Re: [Xen-users] 10Gbit ethernet NIC gives slow throughput

[fabi.a169@xxxxxxxxx]

Pasi Kärkkäinen wrote:
> On Mon, Dec 22, 2008 at 05:36:40PM +0100, fabi.a169@xxxxxxxxx wrote:
>   
> > Hello,
> >
> > I would like to use a server having myricom 10gbit ethernet interfaces
> > (driver myri10ge) for Xen. But between dom0s (no domU running), I get only a
> > throughput of about 2.3Gbit/s (I use Xen 3.2 with the 2.6.18 kernel and
> > debian in dom0), whether xend is running or not.  However, on linux kernel
> > with the same version but without xen patch, I get more than 6Gbit/s.
> > Clearly, with Xen, the CPU is not the bottleneck, beeing used at much less
> > than 100%.
> >
> > Does anybody have experiences with Xen and 10Gbit ethernet ?
> >
> >     
> With Xen, are you using bridged networking? 
>
> The default network configuration in Xen creates virtual ethernet interface 
> called
> 'eth0', which is bridged to the real NIC (which is renamed to peth0).
>
> So, when making comparisons, make sure you're using the actual physical interface. 
>
> Dunno if there's something to optimize in the bridge-setup.. have you done
> all the normal optimizations? txqueuelen for all interfaces (including vif
> interfaces), tcp window sizes etc.
>
> -- Pasi
>
>   
I don't even use the brigdes, for example without starting xend. Also, 
when I measure throughput on the loopback interface, I get the same 
throughput bounded to 2.29 Gbps. There should be something bounding 
everything to this value, maybe related to the vcpus. If I send for 
example 2 flows in parallel, I get the double of this throughput.
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