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Subject[RFC PATCH v2 5/6] sched: pack the idle load balance
Date
Look for an idle CPU close to the pack buddy CPU whenever possible.
The goal is to prevent the wake up of a CPU which doesn't share the power
domain of the pack buddy CPU.

Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
---
kernel/sched/fair.c | 18 ++++++++++++++++++
1 file changed, 18 insertions(+)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index f1a4c24..6475f54 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -7274,7 +7274,25 @@ static struct {

static inline int find_new_ilb(int call_cpu)
{
+ struct sched_domain *sd;
int ilb = cpumask_first(nohz.idle_cpus_mask);
+ int buddy = per_cpu(sd_pack_buddy, call_cpu);
+
+ /*
+ * If we have a pack buddy CPU, we try to run load balance on a CPU
+ * that is close to the buddy.
+ */
+ if (buddy != -1)
+ for_each_domain(buddy, sd) {
+ if (sd->flags & SD_SHARE_CPUPOWER)
+ continue;
+
+ ilb = cpumask_first_and(sched_domain_span(sd),
+ nohz.idle_cpus_mask);
+
+ if (ilb < nr_cpu_ids)
+ break;
+ }

if (ilb < nr_cpu_ids && idle_cpu(ilb))
return ilb;
--
1.7.9.5


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