Re: [dpdk-dev] [RFC 0/7] PMD driver for AF_XDP

["Zhang, Qi Z" <qi.z.zhang@intel.com>]

> -----Original Message-----
> From: Jason Wang [mailto:jasowang@redhat.com]
> Sent: Thursday, March 1, 2018 9:18 PM
> To: Zhang, Qi Z <qi.z.zhang@intel.com>
> Cc: Karlsson, Magnus <magnus.karlsson@intel.com>; Topel, Bjorn
> <bjorn.topel@intel.com>; dev@dpdk.org
> Subject: Re: [dpdk-dev] [RFC 0/7] PMD driver for AF_XDP
> 
> 
> 
> On 2018年03月01日 20:56, Zhang, Qi Z wrote:
> >>>>>> BTW, performance test shows our PMD can reach 94%~98% of the
> >>>>>> orignal benchmark when share memory is enabled.
> >>>>> Hi:
> >>>>>
> >>>>> Looks like zero copy is not used in this series. Any plan to support
> that?
> >>>> Zero copy is enabled in patch 5, if a mempool passed check_mempool,
> >>>> it will be registered to af_xdp socket.
> >>>> so there will be no memcpy between mbuf and af_xdp.
> >> Aha, I see. So the zerocopy was limited to some specific use case.
> >> And if I understand it correctly, zc mode could not be used for VM.
> > I think except the limitation for mempool layout, zerocopy is transparent
> to DPDK application, only difference is performance.
> > Sorry, I may not get your point, if you could explain more about the VM
> usage.
> >
> > Regards
> > Qi
> 
> No problem, so the question is:
> 
> Can zerocopy be used when using testpmd to foward packets between
> vhost-user and AF_XDP socket?

I'm not very familiar with vhost-user, but I guess the answer should be same as the case for forward packet between vhost-user and i40e, 
(if vhost-user does not have any special requirement for mempool that conflict with af_xdp ZC's requirement)

Regards
Qi

> 
> Thanks