The SC08 Green500 BoF was led by Wu Feng from Virginia Tech. He started with a brief history for perspective. He then launched into the issues surrounding the creation of the list, a discussion of which is the purpose of the BoF. There were brief presentations from several vendors, folks from analyst IDC and journal HPCWire, and a couple of users.
I hadn't really intended to go to this session but tagged along with Glen (ironically because I needed to find power for my laptop). I tried to listen to the conversation, which got pretty energetic at times, from the perspective of a CIO/decision maker, and what they would want from the Green500. Here are my thoughts:
- A single, simple number will be hard to deliver. There is simply too great a range of uses for HPC, both in terms of size and computational problem, to have a single number mean much of anything. CIOs want a single number, but will also understand the complexity of the situation, and might even be skeptical of a single number as overly simplified. Several in the audience suggested creating segments or classes - I think this is appropriate, probably based on the size of the system in Tflops.
- The number should not have anything to do with cost or "value". While the vendors may want that, the Green500 should not evalutate value - let IDC, HPCwire, and ultimately the buyers do that.
- The major challenge is sorting out what is part of the data center facility and what is part of the system. I don't see an easy answer here. With the CIO hat on, I would say leave the facility out of it, as that's a separate issue with separate challenges and opportunities (ie tax incentives for green buildings, etc). Just tell me how much electricity the system takes, and how much heat it rejects. If you want to try to improve your score by taking on some of the facility issues, I'm guess I'm okay with that as I expect you will be able to improve your score, but at a greater cost (which again I will evaluate on my own).
- No CIO will make the decision to spend 5-8 figures on a Green500 ranking alone. They will ask their people, what can the system do, and what will it cost to acquire and operate it? The main gold of the Green500 should be to help vendors and IT staff have a conversation about energy efficiency. It should also help provide credibility to the final purchasing recommendation that the CIO sees. The CIO should be ensuring that the system meets the compute needs of the organization in a cost-effective and environmentally responsible way.