linux-kernel - [PATCH] sched/fair: fix runnable

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Date:   Wed, 26 Feb 2020 19:16:40 +0100
From:   Vincent Guittot <vincent.guittot@...aro.org>
To:     mingo@...hat.com, peterz@...radead.org, juri.lelli@...hat.com,
        dietmar.eggemann@....com, rostedt@...dmis.org, bsegall@...gle.com,
        mgorman@...e.de, linux-kernel@...r.kernel.org
Cc:     pauld@...hat.com, parth@...ux.ibm.com, valentin.schneider@....com,
        hdanton@...a.com, zhout@...aldi.net,
        Vincent Guittot <vincent.guittot@...aro.org>
Subject: [PATCH] sched/fair: fix runnable_avg for throttled cfs

When a cfs_rq is throttled, its group entity is dequeued and its running
tasks are removed. We must update runnable_avg with current h_nr_running
and update group_se->runnable_weight with new h_nr_running at each level
of the hierarchy.

Fixes: 9f68395333ad ("sched/pelt: Add a new runnable average signal")
Signed-off-by: Vincent Guittot <vincent.guittot@...aro.org>
---
This patch applies on top of tip/sched/core

 kernel/sched/fair.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index fcc968669aea..6d46974e9be7 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -4703,6 +4703,11 @@ static void throttle_cfs_rq(struct cfs_rq *cfs_rq)
 
 		if (dequeue)
 			dequeue_entity(qcfs_rq, se, DEQUEUE_SLEEP);
+		else {
+			update_load_avg(qcfs_rq, se, 0);
+			se_update_runnable(se);
+		}
+
 		qcfs_rq->h_nr_running -= task_delta;
 		qcfs_rq->idle_h_nr_running -= idle_task_delta;
 
@@ -4772,6 +4777,11 @@ void unthrottle_cfs_rq(struct cfs_rq *cfs_rq)
 		cfs_rq = cfs_rq_of(se);
 		if (enqueue)
 			enqueue_entity(cfs_rq, se, ENQUEUE_WAKEUP);
+		else {
+			update_load_avg(cfs_rq, se, 0);
+			se_update_runnable(se);
+		}
+
 		cfs_rq->h_nr_running += task_delta;
 		cfs_rq->idle_h_nr_running += idle_task_delta;
 
-- 
2.17.1