[OpenMP] Solution 1 : Hello World

This material is part of the course Practical Introduction to Parallel Programming and meant for educational purposes only.

Task

Implement a small OpenMP program that prints the total number of threads and the rank of the current thread.

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Question 1: Hello World

#include <stdio.h>

#ifdef _OPENMP
#include <omp.h>
#else
#define omp_get_num_threads() 1
#define omp_get_max_threads() 1
#define omp_get_thread_num()  0
#endif

int main(int argc, char** argv)
{
    int nthreads, tid;

#pragma omp parallel private(nthreads, tid)
    {
#ifdef _OPENMP
        tid = omp_get_thread_num();
        printf("Thread number = %d\n", tid);

        if (tid == 0)
            {
                nthreads = omp_get_num_threads();
                printf("Number of OpenMP threads = %d\n", nthreads);
            }
#else
        printf("OpenMP support disabled\n");
#endif
    }

    return 0;
}

Question 2: OpenMP environment variables

Specify the OpenMP environment variables that should be used for running your program (mpirun -x OMP_NUM_THREADS=1 -x ...). Use semicolons to separate multiple variables

Question 3: Command Line Argument

Specify the command line arguments that should be passed to your program when it is run. Arguments must be given in quotes and separated by commas. Leave this filed empty if you do not want to specify command line arguments.

Example: "1","int","arg=2" is interpreted as three arguments 1, int, and arg=2.

Author(s)	Erik-Jan Lingen, Matthias Möller
Deadline	Geen deadline
Submission limit	No limitation

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