Low latency network traffic processing with commodity hardware

Packet processing on commodity hardware is a cost-efficient and flexible alternative to specialized networking hardware. In case of Linux, the classical QoS mechanisms (e.g DiffServ) assume that the outgoing link is the bottleneck. However, on commodity hardware the CPU typically becomes the bottleneck in packet processing. Taking into account current trends in the Internet, we assume that the percentage of latency-sensitive applications (e.g. VoIP, video conferencing, online gaming) will increase. Thus, we propose to extend the Linux NAPI with respect to preferring latency-sensitive traffic at the ingress before reaching the CPU. In this paper, we investigate a new concept for the Linux NAPI for low latency packet processing. Based on a model of a Linux software router, we show in a case study that our concept strongly improves the packet latency of real-time packets at acceptable low costs regarding the achievable maximum throughput. Our model is calibrated and validated based on real testbed measurements (e.g. profiling).