parallel.c

#include <stdlib.h>
#include <stdio.h>
#include <sys/time.h>
#include <cilk/cilk.h>

#define n 4096
int s = 4;
double A[n][n];
double B[n][n];
double C[n][n];

float tdiff(struct timeval*start, struct timeval*end){
              return (end->tv_sec-start->tv_sec)
              +1e-6*(end->tv_usec-start->tv_usec);
            }

int main(int argc, const char *argv[]){
  for(int i = 0; i < n; ++i){
    for(int j = 0; j < n; ++j){
      A[i][j] = (double)rand() / (double)RAND_MAX;
      B[i][j] = (double)rand() / (double)RAND_MAX;
      C[i][j] = 0;
    }
  }
struct timeval start, end;
gettimeofday(&start, NULL);

cilk_for(int ih=0; ih<n; ih +=s){
  cilk_for(int jh=0; jh<n; jh +=s){
    for(int kh=0; kh<n; kh +=s){
      for(int il=0; il<s; ++il){
        for(int kl=0; kl<s; ++kl){
          for(int jl=0; jl<s; ++jl){
            C[ih+il][jh+jl] += A[ih+il][kh+kl] + B[kh+kl][jh+jl];
          }
        }
      }
    }
  }
}
gettimeofday(&end, NULL);

printf ("%0.6f\n", tdiff(&start, &end));
return 0;

}