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Documents authored by Dengler, Eva

Document
DOI: 10.4230/OASIcs.WCET.2024.2
The Platin Multi-Target Worst-Case Analysis Tool

Authors: Emad Jacob Maroun, Eva Dengler, Christian Dietrich, Stefan Hepp, Henriette Herzog, Benedikt Huber, Jens Knoop, Daniel Wiltsche-Prokesch, Peter Puschner, Phillip Raffeck, Martin Schoeberl, Simon Schuster, and Peter Wägemann

Published in: OASIcs, Volume 121, 22nd International Workshop on Worst-Case Execution Time Analysis (WCET 2024)

Abstract
With the increasing number of applications that require reliable runtime guarantees, the relevance of static worst-case analysis tools that can provide such guarantees increases. These analysis tools determine resource-consumption bounds of application tasks, with a model of the underlying hardware, to meet given resource budgets during runtime, such as deadlines of real-time tasks. This paper presents enhancements to the Platin worst-case analysis tool developed since its original release more than ten years ago. These novelties comprise Platin’s support for new architectures (i.e., ARMv6-M, RISC-V, and AVR) in addition to the previous backends for Patmos and ARMv7-M. Further, Platin now features system-wide analysis methods and annotation support to express system-level constraints. Besides an overview of these enhancements, we evaluate Platin’s accuracy for the two supported architecture implementations, Patmos and RISC-V.
Cite as

Emad Jacob Maroun, Eva Dengler, Christian Dietrich, Stefan Hepp, Henriette Herzog, Benedikt Huber, Jens Knoop, Daniel Wiltsche-Prokesch, Peter Puschner, Phillip Raffeck, Martin Schoeberl, Simon Schuster, and Peter Wägemann. The Platin Multi-Target Worst-Case Analysis Tool. In 22nd International Workshop on Worst-Case Execution Time Analysis (WCET 2024). Open Access Series in Informatics (OASIcs), Volume 121, pp. 2:1-2:14, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2024)

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@InProceedings{maroun_et_al:OASIcs.WCET.2024.2,
  author =	{Maroun, Emad Jacob and Dengler, Eva and Dietrich, Christian and Hepp, Stefan and Herzog, Henriette and Huber, Benedikt and Knoop, Jens and Wiltsche-Prokesch, Daniel and Puschner, Peter and Raffeck, Phillip and Schoeberl, Martin and Schuster, Simon and W\"{a}gemann, Peter},
  title =	{{The Platin Multi-Target Worst-Case Analysis Tool}},
  booktitle =	{22nd International Workshop on Worst-Case Execution Time Analysis (WCET 2024)},
  pages =	{2:1--2:14},
  series =	{Open Access Series in Informatics (OASIcs)},
  ISBN =	{978-3-95977-346-1},
  ISSN =	{2190-6807},
  year =	{2024},
  volume =	{121},
  editor =	{Carle, Thomas},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/OASIcs.WCET.2024.2},
  URN =		{urn:nbn:de:0030-drops-204704},
  doi =		{10.4230/OASIcs.WCET.2024.2},
  annote =	{Keywords: worst-case resource consumption, WCET, static analysis tool}
}
Document
DOI: 10.4230/LIPIcs.ECRTS.2024.10
Crêpe: Clock-Reconfiguration-Aware Preemption Control in Real-Time Systems with Devices

Authors: Eva Dengler and Peter Wägemann

Published in: LIPIcs, Volume 298, 36th Euromicro Conference on Real-Time Systems (ECRTS 2024)

Abstract
The domain of energy-constrained real-time systems that are operated on modern embedded system-on-chip (SoC) platforms brings numerous novel challenges for optimal resource minimization. These modern hardware platforms offer a heterogeneous variety of features to configure the tradeoff between temporal performance and energy efficiency, which goes beyond the state-of-the-art of existing dynamic-voltage-frequency-scaling (DVFS) scheduling schemes. The control center for configuring this tradeoff on platforms are complex clock subsystems that are intertwined with requirements of the SoC’s components (e.g., transceiver/memory/sensor devices). That is, several devices have precedence constraints with respect to specific clock sources and their settings. The challenge of dynamically adapting the various clock sources to select resource-optimal configurations becomes especially challenging in the presence of asynchronous preemptions, which are inherent to systems that use devices. In this paper, we present Crêpe, an approach to clock-reconfiguration-aware preemption control: Crêpe has an understanding of the target platform’s clock subsystem, its sleep states, and penalties to reconfigure clock sources for adapting clock frequencies. Crêpe’s hardware model is combined with an awareness of the application’s device requirements for each executed task, as well as possible interrupts that cause preemptions during runtime. Using these software/hardware constraints, Crêpe employs, in its offline phase, a mathematical formalization in order to select energy-minimal configurations while meeting given deadlines. This optimizing formalization, processed by standard mathematical solver tools, accounts for potentially occurring interrupts and the respective clock reconfigurations, which are then forwarded as alternative schedules to Crêpe’s runtime system. During runtime, the dispatcher assesses these offline-determined alternative schedules and reconfigures the clock sources for energy minimization. We developed an implementation based on a widely-used SoC platform (i.e., ESP32-C3) and an automated testbed for comprehensive energy-consumption evaluations to validate Crêpe’s claim of selecting resource-optimal settings under worst-case considerations.
Cite as

Eva Dengler and Peter Wägemann. Crêpe: Clock-Reconfiguration-Aware Preemption Control in Real-Time Systems with Devices. In 36th Euromicro Conference on Real-Time Systems (ECRTS 2024). Leibniz International Proceedings in Informatics (LIPIcs), Volume 298, pp. 10:1-10:25, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2024)

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@InProceedings{dengler_et_al:LIPIcs.ECRTS.2024.10,
  author =	{Dengler, Eva and W\"{a}gemann, Peter},
  title =	{{Cr\^{e}pe: Clock-Reconfiguration-Aware Preemption Control in Real-Time Systems with Devices}},
  booktitle =	{36th Euromicro Conference on Real-Time Systems (ECRTS 2024)},
  pages =	{10:1--10:25},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-324-9},
  ISSN =	{1868-8969},
  year =	{2024},
  volume =	{298},
  editor =	{Pellizzoni, Rodolfo},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.ECRTS.2024.10},
  URN =		{urn:nbn:de:0030-drops-203135},
  doi =		{10.4230/LIPIcs.ECRTS.2024.10},
  annote =	{Keywords: energy-constrained real-time systems, time/energy tradeoff, system-on-chip, energy-aware real-time scheduling, resource minimization, preemption control, worst-case energy consumption (WCEC), worst-case execution time (WCET), static whole-system analysis}
}
Document
Artifact
DOI: 10.4230/DARTS.10.1.2
Crêpe: Clock Reconfigurability for Preemption Control (Artifact)

Authors: Eva Dengler and Peter Wägemann

Published in: DARTS, Volume 10, Issue 1, Special Issue of the 36th Euromicro Conference on Real-Time Systems (ECRTS 2024)

Abstract
With the emergence of embedded system-on-chip (SoC) platforms, the development of energy-constrained real-time systems brings numerous novel challenges for optimal resource consumption. On these modern hardware platforms, complex clock subsystems make it possible to tradeoff between temporal performance and energy efficiency by reconfiguring the system, which exceeds the state-of-the-art of existing dynamic-voltage-frequency-scaling (DVFS) scheduling schemes. On embedded real-time systems, the usage of the devices (e.g., transceiver/memory/sensor devices) is an essential component to be able to interact with the surrounding world. Each device has precedence constraints with respect to specific clock sources and their settings. Therefore, to select resource-optimal configurations, we need to adapt the clock subsystem, which becomes especially challenging in the presence of asynchronous preemptions, often found during device interaction. This artifact evaluation covers the work of Crêpe, an approach to clock-reconfiguration-aware preemption control on systems with devices. Crêpe makes use of the target platform’s clock subsystem, possible idle modes, and the reconfiguration penalties for adapting the clock subsystem. By combining a hardware model for the device under investigation with an awareness of the required clock configuration for each task, as well as possible interrupts causing preemptions during runtime, Crêpe employs a mathematical formalization to determine energy-minimal configuration sequences while meeting all given deadlines. Before runtime, Crêpe solves the mathematical problem with standard mathematical solver tools and generates optimal execution strategies and clock-system reconfigurations before runtime. These offline-generated schedules are then assessed by the dispatcher during runtime, leading to an overall minimized energy consumption with minimal overhead during execution. Crêpe also consists of an implementation based on a widely-used SoC platform (i.e., ESP32-C3) and an automated testbed for comprehensive energy-consumption evaluations. This artifact evaluation makes use of these to validate Crêpe’s claim of selecting resource-optimal settings under worst-case considerations by reproducing our results shown in the related Crêpe paper [Eva Dengler and Peter Wägemann, 2024].
Cite as

Eva Dengler and Peter Wägemann. Crêpe: Clock Reconfigurability for Preemption Control (Artifact). In Special Issue of the 36th Euromicro Conference on Real-Time Systems (ECRTS 2024). Dagstuhl Artifacts Series (DARTS), Volume 10, Issue 1, pp. 2:1-2:3, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2024)

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@Article{dengler_et_al:DARTS.10.1.2,
  author =	{Dengler, Eva and W\"{a}gemann, Peter},
  title =	{{Cr\^{e}pe: Clock Reconfigurability for Preemption Control (Artifact)}},
  pages =	{2:1--2:3},
  journal =	{Dagstuhl Artifacts Series},
  ISBN =	{978-3-95977-327-0},
  ISSN =	{2509-8195},
  year =	{2024},
  volume =	{10},
  number =	{1},
  editor =	{Dengler, Eva and W\"{a}gemann, Peter},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/DARTS.10.1.2},
  URN =		{urn:nbn:de:0030-drops-203244},
  doi =		{10.4230/DARTS.10.1.2},
  annote =	{Keywords: energy-constrained real-time systems, time/energy tradeoff, system-on-chip, energy-aware real-time scheduling, resource minimization, preemption control, worst-case energy consumption (WCEC), worst-case execution-time (WCET), static whole-system analysis}
}
Document
Artifact
DOI: 10.4230/DARTS.9.1.2
FusionClock: WCEC-Optimal Clock-Tree Reconfigurations (Artifact)

Authors: Eva Dengler, Phillip Raffeck, Simon Schuster, and Peter Wägemann

Published in: DARTS, Volume 9, Issue 1, Special Issue of the 35th Euromicro Conference on Real-Time Systems (ECRTS 2023)

Abstract
Numerous embedded real-time systems have, besides their worst-case execution time (WCET) requirements, strict worst-case energy consumption (WCEC) constraints that must be satisfied. 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 for each connected device (i.e., memory, sensors, transceivers). Existing energy-aware scheduling approaches have limitations with regard to these modern, feature-rich clock trees: These shortcomings concern the (re-)configuration of the clock tree with the associated penalties, which are a non-negligible part of dynamic frequency/voltage scaling or power-gating devices in addition to the influence of available sleep modes. This artifact evaluation covers the work on 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.
Cite as

Eva Dengler, Phillip Raffeck, Simon Schuster, and Peter Wägemann. FusionClock: WCEC-Optimal Clock-Tree Reconfigurations (Artifact). In Special Issue of the 35th Euromicro Conference on Real-Time Systems (ECRTS 2023). Dagstuhl Artifacts Series (DARTS), Volume 9, Issue 1, pp. 2:1-2:3, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2023)

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@Article{dengler_et_al:DARTS.9.1.2,
  author =	{Dengler, Eva and Raffeck, Phillip and Schuster, Simon and W\"{a}gemann, Peter},
  title =	{{FusionClock: WCEC-Optimal Clock-Tree Reconfigurations (Artifact)}},
  pages =	{2:1--2:3},
  journal =	{Dagstuhl Artifacts Series},
  ISSN =	{2509-8195},
  year =	{2023},
  volume =	{9},
  number =	{1},
  editor =	{Dengler, Eva and Raffeck, Phillip and Schuster, Simon and W\"{a}gemann, Peter},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/DARTS.9.1.2},
  URN =		{urn:nbn:de:0030-drops-180238},
  doi =		{10.4230/DARTS.9.1.2},
  annote =	{Keywords: energy-constrained real-time systems, worst-case execution time (WCET), worst-case energy consumption (WCEC), energy-aware real-time scheduling, static whole-system analysis, time/energy tradeoff, clock tree, system on chip}
}
Document
DOI: 10.4230/LIPIcs.ECRTS.2023.6
FusionClock: Energy-Optimal Clock-Tree Reconfigurations for Energy-Constrained Real-Time Systems

Authors: Eva Dengler, Phillip Raffeck, Simon Schuster, and Peter Wägemann

Published in: LIPIcs, Volume 262, 35th Euromicro Conference on Real-Time Systems (ECRTS 2023)

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.
Cite as

Eva Dengler, Phillip Raffeck, Simon Schuster, and Peter Wägemann. FusionClock: Energy-Optimal Clock-Tree Reconfigurations for Energy-Constrained Real-Time Systems. In 35th Euromicro Conference on Real-Time Systems (ECRTS 2023). Leibniz International Proceedings in Informatics (LIPIcs), Volume 262, pp. 6:1-6:23, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2023)

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@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/entities/document/10.4230/LIPIcs.ECRTS.2023.6},
  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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