Re: [PATCH V2] virtio-net: calculating proper msix vectors on init

[Philippe Mathieu-Daudé]

On 3/9/21 5:23 AM, Jason Wang wrote:
> Currently, the default msix vectors for virtio-net-pci is 3 which is
> obvious not suitable for multiqueue guest, so we depends on the user
> or management tools to pass a correct vectors parameter. In fact, we
> can simplifying this by calculating the number of vectors on realize.
> 
> Consider we have N queues, the number of vectors needed is 2*N + 2
> (#queue pairs + plus one config interrupt and control vq). We didn't
> check whether or not host support control vq because it was added
> unconditionally by qemu to avoid breaking legacy guests such as Minix.
> 
> Signed-off-by: Jason Wang <jasowang@redhat.com>
> ---
> Changes since v1:
> - Fix typo in the commit log
> - Explain the magic number during vectors calculation
> ---
>  hw/core/machine.c          |  1 +
>  hw/virtio/virtio-net-pci.c | 10 +++++++++-
>  2 files changed, 10 insertions(+), 1 deletion(-)

(the patch had Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>)

Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>