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From: aarons@cvaxa.UUCP (Aaron Sloman)
Newsgroups: net.arch,net.ai
Subject: M68020 and SUN3
Message-ID: <166@cvaxa.UUCP>
Date: Sat, 9-Nov-85 15:28:48 EST
Article-I.D.: cvaxa.166
Posted: Sat Nov  9 15:28:48 1985
Date-Received: Tue, 12-Nov-85 03:59:33 EST
Organization: Univ of Sussex, Cognitive Studies, UK
Lines: 44
Xref: watmath net.arch:2074 net.ai:3093
Xpath: warwick ubu

I've seen much discussion of  relative merits of processors in
netmail, but very little on M68020. This surprises me, in view
of our recent experience. SUN Microsystems lent us a SUN-3 for
a few days to see if we  could port Poplog to it. Some changes
from  the  SUN-2  version  were   needed,  but  then  it  ran,
essentially using only the  M68010 compatible instructions. In
spite of that  we found a three fold speedup,  and although we
did not  have time  for exhaustive testing,  pretty conclusive
evidence that  it outperformed  a VAX-780, for  instance. Here
are our Prolog 'naive reverse' test results, to illustrate:

    SUN-3   (UNIX 4.2)  9500 LIPS
    GEC-63  (UNIX V)    6140 LIPS
    VAX 780 (VMS)       5360 LIPS
    SUN-2   (UNIX 4.2)  3210 LIPS
    VAX 750 (UNIX 4.2)  3000 LIPS (with Systime accelerator)

Each  is the  best  time  of several  runs  on  a single  user
machine,  without  garbage  collection,   so  is  only  partly
representative of actual performance.

This 'quick' port was done by Jonathan Laventhol who estimates
that if we did it properly, using the new M68020 instructions,
there would be a substantial reduction in the size of compiled
programs, and a further speed-up, possibly up to a factor of 5
times SUN-2 instead of only 3  times. This is because a lot of
groups of  three instructions would  be replaced by  two. Even
without  this,   however,  we  were  very   impressed  by  the
performance.  Of   course,  we  can  say   nothing  yet  about
reliabilit, etc. The  machine we were lent was  a 4Mbyte SUN-3
with 71 Mbyte  disk, two RS232 ports and a  tape cartridge. It
looks as if  we can begin to expect  performance comparable to
(e.g. Symbolics) on a cheaper machine.

I am  very impressed, and  it looks  as if Motorola  (and SUN)
have produced a  real winner. I presume  Quintus Prolog, Lucid
Common Lisp, etc. etc. will all experience the same speed-up.

Aaron Sloman, Cognitive Studies Programme,
University of Sussex, Brighton, England.
-- 
Aaron Sloman, U of Sussex, Cognitive Studies, Brighton, BN1 9QN, England
uucp:...mcvax!ukc!cvaxa!aarons  arpa/janet: aarons%svga@uk.ac.ucl.cs
                                     OR     aarons%svga@ucl-cs