Re: Ada Embedded Systems Efficiencies

[bashford@srs.loral.com (Dave Bashford)]

I'm jumping in a little late with my experience, so I don't have the
original article to quote.  What I would like to address is the subject
of optimizing on the micro/macro level.

I was brought onto a R/T graphics program that had been "optimized" at
the micro level in order to implement a certain feature. The problems
though were that graphics hardware doubles in speed every 6 months
(more or less :-) and requirements change every 3.8ms. It was
eventually decided that the sacrifices made to implement that one
feature were too costly and what we really needed was higher update
rates. In order to accomplish this we needed to optimize at the highest
levels of our program which was not possible because of the tightly
coupled nature of the micro-optimizations. We were not able to take
advantage of the new hardware they kept throwing at the problem.

After many months, I convinced management that we should scrap the
system and start over with the experience and requirements that had
been learned from the past (a S/W engineer's dream !). Eight months
later (the original program had been going on for four years) we had a
new system that was running _many_ times faster, was infinitely easier
to maintain (the requirements are still changing), and now has the
original "feature" implemented without the original sacrifices.

I believe, like many others, that the compilers are much better at
micro-level optimizations; that requirements are _never_ static; and that
"optimizations" that tighten coupling are extremely costly in the long
run (if they work at all).
-- 

db
bashford@srs.loral.com (Dave Bashford, Sunnyvale, CA)