linux-kernel - [RFCv4 PATCH 19/34] sched: Compute cpu capacity available at current frequency

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Message-Id: <1431459549-18343-20-git-send-email-morten.rasmussen@arm.com>
Date:	Tue, 12 May 2015 20:38:54 +0100
From:	Morten Rasmussen <morten.rasmussen@....com>
To:	peterz@...radead.org, mingo@...hat.com
Cc:	vincent.guittot@...aro.org,
	Dietmar Eggemann <Dietmar.Eggemann@....com>,
	yuyang.du@...el.com, preeti@...ux.vnet.ibm.com,
	mturquette@...aro.org, rjw@...ysocki.net,
	Juri Lelli <Juri.Lelli@....com>, sgurrappadi@...dia.com,
	pang.xunlei@....com.cn, linux-kernel@...r.kernel.org,
	linux-pm@...r.kernel.org, morten.rasmussen@....com
Subject: [RFCv4 PATCH 19/34] sched: Compute cpu capacity available at current frequency

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>
---
 kernel/sched/fair.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 5980bdd..4a8404a 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -4776,6 +4776,17 @@ 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;
+}
+
 static inline bool energy_aware(void)
 {
 	return sched_feat(ENERGY_AWARE);
-- 
1.9.1

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