linux-kernel - [PATCH] sched/fair: enqueue_task

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Message-Id: <20200511192301.1009-1-vincent.guittot@linaro.org>
Date:   Mon, 11 May 2020 21:23:01 +0200
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, pauld@...hat.com,
        ouwen210@...mail.com
Cc:     Vincent Guittot <vincent.guittot@...aro.org>
Subject: [PATCH] sched/fair: enqueue_task_fair optimization

enqueue_task_fair() jumps to enqueue_throttle when cfs_rq_of(se) is
throttled, which means that se can't be NULL and we can skip the test.

Signed-off-by: Vincent Guittot <vincent.guittot@...aro.org>
---
 kernel/sched/fair.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 4b73518aa25c..910bbbe50365 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -5512,7 +5512,6 @@ enqueue_task_fair(struct rq *rq, struct task_struct *p, int flags)
                        list_add_leaf_cfs_rq(cfs_rq);
 	}
 
-enqueue_throttle:
 	if (!se) {
 		add_nr_running(rq, 1);
 		/*
@@ -5534,6 +5533,7 @@ enqueue_task_fair(struct rq *rq, struct task_struct *p, int flags)
 
 	}
 
+enqueue_throttle:
 	if (cfs_bandwidth_used()) {
 		/*
 		 * When bandwidth control is enabled; the cfs_rq_throttled()
-- 
2.17.1