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在基于网格环境的一些网格应用中,用户需要提交一种作业类型,该作业可以被分解为逻辑上独立的元作业,这些元作业不存在依赖和通讯关系,并且它们的执行需要大量的数据移动。针对这种作业类型,本文提出了一种基于流作业的网格调度模型。在该模型中,这些独立的元作业像"流"一样自主地流向各个计算节点去执行,各计算节点接收的流量取决于其计算能力,并避免"断流"问题。同时,该模型还分离了作业流和数据流,实现了作业逻辑控制和数据控制的分离,提高了调度的灵活性。本文将该调度模型应用于药物虚拟筛选应用中,该模型能够充分利用计算节点的计算能力。 相似文献
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针对Hadoop和Spark等大数据分析系统中无先验知识任务的高效执行问题,设计了基于累计工作量(CRW)的任务调度器CRWScheduler。该调度器根据CRW将任务在低权重队列与高权重队列间切换;在为作业分配资源时,同时考虑到作业所在的队列和其瞬时占用资源量,无需作业先验知识即显著提升系统性能。基于Apache Hadoop YARN实现了CRWScheduler原型,在28个节点的基准测试集群上的实验表明,与YARN的公平调度机制相比,作业流时间(JFT)平均降低21%,其中95百分位的作业流时间(JFT)最多降低了35%,并且在与任务级调度程序协作时可获得进一步的性能提升。 相似文献
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一种并发程序依赖性分析方法 总被引:12,自引:0,他引:12
并发程序的依赖性分析是并发程序分析,理解,调试,测试和维护的重要手段,由于并发程序执行的不确定性,目前,尚有很多难点有待解决,针对Ada任务机制,首先提出了一种简洁,有效的并发程序表示方法-并发程序流图,然后讨论了由任务间同步引起的同步依赖和由访问共享变量引起的任务数据依赖,建立了并发程序依赖图,并在此基础上给出了一种有效的并发程序依赖性分析算法,得到一个比较精确的依赖性,较好地解决了并发程序依赖关系不可传递性问题。 相似文献
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在胖节点集群系统中,目前的reservations, backfilling等主流调度算法未能充分考虑单节点过载情况。该文在传统backfilling算法基础上,充分考虑节点当前负载,将预约、回填策略相结合,提出了一种新的LT-backfilling调度算法。设计了基于XML业务流程模板的二层作业调度系统,用户不仅可以提交单个作业,而且可以提交一组具有数据相关性的作业流,使得作业调度系统更加实用化。 LT-backfilling;负载均衡;作业调度;XML;作业流 相似文献
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Dataflow模型的使用,使得大数据计算的批处理和流处理融合为一体.但是,现有的针对大数据计算的集群资源调度框架,要么面向流处理,要么面向批处理,不适合批处理与流处理作业共享集群资源的需求.另外,GPU用于大数据分析计算时,由于缺乏有效的CPU-GPU资源解耦方式,降低了资源使用效率.在分析现有的集群资源调度框架的基础上,设计并实现了一种可以感知批处理/流处理应用的混合式资源调度框架HRM.它以共享状态架构为基础,采用乐观封锁协议和悲观封锁协议相结合的方式,确保流处理作业和批处理作业的不同资源要求.在计算节点上,提供CPU-GPU资源的灵活绑定,采用队列堆叠技术,不但满足流处理作业的实时性需求,也减少了反馈延迟并实现了GPU资源的共享.通过模拟大规模作业的调度,结果显示, HRM的调度延迟只有集中式调度框架的75%左右;使用实际负载测试,批处理与流处理共享集群时,使用HRM调度框架, CPU资源利用率提高25%以上;而使用细粒度作业调度方法,不但GPU利用率提高2倍以上,作业的完成时间也能够减少50%左右. 相似文献
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C程序单元级依赖性分析 总被引:1,自引:1,他引:1
程序依赖性分析是软件分析的一个基本内容,目前的相关工作大多集中在语句级的分析方面。人们同样需要单元级的依赖信息来考察单元间的信息流向及整个程序的构架。本文针对C程序中函数间的调用依赖、参数传递依赖、全局数据依赖以及文件间的包含依赖和外部变量定义依赖进行了分析,并提出单元依赖图表达这些关系。基于此图,本文采用基于信息论的方法度量了单元间的耦合性。单元依赖图中保留的函数调用间的互斥关系提高了度量的准确性。相关的分析思想和技术适用于分析使用其它高级程序设计语言编写的软件。 相似文献
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We study an on-line problem of scheduling parallel jobs on two-dimensional meshes. Parallel jobs arrive dynamically according to the dependencies between them, which are unknown before the jobs appear. Each job may need more than one processor simultaneously and is required to be scheduled on a submesh of the processors which are located on a two-dimensional mesh, i.e., a job must be scheduled on a rectangle of given dimensions. The objective is to minimize the maximum completion time (makespan). We deal with a UET job system, in which all job processing times are equal. We show a lower bound of 3.859 and present a 5.25-competitive algorithm. It significantly improves a previous lower bound of 3.25 and a previous upper bound of 46/7. We consider also the rotated two-dimensional mesh, in which the parallel jobs can be rotated and the rotation of all the jobs is feasible. A lower bound of 3.535 is proven and an on-line algorithm with competitive ratio of at most 4.25 is derived. 相似文献
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XML是因特网中不同企业之间进行信息交流的一种标准的数据转换模式,为了加速数据之间的转换,企业组织通过定义公共数据文档接口来实现基于XML的应用。本文提出了一种新的将关系数据模式转换为XML模式的方法。在转换的过程中,不仅考虑关系模式的结构,而且考虑语义约束,比如内部函数依赖。该方法的输入模式是具有多值函数依赖的关系模式,输出模式是X-Schema。最后,通过实验对该转换方法进行了验证。 相似文献
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Gyrd Brændeland Author Vitae Atle Refsdal Author Vitae Author Vitae 《Journal of Systems and Software》2010,83(10):1995-2013
The risk analysis of critical infrastructures such as the electric power supply or telecommunications is complicated by the fact that such infrastructures are mutually dependent. We propose a modular approach to the modelling and analysis of risk scenarios with dependencies. Our approach may be used to deduce the risk level of an overall system from previous risk analyses of its constituent systems. A custom made assumption-guarantee style is put forward as a means to describe risk scenarios with external dependencies. We also define a set of deduction rules facilitating various kinds of reasoning, including the analysis of mutual dependencies between risk scenarios expressed in the assumption-guarantee style. 相似文献
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Discovering branching and fractional dependencies in databases 总被引:1,自引:1,他引:0
The discovery of dependencies between attributes in databases is an important problem in data mining, and can be applied to facilitate future decision-making. In the present paper some properties of the branching dependencies are examined. We define a minimal branching dependency and we propose an algorithm for finding all minimal branching dependencies between a given set of attributes and a given attribute in a relation of a database. Our examination of the branching dependencies is motivated by their application in a database storing realized sales of products. For example, finding out that arbitrary p products have totally attracted at most q new users can prove to be crucial in supporting the decision making.In addition, we also consider the fractional and the fractional branching dependencies. Some properties of these dependencies are examined. An algorithm for finding all fractional dependencies between a given set of attributes and a given attribute in a database relation is proposed. We examine the general case of an arbitrary relation, as well as a particular case where the problem of discovering the fractional dependencies is considerably simplified. 相似文献
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弹性数据相关与软件流水 总被引:1,自引:0,他引:1
最差路径是有分支循环软件流水的一大障碍.对于有分支循环,某些数据相关(称为弹性相关)在循环的动态执行中可能产生、也可能不产生实例.据此,可将严重限制并行性的弹性相关用限制较松的虚构相关代替,再进行软件流水.若调度没有遵守原来的弹性相关,则使用下推变换修正.从而缓解或者完全解除了最差路径的限制.该方法与经典的控制猜测互补,特点是允许调度含错,然后纠错. 相似文献
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The frequent and volatile unavailability of volunteer-based Grid computing resources challenges Grid schedulers to make effective
job placements. The manner in which host resources become unavailable will have different effects on different jobs, depending
on their runtime and their ability to be checkpointed or replicated. A multi-state availability model can help improve scheduling
performance by capturing the various ways a resource may be available or unavailable to the Grid. This paper uses a multi-state
model and analyzes a machine availability trace in terms of that model. Several prediction techniques then forecast resource
transitions into the model’s states. We analyze the accuracy of our predictors, which outperform existing approaches. We also
propose and study several classes of schedulers that utilize the predictions, and a method for combining scheduling factors.
We characterize the inherent tradeoff between job makespan and the number of evictions due to failure, and demonstrate how
our schedulers can navigate this tradeoff under various scenarios. Lastly, we propose job replication techniques, which our
schedulers utilize to replicate those jobs that are most likely to fail. Our replication strategies outperform others, as
measured by improved makespan and fewer redundant operations. In particular, we define a new metric for replication efficiency,
and demonstrate that our multi-state availability predictor can provide information that allows our schedulers to be more
efficient than others that blindly replicate all jobs or some static percentage of jobs. 相似文献
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Edward A Patrick 《Pattern recognition》1990,23(12):1427-1439
A new classification method called The Outcome Advisor® (OA) is presented which is an outgrowth of statistical pattern recognition and the Patrick-Fischer Generalized K-nearest Neighbor Decision Rule. Involved are new definitions of relative frequency and correlation. Training examples are store and processing begins once findings (a focus) are presented. An almost unlimited number of inferences can be made as an inference system and any feature can be used to define categories as a classification system. Implementable as a new neural net structure which is distribution free, multi-dimensional dependencies in the feature space for each category are learned utilizing a new definition of relative frequency. The new method may help explain how certain neural net structures may be estimating multidimensional dependencies. The OA has been trained and tested on established data bases and has improved performance as measured by experimental probability of error. 相似文献
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随着现代互联网数据中心的规模越来越大,数据中心面临着能耗、可靠性、可管理性与可扩展性等方面的挑战。同时,数据中心承载的服务多样,既有在线Web服务,也有离线批处理任务。在线任务要求较低的延迟,而离线任务要求较高的吞吐量。为了提高服务器利用率,降低数据中心能耗,当前数据中心往往将在线任务和离线任务混合部署到同一个计算集群中。在混部场景下,如何同时满足在线和离线任务的不同要求,是目前面临的关键挑战。分析了阿里巴巴于2018年发布的含有4034台服务器的混部计算集群在8天内的日志数据(cluster-trace-v2018),从静态配置信息、动态混部运行状态、离线批处理作业DAG依赖结构等出发,揭示其负载特征,包括任务倾斜与容器部署的相关关系等,根据任务依赖关系与关键路径,提出了相应的任务调度优化策略。 相似文献
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Transactional dependencies play an important role in coordinating and executing the subtransactions in advanced transaction
processing models, such as, nested transactions and workflow transactions. Researchers have formalized the notion of transactional
dependencies and have shown how various advanced transaction models can be expressed using different kinds of dependencies.
Incorrect specification of dependencies can result in unpredictable behavior of the advanced transaction, which, in turn,
can lead to unavailability of resources and information integrity problems. In this work, we focus on how to correctly specify
dependencies in an advanced transaction. We enumerate the different kinds of dependencies that may be present in an advanced
transaction and classify them into two broad categories: event ordering and event enforcement dependencies. Different event
ordering and event enforcement dependencies in an advanced transaction often interact in subtle ways resulting in conflicts
and redundancies. We describe the different types of conflicts that can arise due to the presence of multiple dependencies
and describe how one can detect such conflicts. An advanced transaction may also contain redundant dependencies—these are
dependencies that can be logically derived from other dependencies. We show how such extraneous dependencies can be eliminated
to get an equivalent set of dependencies that has the same effect as the original set. Our dependency analysis is done in
the context of a generalized advanced transaction model that is capable of expressing different kinds of advanced transactions.
Recommended by: Amit Sheth 相似文献
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In this paper, we address a parallel machine scheduling problem to minimize the total weighted completion time, where product families are involved. Major setups occur when processing jobs of different families, and sequence dependencies are also taken into account. Considering its high practical relevance, we focus on the special case where all jobs of the same family have identical processing times. In order to avoid redundant setups, batching jobs of the same family can be performed. We first develop a variable neighborhood search algorithm (VNS) to solve the interrelated subproblems in a simultaneous manner. To further reduce computing time, we also propose an iterative scheme which alternates between a specific heuristic to form batches and a VNS scheme to schedule entire batches. Computational experiments are conducted which confirm the benefits of batching. Test results also show that both simultaneous and iterative approach outperform heuristics based on a fixed batch size and list scheduling. Furthermore, the iterative procedure succeeds in balancing solution quality and computing time. 相似文献