Messages in this thread | | | Date | Fri, 15 Jul 2016 09:37:33 +0100 | From | Morten Rasmussen <> | Subject | Re: [PATCH v2 07/13] sched/fair: Let asymmetric cpu configurations balance at wake-up |
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On Thu, Jul 14, 2016 at 03:45:17PM +0200, Vincent Guittot wrote: > On 13 July 2016 at 18:14, Morten Rasmussen <morten.rasmussen@arm.com> wrote: > > On Wed, Jul 13, 2016 at 02:56:41PM +0200, Vincent Guittot wrote: > >> On 22 June 2016 at 19:03, Morten Rasmussen <morten.rasmussen@arm.com> wrote: > >> > Currently, SD_WAKE_AFFINE always takes priority over wakeup balancing if > >> > SD_BALANCE_WAKE is set on the sched_domains. For asymmetric > >> > configurations SD_WAKE_AFFINE is only desirable if the waking task's > >> > compute demand (utilization) is suitable for all the cpu capacities > >> > available within the SD_WAKE_AFFINE sched_domain. If not, let wakeup > >> > >> instead of "suitable for all the cpu capacities available within the > >> SD_WAKE_AFFINE sched_domain", should it be "suitable for local cpu and > >> prev cpu" becasue you only check the capacity of these 2 CPUs. > > > > Good point. I currently make the implicit assumption that capacity of local cpu > > and prev cpu represent the capacity for all cpus their SD_WAKE_AFFINE > > domains. It breaks if you should choose to have SD_WAKE_AFFINE on a > > domain that spans both little and big cpus, as if local/prev cpu happens > > to be big we assume that they are all big and let select_idle_sibling() > > handle the task placement even for big tasks if local/prev cpu are both > > big. > > Isn't the sd_llc used in select_idle_sibling and not the > SD_WAKE_AFFINE domian so if CPUs in the sd_llc are homogeneous, we are > safe
Yes, I confused myself (again) with SD_WAKE_AFFINE and sd_llc in the above. It should have been sd_llc instead of SD_WAKE_AFFINE. I will fix the commit message to be correct.
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