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From: mcdonald@uxe.cso.uiuc.edu
Newsgroups: comp.arch
Subject: Re: Memory utilization & inter-process
Message-ID: <46500075@uxe.cso.uiuc.edu>
Date: 26 Aug 89 14:47:00 GMT
References: <27927@<619868166>
Lines: 15
Nf-ID: #R:<619868166:27927:uxe.cso.uiuc.edu:46500075:000:773
Nf-From: uxe.cso.uiuc.edu!mcdonald    Aug 26 09:47:00 1989


One solution to the thrashing problem (in the particular case in point,
one or a few processes which are much too big for memory) is to break
down and recode the program so that it does explicit IO to get the
necessary pages. This can be particularly helpful if just ONE process
is too big for memory. There are people in our department who
diagonalize 1,000,000x1,000,000 sparse matrices (with maybe 50,000,000
non-zero elements) on machines with 16 megabytes of memory, and
nary a page fault ever occurs. Sometimes they can get full CPU utrilization
with just one process. What this DOES require, of course, is the
ability to do disk reads and writes concurrently with program 
execution. Some operating systems don't allow this, at least not
efficiently.

Doug McDonald