Abstract:

As one of the most important technology of cloud computing,virtual machine (VM) technology has attracted considerable attention in recent years.But the virtual machine monitor(VMM) impacts the performance of real-time applications and parallel applications due to semantic gap. In this paper we analyze the Credit scheduler of Xen VMM, propose a novel soft real-time scheduling algorithm based on the Credit, and implement a scheduler prototype base on the new algorithm, which can satisfy the requirements of the soft realtime VM scheduling. In this new scheduling algorithm the Credit is pre-allocated to the soft real-time VMs according to the occupation rate of the CPU, and the scheduler adopts the dynamic time slice scheduling mechanism and works in non-work-conserving mode to realize soft real-time scheduling so as to guarantee that the scheduling period meets the requirements.Distinguishing the parallel and the non-parallel VMs and using different strategies ensure the execution of realtime tasks as well as meet the requirement of resource utilization.Test results show that the new algorithm has good performance in scheduling both parallel and non-parallel soft real-time tasks and hence meets the requirements of soft real-time application scheduling.

Key words: soft real-time VM;scheduling algorithm;Xen;Credit pre-allocation1