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From: zemon@felix.UUCP (Art Zemon)
Newsgroups: comp.unix.wizards
Subject: Re: Lack of core & swap space causing problems
Message-ID: <8017@felix.UUCP>
Date: Mon, 28-Sep-87 16:35:44 EDT
Article-I.D.: felix.8017
Posted: Mon Sep 28 16:35:44 1987
Date-Received: Thu, 1-Oct-87 03:20:09 EDT
References: <12981@comp.vuw.ac.nz>
Sender: daemon@felix.UUCP
Reply-To: zemon@felix.UUCP (Art Zemon)
Organization: FileNet Corp., Costa Mesa, CA
Lines: 43


Under most Unix variants, including Ultrix through the
current 2.0 release, all processes are allocated swap space
even though they may never actually swap.  That means that
the total size of all the processes which are running on
your system is limited to the SMALLER of your physical
memory and your swap space.

To bring this closer to home, we have an 8700 with 32 Mb of
physical memory and 64 Mb of swap space.  Even though we
almost never page and *NEVER* swap, I need this much swap
space.  It is now 1:30pm and the load average is only 2 but
I have 38 Mb of swap space allocated (pstat -s give you this
figure).

Finally, if you are running out of swap space or memory, I
suggest you look for programs which gobble large amounts of
memory.  Use either "sps -la" or "ps -lagx" and look for big
numbers.  I had been running out of my 64 Mb of swap space
and found the culprit was sysline!  The dang program reads
the entire process table into its own address space just so
it can tell you how many processes you have running!!  On
small machines this is not an unreasonable thing to do but
on our 8700, every one of about 50 invocations of sysline
was trying to use 750 Kb.  I pulled out the offending code
and sysline is now down to a more reasonable 132 Kb.

I have heard about some new VM implementations that don't
allocate swap space until it is really needed.  It's about
time!  There was also a talk at the Phoenix Usenix (by
Gould, I think) about a VM system that let you allocate VM
up to the sum of swap space plus physical memory.


In summary, to get rid of your "killed on swap error" and
your "not enough core" error messages, either add physical
memory, add swap space, or reduce the size/quantity of the
programs you are running.
--
	-- Art Zemon
	   FileNet Corporation
	   Costa Mesa, California
	   ...!hplabs!felix!zemon