Grand Unified Theory of SIMD

Glen Low writes " All of a sudden, there's going to be an Altivec unit in every pot: the Mac Mini, the Cell processor, the Xbox2. Yet programming for the PowerPC Altivec and Intel MMX/SSE SIMD (single instruction multiple data) units remains the black art of assembly language magicians. The macstl project tries to unify the architectures in a simple C++ template library. It just reached its 0.2 milestone and claims a 3.6x to 16.2x speed-up over hand-coded scalar loops. And of course it's all OSI-approved RPL goodness. "

Comments

Depends on what you are doing

[dsci]

We write code for hardcore chemical simulations. The limits on what can be studied, ie number of atoms/molecules or timescales of the simulations depends on one thing: speed.

Faster computers means better simulations. BUT, if the code is not as fast as it can be on a particular architecture, your simulations are not going to be as complete as they can be. At least within a given time allotment.

I've recently applied some code optimizations to a Monte Carlo simulation and saw speed ups of over 1000x. That's significant.

It's naive to think that faster computers means we should live with sloppy or unoptimized code. SIMD is a useful technique, and if it means the difference between me getting work done in a week or two or three weeks, I think I'll take the one-week sim.