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From: jet@karazm.math.uh.edu ("J. Eric Townsend")
Newsgroups: comp.unix.aix
Subject: Re: Paging space problems
Message-ID: <1991Feb9.211429.16971@lavaca.uh.edu>
Date: 9 Feb 91 21:14:29 GMT
References: <36829@netnews.upenn.edu> <5170@awdprime.UUCP> <19044@rpp386.cactus.org>
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In article <19044@rpp386.cactus.org> jfh@rpp386.cactus.org (John F Haugh II) writes:
>Or you could avoid unnecessarily killing the X server, which causes the
>loss of quite a few pages at a whack.  That was the biggest page sucker
>that I was ever aware of.

I have a question about paging/swapping, and I hope that someone here is
legally able to answer it.

This is from an RS/6000, model 320, 8Mb RAM, 30+MB paging, AIX 3002,
just rebooted.

$ ps aux
    USER   PID %CPU %MEM    SZ   RSS     TT STAT  TIME CMD
    root     0 0.0%  78%  7536  6360      -    S  0:01 swapper
    <rest of listing deleted for brevity>


The manual page for ps says that SZ is...  Interesting, I just did
"man ps" and got back a prompt.  "man -k ps" shows that there is
indeed a man page for ps.  Oh well.  You probably know what SZ and RSS
mean anyway...

The point is, why is the swapper taking up 78% of memory?!?

I called IBM Defective Support and asked if it should be that large,
and the convo was (paraphrased):
me: "Is it supposed to be that big?  If so, what does it mean?  Other unixes
     don't behave this way."
support: "yes, it's supposed to be that big."
me: "Well, is that the size of the page table perhaps, and ps(1) is confused,
and believes that swapper is that big, when in fact, swapper just happens
to own *all* the pages for the system?"
support: "No, the swapper is just big.  AIX does things differently than
other unixes"

We're going to go to 32Mb soon (finally).  Will 6-7Mb of our memory be
wasted by the swapper then as well?  We have a typical job size of 25-30Mb,
so we feel we should only have to go to 32Mb -- the OS shouldn't eat
up more than 2Mb of space if there's only one user process running.

This is something we are *very* concerned about, as we're considering
buying several 8Mb machines and using them as computation engines for
small jobs (ie: installing only the os and compiler packages, no windowing
software, get there via telnet or dumb terminal).  If we have to buy an
extra 8Mb of ram just for the OS, then the cost becomes unreasonable.

Answers?  Hints?  Anonymous phone calls with an adb-able patch? :-)

--
J. Eric Townsend - jet@uh.edu - bitnet: jet@UHOU - vox: (713) 749-2120
"It is the cunning of form to veil itself continually in the evidence
of content.  It is the cunning of the code to veil itself and to produce
itself in the obviousness of value." -- Baudrillard