A GPU-Accelerated In-Memory Metadata Management Scheme for Large-Scale Parallel File Systems

Driven by the increasing requirements of high-performance computing applications,supercomputers are prone to containing more and more computing nodes.Applications running on such a large-scale computing system are likely to spawn millions of parallel processes,which usually generate a burst of I/O requests,introducing a great challenge into the metadata management of underlying parallel file systems.The traditional method used to overcome such a challenge is adopting multiple metadata servers in the scale-out manner,which will inevitably confront with serious network and consistence problems.This work instead pursues to enhance the metadata performance in the scale-up manner.Specifically,we propose to improve the performance of each individual metadata server by employing GPU to handle metadata requests in parallel.Our proposal designs a novel metadata server architecture,which employs CPU to interact with file system clients,while offloading the computing tasks about metadata into GPU.To take full advantages of the parallelism existing in GPU,we redesign the in-memory data structure for the name space of file systems.The new data structure can perfectly fit to the memory architecture of GPU,and thus helps to exploit the large number of parallel threads within GPU to serve the bursty metadata requests concurrently.We implement a prototype based on BeeGFS and conduct extensive experiments to evaluate our proposal,and the experimental results demonstrate that our GPU-based solution outperforms the CPU-based scheme by more than 50％under typical metadata operations.The superiority is strengthened further on high concurrent scenarios,e.g.,the high-performance computing systems supporting millions of parallel threads.     

基于压缩感知的鲁棒性人脸表情识别

为了有效提高噪声背景下的人脸表情识别性能,提出一种基于压缩感知的鲁棒性人脸表情识别方法.先通过对腐蚀的测试样本表情图像进行稀疏表示,再利用压缩感知理论寻求其最稀疏的解,然后采用求得的最稀疏解信息实现人脸表情的分类.在标准的Cohn-Kanade表情数据库的实验测试结果表明,该方法取得的人脸表情识别性能优于最近邻法、支持向量机以及最近邻子空间法.可见,该方法用于人脸表情识别,识别效果较好,鲁棒性较高.     

Karamanlidika Digital Library Proposal: Reconstructing the Past of a Specific Diaspora

ABSTRACT

The World Wide Web provides unlimited visibility for the personal documents and cultural artifacts that remain in the hands of families of people belonging to different diasporas. Computer mediated platforms are often the building blocks of their transcendental homelands. This article presents a study aiming to build a model and community around Karamanlides by using digital library technologies. Karamanlides is one of the many interesting communities in need of the creation of a “niche personal/community knowledge environment” as an archetype for similar conceptualizations.     

Toward a Conceptual Emulation Framework for the Preservation of Archaeological 3D Visualizations

Through the Preservation of Complex Objects Symposia (POCOS), leading researchers and practitioners have managed to propose strategies for preserving digital art and computer games. The same is not true for the preservation of archaeological visualizations. This article therefore discusses the following question: “Can emulation be employed to effectively preserve obsolete computer visualizations from the Archaeology domain?” Guidelines and test results coming from this work would be of great benefit to the archaeological community, and would contribute knowledge to other research communities, specifically those interested in similar data types/3D visualizations.     

QMDS: a file system metadata management service supporting a graph data model-based query language

File system metadata management has become a bottleneck for many data-intensive applications that rely on high-performance file systems. Part of the bottleneck is due to the limitations of an almost 50-year-old interface standard with metadata abstractions that were designed at a time when high-end file systems managed less than 100 MB. Today's high-performance file systems store 7–9 orders of magnitude more data, resulting in a number of data items for which these metadata abstractions are inadequate, such as directory hierarchies unable to handle complex relationships among data. Users of file systems have attempted to work around these inadequacies by moving application-specific metadata management to relational databases to make metadata searchable. Splitting file system metadata management into two separate systems introduces inefficiencies and systems management problems. To address this problem, we propose QMDS: a file system metadata management service that integrates all file system metadata and uses a graph data model with attributes on nodes and edges. Our service uses a query language interface for file identification and attribute retrieval. We present our metadata management service design and architecture and study its performance using a text analysis benchmark application. Results from our QMDS prototype show the effectiveness of this approach. Compared to the use of a file system and relational database, the QMDS prototype shows superior performance for both ingest and query workloads.     

Herding Cats

Abstract

With the rapid growth in the number of electronic resources available via the Internet, a variety of methods have been developed to organize and access these objects. Librarians, scholars, and computing engineers have each applied their own techniques to the process. This article examines the strengths and weaknesses of organizational systems developed by each group. The appropriateness of including remotely accessed electronic resources as part of a library collection is discussed, and the success of traditional cataloging methods and structures for describing remote electronic resources is examined. These traditional cataloging techniques are compared to other methods for describing, organizing, and accessing electronic documents such as TEI headers, browsing lists, and robot generated search indexes. For Metacatalogs of the future to be successful tools for organizing and accessing all information, methods must be developed to utilize all existing organizational tools by layering, exchanging, and translating data within a loosely-coupled organizational system.     

基于访问控制的动态着色技术在攻击检测中的研究

内存腐烂攻击在软件安全攻击中占据着较大的比重。近来,动态着色技术得到了越来越多的关注,这种技术通过在访问内存时检测指针的完整性来抵御攻击。然而,存在一类可以绕过指针完整性检查的策略来进行攻击的实例,比如数组的越界访问攻击。提出了一种基于动态着色跟踪分析的方法来解决这类已有着色技术不能检测的问题。其思想是,借助于内存访问控制的思路,首先像已有的动态着色技术那样,在内存访问时对指针进行完整性检查,然后检查指针将要访问的内存区域是否处于指针合理的访问范围之内。原型系统是基于Valgrind的,并不需要源码,因此可以用于很多商业软件。初步实验验证结果表明,该方法可以有效地检测出很多类型的攻击,系统的性能损耗接近于Memcheck这种常用的内存错误检测工具。     

数据仓库建模和设计的最新进展

从概念建模、逻辑建模、设计方法、互操作性和元数据4个方面综述了现阶段数据仓库的研究内容,分析了数据仓库的研究现状,指出了数据仓库新的应用前景和面临的挑战,以指导数据仓库的进一步研究。     

网络中心环境下基于信息超市的数据共享

数据共享是信息资源管理的核心内容。传统"点到点"数据共享方式存在如下缺陷:增加新的应用时就要建立该应用系统到已经存在的应用系统之间的连接,在不同的应用系统进行升级或接口发生变化时会遇到很多的麻烦,至少需要重新修改不同应用系统之间的连接,这导致其缺乏灵活性。本文针对上述缺陷提出了基于信息超市的数据共享方式。该方式使得新的信息资源能动态地加入并且不需要修改系统间的接口。