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From: "Tassilo v. Parseval" <tassilo.von.parseval@rwth-aachen.de>
Newsgroups: comp.lang.ada
Subject: Re: Isn't this in favour of Ada??
Date: Mon, 25 Jul 2005 11:48:25 +0200
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Also sprach Pascal Obry:

> "Alex R. Mosteo" <devnull@mailinator.com> writes:
>
>> OpenMP is pushing hard. At least I heard of it a lot, and seems to be pretty
>> standard when it comes to multithreading with C/C++. This edge in Ada may be
>> very well already lost.
>
> Have you looked at an OpenMP C++ enabled application ? OpenMP is a quite
> intrusive technology (adding lot of directives in comment) this makes the
> code again less readable. I agree that OpenMP is pushing hard, I'm sure it
> will gain a very good part of the market... this is just sad when you know the
> Ada tasking model. We can also talk about MPI compared to the distributed
> annex :(

I don't think that Ada tasks and MPI are comparable. MPI is mainly used
in the fields of supercomputing. You would certainly not use it as a
fork or threads replacement (incidentally, the 1.x standard of MPI did
not allow to create processes dynamically) because it would just be too
painful.

On the other hand it offers things not present in Ada tasks. MPI has its
own datatypes that allow you to specify in detail which parts of a
data-structure to send to another process, where the appropriate
conversions are done by MPI's pack routines. If you have a matrix with
rank 100,000 you don't want to share it all and in Ada you'd explicitely
have to take precautions against that.

Furthermore, MPI allows you to write a program that does a calculation
in parallel on your computer and, say, NEC's earth simulator because
data-exchange between processors can happen over TCP/IP. So MPI really
is a way to distribute one application across a huge distributed system
involving workstations that can be anywhere on the internet.

Also, there are MPI bindings for Ada which wouldn't be the case if those
two had the same niches in mind.

Tassilo
-- 
use bigint;
$n=71423350343770280161397026330337371139054411854220053437565440;
$m=-8,;;$_=$n&(0xff)<<$m,,$_>>=$m,,print+chr,,while(($m+=8)<=200);