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From: pcg@aber-cs.UUCP (Piercarlo Grandi)
Newsgroups: comp.unix.i386
Subject: Re: Question about memory
Summary: 1 meg per user when the average executable < 100K?
Keywords: memory, swap
Message-ID: <1723@aber-cs.UUCP>
Date: 11 Apr 90 22:27:48 GMT
Reply-To: pcg@cs.aber.ac.uk (Piercarlo Grandi)
Organization: Dept of CS, UCW Aberystwyth
	(Disclaimer: my statements are purely personal)
Lines: 29

In article <1990Apr11.024731.11955@nebulus.UUCP> root@nebulus.UUCP (Dennis S. Breckenridge) writes:
  In article <156@cms2.UUCP> alan@cms2.UUCP (Alan McCain) writes:
  > memory in their system.  They said that when their system goes into swap it
  > never seems to come out of it completely, even when everyone logs off.  I
  > have the same situation.  Whey does this happen and can it be fixed?

  If memory is a problem BUY MORE memory! A rule of thumb for the 386
  machines running a UNIX (not Xenix) kernel is 4 megs for o/s and 1 meg for
  every Simultask user. If all of your apps are *nix, then take your best
  guess, you are safe with 1 meg per user. 

The problem is not memory, is the stupidty of the swapper (and who wrote it,
or failed to rewrite it). Look again at your figures: 1 MB per user is also
more or less what all vendors recommend.

Now ask yourself: how many user processes approach 1 MB in *size*? how many
user processes have a working set approaching 1 MB? How much memory should
be left unused to avoid the problems with the System V swapper

The answer to the latter question is ******80-90%******. If you configure
your system with less than 5-10 times the memory required

	(avg.no.of.processes*avg.process.wkg.set)

the System V swapper will make your life miserable.
-- 
Piercarlo "Peter" Grandi           | ARPA: pcg%cs.aber.ac.uk@nsfnet-relay.ac.uk
Dept of CS, UCW Aberystwyth        | UUCP: ...!mcvax!ukc!aber-cs!pcg
Penglais, Aberystwyth SY23 3BZ, UK | INET: pcg@cs.aber.ac.uk