ANDROID: sched: Make energy awareness a sched feature

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.

ENERGY_AWARE is based on per-entity load-tracking hence FAIR_GROUP_SCHED
must be enable. This dependency isn't checked at compile time yet.

cc: Ingo Molnar <mingo@redhat.com>
cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Morten Rasmussen <morten.rasmussen@arm.com>
Change-Id: Ib94ec79f7f5820dfaed515ede548afe2936c15c6
Signed-off-by: Chris Redpath <chris.redpath@arm.com>

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 509cd715ab81af88f0f402e0b0ba48fcac5b1d98..98ce04fb66f9df90c5c8edd2e5dd4fe5ad5fe0fa 100644 (file)
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -5327,6 +5327,11 @@ static void record_wakee(struct task_struct *p)
        }
 }
 
+static inline bool energy_aware(void)
+{
+       return sched_feat(ENERGY_AWARE);
+}
+
 /*
  * Detect M:N waker/wakee relationships via a switching-frequency heuristic.
  *

diff --git a/kernel/sched/features.h b/kernel/sched/features.h
index 9552fd5854bffc2c07ec77225a1aed9176da53cb..8be01be159f6df67b5d036fccb90bdfd741fb11e 100644 (file)
--- a/kernel/sched/features.h
+++ b/kernel/sched/features.h
@@ -85,3 +85,9 @@ SCHED_FEAT(ATTACH_AGE_LOAD, true)
 SCHED_FEAT(WA_IDLE, true)
 SCHED_FEAT(WA_WEIGHT, true)
 SCHED_FEAT(WA_BIAS, true)
+
+/*
+ * Energy aware scheduling. Use platform energy model to guide scheduling
+ * decisions optimizing for energy efficiency.
+ */
+SCHED_FEAT(ENERGY_AWARE, false)