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

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Date:	Mon, 09 Nov 2009 08:41:36 -0800
From:	"H. Peter Anvin" <hpa@...or.com>
To:	Andi Kleen <andi@...stfloor.org>
CC:	"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.

On 11/09/2009 01:26 AM, Andi Kleen wrote:
> "H. Peter Anvin" <hpa@...or.com> writes:
>>
>> My personal opinion is that if we can show no significant slowdown on
>> P4, K8, P-M/Core 1, Core 2, and Nehalem then we can simply use this code
> 
> The issue is Core 2.
> 
> P4 uses a different path, and Core 1 doesn't use the 64bit code.
> 

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.

	-hpa

-- 
H. Peter Anvin, Intel Open Source Technology Center
I work for Intel.  I don't speak on their behalf.

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