tests/cpuwaster.c

   1 #undef _DEFAULT_SOURCE
   2 #define _DEFAULT_SOURCE /* for timersub */
   3 #include <sys/time.h>
   4 #include <stdlib.h>
   5 #include <stdio.h>
   6 #include <string.h>
   7
   8 static void gettimestamp(struct timeval* t) {
   9         gettimeofday(t, NULL);
  10 }
  11
  12 static long mspassed(struct timeval* t) {
  13         struct timeval now, diff;
  14         gettimeofday(&now, NULL);
  15         timersub(&now, t, &diff);
  16         return (diff.tv_sec * 1000)  + (diff.tv_usec / 1000);
  17 }
  18
  19 static int syntax() {
  20         puts("prog seconds_of_cpu_time_to_burn");
  21         return 1;
  22 }
  23
  24 long parse_human_number(char* num) {
  25         long ret = 0;
  26         char buf[64];
  27         if(!num) return 0;
  28         size_t l = strlen(num);
  29
  30         if(l && l < sizeof(buf)) {
  31                 if(num[l -1] == 'G')
  32                         ret = 1024 * 1024 * 1024;
  33                 else if(num[l -1] == 'M')
  34                         ret = 1024 * 1024;
  35                 else if(num[l -1] == 'K')
  36                         ret = 1024;
  37                 if(ret) {
  38                         memcpy(buf, num, l);
  39                         buf[l] = 0;
  40                         return atol(buf) * ret;
  41                 }
  42                 return atol(num);
  43         }
  44         return ret;
  45 }
  46
  47 int main(int argc, char** argv) {
  48         void* buf;
  49         long waste_secs;
  50         struct timeval start;
  51         if (argc != 2) return syntax();
  52         waste_secs = parse_human_number(argv[1]);
  53         gettimestamp(&start);
  54
  55         while(mspassed(&start) < waste_secs * 1000) {}
  56
  57         printf("successfully wasted %ld seconds of your cpu time\n", waste_secs);
  58         return 0;
  59 }