From mboxrd@z Thu Jan 1 00:00:00 1970 From: Boris Derzhavets Subject: Re: xen.git branch reorg Date: Fri, 24 Apr 2009 23:55:19 -0700 (PDT) Message-ID: <724403.69764.qm@web56102.mail.re3.yahoo.com> References: <1240612762.1918.5.camel@leto.intern.saout.de> Reply-To: bderzhavets@yahoo.com Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="===============0359383568==" Return-path: In-Reply-To: <1240612762.1918.5.camel@leto.intern.saout.de> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xensource.com Errors-To: xen-devel-bounces@lists.xensource.com To: Jeremy Fitzhardinge , Christophe Saout Cc: Xen-devel , Ian Campbell List-Id: xen-devel@lists.xenproject.org --===============0359383568== Content-Type: multipart/alternative; boundary="0-92678410-1240642519=:69764" --0-92678410-1240642519=:69764 Content-Type: text/plain; charset=us-ascii 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 wrote: From: Christophe Saout Subject: Re: [Xen-devel] xen.git branch reorg To: "Jeremy Fitzhardinge" Cc: bderzhavets@yahoo.com, "Xen-devel" , "Ian Campbell" 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 _______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel --0-92678410-1240642519=:69764 Content-Type: text/html; charset=us-ascii
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 Camp bell" <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), w
 hich 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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