Path: utzoo!utgpu!news-server.csri.toronto.edu!mailrus!cs.utexas.edu!usc!elroy.jpl.nasa.gov!decwrl!nsc!taux01!amos
From: amos@taux01.UUCP (Amos Shapir)
Newsgroups: comp.arch
Subject: Re: Personal OS
Message-ID: <3937@taux01.UUCP>
Date: 31 May 90 16:22:52 GMT
References: <76700219@p.cs.uiuc.edu>
Organization: National Semiconductor (IC) Ltd, Israel, Home of the 32532
Lines: 39
X-Hdate: 8 Sivan 5750

In article <76700219@p.cs.uiuc.edu> gillies@p.cs.uiuc.edu writes:
|It seems from looking at the source code in UNIX, that correctness and
|robustness are halfway down the list of programmer priorities for that
|system.  The programmer expects that the separate address spaces gives
|him artistic license to write flakey software.  He expects to be saved
|(from a system crash) by a process crash.  He has no clue that the
|system can run out of (swap, file) space.
|
|Sure you need separate address spaces under UNIX, because the system
|software is of such low quality.

That's a gross exaggeration to say the least.  Most of the software
that constitutes Unix is well written and debugged, mainly because
programmers did not have to worry about crashing the system by the
slightest typing error.


|
|
|Do you presume that because there are 65 processes on your machine,
|that they must all be necessary?  In fact, most of them are probably
|kluges to deal with the separate address space problem in UNIX.  The
|UNIX philosophy is, "we care enough to have a process sniffing at it
|every half hour" (or N seconds).  While this would work in the old
|days, when there was only a very slow Cron(8) demon, today
|workstations talk to networks and are unbuffered interactive devices.
|There is no sanctioned way (under UNIX) to write software that
|notifies all interested parties (unknown at compile-time) in the
|system.

The fact that *you* don't know how to do it, doesn't mean that it cannot
be done.  There are a lot of ways for user-level processes to be informed
of events without resorting to the common address space quagmire.  A separate
address space is a "problem" only for those who don't know how to use it.

-- 
	Amos Shapir		amos@taux01.nsc.com, amos@nsc.nsc.com
National Semiconductor (Israel) P.O.B. 3007, Herzlia 46104, Israel
Tel. +972 52 522408  TWX: 33691, fax: +972-52-558322 GEO: 34 48 E / 32 10 N