System Virtualization in the Multi-core Era - a QoS Perspective

Emergence of multi-core servers and the need for green computing has necessitated the resurgence of system virtualization. System virtualization has re-emerged as an answer to many critical issues being faced by the enterprise computing infrastructure. The issues that virtualization addresses are myriad, with the most popular one being server consolidation. Server consolidation deals with the problem of co-hosting multiple, independent application servers on a single physical machine. Abundance of virtualization technologies for commodity systems has given the necessary impetus for adoption of virtualization based solutions, particularly in the enterprise segment. However, most of the emerging virtualization solutions still need to address several challenges. Most prominent of the challenges, that are being faced today, are for the I/O virtualization architectures. Current technologies fall short in addressing the performance and security issues for I/O workloads on virtualized servers. Virtualized servers allow for co-hosting multiple independent servers as virtual machines (VMs), on the same physical machine. Hence, on virtualized servers multiple VMs share some or all the physical resources. When compared to non-virtualized servers, virtualized servers show better utilization of system resources. In virtualization parlance, the number of independent servers, that can be hosted as VMs on a virtualized server, is called the consolidation ratio. The consolidation ratio depends on the machine’s capacity and the workload of the individual servers to be consolidated. Arriving at the consolidation ratio is a complex process. Majority of the capacity planning efforts have focused on the CPU component of the workload while consolidating workloads. This is effective for compute workloads. The consolidation ratio for such workloads can be arrived at by aggregating the CPU workload component of the