Subject: Pointers to VM documentation
To: None <tech-kern@NetBSD.ORG>
From: VaX#n8 <>
List: tech-kern
Date: 06/07/1995 15:29:24
I need some references on how the VM system of NetBSD works.
I have the Leffler et. al. book for 4.3, but I'm not sure how close
NetBSD is to it.  Should I get the Bach book on System III?  Where do I start?

Please send replies directly to me; I am unsure that I am subscribed to
the mailing list.

FWIW, this is in reference to my earlier post to current-users about a
compression VM system.  I finally decided on that as my course topic and
now I've got to decide whether to do it for NetBSD, Mach, or Linux.
My current inclinations are towards NetBSD.

If you're interested in the topic, I can summarize results.

Performance issues are addressed in Douglis' paper in 1993 Winter USENIX,
which gives a speedup of 2-3x on a Decstation 5000/200 with local disk.
As he states there, better speedups would occur when you have greater disparity
between CPU speed and backing store bandwidth (esp. on mobile computers that
have high disk latency (spinup)).

The typical compression routines work on small blocks and hence can't use
LZW-type dictionaries; they are tailored to the domain they work on.
E.G. long runs of zeroes, pointers to close regions of heap-allocated space,
etc.  We're not talking about building huffman trees or anything.
VaX#n8 (vak-sa-nate) - n, CS senior++ and Unix junkie -
Deal with evil through strength, yet encourage good through trust.    - PGP me