Possible Xenomai 3 latency regression on arm64

Hi all,

it seems we got some >10% worst-case latency increase over the last
month with Xenomai head and 6.12 - that is at least the setup we use in
our long-running weekly test.

Tonight, the RPi4 test triggered by exceeding the configured limit of
150 µs [1]. About half a year ago, we were in 130 µs range with it [2].
x86 and beaglebone are apparently not seeing this change.

Those are preliminary numbers obtained by manually clicking around. Some
visualization of the final worst-case numbers over time would have been
more useful for this. Maybe someone has an idea how to transfer them
into a database or just a plain file from were we could render a gitlab
page or so. A trend analysis which already warns on constant increases
would be the next-but-one logical step.

But for now the question is if this is a real regression or just a shift
in how likely higher latencies became. Or was there some change in our
physical setup, possibly causing more thermal issues or something like
this now?

If it's a real software issue, what is causing this, the 6.12 kernel or
Xenomai 3 head? Anyone willing to dig into some more analysis, probably
first by retrying older runs?

Jan

[1] https://gitlab.com/Xenomai/xenomai-images/-/jobs/14848873648
[2] https://gitlab.com/Xenomai/xenomai-images/-/jobs/12189033381

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