Subject: Question about r4k_clear_page_xxx()

From: Rani Assaf <[email-masked]>
Date: Wed, 10 Apr 2002 04:14:08 +0200

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()??

Regards,
Rani

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From: Florian Lohoff <[email-masked]>
Date: Wed, 10 Apr 2002 13:10:14 +0200

> 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                  [email-masked]             +49-5201-669912
Nine nineth on september the 9th              Welcome to the new billenium

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From: Ralf Baechle <[email-masked]>
Date: Thu, 11 Apr 2002 22:04:01 -0700

> not r4k_copy_page_xxx()??

The 32-bit kernel doesn't save or restore the upper 32-bits of general
purpose registers.  Therefore 64-bit stores can only be used with the
$zero register.

  Ralf