rem: return (t2->tv_sec - t1->tv_sec) * 1000
add: return (t2->tv_sec - t1->tv_sec) * 1000L
context: static unsigned long msdiff(struct timeval *t1, struct timeval *t2){	return (t2->tv_sec - t1->tv_sec) * 1000	     + (t2->tv_usec - t1->tv_usec) / 1000;}