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From: chewy@apple.com (Paul Snively)
Newsgroups: comp.sys.mac.system
Subject: Re: PPC, IAC, and True Multitasking (tm)
Message-ID: <9842@goofy.Apple.COM>
Date: 20 Aug 90 21:00:53 GMT
Sender: usenet@Apple.COM
Organization: Apple Computer, Inc.
Lines: 30
References:<1990Aug3.040513.14844@d.cs.okstate.edu> <2760@bridge2.ESD.3Com.COM> <13888@cbmvax.commodore.com>

In article <13888@cbmvax.commodore.com> valentin@cbmvax.commodore.com 
(Valentin Pepelea) writes:
> An operating system has a pre-emptive scheduler, or it doesn't
> have one at all. There is no such thing as a cooperative scheduler. The 
term
> cooperative is used when there is an absence of a scheduler.

Wrong.  It's quite possible to have a cooperative scheduler; all it means 
in the case of the Macintosh is that some events are of higher or lower 
priorities than others (for example, in the forthcoming System 7.0 
release, High-Level Events will have a higher priority than user-initiated 
events, so that AppleEvent throughput will be at an acceptable level).

Of course, in a cooperative environment, each "cooperating" entity still 
has the opportunity to be rude and be a CPU hog; the cooperative scheduler 
simply means that once the hog _does_ relinquish control, it may be a 
while before it gets control back again, and how long "a while" is depends 
partially upon the scheduler and partially upon just how cooperative 
everything else running is being.

__________________________________________________________________________
                                Paul Snively
                      Macintosh Developer Technical Support
                             Apple Computer, Inc.

chewy@apple.com

Just because I work for Apple Computer, Inc. doesn't mean that I believe 
what they believe, or vice-versa.
__________________________________________________________________________