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LCCFS: a lightweight distributed file system for cloud computing without journaling and metadata services

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Science China(Information Sciences) 2019年第7期62卷 142-155页

作者： Li WANG jingling xue Xiangke LIAO Yunchuan WEN Min CHEN School of Computer Science and Technology National University of Defense Technology School of Computer Science and Engineering University of New South Wales

The major usage of a file system integrated with a cloud computing platform is to provide the storage for VM(virtual machine) instances. Distributed file systems, especially those implemented on top of object storage have many potential advantages over traditional local file systems for VM instance storage. In this paper, we make an investigation in the requirements imposed on a file system in cloud computing scenario,and claim that the implementation of a file system for VM instance storage could be reasonably simplified. We demonstrate that on top of an object storage with simple object-granularity transaction support, a lightweight distributed file system, which requires neither journaling nor dedicated metadata services, can be developed for cloud computing. We have implemented such a distributed file system, called LCCFS(lightweight cloud computing file system), based on the RADOS(reliable autonomic distributed object storage) object *** experimental results show that for the main workloads in cloud computing, LCCFS achieves almost the same or slightly higher performance than CephFS(ceph filesystem), another published distributed file system based on RADOS. Compared to CephFS, LCCFS has only one tenth of its LOCs(lines of code). This theoretical simplicity makes it easy to implement LCCFS correctly and stably by avoiding the sheer design and implementation complexity behind CephFS, thereby making LCCFS a promising candidate in the cloud computing production environment.

关键词： cloud computing distributed file system journaling metadata service garbage collection

Enhancement of cooperation between file systems and applications — VFS extensions for optimized performance

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Science China(Information Sciences) 2015年第9期58卷 46-55页

作者： WANG Li LIAO XiangKe xue jingling WEIL Sage WEN YunChuan YANG xueJun School of Computer Science and Technology National University of Defense Technology School of Computer Science and Engineering University of New South Wales

Modern operating systems incorporate an abstract layer called Virtual File System(VFS), which is positioned between user applications and real file systems to hide the differences of various file systems and to expose generic application interfaces for requesting file system services. However, VFS sometimes does not give applications an opportunity to pass information to file systems to help them make correct optimization decisions. In this paper, we review the Linux VFS, discuss its deficiencies and propose several extensions to allow applications to cooperate with the file systems more efficiently. We introduce simple prefetching interfaces and advisory flags to allow applications to communicate application-related semantics to VFS and/or the underlying file systems. These suggestions, which neither affect the semantics of applications nor modify their programming models, not only lead to simple VFS/file systems but also guide them to make correct performance-related decisions, if required. We demonstrate that these interfaces and flags are also easy to implement and can boost application performance by up to 4.29 X.

关键词： virtual file system metadata cache dentry cache page cache page readahead

OpenMC: Towards Simplifying Programming for TianHe Supercomputers

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Journal of Computer Science & Technology 2014年第3期29卷 532-546页

作者：廖湘科杨灿群唐滔易会战王锋吴强薛京灵 School of Computer Science National University of Defense Technology School of Computer Science and Engineering University of New South Wales

Modern petascale and future exascale systems are massively heterogeneous architectures. Developing productive intra-node programming models is crucial toward addressing their programming challenge. We introduce a directive- based intra-node programming model, OpenMC, and show that this new model can achieve ease of programming, high performance, and the degree of portability desired for heterogeneous nodes, especially those in TianHe supercomputers. While existing models are geared towards oifloading computations to accelerators （typically one）, OpenMC alms to more uniformly and adequately exploit the potential offered by multiple CPUs and accelerators in a compute node. OpenMC achieves this by providing a unified abstraction of hardware resources as workers and facilitating the exploitation of asynchronous task parallelism on the workers. We present an overview of OpenMC, a prototyping implementation, and results from some initial comparisons with OpenMP and hand-written code in developing six applications on two types of nodes from TianHe supercomputers.

关键词： supercomputer programming model heterogeneous MIC

Automatic Target Description File Generation

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Journal of Computer Science & Technology 2023年第6期38卷 1339-1355页

作者：耿洪娜吕方钟茗崔慧敏薛景玲冯晓兵 State Key Laboratory of Processors Institute of Computing TechnologyChinese Academy of SciencesBeijing 100190China University of Chinese Academy of Sciences Beijing 100049China School of Computer Science and Engineering University of New South WalesSydneyNSW 2052Australia

Agile hardware design is gaining increasing momentum and bringing new chips in larger quantities to the market ***,it also takes new challenges for compiler developers to retarget existing compilers to these new chips in shorter time than ever ***,retargeting a compiler backend,e.g.,an LLVM backend to a new target,requires compiler developers to write manually a set of target description files(totalling 10300+lines of code(LOC)for RISC-V in LLVM),which is error-prone and *** this paper,we introduce a new approach,Au-tomatic Target Description File Generation(ATG),which accelerates the generation of a compiler backend for a new tar-get by generating its target description files *** a new target,ATG proceeds in two ***,ATG synthesizes a small list of target-specific properties and a list of code-layout templates from the target description files of a set of existing targets with similar instruction set architectures(ISAs).Second,ATG requests compiler developers to fill in the information for each instruction in the new target in tabular form according to the list of target-specific properties syn-thesized and then generates its target description files automatically according to the list of code-layout templates *** first stage can often be reused by different new targets sharing similar *** evaluate ATG using nine RISC-V instruction sets drawn from a total of 1029 instructions in LLVM *** enables compiler developers to gen-erate compiler backends for these ISAs that emit the same assembly code as the existing compiler backends for RISC-V but with significantly less development effort(by specifying each instruction in terms of up to 61 target-specific properties only).

关键词： retargetability compiler target description target backend automatic generator

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左心室厚度的声学超声造影评估效果分析

影像科学与光化学 2020年第2期38卷 313-317页

作者：田苗薛敬玲武汉大学基础医学院湖北武汉443000 宜昌市第二人民医院超声科湖北宜昌443000

本文探究了声学超声造影评估左心室厚度的效果,旨在提高临床测量室壁厚度的准确度。选取2018年1月~2019年5月我院心内科患者94例为研究对象,按照随机数表法将患者分为两组,对照组47例,接受二维超声心动图检测,观察组47例,接受左心声学... 详细信息

本文探究了声学超声造影评估左心室厚度的效果,旨在提高临床测量室壁厚度的准确度。选取2018年1月~2019年5月我院心内科患者94例为研究对象,按照随机数表法将患者分为两组,对照组47例,接受二维超声心动图检测,观察组47例,接受左心声学造影检测。将左心室室壁划分为18节段,比较两组患者检测结果的准确度差异。比较两组患者心尖两腔(A2CH)切面舒张期全部阶段以及收缩期3、6、15、18阶段室壁厚度,差异具有统计学意义(P<0.05);两组患者心尖三腔(A3CH)切面舒张期4、10、13、16阶段以及收缩期4、10、16阶段室壁厚度比较,差异具有统计学意义(P<0.05);两组患者心尖四腔切面(A4CH)切面舒张期5、14、17阶段以及收缩期5、17阶段室壁厚度比较,差异具有统计学意义(P<0.05)。二维超声心动图检测在舒张期1、2、7、8、11节段以及收缩期1、2、7、8、9、11、12、13、14节段的测量结果准确可靠,而左心声学造影检测能提供更为准确的左心室厚度指标,对提高临床对左心室室壁厚度检测的准确度具有重要意义。

关键词：左心室厚度二维超声心动图声学造影

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《逸周书·谥法》时代辨析

西安石油学院学报（社会科学版） 2003年第3期12卷 82-86页

作者：薛金玲西安石油大学档案室陕西西安710065

依据古文献和社会历史发展的规律 ,对《逸周书·谥法》时代进行了辨别、分析和考证 ,最后得出结论 :现存《逸周书·谥法》是春秋初期在周初《谥法》的基础上增益。

关键词：谥法《逸周书·谥法》时代研究

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便携式固体脉冲激光电源研究

激光杂志 2019年第1期40卷 107-111页

作者：薛晶晶初智慧杨小川梁伟长春理工大学理学院长春130022 西南技术物理研究所209所成都610041

随着新型激光装置的不断出现,对激光电源的要求也越来越高,为满足激光电源更加轻量化、小型化的要求,本文提供了一个小型灯泵固体脉冲激光电源的设计和实验结果,其单脉冲输出能量为50 J,频率为20 Hz,做为地照激光器的供电电源。为了减... 详细信息

随着新型激光装置的不断出现,对激光电源的要求也越来越高,为满足激光电源更加轻量化、小型化的要求,本文提供了一个小型灯泵固体脉冲激光电源的设计和实验结果,其单脉冲输出能量为50 J,频率为20 Hz,做为地照激光器的供电电源。为了减小体积和重量,电路设计中采用功率绝缘栅场效应晶体管(VMOS)做开关以及频率为200 k Hz的恒流变换器,变压器中的铁氧磁芯选用PQ40/40,放电电路采用准预燃电路代替通常的预燃电路,控制电路中用晶闸管代替主电继电器,使得整个电源在性能提高的同时,体积变得越来越小,重量也越来越轻。最终所设计完成的小型化电源的整体重量小于3 kg,而且还会将该电源与YAG激光器进行连试并验证其各项性能与指标,使其在变换频率为200 k Hz的情况下工作功率达到1 000 W。

关键词：激光电源恒流变换器准预燃电路小型化

孕期教育联合营养干预对妊娠期糖尿病患者母婴体重及免疫功能的影响

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中国医药导报 2018年第15期15卷 111-114页

作者：朱燕王坚青薛金玲南通大学第四附属医院妇产科江苏盐城224005

目的探讨孕期教育联合营养干预对妊娠期糖尿病(GDM)患者体重增长、免疫功能及新生儿体重功能的影响。方法选择2013年3月~2017年3月南通大学第四附属医院收治的GDM患者96例,根据就诊顺序随机分为对照组(46例)和观察组(50例)。对照组给予... 详细信息

目的探讨孕期教育联合营养干预对妊娠期糖尿病(GDM)患者体重增长、免疫功能及新生儿体重功能的影响。方法选择2013年3月~2017年3月南通大学第四附属医院收治的GDM患者96例,根据就诊顺序随机分为对照组(46例)和观察组(50例)。对照组给予常规产检和教育,观察组在对照组基础上给予孕期综合教育和营养干预。比较两组孕妇体重增长情况、细胞免疫功能及新生儿体重情况。结果观察组患者孕期体重增长[(13.7±2.4)kg]低于对照组[(17.1±2.7)kg],差异有统计学意义(P<0.05);观察组新生儿体重[(3.21±0.71)kg]明显低于对照组[(3.85±0.83)kg],差异有统计学意义(P<0.05);妊娠末期观察组患者的CD3^+、CD4^+及CD4^+/CD8^+水平明显高于对照组,而CD8则明显低于对照组,差异有统计学意义(P<0.05)。结论孕期教育联合营养干预可有效控制GDM患者体重增长,改善细胞免疫功能,并能有效控制新生儿体重。

关键词：孕期教育营养干预妊娠糖尿病母婴结局

口腔黏膜异常增生不同阶段上皮细胞E-cadherin、Twist1启动子甲基化研究

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武汉大学学报（医学版） 2016年第5期37卷 689-693,707页

作者：孙雅楠佘文婷薛敬玲张佳莉陈新明武汉大学口腔医学院湖北武汉430079 口腔基础医学省部共建国家重点实验室培育基地和口腔生物医学教育部重点实验室湖北武汉430079 武汉大学基础医学院湖北武汉430071

目的:研究口腔黏膜异常增生不同阶段上皮细胞E-cadherin及Twist1启动子甲基化,探讨其意义。方法:使用量子点免疫荧光技术检测口腔黏膜异常增生中Twist1的表达。随机选取口腔黏膜上皮异常增生组织,使用甲基化特异性PCR检测其甲基化状态,... 详细信息

目的:研究口腔黏膜异常增生不同阶段上皮细胞E-cadherin及Twist1启动子甲基化,探讨其意义。方法:使用量子点免疫荧光技术检测口腔黏膜异常增生中Twist1的表达。随机选取口腔黏膜上皮异常增生组织,使用甲基化特异性PCR检测其甲基化状态,分别以口腔黏膜单纯过度角化,口腔鳞癌细胞系及口腔鳞癌组织作为阴性或阳性对照。结果:Twist1在口腔黏膜单纯过度角化中几乎不表达,在口腔异常增生黏膜中随上皮异常增生程度加重而升高(P0.05)。结论:Twist1启动子甲基化可能发生在黏膜异常增生早期阶段,且与口腔黏膜上皮癌变过程关系密切。

关键词：口腔黏膜上皮异常增生口腔鳞状细胞癌 E-cadherin Twist1 甲基化