Re: [PATCH] kunit: tool: Add list of all valid test configs on UML

[David Gow]

On Tue, May 3, 2022 at 6:37 AM Daniel Latypov <dlatypov@xxxxxxxxxx> wrote:
>
> On Fri, Apr 29, 2022 at 11:56 PM David Gow <davidgow@xxxxxxxxxx> wrote:
> >
> > It's often desirable (particularly in test automation) to run as many
> > tests as possible. This config enables all the tests which work as
> > builtins under UML at present, increasing the total tests run from 156
> > to 342 (not counting 36 'skipped' tests).
>
> Just to clear up potential confusion for others, I'll note that these
> aren't counting test cases.
> This is from kunit.py's output, so it counts each parameter from
> parameterized tests as "subtests."
>
> Copying my command from
> https://kunit-review.googlesource.com/c/linux/+/5249, one can use this
> to count the # of test cases.
> $ ./tools/testing/kunit/kunit.py run --kunitconfig=...
> --raw_output=kunit --kernel_args=kunit.action=list | egrep
> '^[a-z0-9_-]+\.[a-z0-9_-]+'
>
> I see this enabling a total of 260 test _cases_ (including skipped).
>
> The default (basically just CONFIG_KUNIT_ALL_TESTS=y) gives 192
> (including skipped).
>

Yup, that's definitely the case. I guess I still was thinking in KTAP
terms, where all subtests are effectively tests.

That being said, I do think the total (sub)test (including parameters,
etc) number is the one that's more visible: not only does kunit_tool
print it, but it's also what we've been using as our go to "number of
tests" generally.

> >
> > They can be run with:
> > ./tools/testing/kunit/kunit.py run
> > --kunitconfig=./tools/testing/kunit/configs/all_tests_uml.config
> >
> > This acts as an in-between point between the KUNIT_ALL_TESTS config
> > (which enables only tests whose dependencies are already enabled), and
> > the kunit_tool --alltests option, which tries to use allyesconfig,
> > taking a very long time to build and breaking very often.
> >
> > Signed-off-by: David Gow <davidgow@xxxxxxxxxx>
>
> Tested-by: Daniel Latypov <dlatypov@xxxxxxxxxx>
>
> Looks good to me, some small comments below.
>
> > ---
> >  .../kunit/configs/all_tests_uml.config        | 37 +++++++++++++++++++
> >  1 file changed, 37 insertions(+)
> >  create mode 100644 tools/testing/kunit/configs/all_tests_uml.config
> >
> > diff --git a/tools/testing/kunit/configs/all_tests_uml.config b/tools/testing/kunit/configs/all_tests_uml.config
> > new file mode 100644
> > index 000000000000..bdee36bef4a3
> > --- /dev/null
> > +++ b/tools/testing/kunit/configs/all_tests_uml.config
> > @@ -0,0 +1,37 @@
> > +# This config enables as many tests as possible under UML.
> > +# It is intended for use in continuous integration systems and similar for
> > +# automated testing of as much as possible.
> > +# The config is manually maintained, though it uses KUNIT_ALL_TESTS=y to enable
> > +# any tests whose dependencies are already satisfied. Please feel free to add
> > +# more options if they any new tests.
>
> missing: "enable"?
> "if they enable any new tests"
>
Whoops, I was switching from "there are any" to "if they enable any"
and clearly got distracted halfway through. :-)

> Hmm, should we state a preference for how heavy (time or
> resource-wise) tests should be?
> Because the comment says it's meant for automation, but I can imagine
> humans wanting to run it.
> (I'm completely fine with us not stating one, just throwing the idea
> out there for discussion)

I think we're probably okay with being a little bit lenient on test
times. The time_test_cases.time64_to_tm_test_date_range and similar
tests take quite a long time in some situations already (older hw,
running under some emulators), but is generally pretty close to
instant under most UML setups. Particularly given that not building
with allyesconfig already saves us many, many minutes of time.

>
> Currently, I get this with an incremental rebuild:
> Elapsed time: 141.627s total, 1.384s configuring, 136.175s building,
> 3.970s running
>
> But we do have tests on other arches that take ~30s to run (kfence),
> for example.
> Would such tests be candidates for inclusion in this file?
> Or is it only problematic when they start taking a couple minutes each?

I think we probably have to just play this by ear a bit (particularly
since how long something takes is dependent on more than the test
itself). Kfence seems (if you'll forgive the expression) on the fence,
to me. If something's much slower than kfence, I'd probably be
skeptical of including it, particularly if lots of such tests emerged.
But ultimately, the line here is "is this reasonable to run (a) in a
CI system, and (b) interactively". If it's consuming too many
resources on a shared system or the total testing time is more than
single-digits-minutes, we'd have to consider the value longer tests
are actually adding.

-- David

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