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sched: Ignore offline CPUs in HMP migration & load stats

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Previously, an offline CPU would always appear to have a zero load
and this would distort the offload functionality used for balancing
big and little domains.

Maintain a mask of online CPUs in each domain and use this instead.

Change-Id: I639b564b2f40cb659af8ceb8bd37f84b8a1fe323
Signed-off-by: Chris Redpath <chris.redpath@arm.com>
This commit is contained in:
Chris Redpath
2013-05-16 17:48:24 +01:00
committed by Jon Medhurst
parent d2c920023c
commit b64cc6f7e5
3 changed files with 42 additions and 4 deletions
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6
arch/arm/kernel/topology.c
View File

@@ -383,12 +383,14 @@ void __init arch_get_hmp_domains(struct list_head *hmp_domains_list)
if(!cpumask_empty(&hmp_slow_cpu_mask)) {
domain = (struct hmp_domain *)
kmalloc(sizeof(struct hmp_domain), GFP_KERNEL);
cpumask_copy(&domain->cpus, &hmp_slow_cpu_mask);
cpumask_copy(&domain->possible_cpus, &hmp_slow_cpu_mask);
cpumask_and(&domain->cpus, cpu_online_mask, &domain->possible_cpus);
list_add(&domain->hmp_domains, hmp_domains_list);
}
domain = (struct hmp_domain *)
kmalloc(sizeof(struct hmp_domain), GFP_KERNEL);
cpumask_copy(&domain->cpus, &hmp_fast_cpu_mask);
cpumask_copy(&domain->possible_cpus, &hmp_fast_cpu_mask);
cpumask_and(&domain->cpus, cpu_online_mask, &domain->possible_cpus);
list_add(&domain->hmp_domains, hmp_domains_list);
}
#endif /* CONFIG_SCHED_HMP */

1
include/linux/sched.h
View File

@@ -888,6 +888,7 @@ bool cpus_share_cache(int this_cpu, int that_cpu);
#ifdef CONFIG_SCHED_HMP
struct hmp_domain {
struct cpumask cpus;
struct cpumask possible_cpus;
struct list_head hmp_domains;
};
#endif /* CONFIG_SCHED_HMP */

39
kernel/sched/fair.c
View File

@@ -3381,10 +3381,10 @@ static int __init hmp_cpu_mask_setup(void)
dc = 0;
list_for_each(pos, &hmp_domains) {
domain = list_entry(pos, struct hmp_domain, hmp_domains);
cpulist_scnprintf(buf, 64, &domain->cpus);
cpulist_scnprintf(buf, 64, &domain->possible_cpus);
pr_debug(" HMP domain %d: %s\n", dc, buf);
for_each_cpu_mask(cpu, domain->cpus) {
for_each_cpu_mask(cpu, domain->possible_cpus) {
per_cpu(hmp_cpu_domain, cpu) = domain;
}
dc++;
@@ -3393,6 +3393,35 @@ static int __init hmp_cpu_mask_setup(void)
return 1;
}
static struct hmp_domain *hmp_get_hmp_domain_for_cpu(int cpu)
{
struct hmp_domain *domain;
struct list_head *pos;
list_for_each(pos, &hmp_domains) {
domain = list_entry(pos, struct hmp_domain, hmp_domains);
if(cpumask_test_cpu(cpu, &domain->possible_cpus))
return domain;
}
return NULL;
}
static void hmp_online_cpu(int cpu)
{
struct hmp_domain *domain = hmp_get_hmp_domain_for_cpu(cpu);
if(domain)
cpumask_set_cpu(cpu, &domain->cpus);
}
static void hmp_offline_cpu(int cpu)
{
struct hmp_domain *domain = hmp_get_hmp_domain_for_cpu(cpu);
if(domain)
cpumask_clear_cpu(cpu, &domain->cpus);
}
/*
* Migration thresholds should be in the range [0..1023]
* hmp_up_threshold: min. load required for migrating tasks to a faster cpu
@@ -6190,11 +6219,17 @@ void trigger_load_balance(struct rq *rq, int cpu)
static void rq_online_fair(struct rq *rq)
{
#ifdef CONFIG_SCHED_HMP
hmp_online_cpu(rq->cpu);
#endif
update_sysctl();
}
static void rq_offline_fair(struct rq *rq)
{
#ifdef CONFIG_SCHED_HMP
hmp_offline_cpu(rq->cpu);
#endif
update_sysctl();
/* Ensure any throttled groups are reachable by pick_next_task */