MegaProto: A Low-Power and Compact Cluster for High-Performance Computing Hiroshi Nakashima Hiroshi Nakamura † Mitsuhisa Sato ‡ Taisuke Boku‡

“MegaProto ” is a proof-of-concept prototype for our project “Mega-Scale Computing Based on Low-Power Technology and Workload Modeling”, implementing our key idea that a million-scale parallel system should be built with densely mounted low-power commodity processors. It also serves as a platform to implement and evaluate our new technologies such as power conscious compilation, highly reliable and high performance networking, highly depend-able cluster management, and multi-level scalable paral-lel programming. The building block of the MegaProto is a 1U-high 19 inch-rack mountable motherboard unit on which 16 low-power, one-dollar note-sized, commodity PC-architecture daughterboards are mounted with a high band-width, 2 Gbps per processor network based on Gigabit Eth-ernet. The peak performance of each unit is 14.4 GFlops for the first version and will improve to 38.4 GFlops in the sec-ond version through a processor/daughterboard upgrade. The intra- and inter-unit network bandwidths are 32 Gbps and 16 Gbps respectively. As for power consumption, the entire unit idles at less than 150 W and consumes 300-330 W maximum under extreme computational stress; this is comparable to or better than conventional 1U servers comprised of dual high-performance, power hungry pro-cessors, while benchmarks exhibit up to 279 % superior performance for some NPB programs. This demonstrates that higher performance can be achieved with low-power, densely populated architectures with commodity compo-nents