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Date: Tue, 2 Aug 2011 09:10:46 -0500 (CDT)
From: Christoph Lameter <cl@linux.com>
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To: David Rientjes <rientjes@google.com>
cc: Pekka Enberg <penberg@cs.helsinki.fi>, Andi Kleen <andi@firstfloor.org>,
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        Matt Mackall <mpm@selenic.com>, Eric Dumazet <eric.dumazet@gmail.com>,
        Adrian Drzewiecki <z@drze.net>, linux-kernel@vger.kernel.org
Subject: Re: [slub p3 0/7] SLUB: [RFC] Per cpu partial lists V3
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On Mon, 1 Aug 2011, David Rientjes wrote:

>
> This applied nicely to Linus' tree so I've moved to testing atop that
> rather than slub/lockless on the same netperf testing environment as the
> slab vs. slub comparison.  The benchmarking completed without error and
> here are the results:
>
> 	threads		before		after
> 	 16		75509		75443  (-0.1%)
> 	 32		118121		117558 (-0.5%)
> 	 48		149997		149514 (-0.3%)
> 	 64		185216		186772 (+0.8%)
> 	 80		221195		222612 (+0.6%)
> 	 96		239732		241089 (+0.6%)
> 	112		261967		266643 (+1.8%)
> 	128		272946		281794 (+3.2%)
> 	144		279202		289421 (+3.7%)
> 	160		285745		297216 (+4.0%)
>
> So the patchset certainly looks helpful, especially if it improves other
> benchmarks as well.

The problem is that the partial approach has not been fine tuned yet for
these larger loads. And the proper knobs are not implemented yet.

> I'll review the patches individually, starting with the cleanup patches
> that can hopefully be pushed quickly while we discuss per-cpu partial
> lists further.

I am currently reworking the patches to operate on a linked list instead
of a very small array of pointers to page structs. That will allow much
larger per cpu partial lists and a dynamic configuration of the sizes.