linux-kernel - Re: [PATCH] x86_64/__iowrite32_copy: don't use string move for PIO writes

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Message-ID: <4a526e77.IPiyTZWRWfll2+00%john.gregor@qlogic.com>
Date:	Mon, 06 Jul 2009 14:36:55 -0700
From:	john.gregor@...gic.com (John A. Gregor)
To:	hpa@...or.com
Cc:	ralph.campbell@...gic.com, linux-kernel@...r.kernel.org,
	johng@...mond.mv.qlogic.com
Subject: Re: [PATCH] x86_64/__iowrite32_copy: don't use string move for PIO
 writes

"H. Peter Anvin" <hpa@...or.com> wrote:

> John Gregor wrote:
> > From: John Gregor <johng@...mond.mv.qlogic.com>
> > 
> > Some processors can write the same word more than once if the movs
> > instruction is used. This version uses normal memory move instructions
> > and gets the same performance since the speed is limited by PCIe and
> > write combining.
> > 
>
> Which processors do that *when addressing I/O memory*?

Nehalem.

-John Gregor
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