Re: [Qemu-devel] [virtio-dev] Re: [virtio-dev] Re: [PATCH v2 00/16] Vhost-pci for inter-VM communication

[Wei Wang <wei.w.wang@intel.com>]

On 05/23/2017 10:08 AM, Jason Wang wrote:
>
>
> On 2017年05月22日 19:46, Wang, Wei W wrote:
>> On Monday, May 22, 2017 10:28 AM, Jason Wang wrote:
>>> On 2017年05月19日 23:33, Stefan Hajnoczi wrote:
>>>> On Fri, May 19, 2017 at 11:10:33AM +0800, Jason Wang wrote:
>>>>> On 2017年05月18日 11:03, Wei Wang wrote:
>>>>>> On 05/17/2017 02:22 PM, Jason Wang wrote:
>>>>>>> On 2017年05月17日 14:16, Jason Wang wrote:
>>>>>>>> On 2017年05月16日 15:12, Wei Wang wrote:
>>>>>>>>>> Hi:
>>>>>>>>>>
>>>>>>>>>> Care to post the driver codes too?
>>>>>>>>>>
>>>>>>>>> OK. It may take some time to clean up the driver code before post
>>>>>>>>> it out. You can first have a check of the draft at the repo here:
>>>>>>>>> https://github.com/wei-w-wang/vhost-pci-driver
>>>>>>>>>
>>>>>>>>> Best,
>>>>>>>>> Wei
>>>>>>>> Interesting, looks like there's one copy on tx side. We used to
>>>>>>>> have zerocopy support for tun for VM2VM traffic. Could you please
>>>>>>>> try to compare it with your vhost-pci-net by:
>>>>>>>>
>>>>>> We can analyze from the whole data path - from VM1's network stack
>>>>>> to send packets -> VM2's network stack to receive packets. The
>>>>>> number of copies are actually the same for both.
>>>>> That's why I'm asking you to compare the performance. The only reason
>>>>> for vhost-pci is performance. You should prove it.
>>>> There is another reason for vhost-pci besides maximum performance:
>>>>
>>>> vhost-pci makes it possible for end-users to run networking or storage
>>>> appliances in compute clouds.  Cloud providers do not allow end-users
>>>> to run custom vhost-user processes on the host so you need vhost-pci.
>>>>
>>>> Stefan
>>> Then it has non NFV use cases and the question goes back to the 
>>> performance
>>> comparing between vhost-pci and zerocopy vhost_net. If it does not 
>>> perform
>>> better, it was less interesting at least in this case.
>>>
>> Probably I can share what we got about vhost-pci and vhost-user:
>> https://github.com/wei-w-wang/vhost-pci-discussion/blob/master/vhost_pci_vs_vhost_user.pdf 
>>
>> Right now, I don’t have the environment to add the vhost_net test.
>
> Thanks, the number looks good. But I have some questions:
>
> - Is the number measured through your vhost-pci kernel driver code?

Yes, the kernel driver code.

> - Have you tested packet size other than 64B?

Not yet.

> - Is zerocopy supported in OVS-dpdk? If yes, is it enabled in your test?
zerocopy is not used in the test, but I don't think zerocopy can increase
the throughput to 2x. On the other side, we haven't put effort to optimize
the draft kernel driver yet.

Best,
Wei