I don’t really understand the purpose of what you are asking but this works #include “omp.h” #include <iostream> using namespace std; int main() { #pragma omp parallel { int nthreads = omp_get_num_threads(); for(int i=nthreads-1; i>=0; i–) { #pragma omp barrier { if(i==omp_get_thread_num()) { #pragma omp critical cout << “I am thread “<< i <<endl; } … Read more
You’ve programmed a canonical data-race. All the threads in your program are contending to update the variable count and there are no guarantees about the order in which each thread reads, updates, then writes the values to the variable. Whatever you may believe C++ does not guarantee that ++ is applied atomically. You should read … Read more
You can and probably should amortize the runtime overhead of creating and destroying an OpenMP parallel region by putting all of your parallel constructions – in this case, two do loops and a pair of sections – within a single parallel region. The following code compiles and executes as expected. program main implicit none integer … Read more
Smells like homework and of course the code you pasted wouldn’t even compile, but print #1 – once print #2 & #4 – 4 times, as the block is run once on each CPU “print #” (in the for) – 40 times, if you have 40 CPUs, once on each, if you have 4, then … Read more
I will not do your HW, but I will give a hint. When playing around with OpenMp for loops, you should be alert about the scope of the variables. For example: #pragma omp parallel for for(int x=0; x < width; x++) { for(int y=0; y < height; y++) { finalImage[x][y] = RenderPixel(x,y, &sceneData); } } … Read more