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Date: Thu, 07 Jul 2011 21:52:51 +0300
From: Pekka Enberg <penberg@...nel.org>
To: Christoph Lameter <cl@...ux.com>
Cc: Marcin Slusarz <marcin.slusarz@...il.com>,
Matt Mackall <mpm@...enic.com>,
LKML <linux-kernel@...r.kernel.org>, rientjes@...gle.com,
linux-mm@...ck.org
Subject: Re: [PATCH] slub: reduce overhead of slub_debug
On Thu, 7 Jul 2011, Pekka Enberg wrote:
> > Looks good to me. Christoph, David, ?
On Thu, 2011-07-07 at 13:17 -0500, Christoph Lameter wrote:
> The reason debug code is there is because it is useless overhead typically
> not needed. There is no point in optimizing the code that is not run in
> production environments unless there are gross performance issues that
> make debugging difficult. A performance patch for debugging would have to
> cause significant performance improvements. This patch does not do that
> nor was there such an issue to be addressed in the first place.
Is there something technically wrong with the patch? Quoting the patch
email:
(Compiling some project with different options)
make -j12 make clean
slub_debug disabled: 1m 27s 1.2 s
slub_debug enabled: 1m 46s 7.6 s
slub_debug enabled + this patch: 1m 33s 3.2 s
check_bytes still shows up high, but not always at the top.
That's significant enough speedup for me!
Pekka
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