NFS dropouts with <=2.4.15pre1 + ReiserFS

[Jens Benecke <jens@jensbenecke.de>]

Hi,

both to linux-kernel and reiserfs-list because currently I don't know who
to blame. It should be related to ReiserFS + NFS however, because I can FTP
between the systems and get 8-9MByte/sec.

I have two machines, ds9 (workstation) and server (well..), running
2.4.15pre1. The server was patched with grsecurity (www.grsecurity.net),
the workstation was patched with Win4lin (commercial, www.netraverse.com).

As I said, FTP works fine. But when I copy something via NFS, performance
is about a third to a fifth of the FTP performance - AND, from time to time
(I'd say every 200-300MByte) NFS throughput drops out completely.

I turned on NFSd debugging and got lots and lots of "fh_verify",
"fh_compose" etc messages in the kernel and found something very curious:

	Whenever my iptables packet filter would log denied packets, NFS
	would drop out for a couple seconds to a couple minutes - then
	resume operations. My NFS client told me "nfs server not
	responding, NFS server OK" a couple times.

This seems reproducable with a little effort - so I'd be happy to help
debugging this (and the bad performance ;) if anybody tells me where to
start. As I said, with 'echo 9 > nfsd_debug' I got megabytes of logs filled
with nfsd_dispatch, fh_verify, fh_compose, last message repeated 295 times,
etc. but nothing that (for me) pointed to an error situation.

The same happened with all 2.4 kernels I tried so far, as far as I can
remember.

Thanks in advance!


-- 
Jens Benecke ········ http://www.hitchhikers.de/ - Europas Mitfahrzentrale