linux-kernel - [PATCH] sched/deadline: Add DL server activated message

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Message-ID: <20250805155347.1693676-1-kuyo.chang@mediatek.com>
Date: Tue, 5 Aug 2025 23:53:32 +0800
From: Kuyo Chang <kuyo.chang@...iatek.com>
To: Ingo Molnar <mingo@...hat.com>, Peter Zijlstra <peterz@...radead.org>,
	Juri Lelli <juri.lelli@...hat.com>, Vincent Guittot
	<vincent.guittot@...aro.org>, Dietmar Eggemann <dietmar.eggemann@....com>,
	Steven Rostedt <rostedt@...dmis.org>, Ben Segall <bsegall@...gle.com>, "Mel
 Gorman" <mgorman@...e.de>, Valentin Schneider <vschneid@...hat.com>,
	"Matthias Brugger" <matthias.bgg@...il.com>, AngeloGioacchino Del Regno
	<angelogioacchino.delregno@...labora.com>
CC: kuyo chang <kuyo.chang@...iatek.com>, <linux-kernel@...r.kernel.org>,
	<linux-arm-kernel@...ts.infradead.org>, <linux-mediatek@...ts.infradead.org>
Subject: [PATCH] sched/deadline: Add DL server activated message

From: kuyo chang <kuyo.chang@...iatek.com>

The DL server is introduced as a replacement for realtime throttling.
When RT throttling is activated, a message
"sched: RT throttling activated" is shown. However, it is currently
difficult for users to know when the DL server is activated.

This patch adds a similar message to indicate when the DL server
is activated, which helps users debug RT/CFS contention issues.

Signed-off-by: kuyo chang <kuyo.chang@...iatek.com>
---
 kernel/sched/deadline.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c
index e2d51f4306b3..8e0de6cdb980 100644
--- a/kernel/sched/deadline.c
+++ b/kernel/sched/deadline.c
@@ -2042,6 +2042,9 @@ enqueue_dl_entity(struct sched_dl_entity *dl_se, int flags)
 	}
 
 	__enqueue_dl_entity(dl_se);
+
+	if (dl_server(dl_se))
+		printk_deferred_once("sched: dl_server activated\n");
 }
 
 static void dequeue_dl_entity(struct sched_dl_entity *dl_se, int flags)
-- 
2.45.2