License: 
Creative Commons Attribution 4.0 International license (CC BY 4.0)
When quoting this document, please refer to the following
DOI: 10.4230/LIPIcs.ECRTS.2023.6
URN: urn:nbn:de:0030-drops-180354
URL: http://dagstuhl.sunsite.rwth-aachen.de/volltexte/2023/18035/
Dengler, Eva ;
Raffeck, Phillip ;
Schuster, Simon ;
Wägemann, Peter
FusionClock: Energy-Optimal Clock-Tree Reconfigurations for Energy-Constrained Real-Time Systems
Abstract
Numerous embedded real-time systems have, besides their timing requirements, strict energy constraints that must be satisfied. Examples of this class of real-time systems are implantable medical devices, where knowledge of the worst-case execution time (WCET) has the same importance as of the worst-case energy consumption (WCEC) in order to provide runtime guarantees. The core hardware component of modern system-on-chip (SoC) platforms to configure the tradeoff between time and energy is the system’s clock tree, which provides the necessary clock source to all connected devices (i.e., memory, sensors, transceivers). Existing energy-aware scheduling approaches have shortcomings with regard to these modern, feature-rich clock trees: First, with their reactive, dynamic (re-)configuration of the clock tree, they are not able to provide static guarantees of the system’s resource consumption (i.e., energy and time). Second, they only account for dynamic voltage/frequency scaling of the CPU and thereby miss the reconfiguration of clock sources and clock speed for the other connected devices on such SoCs. Third, they neglect the reconfiguration penalties of frequency scaling and clock/power gating in the presence of the CPU’s sleep modes.
In this paper, we present FusionClock, an approach that exploits a fine-grained model of the system’s temporal and energetic behavior. By means of our developed clock-tree model, FusionClock processes time-triggered schedules and finally generates optimized code for a system where offline-determined and online-applied reconfigurations lead to the worst-case-optimal energy demand while still meeting given timing-related deadlines. For statically determining these energy-optimal reconfigurations on task level, FusionClock builds a mathematical optimization problem based on the tasks' specifications and the system’s resource-consumption model. Specific components like transceivers of SoCs usually have strict requirements regarding the used clock source (e.g., phase-locked loop, RC network, oscillator). FusionClock accounts for these clock-tree requirements with its ability to exploit application-specific knowledge within an optimization problem. With our resource-consumption model for a modern SoC platform and our open-source prototype of FusionClock, we are able to achieve significant energy savings while still providing guarantees for timeliness, as our evaluations on a real hardware platform (i.e., ESP32-C3) show.
BibTeX - Entry
@InProceedings{dengler_et_al:LIPIcs.ECRTS.2023.6,
author = {Dengler, Eva and Raffeck, Phillip and Schuster, Simon and W\"{a}gemann, Peter},
title = {{FusionClock: Energy-Optimal Clock-Tree Reconfigurations for Energy-Constrained Real-Time Systems}},
booktitle = {35th Euromicro Conference on Real-Time Systems (ECRTS 2023)},
pages = {6:1--6:23},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-280-8},
ISSN = {1868-8969},
year = {2023},
volume = {262},
editor = {Papadopoulos, Alessandro V.},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/opus/volltexte/2023/18035},
URN = {urn:nbn:de:0030-drops-180354},
doi = {10.4230/LIPIcs.ECRTS.2023.6},
annote = {Keywords: energy-aware scheduling, device-aware whole-system analysis, clock tree}
}
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Keywords: |
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energy-aware scheduling, device-aware whole-system analysis, clock tree |
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Collection: |
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35th Euromicro Conference on Real-Time Systems (ECRTS 2023) |
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Issue Date: |
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2023 |
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Date of publication: |
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03.07.2023 |
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Supplementary Material: |
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Software (ECRTS 2023 Artifact Evaluation approved artifact): https://doi.org/10.4230/DARTS.9.1.2
Software (Source Code): https://gitlab.cs.fau.de/fusionclock |
