scholarly journals Real-Time Performance and Response Latency Measurements of Linux Kernels on Single-Board Computers

Computers ◽  
2021 ◽  
Vol 10 (5) ◽  
pp. 64
Author(s):  
George K. Adam
Keyword(s):  
Real Time ◽  
Safety Margin ◽  
Evaluation Methodology ◽  
Raspberry Pi ◽  
Performance Measurements ◽  
Worst Case ◽  
Time Performance ◽  
Software Modules ◽  
Real Time Applications ◽  
Embedded Development

This research performs real-time measurements of Linux kernels with real-time support provided by the PREEMPT_RT patch on embedded development devices such as BeagleBoard and Raspberry Pi. The experimental measurements of the Linux real-time performance on these devices are based on real-time software modules developed specifically for the purposes of this research. Taking in consideration the constraints of the specific hardware platforms under investigation, new measurements software was developed. The measurement algorithms are designed upon response and periodic task models. Measurements investigate latencies of real-time applications at user and kernel space. An outcome of this research is that the proposed performance measurements approach and evaluation methodology could be applied and deployed on other Linux-based boards and platforms. Furthermore, the results demonstrate that the PREEMPT_RT patch overall improves the Linux kernel real-time performance compared to the standard one. The reduced worst-case latencies on such devices running Linux with real-time support could make them potentially more suitable for real-time applications as long as a latency value of about 160 μs, as an upper bound, is an acceptable safety margin.

scholarly journals Performance Assessment of Linux Kernels with PREEMPT_RT on ARM-Based Embedded Devices

Electronics ◽  
2021 ◽  
Vol 10 (11) ◽  
pp. 1331
Author(s):  
George K. Adam ◽  
Nikos Petrellis ◽  
Lambros T. Doulos
Keyword(s):  
Real Time ◽  
Performance Metrics ◽  
Evaluation Methodology ◽  
Performance Measurements ◽  
Periodic Tasks ◽  
Embedded Devices ◽  
Worst Case ◽  
Time Performance ◽  
Software Modules ◽  
Response Task

This work investigates the real-time performance of Linux kernels and distributions with a PREEMPT_RT real-time patch on ARM-based embedded devices. Experimental measurements, which are mainly based on heuristic methods, provide novel insights into Linux real-time performance on ARM-based embedded devices (e.g., BeagleBoard and RaspberryPi). Evaluations of the Linux real-time performance are based on specific real-time software measurement modules, developed for this purpose, and the use of a standard benchmark tool, cyclictest. Software modules were designed upon the introduction of a new response task model, an innovative aspect of this work. Measurements include the latency of response tasks at user and kernel space, the response on the execution of periodic tasks, the maximum sustained frequency and general latency performance metrics. The results show that in such systems the PREEMPT_RT patch provides more improved real-time performance than the default Linux kernels. The latencies and particularly the worst-case latencies are reduced with real-time support, thus making such devices running Linux with PREEMPT_RT more appropriate for use in time-sensitive embedded control systems and applications. Furthermore, the proposed performance measurements approach and evaluation methodology could be applied and deployed on other Linux-based real-time platforms.

scholarly journals Efficient Worst-Case Temperature Evaluation for Thermal-Aware Assignment of Real-Time Applications on MPSoCs

2013 ◽  
Vol 29 (4) ◽  
pp. 521-535 ◽  
Author(s):  
Lars Schor ◽  
Iuliana Bacivarov ◽  
Hoeseok Yang ◽  
Lothar Thiele
Keyword(s):  
Real Time ◽  
Worst Case ◽  
Real Time Applications

Novel prioritized LRU circuits for shared cache in computer systems

2020 ◽  
Vol 34 (23) ◽  
pp. 2050242
Author(s):  
Yao Wang ◽  
Lijun Sun ◽  
Haibo Wang ◽  
Lavanya Gopalakrishnan ◽  
Ronald Eaton
Keyword(s):  
Real Time ◽  
High Performance ◽  
Cmos Technology ◽  
Cache Replacement ◽  
Worst Case ◽  
Shared Cache ◽  
Cache Access ◽  
Worst Case Execution Time ◽  
Real Time Applications ◽  
Time Systems

Cache sharing technique is critical in multi-core and multi-threading systems. It potentially delays the execution of real-time applications and makes the prediction of the worst-case execution time (WCET) of real-time applications more challenging. Prioritized cache has been demonstrated as a promising approach to address this challenge. Instead of the conventional prioritized cache schemes realized at the architecture level by using cache controllers, this work presents two prioritized least recently used (LRU) cache replacement circuits that directly accomplish the prioritization inside the cache circuits, hence significantly reduces the cache access latency. The performance, hardware and power overheads due to the proposed prioritized LRU circuits are investigated based on a 65 nm CMOS technology. It shows that the proposed circuits have very low overhead compared to conventional cache circuits. The presented techniques will lead to more effective prioritized shared cache implementations and benefit the development of high-performance real-time systems.

scholarly journals Beyond the Traditional Analyses and Resource Management in Real-Time Systems

2022 ◽  
pp. 67-77
Author(s):  
Federico Reghenzani
Keyword(s):  
Real Time ◽  
Real Time Systems ◽  
Formal Proofs ◽  
Worst Case ◽  
Worst Case Execution Time ◽  
Quantitative Results ◽  
Real Time Applications ◽  
Hard Real Time ◽  
Phd Thesis ◽  
Time Systems

AbstractThe difficulties in estimating the Worst-Case Execution Time (WCET) of applications make the use of modern computing architectures limited in real-time systems. Critical embedded systems require the tasks of hard real-time applications to meet their deadlines, and formal proofs on the validity of this condition are usually required by certification authorities. In the last decade, researchers proposed the use of probabilistic measurement-based methods to estimate the WCET instead of traditional static methods. In this chapter, we summarize recent theoretical and quantitative results on the use of probabilistic approaches to estimate the WCET presented in the PhD thesis of the author, including possible exploitation scenarios, open challenges, and future directions.

scholarly journals Binocular intelligent following robot based on YOLO-LITE

2021 ◽  
Vol 336 ◽  
pp. 03002
Author(s):  
Yuanyuan Zheng ◽  
Jun Ge
Keyword(s):  
Neural Network ◽  
Real Time ◽  
Deep Neural Network ◽  
Frame Rate ◽  
Raspberry Pi ◽  
Detection Accuracy ◽  
Location Error ◽  
Embedded Devices ◽  
Robot System ◽  
Time Performance

In order to solve the problem that the deep neural network model is large in scale, the calculation time is too long, and the real-time performance is severely limited when combined with embedded devices, so studied the intelligent follower robot system based on YOLO-LITE algorithm combined with Raspberry Pi 3B+. The system mainly includes camera processing, target detection and other modules. Obtained the internal and external parameters of the camera through calibration, and according to these parameters to correct the binocular camera. Recognized and located the target in each frame of image, calculated the distance from the camera to the target and the center location error, and driven the car to move. The experimental results show that the following car has excellent real-time performance, the average detection frame rate can reach 20Fps, and the average detection accuracy can reach more than 80%.

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