joerg@Marvin:~> perl -E'
    my $buf = "";
    {
        open my $fh, ">", \$buf;
        utf8::encode( my $all_256_bytes = join "", map chr, 0..255 );
        say length $all_256_bytes;
        say do { use bytes; length $all_256_bytes };
        print $fh $all_256_bytes;
    }
    say length($buf);
'
384
384
384