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