Path: utzoo!utgpu!jarvis.csri.toronto.edu!rutgers!apple!motcsd!xdos!doug
From: doug@xdos.UUCP (Doug Merritt)
Newsgroups: comp.sys.amiga.tech
Subject: Re: address spaces
Message-ID: <380@xdos.UUCP>
Date: 13 Jun 89 15:08:15 GMT
References: <8906122014.AA25923@postgres.Berkeley.EDU>
Reply-To: doug@xdos.UUCP (Doug Merritt)
Organization: Hunter Systems, Mountain View CA (Silicon Valley)
Lines: 40

In article <8906122014.AA25923@postgres.Berkeley.EDU> dillon@POSTGRES.BERKELEY.EDU (Matt Dillon) writes:
>jms@tardis.Tymnet.COM (Joe Smith) Writes:
>:Parts of this prediction are already here.  BiiN (formed by Intel + Siemens)
>:has a system with 2**26 address spaces.  Any of which can be shared or
>
>	This sounds like Multics... nothing new at all.  It turned out that
>(w/ Multics) the overhead made for very slow memory access as well as a huge
>overhead for inter process / shared library calls.

Well sure, "there's nothing new under the sun". But the fact that Multics
did something badly doesn't mean much...it had high overhead for many things.
Unix itself was a reaction to Multics, and it implemented some inefficient
Multics features in an efficient way.

Consider, by analogy, garbage collection. It has been implemented inefficiently
many times. Does that mean it will always be high overhead, and therefore
always left out of e.g. systems programming languages? Not at all...
although I'm not up on the best algorithms, a researcher at XEROX PARC
told me recently that the GC algorithm they're using in their YGGDRASIL
hypertext system consumed only 5% of the runtime.

Or consider the Intel 432, which supports objects in a slow kind of way.
Then compare that with the implementation of the Smalltalk 80 kernel.

It's often true that powerful ideas languish until implementation
technology progresses to the point where "very slow" becomes "acceptably
fast". Sometimes this happens through hardware advances (e.g. remotely
mounted file systems became widely acceptable when reasonably fast LAN
technology became cheap), other times through software advances (development
of more efficient algorithms).

My posting that Joe responded to didn't say anything at all about "new"
technologies; it was talking about those things becoming common rather
than curiosities. Surely you don't think that the general kind of system
architecture that is so popular today will still be widely used, say, fifty
years from now???
	Doug
-- 
Doug Merritt		{pyramid,apple}!xdos!doug
Member, Crusaders for a Better Tomorrow		Professional Wildeyed Visionary