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Subject: Re: [PATCH 0/5] make slab gfp fair
From: Peter Zijlstra <a.p.zijlstra@chello.nl>
To: Christoph Lameter <clameter@sgi.com>
Cc: Matt Mackall <mpm@selenic.com>, linux-kernel@vger.kernel.org,
       linux-mm@kvack.org, Thomas Graf <tgraf@suug.ch>,
       David Miller <davem@davemloft.net>,
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       Pekka Enberg <penberg@cs.helsinki.fi>
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Date: Wed, 16 May 2007 08:59:31 +0200
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On Tue, 2007-05-15 at 15:02 -0700, Christoph Lameter wrote:
> On Tue, 15 May 2007, Peter Zijlstra wrote:
> 
> > How about something like this; it seems to sustain a little stress.
> 
> Argh again mods to kmem_cache.

Hmm, I had not understood you minded that very much; I did stay away
from all the fast paths this time.

The thing is, I wanted to fold all the emergency allocs into a single
slab, not a per cpu thing. And once you loose the per cpu thing, you
need some extra serialization. Currently the top level lock is
slab_lock(page), but that only works because we have interrupts disabled
and work per cpu.

Why is it bad to extend kmem_cache a bit?