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

[Cleber Rosa]

On Thu, Sep 19, 2019 at 01:14:50PM -0400, Cleber Rosa wrote:
> 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
>

What if we tag tests like this as "knownbug" (or a better name),
disabling execution by default?

- Cleber.

> Cheers,
> - Cleber.
> 
> > Thanks,
> > 
> > Phil.
> >