Smart grid endpoints need to use two environments within a processing system (PS), one with a Linux-type operating system (OS) using the Arm Cortex-A53 cores for management tasks, and the other with a standalone execution or a real-time OS using the Arm Cortex-R5 cores. The Xen hypervisor and the OpenAMP framework allow this, but they may introduce a delay in the system, and some messages in the smart grid need a latency lower than 3 ms. In this paper, the Linux thread latencies are characterized by the Cyclictest tool. It is shown that when Xen hypervisor is used, this scenario is not suitable for the smart grid as it does not meet the 3 ms timing constraint. Then, standalone execution as the real-time part is evaluated, measuring the delay to handle an interrupt created in programmable logic (PL). The standalone application was run in A53 and R5 cores, with Xen hypervisor and OpenAMP framework. These scenarios all met the 3 ms constraint. The main contribution of the present work is the detailed characterization of each real-time execution, in order to facilitate selecting the most suitable one for each application.

Modern multiprocessing embedded applications require, in many cases, two different environments on the same platform: one that meets real-time requirements and another one with a general purpose operating system. Although several technologies can be used, two of the most popular are virtualization based on hypervisors and asymmetric multiprocessing software. However, using these tools introduces latency, which must be measured to verify compliance with real-time requirements. With the aim of facilitating these measurements, this work provides a hardware tool that is more precise and easier to use than other existing software solutions. The paper also studies the interrupt latency generated by different hypervisors and asymmetric multiprocessing frameworks in a Zynq UltraScale+ platform. This research work facilitates the accurate study of the temporal response of multiprocessor embedded systems, which allows for evaluating their suitability for applications with real-time requirements.