Subject: NFS issues with recent kernels [long]

From: André Berger <[email-masked]>
Date: Fri, 17 Apr 2009 12:27:00 +0200

Hi there!

I'm experiencing NFS [rw]size problems ever since kernel 2.6.18.8,
which allowed for [rw]size=32768. Every kernel 2.16.19-29.6.25.20 (I
tried every single subrevision) gave me only 8K mount results. Before
I come to 2.6.29.1 and my current configuration, let me give you a
short overview.

My system was a Buffalo Linkstation ("LS1"), a PPC model, 

  <http://buffalo.nas-central.org/wiki/Category:LS1>

with Debian etch and its NFS kernel server. The kernels < 2.6.20 were
essentially compiled on a kernel.org or Debian etch basis, plus the
patches from

  <http://www.genbako.com/>

while 2.6.20-2.6.25.20 were compiled from Sylver's

  <http://linkstationwiki.svn.sourceforge.net/viewvc/linkstationwiki/kernel_universal/>

modified sources. Please find all .configs attached.

The clients are Nokia and Sagem dboxII with kernel

  Linux nokia 2.4.32-dbox2 #1 Do Aug 31 20:09:34 CEST 2006 ppc unknown

with 10MBit Half Duplex Ethernet interfaces and Neutrino software, see 

  <http://wiki.tuxbox.org/>

for details.

/etc/exports has never changed,

  /mnt/media/incoming/movies 192.168.1.0/24(rw,async,no_subtree_check,all_squash,anonuid=1000,anongid=1000)

The results vary, depending on the kernel. With 2.6.18, I used to get

  192.168.1.8:/mnt/media/incoming/movies on /var/autofs/record type nfs (rw,v3,rsize=32768,wsize=32768,soft,udp,nolock,addr=192.168.1.8)

  etc., for both TCP and UDP, on both dbox models.

While I got only 8K with my LS1, my HG 

  <http://buffalo.nas-central.org/wiki/Category:HG>

with 2.6.25.20 and 2.6.29.1 gives me 16K, but still not 32K. The
numbers are related to the performance, 8K mounts make it impossible
for me to use the LS as a VCR. 16K mounts seem to be better, but
haven't been stress-tested yet here, as Cable TV bitrates vary.

After an upgrade from Buffalo's bootloader in FLash ROM to uboot, I
have been unable to boot non-flat device tree kernels like 2.6.18,
and switched from the LS1 to the HG model in the troubleshooting
process. As the latests kernels still don't reach 32K on that system
either, I suspect a bug.

For the sake of completeness, my router is a Linksys WRT54G 

with Tomato firmware

  <http://www.polarcloud.com/tomato_123>

and a MTU of 1492 throughout the network.

If there is anything I can do to help troubleshooting, please let me
know.

Thank you for reading!

-André

-- 
May as well be hung for a sheep as a lamb!
Linkstation/KuroBox/HG/HS/Tera Kernel 2.6/PPC from <http://hvkls.dyndns.org>
iPhone <http://hvkls.dyndns.org/downloads/documentation/README-iphone.html>