Re: [PATCH v10 10/11] sched: add SD_PREFER_SIBLING for SMT level

[Preeti U Murthy]

On 03/23/2015 02:41 PM, Peter Zijlstra wrote:
> On Tue, Mar 03, 2015 at 09:38:11AM +0100, Vincent Guittot wrote:
> 
>>> Prefer siblings logic dates back to https://lkml.org/lkml/2009/8/27/210
>>> and only used in update_sd_lb_stats() where we have
>>>
>>> if (child && child->flags & SD_PREFER_SIBLING)
>>>          prefer_sibling = 1;
>>>
>>> However what confuses me is why should we even look at a child domain's
>>> flag to balance tasks across the current sched domain? Why cant we just
>>> set and use a sd flag at current level than to look at child domain
>>> flag?
>>
>> Peter,
>> have you got some insight about the reason ?
> 
> Yeah, because it makes sense that way? ;-)
> 
> The we want to move things to the child's sibling, not the parent's
> sibling. We further need to have a child for this to make sense.
> 
> 

+1. The above is precisely why we need this patch.

Regards
Preeti U Murthy

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/