Project 1, CS621, Fall 2009

CS621: Fall 2009

Project 1: (Due on October 6, 2009, 2:00PM) Experiencing MPI

This project helps you gain some experience by setting up an MPI environment and running some sample MPI programs on your own computer.

You can learn about MPI programming from the class notes, "Programming Using Message-Passing" and Tutorial on MPI: The Message Passing Interface.

You may begin by compiling and running a sample program. In order to run this sample program you must:

Visit http://www-unix.mcs.anl.gov/mpi/mpich2/ to download a copy of the MPI software to install on your own computer.
- Read the manual to see how the MPI environment can be installed on your computer.
Download the following files.
- Sample C and Sample Fortran programs
You can compile the files explicitly.
- type: mpicc -lm cpi.c , for C program
- type: mpif90 pi3.f, for Fortran program
To run these programs.
- Specifying number of processes :
  mpirun -np 3 executable-file.

Once you got your program running, you should do the following exercises to get a feeling of parallel computing. (20 points)

Add an MPI function to compute and print out the time elapsed between the computations (see Tutorial on MPI: The Message-Passing Interface).
Choose the number of nodes (intervals) to be a large number, say, 2,000,000 and run the program by specifying 1, 2, 4, 8, 16, 32 etc. processes and record the elapsed time.
Choose the number of nodes (intervals) to be a smaller number, say, 200, and repeat the above procedure.
Graph the relation between the number of processes and the timings.
Modify the code so that you will not use MPI_Reduce to collect the final result. Instead, ask each process to send its local sum to the process 0, which will compute the final sum and output the result.
Submit a print-out of your code, two graphs showing the above tests, and a short explanation on the results you obtained.