Re: [PATCHSET] percpu: generalize first chunk allocators and improve lpage NUMA support

From: Andi Kleen
Date: Wed Jun 24 2009 - 20:02:23 EST


> I assume from the tremendous number of for_each_possible_cpu()s that
> CPU hotplug awareness won't be happening.
>
> Do we have a feeling for the amount of wastage here? If
>
> num_possible_cpus() - num_online_cpus() == N

Haven't read the new patches, but per cpu data always was sized
for all possible CPUs.

> and N is large, what did it cost?

> And what are reasonable values of N?

N should normally not be large anymore, since num_possible_cpus()
is sized based on firmware information now.

-Andi

--
ak@xxxxxxxxxxxxxxx -- Speaking for myself only.
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