linux-kernel - Re: [PATCH v3 3/5] slab: restrict the number of objects in a slab

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Message-ID: <alpine.DEB.2.02.1401142105380.7751@chino.kir.corp.google.com>
Date:	Tue, 14 Jan 2014 21:05:50 -0800 (PST)
From:	David Rientjes <rientjes@...gle.com>
To:	Joonsoo Kim <iamjoonsoo.kim@....com>
cc:	Pekka Enberg <penberg@...nel.org>,
	Christoph Lameter <cl@...ux.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Wanpeng Li <liwanp@...ux.vnet.ibm.com>, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org, Joonsoo Kim <js1304@...il.com>
Subject: Re: [PATCH v3 3/5] slab: restrict the number of objects in a slab

On Mon, 2 Dec 2013, Joonsoo Kim wrote:

> To prepare to implement byte sized index for managing the freelist
> of a slab, we should restrict the number of objects in a slab to be less
> or equal to 256, since byte only represent 256 different values.
> Setting the size of object to value equal or more than newly introduced
> SLAB_OBJ_MIN_SIZE ensures that the number of objects in a slab is less or
> equal to 256 for a slab with 1 page.
> 
> If page size is rather larger than 4096, above assumption would be wrong.
> In this case, we would fall back on 2 bytes sized index.
> 
> If minimum size of kmalloc is less than 16, we use it as minimum object
> size and give up this optimization.
> 
> Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@....com>

Acked-by: David Rientjes <rientjes@...gle.com>
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