SLA-Aware Dynamic CPU Scaling in Business Cloud Computing Environments

Modern cloud computing platforms (e.g. Linux on Intel CPUs) feature ACPI-based (Advanced Configuration and Power Interface) mechanism, which dynamically scales CPU frequencies/voltages to adjust the CPU frequencies based on the workload intensity. With this feature, CPU frequency is reduced when the workload is relatively light in order to save energy, while increased when the workload intensity is relatively high. In business cloud computing environments, software products/services often need to "scale out"\´ to multiple machines to form a cluster to achieve a pre-defined aggregated performance goal (e.g., SLA-devised throughput). To reduce business operation cost, minimizing the provisioned cluster size is critical. However, as we show in this work, the working of ACPI in today\´s modern OS may result in more machines being provisioned, hence higher business operation cost, To deal with this problem, we propose a SLA-aware CPU scaling algorithm based on business SLA (Service Level Agreement aware). The proposed design rational and algorithm are a fundamental rethinking of how ACPI mechanisms should be implemented in business cloud computing environments. Contrary to the current forms of ACPI which simply adapt CPU power levels only based on workload intensity, the proposed SLA-aware algorithm is primarily based on current application performance relative to the pre-defined SLA. Specifically, the algorithm targets at achieving the pre-defined SLA as the top-level goal, while saving energy as the second-level goal.