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Re: Question about r4k_clear_page_xxx()

To: Rani Assaf <rani@paname.org>
Subject: Re: Question about r4k_clear_page_xxx()
From: Florian Lohoff <flo@rfc822.org>
Date: Wed, 10 Apr 2002 13:10:14 +0200
Cc: linux-mips@oss.sgi.com
In-reply-to: <20020410041408.G23127@paname.org>
Organization: rfc822 - pure communication
References: <20020410041408.G23127@paname.org>
Sender: owner-linux-mips@oss.sgi.com
User-agent: Mutt/1.3.28i
On Wed, Apr 10, 2002 at 04:14:08AM +0200, Rani Assaf wrote:
> Hi,
> 
> I was cleaning  duplicate code between my port of  IDT RC32355 and the
> current tree. I want to use r4k_clear_page_d16() but the function uses
> store double (sd) which is not available on this processor.
> 
> What's the reason for having r4k_clear_page_xxx() use store double and
> not r4k_copy_page_xxx()??

Just from my guess - r4k_copy_page will pollute the d-cache with the
empty page you are reading. You have twice as much instruction (load +
store) which effectively will give you half the performance.

If "sd" is not available you might want to implement your clear_page
with sw zero, x(a0) like the sd version.

Flo
-- 
Florian Lohoff                  flo@rfc822.org             +49-5201-669912
Nine nineth on september the 9th              Welcome to the new billenium

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