Two benchmarks provide a good starting point for energy-efficiency accounting in servers—the SPECpower_ssj2008 benchmark (available at http://www.spec.org/power_ssj2008/) and the JouleSort metric (available at http://sortbenchmark.org/ ).

a. Look up the descriptions of the two benchmarks. How are they similar? How are they different? What would you do to improve these benchmarks to better address the goal of improving WSC energy efficiency?

b. JouleSort measures the total system energy to perform an out-of-core sort and attempts to derive a metric that enables the comparison of systems ranging from embedded devices to supercomputers. Look up the description of the Joule Sort metric at http://sortbenchmark.org. Download a publicly available version of the sort algorithm and run it on different classes of machines—a laptop, a PC, a mobile phone, etc.—or with different configurations. What can you learn from the JouleSort ratings for different setups?

c. [Discussion] <6.2>Consider the system with the best JouleSort rating from your experiments above. How would you improve the energy efficiency? For example, try rewriting the sort code to improve the JouleSort rating. What does running sort in the cloud do to energy efficiency?