linux-kernel - [PATCH V1] sched: Cancel the slice protection of the idle entity

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Message-Id: <20250121030628.113497-1-15645113830zzh@gmail.com>
Date: Tue, 21 Jan 2025 11:06:29 +0800
From: zihan zhou <15645113830zzh@...il.com>
To: 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,
	vschneid@...hat.com
Cc: linux-kernel@...r.kernel.org,
	zihan zhou <15645113830zzh@...il.com>
Subject: [PATCH V1] sched: Cancel the slice protection of the idle entity

A wakeup non-idle entity should preempt idle entity at any time,
but because of the slice protection of the idle entity, the non-idle
entity has to wait, so just cancel it.

Signed-off-by: zihan zhou <15645113830zzh@...il.com>
---
 kernel/sched/fair.c | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 3e9ca38512de..7777d110d053 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -8851,8 +8851,19 @@ static void check_preempt_wakeup_fair(struct rq *rq, struct task_struct *p, int
 	 * Preempt an idle entity in favor of a non-idle entity (and don't preempt
 	 * in the inverse case).
 	 */
-	if (cse_is_idle && !pse_is_idle)
+	if (cse_is_idle && !pse_is_idle) {
+
+		/*
+		 * When non-idle entity preempt an idle entity,
+		 * don't give idle entity slice protection.
+		 */
+		if (se->vlag == se->deadline)
+			se->vlag = se->deadline + 1;
+
 		goto preempt;
+
+	}
+
 	if (cse_is_idle != pse_is_idle)
 		return;
 
-- 
2.33.0