tvdiff
tvdiff(&end, &start));
printf("(linear search took %ju usecs)\n", tvdiff(&end, &start));
tvdiff(&end, &start));
tvdiff(&end, &start));
struct timeval tvthen, tvnow, tvdiff;
timersub(&tvnow, &tvthen, &tvdiff);
if (tvdiff.tv_sec > 0)
usleep(1000000 - tvdiff.tv_usec);