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Message-ID: <20121012231719.GA21198@liondog.tnic>
Date: Sat, 13 Oct 2012 01:17:19 +0200
From: Borislav Petkov <bp@...en8.de>
To: George Spelvin <linux@...izon.com>
Cc: linux-kernel@...r.kernel.org, Ma Ling <ling.ma@...el.com>,
x86@...nel.org
Subject: Re: [PATCH RFC 2/2] [x86] Optimize copy_page by re-arranging
instruction sequence and saving register
On Fri, Oct 12, 2012 at 05:02:57PM -0400, George Spelvin wrote:
> Here are some Phenom results for that benchmark. The average time
> increases from 700 to 760 cycles (+8.6%).
I was afraid something like that would show up.
Btw, in looking at this more and IINM, we use the REP MOVSQ version on
AMD anyway because of X86_FEATURE_REP_GOOD being set on some K8 and
everything from F10h on.
So, actually this µbenchmark should be comparing the REP MOVSQ case too
and the changes to the unrolled copy_page shouldn't concern AMD boxes
actually...
Hmm.
--
Regards/Gruss,
Boris.
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