linux-kernel - [PATCH] sched: don't check rq after newidle

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Message-Id: <1608014930-5144-1-git-send-email-xiaoggchen@tencent.com>
Date:   Tue, 15 Dec 2020 14:48:50 +0800
From:   chenxg1x@...il.com
To:     linux-kernel@...r.kernel.org
Cc:     mingo@...hat.com, peterz@...radead.org, juri.lelli@...hat.com,
        vincent.guittot@...aro.org, dietmar.eggemann@....com,
        rostedt@...dmis.org, bsegall@...gle.com, mgorman@...e.de,
        bristot@...hat.com, heddchen@...cent.com, xiaoggchen@...cent.com
Subject: [PATCH] sched: don't check rq after newidle_balance return positive

From: Chen Xiaoguang <xiaoggchen@...cent.com>

In pick_next_task_fair, if CPU is going to idle newidle_balance
is called first trying to pull some tasks.
When newidle_balance returns positive which means it does
pulls tasks or some tasks enqueued then there is no need to check
sched_fair_runnable again.

Signed-off-by: He Chen <heddchen@...cent.com>
Signed-off-by: Xiaoguang Chen <xiaoggchen@...cent.com>
---
 kernel/sched/fair.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index ae7ceba..c2f7eac 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -7004,10 +7004,9 @@ struct task_struct *
 	struct task_struct *p;
 	int new_tasks;
 
-again:
 	if (!sched_fair_runnable(rq))
 		goto idle;
-
+again:
 #ifdef CONFIG_FAIR_GROUP_SCHED
 	if (!prev || prev->sched_class != &fair_sched_class)
 		goto simple;
-- 
1.8.3.1