Re: Execution speed of current snapshot vs. official 2.1.1

[Paul Johnson]

M Lang / S Railsback wrote:
> Marcus: I remember you doing some work to speed up Swarm. 
>
> I am running our fish model using the official release of 2.1.1, dated
> Oct. 2000. The model spends most of its time in our Objective C code,
> and we did speed it up about 20% by eliminating unnecessary calls to
> time-consuming functions like EXP() and POW(). However, we do a lot of
> messageProbe calls too. 

Yes, there are some speedups I'm sure of. About 6 or 8 months ago I 
goosed Swarm's use of random numbers, and some programs I ran got 25% 
faster. On average, I think Marcus saw about a 12% improvement.

I did not realize exp() and pow() are bad.  I notice really big 
performance improvements from getting rid of modulus operators in my 
code.  I can make Obj-C heatbugs run about 1/3 faster by fiddling the 
space so it does not use % so much. In case you ever want to see, please 
drop this new one in and measure:
http://lark.cc.ukans.edu/~pauljohn/Swarm/MySwarmCode/HeatSpace.m

One speedup I have obtained recently is in avoiding slow usages of Swarm 
List objects. If you use atOffset:, it starts at the beginning and 
counts through until it finds what it wants.  doing a for loop with 
atOffset: in it is humongously slow.

When atOffset is unavoidable, I find converting to Swarm Arrays makes a 
pretty big difference, especially in randomly permuted lists or in 
randomized action groups.  It makes such a big difference because the 
Shuffler uses atOffset a lot in grabbing elements from the list.

Let me know what you think about the new swarm pretest. I get good 
performance, especially from Java apps the speedup is quite dazzling.
--
Paul E. Johnson                       email: address@hidden
Dept. of Political Science            http://lark.cc.ku.edu/~pauljohn
University of Kansas                  Office: (785) 864-9086
Lawrence, Kansas 66045                FAX: (785) 864-5700


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