The G word isn't Grid anymore

Green500 BoF

Grid isn't the hot buzz word in HPC anymore, it is "Green". This is evident by walking around the show floor and seeing how many vendors are touting the "greenness" of their solutions.

With the increased pressure on reducing our carbon footprint, there is now a movement to not only improve the speed of the fastest computers in the world, but to also improve the efficiency with regards to power consumption. If power consumption continues to grow at the current rate (linear or even superlinear) with respect to performance, in the near future a large top-10 cluster could conceivably require its own power plant to operate. There is a desire to level off the power consumption of these large supercomputers and be able to increase performance without increasing power requirements.

The Green 500:
The metric is flops per watt, with the Linpack benchmark, and the system must make the normal Top500 list to be ranked. This list, which I believe was started last year, lets us know how the fastest computers in the world rank when taking power consumption into account. Perhaps making the top of the Green 500 will come with the same prestige as making the top of the Top 500. The major topic of this BoF is how the Green 500 should be redesigned to provide maximum utility. What benchmark and how many should be run? Should we have multiple metrics? If so, how would they be weighted in order to rank the systems? Or should they be condensed into a single score? What should be measured? Just the computer? The entire data center?

Update:
Fist fights
At the Green 500 BoF, a fist fight almost broke out (not really, but the discussion got very "lively") between someone that advocated using single precision math for the early part of a computation, then switching to double precision to converge to the final solution, and someone that thought this was gaming the system. This idea is "green" because many processors have much better single precision performance than double precision - over 10x better on a cell, 4x better on a GPGPU, probably even 2x on a x86. This lets more work get done with fewer processors or in less time, consuming less power. Should "green algorithms" be allowed, or even encouraged for the benchmark?

There was also discussion of creating various classes of systems, either by price or performance. One problem is that a megaflops per watt ranking favors small systems.

Gregg (who tagged along to steal power) posted his thoughts over at his blog. He tried to think of it from a CIO type perspective.