diff options
Diffstat (limited to '')
| -rw-r--r-- | kernel/sched/topology.c | 2647 |
1 files changed, 2647 insertions, 0 deletions
diff --git a/kernel/sched/topology.c b/kernel/sched/topology.c new file mode 100644 index 000000000..8739c2a5a --- /dev/null +++ b/kernel/sched/topology.c @@ -0,0 +1,2647 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Scheduler topology setup/handling methods + */ + +DEFINE_MUTEX(sched_domains_mutex); + +/* Protected by sched_domains_mutex: */ +static cpumask_var_t sched_domains_tmpmask; +static cpumask_var_t sched_domains_tmpmask2; + +#ifdef CONFIG_SCHED_DEBUG + +static int __init sched_debug_setup(char *str) +{ + sched_debug_verbose = true; + + return 0; +} +early_param("sched_verbose", sched_debug_setup); + +static inline bool sched_debug(void) +{ + return sched_debug_verbose; +} + +#define SD_FLAG(_name, mflags) [__##_name] = { .meta_flags = mflags, .name = #_name }, +const struct sd_flag_debug sd_flag_debug[] = { +#include <linux/sched/sd_flags.h> +}; +#undef SD_FLAG + +static int sched_domain_debug_one(struct sched_domain *sd, int cpu, int level, + struct cpumask *groupmask) +{ + struct sched_group *group = sd->groups; + unsigned long flags = sd->flags; + unsigned int idx; + + cpumask_clear(groupmask); + + printk(KERN_DEBUG "%*s domain-%d: ", level, "", level); + 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 (group && !cpumask_test_cpu(cpu, sched_group_span(group))) { + printk(KERN_ERR "ERROR: domain->groups does not contain CPU%d\n", cpu); + } + + for_each_set_bit(idx, &flags, __SD_FLAG_CNT) { + unsigned int flag = BIT(idx); + unsigned int meta_flags = sd_flag_debug[idx].meta_flags; + + if ((meta_flags & SDF_SHARED_CHILD) && sd->child && + !(sd->child->flags & flag)) + printk(KERN_ERR "ERROR: flag %s set here but not in child\n", + sd_flag_debug[idx].name); + + if ((meta_flags & SDF_SHARED_PARENT) && sd->parent && + !(sd->parent->flags & flag)) + printk(KERN_ERR "ERROR: flag %s set here but not in parent\n", + sd_flag_debug[idx].name); + } + + printk(KERN_DEBUG "%*s groups:", level + 1, ""); + do { + if (!group) { + printk("\n"); + printk(KERN_ERR "ERROR: group is NULL\n"); + break; + } + + if (cpumask_empty(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_verbose) + 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_verbose 0 +# define sched_domain_debug(sd, cpu) do { } while (0) +static inline bool sched_debug(void) +{ + return false; +} +#endif /* CONFIG_SCHED_DEBUG */ + +/* Generate a mask of SD flags with the SDF_NEEDS_GROUPS metaflag */ +#define SD_FLAG(name, mflags) (name * !!((mflags) & SDF_NEEDS_GROUPS)) | +static const unsigned int SD_DEGENERATE_GROUPS_MASK = +#include <linux/sched/sd_flags.h> +0; +#undef SD_FLAG + +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_DEGENERATE_GROUPS_MASK) && + (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_DEGENERATE_GROUPS_MASK; + + if (~cflags & pflags) + return 0; + + return 1; +} + +#if defined(CONFIG_ENERGY_MODEL) && defined(CONFIG_CPU_FREQ_GOV_SCHEDUTIL) +DEFINE_STATIC_KEY_FALSE(sched_energy_present); +static unsigned int sysctl_sched_energy_aware = 1; +DEFINE_MUTEX(sched_energy_mutex); +bool sched_energy_update; + +void rebuild_sched_domains_energy(void) +{ + mutex_lock(&sched_energy_mutex); + sched_energy_update = true; + rebuild_sched_domains(); + sched_energy_update = false; + mutex_unlock(&sched_energy_mutex); +} + +#ifdef CONFIG_PROC_SYSCTL +static int sched_energy_aware_handler(struct ctl_table *table, int write, + void *buffer, size_t *lenp, loff_t *ppos) +{ + int ret, state; + + if (write && !capable(CAP_SYS_ADMIN)) + return -EPERM; + + ret = proc_dointvec_minmax(table, write, buffer, lenp, ppos); + if (!ret && write) { + state = static_branch_unlikely(&sched_energy_present); + if (state != sysctl_sched_energy_aware) + rebuild_sched_domains_energy(); + } + + return ret; +} + +static struct ctl_table sched_energy_aware_sysctls[] = { + { + .procname = "sched_energy_aware", + .data = &sysctl_sched_energy_aware, + .maxlen = sizeof(unsigned int), + .mode = 0644, + .proc_handler = sched_energy_aware_handler, + .extra1 = SYSCTL_ZERO, + .extra2 = SYSCTL_ONE, + }, + {} +}; + +static int __init sched_energy_aware_sysctl_init(void) +{ + register_sysctl_init("kernel", sched_energy_aware_sysctls); + return 0; +} + +late_initcall(sched_energy_aware_sysctl_init); +#endif + +static void free_pd(struct perf_domain *pd) +{ + struct perf_domain *tmp; + + while (pd) { + tmp = pd->next; + kfree(pd); + pd = tmp; + } +} + +static struct perf_domain *find_pd(struct perf_domain *pd, int cpu) +{ + while (pd) { + if (cpumask_test_cpu(cpu, perf_domain_span(pd))) + return pd; + pd = pd->next; + } + + return NULL; +} + +static struct perf_domain *pd_init(int cpu) +{ + struct em_perf_domain *obj = em_cpu_get(cpu); + struct perf_domain *pd; + + if (!obj) { + if (sched_debug()) + pr_info("%s: no EM found for CPU%d\n", __func__, cpu); + return NULL; + } + + pd = kzalloc(sizeof(*pd), GFP_KERNEL); + if (!pd) + return NULL; + pd->em_pd = obj; + + return pd; +} + +static void perf_domain_debug(const struct cpumask *cpu_map, + struct perf_domain *pd) +{ + if (!sched_debug() || !pd) + return; + + printk(KERN_DEBUG "root_domain %*pbl:", cpumask_pr_args(cpu_map)); + + while (pd) { + printk(KERN_CONT " pd%d:{ cpus=%*pbl nr_pstate=%d }", + cpumask_first(perf_domain_span(pd)), + cpumask_pr_args(perf_domain_span(pd)), + em_pd_nr_perf_states(pd->em_pd)); + pd = pd->next; + } + + printk(KERN_CONT "\n"); +} + +static void destroy_perf_domain_rcu(struct rcu_head *rp) +{ + struct perf_domain *pd; + + pd = container_of(rp, struct perf_domain, rcu); + free_pd(pd); +} + +static void sched_energy_set(bool has_eas) +{ + if (!has_eas && static_branch_unlikely(&sched_energy_present)) { + if (sched_debug()) + pr_info("%s: stopping EAS\n", __func__); + static_branch_disable_cpuslocked(&sched_energy_present); + } else if (has_eas && !static_branch_unlikely(&sched_energy_present)) { + if (sched_debug()) + pr_info("%s: starting EAS\n", __func__); + static_branch_enable_cpuslocked(&sched_energy_present); + } +} + +/* + * EAS can be used on a root domain if it meets all the following conditions: + * 1. an Energy Model (EM) is available; + * 2. the SD_ASYM_CPUCAPACITY flag is set in the sched_domain hierarchy. + * 3. no SMT is detected. + * 4. the EM complexity is low enough to keep scheduling overheads low; + * 5. schedutil is driving the frequency of all CPUs of the rd; + * 6. frequency invariance support is present; + * + * The complexity of the Energy Model is defined as: + * + * C = nr_pd * (nr_cpus + nr_ps) + * + * with parameters defined as: + * - nr_pd: the number of performance domains + * - nr_cpus: the number of CPUs + * - nr_ps: the sum of the number of performance states of all performance + * domains (for example, on a system with 2 performance domains, + * with 10 performance states each, nr_ps = 2 * 10 = 20). + * + * It is generally not a good idea to use such a model in the wake-up path on + * very complex platforms because of the associated scheduling overheads. The + * arbitrary constraint below prevents that. It makes EAS usable up to 16 CPUs + * with per-CPU DVFS and less than 8 performance states each, for example. + */ +#define EM_MAX_COMPLEXITY 2048 + +extern struct cpufreq_governor schedutil_gov; +static bool build_perf_domains(const struct cpumask *cpu_map) +{ + int i, nr_pd = 0, nr_ps = 0, nr_cpus = cpumask_weight(cpu_map); + struct perf_domain *pd = NULL, *tmp; + int cpu = cpumask_first(cpu_map); + struct root_domain *rd = cpu_rq(cpu)->rd; + struct cpufreq_policy *policy; + struct cpufreq_governor *gov; + + if (!sysctl_sched_energy_aware) + goto free; + + /* EAS is enabled for asymmetric CPU capacity topologies. */ + if (!per_cpu(sd_asym_cpucapacity, cpu)) { + if (sched_debug()) { + pr_info("rd %*pbl: CPUs do not have asymmetric capacities\n", + cpumask_pr_args(cpu_map)); + } + goto free; + } + + /* EAS definitely does *not* handle SMT */ + if (sched_smt_active()) { + pr_warn("rd %*pbl: Disabling EAS, SMT is not supported\n", + cpumask_pr_args(cpu_map)); + goto free; + } + + if (!arch_scale_freq_invariant()) { + if (sched_debug()) { + pr_warn("rd %*pbl: Disabling EAS: frequency-invariant load tracking not yet supported", + cpumask_pr_args(cpu_map)); + } + goto free; + } + + for_each_cpu(i, cpu_map) { + /* Skip already covered CPUs. */ + if (find_pd(pd, i)) + continue; + + /* Do not attempt EAS if schedutil is not being used. */ + policy = cpufreq_cpu_get(i); + if (!policy) + goto free; + gov = policy->governor; + cpufreq_cpu_put(policy); + if (gov != &schedutil_gov) { + if (rd->pd) + pr_warn("rd %*pbl: Disabling EAS, schedutil is mandatory\n", + cpumask_pr_args(cpu_map)); + goto free; + } + + /* Create the new pd and add it to the local list. */ + tmp = pd_init(i); + if (!tmp) + goto free; + tmp->next = pd; + pd = tmp; + + /* + * Count performance domains and performance states for the + * complexity check. + */ + nr_pd++; + nr_ps += em_pd_nr_perf_states(pd->em_pd); + } + + /* Bail out if the Energy Model complexity is too high. */ + if (nr_pd * (nr_ps + nr_cpus) > EM_MAX_COMPLEXITY) { + WARN(1, "rd %*pbl: Failed to start EAS, EM complexity is too high\n", + cpumask_pr_args(cpu_map)); + goto free; + } + + perf_domain_debug(cpu_map, pd); + + /* Attach the new list of performance domains to the root domain. */ + tmp = rd->pd; + rcu_assign_pointer(rd->pd, pd); + if (tmp) + call_rcu(&tmp->rcu, destroy_perf_domain_rcu); + + return !!pd; + +free: + free_pd(pd); + tmp = rd->pd; + rcu_assign_pointer(rd->pd, NULL); + if (tmp) + call_rcu(&tmp->rcu, destroy_perf_domain_rcu); + + return false; +} +#else +static void free_pd(struct perf_domain *pd) { } +#endif /* CONFIG_ENERGY_MODEL && CONFIG_CPU_FREQ_GOV_SCHEDUTIL*/ + +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); + free_pd(rd->pd); + kfree(rd); +} + +void rq_attach_root(struct rq *rq, struct root_domain *rd) +{ + struct root_domain *old_rd = NULL; + unsigned long flags; + + raw_spin_rq_lock_irqsave(rq, 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_rq_unlock_irqrestore(rq, flags); + + if (old_rd) + call_rcu(&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(&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); + rd->rto_push_work = IRQ_WORK_INIT_HARD(rto_push_irq_work_func); +#endif + + rd->visit_gen = 0; + 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 __rcu *, sd_llc); +DEFINE_PER_CPU(int, sd_llc_size); +DEFINE_PER_CPU(int, sd_llc_id); +DEFINE_PER_CPU(struct sched_domain_shared __rcu *, sd_llc_shared); +DEFINE_PER_CPU(struct sched_domain __rcu *, sd_numa); +DEFINE_PER_CPU(struct sched_domain __rcu *, sd_asym_packing); +DEFINE_PER_CPU(struct sched_domain __rcu *, sd_asym_cpucapacity); +DEFINE_STATIC_KEY_FALSE(sched_asym_cpucapacity); + +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_packing, cpu), sd); + + sd = lowest_flag_domain(cpu, SD_ASYM_CPUCAPACITY_FULL); + rcu_assign_pointer(per_cpu(sd_asym_cpucapacity, 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) { + struct sched_group *sg = sd->groups; + + /* + * sched groups hold the flags of the child sched + * domain for convenience. Clear such flags since + * the child is being destroyed. + */ + do { + sg->flags = 0; + } while (sg != sd->groups); + + 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); +} + +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)); + sg->flags = sd->child->flags; + } 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(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; + sg->sgc->max_capacity = SCHED_CAPACITY_SCALE; +} + +static struct sched_domain * +find_descended_sibling(struct sched_domain *sd, struct sched_domain *sibling) +{ + /* + * The proper descendant would be the one whose child won't span out + * of sd + */ + while (sibling->child && + !cpumask_subset(sched_domain_span(sibling->child), + sched_domain_span(sd))) + sibling = sibling->child; + + /* + * As we are referencing sgc across different topology level, we need + * to go down to skip those sched_domains which don't contribute to + * scheduling because they will be degenerated in cpu_attach_domain + */ + while (sibling->child && + cpumask_equal(sched_domain_span(sibling->child), + sched_domain_span(sibling))) + sibling = sibling->child; + + return sibling; +} + +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; + + /* + * Usually we build sched_group by sibling's child sched_domain + * But for machines whose NUMA diameter are 3 or above, we move + * to build sched_group by sibling's proper descendant's child + * domain because sibling's child sched_domain will span out of + * the sched_domain being built as below. + * + * Smallest diameter=3 topology is: + * + * node 0 1 2 3 + * 0: 10 20 30 40 + * 1: 20 10 20 30 + * 2: 30 20 10 20 + * 3: 40 30 20 10 + * + * 0 --- 1 --- 2 --- 3 + * + * NUMA-3 0-3 N/A N/A 0-3 + * groups: {0-2},{1-3} {1-3},{0-2} + * + * NUMA-2 0-2 0-3 0-3 1-3 + * groups: {0-1},{1-3} {0-2},{2-3} {1-3},{0-1} {2-3},{0-2} + * + * NUMA-1 0-1 0-2 1-3 2-3 + * groups: {0},{1} {1},{2},{0} {2},{3},{1} {3},{2} + * + * NUMA-0 0 1 2 3 + * + * The NUMA-2 groups for nodes 0 and 3 are obviously buggered, as the + * group span isn't a subset of the domain span. + */ + if (sibling->child && + !cpumask_subset(sched_domain_span(sibling->child), span)) + sibling = find_descended_sibling(sd, sibling); + + 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(sibling, 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; + bool already_visited; + + if (child) + cpu = cpumask_first(sched_domain_span(child)); + + sg = *per_cpu_ptr(sdd->sg, cpu); + sg->sgc = *per_cpu_ptr(sdd->sgc, cpu); + + /* Increase refcounts for claim_allocations: */ + already_visited = atomic_inc_return(&sg->ref) > 1; + /* sgc visits should follow a similar trend as sg */ + WARN_ON(already_visited != (atomic_inc_return(&sg->sgc->ref) > 1)); + + /* If we have already visited that group, it's already initialized. */ + if (already_visited) + return sg; + + if (child) { + cpumask_copy(sched_group_span(sg), sched_domain_span(child)); + cpumask_copy(group_balance_mask(sg), sched_group_span(sg)); + sg->flags = child->flags; + } 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; + sg->sgc->max_capacity = SCHED_CAPACITY_SCALE; + + return sg; +} + +/* + * build_sched_groups will build a circular linked list of the groups + * covered by the given span, will set each group's ->cpumask correctly, + * and will initialize their ->sgc. + * + * 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); +} + +/* + * Asymmetric CPU capacity bits + */ +struct asym_cap_data { + struct list_head link; + unsigned long capacity; + unsigned long cpus[]; +}; + +/* + * Set of available CPUs grouped by their corresponding capacities + * Each list entry contains a CPU mask reflecting CPUs that share the same + * capacity. + * The lifespan of data is unlimited. + */ +static LIST_HEAD(asym_cap_list); + +#define cpu_capacity_span(asym_data) to_cpumask((asym_data)->cpus) + +/* + * Verify whether there is any CPU capacity asymmetry in a given sched domain. + * Provides sd_flags reflecting the asymmetry scope. + */ +static inline int +asym_cpu_capacity_classify(const struct cpumask *sd_span, + const struct cpumask *cpu_map) +{ + struct asym_cap_data *entry; + int count = 0, miss = 0; + + /* + * Count how many unique CPU capacities this domain spans across + * (compare sched_domain CPUs mask with ones representing available + * CPUs capacities). Take into account CPUs that might be offline: + * skip those. + */ + list_for_each_entry(entry, &asym_cap_list, link) { + if (cpumask_intersects(sd_span, cpu_capacity_span(entry))) + ++count; + else if (cpumask_intersects(cpu_map, cpu_capacity_span(entry))) + ++miss; + } + + WARN_ON_ONCE(!count && !list_empty(&asym_cap_list)); + + /* No asymmetry detected */ + if (count < 2) + return 0; + /* Some of the available CPU capacity values have not been detected */ + if (miss) + return SD_ASYM_CPUCAPACITY; + + /* Full asymmetry */ + return SD_ASYM_CPUCAPACITY | SD_ASYM_CPUCAPACITY_FULL; + +} + +static inline void asym_cpu_capacity_update_data(int cpu) +{ + unsigned long capacity = arch_scale_cpu_capacity(cpu); + struct asym_cap_data *entry = NULL; + + list_for_each_entry(entry, &asym_cap_list, link) { + if (capacity == entry->capacity) + goto done; + } + + entry = kzalloc(sizeof(*entry) + cpumask_size(), GFP_KERNEL); + if (WARN_ONCE(!entry, "Failed to allocate memory for asymmetry data\n")) + return; + entry->capacity = capacity; + list_add(&entry->link, &asym_cap_list); +done: + __cpumask_set_cpu(cpu, cpu_capacity_span(entry)); +} + +/* + * Build-up/update list of CPUs grouped by their capacities + * An update requires explicit request to rebuild sched domains + * with state indicating CPU topology changes. + */ +static void asym_cpu_capacity_scan(void) +{ + struct asym_cap_data *entry, *next; + int cpu; + + list_for_each_entry(entry, &asym_cap_list, link) + cpumask_clear(cpu_capacity_span(entry)); + + for_each_cpu_and(cpu, cpu_possible_mask, housekeeping_cpumask(HK_TYPE_DOMAIN)) + asym_cpu_capacity_update_data(cpu); + + list_for_each_entry_safe(entry, next, &asym_cap_list, link) { + if (cpumask_empty(cpu_capacity_span(entry))) { + list_del(&entry->link); + kfree(entry); + } + } + + /* + * Only one capacity value has been detected i.e. this system is symmetric. + * No need to keep this data around. + */ + if (list_is_singular(&asym_cap_list)) { + entry = list_first_entry(&asym_cap_list, typeof(*entry), link); + list_del(&entry->link); + kfree(entry); + } +} + +/* + * 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; + request = default_relax_domain_level; + } else + request = attr->relax_domain_level; + + if (sd->level > request) { + /* Turn off 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); + fallthrough; + case sa_sd: + free_percpu(d->sd); + fallthrough; + case sa_sd_storage: + __sdt_free(cpu_map); + fallthrough; + 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 +enum numa_topology_type sched_numa_topology_type; + +static int sched_domains_numa_levels; +static int sched_domains_curr_level; + +int sched_max_numa_distance; +static int *sched_domains_numa_distance; +static struct cpumask ***sched_domains_numa_masks; +#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 + * + * 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) + +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; + struct cpumask *sd_span; + +#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 = 16, + .imbalance_pct = 117, + + .cache_nice_tries = 0, + + .flags = 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 + | 1*SD_PREFER_SIBLING + | 0*SD_NUMA + | sd_flags + , + + .last_balance = jiffies, + .balance_interval = sd_weight, + .max_newidle_lb_cost = 0, + .last_decay_max_lb_cost = jiffies, + .child = child, +#ifdef CONFIG_SCHED_DEBUG + .name = tl->name, +#endif + }; + + sd_span = sched_domain_span(sd); + cpumask_and(sd_span, cpu_map, tl->mask(cpu)); + sd_id = cpumask_first(sd_span); + + sd->flags |= asym_cpu_capacity_classify(sd_span, cpu_map); + + WARN_ONCE((sd->flags & (SD_SHARE_CPUCAPACITY | SD_ASYM_CPUCAPACITY)) == + (SD_SHARE_CPUCAPACITY | SD_ASYM_CPUCAPACITY), + "CPU capacity asymmetry not supported on SMT\n"); + + /* + * Convert topological properties into behaviour. + */ + /* Don't attempt to spread across CPUs of different capacities. */ + if ((sd->flags & SD_ASYM_CPUCAPACITY) && sd->child) + sd->child->flags &= ~SD_PREFER_SIBLING; + + if (sd->flags & SD_SHARE_CPUCAPACITY) { + sd->imbalance_pct = 110; + + } else if (sd->flags & SD_SHARE_PKG_RESOURCES) { + sd->imbalance_pct = 117; + sd->cache_nice_tries = 1; + +#ifdef CONFIG_NUMA + } else if (sd->flags & SD_NUMA) { + sd->cache_nice_tries = 2; + + sd->flags &= ~SD_PREFER_SIBLING; + sd->flags |= SD_SERIALIZE; + if (sched_domains_numa_distance[tl->numa_level] > node_reclaim_distance) { + sd->flags &= ~(SD_BALANCE_EXEC | + SD_BALANCE_FORK | + SD_WAKE_AFFINE); + } + +#endif + } else { + sd->cache_nice_tries = 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_CLUSTER + { cpu_clustergroup_mask, cpu_cluster_flags, SD_INIT_NAME(CLS) }, +#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; +static struct sched_domain_topology_level *sched_domain_topology_saved; + +#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; + sched_domain_topology_saved = NULL; +} + +#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++) { + if (!node_state(i, N_CPU) || !node_state(j, N_CPU)) + printk(KERN_CONT "(%02d) ", node_distance(i,j)); + else + printk(KERN_CONT " %02d ", node_distance(i,j)); + } + printk(KERN_CONT "\n"); + } + printk(KERN_WARNING "\n"); +} + +bool find_numa_distance(int distance) +{ + bool found = false; + int i, *distances; + + if (distance == node_distance(0, 0)) + return true; + + rcu_read_lock(); + distances = rcu_dereference(sched_domains_numa_distance); + if (!distances) + goto unlock; + for (i = 0; i < sched_domains_numa_levels; i++) { + if (distances[i] == distance) { + found = true; + break; + } + } +unlock: + rcu_read_unlock(); + + return found; +} + +#define for_each_cpu_node_but(n, nbut) \ + for_each_node_state(n, N_CPU) \ + if (n == nbut) \ + continue; \ + else + +/* + * 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(int offline_node) +{ + int a, b, c, n; + + n = sched_max_numa_distance; + + if (sched_domains_numa_levels <= 2) { + sched_numa_topology_type = NUMA_DIRECT; + return; + } + + for_each_cpu_node_but(a, offline_node) { + for_each_cpu_node_but(b, offline_node) { + /* 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_cpu_node_but(c, offline_node) { + 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; + } + } + + pr_err("Failed to find a NUMA topology type, defaulting to DIRECT\n"); + sched_numa_topology_type = NUMA_DIRECT; +} + + +#define NR_DISTANCE_VALUES (1 << DISTANCE_BITS) + +void sched_init_numa(int offline_node) +{ + struct sched_domain_topology_level *tl; + unsigned long *distance_map; + int nr_levels = 0; + int i, j; + int *distances; + struct cpumask ***masks; + + /* + * O(nr_nodes^2) deduplicating selection sort -- in order to find the + * unique distances in the node_distance() table. + */ + distance_map = bitmap_alloc(NR_DISTANCE_VALUES, GFP_KERNEL); + if (!distance_map) + return; + + bitmap_zero(distance_map, NR_DISTANCE_VALUES); + for_each_cpu_node_but(i, offline_node) { + for_each_cpu_node_but(j, offline_node) { + int distance = node_distance(i, j); + + if (distance < LOCAL_DISTANCE || distance >= NR_DISTANCE_VALUES) { + sched_numa_warn("Invalid distance value range"); + bitmap_free(distance_map); + return; + } + + bitmap_set(distance_map, distance, 1); + } + } + /* + * We can now figure out how many unique distance values there are and + * allocate memory accordingly. + */ + nr_levels = bitmap_weight(distance_map, NR_DISTANCE_VALUES); + + distances = kcalloc(nr_levels, sizeof(int), GFP_KERNEL); + if (!distances) { + bitmap_free(distance_map); + return; + } + + for (i = 0, j = 0; i < nr_levels; i++, j++) { + j = find_next_bit(distance_map, NR_DISTANCE_VALUES, j); + distances[i] = j; + } + rcu_assign_pointer(sched_domains_numa_distance, distances); + + bitmap_free(distance_map); + + /* + * 'nr_levels' contains the number of unique distances + * + * 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 'nr_levels' members. This could be + * dangerous when we use it to iterate array sched_domains_numa_masks[][] + * in other functions. + * + * We reset it to 'nr_levels' at the end of this function. + */ + sched_domains_numa_levels = 0; + + masks = kzalloc(sizeof(void *) * nr_levels, GFP_KERNEL); + if (!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 < nr_levels; i++) { + masks[i] = kzalloc(nr_node_ids * sizeof(void *), GFP_KERNEL); + if (!masks[i]) + return; + + for_each_cpu_node_but(j, offline_node) { + struct cpumask *mask = kzalloc(cpumask_size(), GFP_KERNEL); + int k; + + if (!mask) + return; + + masks[i][j] = mask; + + for_each_cpu_node_but(k, offline_node) { + if (sched_debug() && (node_distance(j, k) != node_distance(k, j))) + sched_numa_warn("Node-distance not symmetric"); + + if (node_distance(j, k) > sched_domains_numa_distance[i]) + continue; + + cpumask_or(mask, mask, cpumask_of_node(k)); + } + } + } + rcu_assign_pointer(sched_domains_numa_masks, masks); + + /* Compute default topology size */ + for (i = 0; sched_domain_topology[i].mask; i++); + + tl = kzalloc((i + nr_levels + 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]; + + /* + * Add the NUMA identity distance, aka single NODE. + */ + tl[i++] = (struct sched_domain_topology_level){ + .mask = sd_numa_mask, + .numa_level = 0, + SD_INIT_NAME(NODE) + }; + + /* + * .. and append 'j' levels of NUMA goodness. + */ + for (j = 1; j < nr_levels; 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_saved = sched_domain_topology; + sched_domain_topology = tl; + + sched_domains_numa_levels = nr_levels; + WRITE_ONCE(sched_max_numa_distance, sched_domains_numa_distance[nr_levels - 1]); + + init_numa_topology_type(offline_node); +} + + +static void sched_reset_numa(void) +{ + int nr_levels, *distances; + struct cpumask ***masks; + + nr_levels = sched_domains_numa_levels; + sched_domains_numa_levels = 0; + sched_max_numa_distance = 0; + sched_numa_topology_type = NUMA_DIRECT; + distances = sched_domains_numa_distance; + rcu_assign_pointer(sched_domains_numa_distance, NULL); + masks = sched_domains_numa_masks; + rcu_assign_pointer(sched_domains_numa_masks, NULL); + if (distances || masks) { + int i, j; + + synchronize_rcu(); + kfree(distances); + for (i = 0; i < nr_levels && masks; i++) { + if (!masks[i]) + continue; + for_each_node(j) + kfree(masks[i][j]); + kfree(masks[i]); + } + kfree(masks); + } + if (sched_domain_topology_saved) { + kfree(sched_domain_topology); + sched_domain_topology = sched_domain_topology_saved; + sched_domain_topology_saved = NULL; + } +} + +/* + * Call with hotplug lock held + */ +void sched_update_numa(int cpu, bool online) +{ + int node; + + node = cpu_to_node(cpu); + /* + * Scheduler NUMA topology is updated when the first CPU of a + * node is onlined or the last CPU of a node is offlined. + */ + if (cpumask_weight(cpumask_of_node(node)) != 1) + return; + + sched_reset_numa(); + sched_init_numa(online ? NUMA_NO_NODE : node); +} + +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_state(j, N_CPU)) + continue; + + /* Set ourselves in the remote node's masks */ + 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++) { + if (sched_domains_numa_masks[i][j]) + cpumask_clear_cpu(cpu, sched_domains_numa_masks[i][j]); + } + } +} + +/* + * sched_numa_find_closest() - given the NUMA topology, find the cpu + * closest to @cpu from @cpumask. + * cpumask: cpumask to find a cpu from + * cpu: cpu to be close to + * + * returns: cpu, or nr_cpu_ids when nothing found. + */ +int sched_numa_find_closest(const struct cpumask *cpus, int cpu) +{ + int i, j = cpu_to_node(cpu), found = nr_cpu_ids; + struct cpumask ***masks; + + rcu_read_lock(); + masks = rcu_dereference(sched_domains_numa_masks); + if (!masks) + goto unlock; + for (i = 0; i < sched_domains_numa_levels; i++) { + if (!masks[i][j]) + break; + cpu = cpumask_any_and(cpus, masks[i][j]); + if (cpu < nr_cpu_ids) { + found = cpu; + break; + } + } +unlock: + rcu_read_unlock(); + + return found; +} + +#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; +} + +/* + * Ensure topology masks are sane, i.e. there are no conflicts (overlaps) for + * any two given CPUs at this (non-NUMA) topology level. + */ +static bool topology_span_sane(struct sched_domain_topology_level *tl, + const struct cpumask *cpu_map, int cpu) +{ + int i; + + /* NUMA levels are allowed to overlap */ + if (tl->flags & SDTL_OVERLAP) + return true; + + /* + * Non-NUMA levels cannot partially overlap - they must be either + * completely equal or completely disjoint. Otherwise we can end up + * breaking the sched_group lists - i.e. a later get_group() pass + * breaks the linking done for an earlier span. + */ + for_each_cpu(i, cpu_map) { + if (i == cpu) + continue; + /* + * We should 'and' all those masks with 'cpu_map' to exactly + * match the topology we're about to build, but that can only + * remove CPUs, which only lessens our ability to detect + * overlaps + */ + if (!cpumask_equal(tl->mask(cpu), tl->mask(i)) && + cpumask_intersects(tl->mask(cpu), tl->mask(i))) + return false; + } + + return true; +} + +/* + * 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 = sa_none; + struct sched_domain *sd; + struct s_data d; + struct rq *rq = NULL; + int i, ret = -ENOMEM; + bool has_asym = false; + + if (WARN_ON(cpumask_empty(cpu_map))) + goto error; + + 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) { + + if (WARN_ON(!topology_span_sane(tl, cpu_map, i))) + goto error; + + sd = build_sched_domain(tl, cpu_map, attr, sd, i); + + has_asym |= sd->flags & SD_ASYM_CPUCAPACITY; + + 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 an allowed NUMA imbalance such that LLCs do not get + * imbalanced. + */ + for_each_cpu(i, cpu_map) { + unsigned int imb = 0; + unsigned int imb_span = 1; + + for (sd = *per_cpu_ptr(d.sd, i); sd; sd = sd->parent) { + struct sched_domain *child = sd->child; + + if (!(sd->flags & SD_SHARE_PKG_RESOURCES) && child && + (child->flags & SD_SHARE_PKG_RESOURCES)) { + struct sched_domain __rcu *top_p; + unsigned int nr_llcs; + + /* + * For a single LLC per node, allow an + * imbalance up to 12.5% of the node. This is + * arbitrary cutoff based two factors -- SMT and + * memory channels. For SMT-2, the intent is to + * avoid premature sharing of HT resources but + * SMT-4 or SMT-8 *may* benefit from a different + * cutoff. For memory channels, this is a very + * rough estimate of how many channels may be + * active and is based on recent CPUs with + * many cores. + * + * For multiple LLCs, allow an imbalance + * until multiple tasks would share an LLC + * on one node while LLCs on another node + * remain idle. This assumes that there are + * enough logical CPUs per LLC to avoid SMT + * factors and that there is a correlation + * between LLCs and memory channels. + */ + nr_llcs = sd->span_weight / child->span_weight; + if (nr_llcs == 1) + imb = sd->span_weight >> 3; + else + imb = nr_llcs; + imb = max(1U, imb); + sd->imb_numa_nr = imb; + + /* Set span based on the first NUMA domain. */ + top_p = sd->parent; + while (top_p && !(top_p->flags & SD_NUMA)) { + top_p = top_p->parent; + } + imb_span = top_p ? top_p->span_weight : sd->span_weight; + } else { + int factor = max(1U, (sd->span_weight / imb_span)); + + sd->imb_numa_nr = imb * factor; + } + } + } + + /* 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 (has_asym) + static_branch_inc_cpuslocked(&sched_asym_cpucapacity); + + if (rq && sched_debug_verbose) { + pr_info("root domain 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; + +/* Attributes 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_array(ndoms, sizeof(*doms), 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. 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(); + asym_cpu_capacity_scan(); + ndoms_cur = 1; + doms_cur = alloc_sched_domains(ndoms_cur); + if (!doms_cur) + doms_cur = &fallback_doms; + cpumask_and(doms_cur[0], cpu_map, housekeeping_cpumask(HK_TYPE_DOMAIN)); + err = build_sched_domains(doms_cur[0], NULL); + + 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) +{ + unsigned int cpu = cpumask_any(cpu_map); + int i; + + if (rcu_access_pointer(per_cpu(sd_asym_cpucapacity, cpu))) + static_branch_dec_cpuslocked(&sched_asym_cpucapacity); + + 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 and sched_domains_mutex held + */ +void partition_sched_domains_locked(int ndoms_new, cpumask_var_t doms_new[], + struct sched_domain_attr *dattr_new) +{ + bool __maybe_unused has_eas = false; + int i, j, n; + int new_topology; + + lockdep_assert_held(&sched_domains_mutex); + + /* Let the architecture update CPU core mappings: */ + new_topology = arch_update_cpu_topology(); + /* Trigger rebuilding CPU capacity asymmetry data */ + if (new_topology) + asym_cpu_capacity_scan(); + + if (!doms_new) { + WARN_ON_ONCE(dattr_new); + n = 0; + doms_new = alloc_sched_domains(1); + if (doms_new) { + n = 1; + cpumask_and(doms_new[0], cpu_active_mask, + housekeeping_cpumask(HK_TYPE_DOMAIN)); + } + } 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)) { + struct root_domain *rd; + + /* + * This domain won't be destroyed and as such + * its dl_bw->total_bw needs to be cleared. It + * will be recomputed in function + * update_tasks_root_domain(). + */ + rd = cpu_rq(cpumask_any(doms_cur[i]))->rd; + dl_clear_root_domain(rd); + 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_and(doms_new[0], cpu_active_mask, + housekeeping_cpumask(HK_TYPE_DOMAIN)); + } + + /* 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: + ; + } + +#if defined(CONFIG_ENERGY_MODEL) && defined(CONFIG_CPU_FREQ_GOV_SCHEDUTIL) + /* Build perf. domains: */ + for (i = 0; i < ndoms_new; i++) { + for (j = 0; j < n && !sched_energy_update; j++) { + if (cpumask_equal(doms_new[i], doms_cur[j]) && + cpu_rq(cpumask_first(doms_cur[j]))->rd->pd) { + has_eas = true; + goto match3; + } + } + /* No match - add perf. domains for a new rd */ + has_eas |= build_perf_domains(doms_new[i]); +match3: + ; + } + sched_energy_set(has_eas); +#endif + + /* 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; + + update_sched_domain_debugfs(); +} + +/* + * Call with hotplug lock held + */ +void partition_sched_domains(int ndoms_new, cpumask_var_t doms_new[], + struct sched_domain_attr *dattr_new) +{ + mutex_lock(&sched_domains_mutex); + partition_sched_domains_locked(ndoms_new, doms_new, dattr_new); + mutex_unlock(&sched_domains_mutex); +} |