Commit 58eeb2d7 authored by Qais Yousef's avatar Qais Yousef Committed by Ingo Molnar
Browse files

sched/fair: Don't double balance_interval for migrate_misfit 



It is not necessarily an indication of the system being busy and
requires a backoff of the load balancer activities. But pushing it high
could mean generally delaying other misfit activities or other type of
imbalances.

Also don't pollute nr_balance_failed because of misfit failures. The
value is used for enabling cache hot migration and in migrate_util/load
types. None of which should be impacted (skewed) by misfit failures.

Signed-off-by: default avatarQais Yousef <qyousef@layalina.io>
Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
Reviewed-by: default avatarVincent Guittot <vincent.guittot@linaro.org>
Link: https://lore.kernel.org/r/20240324004552.999936-5-qyousef@layalina.io
parent fa427e8e

kernel/sched/fair.c

+11 −2
Original line number Diff line number Diff line
@@ -11449,8 +11449,12 @@ static int sched_balance_rq(int this_cpu, struct rq *this_rq, 
		 * We do not want newidle balance, which can be very

		 * frequent, pollute the failure counter causing

		 * excessive cache_hot migrations and active balances.

		 *

		 * Similarly for migration_misfit which is not related to

		 * load/util migration, don't pollute nr_balance_failed.

		 */

		if (idle != CPU_NEWLY_IDLE)

		if (idle != CPU_NEWLY_IDLE &&

		    env.migration_type != migrate_misfit)

			sd->nr_balance_failed++;



		if (need_active_balance(&env)) {
@@ -11533,8 +11537,13 @@ static int sched_balance_rq(int this_cpu, struct rq *this_rq, 
	 * repeatedly reach this code, which would lead to balance_interval

	 * skyrocketing in a short amount of time. Skip the balance_interval

	 * increase logic to avoid that.

	 *

	 * Similarly misfit migration which is not necessarily an indication of

	 * the system being busy and requires lb to backoff to let it settle

	 * down.

	 */

	if (env.idle == CPU_NEWLY_IDLE)

	if (env.idle == CPU_NEWLY_IDLE ||

	    env.migration_type == migrate_misfit)

		goto out;



	/* tune up the balancing interval */