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| Started by | Byungchul Park <byungchul.park@lge.com> |
|---|---|
| First post | 2017-02-16 03:40 +0100 |
| Last post | 2017-02-22 06:10 +0100 |
| Articles | 3 — 2 participants |
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[PATCH v3 1/2] sched/deadline: Remove unnecessary condition in push_dl_task() Byungchul Park <byungchul.park@lge.com> - 2017-02-16 03:40 +0100
Re: [PATCH v3 1/2] sched/deadline: Remove unnecessary condition in push_dl_task() Daniel Bristot de Oliveira <bristot@redhat.com> - 2017-02-16 18:40 +0100
Re: [PATCH v3 1/2] sched/deadline: Remove unnecessary condition in push_dl_task() Byungchul Park <byungchul.park@lge.com> - 2017-02-22 06:10 +0100
| From | Byungchul Park <byungchul.park@lge.com> |
|---|---|
| Date | 2017-02-16 03:40 +0100 |
| Subject | [PATCH v3 1/2] sched/deadline: Remove unnecessary condition in push_dl_task() |
| Message-ID | <tbk9b-8g7-9@gated-at.bofh.it> |
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.
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>
---
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
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| From | Daniel Bristot de Oliveira <bristot@redhat.com> |
|---|---|
| Date | 2017-02-16 18:40 +0100 |
| Subject | Re: [PATCH v3 1/2] sched/deadline: Remove unnecessary condition in push_dl_task() |
| Message-ID | <tbyc9-19O-5@gated-at.bofh.it> |
| In reply to | #1582281 |
On 02/16/2017 03:34 AM, 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. > > 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> +1 Reviewed-by: Daniel Bristot de Oliveira <bristot@redhat.com> -- Daniel
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| From | Byungchul Park <byungchul.park@lge.com> |
|---|---|
| Date | 2017-02-22 06:10 +0100 |
| Subject | Re: [PATCH v3 1/2] sched/deadline: Remove unnecessary condition in push_dl_task() |
| Message-ID | <tdxlD-4U0-5@gated-at.bofh.it> |
| In reply to | #1582281 |
On Thu, Feb 16, 2017 at 11:34:16AM +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.
Hello,
What do you think?
>
> 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>
> ---
> 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
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