Path: utzoo!attcan!uunet!tut.cis.ohio-state.edu!ucsd!usc!apple!sun-barr!newstop!sun!nubbins.Eng.Sun.COM!martyi
From: martyi@nubbins.Eng.Sun.COM (Marty Itzkowitz)
Newsgroups: comp.arch
Subject: Re: Tradeoffs
Message-ID: <136844@sun.Eng.Sun.COM>
Date: 7 Jun 90 20:22:16 GMT
References: <640@sibyl.eleceng.ua.OZ> <2662CE6C.3E68@tct.uucp> <26798@eerie.acsu.Buffalo.EDU> <266576A7.6D17@tct.uucp> <9494@pt.cs.cmu.edu> <1990Jun3.041822.13548@utzoo.uucp> <27416@eerie.acsu.Buffalo.EDU> <.5X3-ZB@xds13.ferranti.com> <671@sibyl.eleceng.ua.OZ>
Sender: news@sun.Eng.Sun.COM
Reply-To: martyi@sun.UUCP (Marty Itzkowitz)
Organization: Sun Microsystems, Mountain View
Lines: 27

In article <671@sibyl.eleceng.ua.OZ> ian@sibyl.OZ (Ian Dall) writes:
>
>Dunno much about Jove. One feature of GNU emacs which not many of its
>competitors offer is online documentation. I've no doubt that GNU
>emacs would be a *bit* smaller if totally rewritten instead of having
>grown over such a long period. In a running emacs it is easier to get
>a process size of over 2MB. Most of this is due to the number of files
>visited. In some ways, emacs method of reading in all of every file
>visited seems wasteful, but in practice it is not too bad. One
>alternative is to make (allow) the user two only read in "pages" of a
>file at a time. That is certainly workable, but is not transparent.
>Another alternative is to automatically read in sections of files as
>necessary and, if necessary, write out data to temporary files.
>Surprise, surprise, that is almost exactly what a virtual memory
>operating system does. So why not *let* the virtual memory operating
>system do it? (*) Why does it matter that "ps" shows a large number for
>the process size?
>

The main argument for NOT letting the virtual memory system deal with it
is that the program has a much better idea of an appropriate strategy
for page replacement than the OS can infer from past behavior.  When the
user switches to a new file the editor can infer that the pages from the
previous edit can be discarded, whereas the OS will assume that if
they were recently used they ought to be kept.

	Marty Itzkowitz