Capacity Sharing and Stealing in Server-based Real-Time Systems
Ref: HURRAY-TR-051205 Publication Date: 1, Dec, 2005
Capacity Sharing and Stealing in Server-based Real-Time SystemsRef: HURRAY-TR-051205 Publication Date: 1, Dec, 2005
In this paper we introduce an algorithm that supports the coexistence of guaranteed and best-effort bandwidth servers in a dynamic scheduling environment. In addition to being able to efficiently reclaim residual capacities, originated by early completions, an overloaded active server can also steal future capacities of inactive best-effort servers. The proposed dynamic budget accounting mechanism ensures that at a particular time, the currently executing server is using a residual capacity, its own capacity or is stealing some future capacity, eliminating the need of additional server states or unbounded queues. The server to which the budget accounting is going to be performed is dynamically determined at the time instant when a capacity is needed. The paper describes and evaluates the proposed scheduling algorithm, stating that it can efficiently reduce the mean tardiness of periodic jobs. The achieved results become even more significant when tasks’ computation times have a large variance.