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Date:      Fri, 04 Jun 1999 20:20:56 +0200
From:      Christoph Splittgerber <cs@sdata.de>
To:        John Reynolds~ <jreynold@sedona.ch.intel.com>
Cc:        freebsd-stable@freebsd.org
Subject:   Re: Bug in SMP Kernel in 3.1, was it fixed in 3.2?
Message-ID:  <37581908.76DF506C@sdata.de>
References:  <19990603104448.24898.rocketmail@web118.yahoomail.com> <3756F682.9CA5E2B3@sdata.de> <3757A071.422E1984@wtb.tue.nl> <3757F57B.AE8A68B8@sdata.de> <14167.63562.830344.476388@hip186.ch.intel.com>

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John Reynolds~ wrote:

> Other than that wierd problem with 'top' does SMP work OK on the P2B-DS? I
> bought this motherboard about 2 months ago. I only have one PII in it now
> but was planning on putting the other in sometime towards the end of the
> summer.
> 
> Do you think it's some thing with top, kernel data structures, or do you
> believe the 2nd CPU is slowly being "shut off" (i.e. can you do something
> really intense like "make -j 2 buildworld" w/ and w/o SMP and measure the
> wall-clock time?).
> 
> What BIOS do you have loaded in there. I recently upgraded to BIOS 1009
> (which contains an upgrade of adaptec's scsi bios to v2.11) and it helped
> me actually install 3.1-RELEASE on this box (haven't had time to CVSup to
> 3.2-STABLE yet).
> 

John,

I really don't know about the source of the problem. It's just the %CPU
and
%WCPU that decrease to 0.00 a short while after booting. The process
time
is accumulated ok I think. Yes, I'm sure that both CPU's are running - I
have 2 "setiathome jobs" (see http://setiathome.ssl.berkeley.edu) niced
at -19 running all the time in the background. These jobs are absolutely
cpu intensive and take 100% of the CPU if they can. One job finishes in
about 10h, 2 jobs also finish in about 10h and in top I see the run
state
changes between RUN, CPU0, CPU1.

I recognized one other strange behaviour: If I have these to seti jobs
running
disk access becomes very slow - even if I "idprio" them down as far as
possible.
A simple "ls -ls" may take a couple of seconds in a directory with only
100
entries. If I stop just one of the background jobs, disk access is fast
as ever.
I don't see this on my other single-cpu FreeBSD machines, they all run a
seti-job in the background and besides taking some memory they don't
slow down
anything when running at nice -19. However, all single-cpu hosts have a
AHA2940(UW)
controller, so maybe this is specific to the aic7890/91 chipset and not
a SMP
problem at all. The BIOS here is Rev. 1008 (I think) so maybe I should
get an
update.

However, besides these two minor problems, the machine runs without any
problems
since 2 month now.

Christoph


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