[Intel-wired-lan] [net-next PATCH 0/3] XDP for ixgbe

[Alexander Duyck]

On Sat, Feb 25, 2017 at 9:32 AM, John Fastabend
<john.fastabend at gmail.com> wrote:
> This series adds support for XDP on ixgbe. We still need to understand
> adjust head size requirement. If we can compromise at 196B (is this
> correct Alex?) then we can continue to use normal driver RX path and

In theory on x86 there is 192B of headroom we can reserve since shared
infor is only 320B.  That leaves us with 1536 for packet storage.

That said the current code is only reserving NET_SKB_PAD +
NET_IP_ALIGN as I hadn't taken into account the need for more headroom
than that when I did the ixgbe patches.  I'll try to submit a
follow-up patch for igb and ixgbe to update the padding.

> avoid having XDP codebase + normal codebase. This is a big win for
> everyone who has to read this code day to day and work on it. I
> suggest if more headroom is needed then it should also be needed in
> the normal stack case and we should provide a generic mechanism to
> build up more headroom. Plus we already have ndo_set_rx_headroom()
> can we just use this?
>
> If this series can get accepted then we have a series behind it to
> enable batching on TX to push TX Mpps up to line rates. The gist of
> the implementation is to run XDP program in a loop, collecting the
> action results in an array. And then pushing them into the TX routine.
> For a first gen this will likely abort if we get a XDP_PASS routine
> but this is just a matter of code wrangling and lazyness. It can be
> resolved.
>
> Future looking some improvements are needed, TX routines should take
> an array of packets if we believe long trains of packets will be on
> the RX ring inside a "processing window" (how many descriptors we
> handle per irq clean). Note with many queues on devices we can ensure
> this happens with flow director or even RSS in some cases.
>
> @Alex, please review. Look at patch 2/3 in paticular and let me know
> what you think about the trade-offs I made there w.r.t. num_xdp_queues

I'll try to get the set reviewed this weekend.

> ---
>
> John Fastabend (3):
>       ixgbe: add XDP support for pass and drop actions
>       ixgbe: add support for XDP_TX action
>       ixgbe: xdp support for adjust head
>
>
>  drivers/net/ethernet/intel/ixgbe/ixgbe.h         |   14 +
>  drivers/net/ethernet/intel/ixgbe/ixgbe_ethtool.c |   29 +
>  drivers/net/ethernet/intel/ixgbe/ixgbe_lib.c     |   85 ++++
>  drivers/net/ethernet/intel/ixgbe/ixgbe_main.c    |  439 ++++++++++++++++++++--
>  4 files changed, 511 insertions(+), 56 deletions(-)
>
> --
> Signature