The simulation and evaluation of dynamic voltage scaling algorithms
ISLPED '98 Proceedings of the 1998 international symposium on Low power electronics and design
Voltage scheduling problem for dynamically variable voltage processors
ISLPED '98 Proceedings of the 1998 international symposium on Low power electronics and design
Improving dynamic voltage scaling algorithms with PACE
Proceedings of the 2001 ACM SIGMETRICS international conference on Measurement and modeling of computer systems
Dynamic voltage scaling on a low-power microprocessor
Proceedings of the 7th annual international conference on Mobile computing and networking
Real-time dynamic voltage scaling for low-power embedded operating systems
SOSP '01 Proceedings of the eighteenth ACM symposium on Operating systems principles
EDF scheduling using two-mode voltage-clock-scaling for hard real-time systems
CASES '01 Proceedings of the 2001 international conference on Compilers, architecture, and synthesis for embedded systems
Intra-Task Voltage Scheduling for Low-Energy, Hard Real-Time Applications
IEEE Design & Test
Energy efficient CMOS microprocessor design
HICSS '95 Proceedings of the 28th Hawaii International Conference on System Sciences
Operating systems techniques for reducing processor energy consumption
Operating systems techniques for reducing processor energy consumption
Energy-efficient soft real-time CPU scheduling for mobile multimedia systems
SOSP '03 Proceedings of the nineteenth ACM symposium on Operating systems principles
Toward the placement of power management points in real-time applications
Compilers and operating systems for low power
Practical PACE for embedded systems
Proceedings of the 4th ACM international conference on Embedded software
Practical On-line DVS Scheduling for Fixed-Priority Real-Time Systems
RTAS '05 Proceedings of the 11th IEEE Real Time on Embedded Technology and Applications Symposium
Scheduling for reduced CPU energy
OSDI '94 Proceedings of the 1st USENIX conference on Operating Systems Design and Implementation
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Dynamic Voltage Scaling (DVS) is a promising method to achieve energy saving by slowing down the processor into multiple frequency levels in battery-operated embedded systems. However, the worst case execution time (WCET) of the tasks scheduled by DVS must be known ahead of time to ensure their schedulability. In reality, a system's workloads may change significantly without satisfying any prediction. In other words, a task's WCET may not provide useful information about its future real execution time (RET). This paper presents a novel Dynamic-Mode EDF scheduling algorithm when workloads change significantly. One of the Single-Mode, Dual-Mode, and Three-Mode frequency setting formats can be applied, based on the RET and the accumulated slack at run-time. Only one combination of the number of modes/speeds, speed-switching transition points, and the frequency scaling factor for each mode can lead to the best energy saving. Experimental results show that, given an RET pattern, our Dynamic-Mode DVS algorithm achieves an average 15% energy savings over the traditional two-mode DVS scheme on hard real-time systems. Additionally, we also consider speed-switching or energy transition overhead, and implement a preliminary test of our proposed algorithm. With a less aggressive voltage scaling strategy (fewer speed changes for each job), deadlines can still be strictly satisfied and an average of 14% energy consumption saving over a non-DVS scheme is observed.