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."
How do they know they got it right?
Slashdot.. where people join together in deliberate ignorance.
So you're a computer scientist, but you apparantly don't understand Big-O notation or the concept that algorithms don't neccesarily scale linearly with the number of elements.
C64 takes a totally different approach to high performance computing. Most supercomputer architectures are built around a moderate to large number of very, very fast (and power-hungry) processors. For example, Big Mac at Virgina Tech had something like 10,000 pentium 4 class processors. Cyclops64 is have an *enormous* number of processors (on the order of a million), but running only at 500 mhz, making them much easier to cool). The idea is to give the programmer more thread units than he knows what to do with, running very close together at a low level.
To make laws that man cannot, and will not obey, serves to bring all law into contempt.
--E.C. Stanton
Because those atoms do their things on VERY short timescales. There's no way you can probe what they're doing on short enough time (and length) scales, even with pump-probe laser experiments, and track movements. Possibly, in some very special circumstances, you can look at beginning and ending states, and then figure out intermediate states. However, in general, this isn't possible, and so we need such simulations to track in-between processes, especially in ergodic systems.
Because they are apparently simulating them under extreme conditions that are present during nuclear explosions. And nuclear tests are banned.
Save the bandwidth. Don't use sigs!
Sorry, but I imagine you'd keep one of the many processors very busy, with the rest left idling away.
Now, spawn a thread for each processor running this, and you might have something =-)
The compiler [the current version, at any rate] is based on gcc. So it sports the same out-of-order execution you would expect to get from compile-time optimization. I am not sure if it has hardware-based re-ordering. My guess would be that no, it does not, but without the Principles of Operation in front of me, I couldn't say (the advisor borrowed my paper copy for IPDPS 2006 and hasn't given it back yet).
To make laws that man cannot, and will not obey, serves to bring all law into contempt.
--E.C. Stanton
Imagine, if you will, taking this super-computing ability out a few years. Can the U.S. justify the invasion of a country X because X successfully simulated an attack on the U.S? Or maybe they just had the computing power to simulate it.
To the UN: We'd like you to look at these satellite images that clearly show a super computer simulating the destruction of the U.S. We have to take out these terrorists and we're willing to go it alone.
Afterward: Well it turns out that they didn't have the computing power at all, the images we had were of a mobile home park.
Bzzt Whir Click
The *real* sad truth is that inspite of the arrogance of some people, not voting the way you do does not mean that people are stupid, evil, or mindless. It just means they disagree with you.
when you already control everything, you don't HAVE to be loud.
As for obnoxious, well, that's in the eye of the beholder. For example, I consider monitoring my phone calls and locking people up without due process to be pretty damn obnoxious. But that's just me.
-Eric
SJW: Someone who has run out of real oppression, and has to fake it.
impossible for a discrete-state system to model quantum mechanical events
Huh? QM was a while ago, but I'm afraid you'll have to give a reference or two. You're saying that Density Functional Theory is impossible? The authors (of DFT) did win the Nobel proze a while ago, so I'm sure I'm missing something. Mind you, any implementation is only an approximation, but that's true of almost any computational method.
Yes. I am am saying that a discrete-state-system, such as a Markov chain, cannot follow quantum mechanical events. QM state reduction is not beforehand deterministic because it it follows a wave function that be known beforehand in its full vector state (e.g. position and velocity.) If you wish references I would need to look them up, except for my remembrances of Richard Feynman and Stephen Hawking lecturing to me on this subject, and my own experiments. But I can find them. That neither obviates your point or mine. My background is in physics but I work in computer science, and good-enough computational approximations have a way of being "good enough". Perhaps our argument is about "truth", which we model only imperfectly. Or then, perhaps we have no actual argument at all. Oh, DFT is a good and very useful theorem and practical model, but it does does sidestep the issue of QSR in some cases, as does almost any model of QM. Thx.
I don't trust atoms -- they make up stuff.