Open Letter to HPC Stakeholders

February 5, 2008

Dear High-Performance Computing Stakeholder,

We were extremely pleased with the outcome of the inaugural Green500 list. In our opinion, the Green500 had the desired effect of elevating the discussion of energy efficiency in the high-performance computing (HPC) community. We are indebted to the participants who submitted their power data from all over the world to ensure that their systems were accurately represented in the November 2007 Green500. We look forward to updating the Green500 periodically to ensure the list itself will reflect the current state of the art in energy-efficient, high-performance system designs.

Any list of this type is prone to controversy and criticism and the Green500 is no exception. We truly appreciate both the accolades that we have received and the suggestions for improvement. That being said, we have several priorities for the Green500 in the coming year.

First and foremost, we intend to work diligently to fully populate the list with actual measurements. Currently, systems that did not report measured power under load are listed using peak power. It is likely that the numbers used for these systems overestimate the actual power consumption. To increase the usefulness of the Green500 and to ensure fair comparisons for all systems, we will offer a second opportunity for those currently listed in the Green500 to submit actual power measurements under load for an updated list in late February 2008. We stress that we will not accept any changes in performance numbers or system configurations from the November 2007 Green500 list. Only measured power under load for current entries that abide by the Green500 run rules will be accepted.

Second, we are constantly trying to improve our run rules and measurement methodology. While the run rules will remain the same for the February 2008 Green500 list, please rest assured that over the next 12-18 months we will be conducting significant testing and software development to further automate the process of data collection and verification. Our goals are to ensure accuracy and fairness, make the process easier for participants, and reduce turnaround time for updating the list.

Third, we plan to broaden the opportunities for participation in the Green500. We will accomplish this through a number of initiatives that will take place various times throughout the year. Of course, we will have list updates in February 2008 as noted, then again in June 2008, following the launch of the June 2008 Top500. Additionally, we are planning an open forum at SC08 in November 2008 in Austin, Texas in a format to be determined.

In closing, we would again like to thank those that participated in the Green500 from submitters to critics since we believe that the participation and passion of the HPC community for energy efficiency is now self-evident. Please keep your comments and suggestions for improvement coming via .

We look forward to an exciting year for the Green500.

Wu Feng and Kirk W. Cameron
The Green500 List