Message-ID: <4AF84640.7010705@zytor.com>
Date: Mon, 09 Nov 2009 08:41:36 -0800
From: "H. Peter Anvin" <hpa@zytor.com>
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To: Andi Kleen <andi@firstfloor.org>
CC: "Ma, Ling" <ling.ma@intel.com>, Ingo Molnar <mingo@redhat.com>,
       Thomas Gleixner <tglx@linutronix.de>,
       linux-kernel <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH RFC] [X86] performance improvement for memcpy_64.S by
 fast string.
References: <1257500482-16182-1-git-send-email-ling.ma@intel.com>	<4AF457E0.4040107@zytor.com> <4AF4784C.5090800@zytor.com>	<8FED46E8A9CA574792FC7AACAC38FE7714FCF772C9@PDSMSX501.ccr.corp.intel.com>	<4AF7C66C.6000009@zytor.com> <87ws2059s9.fsf@basil.nowhere.org>
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On 11/09/2009 01:26 AM, Andi Kleen wrote:
> "H. Peter Anvin" <hpa@zytor.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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