linux-kernel - Re: [PATCH RFC] [X86] performance improvement for memcpy

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Date:	Mon, 9 Nov 2009 19:54:34 +0100
From:	Andi Kleen <andi@...stfloor.org>
To:	"H. Peter Anvin" <hpa@...or.com>
Cc:	Andi Kleen <andi@...stfloor.org>, "Ma, Ling" <ling.ma@...el.com>,
	Ingo Molnar <mingo@...hat.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH RFC] [X86] performance improvement for memcpy_64.S by
	fast string.

> Ling's numbers didn't seem to show a significant slowdown on Core 2 (it
> was something like 0.95x baseline in the worst case, and most of the
> cases were positive) so Core 2 doesn't seem to have a problem.

I ran quite a lot of micro benchmarks with various alignments and sizes
the 'q' variant was not always a win. I haven't checked that particular
version though.

There's also K8 of course.

-Andi
-- 
ak@...ux.intel.com -- Speaking for myself only.
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