嵌入式数据库系统存储研究与实现

嵌入式系统与网络技术以及数据库技术的结合可以极大地增强嵌入式设备的智能化与灵活性。将数据库系统移植到嵌入式设备中,可以方便、有效地管理嵌入式设备上的数据;文中讨论了嵌入式数据库中数据的存储模式及存储组织结构,并在优化存储性能的方面做了探讨。     

一种新的嵌入式Linux实时调度算法

针对现有实时调度算法在实时性能上的不足,提出了一种新的实时任务分类调度算法,根据实时任务的到达情况进行分类,划分为周期任务和非周期任务,并对不同类型的实时任务使用不同的改进的实时调度算法.通过实验,证明此算法与现有实时调度算法相比,综合实时性能有了很大程度的提高.     

嵌入式数字视频监控系统中的媒体存储研究

基于目前较流行的嵌入式数字视频监控系统,提出了一种媒体存储的策略。该策略通过设计双缓冲媒体流算法、设计硬盘预分配空间和连续文件存储、多路存储轮转式调度算法以及媒体信息索引等,在较高的媒体编码数据量下,实现了不丢帧的稳定存储,并能快速而准确地检索,清晰流畅地回放历史视频。在长时间的测试中验证了该存储策略的实用性和可靠性。     

Temperature-Aware Task Allocation and Scheduling for Embedded Multiprocessor Systems-on-Chip (MPSoC) Design

Temperature affects not only the performance but also the power, reliability, and cost of the embedded system. This paper proposes a temperature-aware task allocation and scheduling algorithm for MPSoC embedded systems. Thermal-aware heuristics are developed, and a temperature-aware floorplanning tool is used to reduce the peak temperature and achieve a thermally even distribution while meeting real time constraints. The paper investigates both power-aware and thermal-aware approaches to the task allocation and scheduling. The experimental results show that the thermal-aware approach outperforms the power-aware schemes in terms of maximal and average temperature reductions. To the best of our knowledge, this is the first MPSoC task allocation and scheduling algorithm that takes temperature into consideration.

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虚拟化技术在嵌入式系统中的应用

基于嵌入式系统对虚拟化环境的特殊要求,探讨如何设计虚拟机(VM)。针对工业实时控制,介绍了与第三方产品结合,把Intel虚拟化技术的好处拓展到应用中去。用虚拟化整合系统可以保证一定的实时性能;无需硬件冗余;进行软件移植而不简化应用。通过软件环境并行,虚拟化也允许原有的应用与新应用并存。它为多线程的应用在多核处理器上运行提供了途径。     

基于RT-CORBA的实时嵌入式系统开发

首先介绍了公共对象请求代理体系结构(RT-CORBA)规范,然后详细分析了RT-CORBA的特点,并提出了基于RT-CORBA的嵌入式系统开发的方法和途径。     

异构多处理器系统的混合任务调度算法

针对实时异构系统的任务调度问题,提出了一种异构多处理器系统的混合实时任务调度算法.该算法采用带有非周期服务器的EDF( Earliest Deadline First)算法来调度单处理器上的任务集,可充分利用处理器的计算带宽.采用启发式搜索算法来进行任务的分配,以最大剩余计算带宽为搜索指标,可确保各处理器的负载尽量平衡...     

设备级OS中任务调度的IO抖动优化策略

 为了减小任务调度产生的抖动对设备级操作系统的稳定性和可靠性的影响,提出了一种带有抢占阈值的任务分割模型RJPS.根据抢占阈值对任务调度的抖动与延迟的影响及该模型下任务可调度性的分析,分别设计了基于固定优先级调度和动态优先级调度策略的最小阈值分配算法.仿真结果表明,该模型可以在保证任务集可调度的前提下明显减少任务的IO抖动.     

Reliability-aware Co-synthesis for Embedded Systems

As technology scales, transient faults have emerged as a key challenge for reliable embedded system design. This paper proposes a design methodology that incorporates reliability into hardware–software co-design paradigm for embedded systems. We introduce an allocation and scheduling algorithm that efficiently handles conditional execution in multi-rate embedded systems, and selectively duplicates critical tasks to detect or correct transient errors, such that the reliability of the system is improved. Two methods are proposed to insert duplicated tasks into the schedule. The improved reliability is achieved by utilizing the otherwise idle computation resources and taking advantage of the overlapping schedule for mutually exclusive tasks in the conditional task graph, such that it incurs no resource or performance penalty.

Hardware‐Aware Rate Monotonic Scheduling Algorithm for Embedded Multimedia Systems

Many embedded multimedia systems employ special hardware blocks to co‐process with the main processor. Even though an efficient handling of such hardware blocks is critical on the overall performance of real‐time multimedia systems, traditional real‐time scheduling techniques cannot afford to guarantee a high quality of multimedia playbacks with neither delay nor jerking. This paper presents a hardware‐aware rate monotonic scheduling (HA‐RMS) algorithm to manage hardware tasks efficiently and handle special hardware blocks in the embedded multimedia system. The HA‐RMS prioritizes the hardware tasks over software tasks not only to increase the hardware utilization of the system but also to reduce the output jitter of multimedia applications, which results in reducing the overall response time.     

Scenario Selection and Prediction for DVS-Aware Scheduling of Multimedia Applications

Modern multimedia applications usually have real-time constraints and they are implemented using application-domain specific embedded processors. Dimensioning a system requires accurate estimations of resources needed by the applications. Overestimation leads to over-dimensioning. For a good resource estimation, all the cases in which an application can run must be considered. To avoid an explosion in the number of different cases, those that are similar with respect to required resources are combined into, so called application scenarios. This paper presents a methodology and a tool that can automatically detect the most important variables from an application and use them to select and dynamically predict scenarios, with respect to the necessary time budget, for soft real-time multimedia applications. The tool was tested for three multimedia applications. Using a proactive scenario-based dynamic voltage scheduler based on the scenarios and the runtime predictor generated by our tool, the energy consumption decreases with up to 19%, while guaranteeing a frame deadline miss ratio close to zero.

硬盘播出系统中的存储技术

存储技术是电视台硬盘播出系统中的关键环节，关系到整个系统的性能以及系统安全高效的运行。从存储方式、存储架构、Raid技术、接口通道等方面介绍硬盘播出系统中的存储技术。     

嵌入式实时MPEG-2以太网传输系统的设计

介绍了一种实时MPEG-2以太网传输系统的设计方案,它由硬件MPEG-2编/解码卡和基于ARM处理器的嵌入式系统卡构成,前者用于视音频的实时压缩编码和解码,后者将MPEG-2数据流进行IP封装和解封装,还分析了IP网络传输对接收端MPEG-2解码视音频的影响,并设计了一些测评方法对系统进行了相关测评.     

嵌入式软件系统的一种层次设计方法

嵌入式软件系统一般由实时操作系统、应用层软件及硬件驱动软件等部分构成。本文提出了一种应用在嵌入式软件系统开发中的层次设计方法，采用模块化的软件设计思想，将嵌入式软件系统分为不同的功能模块，不同的软件模块负责不同的功能。设计的总体原则是使嵌入式软件系统具有易移植、可复用、与平台无关等特点。这样可以满足现代大规模软件开发的需求，缩短软件的开发时间，便于软件的管理和控制，从而大大提高软件的质量。     

嵌入式数据库的研究

随着便携式计算设备和无线通讯技术的发展,嵌入式数据库技术已经成为一个十分活跃的研究领域,并引起了越来越广泛的关注。本文阐述了嵌入式数据库的概念、背景及其特点,描述了嵌入式系统的研究目标和系统模型,并探讨了嵌入式数据库的几种关键技术。     

基于嵌入式系统的实时控制模块设计与实现

提出一个使用C51单片机的嵌入式系统在通信测试仪器中实现实时控制功能的案例,给出了硬件及软件设计方案,并指出了设计中需注意的问题。该设计成功地应用于某通信测试仪器中,较好地实现了预期的目标。     

Hardware-Software Partitioning for Real-Time Embedded Systems

In this paper, we present an approach to hardware-software partitioning for real-time embedded systems. Hardware and software components are modeled at the system level, so that cost and performance tradeoffs can be studied early in the design process and a large design space can be explored. Feasibility factor is introduced to measure the possibility of a real-time system being feasible, and is used as both a constraint and an attribute during the optimization process. An imprecise value function is employed to model the tradeoffs among multiple performance attributes. Optimal partitioning is achieved through the use of an existing computer-aided design tool. We demonstrate the application of our approach through the design of an example embedded system.     

A Novel Reconfigurable Wrapper for Testing of Embedded Core-Based SOCs and its Associated Scheduling Algorithm

In this paper a mathematical formulation and an efficient solution, of the embedded core-based system-on-chip (SOC) test scheduling problem (ECTSP) is presented. The ECTSP can be stated as follows; given a chip with N _C cores each having a test T _i; where T _i takes time to execute on a test access mechanism (TAM) of width w _j, and a constraint W on the number of top-level test pins; calculate the TAM assignment vector and the schedule for each test T _i, such that the completion time of the full chip test is minimized. All existing approaches have solved the ECTSP by solving the TAM partition and scheduling problem sequentially. In this paper we present an unified approach to solve the ECTSP. We present the first report of a design of reconfigurable core wrapper which allows for a dynamic change in the width of the test access mechanism (TAM) executing a core test. An automatic procedure for the creation of DfT hardware required for reconfiguration using a graph theoretic representation of core wrappers is also presented. For the case of reconfigurable wrappers, efficient algorithms to compute the schedule are presented based upon some recent results in the field of malleable task scheduling. Cases in which the degree of reconfigurability are constrained are considered; the case when only a single core can have reconfigurable wrapper, a schedule with zero TAM idle time can be found in time O(N _C(N _C + W)lgW), and the case when only 2 different wrapper configurations are allowed can be solved in time O(N _C ³). Comparison with existing results on benchmark SOCs show that our algorithms outperform state-of-art ILP formulations not only in schedule makespan, but also significantly reduce computation time.     

数字视频监控系统中数据的存储算法

目前视频监控系统在多路存储情况下大多采用轮巡式,该存储方式效率低下,而且存在因硬盘剩余空间不足而造成的存储异常中断等问题.文中结合实际视频监控系统,讨论了视频数据的存储算法,采用多磁盘调度算法实现了将多路存储"平均"分配于多个硬盘中,充分提高存储访问的效率;并且设计实现了定时检测增加磁盘当前剩余空间算法,保证磁盘剩余空间始终维持在一定的容量,从而很好地解决了存储异常中断的问题.     

一种面向通信设备的嵌入式软件平台

文章介绍了一种应用于通信设备中的嵌入式软件平台,在给出了嵌入式软件平台的体系架构的基础上,从嵌入式实时操作系统、符合通信行业需求的定制组件和中间件、通信应用软件的集成开发环境3个层面对嵌入式软件平台的关键技术和特点进行了描述,并分析了嵌入式软件平台的经济价值和社会效益.