ENSURE: Efficient Scheduling and Autonomous Resource Management in Serverless Environments

An imminent challenge in the serverless computing landscape is the escalating cost of infrastructure needed to handle the growing traffic at scale. This work presents ENSURE, a function-level scheduler and autonomous resource manager designed to minimize provider resource costs while meeting customer performance requirements. ENSURE works by classifying incoming function requests at runtime and carefully regulating the resource usage of colocated functions on each invoker. Beyond a single invoker, ENSURE elastically scales capacity, using concepts from operations research, in response to varying workload traffic to prevent cold starts. Finally, ENSURE schedules requests by concentrating load on an adequate number of invokers to encourage reuse of active hosts (thus further avoiding cold starts) and allow unneeded capacity to provably and gracefully time out. We implement ENSURE on Apache OpenWhisk and show that, across several serverless applications and compared to existing baselines, ENSURE significantly improves resource efficiency, by as much as 52%, while providing acceptable application latency.