ABSTRACT
On-chip photonics is a disruptive technology that can offer substantial gains in terms of performance and power efficiency in large server processors. However, before this technology becomes commonplace, it is necessary to fix one of its most important problems, namely static power dissipation. Unlike electrical networks, optical networks are naturally constrained by their basic physics, which entails lasers to be continuously on while transmitting messages. Given that it is not possible to store photons, a logical zero or one is deduced based on the presence or absence of laser light. This leads to a significant amount of power dissipation because many a time, lasers are on, even though there is no network activity. Hence, there is a need to accurately predict network activity and modulate lasers accordingly. Over the past few years, a lot of work has been done in this space. In this chapter, some of the important contributions in this area are presented with respect to CPUs, manycore processors, multi-socket servers, and GPUs.
