Rethinking Virtual Machine Interference in the Era of Cloud Applications

Data centers are increasingly employing virtualization as a means to ensure the performance isolation for latency-sensitive applications while allowing co-locations of multiple applications. Previous research has shown that virtualization could offer excellent resource isolation. However, whether virtualization can mitigate the interference among micro-architectural resources has not been well studied. This paper presents an in-depth analysis of the performance isolation effect of virtualization technology on various micro-architectural resources (i.e., L1 D-Cache, L2 Cache, last level cache (LLC), hardware prefetchers and Non-Uniform Memory Access) by mapping the CloudSuite benchmarks to different sockets, different cores of one chip, and different threads of one core. For each resource, we investigate the correlation between performance variations and contention by changing VM mapping policies according to different application characteristics. Our experiments show that virtualization has rather limited micro-architectural isolation effects. Specifically, LLC interference can degrade applications performance by as much as 28%. When it comes to intra-core resources, the applications performance degradation can be as much as 27%. Additionally, we outline several opportunities to improve performance by reducing misbehavior VM interference.