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comparison twice.c @ 0:b8c472c04dc9

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Add twice.c
author innparusu
date Sat, 03 Feb 2018 23:34:56 +0900
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-1:000000000000 0:b8c472c04dc9
1 #include <stdio.h>
2 #include <string.h>
3 #include <stdlib.h>
4 #include <omp.h>
5 #include <sys/time.h>
6
7 int length = 1024;
8 int cpu_num = 1;
9 void init(int argc, const char* argv[]) {
10 for (int i = 1; argv[i]; ++i) {
11 if (strcmp(argv[i], "-cpu") == 0)
12 cpu_num = (int)atoi(argv[i+1]);
13 else if (strcmp(argv[i], "-l") == 0)
14 length = (int)atoi(argv[i+1]);
15 }
16 }
17
18 int main(int argc, const char* argv[])
19 {
20 int n;
21 init(argc, argv);
22 omp_set_num_threads(cpu_num);
23 int *a;
24 a = (int *) malloc(sizeof(int) * length);
25 for (int i = 0; i < length; i++)
26 {
27 a[i] = i;
28 }
29
30 struct timeval tv;
31 gettimeofday(&tv, NULL);
32 double now = tv.tv_sec + (double)tv.tv_usec*1e-6;
33
34 #pragma omp parallel for
35 for(int i = 0; i < length; i++)
36 {
37 a[i] = a[i] * 2;
38 }
39
40 gettimeofday(&tv, NULL);
41 printf("%0.6f\n", (tv.tv_sec+(double)tv.tv_usec*1e-6) - now);
42
43 for(int i = 0; i < length; i++)
44 {
45 if(a[i] != i*2) {
46 printf("fail\n");
47 }
48 }
49
50 return 0;
51 }