* don't need the rest. */
_madvise(data, _page_size, MADV_WILLNEED | MADV_SEQUENTIAL);
_madvise(data + _page_size, (rrd_file->file_len >= _page_size)
? rrd_file->file_len - _page_size : 0, MADV_DONTNEED);
* don't need the rest. */
_madvise(data, _page_size, MADV_WILLNEED | MADV_SEQUENTIAL);
_madvise(data + _page_size, (rrd_file->file_len >= _page_size)
? rrd_file->file_len - _page_size : 0, MADV_DONTNEED);