Re: [PATCH] sched/rt: Remove redundant nr_cpus_allowed test

From: Steven Rostedt
Date: Fri Oct 04 2013 - 15:34:10 EST


On Fri, 4 Oct 2013 14:24:53 -0500
Shawn Bohrer <shawn.bohrer@xxxxxxxxx> wrote:

> From: Shawn Bohrer <sbohrer@xxxxxxxxxxxxxxx>
>
> In 76854c7e8f3f4172fef091e78d88b3b751463ac6 "sched: Use
> rt.nr_cpus_allowed to recover select_task_rq() cycles" an optimization
> was added to select_task_rq_rt() that immediately returns when
> p->nr_cpus_allowed == 1 at the beginning of the function. This makes
> the latter p->nr_cpus_allowed > 1 check redundant and can be removed.
>
> Signed-off-by: Shawn Bohrer <sbohrer@xxxxxxxxxxxxxxx>

Reviewed-by: Steven Rostedt <rostedt@xxxxxxxxxxx>

-- Steve

> ---
> kernel/sched/rt.c | 3 +--
> 1 file changed, 1 insertion(+), 2 deletions(-)
>
> diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c
> index 01970c8..ceebfba 100644
> --- a/kernel/sched/rt.c
> +++ b/kernel/sched/rt.c
> @@ -1213,8 +1213,7 @@ select_task_rq_rt(struct task_struct *p, int sd_flag, int flags)
> */
> if (curr && unlikely(rt_task(curr)) &&
> (curr->nr_cpus_allowed < 2 ||
> - curr->prio <= p->prio) &&
> - (p->nr_cpus_allowed > 1)) {
> + curr->prio <= p->prio)) {
> int target = find_lowest_rq(p);
>
> if (target != -1)

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