Re: Realtime Ada Conferences

[lph@sei.cmu.edu (Larry Howard)]

In article <4j9j9f$620@hacgate2.hac.com> jts@ipld01.hac.com
(Jeff T. Stevenson) writes:

<snip>
>Is anything being done to allow Ada compiler vendors to 
>produce compilers that have task context switch times
>in the 20 us range?  It seems that most compiler vendors
>are not able to comply with the Ada83 tasking model
>and provide realtime context switching capabilities.

Yes, they're called faster computers. :-) Seriously, the
implication I got from what you said is that Ada compilation
systems without 20 usec context switching times do not provide
realtime context switching capabilities.  Many realtime
applications do not require this level of performance and are
nonetheless realtime.  "Realtime" implies to me predictable
timing behavior, and not some arbitrary level of performance.

>Ada 95 does not really solve the realtime problem because
>vendors are not forced to deliver the Ada 95 realtime
>extensions.

That vendors aren't forced to deliver an annex is precisely
the idea of annexes.  It's their targeted marketplace that
should determine whether a vendor supplies a given annex and
at what level of performance.  Besides, I'm only familiar with
one hard performance requirement in the Real-Time Systems
Annex, and that is for clock resolution, which incidentally is
20 usecs or better.  This certainly stands to affect task
periodicities, but not context switching times.

Am I missing something?
--
Larry Howard
Software Engineering Institute, Carnegie Mellon University
lph@sei.cmu.edu (NeXT Mail OK)      (412) 268-6397