Mediating Power Struggles on a Shared Server

Most of today's servers, with numerous CPU cores and other plentiful direct resources, host co-located workloads using mechanisms to reduce hardware resource contention. However, power is an equally important indirect resource in a server that is shared between the co-located applications, for which they can contend, especially when power budgets are tight. We refer to this as a "power struggle". While there is a considerable amount of prior effort on server power capping, they are largely oblivious to power as an indirectly shared resource. This indirect resource exhibits a unique set of properties - spatial non-multiplexing, non-convex, fluidic, time-shifting and dynamic capacity - which have not been explicitly tackled so far. We propose policies that explicitly consider these properties to mediate power struggles, implement these on real hardware, and provide experimental results to show the performance benefits of our solution.