Scalable event system for mOS networking stack

Abstract

mOS is a specialized networking stack for developing stateful middleboxes. It allows the developers to focus on the core middlebox logic instead of re-implementing complex TCP flow management for each custom middlebox. mOS encourages modular programming of middleboxes by allowing to express custom middlebox operations with a set of event and event handlers. mOS event is defined as a notable condition that triggers middlebox-specific action, and is the key abstraction of mOS application. In this thesis, we focus on the performance scalability of the mOS event system where an application needs to handle several hundreds of thousands of concurrent flows with a dynamically changing event set. To achieve low memory usage and fast event registration at the same time, we design the mOS event system to easily share event metadata across multiple flows, and to allocate metadata IDs for efficient hash table lookup. We observe that the mOS’s event system outperforms the original design, and increases the overall event performance of mOS by up to almost twice, even when the system experiences frequent dynamic event registration with 192 K concurrent flows. The mOS event system delivers not only flexibility but also high performance, capable of handling a large number of concurrent flows.