On Tue, 16 Jun 2020 at 08:05, Peng Wang <rock...@linux.alibaba.com> wrote:
>
> While looking at enqueue_task_fair and dequeue_task_fair, it occurred
> to me that dequeue_task_fair can also be optimized as Vincent described
> in commit 7d148be69e3a ("sched/fair: Optimize enqueue_task_fair()").
>
> When encountering throttled cfs_rq, dequeue_throttle label can ensure
> se not to be NULL, and rq->nr_running remains unchanged, so we can also
> skip the early balance check.
>
> Signed-off-by: Peng Wang <rock...@linux.alibaba.com>Reviewed-by: Vincent Guittot <vincent.guit...@linaro.org> > --- > kernel/sched/fair.c | 6 +++--- > 1 file changed, 3 insertions(+), 3 deletions(-) > > diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c > index cbcb2f7..05242b7 100644 > --- a/kernel/sched/fair.c > +++ b/kernel/sched/fair.c > @@ -5614,14 +5614,14 @@ static void dequeue_task_fair(struct rq *rq, struct > task_struct *p, int flags) > > } > > -dequeue_throttle: > - if (!se) > - sub_nr_running(rq, 1); > + /* At this point se is NULL and we are at root level*/ > + sub_nr_running(rq, 1); > > /* balance early to pull high priority tasks */ > if (unlikely(!was_sched_idle && sched_idle_rq(rq))) > rq->next_balance = jiffies; > > +dequeue_throttle: > util_est_dequeue(&rq->cfs, p, task_sleep); > hrtick_update(rq); > } > -- > 2.9.5 >
