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From: throopw@xyzzy.UUCP
Newsgroups: comp.arch
Subject: Re: Single tasking the wave of the future?
Message-ID: <430@xyzzy.UUCP>
Date: Mon, 7-Dec-87 12:40:16 EST
Article-I.D.: xyzzy.430
Posted: Mon Dec  7 12:40:16 1987
Date-Received: Sat, 12-Dec-87 10:38:28 EST
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> peter@sugar.UUCP (Peter da Silva)
> Until you have something incredible like 64000 processors in your
> box, you're going to find yourself running out of the suckers. 

Note that argument that "we don't need to multiplex a single processor
because we can simply throw more processors at the problem" is the same
argument as "we don't need to have demand paging because we can simply
buy more and more memory".  I think that both are incorrect arguments,
for exactly the reasons that Peter points out:

> What happens when you want to start up that 5th or 9th program and you've
> only got 4 or 8 CPUs?

Or, what happens when you want to keep N processes handy at a convenient
point in mid-execution, when they total to M pages of address space and
you've only got (M-1) pages of physical memory?

I think virtual processors are just as important as virtual memory.  And
I think virtual memory is *very* important.  The fact that many PCs
throw these things away is, I think, a Bad Thing.

--
"Solve THIS!"
"'Mighty Mouse is a wimp.'  But what does it mean?"
"It means you've made me MAD!"
                        --- Mighty Mouse to alien brain.
-- 
Wayne Throop      !mcnc!rti!xyzzy!throopw