Fusion and proc-adeos

Philippe Gerum rpm at xenomai.org
Tue Jan 18 09:06:17 CET 2005


On Tue, 2005-01-18 at 08:58, Philippe Gerum wrote:
> On Mon, 2005-01-17 at 18:19, Max Krasnyansky wrote:
> > Hi Philippe,
> > 
> > > printf() causes the calling thread to switch to secondary mode (i.e.
> > > priority-boosted Linux scheduling + irq shield) due to the write syscall
> > > it ends up issuing, then the display task switches back to primary (i.e.
> > > RTAI scheduling) when suspending on the RTAI semaphore.
> > > 
> > > Actually, the bug was not triggered by the write syscall but in fact by
> > > the rt_timer_ticks2ns() calls appearing in the printf() arglist. I've
> > > found the real culprit in the Adeos patch.
> > > 
> > > 
> > >>>other good news is that such delay induced by printf() seems bounded,
> > >>>even if unacceptable. More later, hopefully with a fix.
> > >>> 
> > >>>
> > >>
> > >>Would that mean that the execution time of printf() is bounded,
> > >>or that it is not a priority inversion but some other bug?
> > >>
> > > 
> > > 
> > > The bug was due to some hw IRQ mask being spuriously reasserted during
> > > the Adeos syscall interception (e.g. rt_timer_ticks2ns), but it was
> > > reverted by a common operation shortly after, causing some unpreemptible
> > > execution window, but not long enough to be spotted until you had the
> > > good idea to use different stress tests than I did :o)
> > 
> > Do you have new Adeos patch then ? ;-)
> 
> I'm validating it with the help of Takis. The changes are few but
> critical, so I want to stress the new patch on various setups before
> releasing it. It should be available in a day or two.

This said, everything is already in the Adeos CVS for public consumption
if you want to give it a try, but it has not been produced as an
individual patch yet.

> 
> > 
> > Max
> > 
> > _______________________________________________
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-- 

Philippe.





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