Meeting Real-Time Requirements on Industrial IoT Devices

Connecting mission-critical real-time devices to IP networks adds a source of unpredictability to industrial systems, potentially making them unsafe. With our research, we detect, analyze, and mitigate network-generated interrupt floods from the perspective of embedded systems.

Motivation

Embedded systems have been used to control physical environments for decades. Usually, such use cases require low latencies between commands and actions as well as a high predictability of the expected worst-case delay. To achieve this on small, low-powered microcontrollers, Real-Time Operating Systems are used to manage the different tasks on these machines as deterministically as possible. However, with the advent of the Internet of Things (IoT) in industrial applications, the same embedded systems are now equipped with networking capabilities, possibly endangering critical real-time systems through an open gate to interrupts.

In our work, we analyze the impact network-generated interrupts have on embedded real-time systems. We furthermore develop approaches to mitigate real-time breaking effects of network processing on microcontrollers from inside the device.

Approaches

Among our approaches to solve the real-time issue are mitigation algorithms that detect network overloads and control the incoming packet flow from within the operating system. Since these only allow to react to high network loads and are not able to distinguish between different packet priorities, another approach is the adaptation of the network interface controller generating interrupts for incoming packets. By expanding its receive queue structure and making it adaptivley configurable, IP flows can be filtered and prioritized before notifications are sent to the real-time operating system. This way, critical tasks can be guaranteed to receive packets within their deadlines while unrelated packet loads can be preempted before generating any workload. The following figure shows an example design of such a network interface controller.

Publications

• Differentiating network flows for priority-aware scheduling of incoming packets in real-time iot systems. Christoph Blumschein, Ilja Behnke, Lauritz Thamsen, and Odej Kao. 25th International Symposium On Real-Time Distributed Computing (ISORC). IEEE. 2022. [arXiv preprint]
• A priority-aware multiqueue nic design for real-time iot devices. Ilja Behnke, Philipp Wiesner, Robert Danicki, and Lauritz Thamsen. In Proceedings of the 37th ACM/SIGAPP Symposium on Applied Computing. ACM. 2022. [arXiv preprint]
• Detecting and Mitigating Network Packet Overloads on Real-Time Devices in IoT Systems. Robert Danicki, Martin Haug, Ilja Behnke, Laurenz Mädje and Lauritz Thamsen. 4th International Workshop on Edge Systems, Analytics and Networking (EdgeSys’21). ACM. 2021. [arXiv preprint]
• PIERES: A Playground for Network Interrupt Experiments on Real-Time Embedded Systems in the IoT. Franz Bender, Jan Jonas Brune, Nick Lauritz Keutel, Ilja Behnke and Lauritz Thamsen. In the International Conference on Performance Engineering Companion (LTB ‘21). ACM/SPEC. 2021. [arXiv preprint]
• Interrupting Real-Time IoT Tasks: How Bad Can It Be to Connect Your Critical Embedded System to the Internet?. Ilja Behnke, Lukas Pirl, Lauritz Thamsen, Robert Danicki, Andreas Polze and Odej Kao. 39th International Performance Computing and Communications Conference (IPCCC’20). IEEE. 2020. [arXiv preprint] [video]

Contact

If you have any questions or are interested in collaborating with us on this topic, please get in touch with Ilja!