Poris: A Scheduler for Parallel Soft Real-Time Applications in Virtualized Environments
Song Wu, Like Zhou, Huahua Sun, Hai Jin, Xuanhua Shi · IEEE Transactions on Parallel and Distributed Systems · 2015
With the prevalence of cloud computing and virtualization, more and more cloud services including parallel soft real-time applications (PSRT applications) are running in virtualized data centers. However, current hypervisors do not provide adequate support for them because of soft real-time constraints and synchronization problems, which result in frequent deadline misses and serious performance degradation. CPU schedulers in underlying hypervisors are central to these issues. In this paper, we identify and analyze CPU scheduling problems in hypervisors. Then, we design and implement a parallel soft real-time scheduler according to the analysis, namedPoris, based on Xen. It addresses both soft real-time constraints and synchronization problems simultaneously. In our proposed method,priority promotionanddynamic time slicemechanisms are introduced to determine when to schedulevirtual CPUs(VCPUs) according to the characteristics of soft real-time applications. Besides, considering that PSRT applications may run in avirtual machine(VM) or multiple VMs, we presentparallel scheduling,group schedulingandcommunication-driven group schedulingto accelerate synchronizations of these applications and make sure that tasks are finished before their deadlines under different scenarios. Our evaluation showsPoriscan significantly improve the performance of PSRT applications no matter how they run in a VM or multiple VMs. For example, compared to the Credit scheduler,Porisdecreases the response time of web search benchmark by up to 91.6 percent.