Re: [dpdk-dev] KNI alternatives

[Igor Ryzhov <iryzhov@nfware.com>]

On Wed, Jan 13, 2021 at 8:10 PM Stephen Hemminger <
stephen@networkplumber.org> wrote:

> Last time I tried.
> Virtio user was as fast as KNI and consumed less cpu. Was seeing 10mpps
> Tap was much slower. Like 1mpps.
>
> Vpp uses virtio user.
>
> Sorry for top post. Only have phone internet
>
> On Wed, Jan 13, 2021, 9:06 AM Thomas Monjalon <thomas@monjalon.net> wrote:
>
> > Hi,
> >
> > As discussed today in the techboard meeting, KNI has probably
> > better alternatives today without using an out-of-tree module.
> > Virtio-user is a good candidate to replace KNI.
> > What is the performance of TAP?
> > Is there a way to leverage af_packet, af_xdp, or even pcap interfaces?


Performance is not the only question. The advantage of KNI we are currently
using is
the ability to control the DPDK interfaces by the kernel.
For example, to implement bonding in the DPDK application, it is possible
to create KNI
pair for each physical interface, create a bond interface in Linux over
those KNI interfaces
and just pass LACP packets between the app and the kernel. The kernel
itself will control
MACs, MTU, etc. of underlying interfaces. AFAIK it's not possible with
virtio-user or tap.
Am I wrong?


>

>
> > In order to avoid using the KNI out-of-tree module,
> > we should make the librte_kni compatible with an other interface.
> > The big plan is then to move the KNI module out of the main DPDK repo,
> > as we did for igb_uio.
> >
> > The first step of this plan might be to document pros & cons
> > of the KNI alternatives inside the KNI documentation:
> >         https://doc.dpdk.org/guides/prog_guide/kernel_nic_interface.html
> >
> > As a start, this doc should be better referenced:
> >
> > https://doc.dpdk.org/guides/howto/virtio_user_as_exceptional_path.html
> >
> > Note: I won't do this update myself, so feel free to step up!
> > Thanks
> >
> >
> >
>