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Subject: Re: [OMPI users] Help: How to accomplish processors affinity
From: Lenny Verkhovsky (lenny.verkhovsky_at_[hidden])
Date: 2009-08-17 02:43:59


Hi
http://www.open-mpi.org/faq/?category=tuning#using-paffinity
I am not familiar with this cluster, but in the FAQ ( see link above ) you
can find an example of the rankfile.
another simple example is the following:
$cat rankfile
rank 0=host1 slot=0
rank 1=host2 slot=0
rank 2=host3 slot=0
rank 3=host4 slot=0
$mpirun -np 4 -H host1,host2,host3,host4 -rf rankfile ./app
if you OS sees your cluster as a one machine and $cat /proc/cpuinfo shows 4
CPUs ( let's assume 0-3 ) and one IP and hostname,
then try this:
$cat rankfile
rank 0=host1 slot=0
rank 1=host1 slot=1
rank 2=host1 slot=2
rank 3=host1 slot=3
$mpirun -np 4 -H host1 -rf rankfile ./app
best regards
Lenny.

On Fri, Aug 14, 2009 at 6:50 AM, Lee Amy <openlinuxsource_at_[hidden]> wrote:

> HI,
>
> I read some howtos at OpenMPI official site but i still have some problems
> here.
>
> I build a Kerrighed Clusters with 4 nodes so they look like a big SMP
> machine. every node has 1 processor with dingle core.
>
> 1) Dose MPI programs could be running on such kinds of machine? If
> yes, could anyone show me some examples?
>
> 2) In this SMP machine there are 4 processors I could see. So how do I
> use OpenMPI to run some programs on these CPUs? Though I read how to
> make a rank file but I am still feel confused. Could anyone show me a
> simple rank file example for my Clusters?
>
> Thank you very much.
>
> Regards,
>
> Amy Lee
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