Container-Based Real-Time Scheduling in the Linux Kernel

In recent years, there has been a growing interest in supporting component-based software development of complex real-time embedded systems. Techniques such as machine virtualisation have emerged as interesting mechanisms to enhance the security of these platforms, while real-time scheduling techniques have been proposed to guarantee temporal isolation of different virtualised components sharing the same physical resources. This combination also highlighted criticalities due to overheads introduced by hypervisors, particularly for low-end embedded devices. This led to the need of investigating deeper into solutions based on lightweight virtualisation alternatives, such as containers. In this context, this paper proposes to use a real-time deadline-based scheduling policy built into the Linux kernel to provide temporal scheduling guarantees to different co-located containers. The proposed solution extends the SCHED_DEADLINE scheduling policy to schedule Linux control groups, allowing user threads to be scheduled with fixed priorities inside the control group scheduled by SCHED_DEADLINE. The proposed mechanism can be configured via control groups, and it is compatible with commonly used tools such as LXC, Docker and similar. This solution is compatible with existing hierarchical real-time scheduling analysis, and some experiments demonstrate consistency between theory and practice.