Research And Optimization For High Performance I/O Virtualization Based On Paravirtual I/O

As one of the core components and infrastructure technologies of cloud computing,virtualization technology plays an indispensable role in cloud computing technology and services with its integrated redistribution capability.Meanwhile,the Virtual Symmetric Multiprocessing(VSMP)environment allows a virtual machine to possess multiple virtual CPUs.A hypervisor scheduler is responsible for providing a fair physical CPU time-sharing mechanism for multiple virtual CPUs,which can greatly improve the physical CPU resource utilization.As a result,VSMP has been widely deployed in enterprise-class applications in the current cloud computing infrastructure.This paper firstly introduces and expounds the main performance overhead of the current mainstream I/O virtualization solution-Paravirtual I/O solution under the VSMP environment.Then we demonstrates that the hardware-assisted approach and the interrupt remapping mechanism are the most direct,efficient and prevalent approach to remove the main performance bottlenecks in Paravirtual I/O solution.However,in this paper we originally identified a novel challenge called the “Interruptability Holder Preemption”(IHP)problem in the interrupt remapping mechanism.The IHP issue presents that a virtual CPU(vCPU)disabling the interruptability of guest's network device is de-scheduled by the hypervisor scheduler,which can easily invalidate the efficiency of the interrupt remapping mechanism.To solve this problem,we propose CoINT,a gasket coordinator residing in the hypervisor,to substantially enhance the network I/O performance.By empowering the hypervisor to be proactively aware of the interruptability information of the guest's network device,CoINT completely eliminates the “Interruptability Holder Preemption” problem and largely reduces I/O interrupt processing delay caused by hypervisor scheduler.We implement CoINT in KVM hypervisor and evaluate its efficiency and responsiveness using both macro and microlevel benchmarks.The results show that CoINT can improve the netperf throughput up to 3x compared with native KVM,and up to 1.3x compared with traditional interrupt remapping of hypervisor-level solution,in sacrifice of an negligible and reasonable overhead in the hypervisor.