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From: forbus@uiucdcsp.CS.UIUC.EDU
Newsgroups: net.ai
Subject: Re: Any data on programmer productivity
Message-ID: <3500008@uiucdcsp>
Date: Sun, 3-Nov-85 14:33:00 EST
Article-I.D.: uiucdcsp.3500008
Posted: Sun Nov  3 14:33:00 1985
Date-Received: Tue, 5-Nov-85 23:01:46 EST
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Nf-From: uiucdcsp.CS.UIUC.EDU!forbus    Nov  3 13:33:00 1985


Ahem.  How many people who buy vax 780's give them to a single user?  Worse
still, many people who buy Suns seem to run them with multiple users, and
often swapping over a network to a shared disk.  The latter is a crazy idea
for AI programs; while the ethernet may or may not be a bottleneck, sharing
a disk between several processors certainly is!  And of course, none of the
Gabriel benchmarks really test paging performance, which is where
non-trivial AI programs spend most of their time.

Some of my students have tried to bring up programs written for Symbolics
machines on Suns, and vice-versa.  Factors of 15 performance improvement are
not uncommon.  The Suns involved were NOT Sun-3's, and the dialect was
Franz, so these figures shouldn't surprise anyone.  I'm quite curious to see
what will happen with Lucid's CommonLisp on Sun-3's when we can try
serious-sized programs.  Which, thankfully, with CommonLisp we can do with a
minimum of pain.

Remember, however, the original question refered to lisp machines
versus standard time-sharing environments.  If a stand-alone 20 with PSL
performs in the neigborhood of a Symbolics, then how will it do with
20-60 users?  Answer: very badly!  I think it is safe to say that there
is NO computer on the market which runs Common Lisp (other lisps are simply
not contenders at this stage of the game) which will provide for several
users at once the same performance they can get if they are sitting at
stand-alone workstations (be they Symbolics, Sun, TI, or Xerox).