[Ksummit-discuss] Fwd: Rough notes from testing unconference

[Grant Likely]

On 23 Aug 2014 09:12, "Fengguang Wu" <fengguang.wu at intel.com> wrote:
>
> Hi all,
>
> Sorry the conversation went too fast for me to jump in.
> Hopefully it's not too late to have the below inputs.

Absolutely! There's a lot of things we talked about and all of the
topics are still up for discussion.

>
> On Fri, Aug 22, 2014 at 09:19:27AM -0500, Grant Likely wrote:
> > Rough notes from the Testing discussion during the workshop day of
> > Kernel Summit. Big thanks to Paul McKenney for writing all of this
> > down.
> >
> > g.
> >
> > Testing session (unconference)
> >
> > o       In-kernel or out of kernel?  Bisection?  Can do either way,
> >         one approach is to have two clones of the git tree, and another
> >         is to "git checkout" a specific version of the tools directory.
>
> Yes. What I do when bisecting scripts/coccinelle static check errors
> is to copy that directory out to some temp dir and use it as the
> stable version to run.
>
> > o       Levels of tests:  1) get a login prompt, 2) kselftest.
> >
> > o       Should we have specified userspace?  No, quickly gets into
> >         the distribution-building business.
>
> FYI, in lkp-tests, "bin/setup-local job.yaml" does all the necessary
> download, build, .deb creation and installation that's required for
> running the given job file. Its source code is at
>
> https://git.kernel.org/cgit/linux/kernel/git/wfg/lkp-tests.git
>
> mmtests and autotest has similar installation capabilities.

I'll take a look at those, thanks.

>
> > o       Will Deacon: Can script using busybox, inittab, and so on.
> >         Can run trinity on such a setup.
> >
> > o       Ted: Would be nice if other test frameworks built on top of
> >         kselftest.  Therefore kselftest should not make any asssumptions.
> >
> > o       Shua: Goal of kselftest isn't to create something new, but
> >         rather to gather up what we already have.
> >
> > o       Ted: Much of the code in tools/testing/selftest is unit tests
> >         for a tiny part of the kernel.  These don't really belong
> >         in LTP.
> >
> > o       Olof: Let's not reinvent the test-infrastructure wheel.
> >
> > o       Aneesh: Autotest.  Others: Lots of such tests, but lots of
> >         different ones that are relatively difficult to set up.
> >
> > o       Paul: Don't need rootfs.  rcutorture runs out of initrd.
> >
> > o       Olof: Often easier just to write a script.
> >
> > o       Ted: If we are going to lightweight, need to focus on kernel
> >         unit tests.
> >
> > o       What kind of tool can we depend on?  Busybox?  Just busybox,
> >         has everything it needs.  (This means scripting must be in
> >         dash.)
> >
> > o       Arnd: klibc has its own set of binaries, cannot support
> >         busybox.  Need libc.
> >
> > o       Josh: Only C and standard C library supported.
>
> lkp-tests currently depends on ruby to turn a job file into execution.
> However it could be converted to shell script. Then there comes an
> interesting question: will that make lkp-tests eligible for an
> out-of-tree kselftest?

I think we still want kselftest to live in tree. The issue here I
think is what is the simplest possible environment on the target. I
want to be able to cross build a really simple initrd that works for
any architecture that Linux supports. This gets test coverage out to
the less common architectures like microblaze.

I want to avoid c++, ruby, python, etc. Simply because it brings in a
lot of dependencies and things that can break. Shell script isn't a
problem.

For the simple rootfs that I'm trying to build, we can simply exclude
any tests that require extra libraries or interpreters. Anyone needing
something more complete should bring in a proper distro.

>
> > o       Paul:  Host or guest?
> >
> > o       Discussion: apparently need both.  Assume full-fledged distro
> >         on host, minimal on guest/target.  UART, retrieve a file.
> >         Some targets don't have persistent mass storage.
> >
> > o       Grant:  Needs to work on separate hardware, on qemu, on
> >         fast models.
> >
> > o       Need stdio output, input optional (some tests take input
> >         from kernel boot parameters.)
>
> Same here: the lkp-tests post-processing scripts work on stdio output
> of its test cases.
>
> > o       How to parse success or failure?  How to know what to ignore?
> >         Ted: What are high-level requirements rather than low-level
> >         implementation?  Need host to easily parse the information
> >         from the target on the host.
> >
> > o       Mauro: Need something for performance tests as well.
>
> lkp-tests is designed for performance tests.
>
> LKP = Linux Kernel Performance.
>
> In fact it runs every workload as performance/power tests, including
> the functionality tests. For example, yesterday LKP reported an ext4
> performance improvement when running xfstests:
>
>         Re: [ext4] 71d4f7d0321: -49.6% xfstests.generic.274.seconds
>         https://lkml.org/lkml/2014/8/21/726
>
> > o       Ted: Group the tests.  "Quick" group.  Groups associated with
> >         given function (e.g., suspend-resume).  Have profiles based
> >         on types of tests needed and time allotted.
> >
> > o       Josh: Add test types to the MAINTAINERS file.
> >
> > o       Tim: Requirements around cross-building?  People make their
> >         own?  We supply some in-tree?  We supply pointers to known
> >         good cross-build toolchains?  Grant: "Yes".
> >
> > o       Tim:  The need is to enable people who have never cross-built
> >         in their life to successfully cross-build and test with
> >         minimal effort.
>
> Sorry I may missed some background: given the ktest and aiaiai tools
> to help with cross-builds, what's the gap that we are discussing here?

Cross building the kernel isn't the problem. That's easy. Getting a
rootfs and the tests into the rootfs can be hard, depending on the
platform (a problem for some embedded targets).

ktest depends on a rootfs from elsewhere. I'm only mildly familiar
with aiaiai, but it appears to be the same situation. The gap I see is
the ability to cross compile the kselftest test cases and the ability
to create a rootfs including the test cases for any architecture. A
tool to solve that problem should be usable by both ktest and aiaiai.

>
> > Next steps:  Grant to send call for volunteers for various efforts
> >         to ksummit-discuss, interested people to reply.
>
> We have a team behind lkp-tests actively running tests for all kernel
> git trees we are aware of. We look forward to cooperate with everyone
> to make it better at catching upstream regressions. Any tests you
> would like to keep running for your subsystem, please let me know.

That would be great. What architectures are you currently testing on?

> Performance/power tests are in particular suitable for being added
> into lkp-tests -- it has very descriptive job file for running a workload
> with different parameter sets. Together with elaborate statistics
> collection and comparison capabilities, it allows people to catch
> subtle changes between different kernels/kconfigs/test parameters.
>
> Thanks,
> Fengguang