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From 64537223eb2a922fd872741df1a82b1bee325f3e Mon Sep 17 00:00:00 2001
From: Morten Rasmussen <morten.rasmussen@arm.com>
Date: Tue, 3 Feb 2015 13:54:11 +0000
Subject: [PATCH 63/92] sched: Disable energy-unfriendly nohz kicks
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>
(cherry picked from commit a5268e57a1b257dee1ffa9cd9d670ee747a4ec88)
Signed-off-by: Gaku Inami <gaku.inami.xw@bp.renesas.com>
---
kernel/sched/fair.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 360e922..bc347af 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -9150,12 +9150,13 @@ 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
--
1.9.1
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