[Article] Measuring and Reducing the Impact of the OS Kernel on End-to-End Latencies in Synchronous Packet Switched Networks

This paper presents an evaluation of the impact of the so-called OS latencies on the performance of a synchronous network based on global time coordination. The concept of end-to-end latency is first defined, by extending the concept of latency used to evaluate the performance of real-time systems, and the end-to-end latency provided by a general-purpose OS is measured as a benchmark. Finally, Real-Time techniques are used to reduce the worst case values of such a latency, showing how a gateway between synchronous and asynchronous networks can be implemented by using commercial-off-the-shelf hardware and a proper software stack (based on a Real-Time version of Linux). The use of a Real-Time OS is still a non-trivial task, which requires experience and the analysis of the specific application to devise the proper techniques to be applied. This work dissects the problem of OS-to-Network data transfer (and vice-versa) identifying the key sources of latencies and delay jitter, and solving each problem with the application of a proper technique.