Real-time performance measurements using UDP on Windows and Linux

The move towards Ethernet based communication solutions in automation is accompanied by a need for determinism and real-time performance. The subject of this paper is the measured real-time performance across a switched Ethernet segment. Performance at 100 Mbps and 1 Gbps network speed was measured using UDP on Windows and Linux. Output stack times in the 8-16 mus range were measured with low processor load. The real-time performance decreased significantly at high processor load. Measurements of performance across the network showed that 96-98% of the time was spent in the nodes at 1 Gbps network speed. At 100 Mbps 79-87% of the time was spent in the nodes. This paper concludes that the real-time Ethernet performance is determined mostly by the end node performance