;
 979}
 980
 981static int
 982build_overlap_sched_groups(struct sched_domain *sd, int cpu)
 983{
 984        struct sched_group *first = NULL, *last = NULL, *sg;
 985        const struct cpumask *span = sched_domain_span(sd);
 986        struct cpumask *covered = sched_domains_tmpmask;
 987        struct sd_data *sdd = sd->private;
 988        struct sched_domain *sibling;
 989        int i;
 990
 991        cpumask_clear(covered);
 992
 993        for_each_cpu_wrap(i, span, cpu) {
 994                struct cpumask *sg_span;
 995
 996                if (cpumask_test_cpu(i, covered))
 997                        continue;
 998
 999                sibling = *per_cpu_ptr(sdd->sd, i);
1000
1001                /*
1002                 * Asymmetric node setups can result in situations where the
1003                 * domain tree is of unequal depth, make sure to skip domains
1004                 * that already cover the entire range.
1005                 *
1006                 * In that case build_sched_domains() will have terminated the
1007                 * iteration early and our sibling sd spans will be empty.
1008                 * Domains should always include the CPU they're built on, so
1009                 * check that.
1010                 */
1011                if (!cpumask_test_cpu(i, sched_domain_span(sibling)))
1012                        continue;
1013
1014                /*
1015                 * Usually we build sched_group by sibling's child sched_domain
1016                 * But for machines whose NUMA diameter are 3 or above, we move
1017                 * to build sched_group by sibling's proper descendant's child
1018                 * domain because sibling's child sched_domain will span out of
1019                 * the sched_domain being built as below.
1020                 *
1021                 * Smallest diameter=3 topology is:
1022                 *
1023                 *   node   0   1   2   3
1024                 *     0:  10  20  30  40
1025                 *     1:  20  10  20  30
1026                 *     2:  30  20  10  20
1027                 *     3:  40  30  20  10
1028                 *
1029                 *   0 --- 1 --- 2 --- 3
1030                 *
1031                 * NUMA-3       0-3             N/A             N/A             0-3
1032                 *  groups:     {0-2},{1-3}                                     {1-3},{0-2}
1033                 *
1034                 * NUMA-2       0-2             0-3             0-3             1-3
1035                 *  groups:     {0-1},{1-3}     {0-2},{2-3}     {1-3},{0-1}     {2-3},{0-2}
1036                 *
1037                 * NUMA-1       0-1             0-2             1-3             2-3
1038                 *  groups:     {0},{1}         {1},{2},{0}     {2},{3},{1}     {3},{2}
1039                 *
1040                 * NUMA-0       0               1               2               3
1041                 *
1042                 * The NUMA-2 groups for nodes 0 and 3 are obviously buggered, as the
1043                 * group span isn't a subset of the domain span.
1044                 */
1045                if (sibling->child &&
1046                    !cpumask_subset(sched_domain_span(sibling->child), span))
1047                        sibling = find_descended_sibling(sd, sibling);
1048
1049                sg = build_group_from_child_sched_domain(sibling, cpu);
1050                if (!sg)
1051                        goto fail;
1052
1053                sg_span = sched_group_span(sg);
1054                cpumask_or(covered, covered, sg_span);
1055
1056                init_overlap_sched_group(sibling, sg);
1057
1058                if (!first)
1059                        first = sg;
1060                if (last)
1061                        last->next = sg;
1062                last = sg;
1063                last->next = first;
1064        }
1065        sd->groups = first;
1066
1067        return 0;
1068
1069fail:
1070        free_sched_groups(first, 0);
1071
1072        return -ENOMEM;
1073}
1074
1075
1076/*
1077 * Package topology (also see the load-balance blurb in fair.c)
1078 *
1079 * The scheduler builds a tree structure to represent a number of important
1080 * topology features. By default (default_topology[]) these include:
1081 *
1082 *  - Simultaneous multithreading (SMT)
1083 *  - Multi-Core Cache (MC)
1084 *  - Package (DIE)
1085 *
1086 * Where the last one more or less denotes everything up to a NUMA node.
1087 *
1088 * The tree consists of 3 primary data structures:
1089 *
1090 *      sched_domain -> sched_group -> sched_group_capacity
1091 *          ^ ^             ^ ^
1092 *          `-'             `-'
1093 *
1094 * The sched_domains are per-CPU and have a two way link (parent & child) and
1095 * denote the ever growing mask of CPUs belonging to that level of topology.
1096 *
1097 * Each sched_domain has a circular (double) linked list of sched_group's, each
1098 * denoting the domains of the level below (or individual CPUs in case of the
1099 * first domain level). The sched_group linked by a sched_domain includes the
1100 * CPU of that sched_domain [*].
1101 *
1102 * Take for instance a 2 threaded, 2 core, 2 cache cluster part:
1103 *
1104 * CPU   0   1   2   3   4   5   6   7
1105 *
1106 * DIE  [                             ]
1107 * MC   [             ] [             ]
1108 * SMT  [     ] [     ] [     ] [     ]
1109 *
1110 *  - or -
1111 *
1112 * DIE  0-7 0-7 0-7 0-7 0-7 0-7 0-7 0-7
1113 * MC   0-3 0-3 0-3 0-3 4-7 4-7 4-7 4-7
1114 * SMT  0-1 0-1 2-3 2-3 4-5 4-5 6-7 6-7
1115 *
1116 * CPU   0   1   2   3   4   5   6   7
1117 *
1118 * One way to think about it is: sched_domain moves you up and down among these
1119 * topology levels, while sched_group moves you sideways through it, at child
1120 * domain granularity.
1121 *
1122 * sched_group_capacity ensures each unique sched_group has shared storage.
1123 *
1124 * There are two related construction problems, both require a CPU that
1125 * uniquely identify each group (for a given domain):
1126 *
1127 *  - The first is the balance_cpu (see should_we_balance() and the
1128 *    load-balance blub in fair.c); for each group we only want 1 CPU to
1129 *    continue balancing at a higher domain.
1130 *
1131 *  - The second is the sched_group_capacity; we want all identical groups
1132 *    to share a single sched_group_capacity.
1133 *
1134 * Since these topologies are exclusive by construction. That is, its
1135 * impossible for an SMT thread to belong to multiple cores, and cores to
1136 * be part of multiple caches. There is a very clear and unique location
1137 * for each CPU in the hierarchy.
1138 *
1139 * Therefore computing a unique CPU for each group is trivial (the iteration
1140 * mask is redundant and set all 1s; all CPUs in a group will end up at _that_
1141 * group), we can simply pick the first CPU in each group.
1142 *
1143 *
1144 * [*] in other words, the first group of each domain is its child domain.
1145 */
1146
1147static struct sched_group *get_group(int cpu, struct sd_data *sdd)
1148{
1149        struct sched_domain *sd = *per_cpu_ptr(sdd->sd, cpu);
1150        struct sched_domain *child = sd->child;
1151        struct sched_group *sg;
1152        bool already_visited;
1153
1154        if (child)
1155                cpu = cpumask_first(sched_domain_span(child));
1156
1157        sg = *per_cpu_ptr(sdd->sg, cpu);
1158        sg->sgc = *per_cpu_ptr(sdd->sgc, cpu);
1159
1160        /* Increase refcounts for claim_allocations: */
1161        already_visited = atomic_inc_return(&sg->ref) > 1;
1162        /* sgc visits should follow a similar trend as sg */
1163        WARN_ON(already_visited != (atomic_inc_return(&sg->sgc->ref) > 1));
1164
1165        /* If we have already visited that group, it's already initialized. */
1166        if (already_visited)
1167                return sg;
1168
1169        if (child) {
1170                cpumask_copy(sched_group_span(sg), sched_domain_span(child));
1171                cpumask_copy(group_balance_mask(sg), sched_group_span(sg));
1172        } else {
1173                cpumask_set_cpu(cpu, sched_group_span(sg));
1174                cpumask_set_cpu(cpu, group_balance_mask(sg));
1175        }
1176
1177        sg->sgc->capacity = SCHED_CAPACITY_SCALE * cpumask_weight(sched_group_span(sg));
1178        sg->sgc->min_capacity = SCHED_CAPACITY_SCALE;
1179        sg->sgc->max_capacity = SCHED_CAPACITY_SCALE;
1180
1181        return sg;
1182}
1183
1184/*
1185 * build_sched_groups will build a circular linked list of the groups
1186 * covered by the given span, will set each group's ->cpumask correctly,
1187 * and will initialize their ->sgc.
1188 *
1189 * Assumes the sched_domain tree is fully constructed
1190 */
1191static int
1192build_sched_groups(struct sched_domain *sd, int cpu)
1193{
1194        struct sched_group *first = NULL, *last = NULL;
1195        struct sd_data *sdd = sd->private;
1196        const struct cpumask *span = sched_domain_span(sd);
1197        struct cpumask *covered;
1198        int i;
1199
1200        lockdep_assert_held(&sched_domains_mutex);
1201        covered = sched_domains_tmpmask;
1202
1203        cpumask_clear(covered);
1204
1205        for_each_cpu_wrap(i, span, cpu) {
1206                struct sched_group *sg;
1207
1208                if (cpumask_test_cpu(i, covered))
1209                        continue;
1210
1211                sg = get_group(i, sdd);
1212
1213                cpumask_or(covered, covered, sched_group_span(sg));
1214
1215                if (!first)
1216                        first = sg;
1217                if (last)
1218                        last->next = sg;
1219                last = sg;
1220        }
1221        last->next = first;
1222        sd->groups = first;
1223
1224        return 0;
1225}
1226
1227/*
1228 * Initialize sched groups cpu_capacity.
1229 *
1230 * cpu_capacity indicates the capacity of sched group, which is used while
1231 * distributing the load between different sched groups in a sched domain.
1232 * Typically cpu_capacity for all the groups in a sched domain will be same
1233 * unless there are asymmetries in the topology. If there are asymmetries,
1234 * group having more cpu_capacity will pickup more load compared to the
1235 * group having less cpu_capacity.
1236 */
1237static void init_sched_groups_capacity(int cpu, struct sched_domain *sd)
1238{
1239        struct sched_group *sg = sd->groups;
1240
1241        WARN_ON(!sg);
1242
1243        do {
1244                int cpu, max_cpu = -1;
1245
1246                sg->group_weight = cpumask_weight(sched_group_span(sg));
1247
1248                if (!(sd->flags & SD_ASYM_PACKING))
1249                        goto next;
1250
1251                for_each_cpu(cpu, sched_group_span(sg)) {
1252                        if (max_cpu < 0)
1253                                max_cpu = cpu;
1254                        else if (sched_asym_prefer(cpu, max_cpu))
1255                                max_cpu = cpu;
1256                }
1257                sg->asym_prefer_cpu = max_cpu;
1258
1259next:
1260                sg = sg->next;
1261        } while (sg != sd->groups);
1262
1263        if (cpu != group_balance_cpu(sg))
1264                return;
1265
1266        update_group_capacity(sd, cpu);
1267}
1268
1269/*
1270 * Asymmetric CPU capacity bits
1271 */
1272struct asym_cap_data {
1273        struct list_head link;
1274        unsigned long capacity;
1275        unsigned long cpus[];
1276};
1277
1278/*
1279 * Set of available CPUs grouped by their corresponding capacities
1280 * Each list entry contains a CPU mask reflecting CPUs that share the same
1281 * capacity.
1282 * The lifespan of data is unlimited.
1283 */
1284static LIST_HEAD(asym_cap_list);
1285
1286#define cpu_capacity_span(asym_data) to_cpumask((asym_data)->cpus)
1287
1288/*
1289 * Verify whether there is any CPU capacity asymmetry in a given sched domain.
1290 * Provides sd_flags reflecting the asymmetry scope.
1291 */
1292static inline int
1293asym_cpu_capacity_classify(const struct cpumask *sd_span,
1294                           const struct cpumask *cpu_map)
1295{
1296        struct asym_cap_data *entry;
1297        int count = 0, miss = 0;
1298
1299        /*
1300         * Count how many unique CPU capacities this domain spans across
1301         * (compare sched_domain CPUs mask with ones representing  available
1302         * CPUs capacities). Take into account CPUs that might be offline:
1303         * skip those.
1304         */
1305        list_for_each_entry(entry, &asym_cap_list, link) {
1306                if (cpumask_intersects(sd_span, cpu_capacity_span(entry)))
1307                        ++count;
1308                else if (cpumask_intersects(cpu_map, cpu_capacity_span(entry)))
1309                        ++miss;
1310        }
1311
1312        WARN_ON_ONCE(!count && !list_empty(&asym_cap_list));
1313
1314        /* No asymmetry detected */
1315        if (count < 2)
1316                return 0;
1317        /* Some of the available CPU capacity values have not been detected */
1318        if (miss)
1319                return SD_ASYM_CPUCAPACITY;
1320
1321        /* Full asymmetry */
1322        return SD_ASYM_CPUCAPACITY | SD_ASYM_CPUCAPACITY_FULL;
1323
1324}
1325
1326static inline void asym_cpu_capacity_update_data(int cpu)
1327{
1328        unsigned long capacity = arch_scale_cpu_capacity(cpu);
1329        struct asym_cap_data *entry = NULL;
1330
1331        list_for_each_entry(entry, &asym_cap_list, link) {
1332                if (capacity == entry->capacity)
1333                        goto done;
1334        }
1335
1336        entry = kzalloc(sizeof(*entry) + cpumask_size(), GFP_KERNEL);
1337        if (WARN_ONCE(!entry, "Failed to allocate memory for asymmetry data\n"))
1338                return;
1339        entry->capacity = capacity;
1340        list_add(&entry->link, &asym_cap_list);
1341done:
1342        __cpumask_set_cpu(cpu, cpu_capacity_span(entry));
1343}
1344
1345/*
1346 * Build-up/update list of CPUs grouped by their capacities
1347 * An update requires explicit request to rebuild sched domains
1348 * with state indicating CPU topology changes.
1349 */
1350static void asym_cpu_capacity_scan(void)
1351{
1352        struct asym_cap_data *entry, *next;
1353        int cpu;
1354
1355        list_for_each_entry(entry, &asym_cap_list, link)
1356                cpumask_clear(cpu_capacity_span(entry));
1357
1358        for_each_cpu_and(cpu, cpu_possible_mask, housekeeping_cpumask(HK_FLAG_DOMAIN))
1359                asym_cpu_capacity_update_data(cpu);
1360
1361        list_for_each_entry_safe(entry, next, &asym_cap_list, link) {
1362                if (cpumask_empty(cpu_capacity_span(entry))) {
1363                        list_del(&entry->link);
1364                        kfree(entry);
1365                }
1366        }
1367
1368        /*
1369         * Only one capacity value has been detected i.e. this system is symmetric.
1370         * No need to keep this data around.
1371         */
1372        if (list_is_singular(&asym_cap_list)) {
1373                entry = list_first_entry(&asym_cap_list, typeof(*entry), link);
1374                list_del(&entry->link);
1375                kfree(entry);
1376        }
1377}
1378
1379/*
1380 * Initializers for schedule domains
1381 * Non-inlined to reduce accumulated stack pressure in build_sched_domains()
1382 */
1383
1384static int default_relax_domain_level = -1;
1385int sched_domain_level_max;
1386
1387static int __init setup_relax_domain_level(char *str)
1388{
1389        if (kstrtoint(str, 0, &default_relax_domain_level))
1390                pr_warn("Unable to set relax_domain_level\n");
1391
1392        return 1;
1393}
1394__setup("relax_domain_level=", setup_relax_domain_level);
1395
1396static void set_domain_attribute(struct sched_domain *sd,
1397                                 struct sched_domain_attr *attr)
1398{
1399        int request;
1400
1401        if (!attr || attr->relax_domain_level < 0) {
1402                if (default_relax_domain_level < 0)
1403                        return;
1404                request = default_relax_domain_level;
1405        } else
1406                request = attr->relax_domain_level;
1407
1408        if (sd->level > request) {
1409                /* Turn off idle balance on this domain: */
1410                sd->flags &= ~(SD_BALANCE_WAKE|SD_BALANCE_NEWIDLE);
1411        }
1412}
1413
1414static void __sdt_free(const struct cpumask *cpu_map);
1415static int __sdt_alloc(const struct cpumask *cpu_map);
1416
1417static void __free_domain_allocs(struct s_data *d, enum s_alloc what,
1418                                 const struct cpumask *cpu_map)
1419{
1420        switch (what) {
1421        case sa_rootdomain:
1422                if (!atomic_read(&d->rd->refcount))
1423                        free_rootdomain(&d->rd->rcu);
1424                fallthrough;
1425        case sa_sd:
1426                free_percpu(d->sd);
1427                fallthrough;
1428        case sa_sd_storage:
1429                __sdt_free(cpu_map);
1430                fallthrough;
1431        case sa_none:
1432                break;
1433        }
1434}
1435
1436static enum s_alloc
1437__visit_domain_allocation_hell(struct s_data *d, const struct cpumask *cpu_map)
1438{
1439        memset(d, 0, sizeof(*d));
1440
1441        if (__sdt_alloc(cpu_map))
1442                return sa_sd_storage;
1443        d->sd = alloc_percpu(struct sched_domain *);
1444        if (!d->sd)
1445                return sa_sd_storage;
1446        d->rd = alloc_rootdomain();
1447        if (!d->rd)
1448                return sa_sd;
1449
1450        return sa_rootdomain;
1451}
1452
1453/*
1454 * NULL the sd_data elements we've used to build the sched_domain and
1455 * sched_group structure so that the subsequent __free_domain_allocs()
1456 * will not free the data we're using.
1457 */
1458static void claim_allocations(int cpu, struct sched_domain *sd)
1459{
1460        struct sd_data *sdd = sd->private;
1461
1462        WARN_ON_ONCE(*per_cpu_ptr(sdd->sd, cpu) != sd);
1463        *per_cpu_ptr(sdd->sd, cpu) = NULL;
1464
1465        if (atomic_read(&(*per_cpu_ptr(sdd->sds, cpu))->ref))
1466                *per_cpu_ptr(sdd->sds, cpu) = NULL;
1467
1468        if (atomic_read(&(*per_cpu_ptr(sdd->sg, cpu))->ref))
1469                *per_cpu_ptr(sdd->sg, cpu) = NULL;
1470
1471        if (atomic_read(&(*per_cpu_ptr(sdd->sgc, cpu))->ref))
1472                *per_cpu_ptr(sdd->sgc, cpu) = NULL;
1473}
1474
1475#ifdef CONFIG_NUMA
1476enum numa_topology_type sched_numa_topology_type;
1477
1478static int                      sched_domains_numa_levels;
1479static int                      sched_domains_curr_level;
1480
1481int                             sched_max_numa_distance;
1482static int                      *sched_domains_numa_distance;
1483static struct cpumask           ***sched_domains_numa_masks;
1484int __read_mostly               node_reclaim_distance = RECLAIM_DISTANCE;
1485#endif
1486
1487/*
1488 * SD_flags allowed in topology descriptions.
1489 *
1490 * These flags are purely descriptive of the topology and do not prescribe
1491 * behaviour. Behaviour is artificial and mapped in the below sd_init()
1492 * function:
1493 *
1494 *   SD_SHARE_CPUCAPACITY   - describes SMT topologies
1495 *   SD_SHARE_PKG_RESOURCES - describes shared caches
1496 *   SD_NUMA                - describes NUMA topologies
1497 *
1498 * Odd one out, which beside describing the topology has a quirk also
1499 * prescribes the desired behaviour that goes along with it:
1500 *
1501 *   SD_ASYM_PACKING        - describes SMT quirks
1502 */
1503#define TOPOLOGY_SD_FLAGS               \
1504        (SD_SHARE_CPUCAPACITY   |       \
1505         SD_SHARE_PKG_RESOURCES |       \
1506         SD_NUMA                |       \
1507         SD_ASYM_PACKING)
1508
1509static struct sched_domain *
1510sd_init(struct sched_domain_topology_level *tl,
1511        const struct cpumask *cpu_map,
1512        struct sched_domain *child, int cpu)
1513{
1514        struct sd_data *sdd = &tl->data;
1515        struct sched_domain *sd = *per_cpu_ptr(sdd->sd, cpu);
1516        int sd_id, sd_weight, sd_flags = 0;
1517        struct cpumask *sd_span;
1518
1519#ifdef CONFIG_NUMA
1520        /*
1521         * Ugly hack to pass state to sd_numa_mask()...
1522         */
1523        sched_domains_curr_level = tl->numa_level;
1524#endif
1525
1526        sd_weight = cpumask_weight(tl->mask(cpu));
1527
1528        if (tl->sd_flags)
1529                sd_flags = (*tl->sd_flags)();
1530        if (WARN_ONCE(sd_flags & ~TOPOLOGY_SD_FLAGS,
1531                        "wrong sd_flags in topology description\n"))
1532                sd_flags &= TOPOLOGY_SD_FLAGS;
1533
1534        *sd = (struct sched_domain){
1535                .min_interval           = sd_weight,
1536                .max_interval           = 2*sd_weight,
1537                .busy_factor            = 16,
1538                .imbalance_pct          = 117,
1539
1540                .cache_nice_tries       = 0,
1541
1542                .flags                  = 1*SD_BALANCE_NEWIDLE
1543                                        | 1*SD_BALANCE_EXEC
1544                                        | 1*SD_BALANCE_FORK
1545                                        | 0*SD_BALANCE_WAKE
1546                                        | 1*SD_WAKE_AFFINE
1547                                        | 0*SD_SHARE_CPUCAPACITY
1548                                        | 0*SD_SHARE_PKG_RESOURCES
1549                                        | 0*SD_SERIALIZE
1550                                        | 1*SD_PREFER_SIBLING
1551                                        | 0*SD_NUMA
1552                                        | sd_flags
1553                                        ,
1554
1555                .last_balance           = jiffies,
1556                .balance_interval       = sd_weight,
1557                .max_newidle_lb_cost    = 0,
1558                .next_decay_max_lb_cost = jiffies,
1559                .child                  = child,
1560#ifdef CONFIG_SCHED_DEBUG
1561                .name                   = tl->name,
1562#endif
1563        };
1564
1565        sd_span = sched_domain_span(sd);
1566        cpumask_and(sd_span, cpu_map, tl->mask(cpu));
1567        sd_id = cpumask_first(sd_span);
1568
1569        sd->flags |= asym_cpu_capacity_classify(sd_span, cpu_map);
1570
1571        WARN_ONCE((sd->flags & (SD_SHARE_CPUCAPACITY | SD_ASYM_CPUCAPACITY)) ==
1572                  (SD_SHARE_CPUCAPACITY | SD_ASYM_CPUCAPACITY),
1573                  "CPU capacity asymmetry not supported on SMT\n");
1574
1575        /*
1576         * Convert topological properties into behaviour.
1577         */
1578        /* Don't attempt to spread across CPUs of different capacities. */
1579        if ((sd->flags & SD_ASYM_CPUCAPACITY) && sd->child)
1580                sd->child->flags &= ~SD_PREFER_SIBLING;
1581
1582        if (sd->flags & SD_SHARE_CPUCAPACITY) {
1583                sd->imbalance_pct = 110;
1584
1585        } else if (sd->flags & SD_SHARE_PKG_RESOURCES) {
1586                sd->imbalance_pct = 117;
1587                sd->cache_nice_tries = 1;
1588
1589#ifdef CONFIG_NUMA
1590        } else if (sd->flags & SD_NUMA) {
1591                sd->cache_nice_tries = 2;
1592
1593                sd->flags &= ~SD_PREFER_SIBLING;
1594                sd->flags |= SD_SERIALIZE;
1595                if (sched_domains_numa_distance[tl->numa_level] > node_reclaim_distance) {
1596                        sd->flags &= ~(SD_BALANCE_EXEC |
1597                                       SD_BALANCE_FORK |
1598                                       SD_WAKE_AFFINE);
1599                }
1600
1601#endif
1602        } else {
1603                sd->cache_nice_tries = 1;
1604        }
1605
1606        /*
1607         * For all levels sharing cache; connect a sched_domain_shared
1608         * instance.
1609         */
1610        if (sd->flags & SD_SHARE_PKG_RESOURCES) {
1611                sd->shared = *per_cpu_ptr(sdd->sds, sd_id);
1612                atomic_inc(&sd->shared->ref);
1613                atomic_set(&sd->shared->nr_busy_cpus, sd_weight);
1614        }
1615
1616        sd->private = sdd;
1617
1618        return sd;
1619}
1620
1621/*
1622 * Topology list, bottom-up.
1623 */
1624static struct sched_domain_topology_level default_topology[] = {
1625#ifdef CONFIG_SCHED_SMT
1626        { cpu_smt_mask, cpu_smt_flags, SD_INIT_NAME(SMT) },
1627#endif
1628#ifdef CONFIG_SCHED_MC
1629        { cpu_coregroup_mask, cpu_core_flags, SD_INIT_NAME(MC) },
1630#endif
1631        { cpu_cpu_mask, SD_INIT_NAME(DIE) },
1632        { NULL, },
1633};
1634
1635static struct sched_domain_topology_level *sched_domain_topology =
1636        default_topology;
1637
1638#define for_each_sd_topology(tl)                        \
1639        for (tl = sched_domain_topology; tl->mask; tl++)
1640
1641void set_sched_topology(struct sched_domain_topology_level *tl)
1642{
1643        if (WARN_ON_ONCE(sched_smp_initialized))
1644                return;
1645
1646        sched_domain_topology = tl;
1647}
1648
1649#ifdef CONFIG_NUMA
1650
1651static const struct cpumask *sd_numa_mask(int cpu)
1652{
1653        return sched_domains_numa_masks[sched_domains_curr_level][cpu_to_node(cpu)];
1654}
1655
1656static void sched_numa_warn(const char *str)
1657{
1658        static int done = false;
1659        int i,j;
1660
1661        if (done)
1662                return;
1663
1664        done = true;
1665
1666        printk(KERN_WARNING "ERROR: %s\n\n", str);
1667
1668        for (i = 0; i < nr_node_ids; i++) {
1669                printk(KERN_WARNING "  ");
1670                for (j = 0; j < nr_node_ids; j++)
1671                        printk(KERN_CONT "%02d ", node_distance(i,j));
1672                printk(KERN_CONT "\n");
1673        }
1674        printk(KERN_WARNING "\n");
1675}
1676
1677bool find_numa_distance(int distance)
1678{
1679        int i;
1680
1681        if (distance == node_distance(0, 0))
1682                return true;
1683
1684        for (i = 0; i < sched_domains_numa_levels; i++) {
1685                if (sched_domains_numa_distance[i] == distance)
1686                        return true;
1687        }
1688
1689        return false;
1690}
1691
1692/*
1693 * A system can have three types of NUMA topology:
1694 * NUMA_DIRECT: all nodes are directly connected, or not a NUMA system
1695 * NUMA_GLUELESS_MESH: some nodes reachable through intermediary nodes
1696 * NUMA_BACKPLANE: nodes can reach other nodes through a backplane
1697 *
1698 * The difference between a glueless mesh topology and a backplane
1699 * topology lies in whether communication between not directly
1700 * connected nodes goes through intermediary nodes (where programs
1701 * could run), or through backplane controllers. This affects
1702 * placement of programs.
1703 *
1704 * The type of topology can be discerned with the following tests:
1705 * - If the maximum distance between any nodes is 1 hop, the system
1706 *   is directly connected.
1707 * - If for two nodes A and B, located N > 1 hops away from each other,
1708 *   there is an intermediary node C, which is < N hops away from both
1709 *   nodes A and B, the system is a glueless mesh.
1710 */
1711static void init_numa_topology_type(void)
1712{
1713        int a, b, c, n;
1714
1715        n = sched_max_numa_distance;
1716
1717        if (sched_domains_numa_levels <= 2) {
1718                sched_numa_topology_type = NUMA_DIRECT;
1719                return;
1720        }
1721
1722        for_each_online_node(a) {
1723                for_each_online_node(b) {
1724                        /* Find two nodes furthest removed from each other. */
1725                        if (node_distance(a, b) < n)
1726                                continue;
1727
1728                        /* Is there an intermediary node between a and b? */
1729                        for_each_online_node(c) {
1730                                if (node_distance(a, c) < n &&
1731                                    node_distance(b, c) < n) {
1732                                        sched_numa_topology_type =
1733                                                        NUMA_GLUELESS_MESH;
1734                                        return;
1735                                }
1736                        }
1737
1738                        sched_numa_topology_type = NUMA_BACKPLANE;
1739                        return;
1740                }
1741        }
1742}
1743
1744
1745#define NR_DISTANCE_VALUES (1 << DISTANCE_BITS)
1746
1747void sched_init_numa(void)
1748{
1749        struct sched_domain_topology_level *tl;
1750        unsigned long *distance_map;
1751        int nr_levels = 0;
1752        int i, j;
1753
1754        /*
1755         * O(nr_nodes^2) deduplicating selection sort -- in order to find the
1756         * unique distances in the node_distance() table.
1757         */
1758        distance_map = bitmap_alloc(NR_DISTANCE_VALUES, GFP_KERNEL);
1759        if (!distance_map)
1760                return;
1761
1762        bitmap_zero(distance_map, NR_DISTANCE_VALUES);
1763        for (i = 0; i < nr_node_ids; i++) {
1764                for (j = 0; j < nr_node_ids; j++) {
1765                        int distance = node_distance(i, j);
1766
1767                        if (distance < LOCAL_DISTANCE || distance >= NR_DISTANCE_VALUES) {
1768                                sched_numa_warn("Invalid distance value range");
1769                                return;
1770                        }
1771
1772                        bitmap_set(distance_map, distance, 1);
1773                }
1774        }
1775        /*
1776         * We can now figure out how many unique distance values there are and
1777         * allocate memory accordingly.
1778         */
1779        nr_levels = bitmap_weight(distance_map, NR_DISTANCE_VALUES);
1780
1781        sched_domains_numa_distance = kcalloc(nr_levels, sizeof(int), GFP_KERNEL);
1782        if (!sched_domains_numa_distance) {
1783                bitmap_free(distance_map);
1784                return;
1785        }
1786
1787        for (i = 0, j = 0; i < nr_levels; i++, j++) {
1788                j = find_next_bit(distance_map, NR_DISTANCE_VALUES, j);
1789                sched_domains_numa_distance[i] = j;
1790        }
1791
1792        bitmap_free(distance_map);
1793
1794        /*
1795         * 'nr_levels' contains the number of unique distances
1796         *
1797         * The sched_domains_numa_distance[] array includes the actual distance
1798         * numbers.
1799         */
1800
1801        /*
1802         * Here, we should temporarily reset sched_domains_numa_levels to 0.
1803         * If it fails to allocate memory for array sched_domains_numa_masks[][],
1804         * the array will contain less then 'nr_levels' members. This could be
1805         * dangerous when we use it to iterate array sched_domains_numa_masks[][]
1806         * in other functions.
1807         *
1808         * We reset it to 'nr_levels' at the end of this function.
1809         */
1810        sched_domains_numa_levels = 0;
1811
1812        sched_domains_numa_masks = kzalloc(sizeof(void *) * nr_levels, GFP_KERNEL);
1813        if (!sched_domains_numa_masks)
1814                return;
1815
1816        /*
1817         * Now for each level, construct a mask per node which contains all
1818         * CPUs of nodes that are that many hops away from us.
1819         */
1820        for (i = 0; i < nr_levels; i++) {
1821                sched_domains_numa_masks[i] =
1822                        kzalloc(nr_node_ids * sizeof(void *), GFP_KERNEL);
1823                if (!sched_domains_numa_masks[i])
1824                        return;
1825
1826                for (j = 0; j < nr_node_ids; j++) {
1827                        struct cpumask *mask = kzalloc(cpumask_size(), GFP_KERNEL);
1828                        int k;
1829
1830                        if (!mask)
1831                                return;
1832
1833                        sched_domains_numa_masks[i][j] = mask;
1834
1835                        for_each_node(k) {
1836                                if (sched_debug() && (node_distance(j, k) != node_distance(k, j)))
1837                                        sched_numa_warn("Node-distance not symmetric");
1838
1839                                if (node_distance(j, k) > sched_domains_numa_distance[i])
1840                                        continue;
1841
1842                                cpumask_or(mask, mask, cpumask_of_node(k));
1843                        }
1844                }
1845        }
1846
1847        /* Compute default topology size */
1848        for (i = 0; sched_domain_topology[i].mask; i++);
1849
1850        tl = kzalloc((i + nr_levels + 1) *
1851                        sizeof(struct sched_domain_topology_level), GFP_KERNEL);
1852        if (!tl)
1853                return;
1854
1855        /*
1856         * Copy the default topology bits..
1857         */
1858        for (i = 0; sched_domain_topology[i].mask; i++)
1859                tl[i] = sched_domain_topology[i];
1860
1861        /*
1862         * Add the NUMA identity distance, aka single NODE.
1863         */
1864        tl[i++] = (struct sched_domain_topology_level){
1865                .mask = sd_numa_mask,
1866                .numa_level = 0,
1867                SD_INIT_NAME(NODE)
1868        };
1869
1870        /*
1871         * .. and append 'j' levels of NUMA goodness.
1872         */
1873        for (j = 1; j < nr_levels; i++, j++) {
1874                tl[i] = (struct sched_domain_topology_level){
1875                        .mask = sd_numa_mask,
1876                        .sd_flags = cpu_numa_flags,
1877                        .flags = SDTL_OVERLAP,
1878                        .numa_level = j,
1879                        SD_INIT_NAME(NUMA)
1880                };
1881        }
1882
1883        sched_domain_topology = tl;
1884
1885        sched_domains_numa_levels = nr_levels;
1886        sched_max_numa_distance = sched_domains_numa_distance[nr_levels - 1];
1887
1888        init_numa_topology_type();
1889}
1890
1891void sched_domains_numa_masks_set(unsigned int cpu)
1892{
1893        int node = cpu_to_node(cpu);
1894        int i, j;
1895
1896        for (i = 0; i < sched_domains_numa_levels; i++) {
1897                for (j = 0; j < nr_node_ids; j++) {
1898                        if (node_distance(j, node) <= sched_domains_numa_distance[i])
1899                                cpumask_set_cpu(cpu, sched_domains_numa_masks[i][j]);
1900                }
1901        }
1902}
1903
1904void sched_domains_numa_masks_clear(unsigned int cpu)
1905{
1906        int i, j;
1907
1908        for (i = 0; i < sched_domains_numa_levels; i++) {
1909                for (j = 0; j < nr_node_ids; j++)
1910                        cpumask_clear_cpu(cpu, sched_domains_numa_masks[i][j]);
1911        }
1912}
1913
1914/*
1915 * sched_numa_find_closest() - given the NUMA topology, find the cpu
1916 *                             closest to @cpu from @cpumask.
1917 * cpumask: cpumask to find a cpu from
1918 * cpu: cpu to be close to
1919 *
1920 * returns: cpu, or nr_cpu_ids when nothing found.
1921 */
1922int sched_numa_find_closest(const struct cpumask *cpus, int cpu)
1923{
1924        int i, j = cpu_to_node(cpu);
1925
1926        for (i = 0; i < sched_domains_numa_levels; i++) {
1927                cpu = cpumask_any_and(cpus, sched_domains_numa_masks[i][j]);
1928                if (cpu < nr_cpu_ids)
1929                        return cpu;
1930        }
1931        return nr_cpu_ids;
1932}
1933
1934#endif /* CONFIG_NUMA */
1935
1936static int __sdt_alloc(const struct cpumask *cpu_map)
1937{
1938        struct sched_domain_topology_level *tl;
1939        int j;
1940
1941        for_each_sd_topology(tl) {
1942                struct sd_data *sdd = &tl->data;
1943
1944                sdd->sd = alloc_percpu(struct sched_domain *);
1945                if (!sdd->sd)
1946                        return -ENOMEM;
1947
1948                sdd->sds = alloc_percpu(struct sched_domain_shared *);
1949                if (!sdd->sds)
1950                        return -ENOMEM;
1951
1952                sdd->sg = alloc_percpu(struct sched_group *);
1953                if (!sdd->sg)
1954                        return -ENOMEM;
1955
1956                sdd->sgc = alloc_percpu(struct sched_group_capacity *);
1957                if (!sdd->sgc)
1958                        return -ENOMEM;
1959
1960                for_each_cpu(j, cpu_map) {
1961                        struct sched_domain *sd;
1962                        struct sched_domain_shared *sds;
1963                        struct sched_group *sg;
1964                        struct sched_group_capacity *sgc;
1965
1966                        sd = kzalloc_node(sizeof(struct sched_domain) + cpumask_size(),
1967                                        GFP_KERNEL, cpu_to_node(j));
1968                        if (!sd)
1969                                return -ENOMEM;
1970
1971                        *per_cpu_ptr(sdd->sd, j) = sd;
1972
1973                        sds = kzalloc_node(sizeof(struct sched_domain_shared),
1974                                        GFP_KERNEL, cpu_to_node(j));
1975                        if (!sds)
1976                                return -ENOMEM;
1977
1978                        *per_cpu_ptr(sdd->sds, j) = sds;
1979
1980                        sg = kzalloc_node(sizeof(struct sched_group) + cpumask_size(),
1981                                        GFP_KERNEL, cpu_to_node(j));
1982                        if (!sg)
1983                                return -ENOMEM;
1984
1985                        sg->next = sg;
1986
1987                        *per_cpu_ptr(sdd->sg, j) = sg;
1988
1989                        sgc = kzalloc_node(sizeof(struct sched_group_capacity) + cpumask_size(),
1990                                        GFP_KERNEL, cpu_to_node(j));
1991                        if (!sgc)
1992                                return -ENOMEM;
1993
1994#ifdef CONFIG_SCHED_DEBUG
1995                        sgc->id = j;
1996#endif
1997
1998                        *per_cpu_ptr(sdd->sgc, j) = sgc;
1999                }
2000        }
2001
2002        return 0;
2003}
2004
2005static void __sdt_free(const struct cpumask *cpu_map)
2006{
2007        struct sched_domain_topology_level *tl;
2008        int j;
2009
2010        for_each_sd_topology(tl) {
2011                struct sd_data *sdd = &tl->data;
2012
2013                for_each_cpu(j, cpu_map) {
2014                        struct sched_domain *sd;
2015
2016                        if (sdd->sd) {
2017                                sd = *per_cpu_ptr(sdd->sd, j);
2018                                if (sd && (sd->flags & SD_OVERLAP))
2019                                        free_sched_groups(sd->groups, 0);
2020                                kfree(*per_cpu_ptr(sdd->sd, j));
2021                        }
2022
2023                        if (sdd->sds)
2024                                kfree(*per_cpu_ptr(sdd->sds, j));
2025                        if (sdd->sg)
2026                                kfree(*per_cpu_ptr(sdd->sg, j));
2027                        if (sdd->sgc)
2028                                kfree(*per_cpu_ptr(sdd->sgc, j));
2029                }
2030                free_percpu(sdd->sd);
2031                sdd->sd = NULL;
2032                free_percpu(sdd->sds);
2033                sdd->sds = NULL;
2034                free_percpu(sdd->sg);
2035                sdd->sg = NULL;
2036                free_percpu(sdd->sgc);
2037                sdd->sgc = NULL;
2038        }
2039}
2040
2041static struct sched_domain *build_sched_domain(struct sched_domain_topology_level *tl,
2042                const struct cpumask *cpu_map, struct sched_domain_attr *attr,
2043                struct sched_domain *child, int cpu)
2044{
2045        struct sched_domain *sd = sd_init(tl, cpu_map, child, cpu);
2046
2047        if (child) {
2048                sd->level = child->level + 1;
2049                sched_domain_level_max = max(sched_domain_level_max, sd->level);
2050                child->parent = sd;
2051
2052                if (!cpumask_subset(sched_domain_span(child),
2053                                    sched_domain_span(sd))) {
2054                        pr_err("BUG: arch topology borken\n");
2055#ifdef CONFIG_SCHED_DEBUG
2056                        pr_err("     the %s domain not a subset of the %s domain\n",
2057                                        child->name, sd->name);
2058#endif
2059                        /* Fixup, ensure @sd has at least @child CPUs. */
2060                        cpumask_or(sched_domain_span(sd),
2061                                   sched_domain_span(sd),
2062                                   sched_domain_span(child));
2063                }
2064
2065        }
2066        set_domain_attribute(sd, attr);
2067
2068        return sd;
2069}
2070
2071/*
2072 * Ensure topology masks are sane, i.e. there are no conflicts (overlaps) for
2073 * any two given CPUs at this (non-NUMA) topology level.
2074 */
2075static bool topology_span_sane(struct sched_domain_topology_level *tl,
2076                              const struct cpumask *cpu_map, int cpu)
2077{
2078        int i;
2079
2080        /* NUMA levels are allowed to overlap */
2081        if (tl->flags & SDTL_OVERLAP)
2082                return true;
2083
2084        /*
2085         * Non-NUMA levels cannot partially overlap - they must be either
2086         * completely equal or completely disjoint. Otherwise we can end up
2087         * breaking the sched_group lists - i.e. a later get_group() pass
2088         * breaks the linking done for an earlier span.
2089         */
2090        for_each_cpu(i, cpu_map) {
2091                if (i == cpu)
2092                        continue;
2093                /*
2094                 * We should 'and' all those masks with 'cpu_map' to exactly
2095                 * match the topology we're about to build, but that can only
2096                 * remove CPUs, which only lessens our ability to detect
2097                 * overlaps
2098                 */
2099                if (!cpumask_equal(tl->mask(cpu), tl->mask(i)) &&
2100                    cpumask_intersects(tl->mask(cpu), tl->mask(i)))
2101                        return false;
2102        }
2103
2104        return true;
2105}
2106
2107/*
2108 * Build sched domains for a given set of CPUs and attach the sched domains
2109 * to the individual CPUs
2110 */
2111static int
2112build_sched_domains(const struct cpumask *cpu_map, struct sched_domain_attr *attr)
2113{
2114        enum s_alloc alloc_state = sa_none;
2115        struct sched_domain *sd;
2116        struct s_data d;
2117        struct rq *rq = NULL;
2118        int i, ret = -ENOMEM;
2119        bool has_asym = false;
2120
2121        if (WARN_ON(cpumask_empty(cpu_map)))
2122                goto error;
2123
2124        alloc_state = __visit_domain_allocation_hell(&d, cpu_map);
2125        if (alloc_state != sa_rootdomain)
2126                goto error;
2127
2128        /* Set up domains for CPUs specified by the cpu_map: */
2129        for_each_cpu(i, cpu_map) {
2130                struct sched_domain_topology_level *tl;
2131
2132                sd = NULL;
2133                for_each_sd_topology(tl) {
2134
2135                        if (WARN_ON(!topology_span_sane(tl, cpu_map, i)))
2136                                goto error;
2137
2138                        sd = build_sched_domain(tl, cpu_map, attr, sd, i);
2139
2140                        has_asym |= sd->flags & SD_ASYM_CPUCAPACITY;
2141
2142                        if (tl == sched_domain_topology)
2143                                *per_cpu_ptr(d.sd, i) = sd;
2144                        if (tl->flags & SDTL_OVERLAP)
2145                                sd->flags |= SD_OVERLAP;
2146                        if (cpumask_equal(cpu_map, sched_domain_span(sd)))
2147                                break;
2148                }
2149        }
2150
2151        /* Build the groups for the domains */
2152        for_each_cpu(i, cpu_map) {
2153                for (sd = *per_cpu_ptr(d.sd, i); sd; sd = sd->parent) {
2154                        sd->span_weight = cpumask_weight(sched_domain_span(sd));
2155                        if (sd->flags & SD_OVERLAP) {
2156                                if (build_overlap_sched_groups(sd, i))
2157                                        goto error;
2158                        } else {
2159                                if (build_sched_groups(sd, i))
2160                                        goto error;
2161                        }
2162                }
2163        }
2164
2165        /* Calculate CPU capacity for physical packages and nodes */
2166        for (i = nr_cpumask_bits-1; i >= 0; i--) {
2167                if (!cpumask_test_cpu(i, cpu_map))
2168                        continue;
2169
2170                for (sd = *per_cpu_ptr(d.sd, i); sd; sd = sd->parent) {
2171                        claim_allocations(i, sd);
2172                        init_sched_groups_capacity(i, sd);
2173                }
2174        }
2175
2176        /* Attach the domains */
2177        rcu_read_lock();
2178        for_each_cpu(i, cpu_map) {
2179                rq = cpu_rq(i);
2180                sd = *per_cpu_ptr(d.sd, i);
2181
2182                /* Use READ_ONCE()/WRITE_ONCE() to avoid load/store tearing: */
2183                if (rq->cpu_capacity_orig > READ_ONCE(d.rd->max_cpu_capacity))
2184                        WRITE_ONCE(d.rd->max_cpu_capacity, rq->cpu_capacity_orig);
2185
2186                cpu_attach_domain(sd, d.rd, i);
2187        }
2188        rcu_read_unlock();
2189
2190        if (has_asym)
2191                static_branch_inc_cpuslocked(&sched_asym_cpucapacity);
2192
2193        if (rq && sched_debug_verbose) {
2194                pr_info("root domain span: %*pbl (max cpu_capacity = %lu)\n",
2195                        cpumask_pr_args(cpu_map), rq->rd->max_cpu_capacity);
2196        }
2197
2198        ret = 0;
2199error:
2200        __free_domain_allocs(&d, alloc_state, cpu_map);
2201
2202        return ret;
2203}
2204
2205/* Current sched domains: */
2206static cpumask_var_t                    *doms_cur;
2207
2208/* Number of sched domains in 'doms_cur': */
2209static int                              ndoms_cur;
2210
2211/* Attributes of custom domains in 'doms_cur' */
2212static struct sched_domain_attr         *dattr_cur;
2213
2214/*
2215 * Special case: If a kmalloc() of a doms_cur partition (array of
2216 * cpumask) fails, then fallback to a single sched domain,
2217 * as determined by the single cpumask fallback_doms.
2218 */
2219static cpumask_var_t                    fallback_doms;
2220
2221/*
2222 * arch_update_cpu_topology lets virtualized architectures update the
2223 * CPU core maps. It is supposed to return 1 if the topology changed
2224 * or 0 if it stayed the same.
2225 */
2226int __weak arch_update_cpu_topology(void)
2227{
2228        return 0;
2229}
2230
2231cpumask_var_t *alloc_sched_domains(unsigned int ndoms)
2232{
2233        int i;
2234        cpumask_var_t *doms;
2235
2236        doms = kmalloc_array(ndoms, sizeof(*doms), GFP_KERNEL);
2237        if (!doms)
2238                return NULL;
2239        for (i = 0; i < ndoms; i++) {
2240                if (!alloc_cpumask_var(&doms[i], GFP_KERNEL)) {
2241                        free_sched_domains(doms, i);
2242                        return NULL;
2243                }
2244        }
2245        return doms;
2246}
2247
2248void free_sched_domains(cpumask_var_t doms[], unsigned int ndoms)
2249{
2250        unsigned int i;
2251        for (i = 0; i < ndoms; i++)
2252                free_cpumask_var(doms[i]);
2253        kfree(doms);
2254}
2255
2256/*
2257 * Set up scheduler domains and groups.  For now this just excludes isolated
2258 * CPUs, but could be used to exclude other special cases in the future.
2259 */
2260int sched_init_domains(const struct cpumask *cpu_map)
2261{
2262        int err;
2263
2264        zalloc_cpumask_var(&sched_domains_tmpmask, GFP_KERNEL);
2265        zalloc_cpumask_var(&sched_domains_tmpmask2, GFP_KERNEL);
2266        zalloc_cpumask_var(&fallback_doms, GFP_KERNEL);
2267
2268        arch_update_cpu_topology();
2269        asym_cpu_capacity_scan();
2270        ndoms_cur = 1;
2271        doms_cur = alloc_sched_domains(ndoms_cur);
2272        if (!doms_cur)
2273                doms_cur = &fallback_doms;
2274        cpumask_and(doms_cur[0], cpu_map, housekeeping_cpumask(HK_FLAG_DOMAIN));
2275        err = build_sched_domains(doms_cur[0], NULL);
2276
2277        return err;
2278}
2279
2280/*
2281 * Detach sched domains from a group of CPUs specified in cpu_map
2282 * These CPUs will now be attached to the NULL domain
2283 */
2284static void detach_destroy_domains(const struct cpumask *cpu_map)
2285{
2286        unsigned int cpu = cpumask_any(cpu_map);
2287        int i;
2288
2289        if (rcu_access_pointer(per_cpu(sd_asym_cpucapacity, cpu)))
2290                static_branch_dec_cpuslocked(&sched_asym_cpucapacity);
2291
2292        rcu_read_lock();
2293        for_each_cpu(i, cpu_map)
2294                cpu_attach_domain(NULL, &def_root_domain, i);
2295        rcu_read_unlock();
2296}
2297
2298/* handle null as "default" */
2299static int dattrs_equal(struct sched_domain_attr *cur, int idx_cur,
2300                        struct sched_domain_attr *new, int idx_new)
2301{
2302        struct sched_domain_attr tmp;
2303
2304        /* Fast path: */
2305        if (!new && !cur)
2306                return 1;
2307
2308        tmp = SD_ATTR_INIT;
2309
2310        return !memcmp(cur ? (cur + idx_cur) : &tmp,
2311                        new ? (new + idx_new) : &tmp,
2312                        sizeof(struct sched_domain_attr));
2313}
2314
2315/*
2316 * Partition sched domains as specified by the 'ndoms_new'
2317 * cpumasks in the array doms_new[] of cpumasks. This compares
2318 * doms_new[] to the current sched domain partitioning, doms_cur[].
2319 * It destroys each deleted domain and builds each new domain.
2320 *
2321 * 'doms_new' is an array of cpumask_var_t's of length 'ndoms_new'.
2322 * The masks don't intersect (don't overlap.) We should setup one
2323 * sched domain for each mask. CPUs not in any of the cpumasks will
2324 * not be load balanced. If the same cpumask appears both in the
2325 * current 'doms_cur' domains and in the new 'doms_new', we can leave
2326 * it as it is.
2327 *
2328 * The passed in 'doms_new' should be allocated using
2329 * alloc_sched_domains.  This routine takes ownership of it and will
2330 * free_sched_domains it when done with it. If the caller failed the
2331 * alloc call, then it can pass in doms_new == NULL && ndoms_new == 1,
2332 * and partition_sched_domains() will fallback to the single partition
2333 * 'fallback_doms', it also forces the domains to be rebuilt.
2334 *
2335 * If doms_new == NULL it will be replaced with cpu_online_mask.
2336 * ndoms_new == 0 is a special case for destroying existing domains,
2337 * and it will not create the default domain.
2338 *
2339 * Call with hotplug lock and sched_domains_mutex held
2340 */
2341void partition_sched_domains_locked(int ndoms_new, cpumask_var_t doms_new[],
2342                                    struct sched_domain_attr *dattr_new)
2343{
2344        bool __maybe_unused has_eas = false;
2345        int i, j, n;
2346        int new_topology;
2347
2348        lockdep_assert_held(&sched_domains_mutex);
2349
2350        /* Let the architecture update CPU core mappings: */
2351        new_topology = arch_update_cpu_topology();
2352        /* Trigger rebuilding CPU capacity asymmetry data */
2353        if (new_topology)
2354                asym_cpu_capacity_scan();
2355
2356        if (!doms_new) {
2357                WARN_ON_ONCE(dattr_new);
2358                n = 0;
2359                doms_new = alloc_sched_domains(1);
2360                if (doms_new) {
2361                        n = 1;
2362                        cpumask_and(doms_new[0], cpu_active_mask,
2363                                    housekeeping_cpumask(HK_FLAG_DOMAIN));
2364                }
2365        } else {
2366                n = ndoms_new;
2367        }
2368
2369        /* Destroy deleted domains: */
2370        for (i = 0; i < ndoms_cur; i++) {
2371                for (j = 0; j < n && !new_topology; j++) {
2372                        if (cpumask_equal(doms_cur[i], doms_new[j]) &&
2373                            dattrs_equal(dattr_cur, i, dattr_new, j)) {
2374                                struct root_domain *rd;
2375
2376                                /*
2377                                 * This domain won't be destroyed and as such
2378                                 * its dl_bw->total_bw needs to be cleared.  It
2379                                 * will be recomputed in function
2380                                 * update_tasks_root_domain().
2381                                 */
2382                                rd = cpu_rq(cpumask_any(doms_cur[i]))->rd;
2383                                dl_clear_root_domain(rd);
2384                                goto match1;
2385                        }
2386                }
2387                /* No match - a current sched domain not in new doms_new[] */
2388                detach_destroy_domains(doms_cur[i]);
2389match1:
2390                ;
2391        }
2392
2393        n = ndoms_cur;
2394        if (!doms_new) {
2395                n = 0;
2396                doms_new = &fallback_doms;
2397                cpumask_and(doms_new[0], cpu_active_mask,
2398                            housekeeping_cpumask(HK_FLAG_DOMAIN));
2399        }
2400
2401        /* Build new domains: */
2402        for (i = 0; i < ndoms_new; i++) {
2403                for (j = 0; j < n && !new_topology; j++) {
2404                        if (cpumask_equal(doms_new[i], doms_cur[j]) &&
2405                            dattrs_equal(dattr_new, i, dattr_cur, j))
2406                                goto match2;
2407                }
2408                /* No match - add a new doms_new */
2409                build_sched_domains(doms_new[i], dattr_new ? dattr_new + i : NULL);
2410match2:
2411                ;
2412        }
2413
2414#if defined(CONFIG_ENERGY_MODEL) && defined(CONFIG_CPU_FREQ_GOV_SCHEDUTIL)
2415        /* Build perf. domains: */
2416        for (i = 0; i < ndoms_new; i++) {
2417                for (j = 0; j < n && !sched_energy_update; j++) {
2418                        if (cpumask_equal(doms_new[i], doms_cur[j]) &&
2419                            cpu_rq(cpumask_first(doms_cur[j]))->rd->pd) {
2420                                has_eas = true;
2421                                goto match3;
2422                        }
2423                }
2424                /* No match - add perf. domains for a new rd */
2425                has_eas |= build_perf_domains(doms_new[i]);
2426match3:
2427                ;
2428        }
2429        sched_energy_set(has_eas);
2430#endif
2431
2432        /* Remember the new sched domains: */
2433        if (doms_cur != &fallback_doms)
2434                free_sched_domains(doms_cur, ndoms_cur);
2435
2436        kfree(dattr_cur);
2437        doms_cur = doms_new;
2438        dattr_cur = dattr_new;
2439        ndoms_cur = ndoms_new;
2440
2441        update_sched_domain_debugfs();
2442}
2443
2444/*
2445 * Call with hotplug lock held
2446 */
2447void partition_sched_domains(int ndoms_new, cpumask_var_t doms_new[],
2448                             struct sched_domain_attr *dattr_new)
2449{
2450        mutex_lock(&sched_domains_mutex);
2451        partition_sched_domains_locked(ndoms_new, doms_new, dattr_new);
2452        mutex_unlock(&sched_domains_mutex);
2453}
2454
lxr.linux.no kindly hosted by Redpill Linpro AS, provider of Linux consulting and operations services since 1995.