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Message-ID: <87ws2059s9.fsf@basil.nowhere.org>
Date: Mon, 09 Nov 2009 10:26:14 +0100
From: Andi Kleen <andi@...stfloor.org>
To: "H. Peter Anvin" <hpa@...or.com>
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.
"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.
> unconditionally. If one of them is radically worse than baseline, then
> we have to do something conditional, which is a lot more complicated.
I have an older patchkit which did this, and some more optimizations
to this code.
There was still one open issue, that is why I didn't post it. If there's
interest I can post it.
-Andi
--
ak@...ux.intel.com -- Speaking for myself only.
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