Towards Efficient Supercomputing: A Quest for the Right Metric.
Over the past decade, we have been building less and less efficient supercomputers, resulting in the construction of substantially larger machine rooms and even new build- ings. In addition, because of the thermal power envelope of these supercomputers, a small fortune must be spent to cool them. These infrastructure costs coupled with the ad- ditional costs of administering and maintaining such (un- reliable) supercomputers dramatically increases their to tal cost of ownership. As a result, there has been substantial in - terest in recent years to produce more reliable and more ef- ficient supercomputers that are easy to maintain and use. But how does one quantify efficient supercomputing? That is, what metric should be used to evaluate how efficiently a supercomputer delivers answers? We argue that existing efficiency metrics such as the performance-power ratio are insufficient and motivate the need for a new type of efficiency metric, one that incorpo- rates notions of reliability, availability, productivity , and to- tal cost of ownership (TCO), for instance. In doing so, how- ever, this paper raises more questions than it answers with respect to efficiency. And in the end, we still return to the performance-power ratio as an efficiency metric with re- spect to power and use it to evaluate a menagerie of pro- cessor platforms in order to provide a set of reference data points for the high-performance computing community.