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From: mouse@thunder.mcrcim.mcgill.edu (der Mouse)
Newsgroups: comp.unix.sysv286,comp.unix.sysv386,comp.unix.xenix.misc,comp.unix.xenix.sco,comp.unix.wizards
Subject: Re: Kernel Definition
Message-ID: <1991May24.065316.27331@thunder.mcrcim.mcgill.edu>
Date: 24 May 91 06:53:16 GMT
References: <1423@necis.UUCP>
Organization: McGill Research Centre for Intelligent Machines
Lines: 25

In article <1423@necis.UUCP>, jjp@necis.UUCP (Jeff Phillips) writes:
> A friend of mine is writing a paper on balanced system approach.  In
> it he makes the assertion that "...(the UNIX operating system is) too
> large to fit in system RAM all at once, [...]"

This is true only if the term is interpreted very broadly.  All UNIXish
systems I know of keep the kernel permanently resident; you have to
take "the system" to include things like the shells and compilers and
other utilities for the statement to be true.

Someone else pointed out that u-areas and kernel stacks are swapped
and/or paged in some UNIX(ish?) systems.  This is probably true but is
sort of irrelevant, since they would *fit*, it's just that the system
believes it can make better use of the space - and the statement was
that things wouldn't fit.  One can also consider those as part of the
process, and nobody argues that processes have to be swapped.

As an aside, I've used systems (well, a system - a Sun-4/something)
which had as much RAM as swap space.  Sure made for snappy response.

					der Mouse

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