Introduction to Using MPI at The School of Computational Science and the Shared HPC

**Welcome to Team HPC and TSG's tutorial on MPI**

These slides and codes are meant to give you a simple but non-trivial introduction to computing in parallel using MPI on our shared HPC center and how to submit jobs through the batching system MOAB.

The slides for the workshop may be downloaded here, Intro to MPI on the shared HPC at FSU.

The C codes for the tutorial may be downloaded here,

• mpiHello1.cc First Hello World program in C, no control over processes.
• mpiHello2.cc Second Hello World program in C, implementing control over processes.
• Int1_mpi.cc First numerical integration program in C, sends and recieves only.
• Int2_mpi.cc Second numerical integration program in C, using MPI_Reduce.

The MOAB scripts may be downloaded here,

• moab.Hello1.sh First Hello World batch script,
• moab.Hello2.sh Second Hello World batch script,
• moab.Int1.sh First numerical integration batch script,
• moab.Int2.sh Second numerical integration batch script,

Fortran90 versions of the C codes for the tutorial may be downloaded here,

• Hello_mpi.f90Hello World program in Fortran90,
• intervals_mpi.f90 First numerical integration program in Fortran90, sends and recieves only.
• Quadrature_mpi.f90 Second numerical integration program in Fortran90, using MPI_Reduce.

The whole set of codes and slides can all be downloaded in the following tar file, mpi_at_hpc.tgz. To extract the files, put the tar file into your directory and type, tar -xvzf mpi_at_hpc.tgz

**A more detailed look at the performance of the different types of sends and receives that can be used in MPI codes**

The example problem used to illustrate the different uses of the sends and receives in the MPI standard is a 1-dimensional domain decomposition of the 2D linear Poisson equation, a classic eliptic partial differential equation. Domain decomposition is an explicit parallelization of the spatial domain and can be used in many settings including time dependent or time evolution problems such as heat flow, fluid flow, and wave propogation. A paper that I wrote reporting the results can be downloaded here, Domain Decomposition of the Poisson Problem using MPI.

The whole set of codes and the report can all be downloaded in the following zipped tar file, DomainDecomp_Poisson_Codes. To extract the files, put the tar file into your directory and type, tar -xvzf poisson_dd.tgz

All of the code for this problem is written in Fortran90 and thus is fairly easy to understand by examing the actual source code which is why it is being made available. Cooperation is greater than competition which is why I don't mind sharing my source code that I worked very hard on, so please enjoy.

Author: Chris Harden