From owner-freebsd-smp  Fri Dec 13 17:46:02 1996
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To: Steve Passe <smp@csn.net>
cc: "Erich Boleyn,,,," <erich@uruk.org>, smp@freebsd.org
Subject: Re: Tried SMP kernel from early morning CVS tree 
In-reply-to: Your message of "Fri, 13 Dec 1996 18:08:09 MST."
             <199612140108.SAA09847@clem.systemsix.com> 
Date: Sat, 14 Dec 1996 09:45:16 +0800
From: Peter Wemm <peter@spinner.dialix.com>
Sender: owner-smp@freebsd.org
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Steve Passe wrote:
> Hi,
> 
> > Hi all.  I tried the SMP kernel from the CVS tree from early this
> > morning.  It still has the problem on my 4-CPU Pentium Pro test box
> > where a long compile kills it by getting a kernel page fault in
> > pmap_enter.
> 
> I wish I knew how to help with this, but I have neither a P6 machine or
> skills/knowledge in this area...  I've been taking advantage of the lull to
> go thru my code and cleanup a lot of little details that have fallen
> thru the cracks.

Same here, but I've been out of action for different reasons (like:
doing some final work on a new house and preparing to move).

There were some good details posted on this problem a few days ago
from the other person with the P6 system, there is probably a good
clue in there.  My initial reaction to the details was that it
almost looked like both cpu's accessed a shared data structure at
nearly the same time, which should be impossible due to the locking.
I can't imagine why this might be happening yet, but I must re-examine
that part of the code.  An extra local tlb flush might help, but
I'm not 100% sure yet.

On the other hand:
% uname -a
FreeBSD spinner.DIALix.COM 3.0-SMP FreeBSD 3.0-SMP #154: Thu Dec  5 02:26:10 WST 1996     peter@spinner.DIALix.COM:/home/peter/smp/sys/compile/SMP  i386
% uptime
 9:38AM  up 9 days,  7:04, 12 users, load averages: 0.00, 0.01, 0.00

This machine has had the stuffing hammered out of it over the last
week, I'm really happy with the stability of the P5 systems apart
from the Floating point problems.  This kernel was built with
APIC_IO+APIC_LAZY+SMP_INVLTLB, and I've had none of the subtle
corruption problems that I used to have before SMP_INVLTLB.  It's
been easy to forget that it's running SMP most of the time. :-)

Cheers,
-Peter