Towards Diagnosing Accurately the Performance Bottleneck of Software-Based Network Function Implementation

The software-based Network Functions (NFs) improve the flexibility of network services. Comparing with hardware, NFs have specific behavioral characteristics. Performance diagnosis is the first and most difficult step during NFs' performance optimization. Does the existing instrumentation-based and sampling-based performance diagnosis methods work well in NFs' scenario? In this paper, we first re-think the challenges of NF performance diagnosis and correspondingly propose three requirements: fine granularity, flexibility and perturbation-free. We investigate existing methods and find that none of them can simultaneously meet these requirements. We innovatively propose a quantitative indicator, Coefficient of Interference (CoI). CoI is the fluctuation between per-packet latency measurements with and without performance diagnosis. CoI can represent the performance perturbation degree caused by diagnosis process. We measure the CoI of typical performance diagnosis tools with different types of NFs and find that the perturbation caused by instrumentation-based diagnosis solution is 7.39% to 74.31% of that by sampling-based solutions. On these basis, we propose a hybrid NF performance diagnosis, to trace the performance bottleneck of NF accurately.