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sched: Add per-cpu max capacity to sched_group_capacity

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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).

Signed-off-by: Morten Rasmussen <morten.rasmussen@arm.com>
This commit is contained in:
Morten Rasmussen
2016-02-25 12:43:49 +00:00
committed by Leo Yan
parent e14f151823
commit 563ddb604e
3 changed files with 16 additions and 7 deletions
Download Patch File Download Diff File Expand all files Collapse all files

3
kernel/sched/core.c
View File

@@ -5714,7 +5714,7 @@ static int sched_domain_debug_one(struct sched_domain *sd, int cpu, int level,
printk(KERN_CONT " %*pbl",
cpumask_pr_args(sched_group_cpus(group)));
if (group->sgc->capacity != SCHED_CAPACITY_SCALE) {
printk(KERN_CONT " (cpu_capacity = %d)",
printk(KERN_CONT " (cpu_capacity = %lu)",
group->sgc->capacity);
}
@@ -6193,6 +6193,7 @@ 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;
/*
* Make sure the first group of this domain contains the

17
kernel/sched/fair.c
View File

@@ -6609,13 +6609,14 @@ skip_unlock: __attribute__ ((unused));
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);
@@ -6628,6 +6629,7 @@ void update_group_capacity(struct sched_domain *sd, int cpu)
}
capacity = 0;
max_capacity = 0;
if (child->flags & SD_OVERLAP) {
/*
@@ -6652,11 +6654,12 @@ 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 {
/*
@@ -6666,12 +6669,16 @@ 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;
}
/*

3
kernel/sched/sched.h
View File

@@ -858,7 +858,8 @@ 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 */
/*