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From: kdarling@hobbes.ncsu.edu (Kevin Darling)
Newsgroups: comp.sys.amiga
Subject: Re: Multitasking at home (Was Reality check: ....)
Message-ID: <1990Dec27.164630.10864@ncsuvx.ncsu.edu>
Date: 27 Dec 90 16:46:30 GMT
References: <54.27730FA6@ijcr.fidonet.org> <186801ce.ARN0872@easy.UUCP> <1990Dec24.132204.17059@ncsuvx.ncsu.edu> <186ab528.ARN08a6@easy.hiam> <186abe5f.ARN08a9@easy.hiam>
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Organization: NCSU Computing Center
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In <186abe5f.ARN08a9@easy.hiam>, Dwight Hubbard writes:
>> In <1990Dec24.132204.17059@ncsuvx.ncsu.edu>, Kevin Darling writes:
>> Change the program a bit: write one which simply loops with no I/O at all,
>> and then boost the priority on it under Amiga Exec to be highest.
>> What happens to multitasking then?
>
> Same thing as would happen under Unix or OS/2 it dies.

First, hope you had a good holiday!  Second, I thought the answers people
gave to the original "true" question were very good, and pointed out that
preemptive multitasking gives a real, tho sometimes subtle, advantage.
My impulse for posting that obviously leading question <g> was to note
that there _are_ layers of subtlety involved when it comes to defining
"true multitasking"... especially in what it means to an end user.

For instance, the stated example shows that a higher priority task
under Exec with no I/O becomes exactly like a similar Mac process: it
must give up control explicitly... something some of us would not consider
"true" multitasking.  Or at least, not as user-nice.  Under OS9, all
processes also "age", and eventually get a chance to run.  Even OS/2 has
a settable timeout to prevent one process from locking out the others.

There are other subtleties, but I don't want to bore or start flames :-).
So here's just some random comments:
 1. To many users the distinction between "true" and "fake" multitasking
    is just a techie question.  Faking can come close enuf for some.
 2. Every OS has cases where things degenerate away from "true m/ting".
 3. It's hard to drag people away from what they use now.  Good example:
    would you give up all your current Amiga programs in order to switch
    to, say, OS-9, which might (/not) have "truer" multitasking?  Doubtful.

In other words, as much as I've proselytized for (and used) preemptive
m/ting on micros long before even Exec came around, the distinction gets
blurry sometimes in actual use.  But then, you and everyone else pointed
that out yourselves... my article was a time-disjointed reply which
should (along with this one) be passed over, really.  Just wanted to
explain them a bit now.  Cheers - kev  <kdarling@catt.ncsu.edu>