Re: [Qemu-devel] [PATCH v3 0/3] virtio-mmio: introduce eventfd support

[Peter Maydell]

On 12 May 2015 at 09:10, Pavel Fedin <address@hidden> wrote:
>  This patch set introduces eventfd support for virio-mmio. It was originally
> published by Ying-Shiuan Pan but never got it to upstream:
> https://lists.gnu.org/archive/html/qemu-devel/2014-02/msg00715.html
>  I have updated and successfully tested it with vhost-net. I confirm that this
> solution significantly improves the network performance even without irqfd.
>  I would like to upstream it, since virtio-mmio is still there. I know that
> some of you consider it deprecated, however i believe this is not entirely
> true. Because you can add it to machine models which are not supposed to
> have PCI (like vexpress).
>  An old patch set relied on additional "eventfd" option in order to disable
> the support if not implemented in kernel. My version simply checks
> kvm_eventfds_enabled() for this purpose, so backwards compatibility is much
> better.
>  I decided to leave this set in three parts because ioeventfd support should
> be enabled only when both host and guest notifiers are in place. I believe
> it will not work with partial implementation, at least because vhost-net
> requires both sets of eventfds. In this version i added correct reset 
> handling.

Hi Pavel. I've been going through my to-review folder and found this
series from back in May lurking in it. Sorry I never got to reviewing it.
Do you think it's still a change worth having? If so, please can you
rebase and resend and I'll look at it this time around.

thanks
-- PMM