linux-kernel - [PATCH v2 10/11] sched: move cfs task on a CPU with higher capacity

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Date:	Fri, 23 May 2014 17:53:04 +0200
From:	Vincent Guittot <vincent.guittot@...aro.org>
To:	peterz@...radead.org, mingo@...nel.org,
	linux-kernel@...r.kernel.org, linux@....linux.org.uk,
	linux-arm-kernel@...ts.infradead.org
Cc:	preeti@...ux.vnet.ibm.com, Morten.Rasmussen@....com, efault@....de,
	nicolas.pitre@...aro.org, linaro-kernel@...ts.linaro.org,
	daniel.lezcano@...aro.org,
	Vincent Guittot <vincent.guittot@...aro.org>
Subject: [PATCH v2 10/11] sched: move cfs task on a CPU with higher capacity

If the CPU is used for handling lot of IRQs, trig a load balance to check if
it's worth moving its tasks on another CPU that has more capacity

Signed-off-by: Vincent Guittot <vincent.guittot@...aro.org>
---
 kernel/sched/fair.c | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index e8a30f9..2501e49 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -5948,6 +5948,13 @@ static bool update_sd_pick_busiest(struct lb_env *env,
 	if (sgs->sum_nr_running > sgs->group_capacity)
 		return true;
 
+	/*
+	 * The group capacity is reduced probably because of activity from other
+	 * sched class or interrupts which use part of the available capacity
+	 */
+	if ((sg->sgp->power_orig * 100) > (sgs->group_power * env->sd->imbalance_pct))
+		return true;
+
 	if (sgs->group_imb)
 		return true;
 
@@ -7282,6 +7289,12 @@ static inline int nohz_kick_needed(struct rq *rq)
 
 		if (nr_busy > 1)
 			goto need_kick_unlock;
+
+		if ((rq->cfs.h_nr_running >= 1)
+		 && ((rq->cpu_power * sd->imbalance_pct) <
+					(rq->cpu_power_orig * 100)))
+			goto need_kick_unlock;
+
 	}
 
 	sd = rcu_dereference(per_cpu(sd_asym, cpu));
-- 
1.9.1

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