linux-kernel - [tip: sched/core] sched/fair: Remove sysctl_sched_migration

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Date:   Sun, 31 Oct 2021 10:16:24 -0000
From:   "tip-bot2 for Vincent Guittot" <tip-bot2@...utronix.de>
To:     linux-tip-commits@...r.kernel.org
Cc:     "Peter Zijlstra (Intel)" <peterz@...radead.org>,
        Vincent Guittot <vincent.guittot@...aro.org>,
        Dietmar Eggemann <dietmar.eggemann@....com>,
        Mel Gorman <mgorman@...e.de>, x86@...nel.org,
        linux-kernel@...r.kernel.org
Subject: [tip: sched/core] sched/fair: Remove sysctl_sched_migration_cost condition

The following commit has been merged into the sched/core branch of tip:

Commit-ID:     c5b0a7eefc70150caf23e37bc9d639c68c87a097
Gitweb:        https://git.kernel.org/tip/c5b0a7eefc70150caf23e37bc9d639c68c87a097
Author:        Vincent Guittot <vincent.guittot@...aro.org>
AuthorDate:    Tue, 19 Oct 2021 14:35:36 +02:00
Committer:     Peter Zijlstra <peterz@...radead.org>
CommitterDate: Sun, 31 Oct 2021 11:11:38 +01:00

sched/fair: Remove sysctl_sched_migration_cost condition

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@...radead.org>
Signed-off-by: Vincent Guittot <vincent.guittot@...aro.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Reviewed-by: Dietmar Eggemann <dietmar.eggemann@....com>
Acked-by: Mel Gorman <mgorman@...e.de>
Link: https://lore.kernel.org/r/20211019123537.17146-5-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 e50fd75..57eae0e 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)