LAM MPI on dual processor opteron box sees only one cpu...
obrien at freebsd.org
Mon Apr 19 20:32:11 PDT 2004
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
> 96090 jracine 131 0 7148K 2172K CPU1 1 0:19 44.53% 44.53%
> 96088 jracine 125 0 7148K 2172K RUN 0 0:18 43.75% 43.75%
> 96089 jracine 136 0 7148K 2172K RUN 1 0:19 42.19% 42.19%
> 96087 jracine 135 0 7188K 2248K RUN 0 0:19 41.41% 41.41%
> 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
2. Have you tried with the 4.4BSD scheduler vs. the "ULE" scheduler?
To test, replace:
options SCHED_ULE # ULE scheduler
options SCHED_4BSD #4BSD scheduler
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