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 02:32 PM, Jason Wang wrote:
>
>
> On 2017年05月23日 13:47, Wei Wang wrote:
>> 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.
>
> Interesting, in the above link, "l2fwd" was used in vhost-pci testing. 
> I want to know more about the test configuration: If l2fwd is the one 
> that dpdk had, want to know how can you make it work for kernel 
> driver. (Maybe packet socket I think?) If not, want to know how do you 
> configure it (e.g through bridge or act_mirred or others). And in OVS 
> dpdk, is dpdk l2fwd + pmd used in the testing?
>

Oh, that l2fwd is a kernel module from OPNFV vsperf
(http://artifacts.opnfv.org/vswitchperf/docs/userguide/quickstart.html)
For both legacy and vhost-pci cases, they use the same l2fwd module.
No bridge is used, the module already works at L2 to forward packets
between two net devices.

Best,
Wei