Sloth: A Kernel-Bypass Scheduler Maximizing Energy Efficiency under Latency Constraints

In recent years, multi-hundred-gigabit networking applications such as Virtual Network Function (VNF) and Key Value Store (KVS) implementations have relied on kernel-bypass and polling to achieve maximum throughput. However, this performance improvement comes at the expense of high CPU usage and power consumption. This paper first analyses the trade-off between the power consumption, the latency and the throughput of VNF applications. We then present Sloth, an energy-aware scheduler that adapts the number of cores used by an application and their frequency. Sloth uses the information gathered in a training phase to maximize the energy reduction in real time while maintaining a user-provided service-level objective. Sloth manages to reduce CPU power consumption by up to 50% compared to the classical DPDK polling approach with only a 30 μs latency increase. Sloth also saves up to milliseconds of latency compared to state-of-the-art solutions at equivalent power consumption