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Date:   Mon, 11 May 2020 20:13:38 -0700
From:   Andrii Nakryiko <andrii.nakryiko@...il.com>
To:     John Fastabend <john.fastabend@...il.com>
Cc:     Lorenz Bauer <lmb@...udflare.com>,
        Jakub Sitnicki <jakub@...udflare.com>,
        Daniel Borkmann <daniel@...earbox.net>,
        Networking <netdev@...r.kernel.org>, bpf <bpf@...r.kernel.org>,
        Alexei Starovoitov <ast@...nel.org>
Subject: Re: [bpf-next PATCH 00/10] bpf: selftests, test_sockmap improvements

On Sat, May 9, 2020 at 7:55 AM John Fastabend <john.fastabend@...il.com> wrote:
>
> Andrii Nakryiko wrote:
> > On Tue, May 5, 2020 at 1:50 PM John Fastabend <john.fastabend@...il.com> wrote:
> > >
> > > Update test_sockmap to add ktls tests and in the process make output
> > > easier to understand and reduce overall runtime significantly. Before
> > > this series test_sockmap did a poor job of tracking sent bytes causing
> > > the recv thread to wait for a timeout even though all expected bytes
> > > had been received. Doing this many times causes significant delays.
> > > Further, we did many redundant tests because the send/recv test we used
> > > was not specific to the parameters we were testing. For example testing
> > > a failure case that always fails many times with different send sizes
> > > is mostly useless. If the test condition catches 10B in the kernel code
> > > testing 100B, 1kB, 4kB, and so on is just noise.
> > >
> > > The main motivation for this is to add ktls tests, the last patch. Until
> > > now I have been running these locally but we haven't had them checked in
> > > to selftests. And finally I'm hoping to get these pushed into the libbpf
> > > test infrastructure so we can get more testing. For that to work we need
> > > ability to white and blacklist tests based on kernel features so we add
> > > that here as well.
> > >
> > > The new output looks like this broken into test groups with subtest
> > > counters,
> > >
> > >  $ time sudo ./test_sockmap
> > >  # 1/ 6  sockmap:txmsg test passthrough:OK
> > >  # 2/ 6  sockmap:txmsg test redirect:OK
> > >  ...
> > >  #22/ 1 sockhash:txmsg test push/pop data:OK
> > >  Pass: 22 Fail: 0
> > >
> > >  real    0m9.790s
> > >  user    0m0.093s
> > >  sys     0m7.318s
> > >
> > > The old output printed individual subtest and was rather noisy
> > >
> > >  $ time sudo ./test_sockmap
> > >  [TEST 0]: (1, 1, 1, sendmsg, pass,): PASS
> > >  ...
> > >  [TEST 823]: (16, 1, 100, sendpage, ... ,pop (1599,1609),): PASS
> > >  Summary: 824 PASSED 0 FAILED
> > >
> > >  real    0m56.761s
> > >  user    0m0.455s
> > >  sys     0m31.757s
> > >
> > > So we are able to reduce time from ~56s to ~10s. To recover older more
> > > verbose output simply run with --verbose option. To whitelist and
> > > blacklist tests use the new --whitelist and --blacklist flags added. For
> > > example to run cork sockhash tests but only ones that don't have a receive
> > > hang (used to test negative cases) we could do,
> > >
> > >  $ ./test_sockmap --whitelist="cork" --blacklist="sockmap,hang"
> > >
> > > ---
> >
> > A lot of this seems to be re-implementing good chunks of what we
> > already have in test_progs. Would it make more sense to either extract
> > test runner pieces from test_progs into something that can be easily
> > re-used for creating other test runners or just fold all these test
> > into test_progs framework? None of this code is fun to write and
> > maintain, so I'd rather have less copies of it :)
>
> I like having its own test runner for test_sockmap. At leat I like
> having the CLI around to run arbitrary tests while doing devloping
> of BPF programs and on the kernel side.

Keeping them in separate binary is fine with me, but just wanted to
make sure you are aware of -t and -n options to test_progs? -t
test-substring[/subtest-substring] allows to select test(s), and,
optionally, subtests(s) by substring of their names. -n allows to do
selection by test/subtest numbers. This allows a very nice way to
debug/develop singular test or a small subset of tests. Just FYI, in
case you missed this feature.

>
> We could fold all the test progs into progs framework but because
> I want to keep test_sockmap CLI around it didn't make much sense.
> I would still need most the code for the tool.
>
> So I think the best thing is to share as much code as possible.
> I am working on a series behind this to share more code on the
> socket attach, listend, send/recv side but seeing this series was
> getting large and adds the ktls support which I want in selftests
> asap I pushed it. Once test_sockmap starts using the shared socket
> senders, receivers, etc. I hope lots of code will dissapper.
>
> The next easy candidate is the cgroup helpers. test_progs has
> test__join_cgroup() test_sockmap has equivelent.
>
> Its possible we could have used the same prog_test_def{} struct
> but it seemed a bit overkill to me for this the _test{} struct
> and helpers is ~50 lines here. Getting the socket handling and
> cgroup handling into helpers seems like a bigger win.

Test_progs is doing a bit more than just that. It's about 600 lines of
code just in test_progs.c, which does generic test
running/reporting/logging interception, etc. Plus some more in
test_progs.h. So I think sharing that "test runner base" could save
more code and allow more flexible test runner experience.

>
> Maybe the blacklist/whitelist could be reused with some refactoring
> and avoid one-off codei for that as well.
>
> Bottom line for me is this series improves things a lot on
> the test_sockmap side with a reasonable patch series size. I
> agree with your sentiment though and would propose doing those
> things in follow up series likely in this order: socket handlers,
> cgroup handlers, tester structure.

Yep, makes sense. I just wanted to make sure that this is on the table. Thanks!

>
> Thanks!
>
>
> >
> > >
> > > John Fastabend (10):
> > >       bpf: selftests, move sockmap bpf prog header into progs
> > >       bpf: selftests, remove prints from sockmap tests
> > >       bpf: selftests, sockmap test prog run without setting cgroup
> > >       bpf: selftests, print error in test_sockmap error cases
> > >       bpf: selftests, improve test_sockmap total bytes counter
> > >       bpf: selftests, break down test_sockmap into subtests
> > >       bpf: selftests, provide verbose option for selftests execution
> > >       bpf: selftests, add whitelist option to test_sockmap
> > >       bpf: selftests, add blacklist to test_sockmap
> > >       bpf: selftests, add ktls tests to test_sockmap
> > >
> > >
> > >  .../selftests/bpf/progs/test_sockmap_kern.h        |  299 +++++++
> > >  tools/testing/selftests/bpf/test_sockmap.c         |  911 ++++++++++----------
> > >  tools/testing/selftests/bpf/test_sockmap_kern.h    |  451 ----------
> > >  3 files changed, 769 insertions(+), 892 deletions(-)
> > >  create mode 100644 tools/testing/selftests/bpf/progs/test_sockmap_kern.h
> > >  delete mode 100644 tools/testing/selftests/bpf/test_sockmap_kern.h
> > >
> > > --
> > > Signature
>
>

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