Message-ID: <6232114.1135794150848.SLOX.WebMail.wwwrun@imap-dhs.suse.de>
Date: Wed, 28 Dec 2005 19:22:30 +0100 (CET)
From: Andreas Kleen <ak@suse.de>
To: "Bryan O'Sullivan" <bos@pathscale.com>
Subject: Re: [RFC] [PATCH] Add memcpy32 function
Cc: Matt Mackall <mpm@selenic.com>, Andrew Morton <akpm@osdl.org>,
       linux-kernel@vger.kernel.org
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Am Mi 28.12.2005 19:11 schrieb Bryan O'Sullivan <bos@pathscale.com>:

> On Wed, 2005-12-28 at 18:50 +0100, Andreas Kleen wrote:
>
> > Ok thanks. And do you have numbers that show that the assembly
> > function with rep ; movsl actually improves performance over C?
>
> I'll see if I can ferret some numbers out. If not, I'll generate them,
> but it will take me a day or so. I'm pretty sure it makes a difference
> of tens to hundreds of nanoseconds, which in our case is very
> significant (we measure some of our user-level performance in
> increments
> of 10ns, very repeatably).

If you test the C version use

CFLAGS_memcpy32.o := -funroll-loops

BTW on x86-64 with CONFIG_UNORDERED_IO writel can actually expand to a
non temporal write which might break it.

-Andi


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