Re: [Xen-devel] Xen3 domU network packet loss (udp iperf)

[Pasi Kärkkäinen <pasik@xxxxxx>]

On Wed, Mar 22, 2006 at 06:44:52PM -0500, Andrew D. Ball wrote:
> I wonder if this is why I've never seen a domU kernel finish booting 
> with ip="dhcp" in the Python configuration file.
> 
> This translates to an "ip=:::::eth0:dhcp" kernel parameter, so the domU 
> seems to be using the DHCP client embedded in the Linux kernel.
> 
> It always times out for me, but I haven't found time to dig deeper into 
> what's going wrong.
> 
> Has anyone else had better luck?
>

I also noticed that when doing both the incoming and outgoing transfers
simultaneously, the incoming speed to domU is 1/2 of the speed of outgoing 
speed (or even lower).

with iperf "Do a bidirectional test simultaneously" test:

outside -> domU: 175 Mbits/sec
domU -> outside: 392 Mbits/sec

What could explain that?

- Pasi
 
> Thanks for your help.
> Andrew
> =============
> Andrew D. Ball <aball@xxxxxxxxxx>
> 
> Pasi Kärkkäinen wrote:
> >And you won't notice this packet loss with TCP, because TCP automatically
> >re-transmits the missing packets.. TCP speed does suffer, however.
> >
> >Others seeing this?
> >
> >- Pasi
> >
> >On Sat, Mar 18, 2006 at 03:04:13PM +0200, Pasi Kärkkäinen wrote:
> >
> >>Hi!
> >>
> >>Please check out this URL: http://nrg.joroinen.fi/xen-ploss.txt
> >>
> >>There you have UDP iperf results to and from domU and dom0.
> >>
> >>It seems xen causes packet loss to domU's.. dom0 works well without packet
> >>loss.
> >>
> >>Is this known problem? I'm using bridged networking with xen.
> >>
> >>Both the xen box, and the external non-xen box were P4 3.0+ GHz, using
> >>gigabit NIC's (tg3 and e1000).
> >>
> >>in the xen box, all the physical network interfaces (tg3) have rx and tx 
> >>checksumming on.
> >>
> >>I'm using xen 3 unstable from 2006-02-04.
> >>
> >>-- Pasi
> >>
> >
> >
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> >http://lists.xensource.com/xen-devel
> 
> 

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