Thread: Parallel processing

It doesn't do anything automatically for you. You have to make sure the code contains OpenMP directives and such. There should be tutorials...
And OpenMP is completely integrated in VS, so no need for anything extra.

You may also be thrilled to know that Visual Studio 2010 will ship with parallel processing libraries / stuff.

If you would follow the example and set the number of cores you want, it should work. Theoretically anyway.
It may be some other unknown factor at work, like race conditions and stuff. OpenMP does not protected you against that.

You do have to turn on OpenMP support in Visual Studio or your #pragma omp directives will be ignored by the compiler. That would explain why you only had 1 thread inside your parallel block. For more information on OpenMP and Visual Studio, see MSDN.

Code:

Could be that the program I have the plugin for is not liking OpenMP for some reason.

OpenMP has nothing special by itself. The preprocessor use the directives to add code to your code to make it multithreaded. But with the information I have, I couldn't tell why your program is crashing at runtime.

Is it possible with OpenMP to explicitly set one processor to run one function and another to do something different at the same time?

Yes, look at the sections directive to achieve task parallelism.

Example code... web resources, tutorials?

I've just started learning parallel processing and IMHO, there just isn't too much useful info on the net concerning parallel processing in general and OpenMP in particular. I did find one useful example as follows:

Code:

// openmp.cpp : Defines the entry point for the console application.
//
#include <stdio.h>
#include <time.h>
#include <float.h>
#include <math.h>
#include <windows.h>
#ifdef _OPENMP
#include <omp.h>
#endif
#define BOOL _Bool
#define true 1
#define false 0

// Matrix size constants
// Be careful to set your shell's stacksize limit to a high value if you
// wish to increase the SIZE.
#define SIZE 160 // Must be a multiple of 8.
#define M SIZE/8
#define N SIZE/4
#define P SIZE/2
#define NTIMES 5 // product matrix calculations

int main(void)
{
    double a[M][N], b[N][P], c[M][P], walltime;
    printf("here\n");

    bool nthr_checked=FALSE;
    time_t start;

    int i, j, k, l, i1, i2, i3, k1, k2, k3, nthr=1;

    printf("Using time() for wall clock time\n");
    printf("Problem size: c(%d,%d) = a(%d,%d) * b(%d,%d)\n",
        M, P, M, N, N, P);
    printf("Calculating product %d time(s)\n", NTIMES);

    // a is identity matrix
    for (i=0; i<M; i++)
        for (j=0; j<N; j++)
            a[i][j] = 1.0;

    // each column of b is the sequence 1,2,...,N
    for (i=0; i<N; i++)
        for (j=0; j<P; j++)
            b[i][j] = i+1.;

    start = time(NULL);

#ifdef _OPENMP
#pragma omp parallel private(i,j,k)
#endif
    {
        for (l=0; l<NTIMES; l++) {
#ifdef _OPENMP
#pragma omp single nowait
#endif
            if (!nthr_checked) {
#ifdef _OPENMP
                nthr = omp_get_num_threads();
#endif
                printf( "\nWe are using %d thread(s)\n", nthr);
                nthr_checked = true;
            }

            // Initialize product matrix
#ifdef _OPENMP
#pragma omp for nowait
#endif
            for (i=0; i<M; i++)
                for (j=0; j<P; j++)
                    c[i][j] = 0.0;

            // Parallelize by row. The threads don't need to synchronize at
            // loop end, so "nowait" can be used.
#ifdef _OPENMP
#pragma omp for nowait
#endif
            for (i=0; i<M; i++) {
                for (k=0; k<N; k++) {
                    // Each element of the product is just the sum 1+2+...+n
                    for (j=0; j<P; j++) {
                        c[i][j] += a[i][k] * b[k][j];
                    }
                }
            }
        } // #pragma omp parallel private(i,j,k)
    } // l=0,...NTIMES-1

    walltime = time(NULL) - start;
    printf("\nFinished calculations.\n");
    printf("Matmul kernel wall clock time = %.2f sec\n", walltime);
    printf("Wall clock time/thread = %.2f sec\n", walltime/nthr);
    printf("MFlops = %f\n",
        (double)(NTIMES)*(double)(N*M*2)*(double)(P)/walltime/1.0e6);

    return 0;
}

I'm not sure where I found the above example. But IMHO, it's a good starting point to learn OpenMP.

Also, the best tutorials I have found so far are located at high performance computing link. I use the training material provided for the introduction to parallel processing and OpenMP. I'll be using this resource until I find something better.

Finally, the last time I checked, the MS Express edition compiler doesn't support parallel processing. You'll need the Professional edition or higher.

You need to indent any code you post.