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Date: Wed, 20 Jul 2011 17:29:08 GMT
From: tip-bot for Peter Zijlstra <a.p.zijlstra@...llo.nl>
To: linux-tip-commits@...r.kernel.org
Cc: linux-kernel@...r.kernel.org, anton@...ba.org, hpa@...or.com,
mingo@...hat.com, torvalds@...ux-foundation.org,
a.p.zijlstra@...llo.nl, akpm@...ux-foundation.org,
tglx@...utronix.de, mingo@...e.hu
Subject: [tip:sched/urgent] sched: Allow for overlapping sched_domain spans
Commit-ID: e3589f6c81e4764d32a25d2a2a0afe54fa344f5c
Gitweb: http://git.kernel.org/tip/e3589f6c81e4764d32a25d2a2a0afe54fa344f5c
Author: Peter Zijlstra <a.p.zijlstra@...llo.nl>
AuthorDate: Fri, 15 Jul 2011 10:35:52 +0200
Committer: Ingo Molnar <mingo@...e.hu>
CommitDate: Wed, 20 Jul 2011 18:32:41 +0200
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@...ba.org>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@...llo.nl>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Andrew Morton <akpm@...ux-foundation.org>
Link: http://lkml.kernel.org/n/tip-08bxqw9wis3qti9u5inifh3y@git.kernel.org
Signed-off-by: Ingo Molnar <mingo@...e.hu>
---
include/linux/sched.h | 2 +
kernel/sched.c | 157 ++++++++++++++++++++++++++++++++++++++---------
kernel/sched_features.h | 2 +
3 files changed, 132 insertions(+), 29 deletions(-)
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 2e5b3c8..bde99d5 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -844,6 +844,7 @@ enum cpu_idle_type {
#define SD_SERIALIZE 0x0400 /* Only a single load balancing instance */
#define SD_ASYM_PACKING 0x0800 /* Place busy groups earlier in the domain */
#define SD_PREFER_SIBLING 0x1000 /* Prefer to place tasks in a sibling domain */
+#define SD_OVERLAP 0x2000 /* sched_domains of this level overlap */
enum powersavings_balance_level {
POWERSAVINGS_BALANCE_NONE = 0, /* No power saving load balance */
@@ -894,6 +895,7 @@ static inline int sd_power_saving_flags(void)
}
struct sched_group_power {
+ atomic_t ref;
/*
* CPU power of this group, SCHED_LOAD_SCALE being max power for a
* single CPU.
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 @@ static struct root_domain *alloc_rootdomain(void)
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 @@ struct sched_domain_topology_level;
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 @@ static int get_group(int cpu, struct sd_data *sdd, struct sched_group **sg)
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 @@ build_sched_groups(struct sched_domain *sd)
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 @@ build_sched_groups(struct sched_domain *sd)
last = sg;
}
last->next = first;
+
+ return 0;
}
/*
@@ -7056,12 +7146,17 @@ build_sched_groups(struct sched_domain *sd)
*/
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))
- return;
+ WARN_ON(!sd || !sg);
+
+ do {
+ sg->group_weight = cpumask_weight(sched_group_cpus(sg));
+ sg = sg->next;
+ } while (sg != sd->groups);
- sd->groups->group_weight = cpumask_weight(sched_group_cpus(sd->groups));
+ if (cpu != group_first_cpu(sg))
+ return;
update_group_power(sd, cpu);
}
@@ -7182,16 +7277,15 @@ static enum s_alloc __visit_domain_allocation_hell(struct s_data *d,
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 @@ static struct sched_domain_topology_level default_topology[] = {
#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 @@ static void __sdt_free(const struct cpumask *cpu_map)
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 @@ static int build_sched_domains(const struct cpumask *cpu_map,
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 @@ static int build_sched_domains(const struct cpumask *cpu_map,
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;
+ }
}
}
diff --git a/kernel/sched_features.h b/kernel/sched_features.h
index be40f73..1e7066d 100644
--- a/kernel/sched_features.h
+++ b/kernel/sched_features.h
@@ -70,3 +70,5 @@ SCHED_FEAT(NONIRQ_POWER, 1)
* using the scheduler IPI. Reduces rq->lock contention/bounces.
*/
SCHED_FEAT(TTWU_QUEUE, 1)
+
+SCHED_FEAT(FORCE_SD_OVERLAP, 0)
--
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