In order to meet the requirements of both low power consumption and high performance in embedded server systems, a single IP address cluster of low power embedded CPUs can be built, based on the following policy: the number of CPUs increases when high performance services are required, while the number of CPUs decreases when there are few requests. A cluster of embedded SH7780 CPUs, called the SH Cluster, and an ordinary x86 server are evaluated using the httperf benchmark to demonstrate this idea. The result shows that the SH cluster reduces about 72.4% of the power consumption compared to that of the x86 server when handling 700 HTTP requests/sec, while each request takes 6.4 times longer than requests on the x86 server. The results also imply that if the required request rate is lower than 2500 ～ 3250 requests/sec, the SH Cluster is more energy-efficient than the x86 server, under the assumption that the SH Cluster scales well.
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