fxp: stalled transfers

[Pyun YongHyeon]

On Fri, Apr 10, 2009 at 08:46:08AM +0200, Bjoern Koenig wrote:
> I wrote:
> >
> >> If you can easily reproduce the issue, can you capture stalled TCP
> >> session with tcpdump on receiving host?(Make sure to disable Rx
> >> checksum offload prior to capturing the session.)
> >
> > I transferred a 256 kiB file and these are the tcpdumps:
> >
> > http://www.alpha-tierchen.de/~bkoenig/fxp0-with-tso.txt
> > http://www.alpha-tierchen.de/~bkoenig/fxp0-without-tso.txt
> >
> > Actually the transfer doesn't stall although ftp and scp told me so. It
> > becomes incredibly slow. It seems like that the chunks are too large and a
> > smaller packet will be resent. I decreased the MTU from 1500 to 1492 and
> > it works fine with TSO enabled.
> >
> > I also captured the traffic on my router:
> >
> > http://www.alpha-tierchen.de/~bkoenig/fxp0-with-tso-router.txt
> > http://www.alpha-tierchen.de/~bkoenig/fxp0-without-tso-router.txt
> >
> > It reveals a suspect information: "truncated-ip - 8 bytes missing!"
> >
> > I almost suppose that this is a PPPoE-related configuration issue and the
> > fxp driver is not necessarily the problem since decreasing the MTU of the
> > LAN host solves it.
> 
> Hello, it's me again. :)
> 
> It's not PPPoE-related. I was able to reproduce the behaviour within a
> regular LAN from host to host. I also have another symptom which denies
> the PPPoE assumption:
> 
> If I set MTU to value X then it doesn't work with MTU X+N anymore. I'll
> get the message "N bytes missing!" in the tcpdump output. For example:
> 
> ifconfig fxp0 mtu 1448   # works
> ifconfig fxp0 mtu 1412   # still works
> ifconfig fxp0 mtu 1448   # doesn't work (36 bytes missing)
> ifconfig fxp0 mtu 1400   # works
> ifconfig fxp0 mtu 1412   # doesn't work (12 bytes missing)
> 

Hmm, I can't reproduce this. Can you send me a URL to captured
data for broken case?