Jan Kiszka wrote:

this is an experimental hack to open the non-rt priority levels of Linux
to Xenomai shadow threads, i.e. allow shadows to be scheduled under
SCHED_NORMAL when in secondary mode. The scenario are typical borderline
threads between RT and non-RT: they share a critical code path with RT
threads, maybe mutex protected, but they are mostly time-sharing threads
which do not need SCHED_FIFO for this.

The patch (be careful, quick-hack!) addresses the prio level 0 in the
ipipe patch, the nucleus/shadow subsystem, and the native skin. A quick
test with the attached demo showed the expected behaviour so far: no
lock-up during busy-waiting in secondary mode, prio-boost when holding
the lock (visible via /proc/xenomai/sched), no obvious side effects.

Any comments? Does this break other things in a subtle way?

Normally, the fixes that went in 2.1 regarding the internal synchronization of the thread hardening/relaxing services should allow this since we don't care anymore of the underlying Linux scheduling class. I'm queuing this patch for further testing, but I basically agree with its purpose, since it's another step toward deep integration with Linux. Thanks.



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