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

[Shannon Zhao]

Hi Nikolay,
>From this mail I know you guys have done some work about ioeventfd support
on kvm-arm before. Do you have plan to rework your patch based on
the new branch? If not, I think we should send a patch to make eventfd
support on kvm-arm and make vhost-net work.

Based on the new kvm-arm branch with Eric's patch "ARM: KVM: add irqfd support"
and eventfd patch in both kvm and qemu we have run virtio-mmio with vhost-net.
And with our patch to enable virtio-mmio multiple irq and irqfd support, it
work well to run vhost-net with irqfd on ARM.

The performance test data as followed :

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

>From this test data, vhost-net and irqfd have great improvement on performance.
So maybe it's necessary to enable ioeventfd make vhost-net work with
virtio-mmio on ARM.

It's ok if I send these patches?
Thanks,
Shannon

On 2014/8/12 23:47, Nikolay Nikolaev wrote:
> Hello,
> 
> 
> On Tue, Aug 12, 2014 at 5:41 AM, Li Liu <address@hidden> wrote:
>>
>> Hi all,
>>
>> Is anyone there can tell the current status of vhost-net on kvm-arm?
>>
>> Half a year has passed from Isa Ansharullah asked this question:
>> http://www.spinics.net/lists/kvm-arm/msg08152.html
>>
>> I have found two patches which have provided the kvm-arm support of
>> eventfd and irqfd:
>>
>> 1) [RFC PATCH 0/4] ARM: KVM: Enable the ioeventfd capability of KVM on ARM
>> http://lists.gnu.org/archive/html/qemu-devel/2014-01/msg01770.html
>>
>> 2) [RFC,v3] ARM: KVM: add irqfd and irq routing support
>> https://patches.linaro.org/32261/
>>
>> And there's a rough patch for qemu to support eventfd from Ying-Shiuan Pan:
>>
>> [Qemu-devel] [PATCH 0/4] ioeventfd support for virtio-mmio
>> https://lists.gnu.org/archive/html/qemu-devel/2014-02/msg00715.html
>>
>> But there no any comments of this patch. And I can found nothing about qemu
>> to support irqfd. Do I lost the track?
>>
>> If nobody try to fix it. We have a plan to complete it about virtio-mmio
>> supporing irqfd and multiqueue.
>>
>>
> 
> 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).
> 
>>
>>
>>
>>
>>
>> _______________________________________________
>> kvmarm mailing list
>> address@hidden
>> https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
> 
> 
> regards,
> Nikolay Nikolaev
> Virtual Open Systems
> _______________________________________________
> kvmarm mailing list
> address@hidden
> https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
> 
> 

-- 
Shannon