rem: select(0, NULL, NULL, NULL, tv);
add: select(0, NULL, NULL, NULL, &tv);
context: static void sleep_for_bwlimit(int bytes_written){	struct timeval tv;	if (!bwlimit)		return;	assert(bytes_written > 0);	assert(bwlimit > 0);		tv.tv_usec = bytes_written * 1000 / bwlimit;	tv.tv_sec  = tv.tv_usec / 1000000;	tv.tv_usec = tv.tv_usec % 1000000;	select(0, NULL, NULL, NULL, tv);}