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From: Grant Grundler <grundler@parisc-linux.org>
To: James Bottomley <James.Bottomley@steeleye.com>
Cc: PARISC list <parisc-linux@lists.parisc-linux.org>
Subject: Re: [parisc-linux] PA8800/ZX1 support committed to 2.6.7-rc2-pa2
Date: Sat, 5 Jun 2004 15:05:15 -0600	[thread overview]
Message-ID: <20040605210515.GA8098@colo.lackof.org> (raw)
In-Reply-To: <1086444652.1999.20.camel@mulgrave>

On Sat, Jun 05, 2004 at 09:10:51AM -0500, James Bottomley wrote:
> Your explanation is possible, but it's highly unlikely to be an existing
> problem.  PA currently uses the big hammer approach to cache coherency
> and flushes everything on virtually every large mmu changing operation. 
> If there's a caching problem in between the flushes it should have shown
> up on much smaller cache machines as well.
> 
> Also, when doing the no flushing updates to improve fork/exec, I removed
> the global flushing so now any cache mismanagement would become
> cumulative and should definitely have been seen.

Well, I can only point at the difference in cache size.

> My money would be on an additional architectural requirement of the
> PA8800 (maybe even an existing PA one that the <PA8800 just don't need)
> that we don't respect.

yes - and we've changed chipsets too.

Any good ideas on how to prove IO is coherent?

It might be the same problem that Naresh described as "SCSI DMA problems".
I just happen to be using NFS Root instead.

But I found one bug in Naresh's port that might explain his problem
(wasn't flushing IO TLB properly). It would be interesting to hear
if 2.6.7-rc2-pa3 works better for him.

grant
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  reply	other threads:[~2004-06-05 21:05 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2004-06-04 20:25 [parisc-linux] PA8800/ZX1 support committed to 2.6.7-rc2-pa2 Grant Grundler
2004-06-05  6:51 ` Grant Grundler
2004-06-05 14:10   ` James Bottomley
2004-06-05 21:05     ` Grant Grundler [this message]
2004-06-05 21:19       ` James Bottomley
2004-06-05 22:21         ` Grant Grundler
2004-06-11  5:58         ` Grant Grundler
2004-06-11 14:02           ` James Bottomley
2004-06-11 15:03             ` Grant Grundler
2004-06-11 15:27             ` Grant Grundler
2004-06-12  0:38           ` Jim Hull
2004-06-14 18:29             ` Grant Grundler
2004-06-14 22:45               ` Jim Hull
2004-06-14 23:42                 ` Grant Grundler

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