linux-kernel - [PATCH v5 04/12] sched: Allow all archs to set the capacity

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Date:	Tue, 26 Aug 2014 13:06:47 +0200
From:	Vincent Guittot <vincent.guittot@...aro.org>
To:	peterz@...radead.org, mingo@...nel.org,
	linux-kernel@...r.kernel.org, preeti@...ux.vnet.ibm.com,
	linux@....linux.org.uk, linux-arm-kernel@...ts.infradead.org
Cc:	riel@...hat.com, Morten.Rasmussen@....com, efault@....de,
	nicolas.pitre@...aro.org, linaro-kernel@...ts.linaro.org,
	daniel.lezcano@...aro.org, dietmar.eggemann@....com,
	Vincent Guittot <vincent.guittot@...aro.org>
Subject: [PATCH v5 04/12] sched: Allow all archs to set the capacity_orig

capacity_orig is only changed for system with a SMT sched_domain level in order
to reflect the lower capacity of CPUs. Heterogenous system also have to reflect an
original capacity that is different from the default value.

Create a more generic function arch_scale_cpu_capacity that can be also used by
non SMT platform to set capacity_orig.

The weak behavior of arch_scale_cpu_capacity is the previous SMT one in order to
keep backward compatibility in the use of capacity_orig.

arch_scale_smt_capacity and default_scale_smt_capacity have been removed as
they were not use elsewhere than in arch_scale_cpu_capacity.

Signed-off-by: Vincent Guittot <vincent.guittot@...aro.org>
---
 kernel/sched/fair.c | 25 ++++++-------------------
 1 file changed, 6 insertions(+), 19 deletions(-)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index b85e9f7..8176bda 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -5705,19 +5705,12 @@ unsigned long __weak arch_scale_freq_capacity(struct sched_domain *sd, int cpu)
 	return default_scale_capacity(sd, cpu);
 }
 
-static unsigned long default_scale_smt_capacity(struct sched_domain *sd, int cpu)
+unsigned long __weak arch_scale_cpu_capacity(struct sched_domain *sd, int cpu)
 {
-	unsigned long weight = sd->span_weight;
-	unsigned long smt_gain = sd->smt_gain;
+	if ((sd->flags & SD_SHARE_CPUCAPACITY) && (sd->span_weight > 1))
+		return sd->smt_gain / sd->span_weight;
 
-	smt_gain /= weight;
-
-	return smt_gain;
-}
-
-unsigned long __weak arch_scale_smt_capacity(struct sched_domain *sd, int cpu)
-{
-	return default_scale_smt_capacity(sd, cpu);
+	return SCHED_CAPACITY_SCALE;
 }
 
 static unsigned long scale_rt_capacity(int cpu)
@@ -5756,18 +5749,12 @@ static unsigned long scale_rt_capacity(int cpu)
 
 static void update_cpu_capacity(struct sched_domain *sd, int cpu)
 {
-	unsigned long weight = sd->span_weight;
 	unsigned long capacity = SCHED_CAPACITY_SCALE;
 	struct sched_group *sdg = sd->groups;
 
-	if ((sd->flags & SD_SHARE_CPUCAPACITY) && weight > 1) {
-		if (sched_feat(ARCH_CAPACITY))
-			capacity *= arch_scale_smt_capacity(sd, cpu);
-		else
-			capacity *= default_scale_smt_capacity(sd, cpu);
+	capacity *= arch_scale_cpu_capacity(sd, cpu);
 
-		capacity >>= SCHED_CAPACITY_SHIFT;
-	}
+	capacity >>= SCHED_CAPACITY_SHIFT;
 
 	sdg->sgc->capacity_orig = capacity;
 
-- 
1.9.1

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