A compiler-guided approach for reducing disk power consumption by exploiting disk access locality

Power consumption of large servers and clusters has recently been a popular research topic, since this issue is important from both technical and environmental viewpoints. The prior research proposed disk power management as one of the important ways of reducing overall power of a large system and considered both hardware-based and softwareguided disk power reduction schemes. One of the common characteristics of the previously proposed approaches to disk power reduction is that they work with a given disk access pattern. In comparison, the goal of the approach proposed in this paper is to restructure application code using an optimizing compiler so that disk idle periods are lengthened. This in turn allows the underlying disk power management scheme to be more effective since such schemes usually prefer the long idle periods over the short ones. Our approach targets at large scientific applications that operate on disk-resident arrays using nested loops and exhibit regular data access patterns. To test the effectiveness of the proposed approach, we implemented it within an optimizing compiler and performed experiments with six data-intensive applications that manipulate disk-resident data. Our experimental analysis shows that the proposed approach is very successful in practice and reduces the total disk energy consumption on average by 18.17%, as compared to an execution without any disk power management, and by 11.55%, as compared to an execution that employs disks with low-power capabilities without our code restructuring approach.