[PATCH v5 3/8] net/gve: add support for device initialization

[Xia, Chenbo]

> -----Original Message-----
> From: Ferruh Yigit <ferruh.yigit at amd.com>
> Sent: Wednesday, October 19, 2022 9:47 PM
> To: Guo, Junfeng <junfeng.guo at intel.com>; Zhang, Qi Z
> <qi.z.zhang at intel.com>; Wu, Jingjing <jingjing.wu at intel.com>; Maxime
> Coquelin <maxime.coquelin at redhat.com>; Xia, Chenbo <chenbo.xia at intel.com>
> Cc: dev at dpdk.org; Li, Xiaoyun <xiaoyun.li at intel.com>;
> awogbemila at google.com; Richardson, Bruce <bruce.richardson at intel.com>; Lin,
> Xueqin <xueqin.lin at intel.com>; Wang, Haiyue <haiyue.wang at intel.com>; Zhang,
> Helin <helin.zhang at intel.com>; Thomas Monjalon <thomas at monjalon.net>
> Subject: Re: [PATCH v5 3/8] net/gve: add support for device initialization
> 
> On 10/10/2022 11:17 AM, Junfeng Guo wrote:
> 
> >
> > Support device init and add following devops skeleton:
> >   - dev_configure
> >   - dev_start
> >   - dev_stop
> >   - dev_close
> >
> > Note that build system (including doc) is also added in this patch.
> >
> > Signed-off-by: Haiyue Wang <haiyue.wang at intel.com>
> > Signed-off-by: Xiaoyun Li <xiaoyun.li at intel.com>
> > Signed-off-by: Junfeng Guo <junfeng.guo at intel.com>
> 
> <...>
> 
> > --- /dev/null
> > +++ b/doc/guides/nics/gve.rst
> > @@ -0,0 +1,63 @@
> > +..  SPDX-License-Identifier: BSD-3-Clause
> > +    Copyright(C) 2022 Intel Corporation.
> > +
> > +GVE poll mode driver
> > +=======================
> > +
> > +The GVE PMD (**librte_net_gve**) provides poll mode driver support for
> > +Google Virtual Ethernet device (also called as gVNIC).
> > +
> 
> This is a virtual device, emulated in VM as PCI device, right?

Most likely yes. But I think this part is not public by Google.
(Correct me if I am wrong)

> If so what emulates it, I mean can we use QEMU for it?

Yes if the user can have a emulated gVNIC device or real HW that supports
gVNIC interface.

> And is there a kernel supported backend, as virtio has vhost?

I guess no if the back-end is not public

> 
> > +Current gVNIC is an alternative to the virtIO-based ethernet interface
> that can
> > +support higher network bandwidths such as the 50-100 Gbps speeds.
> 
> This is an alternative to virtio, and it would be good to document
> pros/cons of this device/approach, to help users to chose one or other.

I don't think it's good to compare these two. It's just two virtual interface,
I don't see strong analysis to prove which one is better.

Like if you use Google cloud, you use gVNIC. Use other cloud that uses virtio,
choose virtio.

> 
> Is "support higher network bandwidths" means this device is faster than
> virtio? Is there any performance report?
> Aren't there any other notable difference?

If we want to leave such description, I agree with Ferruh that we need to give
some evidence.

But in my understanding, they are just two similar virtual interfaces. One has
public standard, one is google-specific. Users need to use one of them when they
choose to use one cloud service.

Thanks,
Chenbo

> 
> I think better to document as much as possible, cc'ed more virtio people.
>