基于指令距离的存储相关性预测方法

存储相关性预测对于减少存储相关性冲突、提高微处理器性能具有十分重要的作用。针对传统相关性预测器硬件开销大、可实现性较差的缺点,通过对存储相关性的局部性分析,提出了一种基于指令距离的存储相关性预测方法。该方法充分利用了发生存储相关性冲突的指令在指令距离上的局部性,预测冲突指令的指令距离,进而控制部分访存指令的发射时机,大大减少了存储相关性冲突的次数。实验结果表明,在硬件开销约为1KB的情况下,使用基于指令距离的相关性预测器后,每个时钟周期平均执行的指令数可以提高1.70%,最高可以提高5.11%。在硬件开销较小的情况下,较大程度提高了微处理器的性能。     

细粒度多线程处理器中前瞻性数据加载的设计与实现

细粒度多线程是一种典型的线程级并行性开发技术,通过每周期的线程切换来实现高吞吐率执行.设计并实现了一种细粒度多线程处理器中的前瞻性数据加载机制,该机制预测LOAD操作在数据cache命中,不立即进行线程切换,而是继续执行后续指令,并通过数据旁路解决相关性问题.实验结果表明前瞻性数据加载能明显提高访存性能,在一种配置下,...     

分片式处理器上的谓词执行技术优化

谓词执行能使分片式处理器充分利用众多的执行单元,开发指令级并行性.但因此形成的超块也使得分支误预测代价增大,所以提高分支预测器的性能至关重要.本文提出一种基于剖析信息决策的谓词执行技术,该技术利用剖析信息对谓词执行前后的执行周期进行估算,从而对分支的谓词执行进行决策.该技术使分支预测器的命中率提高了0.68%～3.50%,使系统性能提高了1.67%～8.33%.同时,利用select指令表示谓词化指令也消除了重命名阶段寄存器多定义问题.     

基于汇编代码的指令调度器的设计与实现

随着嵌入式处理器在各个领域的广泛应用,嵌入式软件的复杂度越来越高.充分发掘嵌入式处理器的性能,需要高级编译优化技术的支持.指令调度是编译器发掘程序指令级并行性的关键技术之一.设计并实现了一个基于汇编代码的指令调度器.实验结果表明,在TECC嵌入式编译器中集成指令调度器后可显著提高程序的性能.     

基于真实历史反馈的自适应值预测器的设计与优化

乱序超标量处理器所能获得的指令级并行能力越来越有限,为了获得更高的指令并行性,必须增加更多的乱序执行和控制资源.随着处理器架构的变化,值预测技术能够在现有主流处理器微架构的基础上以更少的硬件开销,获得更高的数据并行性,进一步提升处理器的乱序执行性能.提出了一种基于真实历史反馈的上下文值预测器(RH-VTAGE),通过设置失效列表和预测精度表来控制反馈RH-VTAGE的预测精度,减少预测失效时的流水线恢复开销.同时,在值预测器的最后阶段增加了真实历史反馈的控制计数器,并设计了自适应置信度控制逻辑,针对不同类型的指令按概率对置信度进行动态调整.实际测试结果表明,相对于其他预测器,RH-VTAGE的整数程序预测性能没有明显提升,但是对于浮点程序性能最大提升31.2％.     

面向VLIW DSP结构的编译器的设计与实现

VLIW编译器实现指令并行性挖掘、相关性检查、指令调度等职能,对VLIW处理器的性能影响较大.本文基于一款VLIW DSP芯片,利用可重定位编译器IMPACT的前端和代码生成器模板,设计和实现了高性能的VLIW编译器.利用伪数据类型和Intrinsic函数结合,在编译器中构建了对SIMD功能的支持.实验结果显示,对比基于GCC版本的编译器,该编译器生成的指令数平均下降42%,并行包数下降30%.     

指令调度中推断和推测技术的研究

编译器提高程序并行性的主要障碍是：频繁的控制转移和模棱两可的内存访问。推断和推测是vliw处理器体系结构的新特点，为了消除分支或访存对指令级并行性识别的影响。指令调度是编译器挖掘程序指令级并行性的关键技术之一，本文论述了如何在指令调度中有效地利用推断和推测技术，提高程序的性能。     

基于C6000的数据存储处理编程优化方法

针对TI TMS320C6000系列数字信号处理器容易忽视的CPU指令并行、软件流水特点和编译器内联函数、线性汇编及汇编语言的高速运行特点,给出常见的指令存储器相关性问题、循环冗余问题、嵌套循环的流水性能问题和程序存储块冲突问题的分析与优化解决方法。以定点点积算法进行参照实验,结果证明代码运行速度在进行相应C程序编程优化、线性汇编编程优化和手工汇编编程优化后最高分别可以提高85.9%、86.4%和93.1%。     

超标量处理器乱序提交机制的研究与设计

针对超标量处理器中长周期执行指令延迟退休及持续译码导致的重排序缓存（ROB）阻塞问题,提出一种指令乱序提交机制。通过设计容量可配置的多缓存指令提交结构,实现存储器操作指令和ALU类型指令的分类退休,根据超标量处理器架构及性能需求对目标缓存和存储缓存容量进行参数化配置降低流水线阻塞风险,同时利用指令目的寄存器编码提交模式加快指令提交速率。实验结果表明,该机制提高了单次指令提交数量,基于该机制的超标量处理器相比传统基于ROB顺序提交机制的超标量处理器在减少硬件开销的情况下平均IPC指数提升46%,相比基于值预测、乱序退休和组提交的超标量处理器平均IPC指数增益为19%,综合性能更优。     

基于数据流图的异构VLIW DSP分簇方法

超长指令字数字信号处理器(VLIW DSP)的指令级并行性(ILP)主要通过指令分簇和软件流水来实现。在以前的研究中,指令分簇主要只考虑指令级并行性和减少簇间转移指令,对异构体系结构和某些寄存器只能分在指定簇上的情况考虑较少。提出一种基于数据流图(DFG)的异构体系结构上的分簇方法,利用指令的相关性将DFG划分为与簇数目相同个数的子图,再根据特殊寄存器对簇的要求采用启发式算法对子图进行调整,实验结果表明这种分簇方法使得负载更均衡,加速比相对于传统方法可以提高8%左右。     

Only connect: teaching, technology and telesis

Abstract This paper describes an approach to the design of interactive multimedia materials being developed in a European Community project. The developmental process is seen as a dialogue between technologists and teachers. This dialogue is often problematic because of the differences in training, experience and culture between them. Conditions needed for fruitful dialogue are described and the generic model for learning design used in the project is explained.     

European Community policy and the market

Abstract This paper starts with some reflections on the policy considerations and priorities which are shaping European Commission (EC) research programmes. Then it attempts to position the current projects which seek to capitalise on information and communications technologies for learning in relation to these priorities and the apparent realities of the marketplace. It concludes that while there are grounds to be optimistic about the contribution EC programmes can make to the efficiency and standard of education and training, they are still too technology driven.     

一种自适应子融合集成多分类器方法

融合集成方法已经广泛应用在模式识别领域,然而一些基分类器实时性能稳定性较差,导致多分类器融合性能差,针对上述问题本文提出了一种新的基于多分类器的子融合集成分类器系统。该方法考虑在度量层融合层次之上通过对各类基多分类器进行动态选择,票数最多的类别作为融合系统中对特征向量识别的类别,构成一种新的自适应子融合集成分类器方法。实验表明,该方法比传统的分类器以及分类融合方法识别准确率明显更高,具有更好的鲁棒性。     

煤矿井下安全监控分站的设计及其仿真实现

为了设计一种具有低成本、低功耗、易操作、功能强且可靠性高的煤矿井下安全分站,针对煤矿安全生产实际,文章提出了采用MCS-51系列单片机为核心、具有CAN总线通信接口的煤矿井下安全监控分站的设计方案;首先给出煤矿井下安全监控分站的整体构架设计,然后着重阐述模拟量输入信号处理系统的设计过程,最后说明单片机最小系统及其键盘、显示、报警、通信等各个组成部分的设计;为验证设计方案的可行性与有效性,使用Proteus软件对设计内容进行仿真验证,设计的煤矿井下安全监控分站具有瓦斯、温度等模拟量参数超标报警功能和电机开停、风门开闭等开关量指示功能;仿真结果表明:设计的煤矿井下安全监控分站具有一定的实际应用价值.     

Avoiding semantic and temporal gaps in developing software intensive systems

Development of software intensive systems (systems) in practice involves a series of self-contained phases for the lifecycle of a system. Semantic and temporal gaps, which occur among phases and among developer disciplines within and across phases, hinder the ongoing development of a system because of the interdependencies among phases and among disciplines. Such gaps are magnified among systems that are developed at different times by different development teams, which may limit reuse of artifacts of systems development and interoperability among the systems. This article discusses such gaps and a systems development process for avoiding them.     

基于QTE的蒙古文显示机制研究与实现

蒙古语言是中国蒙古族使用的通用语言,由于蒙古文区别于其他文字的书写方式和其自身变形机制等特点,在很多通用的文字处理引擎中都不被支持。在嵌入式产品开发与应用领域中Linux加QTE已经成为流行方式。该文给出了一种在QTE环境上实现基于标准Unicode的蒙古文点阵显示和变形算法, 并自定义了支持蒙古文的QTE组件,扩展了QTE功能,为在Linux加QTE方式的嵌入式体系结构中处理蒙古文提供了一种解决方法。     

Designing economic np control charts: A programmed simulation approach

This paper presents control charts models and the necessary simulation software for the location of economic values of the control parameters. The simulation program is written in FORTRAN, requires only 10K of main storage, and can run on most mini and micro computers. Two models are presented - one describes the process when it is operating at full capacity and the other when the process is operating under capacity. The models allow the product quality to deteriorate to a further level before an existing out-of-control state is detected, and they can also be used in situations where no prior knowledge exists of the out-of-control causes and the resulting proportion defectives.     

基于AD9626的模拟信号采集存储卡设计

自然界的绝大部分信号都是以模拟的形式存在,因此模拟信号的采集转换存储在数字时代十分关键。文章讨论了在雷达信号处理领域基于AD9626的AD采集存储卡的设计原理、硬件结构和程序设计与芯片配置等问题,为今后相关领域的研究提供了可参考的方案。     

The development of robot art

Going through a few examples of robot artists who are recognized worldwide, we try to analyze the deepest meaning of what is called “robot art” and the related art field definition. We also try to highlight its well-marked borders, such as kinetic sculptures, kinetic art, cyber art, and cyberpunk. A brief excursion into the importance of the context, the message, and its semiotics is also provided, case by case, together with a few hints on the history of this discipline in the light of an artistic perspective. Therefore, the aim of this article is to try to summarize the main characteristics that might classify robot art as a unique and innovative discipline, and to track down some of the principles by which a robotic artifact can or cannot be considered an art piece in terms of social, cultural, and strictly artistic interest. This work was presented in part at the 13th International Symposium on Artificial Life and Robotics, Oita, Japan, January 31–February 2, 2008     

A human-computer interface for non-computer specialists

The COM teleconferencing system was designed to be easy to use for both beginners and people with much computer experience. A number of design choices in organizing the human-computer interface were considered very carefully. These design problems are not unique for teleconferencing applications, but will appear in many other developments of human-computer interfaces for non-computer specialists. This report discusses naming conventions, menu format, user commands, help facility and the treatment of ‘type ahead’ from the users.