[PATCH] sched: Optimize core cookie matching check

[Fernand Sieber]

Early return true if the core cookie matches. This avoids the SMT mask
loop to check for an idle core, which might be more expensive on wide
platforms.

Signed-off-by: Fernand Sieber <sieberf@xxxxxxxxxx>
---
 kernel/sched/sched.h | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index adfb6e3409d7..381cd561e99b 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -1432,6 +1432,9 @@ static inline bool sched_core_cookie_match(struct rq *rq, struct task_struct *p)
 	if (!sched_core_enabled(rq))
 		return true;
 
+	if (rq->core->core_cookie == p->core_cookie)
+		return true;
+
 	for_each_cpu(cpu, cpu_smt_mask(cpu_of(rq))) {
 		if (!available_idle_cpu(cpu)) {
 			idle_core = false;
@@ -1443,7 +1446,7 @@ static inline bool sched_core_cookie_match(struct rq *rq, struct task_struct *p)
 	 * A CPU in an idle core is always the best choice for tasks with
 	 * cookies.
 	 */
-	return idle_core || rq->core->core_cookie == p->core_cookie;
+	return idle_core;
 }
 
 static inline bool sched_group_cookie_match(struct rq *rq,
-- 
2.43.0




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