嵌入式实时系统调度策略

嵌入式系统在当今的生产和生活中得到了广泛的应用,鉴于嵌入式实时系统的特点,要求任务调度等实时内核功能精简和高效,综合了EDF和RM调度策略的CSD调度策略,更加适合嵌入式系统的特点,满足其内核的要求。     

嵌入式实时系统中断管理技术研究

嵌入式实时系统中断管理技术直接影响到系统的实时响应性能。本文通过对嵌入式内核中断管理技术的研究,归结出“中断前-后段处理”模型;同时,针对一些处理器中多个外部中断共用一个向量的问题,提出一种单向量多中断处理映射技术,并在PowerPCMPC860处理器上实现DeltaOS内核时,验证此技术的有效性。     

嵌入式实时系统的检验技术

检验是产品周期的最后一个阶段,特别在要求高可靠性时要给予特别的关注.本文提出一种新的检验方法来避免嵌入式系统的实时要求带来的复杂性.     

嵌入式分布实时系统自适应资源管理架构

分析了开放嵌入式分布实时(Distributed Real-time and Embedded,DRE)系统的自适应资源管理需求,针对传统静态资源管理方法的不足,提出了一种面向开放DRE系统的自适应资源管理架构;该架构采用动态任务管理、实时资源分配和自适应控制三种关键技术,能够更加适用于开放、动态的环境,有效应对资源约束和资源状态、应用程序QoS的变化;提高系统性能和稳定性;屏蔽底层硬件资源的异构性,为上层应用提供统一的服务接口。     

Windows NT—新的嵌入式与实时系统的开发平台

扼要地说明了ＷｉｎｄｏｗｓＮＴ作为嵌入式与实时系统的开发平台的可行性及其特点，以作为开发人员在平台选择时的参考。     

基于反馈控制的嵌入式实时系统调度算法设计

针对嵌入式实时系统在系统负载模型不确定的情况下系统的实时任务错过率过高以及调度稳定性差的问题,提出了一个基于反馈控制的调度模型.该模型主要由改进的多级队列调度器和3个控制器(准入控制器、执行等级控制器、比例积分微分(PID)控制器)组成.任务的错过率偏差反馈到PID控制器,产生相应的调整量并作用于其他两个控制器,对实时任务的执行等级进行调整, 经过调整的任务被调度器调度执行.在对模型中每个部件进行了一些结构调整和改进设计之后,将该调度模型应用于嵌入式可配置操作系统(eCos)中.实验结果表明,该模型降低了任务的时限错过率,同时解决了系统频频超载的问题.     

嵌入式实时系统RTLINUX的实现和测试

RTLINUX是LINUX的嵌入式实时核心,该文首先深入地分析RTLINUX的实现原理和机制,给出了在RTLIN UX下编写实时应用程序的方法。并在此基础上,设计和实现了测试RTLINUX实时性能的系统,并对测试结果进行了分析。     

嵌入式实时系统及其在烟机中的应用

近年来,嵌入式实时系统已经在工业等各个领域得到广泛关注与应用.本文介绍嵌入式实时系统的特点、关键技术、优势,以及嵌入式实时系统在高档卷接设备和包装设备中的应用情况;展望嵌入式实时系统的发展趋势及在烟机上的应用前景.     

嵌入式实时系统中的优先级反转问题

嵌入式实时系统中由于多任务共享资源,通常会出现一些奇怪的现象。本文就什么是优先级 反转及其产生原因进行分析,并提出2个行之有效的解决方案。     

A Framework for Software Fault Tolerance in Real-Time Systems

Real-time systems often have very high reliability requirements and are therefore prime candidates for the inclusion of fault tolerance techniques. In order to provide tolerance to software faults, some form of state restoration is usually advocated as a means of recovery. State restoration can be expensive and the cost is exacerbated for systems which utilize concurrent processes. The concurrency present in most real-time systems and the further difficulties introduced by timing constraints suggest that providing tolerance for software faults may be inordinately expensive or complex. We believe that this need not be the case, and propose a straightforward pragmatic approach to software fault tolerance'which is believed to be applicable to many real-time systems. The approach takes advantage of the structure of real-time systems to simplify error recovery, and a classification scheme for errors is introduced. Responses to each type of error are proposed which allow service to be maintained.     

A Real-Time Framework for Model-Predictive Control of Continuous-Time Nonlinear Systems

A new formulation of model-predictive control (MPC) for continuous-time nonlinear systems is developed, which allows for the use of ldquoreal-timerdquo (RT) optimization techniques in which the solution to the finite-horizon optimal control problem (OPC) evolves within the same timescale as the process dynamics. The computational savings of the RT solver are enhanced by the unique framework within which the OPC is posed, enabling significant reduction in the dimensionality of the search for situations where computational speed takes priority over optimality of the solutions. This framework, and its associated proof of stability, encompasses results on sampled-data (SD) nonlinear model-predictive control (NMPC) implementation as a special case.     

Implementation of Hard Real-Time Embedded Control Systems

Although the domain of hard real-time systems has been thoroughly elaborated in the academic sphere, embedded computer control systems –- being an important component in mechatronic designs –- are seldom dealt with consistently. Often, off-the-shelf computer systems are used, with no guarantee that they will be able to meet the requirements specified. In this paper, a design for embedded control systems is presented. Particularly, the paper deals with the hardware architecture and design details, the operating system, and high-level real-time language support. It is shown how estimates of process run-times necessary for schedulability analysis can be acquired on the basis of deterministic behavior of the hardware platform.     

复杂实时嵌入式系统建模与设计方法研究

提出了一种面向角色(Actor-Oriented)的复杂实时嵌入式系统建模与设计方法．该方法首先根据不同的计算模型(Computation Model)和不同的抽象层次(Abstract Hierarchy)将嵌入式系统划分为多个具有单一计算模型的子系统，然后按某一领域的专业知识构造这些子系统．再将这些子系统综合成一个整体模型，加以仿真．最后从调试好的模型自动生成软件代码和硬件描述语言，从而完成设计工作．还介绍了面向角色集成开发环境，并根据实例分析了该方法的有效性和优点。     

Graduate Courses in Embedded and Real-Time Systems

This issue's column describes two courses taught at Anna University, India. The courses' topics are embedded and real-time systems with an emphasis on pervasive computing applications.     

A Planning Framework for Systems Development Projects

As part of any systems development project, JS professionals must perform a variety of tasks. One such important task, estimating, is often done incorrectly and, as a result, can lead to errors in the final system or a cancellation of the project. To estimate projects accurately, data on previous project estimates should be readily available. This article describes a systems development planning framework that essentially creates an estimating knowledge data base, which enables IS managers to prepare better project plans.     

Verification Approach of Metropolis Design Framework for Embedded Systems

In this paper, we focus on the verification approach of Metropolis, an integrated design framework for heterogeneous embedded systems. The verification approach is based on the formal properties specified in Linear Temporal Logic (LTL) or Logic of Constraints (LOC). Designs may be refined due to synthesis or be abstracted for verification. An automatic abstraction propagation algorithm is used to simplify the design for specific properties. A user-defined starting point may also be used with automatic propagation. Two main verification techniques are implemented in Metropolis the formal verification utilizing the model checker Spin and the simulation trace checking with automatic generated checkers. Translation algorithms from specification models to verification models, as well as algorithms of generated checkers are discussed. We use several case studies to demonstrate our approach for verification of system level designs at multiple levels of abstraction.     

嵌入式系统的动态电源管理架构

分析嵌入式系统对动态电源管理的需求,并在此基础上提出了与之适应的,以策略框架为中心的系统级动态电源管理架构。利用这种构架可以整合针对不同组件的动态电源管理算法和机制,从系统的角度进行行之有效的管理。该构架应用于TD-SCDMA无线终端上,平均能耗下降了50%,取得良好的效果。     

A Framework for Composing Real-Time Schedulers

In this paper, we present a framework for integrating real-time components in the same system, where each component has its own scheduling algorithm. There are two main reasons for this research: to allow maximum flexibility in the design of systems with different real-time activities and to reuse already existing applications without changing their scheduling policy. After defining the concept of component in our context, we present our methodology that is based on a two-level hierarchical scheduling paradigm. At the global level, a scheduler selects which component must be executed at each instant; the selected component then chooses which task has to be scheduled depending on its own scheduling strategy.