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Re: So: reiserfs or ext3 (was Re: ext3 to be in 2.4.15!)



on Sat, Nov 10, 2001 at 08:12:09PM -0200, Jeronimo Pellegrini (pellegrini@mpcnet.com.br) wrote:
> On Sat, Nov 10, 2001 at 02:03:10PM -0800, Karsten M. Self wrote:
> > I've got both ext3fs and reiserfs on my most recent laptop build.
> > 
> > There are advantages to each.
> > 
> > Reiserfs has better performance with larger filesystems, particularly
> > for large directory listings.  In one case, I've got a directory with
> > 125,000 files in it.  Under ext*, directory operations are very slow, on
> > the order of several seconds, due to the need to scan a file list.
> > Reiserfs's use of a hash to store directory entries makes manipulation
> > far faster.
> > 
> > OTOH, ext3fs has far less disk overhead for small partitions.  Word is
> > that the reiserfs journal requires 32MB, regardless of partition size,
> > while ext3's .journal file is sized proportionately.
> 
> Now that you said this... I'd like to see how reiserfs and
> ext3 in writeback mode perform. I'd think ext3 would still be
> outperformed by reiser for the large dir listings.

The issue isn't writing the directories, but searching them.  Hash beats
linear scan, above the hash overhead threshhold.  This crossover's
clearly evident for 10,000 directory entries, and is probably
significant at substantially fewer.

-- 
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