[Cooker] Dramatic poor performance for XFS delete (worse since 2008.1)

[Olivier LAHAYE]

Recetly, I've discovered that XFS delete performance have been worse than 
ever.
Doing the test below on ext3 and on xfs (same partition, same computer (after 
a mkfs) shows that ext3 is using buffers (disk blinks from times to  times) 
while xfs seems to write the disk on the fly (disk always lit).

Question: are you aware of a patch in kernel that (for any reason) disabled 
the use of buffers in XFS?

time ( for i in $(seq 1 10000); do echo $i | md5sum> xxx_$i; done; sync ); 
time ( /bin/rm -f xxx_*; sync )

Note that we studied disk parameters and set the same in both tests 
(hdparm -c3 -d1 -u1)
and I mountex xfs filesystem using -ologbufs=8

With absolutely no differences.

Following the tweaking guide below did not change any results (while some 
improvements were expected)
http://www.generation-nt.com/licence-3g-rejet-candidature-free-mobile-arcep-actualite-46044.html

This leads me to think that now, the xfs filesystem doesn't use any buffer 
I/O. Am I wrong?

-- 
	Olivier LAHAYE
	Motorola Labs IT Manager
	Computer & Information Systems
	European Communications Research