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 <r...@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
--
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/
