We should consider to enable the flock mount option by default, while still allowing localflock and noflock options for users that do not want this functionality.  From looking at issues reported on http://stackexchange.com/ and others, it seems that the lack of flock functionality by default is an obstacle for many users to use databases on top of Lustre.

If the users are not using flock functionality, I don't think this adds any overhead, and if they are using this functionality then they want it enabled in any case.