OpenACC test code

openacc_test.c

/**
 *  A test code to test whether PGI compiler is successfully installed and configured
 *  for openacc code.
 *
 *  Origin: https://www.olcf.ornl.gov/tutorials/openacc-vector-addition/
 *  
 *  Minor changes to print out information when data initialization on host is done
 *  Compile the code with command line: `pgcc -Minfo -ta=tesla openacc_test.c -o test.out`
 */
#include <stdio.h>
#include <stdlib.h>
#include <math.h>
 
int main( int argc, char* argv[] )
{
 
    // Size of vectors
    //int n = 1000000000;
    int n = 100000000;
 
    // Input vectors
    double *restrict a;
    double *restrict b;
    // Output vector
    double *restrict c;
 
    // Size, in bytes, of each vector
    size_t bytes = n*sizeof(double);
 
    // Allocate memory for each vector
    a = (double*)malloc(bytes);
    b = (double*)malloc(bytes);
    c = (double*)malloc(bytes);
 
    // Initialize content of input vectors, vector a[i] = sin(i)^2 vector b[i] = cos(i)^2
    int i;
    for(i=0; i<n; i++) {
        a[i] = sin(i)*sin(i);
        b[i] = cos(i)*cos(i);
    }  
    printf("Done initialization!\n");
 
    // sum component wise and save result into vector c
    #pragma acc kernels copyin(a[0:n],b[0:n]), copyout(c[0:n])
    for(i=0; i<n; i++) {
        c[i] = a[i] + b[i];
    }
 
    // Sum up vector c and print result divided by n, this should equal 1 within error
    double sum = 0.0;
    for(i=0; i<n; i++) {
        sum += c[i];
    }
    sum = sum/n;
    printf("final result: %f\n", sum);
 
    // Release memory
    free(a);
    free(b);
    free(c);
 
    return 0;
}