sched: Allow for overlapping sched_domain spans
Allow for sched_domain spans that overlap by giving such domains their own sched_group list instead of sharing the sched_groups amongst each-other. This is needed for machines with more than 16 nodes, because sched_domain_node_span() will generate a node mask from the 16 nearest nodes without regard if these masks have any overlap. Currently sched_domains have a sched_group that maps to their child sched_domain span, and since there is no overlap we share the sched_group between the sched_domains of the various CPUs. If however there is overlap, we would need to link the sched_group list in different ways for each cpu, and hence sharing isn't possible. In order to solve this, allocate private sched_groups for each CPU's sched_domain but have the sched_groups share a sched_group_power structure such that we can uniquely track the power. Reported-and-tested-by: Anton Blanchard <anton@samba.org> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Andrew Morton <akpm@linux-foundation.org> Link: http://lkml.kernel.org/n/tip-08bxqw9wis3qti9u5inifh3y@git.kernel.org Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Peter Zijlstra
Ingo Molnar
Родитель
9c3f75cbd1
Коммит
e3589f6c81
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@ -844,6 +844,7 @@ enum cpu_idle_type {
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#define SD_SERIALIZE 0x0400 /* Only a single load balancing instance */
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#define SD_ASYM_PACKING 0x0800 /* Place busy groups earlier in the domain */
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#define SD_PREFER_SIBLING 0x1000 /* Prefer to place tasks in a sibling domain */
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#define SD_OVERLAP 0x2000 /* sched_domains of this level overlap */
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enum powersavings_balance_level {
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POWERSAVINGS_BALANCE_NONE = 0, /* No power saving load balance */
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@ -894,6 +895,7 @@ static inline int sd_power_saving_flags(void)
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}
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struct sched_group_power {
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atomic_t ref;
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/*
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* CPU power of this group, SCHED_LOAD_SCALE being max power for a
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* single CPU.
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157
kernel/sched.c
157
kernel/sched.c
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@ -6774,10 +6774,36 @@ static struct root_domain *alloc_rootdomain(void)
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return rd;
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}
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static void free_sched_groups(struct sched_group *sg, int free_sgp)
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{
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struct sched_group *tmp, *first;
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if (!sg)
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return;
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first = sg;
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do {
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tmp = sg->next;
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if (free_sgp && atomic_dec_and_test(&sg->sgp->ref))
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kfree(sg->sgp);
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kfree(sg);
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sg = tmp;
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} while (sg != first);
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}
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static void free_sched_domain(struct rcu_head *rcu)
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{
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struct sched_domain *sd = container_of(rcu, struct sched_domain, rcu);
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if (atomic_dec_and_test(&sd->groups->ref)) {
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/*
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* If its an overlapping domain it has private groups, iterate and
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* nuke them all.
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*/
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if (sd->flags & SD_OVERLAP) {
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free_sched_groups(sd->groups, 1);
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} else if (atomic_dec_and_test(&sd->groups->ref)) {
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kfree(sd->groups->sgp);
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kfree(sd->groups);
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}
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@ -6967,15 +6993,73 @@ struct sched_domain_topology_level;
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typedef struct sched_domain *(*sched_domain_init_f)(struct sched_domain_topology_level *tl, int cpu);
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typedef const struct cpumask *(*sched_domain_mask_f)(int cpu);
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#define SDTL_OVERLAP 0x01
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struct sched_domain_topology_level {
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sched_domain_init_f init;
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sched_domain_mask_f mask;
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int flags;
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struct sd_data data;
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};
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/*
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* Assumes the sched_domain tree is fully constructed
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*/
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static int
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build_overlap_sched_groups(struct sched_domain *sd, int cpu)
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{
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struct sched_group *first = NULL, *last = NULL, *groups = NULL, *sg;
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const struct cpumask *span = sched_domain_span(sd);
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struct cpumask *covered = sched_domains_tmpmask;
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struct sd_data *sdd = sd->private;
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struct sched_domain *child;
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int i;
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cpumask_clear(covered);
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for_each_cpu(i, span) {
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struct cpumask *sg_span;
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if (cpumask_test_cpu(i, covered))
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continue;
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sg = kzalloc_node(sizeof(struct sched_group) + cpumask_size(),
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GFP_KERNEL, cpu_to_node(i));
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if (!sg)
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goto fail;
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sg_span = sched_group_cpus(sg);
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child = *per_cpu_ptr(sdd->sd, i);
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if (child->child) {
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child = child->child;
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cpumask_copy(sg_span, sched_domain_span(child));
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} else
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cpumask_set_cpu(i, sg_span);
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cpumask_or(covered, covered, sg_span);
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sg->sgp = *per_cpu_ptr(sdd->sgp, cpumask_first(sg_span));
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atomic_inc(&sg->sgp->ref);
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if (cpumask_test_cpu(cpu, sg_span))
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groups = sg;
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if (!first)
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first = sg;
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if (last)
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last->next = sg;
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last = sg;
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last->next = first;
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}
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sd->groups = groups;
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return 0;
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fail:
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free_sched_groups(first, 0);
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return -ENOMEM;
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}
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static int get_group(int cpu, struct sd_data *sdd, struct sched_group **sg)
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{
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struct sched_domain *sd = *per_cpu_ptr(sdd->sd, cpu);
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@ -6987,23 +7071,21 @@ static int get_group(int cpu, struct sd_data *sdd, struct sched_group **sg)
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if (sg) {
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*sg = *per_cpu_ptr(sdd->sg, cpu);
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(*sg)->sgp = *per_cpu_ptr(sdd->sgp, cpu);
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atomic_set(&(*sg)->sgp->ref, 1); /* for claim_allocations */
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}
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return cpu;
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}
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/*
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* build_sched_groups takes the cpumask we wish to span, and a pointer
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* to a function which identifies what group(along with sched group) a CPU
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* belongs to. The return value of group_fn must be a >= 0 and < nr_cpu_ids
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* (due to the fact that we keep track of groups covered with a struct cpumask).
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*
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* build_sched_groups will build a circular linked list of the groups
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* covered by the given span, and will set each group's ->cpumask correctly,
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* and ->cpu_power to 0.
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*
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* Assumes the sched_domain tree is fully constructed
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*/
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static void
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build_sched_groups(struct sched_domain *sd)
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static int
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build_sched_groups(struct sched_domain *sd, int cpu)
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{
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struct sched_group *first = NULL, *last = NULL;
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struct sd_data *sdd = sd->private;
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@ -7011,6 +7093,12 @@ build_sched_groups(struct sched_domain *sd)
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struct cpumask *covered;
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int i;
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get_group(cpu, sdd, &sd->groups);
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atomic_inc(&sd->groups->ref);
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if (cpu != cpumask_first(sched_domain_span(sd)))
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return 0;
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lockdep_assert_held(&sched_domains_mutex);
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covered = sched_domains_tmpmask;
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@ -7042,6 +7130,8 @@ build_sched_groups(struct sched_domain *sd)
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last = sg;
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}
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last->next = first;
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return 0;
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}
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/*
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@ -7056,13 +7146,18 @@ build_sched_groups(struct sched_domain *sd)
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*/
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static void init_sched_groups_power(int cpu, struct sched_domain *sd)
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{
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WARN_ON(!sd || !sd->groups);
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struct sched_group *sg = sd->groups;
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if (cpu != group_first_cpu(sd->groups))
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WARN_ON(!sd || !sg);
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do {
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sg->group_weight = cpumask_weight(sched_group_cpus(sg));
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sg = sg->next;
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} while (sg != sd->groups);
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if (cpu != group_first_cpu(sg))
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return;
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sd->groups->group_weight = cpumask_weight(sched_group_cpus(sd->groups));
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update_group_power(sd, cpu);
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}
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@ -7182,16 +7277,15 @@ static enum s_alloc __visit_domain_allocation_hell(struct s_data *d,
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static void claim_allocations(int cpu, struct sched_domain *sd)
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{
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struct sd_data *sdd = sd->private;
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struct sched_group *sg = sd->groups;
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WARN_ON_ONCE(*per_cpu_ptr(sdd->sd, cpu) != sd);
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*per_cpu_ptr(sdd->sd, cpu) = NULL;
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if (cpu == cpumask_first(sched_group_cpus(sg))) {
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WARN_ON_ONCE(*per_cpu_ptr(sdd->sg, cpu) != sg);
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if (atomic_read(&(*per_cpu_ptr(sdd->sg, cpu))->ref))
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*per_cpu_ptr(sdd->sg, cpu) = NULL;
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if (atomic_read(&(*per_cpu_ptr(sdd->sgp, cpu))->ref))
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*per_cpu_ptr(sdd->sgp, cpu) = NULL;
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}
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}
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#ifdef CONFIG_SCHED_SMT
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@ -7216,7 +7310,7 @@ static struct sched_domain_topology_level default_topology[] = {
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#endif
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{ sd_init_CPU, cpu_cpu_mask, },
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#ifdef CONFIG_NUMA
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{ sd_init_NODE, cpu_node_mask, },
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{ sd_init_NODE, cpu_node_mask, SDTL_OVERLAP, },
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{ sd_init_ALLNODES, cpu_allnodes_mask, },
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#endif
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{ NULL, },
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@ -7284,7 +7378,9 @@ static void __sdt_free(const struct cpumask *cpu_map)
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struct sd_data *sdd = &tl->data;
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for_each_cpu(j, cpu_map) {
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kfree(*per_cpu_ptr(sdd->sd, j));
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struct sched_domain *sd = *per_cpu_ptr(sdd->sd, j);
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if (sd && (sd->flags & SD_OVERLAP))
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free_sched_groups(sd->groups, 0);
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kfree(*per_cpu_ptr(sdd->sg, j));
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kfree(*per_cpu_ptr(sdd->sgp, j));
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}
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@ -7336,8 +7432,11 @@ static int build_sched_domains(const struct cpumask *cpu_map,
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struct sched_domain_topology_level *tl;
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sd = NULL;
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for (tl = sched_domain_topology; tl->init; tl++)
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for (tl = sched_domain_topology; tl->init; tl++) {
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sd = build_sched_domain(tl, &d, cpu_map, attr, sd, i);
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if (tl->flags & SDTL_OVERLAP || sched_feat(FORCE_SD_OVERLAP))
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sd->flags |= SD_OVERLAP;
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}
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while (sd->child)
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sd = sd->child;
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@ -7349,13 +7448,13 @@ static int build_sched_domains(const struct cpumask *cpu_map,
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for_each_cpu(i, cpu_map) {
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for (sd = *per_cpu_ptr(d.sd, i); sd; sd = sd->parent) {
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sd->span_weight = cpumask_weight(sched_domain_span(sd));
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get_group(i, sd->private, &sd->groups);
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atomic_inc(&sd->groups->ref);
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if (i != cpumask_first(sched_domain_span(sd)))
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continue;
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build_sched_groups(sd);
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if (sd->flags & SD_OVERLAP) {
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if (build_overlap_sched_groups(sd, i))
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goto error;
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} else {
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if (build_sched_groups(sd, i))
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goto error;
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}
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}
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}
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@ -70,3 +70,5 @@ SCHED_FEAT(NONIRQ_POWER, 1)
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* using the scheduler IPI. Reduces rq->lock contention/bounces.
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*/
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SCHED_FEAT(TTWU_QUEUE, 1)
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SCHED_FEAT(FORCE_SD_OVERLAP, 0)
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