Date : Mon, 06 Mar 2006 18:59:58 +0000
From : Fragula <fragula@...>
Subject: Re: Warning: Sad case on list!
Jules Richardson wrote:
> impressive, but making them *do* something tends to be a bit anti-climatic.
You must be doing it wrong! They are lousy word processors sure, but
give them the right problem...
i.e. an array of a million (or so) objects, each with perhaps 30
simplified properties, mass, size(thus density implied by a fairly
complex alorithm) temperature(depends on...), cohesion(depends on),
adhesion(depends on), X,Y,Z, positions, X,Y,Z velocities and heaven
knows what else. Calculate (using accurate scalar/vector/scalar
conversion) the cumulative gravitational effect of the other 999,999(or
so)objects, calculate the Delta-V for all 3 dimensions, calculate
updated positins for the next tick, check all the "rays" of movement to
check for potential collisions, check collision, effects of collistion
(merging, disintegration, bouncing, w.h.y) adjusting number of objects,
and properties of "revised" objects accordingly, translate the output
into a nice raytracing and add that to the output file(s)
Its not something PCs, even multiprocessor athlons or xeons, running
linux, are terribly good at.
Yet the late 80s Cray "entry level" machines, even with with its
386-like clock rate, due to its low latency non "predictive" (I'm not a
fan of SDRAM or DDR terribly, for that reason, latency) memory
architecture, and vector registers/multiple paralell ALUs sets can still
make the same ball park as the last generation of AMD desktop chips, or
the current generation of Intel , It can't touch the mighty Opteron (I
am a fan of these, in spite of the local memory technique) running a
compiled-for-the-hardware 64 bit Linux kernel and application.
The key is in using the right compiler (the Cray C compiler!) and using
a little intelligence when coding and compiling.
The Problem, if you like, with a supercomputer, is one of having a
superproblem.
I'm on basic PC duty now.. Have to scan and print large the scans of my
unborn grandchild.. "Baby's first pictures". I guess AMD boxes have
their uses after all.
Cheers!
M.