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[Arlie Stephens]

On Jul 25 2014, Nick Krause wrote:
> > But if nothing like that is jumping out at you, maybe you should go look
> > around and see if there's something in userspace that *does* jump out at you.
> 
> I am interested in file systems and will be working on brtfs and ext4.
> Cheers Nick

If you want an annoying problem, explain and/or fix directory
performance on ext4. I've got a server where an ls of a directory took
5 seconds, according to "time", even though it only has 295 entries at
present.

It's a rather large directory, 4 times the size of a normal directory
in the opinion of ls -ld, and filefrag reports it has 7 extents. 

I'm also getting anecdotal reports of rename() taking unreasonable
amounts of time, probably with at least one of the directories
involved being in a similar state.  (They would have been created and
populated by the same software.) 

Probably the directory had a large number of files and/or
subdirectories some time in the past, and this is "expected
behaviour".  Expected or not, it seems to me that it's about time that 
linux handles directories with something closer to the efficiency with 
which it handles files ;-) 

-- 
Arlie

(Arlie Stephens					arlie at worldash.org)