linux-kernel - [PATCH v2 14/15] sched/deadline: Do not restart the DL server on replenish from timer

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Date: Tue, 12 Mar 2024 21:24:50 -0400
From: "Joel Fernandes (Google)" <joel@...lfernandes.org>
To: linux-kernel@...r.kernel.org,
	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>,
	Daniel Bristot de Oliveira <bristot@...hat.com>,
	Valentin Schneider <vschneid@...hat.com>
Cc: Suleiman Souhlal <suleiman@...gle.com>,
	Youssef Esmat <youssefesmat@...gle.com>,
	David Vernet <void@...ifault.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	"Paul E . McKenney" <paulmck@...nel.org>,
	joseph.salisbury@...onical.com,
	Luca Abeni <luca.abeni@...tannapisa.it>,
	Tommaso Cucinotta <tommaso.cucinotta@...tannapisa.it>,
	Vineeth Pillai <vineeth@...byteword.org>,
	Shuah Khan <skhan@...uxfoundation.org>,
	Phil Auld <pauld@...hat.com>,
	"Joel Fernandes (Google)" <joel@...lfernandes.org>
Subject: [PATCH v2 14/15] sched/deadline: Do not restart the DL server on replenish from timer

There is no point in doing so if there are no CFS tasks to run. If there
were, we would be doing ENQUEUE_REPLENISH from the dl_task_timer,
instead of calling replenish_dl_entity(). Fix that.

Signed-off-by: Joel Fernandes (Google) <joel@...lfernandes.org>
---
 kernel/sched/deadline.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c
index e978e299381c..179369d27f66 100644
--- a/kernel/sched/deadline.c
+++ b/kernel/sched/deadline.c
@@ -915,7 +915,7 @@ static void replenish_dl_entity(struct sched_dl_entity *dl_se)
 	 */
 	if (dl_se->dl_defer &&
 	    dl_time_before(rq_clock(rq), dl_se->deadline - dl_se->runtime)) {
-		if (!is_dl_boosted(dl_se)) {
+		if (!is_dl_boosted(dl_se) && dl_se->server_has_tasks(dl_se)) {
 			dl_se->dl_defer_armed = 1;
 			dl_se->dl_throttled = 1;
 			if (!start_dl_timer(dl_se)) {
-- 
2.34.1