linux-kernel - [PATCH 2/6] sched_ext: Add scx_enabled() test to @start_class promotion in put_prev_task

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20240804024047.100355-3-tj@kernel.org>
Date: Sat,  3 Aug 2024 16:40:09 -1000
From: Tejun Heo <tj@...nel.org>
To: void@...ifault.com,
	peterz@...radead.org
Cc: linux-kernel@...r.kernel.org,
	kernel-team@...a.com,
	mingo@...hat.com,
	Tejun Heo <tj@...nel.org>
Subject: [PATCH 2/6] sched_ext: Add scx_enabled() test to @start_class promotion in put_prev_task_balance()

SCX needs its balance() invoked even when waking up from a lower priority
sched class (idle) and put_prev_task_balance() thus has the logic to promote
@start_class if it's lower than ext_sched_class. This is only needed when
SCX is enabled. Add scx_enabled() test to avoid unnecessary overhead when
SCX is disabled.

Signed-off-by: Tejun Heo <tj@...nel.org>
Suggested-by: Peter Zijlstra <peterz@...radead.org>
---
 kernel/sched/core.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 7994118eee53..0532b27fd9af 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -5836,7 +5836,7 @@ static void put_prev_task_balance(struct rq *rq, struct task_struct *prev,
 	 * when waking up from SCHED_IDLE. If @start_class is below SCX, start
 	 * from SCX instead.
 	 */
-	if (sched_class_above(&ext_sched_class, start_class))
+	if (scx_enabled() && sched_class_above(&ext_sched_class, start_class))
 		start_class = &ext_sched_class;
 #endif
 
-- 
2.46.0