Re: [PATCH -v2 5/5] x86: use dmi check to treat disabled cpus ashotplug cpus.

[Andi Kleen]

On Wed, Jan 13, 2010 at 02:49:18PM -0800, Suresh Siddha wrote:
> On Wed, 2010-01-13 at 14:36 -0800, H. Peter Anvin wrote:
> > On 01/13/2010 02:29 PM, Suresh Siddha wrote:
> > >>
> > >> Well, that *is* working around broken code, in this case the broken code
> > >> is the percpu allocation strategy.
> > > 
> > > Andi, Recently percpu folks changed the per-cpu static first chunk to
> > > PMD SIZE right. I think that is what causing all this issue.
> > > 
> > 
> > Please don't tell me we're allocating 2 MB per CPU and throwing away
> > most of it...
> 
> Looking at the percpu code, they do seem to free the unused memory in
> that hole.

I took a look at alloc_percpu() at least and it seems to always
allocate for all possible cpus.

Unfortunately we don't have a nice accounting mechanism for it in /proc,
perhaps we should. So it's unclear right now if that is a problem or not.

-Andi

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