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From: cleary@calgary.UUCP (John Cleary)
Newsgroups: net.arch
Subject: Re: Memory Law
Message-ID: <560@calgary.UUCP>
Date: Fri, 15-Nov-85 22:20:55 EST
Article-I.D.: calgary.560
Posted: Fri Nov 15 22:20:55 1985
Date-Received: Wed, 20-Nov-85 20:22:58 EST
References: <764@bu-cs.UUCP>
Organization: University of Calgary, Calgary, Alberta
Lines: 28

> .... I noticed that raising our 750 to 8MB seemed not to help much.
> As a matter of fact, under some common conditions I suspect it might have
> made it worse...
> 
> Sooooo....I have been trying to come up with a reasonable rule of thumb
> for how much memory is too much (?!) It will go something like this:
> 
> 	Don't buy more memory than your CPU can zero out in N seconds.

> (I know, given enough memory you could use it as a RAMDISK, but let's
> .....

I suspect any system where you can speed it up by pretending that part of
RAM is a disk is badly designed/tuned.  It is true on the MacIntosh where it is
a symptom of the naive memory (mis)management on that machine.
Surely tuning an OS by increasing its page size in proportion to memory
size will help with things like memory management overheads.

The main reason for this type of problem seems to be the lingusitic and 
intellectual separation of disk files from other data structures, which is a 
hangover from the days when machines had 8KB of RAM and 10MB of disk.

John G. Cleary, Dept. Computer Science, The University of Calgary,
2500 University Dr., N.W. Calgary, Alberta, CANADA T2N 1N4. Ph. (403)220-6087
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