Path: utzoo!attcan!uunet!tut.cis.ohio-state.edu!ucsd!usc!zaphod.mps.ohio-state.edu!sol.ctr.columbia.edu!emory!hubcap!berryman-harry
From: berryman-harry@CS.YALE.EDU (Harry Berryman)
Newsgroups: comp.parallel
Subject: Re: Religious Wars(was SIMD vs MIMD programming)
Summary: Software Inadiquat on SIMD & MIMD
Message-ID: <9654@hubcap.clemson.edu>
Date: 12 Jul 90 17:04:26 GMT
Sender: fpst@hubcap.clemson.edu
Followup-To: comp.parallel
Lines: 38
Approved: parallel@hubcap.clemson.edu

>>_standard_ Fortran 90. MIMD systems can only be programmed in a
>>language that contains extensions for synchronization.  The SIMD
>>                       Ian Kaplan
>>		       MasPar Computer Corp.
>>		       ian@maspar.com
SIMD is a style of programming, as well as machine orginization.
You can write SIMD code for MIMD machines, just ask Q. Stoute.

>Myrias machines are programmed in standard Fortran 77. To make a
>program run in parallel, it is necessary to label the loops that can
>be executed in parallel, by putting 'PAR' in front of the 'DO'. If you
>don't do this, your program runs serially, but it still runs.
>Programs on a Myrias machine run deterministicly, and the machine
>All Myrias machines support full source-level symbolic debugging as a
>standard feature.
>
>
>Stuart Lomas				sjl@myrias.com or uunet!myrias!sjl
>Myrias Research Corporation		phone: +1 403 428 1616
>#900 10611 98 Ave, Edmonton, Alberta, Canada, T5K 2P7

Programs on the Myrias DO NOT run deterministicly. This by the admission
of several of your technical staff. The Myrias creates a page
for each iteration of a PARDO loop. To deal with reduction vars,
the pages are "merged", and the order of the merge is not deterministic.
Thus floating point operations may get done in different orders.
Also, since when is PARDO a standard Fortran 77 construct?
Get your story straight.

Religious wars may be entertaing, but seldom are useful. May I suggest
that those who have not programed in both SIMD and MIMD think before
they speak?

Scott Berryman 
Dogma Catcher
ICASE/NASA Langley Research Center
or 
Yale University CS Dept.