On 01/09/2013 03:54 PM, Namhyung Kim wrote: > 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....@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.
The old logical will return directly whenever prev_cpu or this cpu idle, but your new logical just has one chance. > > Thanks, > Namhyung > -- Thanks Alex -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
