Newsgroups: comp.sys.amiga.hardware
Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!think.com!mintaka!geech.gnu.ai.mit.edu!rjc
From: rjc@geech.gnu.ai.mit.edu (Ray Cromwell)
Subject: Re: A3000 CPU Wars!!
Message-ID: <1991Jun5.072620.18879@mintaka.lcs.mit.edu>
Sender: news@mintaka.lcs.mit.edu
Organization: The Internet
References: <16888@helios.TAMU.EDU> <1991Jun5.060518.9683@news.iastate.edu>
Date: Wed, 5 Jun 91 07:26:20 GMT
Lines: 57

In article <1991Jun5.060518.9683@news.iastate.edu> taab5@isuvax.iastate.edu writes:
>   The reason is that neither AmigaDOS nor UNIX (the two operating
>systems you can run on an A3000) support multiprocessing.  For this

  Not quite. AT&T(or was it Sequent?) is working on a version of 
SysV which will support multiple processors. There are also some
microkernels floating around that support multiprocessing. Multiprocessing
isn't prohibited by AmigaDOS. For instance, it would be easy to add in
a 34010, 68030, or i860 and have certain graphic or i/o operations offloaded
to it. (Easy in the sense, that once you get the board working
with it's own ram, and graphic kernel you could patch gfxlib to
call the functions on the 34010. You could also add in some
super-duper floating point co-processor chip and write a new
mathtrans/doubbas.library to handle it.) 
  Multiprocessing in the area of 'several processors sharing the same
bus, memory, and code space, and executing different program threds to
accomplish the final goal (output the solution)' is a different problem.
It has less to do with the OS and more to do with _how_ you code it.
It's an ongoing problem in CS. Some operations are sped up by using
many processors (vector and matrix operations) other operations get
no bonus for multiple processors. The language extension Linda was
created to help the problem. I don't know how far it has gone, but
I don't think it has reached a point yet where you can keep adding
processors into a system and get a linear speed up in the execution.
Sometimes the algorithm may have to be rewritten to work in parallel.
Most Connection Machines I've seen have Sun/HP front ends that offload
stuff like Mathematica onto the CM? 

>      I hope this answers your question.

  I think the original poster was slightly confused and thought that
adding processors together is like adding numbers. It isn't that
easy. (reminds me of relativety and how people thought velocity
vectors were added like any other quantity)

  I'm waiting for the day when they can build a 1 teraflop computer and
actually have benchmarks run at that speed (without recoding the
benchmark to run in parallel)

  Hmm, anyone wanna tell me how transputers work? (multiprocessing)?

>>
>>Andy.
>  -------------------------------------------------------------
> / Marc Barrett  -MB- | BITNET:   XGR39@ISUVAX.BITNET        /   
>/  ISU COM S Student  | Internet: XGR39@CCVAX.IASTATE.EDU   /      
>------------------------------------------------------------    
>\  ISU : The Home of the Goon                             /
> \       Who wants to Blow Up the Moon                   /
>  -------------------------------------------------------


--
/ INET:rjc@gnu.ai.mit.edu     *   // The opinions expressed here do not      \
| INET:r_cromwe@upr2.clu.net  | \X/  in any way reflect the views of my self.|
\ UUCP:uunet!tnc!m0023        *                                              /