> On Sun, Apr 18, 2021 at 6:18 PM Jesper Dangaard Brouer
> <bro...@redhat.com> wrote:
> >
> > On Fri, 16 Apr 2021 16:27:18 +0200
> > Magnus Karlsson <magnus.karls...@gmail.com> wrote:
> >
> > > On Thu, Apr 8, 2021 at 2:51 PM Lorenzo Bianconi <lore...@kernel.org>
> > > wrote:
> > > >
> > > > This series introduce XDP multi-buffer support. The mvneta driver is
> > > > the first to support these new "non-linear" xdp_{buff,frame}. Reviewers
> > > > please focus on how these new types of xdp_{buff,frame} packets
> > > > traverse the different layers and the layout design. It is on purpose
> > > > that BPF-helpers are kept simple, as we don't want to expose the
> > > > internal layout to allow later changes.
> > > >
> > > > For now, to keep the design simple and to maintain performance, the XDP
> > > > BPF-prog (still) only have access to the first-buffer. It is left for
> > > > later (another patchset) to add payload access across multiple buffers.
> > > > This patchset should still allow for these future extensions. The goal
> > > > is to lift the XDP MTU restriction that comes with XDP, but maintain
> > > > same performance as before.
> > [...]
> > > >
> > > > [0]
> > > > https://netdevconf.info/0x14/session.html?talk-the-path-to-tcp-4k-mtu-and-rx-zerocopy
> > > > [1]
> > > > https://github.com/xdp-project/xdp-project/blob/master/areas/core/xdp-multi-buffer01-design.org
> > > > [2]
> > > > https://netdevconf.info/0x14/session.html?tutorial-add-XDP-support-to-a-NIC-driver
> > > > (XDPmulti-buffers section)
> > >
> > > Took your patches for a test run with the AF_XDP sample xdpsock on an
> > > i40e card and the throughput degradation is between 2 to 6% depending
> > > on the setup and microbenchmark within xdpsock that is executed. And
> > > this is without sending any multi frame packets. Just single frame
> > > ones. Tirtha made changes to the i40e driver to support this new
> > > interface so that is being included in the measurements.
> >
> > Could you please share Tirtha's i40e support patch with me?
>
> We will post them on the list as an RFC. Tirtha also added AF_XDP
> multi-frame support on top of Lorenzo's patches so we will send that
> one out as well. Will also rerun my experiments, properly document
> them and send out just to be sure that I did not make any mistake.ack, very cool, thx > > Just note that I would really like for the multi-frame support to get > in. I have lost count on how many people that have asked for it to be > added to XDP and AF_XDP. So please check our implementation and > improve it so we can get the overhead down to where we want it to be. sure, I will do. Regards, Lorenzo > > Thanks: Magnus > > > I would like to reproduce these results in my testlab, in-order to > > figure out where the throughput degradation comes from. > > > > > What performance do you see with the mvneta card? How much are we > > > willing to pay for this feature when it is not being used or can we in > > > some way selectively turn it on only when needed? > > > > Well, as Daniel says performance wise we require close to /zero/ > > additional overhead, especially as you state this happens when sending > > a single frame, which is a base case that we must not slowdown. > > > > -- > > Best regards, > > Jesper Dangaard Brouer > > MSc.CS, Principal Kernel Engineer at Red Hat > > LinkedIn: http://www.linkedin.com/in/brouer > > >
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