Introducing TinyKVM for High-Performance CDN Edge Services

On the Internet today, Content Delivery Networks (CDNs) are widely used to increase performance and reduce latency, by spreading the workload over CDN Edge Servers that are located as close as possible to the users. Content is stored in HTTP caches at the edge servers, and requests might be load-balanced over several replicated edge servers in order to try to handle requests closer to users. In this way, bottlenecks are avoided and communication latency is reduced. The caches can often run on the bare metal to achieve native performance, or in Docker. However, there is also a trend towards sandboxing, due to the demand for customer separation (multi-tenancy) and for security reasons, even though sandboxing will often reduce performance and increase latencies. In order to address these two sets of conflicting goals, this paper presents a novel modern specialized VM, referred to as "TinyKVM", for the purposes of computation on CDN edge servers. It is designed for low overhead, minimal footprint and close-to-native compute performance. The paper demonstrates that HTTP caching - and other services - on Edge servers can provide sandboxing using hardware virtualization, without having to compromise much in terms of performance and overheads. This paper describes the architecture of "TinyKVM", as well as the usability and performance of the TinyKVM implementation, using well-known benchmarks to demonstrate that it has native performance with no overhead and very low fixed overheads.