自适应调整虚拟机权重参数的调度方法

在基于特权服务操作系统的虚拟机架构下客户操作系统需要借助特权服务操作系统来访问真实硬件,目前虚拟机调度算法的优化主要是侧重于I/O密集型虚拟机的研究,而忽视了CPU密集型虚拟机,更忽视了特权服务操作系统的I/O处理能力对虚拟机整体性能的影响.针对这些问题,提出了一种基于Credit算法的自适应调整虚拟机权重参数的优化调度方法,将特权服务操作系统的I/O处理能力作为虚拟机参数调整的一个重要参数,同时兼顾I/O密集型虚拟机和CPU密集型虚拟机对资源的需求.实验结果表明该方法能够及时根据当前的I/O请求数量和特权服务操作系统的处理能力合理调整虚拟机的权重参数,从而大大提高了客户操作系统CPU处理性能和硬件设备的访问性能.     

对延迟敏感型应用的虚拟机调度算法

针对Credit调度算法不能保证实时性的不足提出两点改进。首先,当有大量I/O任务时对BOOST态虚拟CPU进行负载均衡来缩短系统响应时间。其次,利用动态时间片代替原来的固定时间片去适应虚拟CPU的动态变化。通过检测系统对任务的平均响应时间和周转时间来评估改进前和改进后对I/O任务的响应的影响。实验研究表明,改进之后的Credit调度算法平均响应时间与改进前相比降低了102.3%,可以显著提高I/O延迟敏感型应用的性能。     

异构云环境下基于分簇的云资源感知任务调度方案

针对提高异构云平台中资源调度的效率,提出了一种基于任务和资源分簇的异构云计算平台任务调度方案。利用K-means算法,根据任务的CPU和I/O处理时间对任务分簇,根据资源的计算能力对资源分簇;然后,将任务簇对应到合适的资源簇,并利用最早截止时间优先（EDF）算法对任务簇中的独立任务进行调度,利用提出的改进型最小关键路径（MCP）算法对依赖性任务进行调度。实验结果表明,在资源异构的云计算环境中,该方案执行任务时间短、能耗低。     

RAID控制器中I/O调度算法研究

介绍应用于RAID控制器的I/O调度算法的设计与实现.主要目标是把来自RAID模块针对每个磁盘的具体读写请求按照响应的策略放入对应磁盘的读写I/O队列.然后根据具体请求的优先级和读写特性,对响应请求在队列中的次序进行调整或者对前后项进行合并,实现I/O请求的调度策略.     

面向云存储的I/O资源效用优化调度算法研究

随着云计算的普及,越来越多的客户选择使用基于云的服务,以避免冗余的设施购买费用和繁杂的系统设计与维护,从而将精力集中在自己的专业领域.通常,云服务的客户从云服务供应商购买虚拟机,并根据双方商定达成的服务水平目标(service level objective,SLO)约束购买到的计算资源.分布式存储中大量的文件分布在不同的存储节点上,现有的CPU、内存以及带宽等资源的分配调度算法并不适用磁盘I/O资源.从云服务提供商的角度来说,高效用的I/O资源调度算法有利于提高其系统的利用率,节约资源开销并增加企业收益率.从云存储提供商为获取高效率高收益率的角度考虑,通过对用户的虚拟机在不同存储节点上的访问特性建模,提出了一个新的自适应分布式I/O资源调度算法,简称为PC算法.PC算法能够:1)根据用户与服务商之间制定的SLO,动态地在各个存储节点中为每个虚拟机制定适当的局部SLO,满足虚拟机对个体节点的访问需求;2)为各虚拟机提供高效健壮的资源分配策略,既能尽可能利用I/O资源,又避免由无序的I/O资源竞争导致的虚拟机I/O资源饥饿.PC算法能够根据不同的I/O资源供应状况在两种调度策略间自动切换,当系统I/O资源充足时,算法采用最早截止时间优先算法(earliest deadline first,EDF)方式提高I/O资源使用率;反之则根据每个I/O请求的预计效益来提高总收益率.实验结果表明,在不采用预先设定虚拟机对各个节点访问量的前提下,PC算法能根据访问模式制定合理的资源分配,提高系统的I/O资源利用率和收益.     

一种灵活高效的虚拟CPU调度算法

目前,虚拟化已经广泛应用于数据中心,但主流的虚拟CPU调度策略并没有实现对I/O性能的保障,尤其当延时敏感型负载的虚拟机和计算敏感型负载的虚拟机竞争CPU资源时,其性能显著下降.针对上述问题,本文提出了一种灵活、高效的虚拟CPU调度算法（FLMS）.FLMS通过采用虚拟机分类、虚拟CPU绑定、多类时间片等技术降低了虚拟机的响应延时,同时基于多处理器架构重新设计了负载均衡策略,优化了虚拟CPU迁移.FLMS通用于目前主流的虚拟化方案,在软件虚拟化方式下相比于最新的优化方案延时降低了30%,带宽有10%的提升;在使用硬件辅助虚拟化的系统中,通过FLMS能够获得接近原生系统的I/O性能,并且保证了整个系统的公平性.     

基于混合GA算法的工作流作业调度队列优化

工作流作业的调度效率是评价工作流管理系统整体表现的重要指标。众所周知,工作流作业的调度问题是一个NP-hard问题,而异构的计算环境使得问题更加棘手。分层基因算法LGA将启发式算法与GA算法相结合,利用GA算法来优化经过正向分层之后的工作流作业调度队列,显著地减少了工作流作业的执行时间。该算法根据作业的分层优先级来产生作业队列,把队列中的同层作业从整体上看作是一位基因来处理,有效地对算法的进化方向进行规划,并通过对杂交和变异流程的改进,增强算法的搜索深度和广度。实验表明,相比于其他混合GA算法,经LGA算法优化之后的工作流作业调度队列,所需的执行时间更少。     

一种云计算环境下基于Xen的虚拟机调度机制

目前Xen下的经典的虚拟机调度算法忽略了服务操作系统的I/O处理能力对系统整体性能的影响,同时未考虑增加延迟敏感型任务的响应速度,为此,设计了一种云计算环境下的改进的Credit调度算法;首先,设计了一种新的Credit值自适应计算方法,然后设计了一种根据服务操作系统的请求处理速度来确定各虚拟客户操作系统和服务操作系统CPU物理时间片的权值确定方法并描述了权值更新时机,最后,对改进的VCPU调度算法进行了定义和描述,在算法中通过优先考虑延迟敏感任务和缓存关联任务作为下一步调度的VCPU以进一步提高算法性能;实验结果表明:文中方法有效实现Xen框架下的虚拟CPU调度,较其它方法相比,将CPU利用率提高了8%以上,是一种有效的适用于云计算的虚拟机调度方法,具有很强的可行性。     

一种实时性O(1)调度改进算法*

实时进程调度算法在任务调度过程中对于公平性体现不够。为了解决这个问题,在Linux 2.6.11内核的基础上作了改进,提出了一个兼具公平性和实时性的RMOSA(realtime modified O(1) scheduling algorithm)算法。保留了I/O队列以缩短I/O请求的响应时间,同时采用动态计算优先级和时间片的方法来使通用进程调度达到最优。最后,通过仿真实验的结果比较,证明了RMOSA算法相对于Linux 2.6.11O(1)调度算法的优越性。     

基于Backfilling调度算法的“扩履适足”改进算法

在众多的并行作业调度算法中,Backfilling通常被广泛认为是有效提高CPU利用率的一种算法。该算法是在FCFS算法的基础上,将队列中较小的作业回填（Backfill）到空闲 CPU,以提高CPU利用率。但是,当空闲CPU数量仍然无法满足Backfilling算法中小作业的回填要求时,系统仍有部分CPU闲置,因而也难以达到更好地提高CPU利用率的目的。 。对于共享内存体系结构的并行计算机系统,本文提出了基于Backfilling算法的“扩履适足”的改进算法。该算法以正在运行的作业的CPU利用率为依据,通过动态调整正在运行作业的CPU数,扩大可供回填（backfill）的CPU空间,使得Backfilling算法无法回填的作业得到运行,弥补了Backfilling算法的不足,大大提高了共享内存体系结构并
并行计算机系统的CPU利用率。     

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。     

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.     

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.     

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     

Explanation and prediction: an architecture for default and abductive reasoning

Although there are many arguments that logic is an appropriate tool for artificial intelligence, there has been a perceived problem with the monotonicity of classical logic. This paper elaborates on the idea that reasoning should be viewed as theory formation where logic tells us the consequences of our assumptions. The two activities of predicting what is expected to be true and explaining observations are considered in a simple theory formation framework. Properties of each activity are discussed, along with a number of proposals as to what should be predicted or accepted as reasonable explanations. An architecture is proposed to combine explanation and prediction into one coherent framework. Algorithms used to implement the system as well as examples from a running implementation are given.     

Three Process Perspectives: Organizations, Teams, and People

This paper provides the author's personal views and perspectives on software process improvement. Starting with his first work on technology assessment in IBM over 20 years ago, Watts Humphrey describes the process improvement work he has been directly involved in. This includes the development of the early process assessment methods, the original design of the CMM, and the introduction of the Personal Software Process (PSP)^SM and Team Software Process (TSP){^SM}. In addition to describing the original motivation for this work, the author also reviews many of the problems he and his associates encountered and why they solved them the way they did. He also comments on the outstanding issues and likely directions for future work. Finally, this work has built on the experiences and contributions of many people. Mr. Humphrey only describes work that he was personally involved in and he names many of the key contributors. However, so many people have been involved in this work that a full list of the important participants would be impractical.     

基于复小波噪声方差显著修正的SAR图像去噪

提出了一种基于复小波域统计建模与噪声方差估计显著性修正相结合的合成孔径雷达(Synthetic Aperture Radar,SAR)图像斑点噪声滤波方法。该方法首先通过对数变换将乘性噪声模型转化为加性噪声模型,然后对变换后的图像进行双树复小波变换(Dualtree Complex Wavelet Transform,DCWT),并对复数小波系数的统计分布进行建模。在此先验分布的基础上,通过运用贝叶斯估计方法从含噪系数中恢复原始系数,达到滤除噪声的目的。实验结果表明该方法在去除噪声的同时保留了图像的细节信息,取得了很好的降噪效果。     

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。