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Date: Tue, 9 Oct 2007 12:15:58 -0700 (PDT)
From: Christoph Lameter <clameter@sgi.com>
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To: Pekka Enberg <penberg@cs.helsinki.fi>
cc: Akinobu Mita <akinobu.mita@gmail.com>, linux-kernel@vger.kernel.org,
       Andrew Morton <akpm@linux-foundation.org>, travis@sgi.com
Subject: Re: [PATCH -mm] slub: fix cpu hotplug offline/online path
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On Tue, 9 Oct 2007, Pekka Enberg wrote:

> Hi Christoph,
> 
> On 10/9/07, Christoph Lameter <clameter@sgi.com> wrote:
> > Our system come by default with the possibility of 1k cpus. However, a
> > small system may only have 8 cpus.
> 
> Maybe I am reading the code wrong, but I don't why that matters as
> it's all statically allocated anyway (the per-cpu kmem_cache_cpu
> array). In any case, I certainly don't object to your proposal, just
> can't figure out why it matters.

The kmem_cache_cpu structures are allocated using DEFINE_PER_CPU. 

The per cpu areas should be dynamically allocated as necessary. There is 
work in progress by Mike Travis to do that. You are right in that (on 
x86_64 at least) we define a static array for all processors.