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Re: _clear_page semantics

To: Carsten Langgaard <carstenl@mips.com>
Subject: Re: _clear_page semantics
From: Ralf Baechle <ralf@oss.sgi.com>
Date: Wed, 10 Jan 2001 13:34:39 -0200
Cc: carlson@sibyte.com, linux-mips@oss.sgi.com
In-reply-to: <3A5C1868.A6B54E57@mips.com>; from carstenl@mips.com on Wed, Jan 10, 2001 at 09:08:08AM +0100
References: <01010917590106.07691@plugh.sibyte.com> <3A5C1868.A6B54E57@mips.com>
Sender: owner-linux-mips@oss.sgi.com
User-agent: Mutt/1.2.5i
On Wed, Jan 10, 2001 at 09:08:08AM +0100, Carsten Langgaard wrote:

> You are absolutely right, it is implementation dependent.
> I just tend to use the mips32 implementation for my R4000s as well, and here 
> as
> Ralf mention it is performance improving.
> Actually we have included a CPU option flag (MIPS_CPU_CACHE_CDEX), what tells 
> us
> if the CPU has the Create_Dirty_Exclusive CACHE operation available.
> So we should probably use it, now it is here :-)

Homework for somebody with some time at his hands - we have a large number
of unrolled loops for all sorts of cache variations in r4xx0.c.  Benchmark
if they actually improve performance.  I wouldn't wonder if due to a large
number of pipeline stalls in one of those routines the whole unrolling
business doesn't buy us anything.

  Ralf

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