linux-kernel - Re: [this_cpu_xx V6 7/7] this_cpu: slub aggressive use of this

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Date:	Fri, 16 Oct 2009 12:45:26 -0400 (EDT)
From:	Christoph Lameter <cl@...ux-foundation.org>
To:	David Rientjes <rientjes@...gle.com>
cc:	Mel Gorman <mel@....ul.ie>, Pekka Enberg <penberg@...helsinki.fi>,
	Tejun Heo <tj@...nel.org>, linux-kernel@...r.kernel.org,
	Mathieu Desnoyers <mathieu.desnoyers@...ymtl.ca>,
	Zhang Yanmin <yanmin_zhang@...ux.intel.com>
Subject: Re: [this_cpu_xx V6 7/7] this_cpu: slub aggressive use of this_cpu
 operations in the hotpaths

On Thu, 15 Oct 2009, David Rientjes wrote:

> TCP_STREAM stresses a few specific caches:
>
> 		ALLOC_FASTPATH	ALLOC_SLOWPATH	FREE_FASTPATH	FREE_SLOWPATH
> kmalloc-256	3868530		3450592		95628		7223491
> kmalloc-1024	2440434		429		2430825		10034
> kmalloc-4096	3860625		1036723		85571		4811779
>
> This demonstrates that freeing to full (or partial) slabs causes a lot of
> pain since the fastpath normally can't be utilized and that's probably
> beyond the scope of this patchset.
>
> It's also different from the cpu slab thrashing issue I identified with
> the TCP_RR benchmark and had a patchset to somewhat improve.  The
> criticism was the addition of an increment to a fastpath counter in struct
> kmem_cache_cpu which could probably now be much cheaper with these
> optimizations.

Can you redo the patch?

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