lkml.org 
[lkml]   [2017]   [May]   [17]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [RESEND PATCH v3] sched/deadline: Remove unnecessary condition in push_dl_task()
On Fri, May 12, 2017 at 10:05:59AM +0900, Byungchul Park wrote:
> pick_next_pushable_dl_task(rq) has BUG_ON(rq->cpu != task_cpu(task))
> when it returns a task other than NULL, which means that task_cpu(task)
> must be rq->cpu. So if task == next_task, then task_cpu(next_task) must
> be rq->cpu as well. Remove the redundant condition and make code simpler.
>
> By this patch, unnecessary one branch and two LOAD operations in 'if'
> statement can be avoided.

+cc rostedt@goodmis.org
+cc juri.lelli@arm.com
+cc bristot@redhat.com

>
> Signed-off-by: Byungchul Park <byungchul.park@lge.com>
> Reviewed-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
> Reviewed-by: Juri Lelli <juri.lelli@arm.com>
> Reviewed-by: Daniel Bristot de Oliveira <bristot@redhat.com>
> ---
> 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) {
> /*
> * The task is still there. We don't try
> * again, some other cpu will pull it when ready.
> --
> 1.9.1

\
 
 \ /
  Last update: 2017-05-18 04:00    [W:0.043 / U:0.124 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site