[Beowulf] MPI questions

[Reuti]

Jake Thebault-Spieker wrote:
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> I guess my question is how do I use MPI? Will the MPICH implementation

http://www.netlib.org/utk/papers/mpi-book/mpi-book.html
ftp://math.usfca.edu/pub/MPI/mpi.guide.ps

> work with a program written for MPI? Does one need MPICH on all of the

Yes.

> nodes, or just the master node?

For MPICH: only on the head node of your job it's necessary. But as in a 
cluster each node can become the headnode of your job, it must be 
available on all nodes in the end.

Ciao - Reuti

> 
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> Jake Thebault-Spieker
> 
> 
> 
> Jack wrote:
> 
> 
>>>What is the difference between MPI? Does MPI need to be running on all
>>>the nodes or just the node that the job was started on? Is the debian
>>>package MPICH the correct one?
>>>
>>
>>The various MPI distributions (OpenMPI, LamMPI, MPICH) all attempt
> 
> conform to a set of MPI standards. Thus, sometimes they differ slightly
> in implementation, but normally a code will run on all of them (though
> you will need to compile it usuing the correct libraries).
> 
>>About the running on the nodes question: when, for instance in the Lam
> 
> distribution, you say "lamboot <machine_list>", it goes out and starts
> the "lamd" daemon. Then, when you say "mpirun whatever", all these
> daemons on the hosts each start their process with the correct rank
> number, and they deal with the transactions between nodes.
> 
>>Is that the correct one? Sure. It will probably work, though we have no
> 
> idea exactly what you want to do.
> 
>>There are good descriptions of this sort of thing around, take a look
> 
> on The Oracle (Google).
> 
>>Have fun!
>>
>>-Jack Carrozzo
>>http://www.crepinc.com/
>>
>>
>>
>>
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