with dir_index ls is slower than without?

Sebastian Reitenbach sebastia at l00-bugdead-prods.de
Mon Mar 31 11:18:06 UTC 2008

Hi Nicolas,

Nicolas KOWALSKI <niko at petole.dyndns.org> wrote: 
> "Sebastian Reitenbach" <sebastia at l00-bugdead-prods.de> writes:
> > installhost2:~ # time ls -la /mnt/index/ | wc -l
> >  500005
> >  
> >  real 2m41.015s
> >  user 0m4.568s
> >  sys 0m6.520s
> >  
> >  
> >  installhost2:~ # time ls -la /mnt/noindex/ | wc -l
> >  500005
> >  
> >  real 0m10.792s
> >  user 0m3.172s
> >  sys 0m6.000s
> >
> > I expected the dir_index should speedup this a little bit?
> > I assume I'm still missing sth?
> I think the point of dir_index is "only" to quickly find in a large
> directory a file when you _already_ have its name.
> The performance of listing is not its purpose, and as you noted it,
> even makes performance worse.

ah, that would explain what I've seen here. 

after reading your answer, I found this older mail in the archives:

So everything seems to depend on how the application is using the
Picking a single given file might be faster than with a plain ext3, but 
scanning and opening all files in a directory might become slower. I wanted 
to use the dir_index for some partitions, like for cyrus imap server, and 
for some other applications. I think I have to benchmark the applications, 
to see whether they get a speed gain of the dir_index or not.

kind regards

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