ESC23

Your environment needs to be correctly configured in order to compile and run MPI code. The following instructions assume that you are in your home directory on hpc-200-11-40.

$ hostname
hpc-201-11-40.cr.cnaf.infn.it
$ pwd
/home/HPC/studentN

Be sure to have the bash initialization files in your home directory, as recommended when we set up the environment

$ ls .bash_profile .bashrc
.bash_profile .bashrc

Add at the end of .bashrc the loading of the modules compilers/gcc-12.3_sl7 and compilers/openmpi-4-1-5_gcc12.3

echo 'module load compilers/gcc-12.3_sl7 compilers/openmpi-4-1-5_gcc12.3' >> .bashrc

Modify (or create from scratch if not existing) the .ssh/config file so that it contains the following:

$ cat .ssh/config
Host *
  StrictHostKeyChecking no

Exit from the machine and login again. If you open a terminal directly in a VSCode remote connection, disconnect and reconnect again. In both cases be sure to forward the SSH agent. Check that the environment is correct.

$ hostname
hpc-201-11-40.cr.cnaf.infn.it
$ ssh-add -l
3072 SHA256:xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx student30@esc (RSA)
...
$ ssh hpc-200-06-06 pwd
Warning: Permanently added 'hpc-200-06-06,131.154.184.9' (ECDSA) to the list of known hosts.
/storage-hpc/gpfs_data/HPC/home_recovery/student30
...

$ gcc --version
gcc (GCC) 12.3.0
...
$ mpicc --version
gcc (GCC) 12.3.0
...
$ mpirun --version
mpirun (Open MPI) 4.1.5
...

Be sure that when issuing the ssh hpc-200-06-06 pwd command, you don’t need to interact in any way to get the result back.

Examples and exercises are available in the hands-on/mpi directory. Follow the instructions included in the presentation.

Introduction to MPI