linux-kernel - Re: [PATCH 0/4] slab: implement byte sized indexes for the freelist of a slab

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Date:	Tue, 3 Sep 2013 14:15:42 +0000
From:	Christoph Lameter <cl@...ux.com>
To:	Joonsoo Kim <iamjoonsoo.kim@....com>
cc:	Pekka Enberg <penberg@...nel.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Joonsoo Kim <js1304@...il.com>,
	David Rientjes <rientjes@...gle.com>, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 0/4] slab: implement byte sized indexes for the freelist
 of a slab

On Mon, 2 Sep 2013, Joonsoo Kim wrote:

> This patchset implements byte sized indexes for the freelist of a slab.
>
> Currently, the freelist of a slab consist of unsigned int sized indexes.
> Most of slabs have less number of objects than 256, so much space is wasted.
> To reduce this overhead, this patchset implements byte sized indexes for
> the freelist of a slab. With it, we can save 3 bytes for each objects.
>
> This introduce one likely branch to functions used for setting/getting
> objects to/from the freelist, but we may get more benefits from
> this change.
>
> Below is some numbers of 'cat /proc/slabinfo' related to my previous posting
> and this patchset.

You  may also want to run some performance tests. The cache footprint
should also be reduced with this patchset and therefore performance should
be better.

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