timethese(-6, {
        'sum' => sub {
            my $n = sum
                    map $_->{count},
                    map { values %{ $_->{tool} } } @drill_arr;
        },

        'sub' => sub {
            my $n = &{ sub {
                my $ret;
                foreach my $l ( @drill_arr ) {
                    foreach ( values %{$l->{tool}} ) {
                        $ret += $_->{count};
                    }
                }
                return $ret;
            } };
        },
    });