Re: [Qemu-devel] [RFC PATCH] virtio-mmio: support for multiple irqs

[Shannon Zhao]

On 2014/11/4 17:35, Shannon Zhao wrote:
> As the current virtio-mmio only support single irq,
> so some advanced features such as vhost-net with irqfd
> are not supported. And the net performance is not
> the best without vhost-net and irqfd supporting.
> 
Hi Joel, Peter, Mst,

Some virtio-net with virtio-mmio performance data on ARM added as followed:

Type of backend         bandwith(GBytes/sec)
virtio-net              0.66
vhost-net               1.49
vhost-net with irqfd    2.01

Test cmd: ./iperf -c 192.168.0.2 -P 1 -i 10 -p 5001 -f G -t 60

>From this test data, irqfd has great improvement (about 30%) on performance.
So maybe it's necessary to enable multiple irq support to make vhost-net
with virtio-mmio on ARM be able to use irqfd.

How do you guys think? Look forward for your feedback.

Thanks,
Shannon

> This patch support virtio-mmio to request multiple
> irqs like virtio-pci. With this patch and qemu assigning
> multiple irqs for virtio-mmio device, it's ok to use
> vhost-net with irqfd on arm/arm64.
>