Re: Problems with MIPS Malta SSH tests in make check-acceptance

[Cleber Rosa <crosa@redhat.com>]

On Thu, Sep 19, 2019 at 07:00:49PM +0200, Philippe Mathieu-Daudé wrote:
> On 9/19/19 6:56 PM, Cleber Rosa wrote:
> > On Wed, Sep 18, 2019 at 09:14:58PM -0400, Cleber Rosa wrote:
> >> On Wed, Sep 18, 2019 at 05:16:54PM +1000, David Gibson wrote:
> >>> Hi,
> >>>
> >>> I'm finding make check-acceptance is currently useless for me as a
> >>> pre-pull test, because a bunch of the tests are not at all reliable.
> >>> There are a bunch which I'm still investigating, but for now I'm
> >>> looking at the MIPS Malta SSH tests.
> >>>
> >>> There seem to be at least two problems here.  First, the test includes
> >>> a download of a pretty big guest disk image.  This can easily exhaust
> >>> the 2m30 timeout on its own.
> >>>
> >>
> >> You're correct that successes and failures on those tests depend
> >> largely on bandwith.  On a shared environment I used for tests
> >> the download of those images take roughly 400 seconds, resulting
> >> in failures.  On my own machine, around 60, and the tests pass.
> >>
> >> There's a conceptual and conflicting problem in that the environment
> >> for tests to run should be prepared beforehand.  The conflicting
> >> solutions can be:
> >>
> >>  * extensive bootstrapping of the test execution environment, such
> >>    as the installation of guests from ISOs or installation trees, or
> >>    the download of "default" images wether the tests will use it or
> >>    not (this is what Avocado-VT does/requires)
> >>
> >>  * keeping test assets in the tree (Avocado allows this if you have
> >>    a your_test.py.data/ directory), but it's not practical for large
> >>    files or files that can't or shouldn't be redistributed
> >>
> >>> Even without the timeout, it makes the test really slow, even on
> >>> repeated runs.  Is there some way we can make the image download part
> >>> of "building" the tests rather than actually running the testsuite, so
> >>> that a) the test themselves go faster and b) we don't include the
> >>> download in the test timeout - obviously the download speed is hugely
> >>> dependent on factors that aren't really related to what we're testing
> >>> here.
> >>>
> >>
> >> On Avocado version 72.0 we attempted to minimize the isse by
> >> implementing a "vmimage" command.  So, if you expect to use Fedora 30
> >> aarch64 images, you could run before your tests:
> >>
> >>  $ avocado vmimage get --distro fedora --distro-version 30 --arch aarch64
> >>
> >> And to list the images on your cache:
> >>
> >>  $ avocado vmimage list
> >>
> >> Unfortunately, this test doesn't use the vmimage API.  Actually that
> >> is fine because not all test assets map nicely to the vmimage goal,
> >> and should keep using the more generic (and lower level) fetch_asset().
> >>
> >> We're now working on various "asset fetcher" improvements that should
> >> allow us to check/cache all assets before a test is executed.  Also,
> >> we're adding a mode in which the "fetch_asset()" API will default to
> >> cancel (aka SKIP) a test if the asset could not be downloaded.
> >>
> >> If you're interested in the card we're using to track that new feature:
> >>
> >>   https://trello.com/c/T3SC1sZs/1521-implement-fetch-assets-command-line-parameter
> >>
> >> Another possibility that we've prototyped, and we'll be working on
> >> further, is to make a specific part of the "test" code execution
> >> (really a pre-test phase) to be executed without a timeout and even be
> >> tried a number of times before bailing out and skipping the test.
> >>
> >>> In the meantime, I tried hacking it by just increasing the timeout to
> >>> 10m.  That got several of the tests working for me, but one still
> >>> failed.  Specifically 'LinuxSSH.test_mips_malta32eb_kernel3_2_0' still
> >>> timed out for me, but now after booting the guest, rather than during
> >>> the image download.  Looking at the avocado log file I'm seeing a
> >>> bunch of soft lockup messages from the guest console, AFAICT.  So it
> >>> looks like we have a real bug here, which I suspect has been
> >>> overlooked precisely because the download problems mean this test
> >>> isn't reliable.
> >>>
> >>
> >> I've schedulled a 100 executions of `make check-acceptance` builds, with
> >> the linux_ssh_mips_malta.py tests having a 1500 seconds timeout.  The
> >> very first execution already brought interesting results:
> >>
> >>  ...
> >>  (15/39) /home/cleber/src/qemu/tests/acceptance/linux_ssh_mips_malta.py:LinuxSSH.test_mips_malta32eb_kernel3_2_0: PASS (198.38 s)
> >>  (16/39) /home/cleber/src/qemu/tests/acceptance/linux_ssh_mips_malta.py:LinuxSSH.test_mips_malta64el_kernel3_2_0: FAIL: Failure message found in console: Oops (22.83 s)
> >>
> >> I'll let you know about my full results.  This should also serve as a
> >> starting point to a discussion about the reliability of other tests,
> >> as you mentioned before.
> > 
> > Out of the 100 executions on a ppc64le host, the results that contain
> > failures and errors:
> > 
> > 15-/home/cleber/src/qemu/tests/acceptance/linux_ssh_mips_malta.py:LinuxSSH.test_mips_malta32eb_kernel3_2_0
> >   - PASS: 92
> >   - INTERRUPTED: 4
> >   - FAIL: 4
> > 16-/home/cleber/src/qemu/tests/acceptance/linux_ssh_mips_malta.py:LinuxSSH.test_mips_malta64el_kernel3_2_0
> >   - PASS: 95
> >   - FAIL: 5
> > 
> > FAIL means that self.fail() was called, which means 'Oops' was found
> > in the console.  INTERRUPTED here means that the test timeout kicked
> > in, and I can back David's statements about soft lockups.
> > 
> > Let me know if anyone wants access to the full logs/results.
> 
> Can you check if the FAIL case are this bug please?
> 
> https://bugs.launchpad.net/qemu/+bug/1833661
>

Yes, the errors do match.  I posted an updated there:

  https://bugs.launchpad.net/qemu/+bug/1833661/comments/3

Cheers,
- Cleber.

> Thanks,
> 
> Phil.
>