[MPICH] Specifying machinefile within MPI_Comm_spawn command

[Rajesh Sudarsan]

Hi,
I am trying out a simple example using MPI_Comm_spawn command in mpich2. 
The command works fine and it spawns new processes without any
error. But I am not able to specify on which processor node to spawn the 
process. The only argument where I thought I could enter the node
information was MPI_Info argument in the MPI_Comm_spawn command. But 
still the spawn command starts the new processes on arbitrary nodes.

I know that in the case of LAM/MPI, the node specification for spawn 
process is given as a "appshcema" file using MPI_Info argument. But the
same technique does not seem to work in mpich2.

I read the earlier posts in Jan 2006 on this similar issue, but the 
solution posted suggested to use some flags with the mpiexec command.  
The code that I am using,  spawns new processes in every iteration. I 
believe setting the flags will be effective only the first time when the 
process is spawned.

Has any one else faced a similar problem?

My current schema file for the spawn command looks like this.

debug7 -np 1 -wd /nfs/storage1/users/sudarsar/  worker
debug8 -np 1  -wd /nfs/storage1/users/sudarsar/  worker

debug7 and debug8 are the nodes where I want to spawn new processes 
using the spawn command.  "np" specifies the number of processes to be
spawned on each node. "wd" specifies the working directory. And the last 
argument gives the executable name.

I would really appreciate any kind of help.

Regards,
Rajesh

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