start.c 792 B

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  1. #include <stdlib.h>
  2. #include <stdio.h>
  3. #include <sys/time.h>
  4. #define OVERHEAD_TIMES 30000
  5. int main (int argc, char ** argv, char ** envp)
  6. {
  7. struct timeval tv;
  8. gettimeofday(&tv, NULL);
  9. if (argc < 2)
  10. return -1;
  11. unsigned long long msec1 = atoll(argv[1]);
  12. unsigned long long msec2 = tv.tv_sec * 1000000ULL + tv.tv_usec;
  13. struct timeval tv1, tv2;
  14. gettimeofday(&tv1, NULL);
  15. for (int j = 0 ; j < OVERHEAD_TIMES ; j++)
  16. gettimeofday(&tv, NULL);
  17. gettimeofday(&tv2, NULL);
  18. unsigned long long msec3 = tv1.tv_sec * 1000000ULL + tv1.tv_usec;
  19. unsigned long long msec4 = tv2.tv_sec * 1000000ULL + tv2.tv_usec;
  20. unsigned long long overhead = (msec4 - msec3) / OVERHEAD_TIMES;
  21. printf("%llu\n", msec2 - msec1 - overhead);
  22. return 0;
  23. }