Capacity sharing and stealing in serverbased real-time systems

A dynamic scheduler that supports the coexistence of guaranteed and non-guaranteed bandwidth servers is proposed. Overloads are handled by an efficient reclaiming of residual capacities originated by early completions as well as by allowing reserved capacity stealing of non-guaranteed bandwidth 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 reserved 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. This paper describes and evaluates the proposed scheduling algorithm, showing 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

Static-Threshold-Limited on-Demand Guaranteed Service for Asynchronous Traffic in Timely-Token Protocol

In this paper, an improved Timely-Token protocol with enhanced best-effort service for improved capacity allocation to the asynchronous (that is, non real-time) traffic is proposed. Through analytical approach and the use of computer simulations, the improved Timely-Token protocol is compared with the existing Timely-Token protocol. In particular, if AT denotes a threshold value, then, when compared to the existing Timely-Token protocol, the improved protocol will allocate additional average of AT time units to the asynchronous traffic in every cycle