Re: [Qemu-devel] [PATCH 1/8] virtio: don't waste irqfds on control vqs

[Stefan Hajnoczi]

On Wed, Dec 26, 2012 at 12:52:19PM +0200, Michael S. Tsirkin wrote:
> Pass nvqs to set_guest_notifiers. This makes it possible to
> save on irqfds by not allocating one for the control vq
> for virtio-net.
> 
> Signed-off-by: Michael S. Tsirkin <address@hidden>
> ---
>  hw/vhost.c      | 10 +++++++---
>  hw/virtio-pci.c | 19 ++++++++++++++-----
>  hw/virtio-pci.h |  1 +
>  hw/virtio.h     |  2 +-
>  4 files changed, 23 insertions(+), 9 deletions(-)

Good idea!

This patch assumes only the first n virtqueues need irqfd.  Depending on
the device's virtqueue ordering this may not work (e.g. control vq first
followed by data vqs).  But this is a theoretical point, let's wait
until we hit it and need something fancier.

Stefan