On Mon, Jul 17, 2017 at 07:27:24 -0400, sferdjao@redhat.com wrote:
From: Sahid Orentino Ferdjaoui <sahid.ferdjaoui@redhat.com>
In version 2.7.0, QEMU introduced support of busy polling for vhost-net [0]. To avoid paraphrasing original authors of that feature and the purpose it I prefer to share a pointer [1].
This patch serie exposes throught the NIC driver-specific element a new option 'poll_us'. That option is only available with the backend driver 'vhost' and that because libvirt automatically fallback to QEMU if the driver is not specified where that option is not available.
The option 'poll_us' takes a positive. 0 means that the option is not going to be exposed.
We had a similar attempt to do this for disk polling, but that was rejected since it's not very straightforward for the users to tune this variable. I think this falls into the same category. Here's the discussion for iothread polling: https://www.redhat.com/archives/libvir-list/2017-February/msg01048.html