Re: [forums] RE: [Xen-users] Re: domU network fails under load - vif breaks

[Paul <xensource@xxxxxxxxxxx>]

Hi Nathan,

Yeah, this was something I was wondering about too...  The driver change 
was from the kernel driver to the manufacturers own driver - but I 
imagine it leverages off code in the kernel in any case.
I am testing a tulip based 10/100 card at the moment, and pushing it 
pretty hard without any issues.  This isn't a one for one test yet, as I 
have my other domains off the original nic, but it certainly looks 
promising.
Paul


Nathan Eisenberg wrote:
> Paul,
>
> I'm wondering if #3 is a large enough change to rule out driver issues.  Maybe try an entirely different chipset and manufacturer - perhaps an Intel, Broadcom, etc NIC.  
>
> Thank you,
> Nathan Eisenberg
> Sr. Systems Administrator
> Atlas Networks, LLC
>
>
> -----Original Message-----
> From: xen-users-bounces@xxxxxxxxxxxxxxxxxxx 
> [mailto:xen-users-bounces@xxxxxxxxxxxxxxxxxxx] On Behalf Of Paul
> Sent: Thursday, September 04, 2008 3:43 PM
> Cc: xen-users@xxxxxxxxxxxxxxxxxxx
> Subject: [Xen-users] Re: domU network fails under load - vif breaks
>
>   
> > On Sep 1, 2008, at 8:57 AM, Paul wrote:
> >
> >   
> >
> >     At a certain point that I have not established exactly, the
> >     network load takes out the pv network. For example, if I initiate
> >     a bittorrent session in a pv domU, I get a slow build up of
> >     network load, and then connectivity is lost to both of the pv
> >     domU's. If I console into them, they cannot ping outside the
> >     network, but they can ping their own interfaces. A tcpdump on the
> >     dom0 physical shows no traffic. However, during all this, the hvm
> >     domains are able to use their network connections without issues. 
> >
> > I have experienced the same issue with Ubuntu 8.04. The only solution 
> > I have found is to limit the rate of the nic so that it doesn't reach 
> > a transfer rate that breaks the networking.
> > Pepe
> >   
> >     
> Thanks Pepe.  My last test showed the network breaking at 3.6Mbs  - too 
> slow to lower the nic rate, and having networking running that slow 
> would make the vm unusable for its purpose.
> I have upgraded Xen from 3.2.1 to 3.3, and the problem remains, which 
> means I have changed:
> 1) Change domU kernel (2.6.21, 2.6.24, 2.6.25)
> 2) Change domU userland (gentoo, ubuntu)
> 3) Change dom0 physical nic + driver (Realtek 8169 -> 8168)
> 4) Change Xen version (3.2.1 -> 3.3)
>
> The only thing I haven't changed is the dom0 kernel. I am using a stock 
> 2.6.21-xen gentoo kernel, so it would be great if anyone watching this 
> that has pv domUs working under a 2.6.21 kernel would post their .config 
> so I can compare it to mine.
> Thanks,
>
> Paul
>
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