[tip: sched/core] sched/fair: Simplify the work when reweighting entity

tip-bot2 for Jiang Biao
2020-08-27T07:55:43Z

The following commit has been merged into the sched/core branch of tip:

Commit-ID: 1724b95b92979a8ea8e55a4817d05b3bb7750958
Gitweb: https://git.kernel.org/tip/1724b95b92979a8ea8e55a4817d05b3bb7750958
Author: Jiang Biao <benbjiang@tencent.com>
AuthorDate: Tue, 11 Aug 2020 19:32:09 +08:00
Committer: Peter Zijlstra <peterz@infradead.org>
CommitterDate: Wed, 26 Aug 2020 12:41:58 +02:00

sched/fair: Simplify the work when reweighting entity

The code in reweight_entity() can be simplified.

For a sched entity on the rq, the entity accounting can be replaced by
cfs_rq instantaneous load updates currently called from within the
entity accounting.

Even though an entity on the rq can't represent a task in
reweight_entity() (a task is always dequeued before calling this
function) and so the numa task accounting and the rq->cfs_tasks list
management of the entity accounting are never called, the redundant
cfs_rq->nr_running decrement/increment will be avoided.

Signed-off-by: Jiang Biao <benbjiang@tencent.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org>
Link: https://lkml.kernel.org/r/20200811113209.34057-1-benbjiang@tencent.com
---
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 90ebaa4..33699db 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -3084,7 +3084,7 @@ 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);

@@ -3100,7 +3100,7 @@ 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);

}