Having migrated originally from Civil Engineering, I have always been interested in parallel programming. Quite a few (almost all?) problems in that domain are what can be called embarrassingly parallel - be it Structural Mechanics, Fluid dynamics, or Virtual Modeling.

Recently I got interested in parallel programming again as part of my studies. While the university has a cluster setup, it is almost always in use, and is dead slow because of the number of users. So I tried setting up a simple OpenMP cluster locally for Ubuntu and Solaris,

Setting up OpenMP on Ubuntu is treated in quite a few places in the web, so I am not listing the steps for that. How ever I found that using the cluster tools from Sun was much more easy than messing with the MPICH distribution in Ubuntu.

Here are my notes on getting it to work.

Prerequisites

• You need some machines with the same OS and ARCH, NM
• A common NFS exported directory (mounted on the same path) on each machine. I used /home/myname as the NFS mount
• Ensure that you have password less login either using ssh or rsh.
• You also need to install the cluster tools on each.

You can get the cluster tools from here. Ungzip it to directory and execute the ctinstall binary

$cat sun-hpc-ct-8.1-SunOS-sparc.tar.gz |gzip -dc | tar -xvpf -$ sun-hpc-ct-8.1-SunOS-sparc/Product/Install_Utilities/bin/ctinstall -l
$... This will install the necessary packages. You might need to check the default parameters and verify that they are to your satisfaction.$ /opt/SUNWhpc/HPC8.1/sun/bin/ompi_info --param all all

In my setup, I wanted to use rsh while ssh is the default for clustertools

$/opt/SUNWhpc/HPC8.1/sun/bin/ompi_info --param all all | grep ssh MCA plm: parameter "plm_rsh_agent" (current value: "ssh : rsh", data source: default value, synonyms: pls_rsh_agent) The command used to launch executables on remote nodes (typically either "ssh" or "rsh") MCA filem: parameter "filem_rsh_rsh" (current value: "ssh", data source: default value)$ echo 'plm_rsh_agent = rsh' >> /opt/SUNWhpc/HPC8.1/sun/etc/openmpi-mca-params.conf

Once this is done, create your machines file (my machine names are host1 host2 host3 and host4)

$cat > machines.lst host1 host2 host3 host4 ^D Now you are ready to verify that stuff works. Try$ /opt/SUNWhpc/HPC8.1/sun/bin/mpirun -np 4 -machinefile ./machines.lst hostname
host1
host2
host3
host4

This should also work

$/opt/SUNWhpc/HPC8.1/sun/bin/mpirun -np 4 -host host1,host2,host3,host4 hostname host1 host2 host3 host4 If you get similar output, then you have successfully completed the initial configuration. If you are unable to modify the /opt/SUNWhpc/HPC8.1/sun/etc/openmpi-mca-params.conf file, then you could try the below$ /opt/SUNWhpc/HPC8.1/sun/bin/mpirun -mca pls_rsh_agent rsh -np 4 -machinefile ./machines.lst hostname
host1
host2
host3
host4

Try an example,

$cat hello.c #include <stdio.h> #include <mpi.h> int main(int argc, char **argv) { int my_rank; MPI_Init( &argc, &argv); MPI_Comm_rank(MPI_COMM_WORLD, &my_rank); printf("Hello world[%d] ", my_rank); MPI_Finalize(); return 0; } Try compiling and running$ /opt/SUNWhpc/HPC8.1/sun/bin/mpicc -o hello hello.c
\$ /opt/SUNWhpc/HPC8.1/sun/bin/mpirun -np 4 -machinefile ./machines.lst ./hello
Hello world[2]
Hello world[3]
Hello world[0]
Hello world[1]

Now you are ready to try something larger. You can try with a simple scatter and gather of a matrix that is attached.

(Many thanks to the Sun HPC team for making this setup so easy.)