Re: shared interrupts

On Tuesday 24 January 2006 12:21 am, Calin A. Culianu wrote:
> Well regular RT tasks run with interrupts enabled anyway.  They just
> pend linux interrupts until the RT system is idle.  The small RTLinux
> and real-time ISRs always get to run, even in RTLinux, RTAi, etc.  Not
> sure I agree with that design but that's the way it works.  At least
> that's my understanding.  Am I wrong?

My point is:

non rt device has interrupt->

shared pci interrupt asserted->

rt handler runs (does nothing)->

interrupt still asserted->

rt handler disabled until non rt device handler is run and interrupt line 
is no longer asserted

The only way I can see they could still guarantee any bound on latency is 
if they run the rt handler in a polling mode every N microseconds off of 
timer interrupts while the shared interrupt remains asserted.

-- 
Frank