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From: McGuire_Ed@GRINNELL.MAILNET
Newsgroups: mod.computers.vax
Subject: VMS: process page file usage
Message-ID: <8607080831.AA10551@ucbvax.Berkeley.EDU>
Date: Mon, 7-Jul-86 17:29:00 EDT
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Posted: Mon Jul  7 17:29:00 1986
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***** Is there a wizard in the house? *****

I have written a DCL procedure which predicts the process capacity of
page/swap files by projecting from their current usage and the number of
processes on the system.  (I assume that the page file space should be
kept 1/2 free and swap file space 1/4 free.) I subtract the usage of
system processes from page/swap file capacity, for a more accurate
prediction, projected solely from the real workload of the systems.

And now my question:  Is it possible to determine the page file usage
for a process, short of scanning the page tables for swapped pages?

Right now, I make the excessively liberal estimate that system processes
don't map any page-file pages.  Of course, I could also err on the side
of conservatism (and I don't want to do THAT :-)), and estimate that
they are using working-set-size minus process-page-count pages, but that
makes even more inappropriate assumptions.

I am computing swap file usage for the processes by raising working-
set-size to the next multiple of MPW_WRTCLUSTER.

Any suggestions for page/swapfile management would be MOST appreciated:
we're now running a 4-node VAXcluster with an aggregate of 80MB--these
babies are getting LARGE!  Not to mention the dump files...

[My procedure reports the number of processes on the system broken down
by MODE; MAXPROCESSCNT and Login Interactive Limit; free and total
page/swapfile pages; projected capacity.  If anyone wants a copy, send
me a note.  I'll distribute it individually, or post it if I get more
than 10 requests.]