一种Linux下动态内存泄漏检测技术的实现

内存泄漏是软件开发中经常遇到的问题。在使用C/C 开发的大型软件中,内存泄漏往往很难发现。现介绍了一种基于动态代码插装技术的内存泄漏检测器的实现方法。该方法在实践中证明简单易用,对软件运行期内的影响较低。     

基于模型检测的内存泄露静态测试方法

在C等支持动态内存分配的语言中,指针的使用带来的内存泄露是导致系统性能降低的重要问题.针对现有处理方法的不足,文中设计了一种基于模型检测技术的内存泄露静态检测方法.该方法通过建立基于指针属性的内存泄露漏洞模型,将相应约束断言插桩进源代码,然后利用模型检测工具验证断言的可达性来判断内存泄露.实验结果表明,该方法是有效的和精确的.     

水下管道泄漏检测技术及定位方法研究

为了实时进行水下管道泄漏监测和定位,采用干涉的方法,研制了一种基于Sagnac干涉仪的直线型分布式光纤管道泄漏监测系统。分析了该干涉仪应用于泄漏检测的原理及其泄漏源定位方法,并通过实验研究了管道压力对检测系统的影响。当管道压力大于0.35MPa时,系统的检测效果较佳,且定位误差小于1.17%;压力小于0.35MPa时,无法实现泄漏点定位。结果表明,当管道压力大于0.35MPa时,研制的水下管道泄漏检测系统能有效检测管道泄漏发生,且较准确地确定泄漏源位置。     

多少内存系统性能好

内存是电脑最宝贵的资源,所有的程序只有在内存中才能运行。那么是不是内存越多,系统性能就一定越好呢? 经过实验发现,将内存从16MB增至32MB时,Windows的启动速度和应用程序运行速度大大加快,系统性能有了极大的提高;内存加到64MB时,系统性能进一步提高,但没有前一阶段     

一种新的数字集群通信系统网关内存测试方法

DIMETRA IP系统是一种在广泛的地理区域为无线用户提供语音和数据服务的公共安全的数字集群通信系统。摩托罗拉电话互连网关(MTIG)提供DIMETRA IP系统与外部程控交换机(PABX)之间的语音编码转换,支持对讲机与固定电话或移动电话的通信。这里介绍了进行MTIG内存性能测试的一种创造性的方法,该方法不仅能进行系统级和进程级的内存检测而且支持超长时间的内存测试。测试实践证明,该方法可以提高测试效率,是可行的有益的,值得推广和部署。     

干涉分布式光纤水下长输气管道泄漏检测系统设计

介绍了一种基于马赫曾德尔和萨尼亚克混合干涉仪原理的分布式光纤干涉测量架构,可实时对管道进行泄漏检测和定位。阐述了该架构的检测原理和泄漏点的定位方法,并利用小波变换算法对采集的泄漏信号进行分析处理。对全长为3.994km的感测光纤进行了管道泄漏检测实验并重复做了10次测试实验。实验结果表明,该系统运行稳定且泄漏检测的最大相对定位误差为1.47%。     

密码协议的入侵检测模型设计与实现

文中设计实现了一种在密码执行过程中,检测密码协议上攻击的入侵检测模型,给出了该模型的组成结构,并依据实例,详细介绍了该模型进行入侵检测的原理,及实现入侵检测的方法和步骤,最后使用VC6.0对设计的模型进行了原型系统设计与开发,对使用的主要类及函数进行了详细的说明与介绍,并对该模型的性能进行了分析说明.     

基于策略的Web服务实时性能评价与验证

面向服务的架构(SOA)通过标准Internet协议实现了异构平台上的服务动态集成.然而,开放网络环境的不稳定性和不确定性,给Web服务在线质量评价带来一定的困难.Web服务的测试只能给出测试环境下的服务评价,不能评价服务的真实运行情况,因此服务实时监测对服务运行状态追踪及异常检测具有重要的意义.本文基于服务系统的协同监测,采用原子服务和组合服务多种时间特性定义了Web服务的性能评价模型.在该模型的基础上,提出了一种基于策略的服务在线质量评价与验证方法,给出了基于WS-Policy的策略描述,实现了原型系统,并通过对实验服务的在线监测数据,分析了方法的有效性及性能代价.     

提高内存使用性能十招

内存主要是用来存放各种临时输入输出数据、中间计算结果,以及与外部存储器交换信息。随着软件性能的不断更新、容量不断加大,很多具有大容量内存的电脑在运行大型软件或打开窗口过多时,会严重影响系统的运行性能。下面笔者介绍几种提高内存使用性能的技巧。1.及时释放内存如果长时间使用电脑时发现系统内存不断减少,要注意释放内存。将驻留在内存中的数据从内存中释放出来。释放     

气体泄漏热成像检测系统性能的多指标测试评价系统

目前针对气体泄漏热成像检测系统性能的相关评价技术还不够成熟，相应评价指标的测试系统及其测量方法尚无系统的研究报道。而常规热成像系统的性能评价方法难以直接用于评价气体泄漏热成像检测系统对泄漏气体的探测能力，本文结合泄漏气体特性及各测试系统的特点，设计了一种可测量多类性能指标的气体泄漏热成像检测系统性能的测试评价系统，并以乙烯和甲烷气体为检测目标在实验室环境中分别对NECL、MRGC和MDGC三种评价指标进行了实验测量，结果表明了测试评价系统的可行性和实用性。     

基于邻接点的VMM动态完整性度量方法

对于虚拟机监控器的动态完整性度量,由于其位于特权层,且复杂多变,一直是领域内的研究难点。提出了一种基于邻接点的动态完整性度量方法,利用邻接点作为度量模块的宿主,通过面向内存页的完整性模型和评估算法,实现了动态完整性度量。实验表明,能够准确地检测到完整性受到破坏,且仅对计算密集型任务造成适中的性能损耗。     

VMScan: an out-of-VM malware scanner

The harm caused by malware in cloud computing environment is more and more serious. Traditional anti-virus software is in danger of being attacked when it is deployed in virtual machine on a large scale, and it tends not to be accepted by tenants in terms of performance. In this paper, a method of scanning malicious programs outside the virtual machine is proposed, and the prototype is implemented. This method transforms the memory of the virtual machine to the host machine so that the latter can access it. The user space and kernel space of virtual machine memory are analyzed via semantics, and suspicious processes are scanned by signature database. Experimental results show that malicious programs can be effectively scanned outside the virtual machine, and the performance impact on the virtual machine is low, meeting the needs of tenants.     

A Survey of Adaptive Optimization in Virtual Machines

Virtual machines face significant performance challenges beyond those confronted by traditional static optimizers. First, portable program representations and dynamic language features, such as dynamic class loading, force the deferral of most optimizations until runtime, inducing runtime optimization overhead. Second, modular program representations preclude many forms of whole-program interprocedural optimization. Third, virtual machines incur additional costs for runtime services such as security guarantees and automatic memory management. To address these challenges, vendors have invested considerable resources into adaptive optimization systems in production virtual machines. Today, mainstream virtual machine implementations include substantial infrastructure for online monitoring and profiling, runtime compilation, and feedback-directed optimization. As a result, adaptive optimization has begun to mature as a widespread production-level technology. This paper surveys the evolution and current state of adaptive optimization technology in virtual machines.     

C/C++源代码静态检测系统的设计和实现

为了检测出C/C++源代码程序中常见的运行时错误,设计了一个静态检测系统。该系统通过词法分析、语法分析、语义分析来获取程序的语法树。然后系统的检测程序将会分析语法树的每一个结点,判断结点中的属性信息是否存在错误。创新点在于语法树数据结构和检测程序的设计。通过检测程序对结点的属性值的分析,能够检测出C/C++源代码程序中出现的数组越界、指针错误、字符串函数错误,内存泄露等问题。     

Tubulation techniques for locating fine-leak sites in hermetic electronic packages

Bubble testing is often regarded, at best, as a poor method for locating gross leaks. However, it is demonstrated that, under proper conditions, bubble testing can be used to detect both gross and fine leaks, as well as their precise locations. Although not applicable in all situations, these leak-tests offer rapid and effective methods for identifying leak locations in components that are not adversely affected by the increased differential pressure. This method offers additional advantages such as not being fooled by virtual leaks, and indicating exact leak-location of single or multiple leaks in both the gross and fine leak regimes.     

履带车辆行驶平顺性仿真及试验

基于虚拟样机技术,结合三维造型软件、有限元分析和多体动力学软件,对履带车辆行驶平顺性仿真技术进行了研究.建立履带车辆的刚柔混合虚拟样机模型及随机不平路面模型,生成平顺性仿真模型系统,通过在F等级随机路面行驶仿真,得到车辆行驶时驾驶员座椅位置振动加速度曲线,根据评价标准对车辆进行平顺性评价,并与实车试验测试数据的计算结果进行对比分析.结果表明,仿真模型系统及评价方法合理,可以为提高和改善履带车辆的机动性能提供有效的方法和手段.     

Introduction to Cloud Manufacturing

Cloud manufacturing is a new, networked and intelligent manufacturing model that is service-oriented, knowledge based,high performance, and energy efficient. In this model, state-of-the-art technologies such as informatized manufacturing, cloud computing, Internet of Things, semantic Web, and high-performance computing are integrated in order to provide secure, reliable, and high quality on-demand services at low prices for those involved in the whole manufacturing lifecycle. As an important part of cloud manufacturing, cloud simulation technology based on the COSIM-CSP platform has primarily been applied in the design of a multidisciplinary virtual prototype of a flight vehicle. This lays the foundation for further research into cloud manufacturing.     

智能兴趣热点:一种基于室内虚拟云的移动云计算系统研究（英文）

With network developing and virtualization rising,more and more indoor environment(POIs) such as cafe,library,office,even bus and subway can provide plenty of bandwidth and computing resources.Meanwhile many people daily spending much time in them are still suffering from the mobile device with limited resources.This situation implies a novel local cloud computing paradigm in which mobile device can leverage nearby resources to facilitate task execution.In this paper,we implement a mobile local computing system based on indoor virtual cloud.This system mainly contains three key components:1) As to application,we create a parser to generate the "method call and cost tree" and analyze it to identify resourceintensive methods.2) As to mobile device,we design a self-learning execution controller to make offloading decision at runtime.3) As to cloud,we construct a social scheduling based application-isolation virtual cloud model.The evaluation results demonstrate that our system is effective and efficient by evaluating CPUintensive calculation application.Memoryintensive image translation application and 1/O-intensive image downloading application.     

Evaluation of Static Mapping for Dynamic Space-Shared Multi-task Processing on FPGAs

Whilst FPGAs have been used in cloud ecosystems, it is still extremely challenging to achieve high compute density when mapping heterogeneous multi-tasks on shared resources at runtime. This work addresses this by treating the FPGA resource as a service and employing multi-task processing at the high level, design space exploration and static off-line partitioning in order to allow more efficient mapping of heterogeneous tasks onto the FPGA. In addition, a new, comprehensive runtime functional simulator is used to evaluate the effect of various spatial and temporal constraints on both the existing and new approaches when varying system design parameters. A comprehensive suite of real high performance computing tasks was implemented on a Nallatech 385 FPGA card and show that our approach can provide on average 2.9 × and 2.3 × higher system throughput for compute and mixed intensity tasks, while 0.2 × lower for memory intensive tasks due to external memory access latency and bandwidth limitations. The work has been extended by introducing a novel scheduling scheme to enhance temporal utilization of resources when using the proposed approach. Additional results for large queues of mixed intensity tasks (compute and memory) show that the proposed partitioning and scheduling approach can provide higher than 3 × system speedup over previous schemes.