ECE555 Topic Presentation Energy-efficient real-time scheduling Xing Fu 20 September 2008 Acknowledge Dr. Jian-Jia Chen from ETH providing PPT Slides for IEEE RTAS 2007. Outline of Presentation. System-level Energy Management for Periodic Real-Time Tasks
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Energy-efficient real-time scheduling
20 September 2008
Acknowledge Dr. Jian-Jia Chen from ETH providing PPT Slides for IEEE RTAS 2007
Paper 1: Systematic results. Other related papers can be treated as special cases.
Paper 2: A closely related field: temperature efficient real time scheduling.
1. Main concepts
2. Key ideas
3. Introduction of underlying mathematics if time allowed
Guarantee Real Time
speed of all tasks will be
In practice, many task instances (Jobs) complete without presenting their worst-case workload.
The reduction of power is also needed to cut the power bill off
1. Heat is lost via conduction
2. Ambient temperature of the environment is constant.
CHIP Periodic Real-Time Tasks
Generate a feasible schedule SC for a set of tasks T such that Ψ(SC) is minimized.
This is an e-approximation algorithm which means the maximum temperature of the suboptimal scheme is at most e times as any optimal scheme.
is denoted by σi,j
Execute at two consecutive speeds of effective speed sT*so that the utilization is 100% is optimal
Execute at two consecutive speeds of effective speed sT*so that the utilization is 100% and frequently change speeds
speed Periodic Real-Time Tasks
UTAS: σi,j is negligible
Speed transition overhead
When α = 1, β = 0.01, and σi,j = 1 for any 0 < i j ≤ H
M = 3
Algorithm LTF is a 1.13-approximation algorithm
for energy efficiency.
Jian-Jia Chen, Heng-Ruey Hsu, Kai-Hsiang Chuang, Chia-Lin Yang, Ai-Chun Pang, and Tei-Wei Kuo, "Multiprocessor Energy-Efficient Scheduling with Task Migration Considerations", in ECRTS 2004.
Jian-Jia Chen, Heng-Ruey Hsu, and Tei-Wei Kuo, "Leakage-Aware Energy-Efficient Scheduling of Real-Time Tasks in Multiprocessor Systems", in RTAS 2006.
Applying Algorithm LTF for scheduling
 Dynamic and Aggressive Power-Aware Scheduling Techniques for Real-Time Systems
Example, Linear Matrix Inequality.
Examples: Thermal, fault tolerance, through-output.