linux-kernel - Re: [Q] Default SLAB allocator

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Message-ID: <1350392160.3954.986.camel@edumazet-glaptop>
Date:	Tue, 16 Oct 2012 14:56:00 +0200
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	Ezequiel Garcia <elezegarcia@...il.com>
Cc:	David Rientjes <rientjes@...gle.com>,
	Andi Kleen <andi@...stfloor.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	linux-mm@...ck.org, Tim Bird <tim.bird@...sony.com>,
	celinux-dev@...ts.celinuxforum.org
Subject: Re: [Q] Default SLAB allocator

On Tue, 2012-10-16 at 09:35 -0300, Ezequiel Garcia wrote:

> Now, returning to the fragmentation. The problem with SLAB is that
> its smaller cache available for kmalloced objects is 32 bytes;
> while SLUB allows 8, 16, 24 ...
> 
> Perhaps adding smaller caches to SLAB might make sense?
> Is there any strong reason for NOT doing this?

I would remove small kmalloc-XX caches, as sharing a cache line
is sometime dangerous for performance, because of false sharing.

They make sense only for very small hosts.



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