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authorVincent Guittot2021-10-19 14:35:34 +0200
committerPeter Zijlstra2021-10-31 11:11:37 +0100
commit9d783c8dd112ad4b619e74e4bf57d2be0b400693 (patch)
treecf68010c9b8ecc7df550466273d627d67c830401 /kernel
parent9e9af819db5dbe4bf99101628955a26e2a41a1a5 (diff)
sched/fair: Skip update_blocked_averages if we are defering load balance
In newidle_balance(), the scheduler skips load balance to the new idle cpu when the 1st sd of this_rq is: this_rq->avg_idle < sd->max_newidle_lb_cost Doing a costly call to update_blocked_averages() will not be useful and simply adds overhead when this condition is true. Check the condition early in newidle_balance() to skip update_blocked_averages() when possible. Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org> Signed-off-by: Tim Chen <tim.c.chen@linux.intel.com> 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/20211019123537.17146-3-vincent.guittot@linaro.org
Diffstat (limited to 'kernel')
-rw-r--r--kernel/sched/fair.c9
1 files changed, 6 insertions, 3 deletions
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index c0145677ee99..c4c36865321b 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -10873,17 +10873,20 @@ static int newidle_balance(struct rq *this_rq, struct rq_flags *rf)
*/
rq_unpin_lock(this_rq, 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)) {
+ !READ_ONCE(this_rq->rd->overload) ||
+ (sd && this_rq->avg_idle < sd->max_newidle_lb_cost)) {
- rcu_read_lock();
- sd = rcu_dereference_check_sched_domain(this_rq->sd);
if (sd)
update_next_balance(sd, &next_balance);
rcu_read_unlock();
goto out;
}
+ rcu_read_unlock();
raw_spin_rq_unlock(this_rq);