A Cooperative Predictive Control Approach to Improve the Reconfiguration Stability of Adaptive Distributed Parallel Applications

摘要

Adaptiveness in distributed parallel applications is a key feature to provide satisfactory performance results in the face of unexpected events such as workload variations and time-varying user requirements. The adaptation process is based on the ability to change specific characteristics of parallel components (e.g., their parallelism degree) and to guarantee that such modifications of the application configuration are effective and durable. Reconfigurations often incur a cost on the execution (a performance overhead and/or an economic cost). For this reason advanced adaptation strategies have become of paramount importance. Effective strategies must achieve properties like control optimality (making decisions that optimize the global application QoS), reconfiguration stability expressed in terms of the average time between consecutive reconfigurations of the same component, and optimizing the reconfiguration amplitude (number of allocated/deallocated resources). To control such parameters, in this article we propose a method based on a Cooperative Model-based Predictive Control approach in which application controllers cooperate to make optimal reconfigurations and taking account of the durability and amplitude of their control decisions. The effectiveness and the feasibility of the methodology is demonstrated through experiments performed in a simulation environment and by comparing it with other existing techniques.