Re: [PATCH v8 bpf-next 00/14] mvneta: introduce XDP multi-buffer support

[Magnus Karlsson <magnus.karlsson@gmail.com>]

On Tue, Apr 27, 2021 at 8:28 PM Lorenzo Bianconi <lorenzo@kernel.org> wrote:
>
> [...]
>
> > 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.
> >
> > 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?
>
> Hi Magnus,
>
> Today I carried out some comparison tests between bpf-next and bpf-next +
> xdp_multibuff series on mvneta running xdp_rxq_info sample. Results are
> basically aligned:
>
> bpf-next:
> - xdp drop ~ 665Kpps
> - xdp_tx   ~ 291Kpps
> - xdp_pass ~ 118Kpps
>
> bpf-next + xdp_multibuff:
> - xdp drop ~ 672Kpps
> - xdp_tx   ~ 288Kpps
> - xdp_pass ~ 118Kpps
>
> I am not sure if results are affected by the low power CPU, I will run some
> tests on ixgbe card.

Thanks Lorenzo. I made some new runs, this time with i40e driver
changes as a new data point. Same baseline as before but with patches
[1] and [2] applied. Note
that if you use net or net-next and i40e, you need patch [3] too.

The i40e multi-buffer support will be posted on the mailing list as a
separate RFC patch so you can reproduce and review.

Note, calculations are performed on non-truncated numbers. So 2 ns
might be 5 cycles on my 2.1 GHz machine since 2.49 ns * 2.1 GHz =
5.229 cycles ~ 5 cycles. xdpsock is run in zero-copy mode so it uses
the zero-copy driver data path in contrast with xdp_rxq_info that uses
the regular driver data path. Only ran the busy-poll 1-core case this
time. Reported numbers are the average over 3 runs.

multi-buffer patches without any driver changes:

xdpsock rxdrop 1-core:
i40e: -4.5% in throughput / +3 ns / +6 cycles
ice: -1.5% / +1 ns / +2 cycles

xdp_rxq_info -a XDP_DROP
i40e: -2.5% / +2 ns / +3 cycles
ice: +6% / -3 ns / -7 cycles

xdp_rxq_info -a XDP_TX
i40e: -10% / +15 ns / +32 cycles
ice: -9% / +14 ns / +29 cycles

multi-buffer patches + i40e driver changes from Tirtha:

xdpsock rxdrop 1-core:
i40e: -3% / +2 ns / +3 cycles

xdp_rxq_info -a XDP_DROP
i40e: -7.5% / +5 ns / +9 cycles

xdp_rxq_info -a XDP_TX
i40e: -10% / +15 ns / +32 cycles

Would be great if someone could rerun a similar set of experiments on
i40e or ice then
report.

[1] https://lists.osuosl.org/pipermail/intel-wired-lan/Week-of-Mon-20210419/024106.html
[2] https://lists.osuosl.org/pipermail/intel-wired-lan/Week-of-Mon-20210426/024135.html
[3] https://lists.osuosl.org/pipermail/intel-wired-lan/Week-of-Mon-20210426/024129.html

> Regards,
> Lorenzo
>
> >
> > Thanks: Magnus
> >
> > > 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(-)
> > >
> > > --
> > > 2.30.2
> > >