80 lines
1.5 KiB
C
80 lines
1.5 KiB
C
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <math.h>
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#include "omp.h"
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#include "aux.h"
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int sequential_reduction(int *x, int n);
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int parallel_reduction(int *x, int n);
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int main(int argc, char **argv)
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{
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int n, i, result;
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long t_start, t_end;
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int *x;
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// Command line argument: array length
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if (argc == 2)
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{
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n = atoi(argv[1]); /* the length of the pref */
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}
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else
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{
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printf("Usage:\n\n ./main n\n\nwhere n is the length of the array to be used.\n");
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return 1;
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}
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x = (int *)malloc(sizeof(int) * n);
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/* Fill the array with random numbers */
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srand(1);
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for (i = 0; i < n; i++)
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x[i] = rand() % n;
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/* Sequential reduction */
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t_start = usecs();
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result = sequential_reduction(x, n);
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t_end = usecs();
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printf("Sequential time : %8.2f msec. --- Result: %d\n", ((double)t_end - t_start) / 1000.0, result);
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/* Fill the array with random numbers */
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srand(1);
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for (i = 0; i < n; i++)
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x[i] = rand() % n;
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/* Parallel reduction */
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t_start = usecs();
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result = parallel_reduction(x, n);
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t_end = usecs();
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printf("Parallel time : %8.2f msec. --- Result: %d\n", ((double)t_end - t_start) / 1000.0, result);
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return 0;
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}
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int sequential_reduction(int *x, int n)
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{
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int i;
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for (i = 1; i < n; i++)
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operator(x, x + i);
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return x[0];
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}
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int parallel_reduction(int *x, int n)
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{
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int i;
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int red = 0;
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#pragma omp parallel
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#pragma omp for reduction(+ : red)
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for (i = 0; i < n; i++)
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{
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operator(&red, x + i);
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}
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return red;
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}
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