Towards a Robust MMIO-based Synchronized Clock for Virtualized Edge Computing Devices
Jan Ruh · 2021
Mixed-criticality is a key characteristic of Fog Computing Platforms posing challenging requirements concerning workload isolation, resource utilization, orchestration, and timing behavior. Virtualization featuring a hypervisor that logically partitions physical resources of edge computing devices has been identified to support these stringent requirements. However, fulfilling conflicting requirements, such as deterministic timing behavior or workload isolation and resource utilization or orchestration, remains challenging. A common approach to this problem is the application of the time-triggered paradigm to task and network scheduling. A precondition of the time-triggered paradigm is a global time base provided by the execution of a clock synchronization algorithm. In previous work [1], we provided a comprehensive analysis of clock synchronization in virtualized distributed real-time systems using a formal model. We could show that a bounded sub-microsecond clock synchronization precision is feasible utilizing a type-1 hypervisor implementing the dependent clock paradigm. In the paper at hand, we introduce an MMIO-based synchronized clock that tackles drawbacks of previous implementations making for a more robust source of a global time base.