Period assignment in real-time scheduling of multiple virtual machines
Christine Niyizamwiyitira, Lars Lundberg · 2015
There are two levels of scheduling in real-time applications executing in a virtualized environment: traditional real-time scheduling of the tasks in the real-time application inside a Virtual Machine (VM), and scheduling of different VMs on the hypervisor level. In order to save more resources, we propose to schedule VMs that contains hard real-time application in an optimistic manner by considering VMs as a whole instead of being isolated. Based on the properties of the real-time applications inside the VMs, we obtain (worst-case) execution times and periods for the VMs containing the real-time applications. A VM's period will be chosen according to the requirement of the application that runs inside that VM. Through simulation, we investigate the impact of the length of different VMs' periods whether the VM context switching overhead is present or not. The tradeoff between resources consumption and period's length is presented. The results show that longer periods are better at handling higher overhead even with higher number of VMs that share the same hardware.