[PATCH RFC] sched/fair: simplfy the work when reweighting entity

From: Jiang Biao
Date: Tue Aug 04 2020 - 03:12:36 EST


If a se is on_rq when reweighting entity, all we need should be
updating the load of cfs_rq, other dequeue/enqueue works could be
redundant, such as,
* account_numa_dequeue/account_numa_enqueue
* list_del/list_add from/into cfs_tasks
* nr_running--/nr_running++

Just simplfy the work. Could be helpful for the hot path.

Signed-off-by: Jiang Biao <benbjiang@xxxxxxxxxxx>
---
kernel/sched/fair.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 04fa8dbcfa4d..18a8fc7bd0de 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -3086,7 +3086,7 @@ static void reweight_entity(struct cfs_rq *cfs_rq, struct sched_entity *se,
/* commit outstanding execution time */
if (cfs_rq->curr == se)
update_curr(cfs_rq);
- account_entity_dequeue(cfs_rq, se);
+ update_load_sub(&cfs_rq->load, se->load.weight);
}
dequeue_load_avg(cfs_rq, se);

@@ -3102,7 +3102,7 @@ static void reweight_entity(struct cfs_rq *cfs_rq, struct sched_entity *se,

enqueue_load_avg(cfs_rq, se);
if (se->on_rq)
- account_entity_enqueue(cfs_rq, se);
+ update_load_add(&cfs_rq->load, se->load.weight);

}

--
2.21.0