[MPICH] Using MPI_COMM_SPAWN correctly

[Rajeev Thakur]

Are you using a single MPI_Comm_spawn with maxprocs=4 to spawn the four
process? In that case, I believe they will get spread across the nodes. If
you use four separate MPI_Comm_spawns with maxprocs=1, they will get spawned
on the same node.
 
Rajeev


  _____  

From: owner-mpich-discuss at mcs.anl.gov
[mailto:owner-mpich-discuss at mcs.anl.gov] On Behalf Of Hrant P. Hratchian
Sent: Tuesday, October 24, 2006 11:27 PM
To: mpich-discuss at mcs.anl.gov
Subject: [MPICH] Using MPI_COMM_SPAWN correctly


I'm a basic MPI user and I've built a set of code that uses MPI_COMM_SPAWN.
The way that the code runs the master process runs on only 1 process while
the slave processes use n processes.

I have a mpd.hosts file that includes three machines: node_1, node_2, and
node_3.  mpdtrace confirms that the loop has been established and runs over
all three machines.  To run the code I execute the following on node_1: 

mpiexec -n 1 Prog_Master test.in >& test.mpilog &

Prog_Master spawns 4 processes using MPI_COMM_SPAWN.  Rather than spreading
the 4 spawned processes across the three machines listed in mpd.hosts (where
the loop is running), all 4 spawned processes run on node_1.

Am I doing something wrong here?

Thanks in advance.
HPH

-- 
Hrant P. Hratchian, Ph.D.
E. R. Davidson Fellow 
Department of Chemistry
Indiana University
Bloomington, Indiana 47405-7102
812.856.0829
hhratchi at indiana.edu 

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.mcs.anl.gov/pipermail/mpich-discuss/attachments/20061025/de7a5b6a/attachment.htm>