Re: Ada-friendly MPI

[Pascal Obry <pascal@obry.net>]

jtg <jtg77@poczta.onet.pl> writes:

> Errr... I should have said: job.

Ok.

> OK... If you write your program for MPI, you must run it with "mpirun"
> command in mpi-enabled environment. If you write your program for PVM,
> you must run it with "pvmrun" command in pvm-enabled environment. If you
> use Ada Distributed Annex, there must be a command that dispatches tasks
                                                                     ^^^^^
                                                                 job/partitions
> and establishes communication between them, and the environment itself
> must be configured for Ada Distribution Annex.

No. Job dispatching on the different nodes are handled by GLADE (the
implementation of Annex-E for GNAT). In fact, gnatdist (the equivalent to
gnatmake for building distributed program) can generate a script or Ada main
that will run/dispatch the different job/partitions on the different nodes.

Then the boot-partition (a module in one or more partition) is used to
initialized the distributed program. As you see MPI is far more low-level
than the Ada solution. And the good news is that you can run your Ada program
in a single computer (built with gnatmake) or in a distributed environment
(built with gnatdist) without changing a single line of Ada code.

Looks like magic, but it is not. It is in my opinion the right level of
abstraction to concentrate on your problem instead of low-level stuff.

> That's automatic only if you run it in the proper way and the environment is
> configured. For instance if you run MPI task with "pvmrun" or vice versa
> nothing will be done automatic.

As I said GLADE take care of that.

> How do you run Ada distributed programs? How are they dispatched to other
> nodes (processors/computers)? Is there a command like "adarun" (analogous
> to mpirun and pvmrun)?

As described above this is done by a generated script (shell or Ada).

> > Then use the same simple binding for Ada. If the binding is simple you
> > should be able to create the Ada counterpart without problem.
> I'm afraid I don't understand this.

I mean you can always create a binding to the MPI API for Ada.

> > You did not answer my question, which OS are you using ?
> Now I use Windows/Debian on my personal computer, both with Ada installed.
> Previously:
> 15-node cluster - AIX
> 128-node cluster - AFAIR TurboLinux (no Ada installed, I had to install gnat
>                                       in my home directory)
>                     Now they have Debian on it.

So I don't see a problem there. GNU/Linux Debian is well supported by GNAT.
GNAT is maybe already on your system as it is installed along with the other
GCC's compilers.

Pascal.

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