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Date: Wed, 24 Aug 2011 08:57:55 -0500 (CDT)
From: Christoph Lameter <cl@linux.com>
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To: Lin Ming <ming.m.lin@intel.com>
cc: Pekka Enberg <penberg@cs.helsinki.fi>,
        David Rientjes <rientjes@google.com>, Andi Kleen <andi@firstfloor.org>,
        tj@kernel.org, Metathronius Galabant <m.galabant@googlemail.com>,
        Matt Mackall <mpm@selenic.com>, Eric Dumazet <eric.dumazet@gmail.com>,
        Adrian Drzewiecki <z@drze.net>, "Li, Shaohua" <shaohua.li@intel.com>,
        lkml <linux-kernel@vger.kernel.org>
Subject: Re: [slub p4 6/7] slub: per cpu cache for partial pages
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On Wed, 24 Aug 2011, Lin Ming wrote:

> > Potential future enhancements:
> >
> > 1. The pickup from the partial list could be perhaps be done without disabling
> >   interrupts with some work. The free path already puts the page into the
> >   per cpu partial list without disabling interrupts.
>
> Nice patches!
>
> Could you share possible ways for this potential enhancement?

In order to avoid disabling interrupts in the allocation paths the state
that has to be kept in kmem_cache_cpu needs to be minimized so that it can
be swapped atomically using a this_cpu_cmpxchg. This means getting rid of
the node and slab fields I guess. Working on some patches to that effect.

Once that is done one can with a this_cpu_cmpxchg_double take over the per
cpu slab and then use that information to update the slab page etc.