HEELS: A Host-Enabled eBPF-Based Load Balancing Scheme

Abstract

Layer 4 (L4) load balancing is crucial in cloud computing and elastic microservices. Existing L4 load balancer designs can be split into two main categories: centralized designs using a hardware or software middlebox, and decentralized designs in which every node can play the role of the load balancer. Centralized designs offer better scheduling policies and easier worker node management, but suffer from I/O and CPU limitations. Decentralized designs scale better, but are harder to manage. We introduce HEELS, a novel load balancing scheme designed for internal cloud workloads and microservices, achieving the best of both worlds. HEELS uses the load balancer only during the connection establishment and allows clients and servers to communicate directly after that. Supporting general L4 load balancers and requiring no kernel changes, HEELS is readily deployable on the public cloud. We implement HEELS as a set of eBPF programs split across the client and server. Our evaluation shows that HEELS introduces minimal overheads, works with off-the-shelf load balancers (e.g., Katran by Meta), and significantly reduces the costs of cloud load balancers.