Anywone write anything about efficiency and space?

[Paul Johnson]

I keep wondering about RAM and efficiency in designing Swarm projects, 
and wondered if anyone had written about it.  Here's part of the reason
I am concerned.

Several years ago, I wrote a simulation in the SAS macro language that
ran on a mainframe, I think it was an Amdahl.  That took hours, so a 
consultant said I should just write it in Pascal and run it on a 486
and it would be much faster.  So I spent a few months learning Pascal
and finally got a simulation running, but then CLUNK, there were inherent
limits that stopped me from scaling up the size of the project. I was
using Borland Pascal 7.0, not exactly a piece of crap. As I recall, there
were two major problems. One was that there was a strict upper limit on
the number of variables that could be introduced.  Second, there was a limit
on the size of an array, or the number of items pointed to by an array.
No matter how much RAM you have, you can't have an array with more than
a certain size (was it 64k?). 
There were some work-arounds for the array problem, but as I recall
they did not scale with the parameters easily, and I was stuck with
a middle sized model.

Working with Swarm, I've learned a bit about C and ObjC and haven't heard
any talk about limits on array size or such. What a relief!  But I still
keep wondering if I am going to hit such things.  

If somebody does think about writing something, here are some of the
specific questions I would like to ask:

1.  Suppose I create an object, and it has several int and float variables.
Suppose I then create 3 lists, and add that object to each one. That doesn't
create 3 copies of the object, does it? How much RAM is used? 
2. In the docs on Arrays and lists, there are some comments about
speed, but, since I'm not a programmer, I don't understand them very well.
Care to elaborate?
3. Maybe this is too vague, but I keep wondering whether it is better/faster to
design an object that has many methods that it can perform sequentially or
several objects, each of which performs one method, each of which is called
sequentially?   Know what I mean?  It seems like the one big object might
have less message passing, since the object has command of all instance 
variables inside it.  However, such code is not so elegant and useful
in other projects.
4. I remember reading several months ago about a way to run a program
and then measure the amount of time the CPU spent on each task.  One could
look to see where gains in program speed might be had.  But I
cant even remember if that was in Linux, or on an Alpha system, or what!
Anyone remember it?

Paul E. Johnson                           address@hidden
Dept. of Political Science                Office: (913) 864-9086
University of Kansas                      FAX: (913) 864-5700
Lawrence, Kansas 66045                    Home: (913) 842-9916                  
   


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