Path: utzoo!utgpu!jarvis.csri.toronto.edu!cs.utexas.edu!tut.cis.ohio-state.edu!ucbvax!ziploc!eps
From: eps@toaster.SFSU.EDU (Eric P. Scott)
Newsgroups: comp.sys.next
Subject: Re: How do I shrink the swapfile (easily...)
Message-ID: <340@toaster.SFSU.EDU>
Date: 1 Mar 90 12:16:17 GMT
References: <2558@cs-spool.calgary.UUCP>
Reply-To: eps@sutro.SFSU.EDU (Eric P. Scott)
Organization: San Francisco State University
Lines: 34

I don't have an answer for you, but I did get to see what happens
when you run out of disk space.  This was on a machine that only
had a single 660MB drive at the time.  The swap file grew to 71
megabytes.  It was really weird doing a df and seeing the
filesystem 105% full.  Needless to say, the machine was pretty
much unusable.  There were a whole bunch of

	mach: IO error on pageout: error = 28.
	mach: vnode_pageout: failed!

messages.  (I love it: hey! we're out of disk space!  what should
we do?  let's note it in a log file!)

The swapfile did shrink a little when the cause went away, but
not by a useful amount.  Rebooting left about 35 MB free
according to df.


The culprit: one user, telnetting in, running one program:
Mathematica.  There aren't many things with such an insatiable
appetite for virtual memory--this guy wanted 51 megabytes.  I
wish I had, say, 48MB RAM in 4MB SIMMs for the memory pigs.
(This really makes me wonder about the wisdom of putting only 40MB
for swap+/tmp in each of the formerly diskless workstations...
Doesn't seem like enough for people who want to do real work.)

Interestingly enough, in its present configuration, the machine
rarely seems to get "slow" even with its mere 68030--it runs out
of process slots before horsepower.  Not that I wouldn't mind
seeing a faster processor (especially when printing).  Still,
nothing helps like having enough RAM.  You can tell when the
machine is paging because the performance loss is so noticeable.

					-=EPS=-