Terrible performance between 2.6.16 and 2.6.5

[Frank Steiner <fsteiner-mail1@bio.ifi.lmu.de>]

Hi,

I just upgraded our NFS server from SuSE 9.2 (kernel 2.6.8) to SuSE 10.1
(2.6.16.21). We have some SLES 9 (2.6.5) and some SLES 10 (2.6.16) clients
acessing the NFS server.

When the server ran 2.6.8, the performance was always fine. After upgrading
the SLES 10 clients still have nice performance, but the SLES 9 clients
are terrible.

Here's a test call I'm doing:
  find /mnt/tmp/i586/9/SuSE-updates/ -name \*.rpm -exec rpm -qp {} \;
It just queries all the rpm packages for their name.

When I call this on a SLES 10 client I can monitor the network traffic
on the server lies between 200k and some little peaks at 1.5M.

Calling it on a SLES9 client looks fine at first, then after some RPMs
the network traffic raises to about 20-30 MB/sec! Guess what the server
says when 30 clients search for new RPMs with an algorithm similar to this.

When I call the "find" a second time on the same SLES 9 clients it runs
fine for some longer time, like it had cached the accesses or if it had some
buffer that would fill and then slow the read down.

On all clients we mount with "ro,tcp,hard,rsize=16384,wsize=16384".
Changing sync/async on the server and the clients didn't help.

Are there any known issues? Any ideas how I could debug this? We
can't throw away SLES 9 on these clients, so I need to solve this :-(

cu,
Frank



-- 
Dipl.-Inform. Frank Steiner   Web:  http://www.bio.ifi.lmu.de/~steiner/
Lehrstuhl f. Bioinformatik    Mail: http://www.bio.ifi.lmu.de/~steiner/m/
LMU, Amalienstr. 17           Phone: +49 89 2180-4049
80333 Muenchen, Germany       Fax:   +49 89 2180-99-4049
* Rekursion kann man erst verstehen, wenn man Rekursion verstanden hat. *

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