Re: [PATCH RFC 10/10] tests/migration-tests: Add test case for responsive CPU throttle

[Peter Maydell]

On Wed, 11 Sept 2024 at 22:26, Fabiano Rosas <farosas@suse.de> wrote:
> I don't think we're discussing total CI time at this point, so the math
> doesn't really add up. We're not looking into making the CI finish
> faster. We're looking into making migration-test finish faster. That
> would reduce timeouts in CI, speed-up make check and reduce the chance
> of random race conditions* affecting other people/staging runs.

Right. The reason migration-test appears on my radar is because
it is very frequently the thing that shows up as "this sometimes
just fails or just times out and if you hit retry it goes away
again". That might not be migration-test's fault specifically,
because those retries tend to be certain CI configs (s390,
the i686-tci one), and I have some theories about what might be
causing it (e.g. build system runs 4 migration-tests in parallel,
which means 8 QEMU processes which is too many for the number
of host CPUs). But right now I look at CI job failures and my reaction
is "oh, it's the migration-test failing yet again" :-(

For some examples from this week:

https://gitlab.com/qemu-project/qemu/-/jobs/7802183144
https://gitlab.com/qemu-project/qemu/-/jobs/7799842373
https://gitlab.com/qemu-project/qemu/-/jobs/7786579152
https://gitlab.com/qemu-project/qemu/-/jobs/7786579155

-- PMM