Slow network performance since Virtio net drivers are always disabled

[Vish Ishaya]

Right now virtio drivers are commented out which leads to abysmally slow networking. We need a flag of somesort in the kernel json (and probably image as well for whole image booting) saying whether it supports virtio.

[Vladimir Vuksan (vlists)]

By default Qemu will use 8139 drivers which is 100 Mbit. If people are uncomfortable with virtio we should set the model to e1000 as that is a Gigabit interface.

[Tom Fifield (fifieldt)]

So, now there is a flag:

libvirt_use_virtio_for_bridges

to enable virtio on a cloud-wide basis. Is that a solution for this bug?

Though I think Vladmir has a good point - if there is no virtio, perhaps another NIC model could be more appropriate than default. You could potentially extend the virtio flag to be model choice, or try to provide best performance based on models available ...

qemu -net nic,model=? /dev/null
qemu: Supported NIC models: ne2k_pci,i82551,i82557b,i82559er,rtl8139,e1000,pcnet,virtio

[Russell Bryant (russellb)]

virtio is now used by default, but you can also configure it using hardware config properties on images in glance.

See:

https://blueprints.launchpad.net/nova/+spec/libvirt-custom-hardware