[libvirt] is it possible to set txqueuelen on vnetX devices automatically

[Daniel P. Berrange]

On Mon, Apr 02, 2012 at 05:15:55PM +0100, Tim Hughes wrote:
> Hello,
> 
> We have been tuning our libvirt hosts and discovered that setting the
> txqueuelen on vnetX devices to 2500 we can increase the network throughput
> by a factor of almost 10. On an eth device it can be set by  hand/rc.local
> with the following instructions
> http://www.cyberciti.biz/faq/gentoo-centos-rhel-debian-fedora-increasing-txqueuelen/
> .  Because vnetX devices are named on a 'first free' basis and they come
> and go with the guests the rc.local method is not going to work. I think
> this needs to be done via libvirt or possibly udev, maybe with some kind of
> hook. Ideally I would like to be able to set this automatically for all
> vnetX devices when they are created or even better, on a per guest basis.

You can probably do this with a hook script:

  http://libvirt.org/hooks.html

Please also file a BZ requesting that this tunable be directly supported
by libvirt.

Daniel
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