pt-variable-advisor suggests innodb_flush_method O_DIRECT even when ALL_O_DIRECT is specified

mysql> show global variables like 'innodb_flush_method';
+---------------------+--------------+
| Variable_name | Value |
+---------------------+--------------+
| innodb_flush_method | ALL_O_DIRECT |
+---------------------+--------------+
1 row in set (0.00 sec)

%> ./pt-variable-advisor localhost
...
# NOTE innodb_flush_method: Most production database servers that use InnoDB should set innodb_flush_method to O_DIRECT to avoid double-buffering, unless the I/O system is very low performance.
...

That should be covered by ALL_O_DIRECT