[libvirt-users] How can a bridge be optimized?

[Whit Blauvelt]

On Tue, Jun 12, 2012 at 03:37:00PM +0300, Henrik Ahlgren wrote:
> On Mon, Jun 11, 2012 at 03:28:59PM -0400, Whit Blauvelt wrote:
> > I get around 150Mb, (on a Gb interface). But then its still showing as
> > "-device rtl8139" on the host. Should that be?
> 
> That clearly indicates you are not running with a virtio NIC. You
> should see "-device virtio-net-pci" in the process list.
> 
> What versions of livirt and kvm/qemu are you running? What is the
> guest's operating system? Does it also report rtl8139 (lshw, ethtool -i eth0)?

The host is Ubuntu 10.10 with the 2.6.35-28-server kernel. Libvirt is
0.8.3-1ubuntu19.4, qemu-kvm is 0.12.5+noroms-0ubuntu7.11. Not sure how that
relates to "Get kvm version >= 60" (from http://www.linux-kvm.org/page/Virtio)
but it's at least a "Kernel >= 2.6.25". 

The process list shows "-device virtio-balloon-pci", so virtio is at least
partially there. But also, "-device rtl8139", so this part of the XML
appears not to be taking:

    <interface type='bridge'>
      <mac address='00:16:36:89:65:2e'/>
      <source bridge='br0'/>            
      <address type='pci' domain='0x0000' bus='0x00' slot='0x03' function='0x0'/>
      <model type='virtio'/>                                                     
    </interface>            

Even though, oddly, it's consistently 50% faster with the virtio line than
without. 

The guest is running Ubuntu 11.10 with the 3.0.0-20-virtual kernel. The
guest reports:

# ethtool -i eth0
driver: 8139cp

The physical NIC is an Intel 82576 using the igb driver.

Thanks,
Whit