Slashdot Mirror
Software to Make Blue Gene Top 200 Teraflops
An anonymous reader writes "New Scientist has a story about the most intensive computer program ever created. It runs on IBM's big beast, Blue Gene/L, at Lawrence Livermore National Laboratory in California and carries out 207.3 teraflops (trillion cacluations per second). The program, called Qbox, performs very complex quantum calculations to simulate the behaviour of thousands of atoms in three dimensions. Wow."
So in essence, it takes about .2 teraflops per atom... And that was only after spending a lot of time condensing the algorithms. This makes me wonder two things. First, what do these equations look like such that it takes 200 gigaflops just to model one atom. Second, over what timeframe does this simulation take place? Are we talking real-time, calculating for 50 years, what?
Regardless, as a computer scientist, I say way to go to these guys, this is damn impressive.
Government's view of the economy: If it moves, tax it. If it keeps moving,regulate it. If it stops moving, subsidize it.
Thats actually quite simple.
If they are modelling everything without calibration from known experimental results then anything this machine can produce is as trustworthy as internet gossip.
For instance, if you were creating a weather prediction machine (easier to explain), you would feed it with all your historical data and allow the calculations to run from a set date in the past. If the results matched up with actual observed results for the following day/week/periods then you begin to build confidence in your algorythm.
You continue this and allow it to calculate longer and longer runs, most likely tweaking your code as you go along.
To put it into real perspective, heres the real version of the simulated experiment.
liqbase
Cell was designed around one single objective - to get a clock rate as sickeningly high as possible, because clock speed cells. Trust me when I say that programmability was not (at all) a consideration (I should mention - my research group got one of the very first Cell processor's sent to the US. We are currently in the process of implimenting OpenMP on it to make it a little nicer to program).
As far as writing multi-threaded code, I've spent the last 5 months rewriting the NAS CG benchmark to work effeciently on Cyclops64, which will probably play some part of my PhD thesis. (A sidenote: All of NASA's NAS implimentations are written in Fortran (except Integer Sort), which would have necessitated me rewriting NAS-CG in C. Fortunately, I didn't have to start from scratch, because the Japanese had already done the hard part).
To make laws that man cannot, and will not obey, serves to bring all law into contempt.
--E.C. Stanton
At the unfortunate risk of repeating myself on Slashdot (Oh, the Humanity!) you are correct. It is intrinsically impossible for a discrete-state system to model quantum mechanical events, unless you somehow sneaked under the Planck limit (There is no spoon..) So, they're faking it.. However, if it is a good model of "reality", then it is good science. If it can predict, it is useful.
I don't trust atoms -- they make up stuff.
Thousands of atoms. Shrodingers/Bohrs equations for all of them.
This has interesting consequences for the study of plastics, DNA, virii and other complex molecules.
Perhaps the program can run in a loop trying every possible atomic combination to produce the best of certain attributes, as in give me the hardest material or give me an easy to manufacture room temp superconductor. It bypasses the whole invention/discovery step.
"Give orange me give eat orange me eat orange give me eat orange give me you." -Nim Chimpsky