Messages in this thread | | | From | Namhyung Kim <> | Subject | Re: [PATCH] sched: Get rid of unnecessary checks from select_idle_sibling | Date | Wed, 09 Jan 2013 16:54:09 +0900 |
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Hi Alex,
On Wed, 09 Jan 2013 15:33:40 +0800, Alex Shi wrote: > On 01/09/2013 02:50 PM, Namhyung Kim wrote: >> From: Namhyung Kim <namhyung.kim@lge.com> >> >> AFAICS @target cpu of select_idle_sibling() is always either prev_cpu >> or this_cpu. So no need to check it again and the conditionals can be >> consolidated. [snip] > Uh, we don't know if the target is this_cpu or previous cpu, If we just > check the target idle status, we may miss another idle cpu. So this > patch change the logical in this function.
select_idle_sibling() is called only in select_task_rq_fair() if it found a suitable affine_sd. The default target is the 'prev_cpu' of the task but if wake_affine() returns true it'd be (this) 'cpu'.
I cannot see where the prev_cpu or the cpu is set to another one before calling select_idle_sibling.
Thanks, Namhyung
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