Dynamic Memory Resource Management in Virtual Machines with Different Applications

Cloud computing by the use of virtual machines has become increasingly important in various situations. In such an environment, multiple virtual machines run on a single physical machine. Many hypervisor implementations have a ballooning function. This function enables virtual machine memory size to be dynamically changed at runtime. Hence, it is expected that dynamic memory resource management while considering the transition of application loads can improve its performance. In particular, I/O performance is expected to be improved significantly because it strongly depends on the size of the HDD cache in an operating system, e.g., a page cache in Linux. The Xen hypervisor has xenballoon, which dynamically changes the size of the virtual machine memory based on the size of memory consumed by the processes in the virtual machines and does not consider the size of the page cache. Thus, the I/O performance is not improved. In this paper, we propose a method for dynamic management of virtual machine memory size that takes into account the page cache hit ratio. We show the performance evaluation of the method for a read-only application, multiple read-only applications, and a read/write application. The experimental results demonstrate that our method can improve performance of I/O intensive applications in virtual machines.