Subject: Re: [PATCH 2.6.14] mm: 8xx MM fix for

From: Marcelo Tosatti <[email-masked]>
Date: Mon, 7 Nov 2005 08:27:19 -0200

On Mon, Nov 07, 2005 at 09:35:59AM -0500, Dan Malek wrote:
> 
> On Nov 7, 2005, at 3:44 AM, Marcelo Tosatti wrote:
> 
> >Dan, I wonder why we just don't go back to v2.4 behaviour. It is not 
> >very
> >clear to me that "two exception" speedup offsets the additional code 
> >required
> >for "one exception" version. Have you actually done any measurements?
> 
> No, and I didn't actually make these changes, either :-)

Ahh, ok. sorry. I remember you arguing that it was faster this way (less
code).

> I'm working on some 8xx debugging right now, so let's experiment
> with some changes.  I don't understand why other processors, especially
> G2 cores like 82xx, aren't finding the same problems we are having
> with 8xx.  Logically, we are all doing the same thing, unless there are
> some tlb invalidates on these other processors that I'm forgetting 
> about.

I really dont know how the 82xx TLB works, so...

> We just seem to be running into stale entries, and we have to fix it.

Right - the issue Joakim noted would be one reason for the "two exception"
approach.