Triage

Abstract

The ease of deployment of battery-powered and mobile systems is pushing the network edge far from powered infrastructures. A primary challenge in building untethered systems is offering powerful aggregation points and gateways between heterogeneous end-points---a role traditionally played by powered servers. Microservers are battery-powered in-network nodes that play a number of roles: processing data fromclients, aggregating data, providing responses to queries, and actingas a network gateway. Providing QoS guarantees for theseservices can be extremely energy intensive. Since increasedenergy consumption translates to a shorter lifetime, there is a need for a new way to provide these QoS guarantees at minimal energy consumption.This paper presents Triage, a tiered hardware and softwarearchitecture for microservers. Triage extends the lifetime of a microserver by combining two independent, but connected platforms: a high-power platform that provides the capability to executecomplex tasks and a low-power platform that provides high responsiveness at low energy cost. The low-power platform acts similarto a medical triage unit, examining requests to find critical ones, and scheduling tasks to optimize the use of the high-powerplatform. The scheduling decision is based on evaluating each task's resource requirements using hardware-assisted profiling of execution time and energy usage. Using three microserver services, storage, network forwarding, and query processing, we show that Triage provides more than 300% increase in microserver lifetime over existing systems while providing probabilistic quality of service guarantees.