CHIN%PLU@IO.ARC.NASA.GOV (04/30/88)
National Aeronautics and Space Administration
Ames Research Center
SEMINAR ANNOUNCEMENT
SPEAKER: Seth Steinberg
TOPIC: Butterfly Lisp
The BBN Butterfly is a shared memory multiprocessor which can be
configured with up to 256 processors. Over the last several years we
have developed a Lisp system which takes advantage of this hardware,
by providing for the parallel execution of lightweight tasks in a
shared Lisp world. Tasks are created using the future mechanism which
automatically provides for data directed task synchronization. Other
tasking and synchronizing techniques may be used as well.
In an attempt to understand how parallel programs execute, we installed
a tracing system to record the fine details of tasking and
synchronization. This data is then used to produce a picture showing
both the task creation tree and the task synchronization tree. These
pictures have shed light on the behavior of a number of parallel
programs.
Butterfly Lisp can be described as locally serial, since, whenever
possible, sections of code which contain no parallel constructs will
execute as they would on a serial processor. Preserving this
property while combining such features as tasking, unwind protection
and special variables has required us to make a number of changes in
the way these features are implemented.
The system is now being ported to run on the BBN GP-1000 processor
under the Mach operating system and a new compiler is being tested
which takes advantage of Common Lisp type declarations.
BIOGRAPHY:
Seth Steinberg has been working with computers since the late '60's
and has an M.S. in Computer Science from MIT. He spent seven years
working for Nicholas Negroponte doing systems programming, language
development and graphics at the Architecture Machine Group. (Now the
nucleus of the Arts and Media Technology Center) In 1979, he joined
Software Arts where he designed and developed TK!Solver, a constraint
relaxation system for personal computers. More recently he has been
working on a parallel Lisp implementation for the BBN Butterfly
multiprocessor.
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DATE: Monday, TIME: 2:00 - 3:00 pm BLDG. 244 Room 103
May 2, 1988 --------------
POINT OF CONTACT: Marlene Chin PHONE NUMBER: (415) 694-6525
NET ADDRESS: chin%plu@ames-io.arpa
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