On Wed, Mar 22, 2017 at 01:37:28PM +0100, Peter Zijlstra wrote: > On Tue, Mar 21, 2017 at 04:52:24PM +0900, Byungchul Park wrote: > > When cpudl_find() returns any among free_cpus, the cpu might not be > > closer than others, considering sched domain. For example: > > > > this_cpu: 15 > > free_cpus: 0, 1,..., 14 (== later_mask) > > best_cpu: 0 > > > > topology: > > > > 0 --+ > > +--+ > > 1 --+ | > > +-- ... --+ > > 2 --+ | | > > +--+ | > > 3 --+ | > > > > ... ... > > > > 12 --+ | > > +--+ | > > 13 --+ | | > > +-- ... -+ > > 14 --+ | > > +--+ > > 15 --+ > > > > In this case, it would be best to select 14 since it's a free cpu and > > closest to 15(this_cpu). However, currently the code select 0(best_cpu) > > even though that's just any among free_cpus. Fix it. > > This would result in picking the HT sibling, if available. Which is > typically the worst possible pick. > > If you add support for SD_PREFER_SIBLING, which denotes a preference for > any other sibling domain above this one, this might work.
Sure. I will add that support as well. Thank you.
