The following commit has been merged into the sched/core branch of tip:
Commit-ID: 58eeb2d79b542c678c46e245dba6b66936368a99
Gitweb: https://git.kernel.org/tip/58eeb2d79b542c678c46e245dba6b66936368a99
Author: Qais Yousef <qyousef@xxxxxxxxxxx>
AuthorDate: Sun, 24 Mar 2024 00:45:52
Committer: Ingo Molnar <mingo@xxxxxxxxxx>
CommitterDate: Mon, 25 Mar 2024 12:09:57 +01:00
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: Qais Yousef <qyousef@xxxxxxxxxxx>
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
Reviewed-by: Vincent Guittot <vincent.guittot@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20240324004552.999936-5-qyousef@xxxxxxxxxxx
---
kernel/sched/fair.c | 13 +++++++++++--
1 file changed, 11 insertions(+), 2 deletions(-)
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index c47c4f2..dbf4f1c 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -11449,8 +11449,12 @@ more_balance:
* 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 @@ out_one_pinned:
* 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 */
|