Re: [Qemu-devel] [PING-2 PATCH v3 0/3] virtio-mmio: introduce eventfd support

Re: [Qemu-devel] [PING-2 PATCH v3 0/3] virtio-mmio: introduce eventfd support

[Pavel Fedin]

 Hello everybody! This is my second PING on this. I have seen no response to v3. Changes
since to v2 are:
1. Properly formatted (i really hope so...)
2. Added reset handling.
 I decided to leave this as three patches because host and guest notifiers should be both
implemented in order to make use of them. So, enabling host notifiers does not make sense
without guest ones.

Kind regards,
Pavel Fedin
Expert Engineer
Samsung Electronics Research center Russia


> -----Original Message-----
> From: qemu-devel-bounces+p.fedin=samsung.com@nongnu.org [mailto:qemu-devel-
> bounces+p.fedin=samsung.com@nongnu.org] On Behalf Of Pavel Fedin
> Sent: Tuesday, May 12, 2015 11:11 AM
> To: qemu-devel@nongnu.org
> Cc: Pavel Fedin; Ying-Shiuan Pan
> Subject: [Qemu-devel] [PATCH v3 0/3] virtio-mmio: introduce eventfd support
> 
>  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.
> 
> 
> 
> Ying-Shiuan Pan (3):
>   virtio-mmio: introduce set_host_notifier()
>   virtio-mmio: introduce set_guest_notifiers
>   virtio-mmio: start ioeventfd when status gets DRIVER_OK
> 
>  hw/virtio/virtio-mmio.c | 181 ++++++++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 181 insertions(+)
> 
> --
> 1.9.5.msysgit.0