The purpose of this programming assignment is to gain experience in parallel programming on a cluster and OpenMP. You will start with a working serial program (quake.c) that models an earthquake, analyze its performance and then add OpenMP directives to create a parallel program.
The goal is to be systematic in figuring out how to parallelize this program. You can use one of three things: manually inserted timers, gprof, or HPCToolkit and/or Hatchet (that you used in Assignment 2) to figure out what parts of the program take the most time. From there you should examine the loops in the most important subroutines and figure out how to add OpenMP directives. The program will be run on a single compute node of the deepthought2 machine.
To compile OpenMP we will be using gcc version 8.4.0 (the default version on deepthought2, which you can get by doing module load gcc on the deepthought2 login node), which nicely has OpenMP support built in. In general, you can compile this assignment with:
gcc -fopenmp -O2 -o quake quake.c -lm
The -fopenmp tells the compiler to, you guessed it, recognize OpenMP directives. -lm is required because our program uses the math library.
The environment variable OMP_NUM_THREADS sets the number of threads (and presumably processors) that will run the program. Set the value of this environment variable in the script you submit the job from. It defaults to using all available cores, and on a deepthought2 node that means 20.
Quake reads its input file from standard input, and produces its output on standard output. Quake generates an output message periodically (every 30 of its simulation time steps), so you should be able to tell if it is making progress.
When the program runs correctly, all versions (serial or parallel) running the
quake.in input, irrespective of the number of threads used, should output this
at the 3840th timestep:
Time step 3840
5903: -3.98e+00 -4.62e+00 -6.76e+00
16745: 2.45e-03 2.66e-02 -1.01e-01
30169 nodes 151173 elems 3855 timesteps
This is the output for quake.in.short:
Time step 30
978: 8.01e-03 7.19e-03 8.41e-03
3394: -3.69e-21 1.57e-20 -5.20e-20
7294 nodes 35025 elems 34 timesteps
You must submit the following files and no other files:
LastName-FirstName-assign3), compress it to .tar.gz (
LastName-FirstName-assign3.tar.gz) and upload that to ELMS.
double start, end; start = omp_get_wtime(); ... work to be timed ... end = omp_get_wtime(); printf("TIME %.5f s\n", end - start);
The project will be graded as follows:
|Runs correctly on 2 threads||20|
|Runs correctly on 8 threads||40|
|Performance with 2 threads||20|
|Performance with 8 threads||10|