Re: [Qemu-devel] The status about vhost-net on kvm-arm?

[Joel Schopp <joel.schopp@amd.com>]

>>>> we at Virtual Open Systems did some work and tested vhost-net on ARM
>>>> back in March.
>>>> The setup was based on:
>>>>   - host kernel with our ioeventfd patches:
>>>> http://www.spinics.net/lists/kvm-arm/msg08413.html
>>>>
>>>> - qemu with the aforementioned patches from Ying-Shiuan Pan
>>>> https://lists.gnu.org/archive/html/qemu-devel/2014-02/msg00715.html
>>>>
>>>> The testbed was ARM Chromebook with Exynos 5250, using a 1Gbps USB3
>>>> Ethernet adapter connected to a 1Gbps switch. I can't find the actual
>>>> numbers but I remember that with multiple streams the gain was clearly
>>>> seen. Note that it used the minimum required ioventfd implementation
>>>> and not irqfd.
>>>>
>>>> I guess it is feasible to think that it all can be put together and
>>>> rebased + the recent irqfd work. One can achiev even better
>>>> performance (because of the irqfd).
>>>>
>>> Managed to replicate the setup with the old versions e used in March:
>>>
>>> Single stream from another machine to chromebook with 1Gbps USB3
>>> Ethernet adapter.
>>> iperf -c <address> -P 1 -i 1 -p 5001 -f k -t 10
>>> to HOST: 858316 Kbits/sec
>>> to GUEST: 761563 Kbits/sec
>> to GUEST vhost=off: 508150 Kbits/sec
>>> 10 parallel streams
>>> iperf -c <address> -P 10 -i 1 -p 5001 -f k -t 10
>>> to HOST: 842420 Kbits/sec
>>> to GUEST: 625144 Kbits/sec
>> to GUEST vhost=off: 425276 Kbits/sec
> I have tested the same cases on a Hisilicon board (Cortex-A15@1G)
> with Integrated 1Gbps Ethernet adapter.
>
> iperf -c <address> -P 1 -i 1 -p 5001 -f M -t 10
> to HOST: 906 Mbits/sec
> to GUEST: 562 Mbits/sec
> to GUEST vhost=off: 340 Mbits/sec
>
> 10 parallel streams, the performance gets <10% plus:
> iperf -c <address> -P 10 -i 1 -p 5001 -f M -t 10
> to HOST: 923 Mbits/sec
> to GUEST: 592 Mbits/sec
> to GUEST vhost=off: 364 Mbits/sec
>
> I't easy to see vhost-net brings great performance improvements,
> almost 50%+.
That's pretty impressive for not even having irqfd.  I guess we should 
renew some effort to get these patches merged upstream.