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From: mat@amdahl.UUCP (Mike Taylor)
Newsgroups: net.arch
Subject: Re: VERY LARGE main memories
Message-ID: <3595@amdahl.UUCP>
Date: Fri, 29-Aug-86 11:59:54 EDT
Article-I.D.: amdahl.3595
Posted: Fri Aug 29 11:59:54 1986
Date-Received: Fri, 29-Aug-86 21:36:10 EDT
References: <1130@bu-cs.bu-cs.BU.EDU>
Organization: Amdahl Corp, Sunnyvale CA
Lines: 29

In article <1130@bu-cs.bu-cs.BU.EDU>, bzs@bu-cs.BU.EDU (Barry Shein) writes:
> The point is it is not clear that increasing memories unbounded
> produces unbounded performance gains, in fact, it almost certainly
> doesn't.

As a matter of interest, studies we did some time ago with IBM MVS
indicated that performance reaches a maximum and then begins to
deteriorate slowly. Not a general result, of course, but food for
thought.  BTW, we offer up to 512MB of mainstore on our systems.

> 
> You need a CPU (or more than one) to do something with all this
> wonderful stuff you have in memory.
> 
> Of course, assuming the memory were free and reasonably random behavior
> I agree that a huge memory would have some value to a database application
> that filled the memory, but I doubt it would be a reasonable thing to
> do unless memory prices dropped drastically. You'd probably be better
> off putting your money into the processor (the context of the argument
> seemed to imply smaller processors, obviously Cray is already up against
> that limit.)
> 

But what do you do when you can't put any more money into the processor?
Not only Cray is up against that limit.
-- 
Mike Taylor                        ...!{ihnp4,hplabs,amd,sun}!amdahl!mat

[ This may not reflect my opinion, let alone anyone else's.  ]