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Message-Id: <1178301545.24217.56.camel@twins>
Date: Fri, 04 May 2007 19:59:05 +0200
From: Peter Zijlstra <a.p.zijlstra@...llo.nl>
To: Christoph Lameter <clameter@....com>
Cc: linux-kernel@...r.kernel.org, linux-mm@...ck.org,
netdev@...r.kernel.org,
Trond Myklebust <trond.myklebust@....uio.no>,
Thomas Graf <tgraf@...g.ch>,
David Miller <davem@...emloft.net>,
James Bottomley <James.Bottomley@...elEye.com>,
Mike Christie <michaelc@...wisc.edu>,
Andrew Morton <akpm@...ux-foundation.org>,
Daniel Phillips <phillips@...gle.com>,
Pekka Enberg <penberg@...helsinki.fi>
Subject: Re: [PATCH 08/40] mm: kmem_cache_objsize
On Fri, 2007-05-04 at 09:36 -0700, Christoph Lameter wrote:
> On Fri, 4 May 2007, Peter Zijlstra wrote:
>
> > Expost buffer_size in order to allow fair estimates on the actual space
> > used/needed.
>
> If its just an estimate that you are after then I think ksize is
> sufficient.
>
> The buffer size does not include the other per slab overhead that SLAB
> needs nor the alignment overhead or the padding. For SLUB you'd be more
> lucky but there it does not include the per slab padding that exist.
>
> Need to check how this is going to be used. It is difficult to estimate
> slab use because this depends on the availability of object slots in
> partial slabs.
>
> I could add a function that tells you how many object you could allocate
> from a slab without the page allocator becoming involved? It would count
> the object slots available on the partial slabs.
I need to know how many pages to reserve to allocate a given number of
items from a given slab; assuming the partial slabs are empty. That is,
I need a worst case upper bound.
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