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>
diff --git a/kernel/sched.c b/kernel/sched.c
index 36c10d2..921adf6 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -6774,10 +6774,36 @@
return rd;
}
+static void free_sched_groups(struct sched_group *sg, int free_sgp)
+{
+ struct sched_group *tmp, *first;
+
+ if (!sg)
+ return;
+
+ first = sg;
+ do {
+ tmp = sg->next;
+
+ if (free_sgp && atomic_dec_and_test(&sg->sgp->ref))
+ kfree(sg->sgp);
+
+ kfree(sg);
+ sg = tmp;
+ } while (sg != first);
+}
+
static void free_sched_domain(struct rcu_head *rcu)
{
struct sched_domain *sd = container_of(rcu, struct sched_domain, rcu);
- if (atomic_dec_and_test(&sd->groups->ref)) {
+
+ /*
+ * If its an overlapping domain it has private groups, iterate and
+ * nuke them all.
+ */
+ if (sd->flags & SD_OVERLAP) {
+ free_sched_groups(sd->groups, 1);
+ } else if (atomic_dec_and_test(&sd->groups->ref)) {
kfree(sd->groups->sgp);
kfree(sd->groups);
}
@@ -6967,15 +6993,73 @@
typedef struct sched_domain *(*sched_domain_init_f)(struct sched_domain_topology_level *tl, int cpu);
typedef const struct cpumask *(*sched_domain_mask_f)(int cpu);
+#define SDTL_OVERLAP 0x01
+
struct sched_domain_topology_level {
sched_domain_init_f init;
sched_domain_mask_f mask;
+ int flags;
struct sd_data data;
};
-/*
- * Assumes the sched_domain tree is fully constructed
- */
+static int
+build_overlap_sched_groups(struct sched_domain *sd, int cpu)
+{
+ struct sched_group *first = NULL, *last = NULL, *groups = 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 *child;
+ int i;
+
+ cpumask_clear(covered);
+
+ for_each_cpu(i, span) {
+ struct cpumask *sg_span;
+
+ if (cpumask_test_cpu(i, covered))
+ continue;
+
+ sg = kzalloc_node(sizeof(struct sched_group) + cpumask_size(),
+ GFP_KERNEL, cpu_to_node(i));
+
+ if (!sg)
+ goto fail;
+
+ sg_span = sched_group_cpus(sg);
+
+ child = *per_cpu_ptr(sdd->sd, i);
+ if (child->child) {
+ child = child->child;
+ cpumask_copy(sg_span, sched_domain_span(child));
+ } else
+ cpumask_set_cpu(i, sg_span);
+
+ cpumask_or(covered, covered, sg_span);
+
+ sg->sgp = *per_cpu_ptr(sdd->sgp, cpumask_first(sg_span));
+ atomic_inc(&sg->sgp->ref);
+
+ if (cpumask_test_cpu(cpu, sg_span))
+ groups = sg;
+
+ if (!first)
+ first = sg;
+ if (last)
+ last->next = sg;
+ last = sg;
+ last->next = first;
+ }
+ sd->groups = groups;
+
+ return 0;
+
+fail:
+ free_sched_groups(first, 0);
+
+ return -ENOMEM;
+}
+
static int get_group(int cpu, struct sd_data *sdd, struct sched_group **sg)
{
struct sched_domain *sd = *per_cpu_ptr(sdd->sd, cpu);
@@ -6987,23 +7071,21 @@
if (sg) {
*sg = *per_cpu_ptr(sdd->sg, cpu);
(*sg)->sgp = *per_cpu_ptr(sdd->sgp, cpu);
+ atomic_set(&(*sg)->sgp->ref, 1); /* for claim_allocations */
}
return cpu;
}
/*
- * build_sched_groups takes the cpumask we wish to span, and a pointer
- * to a function which identifies what group(along with sched group) a CPU
- * belongs to. The return value of group_fn must be a >= 0 and < nr_cpu_ids
- * (due to the fact that we keep track of groups covered with a struct cpumask).
- *
* 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_power to 0.
+ *
+ * Assumes the sched_domain tree is fully constructed
*/
-static void
-build_sched_groups(struct sched_domain *sd)
+static int
+build_sched_groups(struct sched_domain *sd, int cpu)
{
struct sched_group *first = NULL, *last = NULL;
struct sd_data *sdd = sd->private;
@@ -7011,6 +7093,12 @@
struct cpumask *covered;
int i;
+ get_group(cpu, sdd, &sd->groups);
+ atomic_inc(&sd->groups->ref);
+
+ if (cpu != cpumask_first(sched_domain_span(sd)))
+ return 0;
+
lockdep_assert_held(&sched_domains_mutex);
covered = sched_domains_tmpmask;
@@ -7042,6 +7130,8 @@
last = sg;
}
last->next = first;
+
+ return 0;
}
/*
@@ -7056,13 +7146,18 @@
*/
static void init_sched_groups_power(int cpu, struct sched_domain *sd)
{
- WARN_ON(!sd || !sd->groups);
+ struct sched_group *sg = sd->groups;
- if (cpu != group_first_cpu(sd->groups))
+ WARN_ON(!sd || !sg);
+
+ do {
+ sg->group_weight = cpumask_weight(sched_group_cpus(sg));
+ sg = sg->next;
+ } while (sg != sd->groups);
+
+ if (cpu != group_first_cpu(sg))
return;
- sd->groups->group_weight = cpumask_weight(sched_group_cpus(sd->groups));
-
update_group_power(sd, cpu);
}
@@ -7182,16 +7277,15 @@
static void claim_allocations(int cpu, struct sched_domain *sd)
{
struct sd_data *sdd = sd->private;
- struct sched_group *sg = sd->groups;
WARN_ON_ONCE(*per_cpu_ptr(sdd->sd, cpu) != sd);
*per_cpu_ptr(sdd->sd, cpu) = NULL;
- if (cpu == cpumask_first(sched_group_cpus(sg))) {
- WARN_ON_ONCE(*per_cpu_ptr(sdd->sg, cpu) != sg);
+ if (atomic_read(&(*per_cpu_ptr(sdd->sg, cpu))->ref))
*per_cpu_ptr(sdd->sg, cpu) = NULL;
+
+ if (atomic_read(&(*per_cpu_ptr(sdd->sgp, cpu))->ref))
*per_cpu_ptr(sdd->sgp, cpu) = NULL;
- }
}
#ifdef CONFIG_SCHED_SMT
@@ -7216,7 +7310,7 @@
#endif
{ sd_init_CPU, cpu_cpu_mask, },
#ifdef CONFIG_NUMA
- { sd_init_NODE, cpu_node_mask, },
+ { sd_init_NODE, cpu_node_mask, SDTL_OVERLAP, },
{ sd_init_ALLNODES, cpu_allnodes_mask, },
#endif
{ NULL, },
@@ -7284,7 +7378,9 @@
struct sd_data *sdd = &tl->data;
for_each_cpu(j, cpu_map) {
- kfree(*per_cpu_ptr(sdd->sd, j));
+ struct sched_domain *sd = *per_cpu_ptr(sdd->sd, j);
+ if (sd && (sd->flags & SD_OVERLAP))
+ free_sched_groups(sd->groups, 0);
kfree(*per_cpu_ptr(sdd->sg, j));
kfree(*per_cpu_ptr(sdd->sgp, j));
}
@@ -7336,8 +7432,11 @@
struct sched_domain_topology_level *tl;
sd = NULL;
- for (tl = sched_domain_topology; tl->init; tl++)
+ for (tl = sched_domain_topology; tl->init; tl++) {
sd = build_sched_domain(tl, &d, cpu_map, attr, sd, i);
+ if (tl->flags & SDTL_OVERLAP || sched_feat(FORCE_SD_OVERLAP))
+ sd->flags |= SD_OVERLAP;
+ }
while (sd->child)
sd = sd->child;
@@ -7349,13 +7448,13 @@
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));
- get_group(i, sd->private, &sd->groups);
- atomic_inc(&sd->groups->ref);
-
- if (i != cpumask_first(sched_domain_span(sd)))
- continue;
-
- build_sched_groups(sd);
+ if (sd->flags & SD_OVERLAP) {
+ if (build_overlap_sched_groups(sd, i))
+ goto error;
+ } else {
+ if (build_sched_groups(sd, i))
+ goto error;
+ }
}
}