Date:	Fri, 17 Apr 2009 12:29:23 -0400
From:	Chuck Lever <chuck.lever@...cle.com>
To:	André Berger <andre.berger@....de>
Cc:	Guennadi Liakhovetski <g.liakhovetski@....de>,
	Linux NFS Mailing List <linux-nfs@...r.kernel.org>,
	netdev@...r.kernel.org
Subject: Re: NFS issues with recent kernels [long]

Copying linux-nfs@...r.kernel.org, please follow up there.

On Apr 17, 2009, at 6:27 AM, André Berger wrote:

> 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.

To summarize, you are running late model 2.6 kernels on a NAS  
appliance, and your 2.4 clients are having trouble using large rsize  
and wsize.

> 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.

Even with NFS/TCP ?  Oh, I see -- the clients are 10Mbit half-duplex.

> 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.

Any relevant messages in the kernel log on either the client or server?

You could try capturing a raw packet trace of the initial mount and a  
few reads and write on the share.  The clients negotiate the rsize and  
wsize settings with the server, and the packet dump would expose the  
negotiated values.

On your clients, use "tcpdump -s 0 -w /tmp/raw host" followed by the  
DNS name of your server.  Then attach the raw pcap files to e-mail (as  
long as they are less than 100KB or so) and post them to linux-nfs@...r.kernel.org 
.

> 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.

--
Chuck Lever
chuck[dot]lever[at]oracle[dot]com--
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