| dc.description.abstract | Due to advancements in embedded hardware platforms, implementing subsystems of varying criticality levels on the same hardware platform is a trend for modern real-time systems. The Linux kernel is a common candidate for mixed-criticality designs due to its popularity, versatility, and open-source license. The Linux kernel has seen an increase in interest for real-time usage, and for several years, a patch commonly known as PREEMPT_RT has been developed to improve the kernel’s real-time capabilities. This thesis evaluates a Linux-based mixed-criticality system with the PREEMPT_RT patch. The focus is on the system’s ability to respond reliably to incoming messages and signals over GPIO, Ethernet, and PCIe in a distributed system. Dedicated measurement systems are designed to generate messages and signals over GPIO, Ethernet, and PCIe and measure the round-trip time.
The Linux kernel’s isolation mechanisms effectively lower the round-trip time for GPIO, Ethernet, and PCIe. They also increase the stability but do not provide total temporal isolation. Polling-based implementations are less affected by system load than interrupt-based implementations and produce reasonable results. The variance in the Linux kernel system latencies makes the kernel insufficient for hard real-time systems. Still, the proposed Linux-based mixed-criticality system design can be considered for soft real-time systems. | |
