linux-kernel - [PATCH v2 06/12] sched: Introduce ttwu_do

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Message-ID: <20250702121158.932926181@infradead.org>
Date: Wed, 02 Jul 2025 13:49:30 +0200
From: Peter Zijlstra <peterz@...radead.org>
To: mingo@...hat.com,
 juri.lelli@...hat.com,
 vincent.guittot@...aro.org,
 dietmar.eggemann@....com,
 rostedt@...dmis.org,
 bsegall@...gle.com,
 mgorman@...e.de,
 vschneid@...hat.com,
 clm@...a.com
Cc: linux-kernel@...r.kernel.org,
 peterz@...radead.org
Subject: [PATCH v2 06/12] sched: Introduce ttwu_do_migrate()

Split out the migration related bits into their own function for later
re-use.

Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
---
 kernel/sched/core.c |   26 ++++++++++++++++----------
 1 file changed, 16 insertions(+), 10 deletions(-)

--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -3774,6 +3774,21 @@ static int ttwu_runnable(struct task_str
 	return 1;
 }
 
+static inline bool ttwu_do_migrate(struct task_struct *p, int cpu)
+{
+	if (task_cpu(p) == cpu)
+		return false;
+
+	if (p->in_iowait) {
+		delayacct_blkio_end(p);
+		atomic_dec(&task_rq(p)->nr_iowait);
+	}
+
+	psi_ttwu_dequeue(p);
+	set_task_cpu(p, cpu);
+	return true;
+}
+
 void sched_ttwu_pending(void *arg)
 {
 	struct llist_node *llist = arg;
@@ -4268,17 +4283,8 @@ int try_to_wake_up(struct task_struct *p
 		 * their previous state and preserve Program Order.
 		 */
 		smp_cond_load_acquire(&p->on_cpu, !VAL);
-
-		if (task_cpu(p) != cpu) {
-			if (p->in_iowait) {
-				delayacct_blkio_end(p);
-				atomic_dec(&task_rq(p)->nr_iowait);
-			}
-
+		if (ttwu_do_migrate(p, cpu))
 			wake_flags |= WF_MIGRATED;
-			psi_ttwu_dequeue(p);
-			set_task_cpu(p, cpu);
-		}
 
 		ttwu_queue(p, cpu, wake_flags);
 	}