linux-kernel - Re: [patch 2/3] slub: scan partial list for free slabs when thrashing

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Message-ID: <alpine.DEB.1.10.0903301033380.13333@qirst.com>
Date:	Mon, 30 Mar 2009 10:37:48 -0400 (EDT)
From:	Christoph Lameter <cl@...ux.com>
To:	David Rientjes <rientjes@...gle.com>
cc:	Pekka Enberg <penberg@...helsinki.fi>,
	Nick Piggin <nickpiggin@...oo.com.au>,
	Martin Bligh <mbligh@...gle.com>, linux-kernel@...r.kernel.org
Subject: Re: [patch 2/3] slub: scan partial list for free slabs when
 thrashing

On Sun, 29 Mar 2009, David Rientjes wrote:

> Whenever a cpu cache satisfies a fastpath allocation, a fastpath counter
> is incrememted.  This counter is cleared whenever the slowpath is
> invoked.  This tracks how many fastpath allocations the cpu slab has
> fulfilled before it must be refilled.

That adds fastpath overhead and it shows for small objects in your tests.

> A new statistic, /sys/kernel/slab/cache/deferred_partial, indicates how
> many times a partial list was deferred because no slabs could satisfy
> the requisite number of objects for CONFIG_SLUB_STATS kernels.

Interesting approach.

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