NCA: Accelerating Network Caching with eXpress Data Path

In-memory network caching is a common solution to relieve pressure on databases and applications. However, the in-memory caching applications such as redis and memcached cannot achieve maximum performance due to the bottleneck inherent in the linux network stack. While most of the solutions today rely on kernel-bypass approaches or reengineering of applications, little attention has been given to in-kernel processing. In this article, we present NCA (Network Caching Accelerator), an in-kernel cache to release overhead brought by the linux network stack, enabling flexibility and customization without bypassing the kernel that was unthinkable before. NCA can process the cache requests as early as possible in the linux network, bringing significant performance gains without modifying the cache application itself. It works in concert with the linux kernel, enabling reuse of the security model of linux kernel. Additionally, NCA uses little CPU resources, leaving valuable CPU cycles for other applications and processes on the host. We evaluate NCA using redis as an example, and find that redis with NCA can achieve three times the throughput of the original redis. Besides, other caching applications can also use NCA to improve their performance.