RE: xen.git branch reorg

["Venefax" <venefax@gmail.com>]

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What are the exact commands to turn off Segmentation Offload and Checksum
Offload?

Also, should this be done only at Dom0 or also at DomU's?

Is this correct or should it be "eth0"?

 

/usr/local/sbin/ethtool -K etho tx off

F.Alves

From: xen-devel-bounces@lists.xensource.com
[mailto:xen-devel-bounces@lists.xensource.com] On Behalf Of Boris Derzhavets
Sent: Saturday, April 25, 2009 2:55 AM
To: Jeremy Fitzhardinge; Christophe Saout
Cc: Xen-devel; Ian Campbell
Subject: Re: [Xen-devel] xen.git branch reorg

 


Chris,

I have to apologize. Turning off segmentation offloading may work as well.
Just now it fixed VNC issue on bare metal - CentOS 5.2 with Atansic Gigabit
Ethernet driver (ASUS P5KR) . I gonna try it at DomUs at my earliest
convenience.

Boris.

--- On Fri, 4/24/09, Christophe Saout <christophe@saout.de> wrote:

From: Christophe Saout <christophe@saout.de>
Subject: Re: [Xen-devel] xen.git branch reorg
To: "Jeremy Fitzhardinge" <jeremy@goop.org>
Cc: bderzhavets@yahoo.com, "Xen-devel" <xen-devel@lists.xensource.com>, "Ian
Campbell" <Ian.Campbell@citrix.com>
Date: Friday, April 24, 2009, 6:39 PM

Hi Jeremy,


  


> >  In meantime time i see,  that
 2.6.30-rc3&rc2&rc1-tip are


affected.


> > Solution is the same as on Solaris xVM Linux DomUs about one


> > year ago -  is  to disable checksum (nothing else) offloading at


Linux 


> > DomUs ( CentOS 5.3, Ubuntu 9.04)


> >


> > /usr/local/sbin/ethtool -K etho tx off


>


> OK, that's a good lead.


  


Yes, I've been seeing this too (and meant to investigate it before


claiming there's abug) and I can confirm that turning off segmentation


offloading "cures" the problem here too.


  


Now the tcpdump on Dom0 looks interesting.  It repeatedly sees a packet


with 2880 byte from DomU coming in, which is then dropped and ICMP


"fragmentation needed" sent back, the DomU resends a 1440 byte packet


(after some delay), which then goes through, but then the next one is a


2880 byte one again, and so on.


  


FYI: My Dom0 is running NAT, in case this is relevant.


  


  


  
        Christophe


  


  


  


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