🚀 go-pugleaf

In article <nevin-0702960733520001@150.135.1.79>, 
nevin@CS.Arizona.EDU (Nevin ":-]" Liber) writes:

|> In article <4f6bag$ckp@news.mpd.tandem.com>, 
Joseph Crowe <jcrowe> wrote:
|> 
|> >    Here you hit on the one essential issue that probably causes all of the
|> > conflict in the PMT vs. CMT debate.  Essentially, with PMT, the OS controls
|> > what the app can do, such that the writer of the app should not have the
|> > capability of "taking over the machine". 

:
:

|> No.  There are some people you can't convince, no matter how much reason
|> and logic you use.  Example:  the Monty Hall problem on rec.puzzles (no,
|> don't discuss it here and for their sake, don't dicuss it there).  Some
|> people believe that the answer is 50%, not 66 2/3%, and that debate has
|> been going on longer than this one!  It doesn't matter how well you
|> present the correct solution to them, they are just too stubborn or too
|> dumb to get it.
|> 
|> The debate has gone something like this:
|> 
|> Don:  In a CMT environment, a non-cooperating process can starve other
|> processes.
|> Me:  You bet it can.  In practice, almost none of the applications exhibit
|> this behavior.
|> Dan:  But in a CMT environment, a non-cooperating process can starve other
|> processes.
:
etc.
:

|> At this point, I have to question their ability to reason.  I guess they
|> think the issue will magically become important if they keep repeating it
|> over and over and over and over and over and over and over.  Either they
|> just like to waste bandwidth (beer commercials made fun of these people in
|> the "Tastes Great"/"Less Filling" ads), 

Your critique is amusing, and your summary is *almost* correct:

                                          they don't have the intelligence
|> to figure out that this is an incredibly minor and trivial point, or I
|> don't have the intelligence to realize why this is so important 

It is not a question of intelligence, it is a question of carefully
analyzing the competing arguments.  Anyone with the intelligence to
understand exactly what CMT and PMT are has the intellectual capability
to understand the real issues.  Unfortunately, "religious" issues
sometimes restrict the possible solutions.

At this point, I will say that it is not a "trivial point".

                                                                    that the
|> 100 million of us that don't have it really can't live without it, even
|> though we are living without it.  

Billions of people live without running hot water, too.  *And* computers.


                                    It seems so obvious to me that processes
|> that don't cooperate in a cooperative environment can do bad things, and
|> applications that do bad things tend not to get used in favor of those
|> that don't do bad things.

There are several missing points to this oversimplification:

1) Under CMT, *all* the ruuning applications have to behave well,
even in future circumstances that are difficult to anticipate.
For example, I recently saw some applications affect the usability
of an active videoconferencing session on a PowerMac.  Now, you
could say that it is unfair to expect all apps to behave well
in the presence of videoconferencing applications, because such
new apps represent a new and very demanding requirement.  But, that 
is exactly the point: under a PMT OS, the applications are decoupled 
and new, demanding apps don't create demands on older, less-demanding 
apps.

2) Under CMT, there are programming costs incurred for development
on all cooperating programs, not just the most demanding ones like
videoconferencing.  In practice, this means that in the Mac world, 
Mac programmers tend to be "Mac experts" only (the same would be
true of any unique CMT environment).  In practice, this means
higher development costs and fewer packages that are portable 
across platforms including the Mac.

3) Just ask any OS developer whether they would ever do a new CMT 
OS again from scratch.  I wonder why all new general-purpose OS's
are more general?  The reasons for existing CMT and CMT-like OS's
are historical, not technical.  Ask the experts in any CS department.


As to what this means to the average Personal System (Mac, PC running
Windows 3.1) user, I don't pretend to know.  If you only run the usual
Excel, Word, and PowerPoint, one at a time, it doesn't much matter.




-- 
  Hugh LaMaster, M/S 233-18,    Email:       Please send ASCII documents to:
  NASA Ames Research Center     Internet:    lamaster@ames.arc.nasa.gov
  Moffett Field, CA 94035-1000  Or:          lamaster@george.arc.nasa.gov 
  Phone:  415/604-1056          Disclaimer:  Unofficial, personal *opinion*.