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Date: Wed, 4 Mar 2009 10:06:49 -0800 (PST)
From: David Rientjes <rientjes@google.com>
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To: Christoph Lameter <cl@linux-foundation.org>
cc: Paul Menage <menage@google.com>, Pekka Enberg <penberg@cs.helsinki.fi>,
       Andrew Morton <akpm@linux-foundation.org>,
       Randy Dunlap <randy.dunlap@oracle.com>, linux-kernel@vger.kernel.org
Subject: Re: [patch 2/2] slub: enforce cpuset restrictions for cpu slabs
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On Wed, 4 Mar 2009, Christoph Lameter wrote:

> That would make the per object memory policies in SLUB configurable? If
> you can do that without regression and its clean then it would be
> acceptable.
> 

Yes, if `slab_hardwall' is enabled for a cpuset it will attempt to replace 
the cpu slab with a partial slab on an allowed node.

> Again if you want per object memory policies in SLUB then it needs to be
> added consistently. You would also f.e. have to check for an MPOL_BIND
> condition where you check for cpuset nodes and make sure that __slab_alloc
> goes round robin on MPOL_INTERLEAVE etc etc. You end up with a similar
> nightmare implementation of that stuff as in SLAB.

I agree that we should avoid adding mempolicy support, especially 
MPOL_INTERLEAVE at the object level since that would totally avoid the 
fastpath for any task using it.