linux-kernel - [PATCH v4 2/2] sched/rt: Trying to push current task when target disable migrating

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Message-Id: <20220708211755.73637-2-schspa@gmail.com>
Date:   Sat,  9 Jul 2022 05:17:55 +0800
From:   Schspa Shi <schspa@...il.com>
To:     mingo@...hat.com, peterz@...radead.org, juri.lelli@...hat.com,
        vincent.guittot@...aro.org, dietmar.eggemann@....com,
        rostedt@...dmis.org, bsegall@...gle.com, mgorman@...e.de,
        bristot@...hat.com, vschneid@...hat.com
Cc:     linux-kernel@...r.kernel.org, zhaohui.shi@...izon.ai,
        Schspa Shi <schspa@...il.com>
Subject: [PATCH v4 2/2] sched/rt: Trying to push current task when target disable migrating

When the task to push disable migration, retry to push the current
running task on this CPU away, instead doing nothing for this migrate
disabled task.

Signed-off-by: Schspa Shi <schspa@...il.com>
---
 kernel/sched/core.c | 6 +++++-
 kernel/sched/rt.c   | 6 ++++++
 2 files changed, 11 insertions(+), 1 deletion(-)

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index da0bf6fe9ecdc..0b1fefd97d874 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -2509,8 +2509,12 @@ int push_cpu_stop(void *arg)
 	if (p->sched_class->find_lock_rq)
 		lowest_rq = p->sched_class->find_lock_rq(p, rq);
 
-	if (!lowest_rq)
+	if (!lowest_rq) {
+		if (unlikely(is_migration_disabled(p)))
+			p->migration_flags |= MDF_PUSH;
+
 		goto out_unlock;
+	}
 
 	// XXX validate p is still the highest prio task
 	if (task_rq(p) == rq) {
diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c
index 0e0bc9aeaa394..9a91adf486e34 100644
--- a/kernel/sched/rt.c
+++ b/kernel/sched/rt.c
@@ -2135,6 +2135,12 @@ static int push_rt_task(struct rq *rq, bool pull)
 		 */
 		task = pick_next_pushable_task(rq);
 		if (task == next_task) {
+			/*
+			 * If next task has now disabled migrating, see if we
+			 * can push the current task.
+			 */
+			if (unlikely(is_migration_disabled(task)))
+				goto retry;
 			/*
 			 * The task hasn't migrated, and is still the next
 			 * eligible task, but we failed to find a run-queue
-- 
2.37.0