linux-kernel - [RFC PATCH v2 24/25] sched/core: Execute enqueued balance callbacks when changing allowed CPUs

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Message-ID: <20250731105543.40832-25-yurand2000@gmail.com>
Date: Thu, 31 Jul 2025 12:55:42 +0200
From: Yuri Andriaccio <yurand2000@...il.com>
To: Ingo Molnar <mingo@...hat.com>,
	Peter Zijlstra <peterz@...radead.org>,
	Juri Lelli <juri.lelli@...hat.com>,
	Vincent Guittot <vincent.guittot@...aro.org>,
	Dietmar Eggemann <dietmar.eggemann@....com>,
	Steven Rostedt <rostedt@...dmis.org>,
	Ben Segall <bsegall@...gle.com>,
	Mel Gorman <mgorman@...e.de>,
	Valentin Schneider <vschneid@...hat.com>
Cc: linux-kernel@...r.kernel.org,
	Luca Abeni <luca.abeni@...tannapisa.it>,
	Yuri Andriaccio <yuri.andriaccio@...tannapisa.it>
Subject: [RFC PATCH v2 24/25] sched/core: Execute enqueued balance callbacks when changing allowed CPUs

From: luca abeni <luca.abeni@...tannapisa.it>

Execute balancing callbacks when setting the affinity of a task, since the HCBS
scheduler may request balancing of throttled dl_servers to fully utilize the
server's bandwidth.

Signed-off-by: luca abeni <luca.abeni@...tannapisa.it>
Signed-off-by: Yuri Andriaccio <yurand2000@...il.com>
---
 kernel/sched/core.c | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index eb9de8c7b1f..c8763c46030 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -2947,6 +2947,7 @@ static int affine_move_task(struct rq *rq, struct task_struct *p, struct rq_flag
 	if (cpumask_test_cpu(task_cpu(p), &p->cpus_mask) ||
 	    (task_current_donor(rq, p) && !task_current(rq, p))) {
 		struct task_struct *push_task = NULL;
+		struct balance_callback *head;
 
 		if ((flags & SCA_MIGRATE_ENABLE) &&
 		    (p->migration_flags & MDF_PUSH) && !rq->push_busy) {
@@ -2965,11 +2966,13 @@ static int affine_move_task(struct rq *rq, struct task_struct *p, struct rq_flag
 		}
 
 		preempt_disable();
+		head = splice_balance_callbacks(rq);
 		task_rq_unlock(rq, p, rf);
 		if (push_task) {
 			stop_one_cpu_nowait(rq->cpu, push_cpu_stop,
 					    p, &rq->push_work);
 		}
+		balance_callbacks(rq, head);
 		preempt_enable();
 
 		if (complete)
@@ -3024,6 +3027,8 @@ static int affine_move_task(struct rq *rq, struct task_struct *p, struct rq_flag
 	}
 
 	if (task_on_cpu(rq, p) || READ_ONCE(p->__state) == TASK_WAKING) {
+		struct balance_callback *head;
+
 		/*
 		 * MIGRATE_ENABLE gets here because 'p == current', but for
 		 * anything else we cannot do is_migration_disabled(), punt
@@ -3037,16 +3042,19 @@ static int affine_move_task(struct rq *rq, struct task_struct *p, struct rq_flag
 			p->migration_flags &= ~MDF_PUSH;
 
 		preempt_disable();
+		head = splice_balance_callbacks(rq);
 		task_rq_unlock(rq, p, rf);
 		if (!stop_pending) {
 			stop_one_cpu_nowait(cpu_of(rq), migration_cpu_stop,
 					    &pending->arg, &pending->stop_work);
 		}
+		balance_callbacks(rq, head);
 		preempt_enable();
 
 		if (flags & SCA_MIGRATE_ENABLE)
 			return 0;
 	} else {
+		struct balance_callback *head;
 
 		if (!is_migration_disabled(p)) {
 			if (task_on_rq_queued(p))
@@ -3057,7 +3065,12 @@ static int affine_move_task(struct rq *rq, struct task_struct *p, struct rq_flag
 				complete = true;
 			}
 		}
+
+		preempt_disable();
+		head = splice_balance_callbacks(rq);
 		task_rq_unlock(rq, p, rf);
+		balance_callbacks(rq, head);
+		preempt_enable();
 
 		if (complete)
 			complete_all(&pending->done);
-- 
2.50.1