Date: Mon, 19 Apr 2004 20:32:08 -0700 From: "David O'Brien" <obrien@freebsd.org> To: Jeffrey Racine <jracine@maxwell.syr.edu> Cc: freebsd-cluster@freebsd.org Subject: Re: LAM MPI on dual processor opteron box sees only one cpu... Message-ID: <20040420033208.GB98258@dragon.nuxi.com> In-Reply-To: <1081775064.990.13.camel@x1-6-00-b0-d0-c2-67-0e.twcny.rr.com> References: <024f01c41ffa$029327e0$0c03a8c0@internal.thebeatbox.org> <1081775064.990.13.camel@x1-6-00-b0-d0-c2-67-0e.twcny.rr.com>
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On Mon, Apr 12, 2004 at 09:04:24AM -0400, Jeffrey Racine wrote:
> Hi Roland.
>
> I do get CPU #1 launched. This is not the problem.
>
> The problem appears to be with the way that current is scheduling.
>
> With mpirun np 2 I get the job running on CPU 0 (two instances on one
> proc). However, it turns out that with np 4 I get the job running on CPU
> 0 and 1 though with 4 instances (and associated overhead). Here is top
> for np 4... notice that in the C column it is using both procs.
>
> PID USERNAME PRI NICE SIZE RES STATE C TIME WCPU CPU
> COMMAND
> 96090 jracine 131 0 7148K 2172K CPU1 1 0:19 44.53% 44.53%
> n_lam
> 96088 jracine 125 0 7148K 2172K RUN 0 0:18 43.75% 43.75%
> n_lam
> 96089 jracine 136 0 7148K 2172K RUN 1 0:19 42.19% 42.19%
> n_lam
> 96087 jracine 135 0 7188K 2248K RUN 0 0:19 41.41% 41.41%
> n_lam
>
>
> One run (once when I rebooted lam) did allocate the job correctly with
> np 2, but this is not in general the case. On other systems I use,
> however, they correctly farm out np 2 to CPU 0 and 1...
>
> Thanks, and any suggestions welcome.
1. Please don't top-post -- it looses context. This is a Unix list, not
Mikeysoft one.
2. Have you tried with the 4.4BSD scheduler vs. the "ULE" scheduler?
To test, replace:
options SCHED_ULE # ULE scheduler
with
options SCHED_4BSD #4BSD scheduler
-- David
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