Analyzing and Improving MPI Communication Performance in Overcommitted Virtualized Systems

Nowadays, it is an important trend in the system domain to use the software-based virtualization technology to build the execution environments (e.g., Clouds) and serve high performance computing (HPC) applications. However, with the extra virtualization layer, the application performance may be negatively affected. Studies revealed that the communication performance of the MPI library, which is widely used by the HPC applications, would suffer a high penalty when a physical host machine becomes overcommitted by virtual processors (VCPU). Unfortunately, the problem has not received enough attention and has not been solved yet in literature. In this paper, we investigate the reasons behind the performance penalty, and propose a solution to improve the communication performance of running MPI applications in the overcommitted virtualized systems. The experimental results show that by our proposal, most HPC applications can gain performance improvement to different extents among the overcommitted systems, depending on their communication patterns and the over committing level.