Re: [PATCH] cirrus: don't run full qtest on macOS

[Thomas Huth <thuth@redhat.com>]

On 06/01/2021 12.41, Daniel P. Berrangé wrote:
> The Cirrus CI macOS build hosts have exhibited a serious performance
> degradation in recent months. For example the "qom-test" qtest takes
> over an hour for only the qemu-system-aarch64 binary. This is as much
> 20-40 times slower than other environments. The other qtests all show
> similar performance degradation, as do many of the unit tests.
> 
> This does not appear related to QEMU code changes, since older git
> commits which were known to fully complete in less than 1 hour on
> Cirrus CI now also show similar bad performance. Either Cirrus CI
> performance has degraded, or an change in its environment has exposed
> a latent bug widely affecting all of QEMU. Debugging the qom-test
> showed no easily identified large bottleneck - every step of the
> test execution was simply slower.
> 
> macOS builds/tests run outside Cirrus CI show normal performance.
> 
> With an inability to identify any obvious problem, the only viable
> way to get a reliably completing Cirrus CI macOS job is to cut out
> almost all of the qtests. We choose to run the x86_64 target only,
> since that has very few machine types and thus is least badly
> impacted in the qom-test execution.

Sad that we have to do this, but as long as we still can run the x86 qtests, 
that's certainly better than nothing.

Reviewed-by: Thomas Huth <thuth@redhat.com>