CMPSched$im: Evaluating OS/CMP interaction on shared cache management

CMPs have now become mainstream and are growing in complexity with more cores, several shared resources (cache, memory, etc) and the potential for additional heterogeneous elements. In order to manage these resources, it is becoming critical to optimize the interaction between the execution environment (operating systems, virtual machine monitors, etc) and the CMP platform. Performance analysis of such OS and CMP interactions is challenging because it requires long running full-system execution-driven simulations. In this paper, we explore an alternative approach (CMPSchedim) to evaluate the interaction of OS and CMP architectures. In particular, CMPSchedim is focused on evaluating techniques to address the shared cache management problem through better interaction between CMP hardware and operating system scheduling. CMPSchedim enables fast and flexible exploration of this interaction by combining the benefits of (a) binary instrumentation tools (Pin), (b) user-level scheduling tools (Linsched) and (c) simple core/cache simulators. In this paper, we describe CMPSchedim in detail and present case studies showing how CMPSchedim can be used to optimize OS scheduling by taking advantage of novel shared cache monitoring capabilities in the hardware. We also describe OS scheduling heuristics to improve overall system performance through resource monitoring and application classification to achieve near optimal scheduling that minimizes the effects of contention in the shared cache of a CMP platform.