Reconfiguration-aware real-time scheduling under QoS constraint

Abstract

Due to the increase in demand for reconfigurability in embedded systems, schedulability in real-time task scheduling is challenged by non-negligible reconfiguration overheads. Reconfiguration of the system during task execution affects both deadline miss rate and deadline miss distribution. On the other hand, Quality of Service (QoS) in several embedded applications is not only determined by deadline miss rate but also the distribution of the tasks missing their deadlines (known as weakly-hard real-time systems). As a result, we propose to model QoS constraints as a set of constraints on dropout patterns (due to reconfiguration overhead) and present a novel online solution for the problem of reconfiguration-aware real-time scheduling. According to QoS constraints, we divide the ready instances of the tasks into two groups: critical and non-critical, then model each group as a network flow problem and provide an online scheduler for each group. We deployed our method on synthetic benchmarks as well as software defined radio implementation of VoIP on reconfigurable systems. Results show that our solution reduces the number of QoS violations by 19.01 times and 2.33 times (57.02%) in comparison with Bi-Modal Scheduler (BMS) [1] for synthetic benchmarks with low and high QoS constraint, respectively.

Automating Elimination of Idle Functions by Runtime Reconfiguration

“…Reconfiguration overhead is one of the major issues that limit performance of reconfigurable designs. In Kooti et al [2011], the reconfiguration time is known before execution and used as a constant during scheduling. A partition approach is proposed in He et al [2012], where functions activated at different time intervals are combined into the same reconfigurable module.…”