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From: rod@CHEETA.ISI.EDU.UUCP
Newsgroups: mod.computers.vax
Subject: Tuning
Message-ID: <870324172509.000@Cheeta.ISI.Edu>
Date: Tue, 24-Mar-87 20:25:10 EST
Article-I.D.: Cheeta.870324172509.000
Posted: Tue Mar 24 20:25:10 1987
Date-Received: Thu, 26-Mar-87 06:29:48 EST
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Hey Jerry, (or anyone else who can answer questions quickly, coherently,
and correctly),

	With all this talk about tuning in general, I have a specific
question. We have several 750's in a cluster with one 8650. Most of the
750's are nominally single-user machines.

	The setup:

	8 Meg of memory
	WSMAX	 12288
	WSEXTENT 12288
	WSQUO	1024
	WSDEF	150
	BORROWLIM	236
	FREEGOAL	189
	GROWLIM		188
	FREELIM		63

The primary use of these machines is a large program which likes to have
a working set of at least 10240 pages (its response is horrendous and it
pages something awful without that), but will gladly take whatever it
can get.

    With all the other activity on the machine (mail, small user processes,
Decnet, etc.) there are usually around 10-11K pages to be had, sometimes
a little more.

    The problem: The user is running along just fine, with a working set
of around 10K pages, when all of a sudden he gets knocked on his butt,
all the way back to 1024 pages. It then takes him a while to get back
up to speed again.

    What could be causing this? How can we remedy it?

    PFRATL is currently set to 0, but raising it to something low
didn't seem to correct the behavior. I think it's still probably not
a good idea to have it at zero. Comments? PFRATH is 120. The idea is to
try to keep the user in memory even if he's not pagefaulting much. Is
there a better way?

    WSINC is 150, WSDEC is 35.

    Is there anything wrong with raising WSEXTENT all the way through the
ceiling? It couldn't hurt to allow users to get more memory on the 8650
than the 750s, I don't suppose, provided no one else wants it. I would
assume the proper way to handle this is to make WSEXTENT enormous, and then
set WSMAX to something appropriate on each machine, like around the size
of physical memory minus some overhead. Am I missing anything?


	    Thanks,

	    --Rod