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Subject: Re: [OMPI users] Non-homogeneous Cluster Implementation
From: jody (jody.xha_at_[hidden])
Date: 2010-01-28 02:43:52


Hi
I'm not sure i completely understood.
Is it the case that an application compiled on the dell will not work
on the PS3 and vice versa?

If this is the case, you could try this:
  shell$ mpirun -np 1 --host a app_ps3 : -np 1 --host b app_dell
where app_ps3 is your application compiled on the PS3 and a is your PS3 host,
and app_dell is your application compiled on the dell, and b is your dell host.

Check the MPI FAQs
  http://www.open-mpi.org/faq/?category=running#mpmd-run
  http://www.open-mpi.org/faq/?category=running#mpirun-host

Hope this helps
  Jody

On Thu, Jan 28, 2010 at 3:08 AM, Lee Manko <lmanko_at_[hidden]> wrote:
> OK, so please stop me if you have heard this before, but I couldn’t find
> anything in the archives that addressed my situation.
>
>
>
> I have a Beowulf cluster where ALL the node are PS3s running Yellow Dog
> Linux 6.2 and a host (server) that is a Dell i686 Quad-core running Fedora
> Core 12.  After a failed attempt at letting yum install openmpi, I
> downloaded v1.4.1, compiled and installed on all machines (PS3s and
> Dell).  I have an NSF shared directory on the host where the application
> resides after building.  All nodes have access to the shared volume and they
> can see any files in the shared volume.
>
>
>
> I wrote a very simple master/slave application where the slave does a simple
> computation and gets the processor name.  The slave returns both pieces of
> information to the master who then simply displays it in the terminal
> window.  After the slaves work on 1024 such tasks, the master exists.
>
>
>
> When I run on the host, without distributing to the nodes, I use the
> command:
>
>
>
>                 “mpirun –np 4 ./MPI_Example”
>
>
>
> Compiling and running the application on the native hardware works perfectly
> (ie: compiled and run on the PS3 or compiled and run on the Dell).
>
>
>
> However, when I went to scatter the tasks to the nodes, using the following
> command,
>
>
>
>                 “mpirun –np 4 –hostfile mpi-hostfile ./MPI_Example”
>
>
>
> the application fails.  I’m surmising that the issue is with running code
> that was compiled for the Dell on the PS3 since the MPI_Init will launch the
> application from the shared volume.
>
>
>
> So, I took the source code and compiled it on both the Dell and the PS3 and
> placed the executables in /shared_volume/Dell and /shared_volume/PS3 and
> added the paths to the environment variable PATH.  I tried to run the
> application from the host again using the following command,
>
>
>
>                 “mpirun –np 4 –hostfile mpi-hostfile –wdir
> /shared_volume/PS3 ./MPI_Example”
>
>
>
> Hoping that the wdir would set the working directory at the time of the call
> to MPI_Init() so that MPI_Init will launch the PS3 version of the
> executable.
>
>
>
> I get the error:
>
> Could not execute the executable “./MPI_Example” : Exec format error
>
> This could mean that your PATH or executable name is wrong, or that you do
> not
>
> have the necessary permissions.  Please ensure that the executable is able
> to be
>
> found and executed.
>
>
>
> Now, I know I’m gonna get some heat for this, but all of these machine use
> only the root account with full root privileges, so it’s not a permission
> issue.
>
>
>
>
>
> I am sure there is simple solution to my problem.  Replacing the host with a
> PS3 is not an option. Does anyone have any suggestions?
>
>
>
> Thanks.
>
>
>
> PS: When I get to programming the Cell BE, then I’ll use the IBM Cell SDK
> with its cross-compiler toolchain.
>
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