Re: [RFC] lib/librte_vhost: qemu vhost-user support into DPDK vhost library

["Tetsuya.Mukawa" <mukawa-AlSX/UN32fvPDbFq/vQRIQ@public.gmane.org>]

(2014/08/27 14:27), Tetsuya.Mukawa wrote:
> Hi Changchun,
>
> (2014/08/27 14:01), Ouyang, Changchun wrote:
>> Agree with you, the performance should be same as the data path (RX/TX) is not affected,
>> The difference between implementation only exists in the virtio device creation and destroy stage.
> Yes, I agree. Also There may be the difference, if a virtio-net driver
> on a guest isn't poll mode like a virtio-net device driver in the
> kernel. In the case, existing vhost implementation uses the eventfd
> kernel module, and vhost-user implementation uses eventfd to kick the
> driver. So I guess there will be the difference.
>
> Anyway, about device creation and destruction, the difference will come
> from transmission speed between unix domain socket and CUSE. I am not
> sure which is faster.
Thank for pointing out my misleading expression.

Correct: transmission latency
Incorrect: transmission speed

Tetsuya,


>
> Thanks,
> Tetsuya
>
>
>> Regards,
>> Changchun
>>
>>> -----Original Message-----
>>> From: Tetsuya.Mukawa [mailto:mukawa-AlSX/UN32fvPDbFq/vQRIQ@public.gmane.org]
>>> Sent: Wednesday, August 27, 2014 12:39 PM
>>> To: Ouyang, Changchun; dev-VfR2kkLFssw@public.gmane.org
>>> Cc: Xie, Huawei; Katsuya MATSUBARA; nakajima.yoshihiro-Zyj7fXuS5i5L9jVzuh4AOg@public.gmane.org;
>>> Hitoshi Masutani
>>> Subject: Re: [dpdk-dev] [RFC] lib/librte_vhost: qemu vhost-user support into
>>> DPDK vhost library
>>>
>>>
>>> (2014/08/27 9:43), Ouyang, Changchun wrote:
>>>> Do we have performance comparison between both implementation?
>>> Hi Changchun,
>>>
>>> If DPDK applications are running on both guest and host side, the
>>> performance should be almost same, because while transmitting data virt
>>> queues are accessed by virtio-net PMD and libvhost. In libvhost, the existing
>>> vhost implementation and a vhost-user implementation will shares or uses
>>> same code to access virt queues. So I guess the performance will be almost
>>> same.
>>>
>>> Thanks,
>>> Tetsuya
>>>
>>>
>>>> Thanks
>>>> Changchun
>>>>
>>>>
>>>> -----Original Message-----
>>>> From: dev [mailto:dev-bounces-VfR2kkLFssw@public.gmane.org] On Behalf Of Xie, Huawei
>>>> Sent: Tuesday, August 26, 2014 7:06 PM
>>>> To: dev-VfR2kkLFssw@public.gmane.org
>>>> Subject: Re: [dpdk-dev] [RFC] lib/librte_vhost: qemu vhost-user
>>>> support into DPDK vhost library
>>>>
>>>> Hi all:
>>>> We are implementing qemu official vhost-user interface into DPDK vhost
>>> library, so there would be two coexisting implementations for user space
>>> vhost backend.
>>>> Pro and cons in my mind:
>>>> Existing solution:
>>>> Pros:  works with qemu version before 2.1;  Cons: depends on eventfd
>>> proxy kernel module and extra maintenance effort Qemu vhost-user:
>>>>                Pros:  qemu official us-vhost interface;     Cons: only available after
>>> qemu 2.1
>>>> BR.
>>>> huawei