Motivating future interconnects: a differential measurement analysis of PCI latency

Local interconnect architectures are at a cusp in which advances in throughput have come at the expense of power and latency. Moreover, physical limits imposed on dissipation and packaging mean that further advances will require a new approach to interconnect design. Although latency in networks has been the focus of the High-Performance Computing architect and of concern across the computer community, we illustrate how an evolution in the common PCI interconnect architecture has worsened latency by a factor of between 3 and 25 over earlier incarnations.