Sun4 and thrashing problems

[Kevin M. Deford]

We have a Sun 4/280 with 128 MB of memory running OS 4.0.3.  We have
noticed the following odd behavior.  One of our users has a program who's
compiled size is ~150 MB.  This is due to 2 very large arrays whos
behavior is not sequential (some sort of gaussian reduction).  When this
program runs, the system begins to exhibit a tendency to be spending alot
of time paging this program in and back out again (there are other
programs running).  While the program is being paged out, the system
blocks all processes and since the program is 150 Mb large, this takes on
the order of minutes.  This cycle will continue every 3-5 minutes.

The other odd thing is that even though there is 128Mb of memory, the
system only allows utilization of around 90Mb (machine configured 128 on
boot up).  

Has anyone had any experience with either of these problems?

Kevin M. DeFord
Internet: deford at linus.mitre.org; UUCP: {decvax,philabs}!linus!deford
Office: 1A420, phone (617)271-3424
Mitre Corporation, Bedford, MA 01730