QoS prediction for dynamic reconfiguration of component based software systems

• First mathematical model to predict QoS impacts of dynamic reconfiguration on running software systems.
• QoS impact formulation is based on abstract hardware and software conditions.
• QoS prediction fits for multi-core CPU and varying workload environments.
• A prediction case study of the QoS impacts of existing dynamic reconfiguration approaches.
• Verification of the prediction results by simulation of the same reconfiguration scenario on DynaQoS platform.

It is difficult to choose the appropriate reconfiguration approach to satisfy the quality of service (QoS) requirements of a software system if the properties of that approach are not known. This problem significantly restricts the application of dynamic reconfiguration approaches to mission-critical or non-stop systems, where QoS is a major performance indicator. This paper proposes a model to predict how the QoS of a running software system will be affected by dynamic reconfiguration and show how it out-performed the existing methods in this area in three aspects. First, unlike existing simulation based models, this prediction model was based on easily implemented mathematical functions. Second, compared with the time-consuming simulation approaches, QoS prediction using this model was achieved in a shorter timeframe. Third, unlike the existing approaches that are built on different platforms for individual scenarios, this model generalized QoS prediction onto a single virtual platform that was modeled by abstract hardware and software conditions. The proposed model has been verified by reconfiguration simulation to a reasonable level of accuracy and thus the viability and safety for the use of the model has been confirmed.