Technical Report Number
An increasing number of distributed real-time systems face the critical challenge of provid-ing quality of service guarantees in open and unpredictable environments. In particular, such systems often need to enforce utilization bounds on multiple processors in order to avoid over-load and meet end-to-end deadlines even when task execution times are unpredictable. While recent feedback control real-time scheduling algorithms have shown promise, they cannot han-dle the common end-to-end task model where each task is comprised of a chain of subtasks dis-tributed on multiple processors. This paper presents the End-to-end Utilization CONtrol (EU-CON) algorithm that adaptively maintains desired CPU utilization through performance feed-backs loops. EUCON is based on a model predictive control approach that models utilization control on a distributed platform as a multi-variable constrained optimization problem. A multi-input-multi-output model predictive controller is designed based on a difference equation model that describes the dynamic behavior of distributed real-time systems. Both control theo-retic analysis and simulations demonstrate that EUCON can provide robust utilization guaran-tees when task execution times deviate from estimation or vary significantly at run-time.
Lu, Chenyang; Wang, Xiaorui; and Koutsoukos, Xenofon, "Feedback Utilization Control in Distributed Real-Time Systems with End-to-End Tasks" Report Number: WUCSE-2004-31 (2004). All Computer Science and Engineering Research.