(j3.2006) (SC22WG5.3745) Nick's MPI non-blocking proposal

[Van Snyder]

On Thu, 2008-12-04 at 15:14 -0800, Aleksandar Donev wrote:
> Bill Long wrote:
> 
> > Actually, I find it massively confusing.
> No surprise, since you are confused about what Nick means by I/O.
> Nick's proposal is meant to cover send/receive as well. It is I/O in
> common computer science lingo, .... Just replace I/O with "data
> transfer" and you should be less confused reading his draft.

I haven't used MPI for 12 years, so there is much about it I don't
remember, and I'm sure there are developments since I stopped using it.
But...  My recollection was that it was an enormous kludge that does
almost nothing other than I/O.  My present codes use PVM, but only for
inter-program data transfer.

Yeah, there's some synchronization stuff, too, but if you know you have
to accomplish this using interprocess or interprogram communication, as
opposed to inter-image shared-memory communication, you might as well do
that with I/O, too.

Therefore, Nick's proposal inevitably adds yet another kludge to the
dung heap.

Several times, it has been proposed to add one more spec to the OPEN
statement to give extra processor-dependent information to the
processor, with notes pleading to use the information to set up an
interprocess communication channel, perhaps using MPI, PVM or some
proprietary method.  I proposed this in 1986, 97-114:17.3 and 08-204,
and others have proposed it, too.  08-204 proposed adding one row to a
syntax rule, a dinky one-paragraph subclause in Clause 9, one item in
Annex A, and one small paragraph in Annex C -- altogether 19 lines of
plain text, and inevitably much less in typeset LaTeX.  Compare this to
the 406 pages of MPI-3.

If that were in place, perhaps with the addition of arrays of unit
numbers in WRITE statements for broadcasts, and if asynchronous I/O and
DIO worked with it (and why wouldn't they?), why would anybody use MPI
or PVM for anything other than legacy codes?  If it had been done in
Fortran 90, would anybody ever have used MPI or PVM in Fortran?

-- 
Van Snyder                    |  What fraction of Americans believe 
Van.Snyder at jpl.nasa.gov       |  Wrestling is real and NASA is fake?
Any alleged opinions are my own and have not been approved or
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