Description of problem:
Request for adding deployment option to director to set rx_queue_size and  tx_queue_size in /etc/libvirt/qemu.conf

The current libvirt patch, proposed by Michal Privoznik https://www.redhat.com/archives/libvir-list/2018-January/msg00608.html , enables setting rx_queue_size and tx_queue_size in /etc/libvirt/qemu.conf,  which would enable libvirt to set <driver rx/tx_queue_size=''/> in VM/Instance xml, if rx/tx_queue_size is not explicitly defined in VM/Instance xml.

In case rx_queue_size or tx_queue_size is not explicitly set in  /etc/libvirt/qemu.conf  or qemu-kvm not supporting queue size (for example tx_queue_size in case of older qemu) and <driver rx/tx_queue_size=''/> not set in VM xml, which would be the case for openstack, rx/tx_queue_size would be set to the default value of 256 set by qemu.This bug would resolve setting rx_queue_size and tx_queue_size on per-host basis.

Once libvirt patch is part of a release, will open a separate bug for OSP10, to track back-porting of this feature and libvirt to OSP10.

upstream Libvirt patch:
https://www.redhat.com/archives/libvir-list/2018-January/msg00608.html