sched/core: Optimize core cookie matching check

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@amazon.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: K Prateek Nayak <kprateek.nayak@amd.com>
Reviewed-by: Madadi Vineeth Reddy <vineethr@linux.ibm.com>
Link: https://patch.msgid.link/20251105152538.470586-1-sieberf@amazon.com

diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index d04e007608a324b1470b7cec330f498e7acc599f..82e74e8ca2eacdca20ad99d581c8557920003d1a 100644 (file)
--- 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,