🚀 go-pugleaf

In article <9711@batcomputer.tn.cornell.edu>, thompson@batcomputer.tn.cornell.edu (Steve Thompson) writes:
> In article <119@hammer.UUCP> jockc@idsila.com (Jock Cooper) writes:
> >I have this ray tracing toy that runs faster on our MicroVax 
> >(has FP coprocessor) than on my DECstation 3100. Does the 3100 
> >have a Floating Point chip or what? Or is it an option?
> 
> Well, I have two main applications that I run on a VAXstation 3100 and
> a DECstation 3100, using the SAME source code in both cases (it's
> fortran). They are a Monte Carlo and a Molecular Dynamics simulation
> of a fluid stucture. The MC code is 10% faster on the VAXstation than
> on the DECstation, and the MD code is 4 times faster on the DECstation.

Differences this great on programs whose style of computing is probably
reasonably similar (compared to programs using lots of strings or packed
decimal) suggest either machine memory differences (that one of the
machines is running out of memory and either paging to death or not
able to create a large enough temporary store to achieve the maximum
effect) or compiler differences (at least one of the programs has a 
code sequence that one or the other compiler isn't able to optimize).

My guess (since the DECstation is generally considered to be faster)
is that is that either the DECstation memory is underconfigured or
the compiler isn't as intelligent as the VMS compiler.

Comments?

						Bruce C. Wright