You have to tell mpiexec what nodes you want to use for your application. This is typically done either on the command line or in a file. For now, you could just do this:

mpiexec -host node1,node2,node3 -np N ./my_app

where node1,node2,node3,...  are the names or IP addresses of the nodes you want to run on, and N is the number of total processes you want executed.


On Apr 19, 2011, at 8:47 AM, mohd naseem wrote:


sorry sir,

i am unable to understand what u are saying ? becoz i am a new user of mpi.

please tell me details about it and command also

thanks


 
On Tue, Apr 19, 2011 at 2:32 PM, Reuti <reuti@staff.uni-marburg.de> wrote:
Good, then please supply a hostfile with the names of the machines you want to run for a particular run and give it as option to `mpiexec`. See options -np and -machinefile.

-- Reuti


Am 19.04.2011 um 06:38 schrieb mohd naseem:

> sir
> when i give mpiexec hostname command.
> it only give one hostname. rest are not shown.
>
>
>
>
>
>
> On Mon, Apr 18, 2011 at 7:46 PM, Reuti <reuti@staff.uni-marburg.de> wrote:
> Am 18.04.2011 um 15:40 schrieb chenjie gu:
>
> > I am a green hand on Openmpi, I have the following Openmpi structure, however it has problem when running across multiple nodes.
> > I am trying to build a Bewolf Cluster between 6 nodes of our serve (HP Proliant G460 G7), I have installed the Openmpi on one node (assuming at /mirror),
> > ./configure --prefix=/mirror/openmpi CC=icc CXX=icpc F77=ifort FC=ifort
> > make all install
> >
> > using NFS, the directory of /mirror was successfully exported to the rest of 5 nodes. Now as I test the Openmpi, it runs very well on a single node,
> > however it hangs across multiple nodes.
> >
> > Now one possible reason as I know is that Openmpi uses TCP to exchange data between different nodes, so I am worried about
> > whether there are firewalls between each nodes, which can be factory integrated at somewhere(switch/NIC). Could anyone give me some
> > information on this point?
>
> It's not only about MPI communcation. Before you need some means to allow the startup of the local orte daemons on each machine by passphraseless ssh-keys or better hostbased authentication http://arc.liv.ac.uk/SGE/howto/hostbased-ssh.html , or enable `rsh` on the machines and tell Open MPI to use it. Is:
>
> mpiexec hostname
>
> giving you a list of the involved machines?
>
> -- Reuti
>
>
> > Thanks a lot,
> > Regards,
> > ArchyGU
> > Nanyang Technological University
> > _______________________________________________
> > users mailing list
> > users@open-mpi.org
> > http://www.open-mpi.org/mailman/listinfo.cgi/users
>
>
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