Messages in this thread | ![/](/images/icornerl.gif) | | Date | Mon, 05 May 2014 10:08:31 +0530 | From | Preeti U Murthy <> | Subject | Re: [PATCH RFC/TEST] sched: make sync affine wakeups work |
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On 05/04/2014 05:34 PM, Mike Galbraith wrote: > On Sun, 2014-05-04 at 17:14 +0530, Preeti Murthy wrote: >> Hi Rik, Mike >> >> On Fri, May 2, 2014 at 12:00 PM, Rik van Riel <riel@redhat.com> wrote: >>> On 05/02/2014 02:13 AM, Mike Galbraith wrote: >>>> On Fri, 2014-05-02 at 00:42 -0400, Rik van Riel wrote: >>>> >>>>> Whether or not this is the right thing to do remains to be seen, >>>>> but it does allow us to verify whether or not the wake_affine >>>>> strategy of always doing affine wakeups and only disabling them >>>>> in a specific circumstance is sound, or needs rethinking... >>>> >>>> Yes, it needs rethinking. >>>> >>>> I know why you want to try this, yes, select_idle_sibling() is very much >>>> a two faced little bitch. >>> >>> My biggest problem with select_idle_sibling and wake_affine in >>> general is that it will override NUMA placement, even when >>> processes only wake each other up infrequently... >> >> As far as my understanding goes, the logic in select_task_rq_fair() >> does wake_affine() or calls select_idle_sibling() only at those >> levels of sched domains where the flag SD_WAKE_AFFINE is set. >> This flag is not set at the numa domain and hence they will not be >> balancing across numa nodes. So I don't understand how >> *these functions* are affecting NUMA placements. > > Depends on how far away node yonder is I suppose. > > static inline int sd_local_flags(int level) > { > if (sched_domains_numa_distance[level] > RECLAIM_DISTANCE) > return 0; > > return SD_BALANCE_EXEC | SD_BALANCE_FORK | SD_WAKE_AFFINE; > } > >
Hmm thanks Mike, I totally missed this!
Regards Preeti U Murthy
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