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From: dave@cs.wisc.edu (Dave Cohrs)
Newsgroups: comp.unix.wizards
Subject: Re: Berkeley paging
Message-ID: <5754@spool.cs.wisc.edu>
Date: 16 May 88 15:21:42 GMT
References: <53@lazlo.UUCP> <142700033@occrsh.ATT.COM> <651@pyuxe.UUCP> <7878@brl-smoke.ARPA> <11484@mimsy.UUCP> <7891@brl-smoke.ARPA>
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Reply-To: dave@cs.wisc.edu (Dave Cohrs)
Organization: U of Wisconsin CS Dept
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Even if you were to put a real working set scheme (or even WS-clock,
which might satisfy the spirit-of-UNIX argument you guys brought up)
into UNIX, you'd still need some kind of global policy.  You don't want
one process to take over all of memory; remember, working set isn't
fixed sized (which is why the VMS policy isn't really working set, or
wasn't last time I checked), it's defined over a time interval.  A
memory load balance policy is necessary, and you still need to swap
processes when memory gets over-committed.

If you have the hardware support, working set, or WS-clock would
probably be a win, even in UNIX.  Of course, if your machine doesn't
have enough memory in the first place, no memory management policy is
going to help; you'll need to spend some $$.

Rule #1 in paging:  It's great until you have to use it.

--
Dave Cohrs
+1 608 262-6617                        UW-Madison Computer Sciences Department
dave@cs.wisc.edu                 ...!{harvard,ihnp4,rutgers,ucbvax}!uwvax!dave