Long Idle: Making Idle Networks Quiet for Platform Energy-Efficiency

Abstract

Today's platforms offer ubiquitous network connectivity through one or more communication interfaces and while the communication devices consume a small portion of the overall platform power the impact of network connectivity and individual packet processing on the overall platform energy consumption is significant, due to the non-deterministic characteristics of network traffic. In this paper, we show that significant energy is unnecessarily wasted at the platform level while it is idle and connected to one or more networks, especially unlicensed networks like WiFi or Ethernet, because the system is constantly processing what we term "background/noise" traffic. These are management, control or broadcast packets arriving at a rate high enough that prevents the system from taking full advantage of the platform-level power management states. We quantify the negative impact of network connectivity on platform energy-efficiency and provide novel techniques to mitigate this impact. We implemented these mitigation techniques in our wireless network interface cards and our results indicate that when our scheme is used the total platform sleep time increases by up to 40% with no performance degradation and no user experience impact.