[mpich-discuss] How to specify number of cores for each process

Pavan Balaji balaji at mcs.anl.gov
Wed Nov 28 07:41:46 CST 2012

There are two problems in your usage below.

1. I'm guessing that your host file specifies only one core for each
host.  Something like:


Did you look through the mpiexec usage document that tells you how to
specify multiple cores on each host?


You should do something like:


(please read the documentation on the above link for more information).

2. There's option called -binding auto.  Did you mean -binding none?

 -- Pavan

On 11/27/2012 09:37 PM US Central Time, Zachary Stanko wrote:
> Hello,
> I am running an MPI program on a machine with two 16-core processors
> yet, no matter what configuration I use with mpiexec, I am only
> receiving 4 simultaneous processes.
> I would like to maximize this machine's potential and run 8 or 16
> processes. I have tried all of the channel selections and tried the
> -binding option.
> Since I need to specify a different working directory for each process
> (due to many output files with naming conflicts), I have a config file
> with 8 lines of the form:
> -n 1 -binding auto -dir <mydir01> <myprog> <inpfile>
> -n 1 -binding auto -dir <mydir02> <myprog> <inpfile>
> ...etc
> and I run:
> mpiexec -configfile <filename>
> Am I doing something wrong, or does MPICH just know best and cannot run
> more than 4 jobs at a time on this system?
> Thanks,
> Zak
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Pavan Balaji

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