Re: Tasking performance between Ada83 and Ada95

[pascmartin@aol.com (PascMartin)]

Robert Dewar wrote:

"That's my guess too. I very much doubt that the Alsys World compiler on
  HPUX used system level threads, and I also guess that the
  version of GNAT on HPUX is probably using DCE threads.
  So the comparison is completely meaningless."

I don't agree. Let me elaborate. First, a few comments:

 - to my knowledge there is _no_ thread support in the HP-UX kernel (9
months
   ago..).
 - the DCE thread library is an user-level thread simulation (same
comment).
 - the AdaWorld product use "proprietary" user-level thread simulation,
   built into the Ada runtime, and (obsessively) optimized for it.

So far, considering respective features of these two runtimes, I see no
difference. Both are switching tasks at the same user level. Both will
have
the same problems regarding blocking IOs, both will never take benefit of
multiprocessing, etc..

Back to the point, can you compare a bicycle and a Ford Mustang?. No,
of course.. Robert you should practice bicycle more often, for me I can
tell
the difference when I use one or the other :-) (BTW, bicycle enhance
breathing).
What I want to demonstrate is: if the benchmark reflects the user's need,
then
the benchmark is good. It does not matter what products are compared, as
all Ada compilers implement the same thing: the Ada language. Don't they ?

If there is a better runtime for GNAT on HP-UX, this is a good time to
disclose
it. If there is none, the comparison seems valid to me.

It is true Ada95 ATC is a major constraint for runtime developpers. As
robustness is critical, especially in the first releases of a product, I
expect
most Ada95 runtimes to take a hit compare to Ada83 ones (1). Beside that,
ATC is so complicated that most (sane) people will probably avoid using
it.
My conclusion is: some Ada95 new features could have been left on
the side; they are appealing to a minority, and appaling to the others.

To conclude, if some program has to be developped for the real world, and
Ada83 is good enough, why not selecting AdaWorld?. When Ada95 (and
GNAT) will have been well optimized, or when HP will have released the
1 GHz HPPA workstation (which ever come first), it will be time to switch.

BTW, I must disclose that I have been working in Alsys for more years that
I want to admit..

(1) except for some implementation details. The ObjectAda runtime includes
a secondary stack design that is refreshingly efficient. Tucker Taft brain
child..

Pascal.