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

[Shannon Zhao <zhaoshenglong@huawei.com>]

On 2014/11/5 23:27, Joel Schopp wrote:
> 
> On 11/05/2014 03:12 AM, Shannon Zhao wrote:
>> Hi Rémy,
>>
>> On 2014/11/5 16:26, GAUGUEY Rémy 228890 wrote:
>>> Hi Shannon, 
>>>
>>>> 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
>>> Impressive results !
>>> Could you please detail your setup ? which platform are you using and which GbE controller ?
>> Sorry for not telling the test scenario. This test scenario is from Host to Guest. It just
>> compare the performance of different backends. I did this test on ARM64 platform.
>>
>> The setup was based on:
>> 1)on host kvm-arm should support ioeventfd and irqfd
>> 	The irqfd patch is from Eric "ARM: KVM: add irqfd support".
>> 	http://www.spinics.net/lists/kvm-arm/msg11014.html
>>
>> 	The ioeventfd patch is reworked by me from Antonios.
>> 	http://www.spinics.net/lists/kvm-arm/msg08413.html
>>
>> 2)qemu should enable ioeventfd support for virtio-mmio
>> 	This patch is refer to Ying-Shiuan Pan and reworked for new qemu branch.
>> 	https://lists.gnu.org/archive/html/qemu-devel/2014-11/msg00594.html
>>
>> 3)qemu should enable multiple irqs for virtio-mmio
>> 	This patch isn't sent to qemu maillist as we want to check whether this is the right direction.
>> 	If you want to test, I'll send it to you.
> I'm not a maintainer so my opinion isn't worth a lot here, but this
> seems like the right direction to me.  I'd like to see the qemu patch
> (do mention the dependency on the kernel patch) on the qemu-devel
> mailing list.  I think these numbers also support some of the prereqs
> listed above that have gone through several iterations getting queued up
> for 3.19.
> .
> 
Hi,

Thanks for your reply :)
If this patch get accepted by maintainers, I'll send the qemu patch to qemu-devel mailing list.

In addition, I think this is worth on arm32 platform as arm32 with GICv2 doesn't support MSI.
So it can't use virtio-pci if I don't miss something. And it's also worth on arm64 platform
as we can't make sure when the PCI and MSI are supported on arm. It give users an alternative
choice for virtualization network.

Rusty, MST, Peter Maydell, do you have any ideas about this? Waiting for your feedback :)

Thanks
-- 
Shannon