linux-kernel - [RFCv7 PATCH 01/10] sched: Compute cpu capacity available at current frequency

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Message-Id: <1456190570-4475-2-git-send-email-smuckle@linaro.org>
Date:	Mon, 22 Feb 2016 17:22:41 -0800
From:	Steve Muckle <steve.muckle@...aro.org>
To:	Peter Zijlstra <peterz@...radead.org>,
	Ingo Molnar <mingo@...hat.com>,
	"Rafael J. Wysocki" <rafael@...nel.org>
Cc:	linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org,
	Vincent Guittot <vincent.guittot@...aro.org>,
	Morten Rasmussen <morten.rasmussen@....com>,
	Dietmar Eggemann <dietmar.eggemann@....com>,
	Juri Lelli <Juri.Lelli@....com>,
	Patrick Bellasi <patrick.bellasi@....com>,
	Michael Turquette <mturquette@...libre.com>
Subject: [RFCv7 PATCH 01/10] sched: Compute cpu capacity available at current frequency

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

capacity_orig_of() returns the max available compute capacity of a cpu.
For scale-invariant utilization tracking and energy-aware scheduling
decisions it is useful to know the compute capacity available at the
current OPP of a cpu.

cc: Ingo Molnar <mingo@...hat.com>
cc: Peter Zijlstra <peterz@...radead.org>
Signed-off-by: Morten Rasmussen <morten.rasmussen@....com>
Signed-off-by: Steve Muckle <smuckle@...aro.org>
---
 kernel/sched/fair.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 7ce24a4..3437e01 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -4821,6 +4821,17 @@ static long effective_load(struct task_group *tg, int cpu, long wl, long wg)
 #endif
 
 /*
+ * Returns the current capacity of cpu after applying both
+ * cpu and freq scaling.
+ */
+static unsigned long capacity_curr_of(int cpu)
+{
+	return cpu_rq(cpu)->cpu_capacity_orig *
+	       arch_scale_freq_capacity(NULL, cpu)
+	       >> SCHED_CAPACITY_SHIFT;
+}
+
+/*
  * Detect M:N waker/wakee relationships via a switching-frequency heuristic.
  * A waker of many should wake a different task than the one last awakened
  * at a frequency roughly N times higher than one of its wakees.  In order
-- 
2.4.10