// SPDX-License-Identifier: GPL-2.0 /* * Scheduler topology setup/handling methods */ #include #include #include "sched.h" DEFINE_MUTEX(sched_domains_mutex); /* Protected by sched_domains_mutex: */ cpumask_var_t sched_domains_tmpmask; cpumask_var_t sched_domains_tmpmask2; #ifdef CONFIG_SCHED_DEBUG static int __init sched_debug_setup(char *str) { sched_debug_enabled = true; return 0; } early_param("sched_debug", sched_debug_setup); static inline bool sched_debug(void) { return sched_debug_enabled; } static int sched_domain_debug_one(struct sched_domain *sd, int cpu, int level, struct cpumask *groupmask) { struct sched_group *group = sd->groups; cpumask_clear(groupmask); printk(KERN_DEBUG "%*s domain-%d: ", level, "", level); if (!(sd->flags & SD_LOAD_BALANCE)) { printk("does not load-balance\n"); if (sd->parent) printk(KERN_ERR "ERROR: !SD_LOAD_BALANCE domain" " has parent"); return -1; } printk(KERN_CONT "span=%*pbl level=%s\n", cpumask_pr_args(sched_domain_span(sd)), sd->name); if (!cpumask_test_cpu(cpu, sched_domain_span(sd))) { printk(KERN_ERR "ERROR: domain->span does not contain " "CPU%d\n", cpu); } if (!cpumask_test_cpu(cpu, sched_group_span(group))) { printk(KERN_ERR "ERROR: domain->groups does not contain" " CPU%d\n", cpu); } printk(KERN_DEBUG "%*s groups:", level + 1, ""); do { if (!group) { printk("\n"); printk(KERN_ERR "ERROR: group is NULL\n"); break; } if (!cpumask_weight(sched_group_span(group))) { printk(KERN_CONT "\n"); printk(KERN_ERR "ERROR: empty group\n"); break; } if (!(sd->flags & SD_OVERLAP) && cpumask_intersects(groupmask, sched_group_span(group))) { printk(KERN_CONT "\n"); printk(KERN_ERR "ERROR: repeated CPUs\n"); break; } cpumask_or(groupmask, groupmask, sched_group_span(group)); printk(KERN_CONT " %d:{ span=%*pbl", group->sgc->id, cpumask_pr_args(sched_group_span(group))); if ((sd->flags & SD_OVERLAP) && !cpumask_equal(group_balance_mask(group), sched_group_span(group))) { printk(KERN_CONT " mask=%*pbl", cpumask_pr_args(group_balance_mask(group))); } if (group->sgc->capacity != SCHED_CAPACITY_SCALE) printk(KERN_CONT " cap=%lu", group->sgc->capacity); if (group == sd->groups && sd->child && !cpumask_equal(sched_domain_span(sd->child), sched_group_span(group))) { printk(KERN_ERR "ERROR: domain->groups does not match domain->child\n"); } printk(KERN_CONT " }"); group = group->next; if (group != sd->groups) printk(KERN_CONT ","); } while (group != sd->groups); printk(KERN_CONT "\n"); if (!cpumask_equal(sched_domain_span(sd), groupmask)) printk(KERN_ERR "ERROR: groups don't span domain->span\n"); if (sd->parent && !cpumask_subset(groupmask, sched_domain_span(sd->parent))) printk(KERN_ERR "ERROR: parent span is not a superset " "of domain->span\n"); return 0; } static void sched_domain_debug(struct sched_domain *sd, int cpu) { int level = 0; if (!sched_debug_enabled) return; if (!sd) { printk(KERN_DEBUG "CPU%d attaching NULL sched-domain.\n", cpu); return; } printk(KERN_DEBUG "CPU%d attaching sched-domain(s):\n", cpu); for (;;) { if (sched_domain_debug_one(sd, cpu, level, sched_domains_tmpmask)) break; level++; sd = sd->parent; if (!sd) break; } } #else /* !CONFIG_SCHED_DEBUG */ # define sched_debug_enabled 0 # define sched_domain_debug(sd, cpu) do { } while (0) static inline bool sched_debug(void) { return false; } #endif /* CONFIG_SCHED_DEBUG */ static int sd_degenerate(struct sched_domain *sd) { if (cpumask_weight(sched_domain_span(sd)) == 1) return 1; /* Following flags need at least 2 groups */ if (sd->flags & (SD_LOAD_BALANCE | SD_BALANCE_NEWIDLE | SD_BALANCE_FORK | SD_BALANCE_EXEC | SD_SHARE_CPUCAPACITY | SD_ASYM_CPUCAPACITY | SD_SHARE_PKG_RESOURCES | SD_SHARE_POWERDOMAIN)) { if (sd->groups != sd->groups->next) return 0; } /* Following flags don't use groups */ if (sd->flags & (SD_WAKE_AFFINE)) return 0; return 1; } static int sd_parent_degenerate(struct sched_domain *sd, struct sched_domain *parent) { unsigned long cflags = sd->flags, pflags = parent->flags; if (sd_degenerate(parent)) return 1; if (!cpumask_equal(sched_domain_span(sd), sched_domain_span(parent))) return 0; /* Flags needing groups don't count if only 1 group in parent */ if (parent->groups == parent->groups->next) { pflags &= ~(SD_LOAD_BALANCE | SD_BALANCE_NEWIDLE | SD_BALANCE_FORK | SD_BALANCE_EXEC | SD_ASYM_CPUCAPACITY | SD_SHARE_CPUCAPACITY | SD_SHARE_PKG_RESOURCES | SD_PREFER_SIBLING | SD_SHARE_POWERDOMAIN); if (nr_node_ids == 1) pflags &= ~SD_SERIALIZE; } if (~cflags & pflags) return 0; return 1; } static void free_rootdomain(struct rcu_head *rcu) { struct root_domain *rd = container_of(rcu, struct root_domain, rcu); cpupri_cleanup(&rd->cpupri); cpudl_cleanup(&rd->cpudl); free_cpumask_var(rd->dlo_mask); free_cpumask_var(rd->rto_mask); free_cpumask_var(rd->online); free_cpumask_var(rd->span); kfree(rd); } void rq_attach_root(struct rq *rq, struct root_domain *rd) { struct root_domain *old_rd = NULL; unsigned long flags; raw_spin_lock_irqsave(&rq->lock, flags); if (rq->rd) { old_rd = rq->rd; if (cpumask_test_cpu(rq->cpu, old_rd->online)) set_rq_offline(rq); cpumask_clear_cpu(rq->cpu, old_rd->span); /* * If we dont want to free the old_rd yet then * set old_rd to NULL to skip the freeing later * in this function: */ if (!atomic_dec_and_test(&old_rd->refcount)) old_rd = NULL; } atomic_inc(&rd->refcount); rq->rd = rd; cpumask_set_cpu(rq->cpu, rd->span); if (cpumask_test_cpu(rq->cpu, cpu_active_mask)) set_rq_online(rq); raw_spin_unlock_irqrestore(&rq->lock, flags); if (old_rd) call_rcu_sched(&old_rd->rcu, free_rootdomain); } void sched_get_rd(struct root_domain *rd) { atomic_inc(&rd->refcount); } void sched_put_rd(struct root_domain *rd) { if (!atomic_dec_and_test(&rd->refcount)) return; call_rcu_sched(&rd->rcu, free_rootdomain); } static int init_rootdomain(struct root_domain *rd) { if (!zalloc_cpumask_var(&rd->span, GFP_KERNEL)) goto out; if (!zalloc_cpumask_var(&rd->online, GFP_KERNEL)) goto free_span; if (!zalloc_cpumask_var(&rd->dlo_mask, GFP_KERNEL)) goto free_online; if (!zalloc_cpumask_var(&rd->rto_mask, GFP_KERNEL)) goto free_dlo_mask; #ifdef HAVE_RT_PUSH_IPI rd->rto_cpu = -1; raw_spin_lock_init(&rd->rto_lock); init_irq_work(&rd->rto_push_work, rto_push_irq_work_func); #endif init_dl_bw(&rd->dl_bw); if (cpudl_init(&rd->cpudl) != 0) goto free_rto_mask; if (cpupri_init(&rd->cpupri) != 0) goto free_cpudl; return 0; free_cpudl: cpudl_cleanup(&rd->cpudl); free_rto_mask: free_cpumask_var(rd->rto_mask); free_dlo_mask: free_cpumask_var(rd->dlo_mask); free_online: free_cpumask_var(rd->online); free_span: free_cpumask_var(rd->span); out: return -ENOMEM; } /* * By default the system creates a single root-domain with all CPUs as * members (mimicking the global state we have today). */ struct root_domain def_root_domain; void init_defrootdomain(void) { init_rootdomain(&def_root_domain); atomic_set(&def_root_domain.refcount, 1); } static struct root_domain *alloc_rootdomain(void) { struct root_domain *rd; rd = kzalloc(sizeof(*rd), GFP_KERNEL); if (!rd) return NULL; if (init_rootdomain(rd) != 0) { kfree(rd); return NULL; } return rd; } static void free_sched_groups(struct sched_group *sg, int free_sgc) { struct sched_group *tmp, *first; if (!sg) return; first = sg; do { tmp = sg->next; if (free_sgc && atomic_dec_and_test(&sg->sgc->ref)) kfree(sg->sgc); if (atomic_dec_and_test(&sg->ref)) kfree(sg); sg = tmp; } while (sg != first); } static void destroy_sched_domain(struct sched_domain *sd) { /* * A normal sched domain may have multiple group references, an * overlapping domain, having private groups, only one. Iterate, * dropping group/capacity references, freeing where none remain. */ free_sched_groups(sd->groups, 1); if (sd->shared && atomic_dec_and_test(&sd->shared->ref)) kfree(sd->shared); kfree(sd); } static void destroy_sched_domains_rcu(struct rcu_head *rcu) { struct sched_domain *sd = container_of(rcu, struct sched_domain, rcu); while (sd) { struct sched_domain *parent = sd->parent; destroy_sched_domain(sd); sd = parent; } } static void destroy_sched_domains(struct sched_domain *sd) { if (sd) call_rcu(&sd->rcu, destroy_sched_domains_rcu); } /* * Keep a special pointer to the highest sched_domain that has * SD_SHARE_PKG_RESOURCE set (Last Level Cache Domain) for this * allows us to avoid some pointer chasing select_idle_sibling(). * * Also keep a unique ID per domain (we use the first CPU number in * the cpumask of the domain), this allows us to quickly tell if * two CPUs are in the same cache domain, see cpus_share_cache(). */ DEFINE_PER_CPU(struct sched_domain *, sd_llc); DEFINE_PER_CPU(int, sd_llc_size); DEFINE_PER_CPU(int, sd_llc_id); DEFINE_PER_CPU(struct sched_domain_shared *, sd_llc_shared); DEFINE_PER_CPU(struct sched_domain *, sd_numa); DEFINE_PER_CPU(struct sched_domain *, sd_asym); static void update_top_cache_domain(int cpu) { struct sched_domain_shared *sds = NULL; struct sched_domain *sd; int id = cpu; int size = 1; sd = highest_flag_domain(cpu, SD_SHARE_PKG_RESOURCES); if (sd) { id = cpumask_first(sched_domain_span(sd)); size = cpumask_weight(sched_domain_span(sd)); sds = sd->shared; } rcu_assign_pointer(per_cpu(sd_llc, cpu), sd); per_cpu(sd_llc_size, cpu) = size; per_cpu(sd_llc_id, cpu) = id; rcu_assign_pointer(per_cpu(sd_llc_shared, cpu), sds); sd = lowest_flag_domain(cpu, SD_NUMA); rcu_assign_pointer(per_cpu(sd_numa, cpu), sd); sd = highest_flag_domain(cpu, SD_ASYM_PACKING); rcu_assign_pointer(per_cpu(sd_asym, cpu), sd); } /* * Attach the domain 'sd' to 'cpu' as its base domain. Callers must * hold the hotplug lock. */ static void cpu_attach_domain(struct sched_domain *sd, struct root_domain *rd, int cpu) { struct rq *rq = cpu_rq(cpu); struct sched_domain *tmp; /* Remove the sched domains which do not contribute to scheduling. */ for (tmp = sd; tmp; ) { struct sched_domain *parent = tmp->parent; if (!parent) break; if (sd_parent_degenerate(tmp, parent)) { tmp->parent = parent->parent; if (parent->parent) parent->parent->child = tmp; /* * Transfer SD_PREFER_SIBLING down in case of a * degenerate parent; the spans match for this * so the property transfers. */ if (parent->flags & SD_PREFER_SIBLING) tmp->flags |= SD_PREFER_SIBLING; destroy_sched_domain(parent); } else tmp = tmp->parent; } if (sd && sd_degenerate(sd)) { tmp = sd; sd = sd->parent; destroy_sched_domain(tmp); if (sd) sd->child = NULL; } sched_domain_debug(sd, cpu); rq_attach_root(rq, rd); tmp = rq->sd; rcu_assign_pointer(rq->sd, sd); dirty_sched_domain_sysctl(cpu); destroy_sched_domains(tmp); update_top_cache_domain(cpu); } /* Setup the mask of CPUs configured for isolated domains */ static int __init isolated_cpu_setup(char *str) { int ret; alloc_bootmem_cpumask_var(&cpu_isolated_map); ret = cpulist_parse(str, cpu_isolated_map); if (ret) { pr_err("sched: Error, all isolcpus= values must be between 0 and %u\n", nr_cpu_ids); return 0; } return 1; } __setup("isolcpus=", isolated_cpu_setup); struct s_data { struct sched_domain * __percpu *sd; struct root_domain *rd; }; enum s_alloc { sa_rootdomain, sa_sd, sa_sd_storage, sa_none, }; /* * Return the canonical balance CPU for this group, this is the first CPU * of this group that's also in the balance mask. * * The balance mask are all those CPUs that could actually end up at this * group. See build_balance_mask(). * * Also see should_we_balance(). */ int group_balance_cpu(struct sched_group *sg) { return cpumask_first(group_balance_mask(sg)); } /* * NUMA topology (first read the regular topology blurb below) * * Given a node-distance table, for example: * * node 0 1 2 3 * 0: 10 20 30 20 * 1: 20 10 20 30 * 2: 30 20 10 20 * 3: 20 30 20 10 * * which represents a 4 node ring topology like: * * 0 ----- 1 * | | * | | * | | * 3 ----- 2 * * We want to construct domains and groups to represent this. The way we go * about doing this is to build the domains on 'hops'. For each NUMA level we * construct the mask of all nodes reachable in @level hops. * * For the above NUMA topology that gives 3 levels: * * NUMA-2 0-3 0-3 0-3 0-3 * groups: {0-1,3},{1-3} {0-2},{0,2-3} {1-3},{0-1,3} {0,2-3},{0-2} * * NUMA-1 0-1,3 0-2 1-3 0,2-3 * groups: {0},{1},{3} {0},{1},{2} {1},{2},{3} {0},{2},{3} * * NUMA-0 0 1 2 3 * * * As can be seen; things don't nicely line up as with the regular topology. * When we iterate a domain in child domain chunks some nodes can be * represented multiple times -- hence the "overlap" naming for this part of * the topology. * * In order to minimize this overlap, we only build enough groups to cover the * domain. For instance Node-0 NUMA-2 would only get groups: 0-1,3 and 1-3. * * Because: * * - the first group of each domain is its child domain; this * gets us the first 0-1,3 * - the only uncovered node is 2, who's child domain is 1-3. * * However, because of the overlap, computing a unique CPU for each group is * more complicated. Consider for instance the groups of NODE-1 NUMA-2, both * groups include the CPUs of Node-0, while those CPUs would not in fact ever * end up at those groups (they would end up in group: 0-1,3). * * To correct this we have to introduce the group balance mask. This mask * will contain those CPUs in the group that can reach this group given the * (child) domain tree. * * With this we can once again compute balance_cpu and sched_group_capacity * relations. * * XXX include words on how balance_cpu is unique and therefore can be * used for sched_group_capacity links. * * * Another 'interesting' topology is: * * node 0 1 2 3 * 0: 10 20 20 30 * 1: 20 10 20 20 * 2: 20 20 10 20 * 3: 30 20 20 10 * * Which looks a little like: * * 0 ----- 1 * | / | * | / | * | / | * 2 ----- 3 * * This topology is asymmetric, nodes 1,2 are fully connected, but nodes 0,3 * are not. * * This leads to a few particularly weird cases where the sched_domain's are * not of the same number for each cpu. Consider: * * NUMA-2 0-3 0-3 * groups: {0-2},{1-3} {1-3},{0-2} * * NUMA-1 0-2 0-3 0-3 1-3 * * NUMA-0 0 1 2 3 * */ /* * Build the balance mask; it contains only those CPUs that can arrive at this * group and should be considered to continue balancing. * * We do this during the group creation pass, therefore the group information * isn't complete yet, however since each group represents a (child) domain we * can fully construct this using the sched_domain bits (which are already * complete). */ static void build_balance_mask(struct sched_domain *sd, struct sched_group *sg, struct cpumask *mask) { const struct cpumask *sg_span = sched_group_span(sg); struct sd_data *sdd = sd->private; struct sched_domain *sibling; int i; cpumask_clear(mask); for_each_cpu(i, sg_span) { sibling = *per_cpu_ptr(sdd->sd, i); /* * Can happen in the asymmetric case, where these siblings are * unused. The mask will not be empty because those CPUs that * do have the top domain _should_ span the domain. */ if (!sibling->child) continue; /* If we would not end up here, we can't continue from here */ if (!cpumask_equal(sg_span, sched_domain_span(sibling->child))) continue; cpumask_set_cpu(i, mask); } /* We must not have empty masks here */ WARN_ON_ONCE(cpumask_empty(mask)); } /* * XXX: This creates per-node group entries; since the load-balancer will * immediately access remote memory to construct this group's load-balance * statistics having the groups node local is of dubious benefit. */ static struct sched_group * build_group_from_child_sched_domain(struct sched_domain *sd, int cpu) { struct sched_group *sg; struct cpumask *sg_span; sg = kzalloc_node(sizeof(struct sched_group) + cpumask_size(), GFP_KERNEL, cpu_to_node(cpu)); if (!sg) return NULL; sg_span = sched_group_span(sg); if (sd->child) cpumask_copy(sg_span, sched_domain_span(sd->child)); else cpumask_copy(sg_span, sched_domain_span(sd)); atomic_inc(&sg->ref); return sg; } static void init_overlap_sched_group(struct sched_domain *sd, struct sched_group *sg) { struct cpumask *mask = sched_domains_tmpmask2; struct sd_data *sdd = sd->private; struct cpumask *sg_span; int cpu; build_balance_mask(sd, sg, mask); cpu = cpumask_first_and(sched_group_span(sg), mask); sg->sgc = *per_cpu_ptr(sdd->sgc, cpu); if (atomic_inc_return(&sg->sgc->ref) == 1) cpumask_copy(group_balance_mask(sg), mask); else WARN_ON_ONCE(!cpumask_equal(group_balance_mask(sg), mask)); /* * Initialize sgc->capacity such that even if we mess up the * domains and no possible iteration will get us here, we won't * die on a /0 trap. */ sg_span = sched_group_span(sg); sg->sgc->capacity = SCHED_CAPACITY_SCALE * cpumask_weight(sg_span); sg->sgc->min_capacity = SCHED_CAPACITY_SCALE; } static int build_overlap_sched_groups(struct sched_domain *sd, int cpu) { struct sched_group *first = NULL, *last = NULL, *sg; const struct cpumask *span = sched_domain_span(sd); struct cpumask *covered = sched_domains_tmpmask; struct sd_data *sdd = sd->private; struct sched_domain *sibling; int i; cpumask_clear(covered); for_each_cpu_wrap(i, span, cpu) { struct cpumask *sg_span; if (cpumask_test_cpu(i, covered)) continue; sibling = *per_cpu_ptr(sdd->sd, i); /* * Asymmetric node setups can result in situations where the * domain tree is of unequal depth, make sure to skip domains * that already cover the entire range. * * In that case build_sched_domains() will have terminated the * iteration early and our sibling sd spans will be empty. * Domains should always include the CPU they're built on, so * check that. */ if (!cpumask_test_cpu(i, sched_domain_span(sibling))) continue; sg = build_group_from_child_sched_domain(sibling, cpu); if (!sg) goto fail; sg_span = sched_group_span(sg); cpumask_or(covered, covered, sg_span); init_overlap_sched_group(sd, sg); if (!first) first = sg; if (last) last->next = sg; last = sg; last->next = first; } sd->groups = first; return 0; fail: free_sched_groups(first, 0); return -ENOMEM; } /* * Package topology (also see the load-balance blurb in fair.c) * * The scheduler builds a tree structure to represent a number of important * topology features. By default (default_topology[]) these include: * * - Simultaneous multithreading (SMT) * - Multi-Core Cache (MC) * - Package (DIE) * * Where the last one more or less denotes everything up to a NUMA node. * * The tree consists of 3 primary data structures: * * sched_domain -> sched_group -> sched_group_capacity * ^ ^ ^ ^ * `-' `-' * * The sched_domains are per-cpu and have a two way link (parent & child) and * denote the ever growing mask of CPUs belonging to that level of topology. * * Each sched_domain has a circular (double) linked list of sched_group's, each * denoting the domains of the level below (or individual CPUs in case of the * first domain level). The sched_group linked by a sched_domain includes the * CPU of that sched_domain [*]. * * Take for instance a 2 threaded, 2 core, 2 cache cluster part: * * CPU 0 1 2 3 4 5 6 7 * * DIE [ ] * MC [ ] [ ] * SMT [ ] [ ] [ ] [ ] * * - or - * * DIE 0-7 0-7 0-7 0-7 0-7 0-7 0-7 0-7 * MC 0-3 0-3 0-3 0-3 4-7 4-7 4-7 4-7 * SMT 0-1 0-1 2-3 2-3 4-5 4-5 6-7 6-7 * * CPU 0 1 2 3 4 5 6 7 * * One way to think about it is: sched_domain moves you up and down among these * topology levels, while sched_group moves you sideways through it, at child * domain granularity. * * sched_group_capacity ensures each unique sched_group has shared storage. * * There are two related construction problems, both require a CPU that * uniquely identify each group (for a given domain): * * - The first is the balance_cpu (see should_we_balance() and the * load-balance blub in fair.c); for each group we only want 1 CPU to * continue balancing at a higher domain. * * - The second is the sched_group_capacity; we want all identical groups * to share a single sched_group_capacity. * * Since these topologies are exclusive by construction. That is, its * impossible for an SMT thread to belong to multiple cores, and cores to * be part of multiple caches. There is a very clear and unique location * for each CPU in the hierarchy. * * Therefore computing a unique CPU for each group is trivial (the iteration * mask is redundant and set all 1s; all CPUs in a group will end up at _that_ * group), we can simply pick the first CPU in each group. * * * [*] in other words, the first group of each domain is its child domain. */ static struct sched_group *get_group(int cpu, struct sd_data *sdd) { struct sched_domain *sd = *per_cpu_ptr(sdd->sd, cpu); struct sched_domain *child = sd->child; struct sched_group *sg; if (child) cpu = cpumask_first(sched_domain_span(child)); sg = *per_cpu_ptr(sdd->sg, cpu); sg->sgc = *per_cpu_ptr(sdd->sgc, cpu); /* For claim_allocations: */ atomic_inc(&sg->ref); atomic_inc(&sg->sgc->ref); if (child) { cpumask_copy(sched_group_span(sg), sched_domain_span(child)); cpumask_copy(group_balance_mask(sg), sched_group_span(sg)); } else { cpumask_set_cpu(cpu, sched_group_span(sg)); cpumask_set_cpu(cpu, group_balance_mask(sg)); } sg->sgc->capacity = SCHED_CAPACITY_SCALE * cpumask_weight(sched_group_span(sg)); sg->sgc->min_capacity = SCHED_CAPACITY_SCALE; return sg; } /* * build_sched_groups will build a circular linked list of the groups * covered by the given span, and will set each group's ->cpumask correctly, * and ->cpu_capacity to 0. * * Assumes the sched_domain tree is fully constructed */ static int build_sched_groups(struct sched_domain *sd, int cpu) { struct sched_group *first = NULL, *last = NULL; struct sd_data *sdd = sd->private; const struct cpumask *span = sched_domain_span(sd); struct cpumask *covered; int i; lockdep_assert_held(&sched_domains_mutex); covered = sched_domains_tmpmask; cpumask_clear(covered); for_each_cpu_wrap(i, span, cpu) { struct sched_group *sg; if (cpumask_test_cpu(i, covered)) continue; sg = get_group(i, sdd); cpumask_or(covered, covered, sched_group_span(sg)); if (!first) first = sg; if (last) last->next = sg; last = sg; } last->next = first; sd->groups = first; return 0; } /* * Initialize sched groups cpu_capacity. * * cpu_capacity indicates the capacity of sched group, which is used while * distributing the load between different sched groups in a sched domain. * Typically cpu_capacity for all the groups in a sched domain will be same * unless there are asymmetries in the topology. If there are asymmetries, * group having more cpu_capacity will pickup more load compared to the * group having less cpu_capacity. */ static void init_sched_groups_capacity(int cpu, struct sched_domain *sd) { struct sched_group *sg = sd->groups; WARN_ON(!sg); do { int cpu, max_cpu = -1; sg->group_weight = cpumask_weight(sched_group_span(sg)); if (!(sd->flags & SD_ASYM_PACKING)) goto next; for_each_cpu(cpu, sched_group_span(sg)) { if (max_cpu < 0) max_cpu = cpu; else if (sched_asym_prefer(cpu, max_cpu)) max_cpu = cpu; } sg->asym_prefer_cpu = max_cpu; next: sg = sg->next; } while (sg != sd->groups); if (cpu != group_balance_cpu(sg)) return; update_group_capacity(sd, cpu); } /* * Initializers for schedule domains * Non-inlined to reduce accumulated stack pressure in build_sched_domains() */ static int default_relax_domain_level = -1; int sched_domain_level_max; static int __init setup_relax_domain_level(char *str) { if (kstrtoint(str, 0, &default_relax_domain_level)) pr_warn("Unable to set relax_domain_level\n"); return 1; } __setup("relax_domain_level=", setup_relax_domain_level); static void set_domain_attribute(struct sched_domain *sd, struct sched_domain_attr *attr) { int request; if (!attr || attr->relax_domain_level < 0) { if (default_relax_domain_level < 0) return; else request = default_relax_domain_level; } else request = attr->relax_domain_level; if (request < sd->level) { /* Turn off idle balance on this domain: */ sd->flags &= ~(SD_BALANCE_WAKE|SD_BALANCE_NEWIDLE); } else { /* Turn on idle balance on this domain: */ sd->flags |= (SD_BALANCE_WAKE|SD_BALANCE_NEWIDLE); } } static void __sdt_free(const struct cpumask *cpu_map); static int __sdt_alloc(const struct cpumask *cpu_map); static void __free_domain_allocs(struct s_data *d, enum s_alloc what, const struct cpumask *cpu_map) { switch (what) { case sa_rootdomain: if (!atomic_read(&d->rd->refcount)) free_rootdomain(&d->rd->rcu); /* Fall through */ case sa_sd: free_percpu(d->sd); /* Fall through */ case sa_sd_storage: __sdt_free(cpu_map); /* Fall through */ case sa_none: break; } } static enum s_alloc __visit_domain_allocation_hell(struct s_data *d, const struct cpumask *cpu_map) { memset(d, 0, sizeof(*d)); if (__sdt_alloc(cpu_map)) return sa_sd_storage; d->sd = alloc_percpu(struct sched_domain *); if (!d->sd) return sa_sd_storage; d->rd = alloc_rootdomain(); if (!d->rd) return sa_sd; return sa_rootdomain; } /* * NULL the sd_data elements we've used to build the sched_domain and * sched_group structure so that the subsequent __free_domain_allocs() * will not free the data we're using. */ static void claim_allocations(int cpu, struct sched_domain *sd) { struct sd_data *sdd = sd->private; WARN_ON_ONCE(*per_cpu_ptr(sdd->sd, cpu) != sd); *per_cpu_ptr(sdd->sd, cpu) = NULL; if (atomic_read(&(*per_cpu_ptr(sdd->sds, cpu))->ref)) *per_cpu_ptr(sdd->sds, cpu) = NULL; if (atomic_read(&(*per_cpu_ptr(sdd->sg, cpu))->ref)) *per_cpu_ptr(sdd->sg, cpu) = NULL; if (atomic_read(&(*per_cpu_ptr(sdd->sgc, cpu))->ref)) *per_cpu_ptr(sdd->sgc, cpu) = NULL; } #ifdef CONFIG_NUMA static int sched_domains_numa_levels; enum numa_topology_type sched_numa_topology_type; static int *sched_domains_numa_distance; int sched_max_numa_distance; static struct cpumask ***sched_domains_numa_masks; static int sched_domains_curr_level; #endif /* * SD_flags allowed in topology descriptions. * * These flags are purely descriptive of the topology and do not prescribe * behaviour. Behaviour is artificial and mapped in the below sd_init() * function: * * SD_SHARE_CPUCAPACITY - describes SMT topologies * SD_SHARE_PKG_RESOURCES - describes shared caches * SD_NUMA - describes NUMA topologies * SD_SHARE_POWERDOMAIN - describes shared power domain * SD_ASYM_CPUCAPACITY - describes mixed capacity topologies * * Odd one out, which beside describing the topology has a quirk also * prescribes the desired behaviour that goes along with it: * * SD_ASYM_PACKING - describes SMT quirks */ #define TOPOLOGY_SD_FLAGS \ (SD_SHARE_CPUCAPACITY | \ SD_SHARE_PKG_RESOURCES | \ SD_NUMA | \ SD_ASYM_PACKING | \ SD_ASYM_CPUCAPACITY | \ SD_SHARE_POWERDOMAIN) static struct sched_domain * sd_init(struct sched_domain_topology_level *tl, const struct cpumask *cpu_map, struct sched_domain *child, int cpu) { struct sd_data *sdd = &tl->data; struct sched_domain *sd = *per_cpu_ptr(sdd->sd, cpu); int sd_id, sd_weight, sd_flags = 0; #ifdef CONFIG_NUMA /* * Ugly hack to pass state to sd_numa_mask()... */ sched_domains_curr_level = tl->numa_level; #endif sd_weight = cpumask_weight(tl->mask(cpu)); if (tl->sd_flags) sd_flags = (*tl->sd_flags)(); if (WARN_ONCE(sd_flags & ~TOPOLOGY_SD_FLAGS, "wrong sd_flags in topology description\n")) sd_flags &= TOPOLOGY_SD_FLAGS; *sd = (struct sched_domain){ .min_interval = sd_weight, .max_interval = 2*sd_weight, .busy_factor = 32, .imbalance_pct = 125, .cache_nice_tries = 0, .busy_idx = 0, .idle_idx = 0, .newidle_idx = 0, .wake_idx = 0, .forkexec_idx = 0, .flags = 1*SD_LOAD_BALANCE | 1*SD_BALANCE_NEWIDLE | 1*SD_BALANCE_EXEC | 1*SD_BALANCE_FORK | 0*SD_BALANCE_WAKE | 1*SD_WAKE_AFFINE | 0*SD_SHARE_CPUCAPACITY | 0*SD_SHARE_PKG_RESOURCES | 0*SD_SERIALIZE | 0*SD_PREFER_SIBLING | 0*SD_NUMA | sd_flags , .last_balance = jiffies, .balance_interval = sd_weight, .smt_gain = 0, .max_newidle_lb_cost = 0, .next_decay_max_lb_cost = jiffies, .child = child, #ifdef CONFIG_SCHED_DEBUG .name = tl->name, #endif }; cpumask_and(sched_domain_span(sd), cpu_map, tl->mask(cpu)); sd_id = cpumask_first(sched_domain_span(sd)); /* * Convert topological properties into behaviour. */ if (sd->flags & SD_ASYM_CPUCAPACITY) { struct sched_domain *t = sd; for_each_lower_domain(t) t->flags |= SD_BALANCE_WAKE; } if (sd->flags & SD_SHARE_CPUCAPACITY) { sd->flags |= SD_PREFER_SIBLING; sd->imbalance_pct = 110; sd->smt_gain = 1178; /* ~15% */ } else if (sd->flags & SD_SHARE_PKG_RESOURCES) { sd->imbalance_pct = 117; sd->cache_nice_tries = 1; sd->busy_idx = 2; #ifdef CONFIG_NUMA } else if (sd->flags & SD_NUMA) { sd->cache_nice_tries = 2; sd->busy_idx = 3; sd->idle_idx = 2; sd->flags |= SD_SERIALIZE; if (sched_domains_numa_distance[tl->numa_level] > RECLAIM_DISTANCE) { sd->flags &= ~(SD_BALANCE_EXEC | SD_BALANCE_FORK | SD_WAKE_AFFINE); } #endif } else { sd->flags |= SD_PREFER_SIBLING; sd->cache_nice_tries = 1; sd->busy_idx = 2; sd->idle_idx = 1; } /* * For all levels sharing cache; connect a sched_domain_shared * instance. */ if (sd->flags & SD_SHARE_PKG_RESOURCES) { sd->shared = *per_cpu_ptr(sdd->sds, sd_id); atomic_inc(&sd->shared->ref); atomic_set(&sd->shared->nr_busy_cpus, sd_weight); } sd->private = sdd; return sd; } /* * Topology list, bottom-up. */ static struct sched_domain_topology_level default_topology[] = { #ifdef CONFIG_SCHED_SMT { cpu_smt_mask, cpu_smt_flags, SD_INIT_NAME(SMT) }, #endif #ifdef CONFIG_SCHED_MC { cpu_coregroup_mask, cpu_core_flags, SD_INIT_NAME(MC) }, #endif { cpu_cpu_mask, SD_INIT_NAME(DIE) }, { NULL, }, }; static struct sched_domain_topology_level *sched_domain_topology = default_topology; #define for_each_sd_topology(tl) \ for (tl = sched_domain_topology; tl->mask; tl++) void set_sched_topology(struct sched_domain_topology_level *tl) { if (WARN_ON_ONCE(sched_smp_initialized)) return; sched_domain_topology = tl; } #ifdef CONFIG_NUMA static const struct cpumask *sd_numa_mask(int cpu) { return sched_domains_numa_masks[sched_domains_curr_level][cpu_to_node(cpu)]; } static void sched_numa_warn(const char *str) { static int done = false; int i,j; if (done) return; done = true; printk(KERN_WARNING "ERROR: %s\n\n", str); for (i = 0; i < nr_node_ids; i++) { printk(KERN_WARNING " "); for (j = 0; j < nr_node_ids; j++) printk(KERN_CONT "%02d ", node_distance(i,j)); printk(KERN_CONT "\n"); } printk(KERN_WARNING "\n"); } bool find_numa_distance(int distance) { int i; if (distance == node_distance(0, 0)) return true; for (i = 0; i < sched_domains_numa_levels; i++) { if (sched_domains_numa_distance[i] == distance) return true; } return false; } /* * A system can have three types of NUMA topology: * NUMA_DIRECT: all nodes are directly connected, or not a NUMA system * NUMA_GLUELESS_MESH: some nodes reachable through intermediary nodes * NUMA_BACKPLANE: nodes can reach other nodes through a backplane * * The difference between a glueless mesh topology and a backplane * topology lies in whether communication between not directly * connected nodes goes through intermediary nodes (where programs * could run), or through backplane controllers. This affects * placement of programs. * * The type of topology can be discerned with the following tests: * - If the maximum distance between any nodes is 1 hop, the system * is directly connected. * - If for two nodes A and B, located N > 1 hops away from each other, * there is an intermediary node C, which is < N hops away from both * nodes A and B, the system is a glueless mesh. */ static void init_numa_topology_type(void) { int a, b, c, n; n = sched_max_numa_distance; if (sched_domains_numa_levels <= 1) { sched_numa_topology_type = NUMA_DIRECT; return; } for_each_online_node(a) { for_each_online_node(b) { /* Find two nodes furthest removed from each other. */ if (node_distance(a, b) < n) continue; /* Is there an intermediary node between a and b? */ for_each_online_node(c) { if (node_distance(a, c) < n && node_distance(b, c) < n) { sched_numa_topology_type = NUMA_GLUELESS_MESH; return; } } sched_numa_topology_type = NUMA_BACKPLANE; return; } } } void sched_init_numa(void) { int next_distance, curr_distance = node_distance(0, 0); struct sched_domain_topology_level *tl; int level = 0; int i, j, k; sched_domains_numa_distance = kzalloc(sizeof(int) * (nr_node_ids + 1), GFP_KERNEL); if (!sched_domains_numa_distance) return; /* * O(nr_nodes^2) deduplicating selection sort -- in order to find the * unique distances in the node_distance() table. * * Assumes node_distance(0,j) includes all distances in * node_distance(i,j) in order to avoid cubic time. */ next_distance = curr_distance; for (i = 0; i < nr_node_ids; i++) { for (j = 0; j < nr_node_ids; j++) { for (k = 0; k < nr_node_ids; k++) { int distance = node_distance(i, k); if (distance > curr_distance && (distance < next_distance || next_distance == curr_distance)) next_distance = distance; /* * While not a strong assumption it would be nice to know * about cases where if node A is connected to B, B is not * equally connected to A. */ if (sched_debug() && node_distance(k, i) != distance) sched_numa_warn("Node-distance not symmetric"); if (sched_debug() && i && !find_numa_distance(distance)) sched_numa_warn("Node-0 not representative"); } if (next_distance != curr_distance) { sched_domains_numa_distance[level++] = next_distance; sched_domains_numa_levels = level; curr_distance = next_distance; } else break; } /* * In case of sched_debug() we verify the above assumption. */ if (!sched_debug()) break; } if (!level) return; /* * 'level' contains the number of unique distances, excluding the * identity distance node_distance(i,i). * * The sched_domains_numa_distance[] array includes the actual distance * numbers. */ /* * Here, we should temporarily reset sched_domains_numa_levels to 0. * If it fails to allocate memory for array sched_domains_numa_masks[][], * the array will contain less then 'level' members. This could be * dangerous when we use it to iterate array sched_domains_numa_masks[][] * in other functions. * * We reset it to 'level' at the end of this function. */ sched_domains_numa_levels = 0; sched_domains_numa_masks = kzalloc(sizeof(void *) * level, GFP_KERNEL); if (!sched_domains_numa_masks) return; /* * Now for each level, construct a mask per node which contains all * CPUs of nodes that are that many hops away from us. */ for (i = 0; i < level; i++) { sched_domains_numa_masks[i] = kzalloc(nr_node_ids * sizeof(void *), GFP_KERNEL); if (!sched_domains_numa_masks[i]) return; for (j = 0; j < nr_node_ids; j++) { struct cpumask *mask = kzalloc(cpumask_size(), GFP_KERNEL); if (!mask) return; sched_domains_numa_masks[i][j] = mask; for_each_node(k) { if (node_distance(j, k) > sched_domains_numa_distance[i]) continue; cpumask_or(mask, mask, cpumask_of_node(k)); } } } /* Compute default topology size */ for (i = 0; sched_domain_topology[i].mask; i++); tl = kzalloc((i + level + 1) * sizeof(struct sched_domain_topology_level), GFP_KERNEL); if (!tl) return; /* * Copy the default topology bits.. */ for (i = 0; sched_domain_topology[i].mask; i++) tl[i] = sched_domain_topology[i]; /* * .. and append 'j' levels of NUMA goodness. */ for (j = 0; j < level; i++, j++) { tl[i] = (struct sched_domain_topology_level){ .mask = sd_numa_mask, .sd_flags = cpu_numa_flags, .flags = SDTL_OVERLAP, .numa_level = j, SD_INIT_NAME(NUMA) }; } sched_domain_topology = tl; sched_domains_numa_levels = level; sched_max_numa_distance = sched_domains_numa_distance[level - 1]; init_numa_topology_type(); } void sched_domains_numa_masks_set(unsigned int cpu) { int node = cpu_to_node(cpu); int i, j; for (i = 0; i < sched_domains_numa_levels; i++) { for (j = 0; j < nr_node_ids; j++) { if (node_distance(j, node) <= sched_domains_numa_distance[i]) cpumask_set_cpu(cpu, sched_domains_numa_masks[i][j]); } } } void sched_domains_numa_masks_clear(unsigned int cpu) { int i, j; for (i = 0; i < sched_domains_numa_levels; i++) { for (j = 0; j < nr_node_ids; j++) cpumask_clear_cpu(cpu, sched_domains_numa_masks[i][j]); } } #endif /* CONFIG_NUMA */ static int __sdt_alloc(const struct cpumask *cpu_map) { struct sched_domain_topology_level *tl; int j; for_each_sd_topology(tl) { struct sd_data *sdd = &tl->data; sdd->sd = alloc_percpu(struct sched_domain *); if (!sdd->sd) return -ENOMEM; sdd->sds = alloc_percpu(struct sched_domain_shared *); if (!sdd->sds) return -ENOMEM; sdd->sg = alloc_percpu(struct sched_group *); if (!sdd->sg) return -ENOMEM; sdd->sgc = alloc_percpu(struct sched_group_capacity *); if (!sdd->sgc) return -ENOMEM; for_each_cpu(j, cpu_map) { struct sched_domain *sd; struct sched_domain_shared *sds; struct sched_group *sg; struct sched_group_capacity *sgc; sd = kzalloc_node(sizeof(struct sched_domain) + cpumask_size(), GFP_KERNEL, cpu_to_node(j)); if (!sd) return -ENOMEM; *per_cpu_ptr(sdd->sd, j) = sd; sds = kzalloc_node(sizeof(struct sched_domain_shared), GFP_KERNEL, cpu_to_node(j)); if (!sds) return -ENOMEM; *per_cpu_ptr(sdd->sds, j) = sds; sg = kzalloc_node(sizeof(struct sched_group) + cpumask_size(), GFP_KERNEL, cpu_to_node(j)); if (!sg) return -ENOMEM; sg->next = sg; *per_cpu_ptr(sdd->sg, j) = sg; sgc = kzalloc_node(sizeof(struct sched_group_capacity) + cpumask_size(), GFP_KERNEL, cpu_to_node(j)); if (!sgc) return -ENOMEM; #ifdef CONFIG_SCHED_DEBUG sgc->id = j; #endif *per_cpu_ptr(sdd->sgc, j) = sgc; } } return 0; } static void __sdt_free(const struct cpumask *cpu_map) { struct sched_domain_topology_level *tl; int j; for_each_sd_topology(tl) { struct sd_data *sdd = &tl->data; for_each_cpu(j, cpu_map) { struct sched_domain *sd; if (sdd->sd) { sd = *per_cpu_ptr(sdd->sd, j); if (sd && (sd->flags & SD_OVERLAP)) free_sched_groups(sd->groups, 0); kfree(*per_cpu_ptr(sdd->sd, j)); } if (sdd->sds) kfree(*per_cpu_ptr(sdd->sds, j)); if (sdd->sg) kfree(*per_cpu_ptr(sdd->sg, j)); if (sdd->sgc) kfree(*per_cpu_ptr(sdd->sgc, j)); } free_percpu(sdd->sd); sdd->sd = NULL; free_percpu(sdd->sds); sdd->sds = NULL; free_percpu(sdd->sg); sdd->sg = NULL; free_percpu(sdd->sgc); sdd->sgc = NULL; } } static struct sched_domain *build_sched_domain(struct sched_domain_topology_level *tl, const struct cpumask *cpu_map, struct sched_domain_attr *attr, struct sched_domain *child, int cpu) { struct sched_domain *sd = sd_init(tl, cpu_map, child, cpu); if (child) { sd->level = child->level + 1; sched_domain_level_max = max(sched_domain_level_max, sd->level); child->parent = sd; if (!cpumask_subset(sched_domain_span(child), sched_domain_span(sd))) { pr_err("BUG: arch topology borken\n"); #ifdef CONFIG_SCHED_DEBUG pr_err(" the %s domain not a subset of the %s domain\n", child->name, sd->name); #endif /* Fixup, ensure @sd has at least @child cpus. */ cpumask_or(sched_domain_span(sd), sched_domain_span(sd), sched_domain_span(child)); } } set_domain_attribute(sd, attr); return sd; } /* * Build sched domains for a given set of CPUs and attach the sched domains * to the individual CPUs */ static int build_sched_domains(const struct cpumask *cpu_map, struct sched_domain_attr *attr) { enum s_alloc alloc_state; struct sched_domain *sd; struct s_data d; struct rq *rq = NULL; int i, ret = -ENOMEM; alloc_state = __visit_domain_allocation_hell(&d, cpu_map); if (alloc_state != sa_rootdomain) goto error; /* Set up domains for CPUs specified by the cpu_map: */ for_each_cpu(i, cpu_map) { struct sched_domain_topology_level *tl; sd = NULL; for_each_sd_topology(tl) { sd = build_sched_domain(tl, cpu_map, attr, sd, i); if (tl == sched_domain_topology) *per_cpu_ptr(d.sd, i) = sd; if (tl->flags & SDTL_OVERLAP) sd->flags |= SD_OVERLAP; if (cpumask_equal(cpu_map, sched_domain_span(sd))) break; } } /* Build the groups for the domains */ for_each_cpu(i, cpu_map) { for (sd = *per_cpu_ptr(d.sd, i); sd; sd = sd->parent) { sd->span_weight = cpumask_weight(sched_domain_span(sd)); if (sd->flags & SD_OVERLAP) { if (build_overlap_sched_groups(sd, i)) goto error; } else { if (build_sched_groups(sd, i)) goto error; } } } /* Calculate CPU capacity for physical packages and nodes */ for (i = nr_cpumask_bits-1; i >= 0; i--) { if (!cpumask_test_cpu(i, cpu_map)) continue; for (sd = *per_cpu_ptr(d.sd, i); sd; sd = sd->parent) { claim_allocations(i, sd); init_sched_groups_capacity(i, sd); } } /* Attach the domains */ rcu_read_lock(); for_each_cpu(i, cpu_map) { rq = cpu_rq(i); sd = *per_cpu_ptr(d.sd, i); /* Use READ_ONCE()/WRITE_ONCE() to avoid load/store tearing: */ if (rq->cpu_capacity_orig > READ_ONCE(d.rd->max_cpu_capacity)) WRITE_ONCE(d.rd->max_cpu_capacity, rq->cpu_capacity_orig); cpu_attach_domain(sd, d.rd, i); } rcu_read_unlock(); if (rq && sched_debug_enabled) { pr_info("span: %*pbl (max cpu_capacity = %lu)\n", cpumask_pr_args(cpu_map), rq->rd->max_cpu_capacity); } ret = 0; error: __free_domain_allocs(&d, alloc_state, cpu_map); return ret; } /* Current sched domains: */ static cpumask_var_t *doms_cur; /* Number of sched domains in 'doms_cur': */ static int ndoms_cur; /* Attribues of custom domains in 'doms_cur' */ static struct sched_domain_attr *dattr_cur; /* * Special case: If a kmalloc() of a doms_cur partition (array of * cpumask) fails, then fallback to a single sched domain, * as determined by the single cpumask fallback_doms. */ static cpumask_var_t fallback_doms; /* * arch_update_cpu_topology lets virtualized architectures update the * CPU core maps. It is supposed to return 1 if the topology changed * or 0 if it stayed the same. */ int __weak arch_update_cpu_topology(void) { return 0; } cpumask_var_t *alloc_sched_domains(unsigned int ndoms) { int i; cpumask_var_t *doms; doms = kmalloc(sizeof(*doms) * ndoms, GFP_KERNEL); if (!doms) return NULL; for (i = 0; i < ndoms; i++) { if (!alloc_cpumask_var(&doms[i], GFP_KERNEL)) { free_sched_domains(doms, i); return NULL; } } return doms; } void free_sched_domains(cpumask_var_t doms[], unsigned int ndoms) { unsigned int i; for (i = 0; i < ndoms; i++) free_cpumask_var(doms[i]); kfree(doms); } /* * Set up scheduler domains and groups. Callers must hold the hotplug lock. * For now this just excludes isolated CPUs, but could be used to * exclude other special cases in the future. */ int sched_init_domains(const struct cpumask *cpu_map) { int err; zalloc_cpumask_var(&sched_domains_tmpmask, GFP_KERNEL); zalloc_cpumask_var(&sched_domains_tmpmask2, GFP_KERNEL); zalloc_cpumask_var(&fallback_doms, GFP_KERNEL); arch_update_cpu_topology(); ndoms_cur = 1; doms_cur = alloc_sched_domains(ndoms_cur); if (!doms_cur) doms_cur = &fallback_doms; cpumask_andnot(doms_cur[0], cpu_map, cpu_isolated_map); err = build_sched_domains(doms_cur[0], NULL); register_sched_domain_sysctl(); return err; } /* * Detach sched domains from a group of CPUs specified in cpu_map * These CPUs will now be attached to the NULL domain */ static void detach_destroy_domains(const struct cpumask *cpu_map) { int i; rcu_read_lock(); for_each_cpu(i, cpu_map) cpu_attach_domain(NULL, &def_root_domain, i); rcu_read_unlock(); } /* handle null as "default" */ static int dattrs_equal(struct sched_domain_attr *cur, int idx_cur, struct sched_domain_attr *new, int idx_new) { struct sched_domain_attr tmp; /* Fast path: */ if (!new && !cur) return 1; tmp = SD_ATTR_INIT; return !memcmp(cur ? (cur + idx_cur) : &tmp, new ? (new + idx_new) : &tmp, sizeof(struct sched_domain_attr)); } /* * Partition sched domains as specified by the 'ndoms_new' * cpumasks in the array doms_new[] of cpumasks. This compares * doms_new[] to the current sched domain partitioning, doms_cur[]. * It destroys each deleted domain and builds each new domain. * * 'doms_new' is an array of cpumask_var_t's of length 'ndoms_new'. * The masks don't intersect (don't overlap.) We should setup one * sched domain for each mask. CPUs not in any of the cpumasks will * not be load balanced. If the same cpumask appears both in the * current 'doms_cur' domains and in the new 'doms_new', we can leave * it as it is. * * The passed in 'doms_new' should be allocated using * alloc_sched_domains. This routine takes ownership of it and will * free_sched_domains it when done with it. If the caller failed the * alloc call, then it can pass in doms_new == NULL && ndoms_new == 1, * and partition_sched_domains() will fallback to the single partition * 'fallback_doms', it also forces the domains to be rebuilt. * * If doms_new == NULL it will be replaced with cpu_online_mask. * ndoms_new == 0 is a special case for destroying existing domains, * and it will not create the default domain. * * Call with hotplug lock held */ void partition_sched_domains(int ndoms_new, cpumask_var_t doms_new[], struct sched_domain_attr *dattr_new) { int i, j, n; int new_topology; mutex_lock(&sched_domains_mutex); /* Always unregister in case we don't destroy any domains: */ unregister_sched_domain_sysctl(); /* Let the architecture update CPU core mappings: */ new_topology = arch_update_cpu_topology(); if (!doms_new) { WARN_ON_ONCE(dattr_new); n = 0; doms_new = alloc_sched_domains(1); if (doms_new) { n = 1; cpumask_andnot(doms_new[0], cpu_active_mask, cpu_isolated_map); } } else { n = ndoms_new; } /* Destroy deleted domains: */ for (i = 0; i < ndoms_cur; i++) { for (j = 0; j < n && !new_topology; j++) { if (cpumask_equal(doms_cur[i], doms_new[j]) && dattrs_equal(dattr_cur, i, dattr_new, j)) goto match1; } /* No match - a current sched domain not in new doms_new[] */ detach_destroy_domains(doms_cur[i]); match1: ; } n = ndoms_cur; if (!doms_new) { n = 0; doms_new = &fallback_doms; cpumask_andnot(doms_new[0], cpu_active_mask, cpu_isolated_map); } /* Build new domains: */ for (i = 0; i < ndoms_new; i++) { for (j = 0; j < n && !new_topology; j++) { if (cpumask_equal(doms_new[i], doms_cur[j]) && dattrs_equal(dattr_new, i, dattr_cur, j)) goto match2; } /* No match - add a new doms_new */ build_sched_domains(doms_new[i], dattr_new ? dattr_new + i : NULL); match2: ; } /* Remember the new sched domains: */ if (doms_cur != &fallback_doms) free_sched_domains(doms_cur, ndoms_cur); kfree(dattr_cur); doms_cur = doms_new; dattr_cur = dattr_new; ndoms_cur = ndoms_new; register_sched_domain_sysctl(); mutex_unlock(&sched_domains_mutex); }