From: Andreas Kleen <ak@suse.de>
To: "Bryan O'Sullivan" <bos@pathscale.com>
Cc: Matt Mackall <mpm@selenic.com>, Andrew Morton <akpm@osdl.org>,
linux-kernel@vger.kernel.org
Subject: Re: [RFC] [PATCH] Add memcpy32 function
Date: Wed, 28 Dec 2005 19:22:30 +0100 (CET) [thread overview]
Message-ID: <6232114.1135794150848.SLOX.WebMail.wwwrun@imap-dhs.suse.de> (raw)
In-Reply-To: <1135793503.1527.125.camel@serpentine.pathscale.com>
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
prev parent reply other threads:[~2005-12-28 18:22 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-12-23 1:35 Bryan O'Sullivan
2005-12-23 2:49 ` Dave Jones
2005-12-23 17:16 ` Matt Mackall
2005-12-23 17:42 ` Christoph Hellwig
2005-12-23 18:14 ` Matt Mackall
2005-12-23 23:50 ` Bryan O'Sullivan
2005-12-28 11:01 ` Andi Kleen
2005-12-28 15:00 ` Bryan O'Sullivan
2005-12-28 17:50 ` Andreas Kleen
2005-12-28 18:11 ` Bryan O'Sullivan
2005-12-28 18:22 ` Andreas Kleen [this message]
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