Path: utzoo!attcan!uunet!husc6!cmcl2!brl-adm!brl-smoke!gwyn
From: gwyn@brl-smoke.ARPA (Doug Gwyn )
Newsgroups: comp.unix.wizards
Subject: Re: When did paging get into System V
Message-ID: <7878@brl-smoke.ARPA>
Date: 12 May 88 19:42:14 GMT
References: <53@lazlo.UUCP> <142700033@occrsh.ATT.COM> <651@pyuxe.UUCP> <382@cloud9.UUCP>
Reply-To: gwyn@brl.arpa (Doug Gwyn (VLD/VMB) <gwyn>)
Organization: Ballistic Research Lab (BRL), APG, MD.
Lines: 14

In article <382@cloud9.UUCP> bob@cloud9.UUCP (Bob Toxen) writes:
>About five years after Berkeley came out with it!

So?  Performance tests showed no significant performance advantage of
demand paging over the then-current UNIX System V scheme of partial
swapping.  It was not until the additional advantages of an organized
scheme like the UNIX System V region-oriented approach became apparent
(e.g. shared libraries) that there was reason enough to implement it.
Conversations I've had with kernel implementors indicate that, modulo
a few glitches that can be readily corrected, the UNIX System V scheme
(which resembles VMS's) is on the right track, and that Babaoglu's
scheme embedded in 4BSD often has to be totally replaced.  (Sun
designed their original memory management hardware to look virtually
the same as the VAX's, to avoid this.  Not everyone has had that option.)