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From: franka@mntgfx.MENTOR.COM (Frank A. Adrian)
Newsgroups: comp.arch
Subject: Re: Processing
Message-ID: <619@franka.mntgfx.MENTOR.COM>
Date: Tue, 28-Apr-87 00:13:35 EDT
Article-I.D.: franka.619
Posted: Tue Apr 28 00:13:35 1987
Date-Received: Wed, 29-Apr-87 07:12:40 EDT
References: <505@sw1e.UUCP> <110@hippo.UUCP> <6123@bu-cs.BU.EDU> <6654@bu-cs.BU.EDU> <113@umich.UUCP> <6872@bu-cs.BU.EDU>
Reply-To: franka@mntgfx.UUCP (Frank A. Adrian)
Organization: Mentor Graphics, Beaverton, OR
Lines: 43

In article <6872@bu-cs.BU.EDU> bzs@bu-cs.BU.EDU (Barry Shein) writes:
>My favorite example is we saw automobiles in the beginning of the
>century go from (max) 10MPH to 30MPH to 100MPH. But after that first
>(ca.) 30 years of development extrapolating the curve became
>ridiculous. The cost of building a car and designing a road system
>which would transport the average person at 300MPH became ridiculously
>out of reach. Sure, there's a flaw here in that lots of MIPs won't
>endanger your life (maybe, I could argue that one also, but it's more
>socio-technical) but the point where you cross over beyond
>cost/benefit might exist in a similar fashion. And maybe some day
>we will build 300MPH passenger cars, *maybe*.
>
>	-Barry Shein, Boston University

I agree completely with the above argument.  Lets talk about constraints as
it applies to I/O bandwidth.  Let's postulate a machine with 4 Tbytes of
memory and a GAF (Gawd Awful Fast) CPU with unlimited bandwidth.  Lets look
at the new bottleneck in the system.  Here I am with a (small :-) 2Tb object
(say something dumb like an atmospheric model (which someone said he wanted
to do at home with data fed in from a worldwide sampling network)), and I
want to send it to a friend.  Lets look at some shirtsleeve calculations.
Let's see how long I have to wait to send this data at different baud rates:

baud    time
----    ----
9600    17Gs     (this is GIGA, folks)
50K     320Ms    (getting better, but still have to wait a while)
50M     320Ks    (down to about 9 hours)
50G     320s.    (right ballpark)

OK, now we're talking about the full effective bandwidth of a good size
communications satellite (using several parallel channels), and it still
takes ~5 minutes to dump half your physical memory.  Now I don't think that
we have enough bandwidth to support all of the I/O bandwidth we are going to
need, and that's the communication infrastructure which needs to be in
place before we even get enough data to need these sizes of memories and CPU
speeds.  Also, if 4 Tbytes is a physical memory, what's a storage device
going to look like?  Electron beams fired just outside the event horizon of
quantum black holes to form storage loops?  Gives a whole new meaning to the
phrase "spin-up".  Just food for thought...

Frank Adrian
Mentor Graphics, Inc.