Performance Modeling and Analysis of P4 Programmable Devices With General Service Times

In our digitized society, emerging applications require highly-performing and flexible networks that can adapt to satisfy varying connectivity needs. P4 as a domain-specific programming language for data plane pipelines introduces the required flexibility through easy-to-use programmability. However, the performance of P4-capable devices is still an open question that has not yet been completely addressed. Understanding whether a P4-enabled device can meet the performance requirements for a specific network function pipeline is key for planning as well as for the selection of the proper deployment scenarios in a network. To bridge this gap, we propose a simple analytical model that can predict the performance of network functions written in P4 for a given device. The programmable data plane of P4 devices is modeled as a forward queueing system with a variable service rate that depends on the complexity of the configured data path program. On top of the data plane model, the controller's interaction is modeled as a feedback queueing system. In terms of the analysis, we first assume exponentially distributed service times in the data plane and control plane. In a second step, we extend the analysis to generally distributed service times using approximations. In order to cover a wide rang of possible behavior of the control plane, three types of distributions with different coefficients of variation are inspected: Erlang, exponential, and hyperexponential. We evaluate the accuracy of our model for different scenarios and show that the discrepancy between actual results and our analytical predictions does not exceed 8.7%. We also validate the model with a commercial P4 hardware switch.