An Emulator for Evaluating Resource Allocation and Performance in Clouds

Efficient utilization of physical hosts in a private cloud depends on the configuration of the virtual machines (VMs), which must precisely comply with application requirements to avoid resource wastage. To achieve this, it is necessary to build knowledge about the performance of each physical host according to the number and type of VMs to be hosted to fulfil application demands. However, such a mapping would need the deployment and testing of each application that could be hosted in the cloud, which can be impracticable. To help this mapping of resources versus applications, we present the Cloud Workflow Emulator (CWE), a tool that allows to emulate the behavior of workflows and applications in virtualized environments. Through CWE, it is possible to evaluate machines performance when hosting VMs, enabling their classification according to the desired performance metrics in order to ensure the machine will comply with the necessary application requirements. Moreover, the evaluation using the emulator can help in the development of more efficient VM allocation strategies and algorithms. To demonstrate the CWE usefulness, we show an evaluation and classification of our test bed machines through the emulation of an image processing application and discuss how this classification improves the scheduling in the test bed´s hosts.