Near-Storage Processing in FaaS Environments with Funclets

Serverless computing has disrupted how computation is performed in the Cloud. The ability to write Functions, and not care about infrastructure brings many benefits, including significantly lower deployment costs, improved developer workflow, scalability, resilience, and resource utilization. However, being stateless and not tied to specific machines, Functions need to access Cloud storage services to access data, which may require crossing the entire data center network incurring high overheads. Existing solutions either provide database APIs running on the storage servers to perform the data-intensive operations locally, or deploy entire Functions on storage servers. The former approach can not perform arbitrary computations locally on storage servers. The latter violates the principle of compute-storage disaggregation, resulting in poor scaling. We observe that allowing on-the-fly migration of I/O-intensive parts of Functions to storage nodes achieves both objectives. We propose a FaaS runtime that runs on both the compute servers and the servers running the storage services which introduces an efficient migration mechanism for Functions across machines to move I/O-intensive parts of Functions to the relevant storage node, with minimal code changes. This allows Functions to perform arbitrary computations on storage nodes, benefiting from the locality of data, without sacrificing the scalability offered by compute-storage disaggregation. We implement our approach in a state-of-the-art FaaS runtime and show that it improves latency and throughput in bandwidth-constrained FaaS workloads while making better utilization of idle CPU cycles on storage servers.