Re: [PATCH bpf-next v2 00/15] selftests/xsk: speed-ups, fixes, and new XDP programs

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

On Tue, Jan 10, 2023 at 1:00 PM Maciej Fijalkowski
<maciej.fijalkowski@intel.com> wrote:
>
> On Wed, Jan 04, 2023 at 01:17:29PM +0100, Magnus Karlsson wrote:
> > This is a patch set of various performance improvements, fixes and the
> > introduction of more than one XDP program to the xsk selftests
> > framework so we can test more things in the future such as upcoming
> > multi-buffer and metadata support for AF_XDP. The new programs just
> > reuses the framework that all the other eBPF selftests use. The new
> > feature is used to implement one new test that does XDP_DROP on every
> > other packet. More tests using this will be added in future commits.
> >
> > Contents:
> >
> > * The run-time of the test suite is cut by 10x when executing the
> >   tests on a real NIC, by only attaching the XDP program once per mode
> >   tested, instead of once per test program.
> >
> > * Over 700 lines of code have been removed. The xsk.c control file was
> >   moved straight over from libbpf when the xsk support was deprecated
> >   there. As it is now not used as library code that has to work with
> >   all kinds of versions of Linux, a lot of code could be dropped or
> >   simplified.
> >
> > * Add a new command line option "-d" that can be used when a test
> >   fails and you want to debug it with gdb or some other debugger. The
> >   option creates the two veth netdevs and prints them to the screen
> >   without deleting them afterwards. This way these veth netdevs can be
> >   used when running xskxceiver in a debugger.
> >
> > * Implemented the possibility to load external XDP programs so we can
> >   have more than the default one. This feature is used to implement a
> >   test where every other packet is dropped. Good exercise for the
> >   recycling mechanism of the xsk buffer pool used in zero-copy mode.
> >
> > * Various clean-ups and small fixes in patches 1 to 5. None of these
> >   fixes has any impact on the correct execution of the tests when they
> >   pass, though they can be irritating when a test fails. IMHO, they do
> >   not need to go to bpf as they will not fix anything there. The first
> >   version of patches 1, 2, and 4 where previously sent to bpf, but has
> >   now been included here.
> >
> > v1 -> v2:
> > * Fixed spelling error in commit message of patch #6 [Björn]
> > * Added explanation on why it is safe to use C11 atomics in patch #7
> >   [Daniel]
> > * Put all XDP programs in the same file so that adding more XDP
> >   programs to xskxceiver.c becomes more scalable in patches #11 and
> >   #12 [Maciej]
> > * Removed more dead code in patch #8 [Maciej]
> > * Removed stale %s specifier in error print, patch #9 [Maciej]
> > * Changed name of XDP_CONSUMES_SOME_PACKETS to XDP_DROP_HALF to
> >   hopefully make it clearer [Maciej]
> > * ifobj_rx and ifobj_tx name changes in patch #13 [Maciej]
> > * Simplified XDP attachment code in patch #15 [Maciej]
>
> I had minor comments on last patch which you can take or not.
> From my side it is an ack for whole series:
>
> Acked-by: Maciej Fijalkowski <maciej.fijalkowski@intel.com>
>
> However you probably would like to ping Daniel against patch 7.
> Also, usage of printf vs ksft_print_msg seems sort of random throughout
> this series but it's not a big deal.

Yep, it has been more or less random from day one, unfortunately. I
will look into it for the next patch set of fixes.

> Thanks!
>
> >
> > Patches:
> > 1-5:   Small fixes and clean-ups
> > 6:     New convenient debug option when using a debugger such as gdb
> > 7-8:   Removal of unnecessary code
> > 9:     Add the ability to load external XDP programs
> > 10-11: Removal of more unnecessary code
> > 12:    Implement a new test where every other packet is XDP_DROP:ed
> > 13:    Unify the thread dispatching code
> > 14-15: Simplify the way tests are written when using custom packet_streams
> >        or custom XDP programs
> >
> > Thanks: Magnus
> >
> > Magnus Karlsson (15):
> >   selftests/xsk: print correct payload for packet dump
> >   selftests/xsk: do not close unused file descriptors
> >   selftests/xsk: submit correct number of frames in populate_fill_ring
> >   selftests/xsk: print correct error codes when exiting
> >   selftests/xsk: remove unused variable outstanding_tx
> >   selftests/xsk: add debug option for creating netdevs
> >   selftests/xsk: replace asm acquire/release implementations
> >   selftests/xsk: remove namespaces
> >   selftests/xsk: load and attach XDP program only once per mode
> >   selftests/xsk: remove unnecessary code in control path
> >   selftests/xsk: get rid of built-in XDP program
> >   selftests/xsk: add test when some packets are XDP_DROPed
> >   selftests/xsk: merge dual and single thread dispatchers
> >   selftests/xsk: automatically restore packet stream
> >   selftests/xsk: automatically switch XDP programs
> >
> >  tools/testing/selftests/bpf/Makefile          |   2 +-
> >  .../selftests/bpf/progs/xsk_xdp_progs.c       |  30 +
> >  tools/testing/selftests/bpf/test_xsk.sh       |  42 +-
> >  tools/testing/selftests/bpf/xsk.c             | 674 +-----------------
> >  tools/testing/selftests/bpf/xsk.h             |  97 +--
> >  tools/testing/selftests/bpf/xsk_prereqs.sh    |  12 +-
> >  tools/testing/selftests/bpf/xskxceiver.c      | 382 +++++-----
> >  tools/testing/selftests/bpf/xskxceiver.h      |  17 +-
> >  8 files changed, 308 insertions(+), 948 deletions(-)
> >  create mode 100644 tools/testing/selftests/bpf/progs/xsk_xdp_progs.c
> >
> >
> > base-commit: bb5747cfbc4b7fe29621ca6cd4a695d2723bf2e8
> > --
> > 2.34.1