While attending a Hot Interconnects talk on supercomputing, I got the following idea. The TOP500 site provides graphs of the number of systems and total performance per interconnect family, which shows an approximate measure of the popularity of the different interconnects. But how do they affect the performance of an individual system? Clearly, a high-performance interconnect should result in higher efficiency than a commodity one. But by how much? And which systems would use what type of interconnect?