[Xenomai] Reading /proc/xenomai/stat causes high latencies

[Jeroen Van den Keybus]

> Do you get the same behaviour if you only enable the tracer after loading
> the xeno_native module?

Yes. but I just found out that the intel_idle driver option is causing
the stalls. Limiting to C1 state (using intel_idle.max_cstate=1)
apparently isn't cutting it and other nasty things must be happening
in this driver. After turning it off, the random stalling stopped.
Good.

Apart from that, I somehow managed to stop the high latencies from
occurring, I then saved the .config and then double-checked that (by
turning it off again) turning _on_ 'Run-time PM core functionality'
had solved the problem.

Surprisingly, the latencies are high again. But even with the stored
.config I have not been able to recreate the situation with tracer off
and normal latencies when reading xenomai/stat.


Jeroen.