Software techniques to mitigate performance inconsistency by shared caches in virtualized environments

Abstract

Cloud computing is one of the most broadly used in computer science and industry today. The cloud computing typically use virtualization technology, and this technique allows servers and data storage to be shared and utilization be improved. It enables multiple guest virtual machines to efficiently share the same physical resources. Virtualization systems need to reduce some defect causing shared resources compared to conventional systems. Especially in a cloud computing environment coupled with billing policies, the important issue is to maintain each performance consistency for guest virtual machines rather than overall system throughput. There are many shared resources to determine the consistency in a physical machine. The shared cache contention on a hypervisor causes performance degradation to virtual machines and reduces system performance consistency. We will mainly discuss the shared last level cache (LLC), one of the traditional computer architecture and operating systems issues that has caused numerous of stall cycles when LLC misses occur. Furthermore, we will discuss improving the overall performance throughput as well as the performance consistency. To address these factors, we describe supposed mechanism called IoVT (Isolation of Virtual-machine Thrashing). The IoVT make separates the LLC into two zones, called isolation zone for thrashing virtual machines and conventional zone in order to maintain LRU based shared cache policy. By using this simple software technique, the conventional cache can reduce interference between guest virtual machines; IoVT was shown to significantly reduce the performance variation. In this paper, we explore the proposed mechanism with experiments on real virtualization systems. By applying IoVT, improve throughput improved by 5.57%, and performance consistency increased by 355%. The results show that our scheme, a simple software technique, can maintain the performance consistency for guest virtual machines compared...