[Linux-cluster] locking granularity of GFS?
Michael Conrad Tadpol Tilstra
mtilstra at redhat.com
Fri Jun 3 13:01:46 UTC 2005
On Thu, Jun 02, 2005 at 05:34:44PM -0400, Dan B. Phung wrote:
> What is the current locking granularity of GFS? I found an IBM GPFS
> report that stated the GFS uses a global lock, which is entirely false
> since I know GFS uses DLM.
>
> From what I've seen from use, my guess is that it's at the directory
> level, which seems wierd. Writing to different files in the same
> directory gives sequential finishing times. when I modified the output to
> go to different directories, this change alleviated the finishing times
> disparity.
GFS has a couple pf locks for each file. (one for data, one for meta
data, one for iopen counts. maybe others, don't recall off the top of my
head.) Directories get a lock, as well as most of the interal
structures. So more-or-less gfs locks at the file level. (note that
this is not the same or similar to fcntl locking, nor is it compatible.)
--
Michael Conrad Tadpol Tilstra
I can read your mind, and you should be ashamed of yourself.
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