Interaction-Level Specialization of RISC-V Soft Cores for Zephyr RTOS with ARA

• Typ der Arbeit: Masterarbeit
• Status der Arbeit: laufend
• Projekte: AHA
• Betreuer: Andreas Kässens, Daniel Lohmann
• Bearbeiter: Tim Schubert

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Context

Within the AHA project, we focus on optimizing embedded systems by specialization of the OS itself. Using the Automatic Real-time Analyzer (ARA), we perform static analysis to enable extensive tailoring of real-time operating systems (RTOS) to the application. The operating system is generated specifically for a single application to provide exactly the required functionality. As a result, we improve non-functional system properties like delay or memory footprint, which can reduce hardware costs and energy consumption. Not only the operating system can be specialized; it is also possible to specialize the underlying hardware as well.

Problem

The idea of pushing parts of the operating system into hardware is not new. There is a lot of related work, where parts of the OS like the scheduler are moved completely into hardware blocks next to the CPU. Compared to this approach, we target a much tighter integration, the interactions with specific instances could be moved right into the CPU pipeline. Using ARA, we can analyze those interactions and instances at compile-time, enabling the static specialization of the RTOS and the hardware ¹. Instead of high-level message queue operations like k_msgq_put() or k_msgq_get(), a single custom RISC-V instruction could be executed ². This will result in reduced jitter and optimized kernel path timing. Thus, a better Real-Time behavior is achieved by minimizing the worst-case execution time and improving the predictability.

Goal

The minimal goal of this thesis is to have interaction-specific specialized instructions for the Zephyr RTOS in the Vexriscv Soft Core ³. Using Python, the Vexriscv CPU can be modified to include custom instructions or registers. The Radiona ULX3S board is based on the Lattice ECP5 FPGA and supports single- and multicore VexRiscv-based systems and the required toolchain is Open-Source ⁴. In order to leverage the new instructions properly, the instance and interaction analysis results in ARA shall be transferred to the generation phase of the SoC.

Topics: Python, FPGA, RISC-V, Hardware, ISA, Real-Time Operating System

References

LCTES Conference A
OSEK-V: Application-Specific RTOS Instantiation in Hardware

Christian Dietrich, Daniel LohmannProceedings of the 2017 ACM SIGPLAN/SIGBED Conference on Languages, Compilers and Tools for Embedded Systems (LCTES '17)ACM Press2017.
PDF Raw Data 10.1145/3078633.3078637 [BibTex]

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BibTex Entry

@inproceedings{dietrich:17:lctes,
location = {New York, NY, USA},
ar = {25\% (13/56)},
author = {Christian Dietrich and Daniel Lohmann},
booktitle = {Proceedings of the 2017 ACM SIGPLAN/SIGBED Conference on Languages, Compilers and Tools for Embedded Systems (LCTES '17)},
category = {os-embedded, SRA},
doi = {10.1145/3078633.3078637},
entrysubtype = {Conference},
month = {June},
publisher = {ACM Press},
title = {{OSEK-V}: Application-Specific {RTOS} Instantiation in Hardware},
venue = {Barcelona, Spain},
year = {2017},
}

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RTAS Conference A
ARA: Static Initialization of Dynamically-Created System Objects

Björn Fiedler, Gerion Entrup, Christian Dietrich, Daniel LohmannProceedings of the 27th IEEE Real-Time and Embedded Technology and Applications Symposium (RTAS'21)2021.
PDF Details Video Teaser Video 10.1109/RTAS52030.2021.00039 [BibTex]

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BibTex Entry

@inproceedings{fiedler:21:rtas,
author = {Björn Fiedler and Gerion Entrup and Christian Dietrich and Daniel Lohmann},
booktitle = {Proceedings of the 27th IEEE Real-Time and Embedded Technology and Applications Symposium (RTAS'21)},
doi = {10.1109/RTAS52030.2021.00039},
entrysubtype = {Conference},
month = {May},
pages = {400–412},
title = {{ARA}: Static Initialization of Dynamically-Created System Objects},
venue = {Virtual Event},
year = {2021},
}

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Design und Implementierung eines Zephyr-RTOS-Modells für ARA zur statischen Whole-System-Analyse

Extend ARA - a (real-time) operating system (RTOS) analyzer - for analysis of Zephyr, an RTOS guided by the Linux Foundation

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Typ

Bachelorarbeit

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Status

abgeschlossen

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Supervisors

Gerion Entrup
Daniel Lohmann

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Project

AHA

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Bearbeiter

Kenny Albes (abgegeben: 28. Feb 2021)