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From: jayasim@cis.ohio-state.edu (D Jayasimha)
Newsgroups: comp.parallel
Subject: Re: fine->medium->coarse
Message-ID: <9253@hubcap.clemson.edu>
Date: 8 Jun 90 12:25:30 GMT
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Approved: parallel@hubcap.clemson.edu


In article <9166@hubcap.clemson.edu> george%avocet@cs.utah.edu (Lal George) writes:
>I would like clarification regarding the proper meaning of 
>the terms fined grained, medium grained and coarse grained 
>parallelism. I have seen the latter two being used 
>interchangeably. Where does one typically draw the line between
>medium and coarse grained parallelism. 
>
>Thanks.
>
>Lal.

As others have pointed out, there is no standard defintion to say what
a "grain" is.  But, I find the following to be a useful guide- a "grain"
is the smallest scheduling unit on a processor- the "definition" is
biased towards scheduling of processes and one could poke holes at the
definition (for example, there is also an implicit language model assumed)
- nevertheless, I find it to be useful:

Fine grained parallelism- exploits parallelism at the "basic operation
level" (e.g., addition, multiplication)

Medium grained parallelism- exploits parallelism at the loop level, i.e.,
an iteration of a loop level is the scheduling unit;

Coarse grained paralleism- exploits parallelism at the subprogram level,
i.e., a subprogram or a procedure is the scheduling unit.

d n jayasimha (jayasim@cis.ohio-state.edu)
Dept of Comp & Inf Sc
The Ohio State Univ
Columbus, OH 43210.