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

[Maciej Fijalkowski <maciej.fijalkowski@intel.com>]

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.

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