Re: [Xenomai-core] ... the rt-preempt patch once been in fusion

[Philippe Gerum <rpm@xenomai.org>]

Hannes Mayer wrote:
> Hi all!
> 
> Well, subject says almost all.
> I remember there has been an effort to make a fusion/rt-preempt
> patch conglomerate back then.
> I'm just curious (as I've just been toying with the Molnar
> patch) - has that thing been dropped in xeno completely ?
> 

Clearly not, it is still on the project's agenda, but PREEMPT_RT has been too much 
of a moving target recently, not to speak of the vanilla 2.6 kernel itself. Even 
if Xeno's core has not changed in the same proportions, a large refactoring has 
taken place for 2.1 though.

Additionally, PREEMPT_RT's infrastructure has evolved a lot since Xeno was first 
ported over such kernel, and the way to interface both sub-systems likely needs to 
be re-thought. This combo cannot be done overnight, but I think that we are 
getting close to point where it would be possible to rework on this issue.

This work is likely going to start by a test campaign evaluating PREEMPT_RT's and 
Xeno's nucleus performances in a series of simple and relevant test cases over 
different ranges of platforms, so that we could measure up to which point (and 
under which condition) the real-time spectrum would be widened by using a 
combination of both.

-- 

Philippe.