Kyoto University

This paper reports our 3.75-year empirical study on power-aware operations of Kyoto University’s supercom-puter system. The supercomputer system of 10 TFlops had required about 540 kW on average in its first fiscal year 2004. After that and one-year try-and-error of power ef-ficient operation, we implemented a simple but effective scheduler of jobs and machine powering to improve the per-load power efficiency by up to 39 % and to save 200 kW and $200,000 electric charge in the fiscal year 2006. The power-aware scheduler tries to minimize the number of ac-tive nodes in the system of eleven nodes keeping sufficient computational power for given loads. Thus the power-aware scheduler has not degraded, but has significantly improved, the service quality in terms of the average job-waiting time.