[lustre-devel] Lock ahead - Possible change
Patrick Farrell
paf at cray.com
Fri Jul 10 09:14:45 PDT 2015
Good morning,
I am reluctant to make further changes to lock ahead at this point when
it is ready and pending review, but I wanted to float an idea to see if
it would likely meet acceptance. (I am primarily asking Jinshan and
Andreas, who have been involved from the beginning.)
Currently, lock ahead requests are asynchronous, and, because of that,
non-blocking. What about the possibility of also allowing blocking,
*synchronous* requests via the same API?
This is intended as a way for a client to make a blocking lock request
on a specific region of a file, rather than the whole file by taking a
group lock as is currently the only option.
This would not be used for my immediate goal of enhancing strided
writing performance with lock ahead itself, but might be handy in other
situations and is a pretty minor change to the API. (Just allow
blocking requests and make them synchronous, rather than not allowing
them as is the case now.)
I still think I will push this out to a future enhancement of the
feature rather than integrate it into the current patch.
Thoughts? Objections?
I admit that this expansion of the API is making me question 'lock
ahead' as the name for the API itself, rather than a particular usage of
it. Perhaps that's not a direction we want to go, or perhaps we should
rename the API. (Suggestions encouraged)
- Patrick Farrell
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