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@infradead.org>
Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Acked-by: Mel Gorman <mgorman@suse.de>
Link: https://lore.kernel.org/r/20211019123537.17146-5-vincent.guittot@linaro.org

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index e50fd751e1dfa0c55f218d2dc779d10e4813786c..57eae0ebc492e80a86ea21dddd85e84cec576d62 100644 (file)
--- 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)