Re: ci: Follow-up CI patches

Hi,

On Wed, 4 Nov 2026 at 17:36, Andres Freund <andres(at)anarazel(dot)de> wrote:
>
> On 2026-11-04 11:28:02 +0300, Nazir Bilal Yavuz wrote:
> > Andres shared some CI patches in the 'Heads Up: cirrus-ci is shutting
> > down June 1st' thread [1]. Since this thread is already quite long, I
> > wanted to create a new thread for them.
>
> Thanks!

Here are two more follow-up patches; the other patches are unchanged.

First one (0007) upgrades the OS versions:

Ubuntu 24.04 -> Ubuntu 26.04
Windows 2022 -> Windows 2025
Macos 15 -> Macos 26 and Macports 2.10.1 -> 2.12.7

All tested and work correctly.

Second one (0008) uses parallel steps feature [1] in the
CompilerWarnings task. This feature helps run some steps in parallel
in the background. I tested a bit to find the best method for
parallelizing, from the commit message:

```
Different methods are tested with cold and warm compiler caches on a
four-core GitHub-hosted runner. Total CompilerWarnings job times are:

Cold Warm
Default 20m 56s 3m 57s
Parallel configure, sequential builds 19m 47s 3m 04s
Pairs of checks, ninja -j 2 18m 10s 3m 49s
All checks in parallel, ninja -j 1 15m 26s 2m 30s
All checks in parallel, default ninja jobs 17m 03s 3m 48s

- Parallel configure, sequential builds: Configure all seven checks
concurrently, then build them one at a time using Ninja’s default
concurrency.

- Pairs of checks, ninja -j 2: Run configuration and build in three
successive pairs with two Ninja jobs per check, then run the
remaining header check alone with default concurrency.

- All checks in parallel, ninja -j 1: Run all seven configure/build
sequences concurrently, limiting each Ninja invocation to one job.

- All checks in parallel, default Ninja jobs: Same as above but using
Ninja's default concurrency.

Based on this result, 'all checks in parallel, ninja -j 1' is selected.
```

I used $j = max($available_cpus / $parallel_jobs, 1) and that
calculates 1 since we have 4 CPU. I am not sure this is the right
method because if some jobs finish early and free up CPU resources,
other tasks will still use $j. However, this method is the fastest,
which I didn't expect it. So this one is used.

[1] https://docs.github.com/en/actions/reference/workflows-and-actions/workflow-syntax#example-running-steps-in-parallel

--
Regards,
Nazir Bilal Yavuz
Microsoft