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