Generalized ERSS tree model: Revisiting working sets

Accurately characterizing the resource usage of an application at various levels in the memory hierarchy has been a long-standing research problem. Existing characterization studies are either motivated by specific allocation problems (e.g., memory page allocation) or they characterize a specific memory resource (e.g., L2 cache). The studies thus far have also implicitly assumed that there is no contention for the resource under consideration. The inevitable future of virtualization driven consolidation necessitates the sharing of physical resources at all levels of the memory hierarchy by multiple virtual machines (VMs). Given the lack of resource isolation mechanisms at several levels of the memory hierarchy within current commodity systems, provisioning resources for a virtualized application not only requires a precise characterization of its resource usage but must also account for the impact of resource contention due to other co-located applications during its lifetime. In this paper, we present a unifying Generalized ERSS Tree Model that characterizes the resource usage at all levels of the memory hierarchy during the entire lifetime of an application. Our model characterizes capacity requirements, the rate of use, and the impact of resource contention, at each level of memory. We present a methodology to build the model and demonstrate how it can be used for the accurate provisioning of the memory hierarchy in a consolidated environment. Empirical results suggest that the Generalized ERSS Tree Model is effective at characterizing applications with a wide variety of resource usage behaviors.