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Scheduler bug?



Leon Pollak wrote:
> On Sunday May 10 2009, Joel Sherrill wrote:
> > So they are OK with changing the hardware clock on a tested unit and
> > invalidating all testing but not upgrading the software. Any change on
> > a validated system is a change.
> Well, Korean AirForce - are not ordinary people...:-)
> May be I do not know everything - this is what I was told...
>
>
Any flight, military or space user is cautious. :)
>
>
> > We will have to use the collective RTEMS memory on this one. I recall
> > a bug that does sound like this.
> >
> > 2005-08-17 Andrew Sinclair <Andrew.Sinclair at elprotech.com
> > <mailto:Andrew.Sinclair at elprotech.com>>
> >
> > PR 807/rtems
> > * rtems/src/timerfireafter.c, rtems/src/timerserverfireafter.c,
> > score/src/watchdoginsert.c: Tighten critical section checks on an ISR
> > using the same timer being inserted by a lower priority ISR or
> > interupt task.
> >
> >
> > Does this sound like it? It was fixed in 4.6.4 (not 4.6.2)
> Hmm... Well.... I don't know... May be yes...
>
>
:-D
>
>
> > This only impacted 3 files so is no more of a change than increasing the
> > clock frequency.
> Joel, excuse me, I am not sure, I understand...
> Do you say, that increasing clock frequency, for example, to 10ms per 
> tick, will solve the problem and not make it less probable?
>
>
No.  IMO the bug either is or is not tripped in an application.  if you
shift the timing either way, you could trip it.  My guess is that
making the clock tick longer would decrease the probability since
you are having fewer ticks overall and less chance of a tick occurring
while a watchdog is being scheduled.

Does that make sense at all?
>
>
> > How is it OK to (*&% with the hardware and not with the
> > software.
> > Change is (*^ change.
> You are right.
> I suppose that they were doing some kind of "stress test". But I 
> really do not know.
>
>
And you are the only thing stressed right now. LOL!

>
> Really thanks!
> -- 
> Leon
>
>