Re: [RFC PATCH v3 0/3] sched: simplify the select_task_rq_fair()

From: Michael Wang
Date: Fri Feb 22 2013 - 04:11:05 EST


On 02/22/2013 04:21 PM, Peter Zijlstra wrote:
> On Fri, 2013-02-22 at 10:36 +0800, Michael Wang wrote:
>> According to my understanding, in the old world, wake_affine() will
>> only
>> be used if curr_cpu and prev_cpu share cache, which means they are in
>> one package, whatever search in llc sd of curr_cpu or prev_cpu, we
>> won't
>> have the chance to spread the task out of that package.
>
> Nah, look at where SD_WAKE_AFFINE is set. Only 'remote/big' NUMA domains
> don't have it set, but 'small' NUMA systems will have it set over the
> entire domain tree.

Oh, I missed that point...

But I don't get the reason to make NUMA level affine, cpus in different
nodes share cache? doesn't make sense...

Regards,
Michael Wang

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