Path: utzoo!utgpu!water!watmath!clyde!att!osu-cis!tut.cis.ohio-state.edu!husc6!uwvax!vanvleck!uwmcsd1!ig!agate!ucbvax!KL.SRI.COM!STEINBERGER
From: STEINBERGER@KL.SRI.COM (Richard Steinberger)
Newsgroups: comp.os.vms
Subject: MPW_HILIMIT
Message-ID: <12408039534.10.STEINBERGER@KL.SRI.COM>
Date: 20 Jun 88 21:56:51 GMT
Sender: daemon@ucbvax.BERKELEY.EDU
Organization: The Internet
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I have been reading the VMS Tuning Guide provided (free) from Touch Technol-
ogies (they market the Dynamic Load Balancer).  The guide advises setting
MPW_HILIMIT (limit at which VMS starts writing pages from the modified
page list to disk.  Sets a limit on the MP list size) at 15 percent of the
size of physical memory.  The claim is made that the loss of physical
memory is more than compensated by a reduced paged I/O activity.
    This seems like a rather large number for this sysgen parameter,
as DEC set the default at 500 pages.  Has anyone followed Touch's advise?
Have you noticed a significant performance improvement?  We run large
images, use large pagefiles and often encounter applications where much
paging is required even with large WSEXT values.  I am thus trying to
evaluate whether increasing MPW_HILIMIT (and MPW_WAITLIMIT) is a
reasonable thing to do (our current setting is 655, physical memory
is 32768 pages and VMS already uses 4400+ of these).
    Any comments or other rules of thumb?

-Ric Steinberger
steinberger@kl.sri.com

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