How to measure execution time of each thread in openmp?

Question

I'd like to measure the time that each thread spends doing a chunk of code. I'd like to see if my load balancing strategy equally divides chunks among workers. Typically, my code looks like the following:

#pragma omp parallel for schedule(dynamic,chunk) private(i)
for(i=0;i<n;i++){
//loop code here
}

UPDATE I am using openmp 3.1 with gcc

Answer 1

You can just print the per-thread time this way (not tested, not even compiled):

#pragma omp parallel
{
    double wtime = omp_get_wtime();
    #pragma omp for schedule( dynamic, 1 ) nowait
    for ( int i=0; i<n; i++ ) {
        // whatever
    }
    wtime = omp_get_wtime() - wtime;
    printf( "Time taken by thread %d is %f\n", omp_get_thread_num(), wtime );
}

NB the nowaitthan removes the barrier at the end of the for loop, otherwise this wouldn't have any interest.

And of couse, using a proper profiling tool is a way better approach...