linux-kernel - [PATCH RFC 1/7] sched: Make energy awareness a sched feature

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Date:	Tue, 21 Oct 2014 23:07:25 -0700
From:	Mike Turquette <mturquette@...aro.org>
To:	peterz@...radead.org, mingo@...nel.org
Cc:	linux-kernel@...r.kernel.org, preeti@...ux.vnet.ibm.com,
	Morten.Rasmussen@....com, kamalesh@...ux.vnet.ibm.com,
	riel@...hat.com, efault@....de, nicolas.pitre@...aro.org,
	linaro-kernel@...ts.linaro.org, daniel.lezcano@...aro.org,
	dietmar.eggemann@....com, pjt@...gle.com, bsegall@...gle.com,
	vincent.guittot@...aro.org, patches@...aro.org,
	tuukka.tikkanen@...aro.org, amit.kucheria@...aro.org,
	Morten Rasmussen <morten.rasmussen@....com>,
	Mike Turquette <mturquette@...aro.org>
Subject: [PATCH RFC 1/7] sched: Make energy awareness a sched feature

From: Morten Rasmussen <morten.rasmussen@....com>

This patch introduces the ENERGY_AWARE sched feature, which is
implemented using jump labels when SCHED_DEBUG is defined. It is
statically set false when SCHED_DEBUG is not defined. Hence this doesn't
allow energy awareness to be enabled without SCHED_DEBUG. This
sched_feature knob will be replaced later with a more appropriate
control knob when things have matured a bit.

Signed-off-by: Morten Rasmussen <morten.rasmussen@....com>
Signed-off-by: Mike Turquette <mturquette@...aro.org>
[mturquette@...aro.org: moved energy_aware above enqueue_task_fair]
---
 kernel/sched/fair.c     | 5 +++++
 kernel/sched/features.h | 6 ++++++
 2 files changed, 11 insertions(+)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 6738160..90b36cc 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -3978,6 +3978,11 @@ static inline void hrtick_update(struct rq *rq)
 }
 #endif
 
+static inline bool energy_aware(void)
+{
+	return sched_feat(ENERGY_AWARE);
+}
+
 /*
  * The enqueue_task method is called before nr_running is
  * increased. Here we update the fair scheduling stats and
diff --git a/kernel/sched/features.h b/kernel/sched/features.h
index 90284d1..199ee3a 100644
--- a/kernel/sched/features.h
+++ b/kernel/sched/features.h
@@ -83,3 +83,9 @@ SCHED_FEAT(NUMA_FAVOUR_HIGHER, true)
  */
 SCHED_FEAT(NUMA_RESIST_LOWER, false)
 #endif
+
+/*
+ * Energy aware scheduling. Use platform energy model to guide scheduling
+ * decisions optimizing for energy efficiency.
+ */
+SCHED_FEAT(ENERGY_AWARE, false)
-- 
1.8.3.2

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