| Title | Thermally Optimal Stop-Go Scheduling of Task Graphs with Real-Time Constraints |
| Author | *Pratyush Kumar, Lothar Thiele (ETH Zürich, Switzerland) |
| Page | pp. 123 - 128 |
| Keyword | Stop-go scheduling, Task-graphs, Real-time |
| Abstract | Dynamic thermal management (DTM) techniques to manage the load on a system to avoid thermal hazards are soon becoming mainstream in today’s systems. With the increas- ing percentage of leakage power, switching off the processors is becoming a viable alternative technique to speed scaling. For real-time applications, it is crucial that under such techniques the system still meets the performance constraints. In this pa- per we study stop-go scheduling to minimize peak temperature when scheduling an application, modeled as a task-graph, within a given makespan constraint. For a given static-ordering of exe- cution of the tasks, we derive the optimal schedule referred to as the JUST schedule. We prove that for periodic task-graphs, the optimal temperature is independent of the chosen static-ordering when following the proposed JUST schedule. Simulation experi- ments validate the theoretical results. |
| Slides |
| Title | Leakage Conscious DVS Scheduling for Peak Temperature Minimization |
| Author | Vivek Chaturvedi, *Gang Quan (Florida International University, U.S.A.) |
| Page | pp. 135 - 140 |
| Keyword | DVS, real-time scheduling, leakage-aware, thermal management, peak temperature |
| Abstract | In this paper, we incorporate the dependencies among
the leakage, the temperature and the supply voltage into the theoretical analysis and explore the fundamental characteristics on how to
employ dynamic voltage scaling (DVS) to reduce the peak operating
temperature. We find that, for a specific interval, a real-time scheduleusing the lowest constant speed is not necessarily the optimal
choice any more in minimizing the peak temperature. We identify
the scenarios when a schedule using two different speeds can outperform the one using the constant speed. In addition, we find that the constant speed schedule is still the optimal one to minimize the peak temperature at the temperature stable status when scheduling a periodic task set. We formulate our conclusions into several theorems with formal proofs. |
| Slides |
| Title | Reconfiguration-aware Real-Time Scheduling under QoS Constraint |
| Author | Hessam Kooti, *Deepak Mishra, Eli Bozorgzadeh (University of California, Irvine, U.S.A.) |
| Page | pp. 141 - 146 |
| Keyword | Quality of Service, Real-Time, Reconfiguration overhead |
| 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. |