Re: [dpdk-dev] [PATCH v1 0/3] Introduce new class for vDPA device drivers

[Matan Azrad <matan@mellanox.com>]

From: Xu, Rosen <rosen.xu@intel.com>
> > -----Original Message-----
> > From: Thomas Monjalon <thomas@monjalon.net>
> > Sent: Thursday, January 09, 2020 16:41
> > To: Xu, Rosen <rosen.xu@intel.com>
> > Cc: Matan Azrad <matan@mellanox.com>; Maxime Coquelin
> > <maxime.coquelin@redhat.com>; Bie, Tiwei <tiwei.bie@intel.com>; Wang,
> > Zhihong <zhihong.wang@intel.com>; Wang, Xiao W
> > <xiao.w.wang@intel.com>; Yigit, Ferruh <ferruh.yigit@intel.com>;
> > dev@dpdk.org; Pei, Andy <andy.pei@intel.com>
> > Subject: Re: [dpdk-dev] [PATCH v1 0/3] Introduce new class for vDPA
> > device drivers
> >
> > 09/01/2020 03:27, Xu, Rosen:
> > > Hi,
> > >
> > > From: Thomas Monjalon <thomas@monjalon.net>
> > > > 08/01/2020 13:39, Xu, Rosen:
> > > > > From: Matan Azrad <matan@mellanox.com>
> > > > > > From: Xu, Rosen
> > > > > > > Did you think about OVS DPDK?
> > > > > > > vDPA is a basic module for OVS, currently it will take some
> > > > > > > exception path packet processing for OVS, so it still needs
> > > > > > > to integrate
> > > > eth_dev.
> > > > > >
> > > > > > I don't understand your question.
> > > > > >
> > > > > > What do you mean by "integrate eth_dev"?
> > > > >
> > > > > My questions is in OVS DPDK scenario vDPA device implements
> > > > > eth_dev ops, so create a new class and move ifc code to this new
> > > > > class
> > is not ok.
> > > >
> > > > 1/ I don't understand the relation with OVS.
> > > >
> > > > 2/ no, vDPA device implements vDPA ops.
> > > > If it implements ethdev ops, it is an ethdev device.
> > > >
> > > > Please show an example of what you claim.
> > >
> > > Answers of 1 and 2.
> > >
> > > In OVS DPDK, each network device(such as NIC, vHost etc) of DPDK
> > > needs to be implemented as rte_eth_dev and provides eth_dev_ops
> such
> > > as
> > packet TX/RX for OVS.
> >
> > No, OVS is also using the vhost API for vhost port.
> 
> Yes, vhost pmd is not a good example.
> 
> > > Take vHost(Virtio back end) for example, OVS startups vHost
> > > interface like
> > this:
> > > ovs-vsctl add-port br0 vhost-user-1 -- set Interface vhost-user-1
> > > type=dpdkvhostuser drivers/net/vhost implements vHost as
> rte_eth_dev
> > and integrated in OVS.
> > > OVS can send/receive packets to/from VM with rte_eth_tx_burst()
> > > rte_eth_rx_burst() which call eth_dev_ops implementation of
> > drivers/net/vhost.
> >
> > No, it is using rte_vhost_dequeue_burst() and
> > rte_vhost_enqueue_burst() which are not in ethdev.
> >
> > > vDPA is also Virtio back end and works like vHost, same as vHost, it
> > > will be implemented as rte_eth_dev and also be integrated into OVS.
> >
> > No, vDPA is not "implemented as rte_eth_dev".
> 
> Currently, vDPA isn't integrated with OVS.
> 
> > > So, it's not ok to move ifc code from drivers/net.
> >
> > drivers/net/ifc has no ethdev implementation at all.
> 
> For OVS hasn't integrated vDPA, it doesn't implement rte_eth_dev, but
> there are many discussions in OVS community about vDPA, some are from
> Mellanox, it seems vDPA port will be implemented as rte_eth_dev port in
> OVS in the near feature.
> https://eur03.safelinks.protection.outlook.com/?url=https%3A%2F%2Fpatch
> work.ozlabs.org%2Fpatch%2F1178474%2F&amp;data=02%7C01%7Cmatan%4
> 0mellanox.com%7C9e84c2581e2f414e0aca08d794f22e8d%7Ca652971c7d2e4d
> 9ba6a4d149256f461b%7C0%7C0%7C637141640216181763&amp;sdata=TA%2F
> 0zU495kXUqhC6eP09NDzBZfjJz1dbfkRcDpV%2BYAs%3D&amp;reserved=0
> 
> Matan,
> Could you clarify how OVS integrates vDPA in Mellanox patch?
> 
> >
> > Rosen, I'm sorry, these arguments look irrelevant, so I won't consider
> > them as blocking the integration of this patch.
> 
> What I mentioned is not blocking the integration of this patch, I just want to
> get clarification from Matan how to integrate vDPA port in OVS.


Hi

OVS like any other application should use the current API of vDPA to attach a probed vdpa device to a vhost device.
See example application /examples/vdpa.

Here, we just introduce a new class to hold all the vDPA drivers, no change in the API.

As I understand, no vDPA device is currently integrated in OVS.

I think it can be integrated only when a full offload will be integrated since the vDPA device forward the traffic from the HW directly to the virtio queue, once it will be there, I guess the offload will be configured by the representor of the vdpa device(VF) which is managed by an ethdev device.


Matan.