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From:   Vincent Guittot <vincent.guittot@linaro.org>
To:     mingo@redhat.com, peterz@infradead.org, juri.lelli@redhat.com,
        dietmar.eggemann@arm.com, rostedt@goodmis.org, bsegall@google.com,
        mgorman@suse.de, bristot@redhat.com, linux-kernel@vger.kernel.org,
        tim.c.chen@linux.intel.com
Cc:     Vincent Guittot <vincent.guittot@linaro.org>
Subject: [PATCH v3 4/5] sched/fair: Remove sysctl_sched_migration_cost condition
Date:   Tue, 19 Oct 2021 14:35:36 +0200
Message-Id: <20211019123537.17146-5-vincent.guittot@linaro.org>
In-Reply-To: <20211019123537.17146-1-vincent.guittot@linaro.org>
References: <20211019123537.17146-1-vincent.guittot@linaro.org>
Precedence: bulk

With a default value of 500us, sysctl_sched_migration_cost is
significanlty higher than the cost of load_balance. Remove the
condition and rely on the sd->max_newidle_lb_cost to abort
newidle_balance.

Suggested-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
---
 kernel/sched/fair.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index e50fd751e1df..57eae0ebc492 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -10895,8 +10895,7 @@ static int newidle_balance(struct rq *this_rq, struct rq_flags *rf)
 	rcu_read_lock();
 	sd = rcu_dereference_check_sched_domain(this_rq->sd);
 
-	if (this_rq->avg_idle < sysctl_sched_migration_cost ||
-	    !READ_ONCE(this_rq->rd->overload) ||
+	if (!READ_ONCE(this_rq->rd->overload) ||
 	    (sd && this_rq->avg_idle < sd->max_newidle_lb_cost)) {
 
 		if (sd)
-- 
2.17.1