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authorMorten Rasmussen <morten.rasmussen@arm.com>2015-07-17 14:31:08 +0100
committerJuri Lelli <juri.lelli@arm.com>2015-10-05 12:10:09 +0100
commit34e5ab5f85b3bebe34a617672790c68c3a55449b (patch)
treea5fa1e8658638ec1a429ed533e67291a58b3263e
parentb68d8d477a9797196e2a91f763df17f849535ffe (diff)
downloadlinux-linaro-stable-34e5ab5f85b3bebe34a617672790c68c3a55449b.tar.gz
WIP: sched: Add per-cpu max capacity to sched_group_capacity
struct sched_group_capacity currently represents the compute capacity sum of all cpus in the sched_group. Unless it is divided by the group_weight to get the average capacity per cpu it hides differences in cpu capacity for mixed capacity systems (e.g. high RT/IRQ utilization or ARM big.LITTLE). But even the average may not be sufficient if the group covers cpus of different capacities. Instead, by extending struct sched_group_capacity to indicate max per-cpu capacity in the group a suitable group for a given task utilization can easily be found such that cpus with reduced capacity can be avoided for tasks with high utilization (not implemented by this patch). Change-Id: I3ad0e6df855b1a184db05cb310e91e1e03061467 Signed-off-by: Morten Rasmussen <morten.rasmussen@arm.com>
-rw-r--r--kernel/sched/core.c3
-rw-r--r--kernel/sched/fair.c17
-rw-r--r--kernel/sched/sched.h3
3 files changed, 16 insertions, 7 deletions
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index f449de16983a..8a2db2cc1ab7 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -5418,7 +5418,7 @@ static int sched_domain_debug_one(struct sched_domain *sd, int cpu, int level,
printk(KERN_CONT " %s", str);
if (group->sgc->capacity != SCHED_CAPACITY_SCALE) {
- printk(KERN_CONT " (cpu_capacity = %d)",
+ printk(KERN_CONT " (cpu_capacity = %lu)",
group->sgc->capacity);
}
@@ -5898,6 +5898,7 @@ build_overlap_sched_groups(struct sched_domain *sd, int cpu)
* die on a /0 trap.
*/
sg->sgc->capacity = SCHED_CAPACITY_SCALE * cpumask_weight(sg_span);
+ sg->sgc->max_capacity = SCHED_CAPACITY_SCALE;
sg->sge = *per_cpu_ptr(sdd->sge, i);
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 82dee12f2f01..efed617ef158 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -6391,13 +6391,14 @@ static void update_cpu_capacity(struct sched_domain *sd, int cpu)
cpu_rq(cpu)->cpu_capacity = capacity;
sdg->sgc->capacity = capacity;
+ sdg->sgc->max_capacity = capacity;
}
void update_group_capacity(struct sched_domain *sd, int cpu)
{
struct sched_domain *child = sd->child;
struct sched_group *group, *sdg = sd->groups;
- unsigned long capacity;
+ unsigned long capacity, max_capacity;
unsigned long interval;
interval = msecs_to_jiffies(sd->balance_interval);
@@ -6410,6 +6411,7 @@ void update_group_capacity(struct sched_domain *sd, int cpu)
}
capacity = 0;
+ max_capacity = 0;
if (child->flags & SD_OVERLAP) {
/*
@@ -6434,11 +6436,12 @@ void update_group_capacity(struct sched_domain *sd, int cpu)
*/
if (unlikely(!rq->sd)) {
capacity += capacity_of(cpu);
- continue;
+ } else {
+ sgc = rq->sd->groups->sgc;
+ capacity += sgc->capacity;
}
- sgc = rq->sd->groups->sgc;
- capacity += sgc->capacity;
+ max_capacity = max(capacity, max_capacity);
}
} else {
/*
@@ -6448,12 +6451,16 @@ void update_group_capacity(struct sched_domain *sd, int cpu)
group = child->groups;
do {
- capacity += group->sgc->capacity;
+ struct sched_group_capacity *sgc = group->sgc;
+
+ capacity += sgc->capacity;
+ max_capacity = max(sgc->max_capacity, max_capacity);
group = group->next;
} while (group != child->groups);
}
sdg->sgc->capacity = capacity;
+ sdg->sgc->max_capacity = max_capacity;
}
/*
diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index e3a2d62538a9..a26aa7fd6241 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -771,7 +771,8 @@ struct sched_group_capacity {
* CPU capacity of this group, SCHED_LOAD_SCALE being max capacity
* for a single CPU.
*/
- unsigned int capacity;
+ unsigned long capacity;
+ unsigned long max_capacity; /* Max per-cpu capacity in group */
unsigned long next_update;
int imbalance; /* XXX unrelated to capacity but shared group state */
/*