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



on Sun, Nov 11, 2001 at 11:59:55AM +0100, Eduard Bloch (edi@gmx.de) wrote:
> #include <hallo.h>
> Karsten M. Self wrote on Sat Nov 10, 2001 um 02:48:33PM:
> > > 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.
> 
> Please first how the thing works before adjucating relying on the
> traditional prejuducises (like speed: hash  >> tree >= list). This ist
> not allways true if you know how the client program work. In case of
> ext2, there were allways a problem: when doing file access in a
> directory (readdir), the ext2 driver did allways start at the top of
> the list and searched for that entry. Ext3 stores the position the
> last found entry, so when accessing again, the search begins an this
> position and you get your entry wery fast, in best case within the
> first search loop.

My understanding is that the difference between ext2 and ext3 is the
presence and use of the .journal file.   The issue of list access
remains, and in particular, random file selects, inserts, and deletes,
must operate on the list.

I'd be more convinced of your argument if you'd provide a reference to
ext3 docs describing the behavior you mention.

Peace.

-- 
Karsten M. Self <kmself@ix.netcom.com>       http://kmself.home.netcom.com/
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