• Title, Summary, Keyword: Real-time

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On Benchmarking of Real-time Mechanisms in Various Periodic Tasks for Real-time Embedded Linux (실시간 임베디드 리눅스에서 다양한 주기적 타스크의 실시간 메커니즘 성능 분석)

  • Koh, Jae-Hwan;Choi, Byoung-Wook
    • The Journal of Korea Robotics Society
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    • v.7 no.4
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    • pp.292-298
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    • 2012
  • It is a real-time system that the system correctness depends not only on the correctness of the logical result of the computation but also on the result delivery time. Real-time Operating System (RTOS) is a software that manages the time of a microprocessor to ensure that the most important code runs first so that it is a good building block to design the real-time system. The real-time performance is achieved by using real-time mechanisms through data communication and synchronization of inter-task communication (ITC) between tasks. Therefore, test on the response time of real-time mechanisms is a good measure to predict the performance of real-time systems. This paper aims to analysis the response characteristics of real-time mechanisms in kernel space for real-time embedded Linux: RTAI and Xenomai. The performance evaluations of real-time mechanism depending on the changes of task periods are conducted. Test metrics are jitter of periodic tasks and response time of real-time mechanisms including semaphore, real-time FIFO, Mailbox and Message queue. The periodicity of tasks is relatively consistent for Xenomai but RTAI reveals smaller jitter as an average result. As for real-time mechanisms, semaphore and message transfer mechanism of Xenomai has a superior response to estimate deterministic real-time task execution. But real-time FIFO in RTAI shows faster response. The results are promising to estimate deterministic real-time task execution in implementing real-time systems using real-time embedded Linux.

Kernel Thread Scheduling in Real-Time Linux for Wearable Computers

  • Kang, Dong-Wook;Lee, Woo-Joong;Park, Chan-Ik
    • ETRI Journal
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    • v.29 no.3
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    • pp.270-280
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    • 2007
  • In Linux, real-time tasks are supported by separating real-time task priorities from non-real-time task priorities. However, this separation of priority ranges may not be effective when real-time tasks make the system calls that are taken care of by the kernel threads. Thus, Linux is considered a soft real-time system. Moreover, kernel threads are configured to have static priorities for throughputs. The static assignment of priorities to kernel threads causes trouble for real-time tasks when real-time tasks require kernel threads to be invoked to handle the system calls because kernel threads do not discriminate between real-time and non-real-time tasks. We present a dynamic kernel thread scheduling mechanism with weighted average priority inheritance protocol (PIP), a variation of the PIP. The scheduling algorithm assigns proper priorities to kernel threads at runtime by monitoring the activities of user-level real-time tasks. Experimental results show that the algorithms can greatly improve the unexpected execution latency of real-time tasks.

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Performance Evaluation of Real-time Mechanisms for Real-time Embedded Linux (실시간 임베디드 리눅스의 실시간 메커니즘 성능 분석)

  • Koh, Jae-Hwan;Choi, Byoung-Wook
    • Journal of Institute of Control, Robotics and Systems
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    • v.18 no.4
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    • pp.337-342
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    • 2012
  • This paper presents performance evaluation of real-time mechanisms for real-time embedded linux. First, we presents process for implementing open-source real-time embedded linux namely RTAI and Xenomai. These are real-time extensions to linux kernel and we implemented real-time embedded linux over the latest linux kernel. Measurements of executions of real-time mechanisms for each distribution are performed to give a quantitative comparison. Performance evaluations are conducted in kernel space about repeatability of periodic task, response time of Semaphore, FIFO, Mailbox and Message queue in terms of inter-task communication for each distribution. These rules can be helpful for deciding which real-time linux extension should be used with respect to the requirements of the real-time applications.

All Implementation and Performance Analysis of Priority Model of Real-Time CORBA (실시간 CORBA의 우선순위 모델 구현 및 성능분석)

  • 박순례;정선태
    • 제어로봇시스템학회:학술대회논문집
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    • pp.89-89
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    • 2000
  • The Current CORBA has many drawbacks to be deployed successfully in real-time system applications. Recently, OMG adopted Real-Time CORBA specification. In this paper, we report our efforts on an implementation of Priority Model of Real-Time CORBA spec., which is one of the most important components in Real-Time CORBA spec. The improvement of real-time performances of our implementation is verified experiments.

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Design and Implementation of Hard Embedded Real-Time System (경성 내장형 실시간 시스템의 설계 및 구현)

  • Lin, Chi-Ho
    • Journal of IKEEE
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    • v.5 no.2
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    • pp.164-173
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    • 2001
  • In this paper, we have designed and implemented a new hard embedded real-time system to satisfy hard real-time constraints in moving independently. Real-time kernel should be small size, fast and predictable. Because of the great variety of demands on real time scheduling, a real time kernel should also include a flexible and re-programmable task scheduling discipline. In this paper, we present that real-time applications should be split into small and simple parts with hard real-time constraints. To satisfy these properties, we designed real-time kernel and general kernel, that have their different properties. In real-time tasks, interrupt processing should be run. In general kernel, non real time tasks or general tasks are run. The efficiency of the proposed hard embedded real-time system is shown by comparison results for performance of the proposal real time kernel with both RT-Linux and QNX.

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Implementation of a network-based Real-Time Embedded Linux platform

  • Choi, Byoung-Wook;Shin, Eun-Cheol;Lee, Ho-Gil
    • 제어로봇시스템학회:학술대회논문집
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    • pp.1840-1845
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    • 2005
  • The SoC and digital technology development recently enabled the emergence of information devices and control devices because the SoC present many advantages such as lower power consumption, greater reliability, and lower cost. It is required to use an embedded operating system for building control systems. So far, the Real-Time operating system is widely used to implement a Real-Time system since it meets developer's requirements. However, Real-Time operating systems reveal a lack of standards, expensive development, and license costs. Embedded Linux is able to overcome these disadvantages. In this paper, the implementation of control system platform using Real-Time Embedded Linux is described. As a control system platform, we use XScale of a Soc and build Real-Time control platform using RTAI and Real-Time device driver. Finally, we address the feasibility study of the Real-Time Embedded Linux as a Real-Time operating system for mobile robots.

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The Implementation and Performance Testing of Real Time Information Processing System (실시간 정보처리 시스템 구축 및 성능 검증)

  • Jeong, Yoon-Seok;Kim, In-Su;Kim, Tae-Wan;Kim, Kee-Cheon;Chang, Chun-Hyon
    • The KIPS Transactions:PartA
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    • v.8A no.4
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    • pp.353-358
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    • 2001
  • In recent days, pc can process many things that mainframe have processed. Especially, in the transition from mainframe to pc, industries have needed the capabilities of Real Time information processing and Real Time monitoring for information control. But to support Real Time properties, it's needed to add Real Time modules and verify them. In this dissertation, we implemented and verified the Real Time System to support Real Time property. In addition, we implemented Web-based Real Time Monitoring System for Real Time information monitoring.

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Implementation of a Mobile Robot Control Platform using Real-Time Embedded Linux (실시간 임베디드 리눅스를 이용한 이동 로봇 플랫폼 구현)

  • Choi Byoung-Wook;Shin Eun-Cheol
    • Journal of Institute of Control, Robotics and Systems
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    • v.12 no.2
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    • pp.194-200
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    • 2006
  • The SoC and digital technology development recently enabled the emergence of information devices and control devices because the SoC presents many advantages such like lower power consumption, greater reliability, and lower cost. However, it is nearly impossible to use the SoC without operating systems because the SoC is included with many peripherals and complex architecture. It is required to use embedded operating systems and real-time operating systems may be used as an embedded operating system. So far, real-time operating systems are widely used to implement a Real-Time system since it meets developer's requirements. However, real-time operating systems have disadvantages including a lack of standards, expensive development, and license. Embedded Linux is able to overcome their disadvantages. In this paper, the implementation of control system platform for a mobile robot using real-time Embedded Linux is described. As a control hardware system platform, XScale board is used. As the real-time Embedded Linux, RTAI is adopted which is open source and royalty free, and supports various architectures and real-time devices, such like real-time CAN and real-time COM. This paper shows the implementation of RTAI on XScale board that means the porting procedure. We also applied the control system platform to the mobile robot and compared the Real-Time serial driver with non real-time serial driver. Experimental results show that that using RTAI is useful to build real-time control system with powerful functionalities of Linux.

PROFIBUS에서 대역폭 할당 기법 구현

  • 김지용;홍승호
    • 제어로봇시스템학회:학술대회논문집
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    • pp.97-100
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    • 1997
  • Fieldbuses are used as the lowest level communication network for real-time communication in factory automation and process control systems. Data generated from field devices can be divided into three categories: sporadic real-time, periodic real-time and non real-time data. Since these data share one fieldbus network medium, it needs a method that allocate the limited bandwidth of fieldbus network to the sporadic real-time, periodic real-time and non real-time traffic. This paper introduces an implementation method of bandwidth allocation scheme introduced in [51 on PROFIBUS. Using the modified PROFIBUS FDL(Fieldbus Data Link layer), the bandwidth allocation scheme introduced in [51 is verified by the experiments.

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Application of Real-time embedded linux as an operating system for intelligence robots (지능형 로봇 운영체제로서의 실시간 임베디드 리눅스 적용 방법)

  • Choi, Byoung-Wook;Park, Jeong-Ho;Yi, Soo-Yeong
    • Proceedings of the KIEE Conference
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    • pp.184-186
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    • 2007
  • Currently many sensors and processing data in a robot based on USN environments need to real-time features. In this paper, we examine recent research trends on real-time operating systems, especially on real-time embedded Linux, RTAI and Xenomai, for intelligent robots. Xenomai is a real-time development framework and have special feature supporting RTAI, VxWorks, pSOS+ etc. through the "skin". This research gives a guide to researcher in using real-time embedded Linux in the sense of architecture, supporting real-time mechanisms, kinds of real-time device driver, performances.

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