From: petesk@microsoft.com (Pete Skelly)
Subject: Re: How many NT developers does it take to boil water?
Date: 06 Oct 92 00:35:55 GMT
Organization: Microsoft Corp.

In article <1992Oct5.162850.22360@njitgw.njit.edu> dic5340@hertz.njit.edu wrote:
> In article <1992Oct03.232108.18990@microsoft.com> petesk@microsoft.com (Pete Skelly) writes:
> >Sit down to do something like, say, your income taxes.  Get one of those
> >kitchen timers, and set it for 5 minutes.  Do your taxes.  When the
> >bell goes off, reset the timer, and go read the newspaper.  When the bell
> >goes off, reset the timer again, and watch TV.  and so on, and so on.
> >
> >If you don't scramble your brains after a while, I'm impressed.
> 
> Are you implying that this will scramble a computer?  You don't have
> to be on a timer to work preemptively, and nobody said that they do
> this ALL THE TIME.  Some jobs actually require thought.  And I CAN
> cook lunch and do taxes at the same time - with a timer.

No, I'm implying that comparing peoples ability to "multitask" to a
computers ability is not a good comparison.  As for cooking lunch, that's
an IO bound task, which is where threads are useful.  It does not require
preemptive multitasking though.

> 
> >Now, also, in your boiling water deal, wouldn't you much more prefer to
> >set a timer, or have some sort of an alarm that goes off when the
> >water is boiling.  I find it distracting to have to go back to check
> >on boiling water more than one or two times.
> 
> Wow.  You have water that always boils on schedule.  If you set a
> timer, it's still likely that the water won't be boiled, or will have
> boiled for too long (evaporating much of it).  You still have to check
> back every so often.

I don't, but most computer I/O tasks do.  They are called interrupts,
and most I/O devices send an Interrupt when they are done, so I don't
have to keep swapping through each of the processes that is processing
the I/O.

> 
> >Now, if you did have an alarm of that type, wouldn't boiling water be
> >more equivalent to sending a request to the disk controller, and then
> >servicing the interrupt it generates when it's done.
> 
> Preemptive systems work much like harware interrupts.  But you can't
> really replace one with the other.

You are correct, but thats not really the point.  Let hardware interrupts
take care of I/O notification.  Why have preemptive MT do that.  Let
preemptive MT do what it's good at.  Let non-preemptive do what it's good
at.  Just choose the right method for the job.  It's rather silly
to think that one or the other is going to work for all, or even most
cases.

> 
> >Okay, I've gone off on sort of a tangent here, but I guess I've tried to
> >point out that preemptive multitasking is not the only method for doing
> >things in the real world, as well as in the computer world.  And in some
> >cases, it's not the best.
> 
> Who said it was?  But it's obviously better that you're admitting or
> it wouldn't be used in all medium-to-high-end multitaskers.

Could it be that the medium-to-hight end systems are doing tasks at which
preemptive multitasking is good at?  Does that mean that preemptive multitasking
is automatically good for low end systems to.  And for palm tops, and for
notebooks, etc...

Those are not exactly small markets (or predicted markets).


petesk@microsoft.com
My Opinions...
Newsgroups: comp.os.os2.advocacy