linux-kernel - [RFC PATCH 2/5] sched/core: Don't use parked cpu for selection

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Message-ID: <20250523181448.3777233-3-sshegde@linux.ibm.com>
Date: Fri, 23 May 2025 23:44:45 +0530
From: Shrikanth Hegde <sshegde@...ux.ibm.com>
To: mingo@...hat.com, peterz@...radead.org, juri.lelli@...hat.com,
        vincent.guittot@...aro.org, tglx@...utronix.de, yury.norov@...il.com,
        maddy@...ux.ibm.com
Cc: sshegde@...ux.ibm.com, vschneid@...hat.com, dietmar.eggemann@....com,
        rostedt@...dmis.org, jstultz@...gle.com, kprateek.nayak@....com,
        huschle@...ux.ibm.com, srikar@...ux.ibm.com,
        linux-kernel@...r.kernel.org, linux@...musvillemoes.dk
Subject: [RFC PATCH 2/5] sched/core: Don't use parked cpu for selection

When the current running task is pushed using stop class mechanism, the
new CPU that going to be chosen shouldn't be a parked CPU. 

Signed-off-by: Shrikanth Hegde <sshegde@...ux.ibm.com>
---
 kernel/sched/core.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 62b3416f5e43..9ec12f9b3b08 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -3526,7 +3526,7 @@ static int select_fallback_rq(int cpu, struct task_struct *p)
 		nodemask = cpumask_of_node(nid);
 
 		/* Look for allowed, online CPU in same node. */
-		for_each_cpu(dest_cpu, nodemask) {
+		for_each_cpu_andnot(dest_cpu, nodemask, cpu_parked_mask) {
 			if (is_cpu_allowed(p, dest_cpu))
 				return dest_cpu;
 		}
@@ -3534,7 +3534,7 @@ static int select_fallback_rq(int cpu, struct task_struct *p)
 
 	for (;;) {
 		/* Any allowed, online CPU? */
-		for_each_cpu(dest_cpu, p->cpus_ptr) {
+		for_each_cpu_andnot(dest_cpu, p->cpus_ptr, cpu_parked_mask) {
 			if (!is_cpu_allowed(p, dest_cpu))
 				continue;
 
-- 
2.39.3