Path: utzoo!attcan!uunet!munnari.oz.au!brolga!bunyip.cc.uq.oz.au!oat!qut.edu.au!zseelunnon
From: zseelunnon@qut.edu.au
Newsgroups: comp.os.minix
Subject: Re: Virtual memory Minix
Message-ID: <1990Nov9.235558.20043@qut.edu.au>
Date: 10 Nov 90 04:55:57 GMT
References: <35678@nigel.ee.udel.edu>
Organization: Queensland University of Technology
Lines: 26

In article <35678@nigel.ee.udel.edu>, HBO043%DJUKFA11.BITNET@cunyvm.cuny.edu (Christoph van Wuellen) writes:
> To contribute to the paging discussion:
> 
> Remember that paging must not mean that parts of the virtual memory are
> swapped to a disk.
> Paging may simply mean that you can allocate memory to processes in a
> flexible way by translating virtual to physical addresses
> by means of pages, thus solving the chmem problem.
> 
> If 68000, 68010, 68020, 8088, 8086, 80286 are gone, AST will not be
> against THAT.
> 

Hmm, I have been thinking, for the 68K it would be possible to page to disk
memory belonging to idle processes on a task switch leaving all available
memory for the running application, thus a 68K minix would be able to run
several processes larger than the physical memory size. If two processes own
the same block of memory (that is an in-core process and the next process ) 
then the whole or part of the in core process could be swapped out to make
room this could also happen if malloc was called. The only real problem
here is that once the processes own the same block , swapping WILL occur on
invocation of each of the processes until one frees the common memory block
(as it is not possible to move data around :-( ).


> C.v.W.