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From: Vincent Guittot <vincent.guittot@linaro.org>
To: mingo@redhat.com, peterz@infradead.org, juri.lelli@redhat.com,
	dietmar.eggemann@arm.com, rostedt@goodmis.org,
	bsegall@google.com, mgorman@suse.de,
	linux-kernel@vger.kernel.org
Cc: pauld@redhat.com, parth@linux.ibm.com,
	valentin.schneider@arm.com, hdanton@sina.com,
	quentin.perret@arm.com, srikar@linux.vnet.ibm.com,
	riel@surriel.com, Morten.Rasmussen@arm.com,
	Vincent Guittot <vincent.guittot@linaro.org>
Subject: [PATCH] sched/fair: fix statistics for find_idlest_group()
Date: Tue, 18 Feb 2020 15:45:34 +0100
Message-ID: <20200218144534.4564-1-vincent.guittot@linaro.org> (raw)

sgs->group_weight is not set while gathering statistics in
update_sg_wakeup_stats(). This means that a group can be classified as
fully busy with 0 running tasks if utilization is high enough.

This path is mainly used for fork and exec.

Fixes: 57abff067a08 ("sched/fair: Rework find_idlest_group()")
Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
---
 kernel/sched/fair.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index a7e11b1bb64c..643ed6d8b8ff 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -8354,6 +8354,8 @@ static inline void update_sg_wakeup_stats(struct sched_domain *sd,
 
 	sgs->group_capacity = group->sgc->capacity;
 
+	sgs->group_weight = group->group_weight;
+
 	sgs->group_type = group_classify(sd->imbalance_pct, group, sgs);
 
 	/*
-- 
2.17.1


             reply index

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-02-18 14:45 Vincent Guittot [this message]
2020-02-18 15:09 ` Peter Zijlstra
2020-02-27  9:12 ` [tip: sched/urgent] sched/fair: Fix " tip-bot2 for Vincent Guittot

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