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DEPARTMENT OF COMPUTER SCIENCE
UNIVERSITY OF WATERLOO
SEMINAR ACTIVITIES

PROGRAMMING LANGUAGES SEMINAR

                    -Monday, May 8, 1989

Mr.  Richard  Stroobosscher,  a graduate student of the
Dept. of Computer Science, University of Waterloo, will
do  a  Master's  Essay  Presentation  on ``Light Weight
Processes   in   a  Shared  Memory  Multiple  Processor
Environment.''

TIME:                 1:30 p.m.

ROOM:              DC 1304

ABSTRACT

Light-weight  processes  are a mechanism for expressing
medium-grain    concurrency.     When   the   cost   of
manipulating light-weight processes approaches the cost
of   manipulating  procedures,  they  become  a  viable
alternative to procedures.  Light-weight processes have
the  added  benefit  of being able to take advantage of
any  parallelism  in  the  hardware  on  which they are
implemented.

This  talk  discusses  an  engineering  exercise in the
implementation  of  light-weight  processes  for  the C
programming  language.   The light-weight processes are
provided  through  a  library  of  functions called the
uSystem.

The  uSystem  is designed to be portable across various
flavours  of  the  UNIX  operating  system.   On single
processor  machines,  the  uSystem  time-slices  light-
weight  processes,  but on multiple processor machines,
the   uSystem   executes   light-weight   processes  in
parallel.

The  single processor uSystem is implemented on various
VAXen,  Sun  68020s,  a  Symmetry  80386  and  two MIPS
processors.   The uSystem is capable of passing 16 byte
messages  between processes at 120 microseconds on some
of  these  machines.  The multiple processor uSystem is
implemented  on  a  Symmetry  with  6 80386 processors.
Program execution has shown linear improvement with the
addition of more processors.