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Measuring and reducing the impact of the operating system kernel on end-to-end latencies in synchronous packet switched networks


Luca Abeni, DISI, University of Trento, Via di Sommarive 14, Trento 38123, Italy.



This paper presents an evaluation of the impact of the so-called operating system (OS) latencies on the performance of a synchronous network based on global time coordination. The concept of end-to-end latency was 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 was measured as a benchmark. Finally, real-time techniques were 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 nontrivial 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. Copyright © 2011 John Wiley & Sons, Ltd.