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[RFCv6 PATCH 01/10] sched: Compute cpu capacity available at current frequency

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  [RFCv6 PATCH 01/10] sched: Compute cpu capacity available at current frequency Steve Muckle <steve.muckle@linaro.org> - 2015-12-09 07:30 +0100

#1287141 — [RFCv6 PATCH 01/10] sched: Compute cpu capacity available at current frequency

From: Morten Rasmussen <morten.rasmussen@arm.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@redhat.com>
cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Morten Rasmussen <morten.rasmussen@arm.com>
Signed-off-by: Steve Muckle <smuckle@linaro.org>
---
 kernel/sched/fair.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 1093873..95b83c4 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -4737,6 +4737,17 @@ 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

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