linux-kernel - [PATCH v2] sched: Check sched_domain before computing group power.

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Message-ID: <20131112164126.GF2559@linux.vnet.ibm.com>
Date:	Tue, 12 Nov 2013 22:11:26 +0530
From:	Srikar Dronamraju <srikar@...ux.vnet.ibm.com>
To:	Peter Zijlstra <peterz@...radead.org>
Cc:	mingo@...nel.org, hpa@...or.com, linux-kernel@...r.kernel.org,
	tglx@...utronix.de, mikey@...ling.org,
	linux-tip-commits@...r.kernel.org
Subject: [PATCH v2] sched: Check sched_domain before computing group power.

After Commit-id 863bffc80898 (sched/fair: Fix group power_orig
computation), we might end up computing group power before the
sched_domain for a cpu is updated.

Update with cpu_power, if rq->sd is not yet updated.

Signed-off-by: Srikar Dronamraju <srikar@...ux.vnet.ibm.com>
---
Changelog since v1: Fix divide by zero errors that can result because
power/power_orig was set to 0.

 kernel/sched/fair.c |   10 +++++++++-
 1 files changed, 9 insertions(+), 1 deletions(-)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index df77c60..8d92853 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -5354,8 +5354,16 @@ void update_group_power(struct sched_domain *sd, int cpu)
 		 */
 
 		for_each_cpu(cpu, sched_group_cpus(sdg)) {
-			struct sched_group *sg = cpu_rq(cpu)->sd->groups;
+			struct rq *rq = cpu_rq(cpu);
+			struct sched_group *sg;
 
+			if (!rq->sd) {
+				power_orig += power_of(cpu);
+				power += power_of(cpu);
+				continue;
+			}
+
+			sg = rq->sd->groups;
 			power_orig += sg->sgp->power_orig;
 			power += sg->sgp->power;
 		}
-- 
1.7.1

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