linux-kernel - [PATCH 2/2] sched/preempt: Avoid updating for duplicate preempt mode

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Message-Id: <20240112091916.696185-2-songshuaishuai@tinylab.org>
Date: Fri, 12 Jan 2024 17:19:16 +0800
From: Song Shuai <songshuaishuai@...ylab.org>
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,
	bristot@...hat.com,
	vschneid@...hat.com
Cc: linux-kernel@...r.kernel.org,
	Song Shuai <songshuaishuai@...ylab.org>
Subject: [PATCH 2/2] sched/preempt: Avoid updating for duplicate preempt mode

When echoing the current preempt mode to /sys/kernel/debug/sched/preempt,
we don't have to update SC or SK in the sched_dynamic_update() function.

Stop it at the sched_dynamic_write() function.

Signed-off-by: Song Shuai <songshuaishuai@...ylab.org>
---
 kernel/sched/debug.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/kernel/sched/debug.c b/kernel/sched/debug.c
index 4580a450700e..dafcfdfae23d 100644
--- a/kernel/sched/debug.c
+++ b/kernel/sched/debug.c
@@ -235,7 +235,8 @@ static ssize_t sched_dynamic_write(struct file *filp, const char __user *ubuf,
 	if (mode < 0)
 		return mode;
 
-	sched_dynamic_update(mode);
+	if (preempt_dynamic_mode != mode)
+		sched_dynamic_update(mode);
 
 	*ppos += cnt;
 
-- 
2.39.2