Re: [PATCH] sched/deadline: Remove unnecessary condition in push_dl_task()

From: Juri Lelli
Date: Wed Feb 15 2017 - 05:48:01 EST


[+Steve, Luca]

Hi,

On 15/02/17 14:11, Byungchul Park wrote:
> Once pick_next_pushable_dl_task(rq) return a task, it guarantees that
> the task's cpu is rq->cpu, so task_cpu(next_task) is always rq->cpu if
> task == next_task. Remove a redundant condition and make code simpler.
>
> Signed-off-by: Byungchul Park <byungchul.park@xxxxxxx>
> ---
> kernel/sched/deadline.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c
> index 27737f3..ad8d577 100644
> --- a/kernel/sched/deadline.c
> +++ b/kernel/sched/deadline.c
> @@ -1483,7 +1483,7 @@ static int push_dl_task(struct rq *rq)
> * then possible that next_task has migrated.
> */
> task = pick_next_pushable_dl_task(rq);
> - if (task_cpu(next_task) == rq->cpu && task == next_task) {
> + if (task == next_task) {

Seems a sensible optimization to me. Actually, we are doing the same for
rt.c; Steve, Peter, do you think we should optimize that as well?

Thanks,

- Juri