🚀 go-pugleaf

Nevin ":-]" Liber (nevin@CS.Arizona.EDU) wrote:
: In article <19960204.10AE3B8.A1B8@olympus.net>, dons@olympus.net (Don
: Schmelling) wrote:
: 
: > What is this facination with the term "Real Life?"
: 
: I don't find trivial things that don't occur in practice to be all that
: interesting.  I work on real systems.  Theoretitians and geeks might find

Is not life a "real system?"

: these endless debates about trivial problems to be enlightening in some
: way, but I don't.  Interesting problems inspire me to think about them. 
: It's fairly obvious to me that when you program a CMT based system, you
: have to give up the CPU in order for other processes to execute.  It
: didn't take much brain power on my part to come to this conclusion.  Maybe
: it excites your brain cells.  Maybe you think that you have discovered
: something so fundamental to the foundations of computer science that if we
: ignore it we'll all go down in flames.

You are right it is obvious that you have to give up the CPU in a CMT
system for another process to execute.

But that does not change that fact that this very thing can completely
bring multitasking down in a CMT model.
: 
: This is the part I find interesting:  why does people think that this
: issue is interesting and has enough substance to spend more than a few
: seconds thinking about it?  In other words, I'm in it for the meta-debate.

Because, you are completely uncompromising.
You just will not admit that when a task is taking up all of the cpu
time that you are no longer multitasking.
: 
: > I never said that you could not break out of this program.
: > I was attempting to say, that while this program is running
: > you are not multitasking.
: 
: Well, I obviously am on some level, since the mechanism that allows me to
: break out of this program is not part of the infinite loop itself.  The
: clock on my menu bar updates also.  Now, my system may not automatically
: go to another high-level process, but it certainly allows other
: lower-level tasks to continue executing.

No.  An interupt is not a task.
: 
: > Now perhaps eventually an interupt
: > can take place,
: 
: What do you mean by eventually?  I'm not blocking them, so what would
: cause them to delay?

I am sure that you have had the unfortune to write a program with an
anfinite loop in it.  If you try to stop the process it does not
terminate instantly.
: 
: > but for all the time between then you are
: > not multitasking you are running ONE TASK.
: 
: But that is always true unless you have more than one processor!

I will agree with you here.  However, a PMT model switchs processes
rapidly enough to give the illusion that this is happening.
A CMT model will allow a process to take over the cpu for long
peroids of time thus making the illusion transparent.
: 
: > : And I have yet to find a reason to run programs this badly written.
: 
: > That really is not the issue.
: 
: Of course it is the issue.  Programming is a contract between the
: programmer and the OS.  If the programmer breaks the rules, bad things
: happen.  I have yet to use a system that has absolutely no rules at all.

The issue is that with a PMT system there are not the amounts of
programmig rules that a CMT system has in order to have effective multitasking.

: 
: > The issue is that a badly written program
: > can hog the cpu on a CMT system while on a PMT system the program is
: > given a certain amount of cpu.
: 
: That is because one of the rules of programming a CMT system is that you
: have to give up time for other processes to run.  Duh.  Are you really,
: truly, honestly so dumb that you don't understand this?  If you really
: don't, then you are too stupid to be programming a Mac or Windows or DOS
: machine.

See above.
: 
: What happens on your Amiga if I raise the priority on for (;;); so that it
: is higher than everything else?  Are you still multitasking?  If not, then
: the Amiga is just as broken as CMT systems.  If yes, then there is no way
: to guarantee that you won't be switched out, which can also be a bad
: thing, depending on what you are doing.

yes you are still multitasking.  True the task with the higher
priority will get more of the cpu time.  However, it will still
surrender the cpu after its quantum is up.

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Don Schmelling   Port Angeles, WA USA |
    A1200/540/CD + A1230 50/50/8      | "Don't blame me, I voted Republican"
           OMNIA EXTARES              |
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