Abstract: |
Traditionally hard real-time operating systems (RTOS) were reserved for applications with very restrictive requirements, such as aviation, industrial control or safety, where upper bounds of jitter and latency were guaranteed. However, requirements of Industry 4.0 and Industrial Edge Artificial Intelligence (AI) are different. Nowadays Industrial Edge AI does not control safety critical tasks, it analyses data and applies AI models to optimize industrial processes. Thus, they present soft real-time requirements: the sooner a result is returned the better, but no critical harm for operators or industrial assets is introduced by delays on the results from the AI services. Thus, Industrial Edge AI applications have been usually deployed as software containers or on general purpose Operating Sys-tems (OS). However, latest Linux kernel versions include a preemption option to transform general Linux distributions into soft RTOS. This paper focuses on the effect of this option for Industrial Edge AI. In order to measure its impact, three different experiments have been defined, where Raspberry Pis (RPis) and a PLC send data using MQTT and OPC UA Pub/Sub, under different sampling frequencies and computational load conditions. Then, Java and Python clients have been deployed on a different RPi running two versions of the Linux Kernel, the regular one and the soft real-time one. Finally, latency, jitter and packet loss measures have been taken in several variations of these setups in order to identify the response of each Linux Kernel for different use cases. Results of the experiments have been used to generate general guidelines for kernel selection for different use cases. |