vMPCP: A Synchronization Framework for Multi-Core Virtual Machines

The virtualization of real-time systems has received much attention for its many benefits, such as the consolidation of individually developed real-time applications while maintaining their implementations. However, the current state of the art still lacks properties required for resource sharing among real-time application tasks in a multi-core virtualization environment. In this paper, we propose vMPCP, a synchronization framework for the virtualization of multi-core real-time systems. vMPCP exposes the executions of critical sections of tasks in a guest virtual machine to the hypervisor. Using this approach, vMPCP reduces and bounds blocking time on accessing resources shared within and across virtual CPUs (VCPUs) assigned on different physical CPU cores. vMPCP supports periodic server and deferrable server policies for the VCPU budget replenish policy, with an optional budget overrun to reduce blocking times. We provide the VCPU and task schedulability analyses under vMPCP, with different VCPU budget supply policies, with and without overrun. Experimental results indicate that, under vMPCP, deferrable server outperforms periodic server when overrun is used, with as much as 80% more tasksets being schedulable. The case study using our hypervisor implementation shows that vMPCP yields significant benefits compared to a virtualization-unaware multicore synchronization protocol, with 29% shorter response time on average.