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From:   ultrachin@163.com
To:     linux-kernel@vger.kernel.org
Cc:     mingo@redhat.com, peterz@infradead.org, juri.lelli@redhat.com,
        vincent.guittot@linaro.org, dietmar.eggemann@arm.com,
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        bristot@redhat.com, heddchen@tencent.com, xiaoggchen@tencent.com
Subject: [PATCH] sched: pull tasks when CPU is about to run SCHED_IDLE tasks
Date:   Wed, 23 Dec 2020 16:09:28 +0800
Message-Id: <1608710968-31475-1-git-send-email-ultrachin@163.com>
Precedence: bulk

From: Chen Xiaoguang <xiaoggchen@tencent.com>

Before a CPU switches from running SCHED_NORMAL task to
SCHED_IDLE task, trying to pull SCHED_NORMAL tasks from other
CPU by doing load_balance first.

Signed-off-by: Chen Xiaoguang <xiaoggchen@tencent.com>
Signed-off-by: Chen He <heddchen@tencent.com>
---
 kernel/sched/fair.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index ae7ceba..0a26132 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -7004,6 +7004,11 @@ struct task_struct *
 	struct task_struct *p;
 	int new_tasks;
 
+	if (prev &&
+	    fair_policy(prev->policy) &&
+	    sched_idle_cpu(rq->cpu))
+		goto idle;
+
 again:
 	if (!sched_fair_runnable(rq))
 		goto idle;
-- 
1.8.3.1