SparcStation I Memory Leak?

[Chet Murthy]

I have been running a large LISP application on a SparcStation I for a
while now, and I have noticed some really awful problems with the
allocation of memory as time goes on.

Here's the scenario:

I have a Sparcstation I with 16MB of memory, 2 100MB internal prodrives,
and an external 700MB SCSI drive (HP).  I use 120MB of the internal drives
for swapping and all the HP drive also.

So I start up a Lucid LISP process which takes up 256MB of swap.
Initially, I usually get around 8MB of memory (as shown by ps), but that
drops off to around 3.9MB pretty soon.  If somebody else starts up a
semi-large program, my RSS allocation drops further, and even if they
finish their application, I don't get any more memory.

After about a day or 2, my LISP is getting less than 2MB of RSS, on a 16MB
machine!

Now, I thought that perhaps this was because of the particular kind of
LISP job I was running.  But when I run the same exact job on a SUN-4/260
Sparc with 32MB of memory, even in the presence of other large,
compute-intensive jobs my working set never drops below 10MB, and often
hovers near 21MB.

Moreover, I can see the noticeable slowdown from day 1 to day 2 to day 3,
as my program is getting less and less memory.

This makes the Sparc almost useless by the end of the third day - just to
check, I killed my LISP job and restarted it after the Sparc had been
running 3 days, and it got around 3-4MB of memory - down from 8MB
initially.

A friend noticed that if you write a C program that malloc's 64MB, and
then repeatedly copy a random amount of bytes between 1 and 256 between
two random pointers into that data space just allocated, say, 100,000
times, pretty soon your C program will end up with a working set of around
a quarter of a Meg on a 16MB workstation.

Does anybody know WHY the Sparc is so brain-damaged?  I don't see how this
could be anything other than a memory leak.

As I mentioned before, if I kill the LISP and restart it, I don't get
nearly as much RSS as I had the first time around.  So it doesn't seem
possible that it could be anything other than a leak in the kernel.

What's going wrong?  Why is my Sparc useless after 3 days?

	murthy at cs.cornell.edu