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SubjectRe: [PATCH] sched: remove redundant check in select_task_rq_fair
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On Tue, 2011-06-07 at 15:18 +0530, Nikunj A. Dadhania wrote:
> When balancing for wakeup affinity, a redundant check can removed.

Yes, tempting, but no, now you've got an extra call to wake_affine(),
which is more expensive.

> Signed-off-by: Nikunj A. Dadhania <nikunj@linux.vnet.ibm.com>
> ---
> kernel/sched_fair.c | 2 +-
> 1 files changed, 1 insertions(+), 1 deletions(-)
>
> diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c
> index 433491c..b9e5701 100644
> --- a/kernel/sched_fair.c
> +++ b/kernel/sched_fair.c
> @@ -1753,7 +1753,7 @@ select_task_rq_fair(struct task_struct *p, int sd_flag, int wake_flags)
> }
>
> if (affine_sd) {
> - if (cpu == prev_cpu || wake_affine(affine_sd, p, sync))
> + if (wake_affine(affine_sd, p, sync))
> prev_cpu = cpu;
>
> new_cpu = select_idle_sibling(p, prev_cpu);
>



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