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.

Hi Magnus,

thx for working on it. Assuming the fragmented part is only initialized/accessed
if mb is set (so for multi frame packets), I would not expect any throughput
degradation in the single frame scenario. Can you please share the i40e
support added by Tirtha?

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?

IIRC I did not get sensible throughput degradation on mvneta but I will re-run
the tests running an updated bpf-next tree.

Regards,
Lorenzo

Thanks: Magnus

quoted

Eelco Chaudron (4):
  bpf: add multi-buff support to the bpf_xdp_adjust_tail() API
  bpd: add multi-buffer support to xdp copy helpers
  bpf: add new frame_length field to the XDP ctx
  bpf: update xdp_adjust_tail selftest to include multi-buffer

Lorenzo Bianconi (10):
  xdp: introduce mb in xdp_buff/xdp_frame
  xdp: add xdp_shared_info data structure
  net: mvneta: update mb bit before passing the xdp buffer to eBPF layer
  xdp: add multi-buff support to xdp_return_{buff/frame}
  net: mvneta: add multi buffer support to XDP_TX
  net: mvneta: enable jumbo frames for XDP
  net: xdp: add multi-buff support to xdp_build_skb_from_fram
  bpf: move user_size out of bpf_test_init
  bpf: introduce multibuff support to bpf_prog_test_run_xdp()
  bpf: test_run: add xdp_shared_info pointer in bpf_test_finish
    signature

 drivers/net/ethernet/marvell/mvneta.c         | 182 ++++++++++--------
 include/linux/filter.h                        |   7 +
 include/net/xdp.h                             | 105 +++++++++-
 include/uapi/linux/bpf.h                      |   1 +
 net/bpf/test_run.c                            | 109 +++++++++--
 net/core/filter.c                             | 134 ++++++++++++-
 net/core/xdp.c                                | 103 +++++++++-
 tools/include/uapi/linux/bpf.h                |   1 +
 .../bpf/prog_tests/xdp_adjust_tail.c          | 105 ++++++++++
 .../selftests/bpf/prog_tests/xdp_bpf2bpf.c    | 127 ++++++++----
 .../bpf/progs/test_xdp_adjust_tail_grow.c     |  17 +-
 .../bpf/progs/test_xdp_adjust_tail_shrink.c   |  32 ++-
 .../selftests/bpf/progs/test_xdp_bpf2bpf.c    |   3 +-
 13 files changed, 767 insertions(+), 159 deletions(-)

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2.30.2