Re: Converting Ada Tasks To VxWorks Tasks?

[Ted Dennison <dennison@telepath.com>]

In article <r9CJ4.203$d21.25012@elnws01>,
  "Michael Hartsough" <Michael-Hartsough@mediaone.net> wrote:

> I've been vilified by the powers-that-be for making this particular
> program multi-tasking. In "our shop" the only way to implement a
> real-time system is by employing a cyclic-executive.

I've found a lot of places that do real-time work are conservative in
the extreme about this kind of thing. I think a large part of the reason
is that the job tends to require a lot of domain-specific knowledge that
has nothing to do with software engineering (eg: Engines, Avionics).
People who have that knowledge aren't nessecarily good s/w engnieers
(some are). But if they have one way of scheduling that's always worked
in the past and they know how to deal with, their goal in life is to
plunk down systems as close to that as possible from now on.

I discovered this myself the hard way when I tried creating a new
scheduler for a simulator. My first cut with everyone doing "delay
until" and no central scheduler, no-one would accept. The problem was it
did not rigidly constrain the order that tasks at the same priority ran.
I thought of that as an advantage, because you could plunk in extra
processors transparently to boost performance. But the domain engineers
always wrote their code assuming that model X ran to completion just in
front of them, and model Y will run to completion just after them. They
don't have to worry about synchornization with higher priority tasks
because they copy all the data they need from them into locals up front,
theoreticly before that higher-priority task has a chance to start
another iteration. They don't know any other way to write it, and
talking about other ways just scares them.

> Forgive me for blowing off some steam. I spent 12 years being a
> student of Ada, and now I'm being "retrained" to be a good little
> C++ developer. My career, as I knew it, has been destroyed by this

I myself spent 11 years at GE/Martin Marietta/Lockheed Martin. Believe
me, 11 years is a long time at a single company these days. C++ isn't
nessecarily a bad skill to learn at your company's expense. But if some
idiot over your head decides to take you up as their pet punching bag,
that's a really bad scene, and you can't do a damn thing about it (I've
been there too). They'll eventually reap what they sow, but that will
only be a small satisfaction to everyone else working there. As you
touched on before, Ada developers are in demand. Sometimes its time to
fish, and sometimes its time to cut bait...

--
T.E.D.

http://www.telepath.com/~dennison/Ted/TED.html


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