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ANDROID: sched: Disable energy-unfriendly nohz kicks

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With energy-aware scheduling enabled nohz_kick_needed() generates many
nohz idle-balance kicks which lead to nothing when multiple tasks get
packed on a single cpu to save energy. This causes unnecessary wake-ups
and hence wastes energy. Make these conditions depend on !energy_aware()
for now until the energy-aware nohz story gets sorted out.

cc: Ingo Molnar <mingo@redhat.com>
cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Morten Rasmussen <morten.rasmussen@arm.com>
Signed-off-by: Andres Oportus <andresoportus@google.com>
This commit is contained in:
Morten Rasmussen
2015-02-03 13:54:11 +00:00
committed by Dmitry Shmidt
parent 53065e82a1
commit f69e2dc550
1 changed files with 3 additions and 2 deletions
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5
kernel/sched/fair.c
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@@ -8928,12 +8928,13 @@ static inline bool nohz_kick_needed(struct rq *rq)
if (time_before(now, nohz.next_balance))
return false;
if (rq->nr_running >= 2)
if (rq->nr_running >= 2 &&
(!energy_aware() || cpu_overutilized(cpu)))
return true;
rcu_read_lock();
sds = rcu_dereference(per_cpu(sd_llc_shared, cpu));
if (sds) {
if (sds && !energy_aware()) {
/*
* XXX: write a coherent comment on why we do this.
* See also: http://lkml.kernel.org/r/20111202010832.602203411@sbsiddha-desk.sc.intel.com