We are developing a task parallel script language MegaScript for parallel processing on large-scale widely-distributed environments. To achieve high performance, MegaScript requires a scheme that efficiently schedules...
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ISBN:
(纸本)9780889867741
We are developing a task parallel script language MegaScript for parallel processing on large-scale widely-distributed environments. To achieve high performance, MegaScript requires a scheme that efficiently schedules dependent tasks to be executed on a heterogeneous environment. However, the scheduling overhead of existing static schemes are too large while dependency among tasks reduces efficiency of simple dynamic scheduling schemes. Therefore, we propose a combination of multiple schemes to have an efficient hybrid scheduling scheme. To reduce the overhead of static scheduling, we use multi-layered schedulers: the upper layer makes rough global scheduling, and the lower layer makes precise local scheduling. We also incorporate a dynamic scheduler into our scheduler to cope with dynamic change of the system performance. The evaluation using abstract simulation exhibited 6.9-9.8 times speed-up and good scalability, compared to a single level static scheduler.
distributed testing is often hard to implement. This is due to difficulties in handling heterogeneous environments, complex configurations, synchronization, error probing, result maintenance and automation in distribu...
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ISBN:
(纸本)9780889866386
distributed testing is often hard to implement. This is due to difficulties in handling heterogeneous environments, complex configurations, synchronization, error probing, result maintenance and automation in distributed testing. This paper describes a practical testing framework that permits automated distributed testing of distributedsystems and applications. The framework extends the capability of JUnit to support test execution over heterogeneous environments and complex configurations.
Volunteer computing projects use donated CPU time to solve problems that would otherwise be too computationally intensive to solve. The donated CPU time comes from computers whose owners install a volunteer computing ...
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ISBN:
(纸本)9780889867741
Volunteer computing projects use donated CPU time to solve problems that would otherwise be too computationally intensive to solve. The donated CPU time comes from computers whose owners install a volunteer computing client program on their computer, allowing a project to use the computer's idle time. The low participation rate in volunteer computing and the increasing number of volunteer computing projects make improvements that more effectively use the donated CPU cycles very important. Past work showed that using certain task retrieval policies could increase the number of tasks volunteer computing clients complete. However, the past work assumed that the volunteered computers had a single CPU and the task retrieval methods that resulted in more completed tasks required the client to be connected to the Internet more often than the other policies. We simulated the task retrieval policies for computers with multi-core CPUs and found that in most cases, the multi-core architecture can lead to a slightly greater than linear increase in the number of tasks that the clients complete, relative to the number of cores the computer running the client has. Additionally, the multi-core architecture can reduce the performance gap between the best and worst performing policies significantly, affecting which policies are used.
Data replication is a well known solution to provide high data availability in data grid environment. Optimal placement of replica is very important to achieve the maximum possible gains from replication. There is a w...
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ISBN:
(纸本)9780889868786
Data replication is a well known solution to provide high data availability in data grid environment. Optimal placement of replica is very important to achieve the maximum possible gains from replication. There is a wide range of techniques that are available for Replica Placement in data grid environment. Any replication algorithm must answer some very critical questions like;when to create a replica? where to place it? This involves decision making in replication. Bayesian Theorem is a well known statistical method which is currently being used in many disciplines of sciences. In this research Bayesian Theorem is applied in decision making for the optimal Placement of a replica, keeping in view the cost of replication, distance, available bandwidth, and available storage resources to ensure maximum availability of data. It can be applied in the scenarios where decisions have to be made under uncertain conditions. Also it runs in a relatively cost effective way in real time environments. The proposed replication algorithm has a run time complexity of O(n), which shows that presented approach will improve availability, response time, and scalability in data grid environment.
Biological ants organize themselves into forager groups that converge to shortest paths to and from food sources. This has motivated development of a large class of biologically inspired agent-based graph search techn...
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ISBN:
(纸本)9780889868113
Biological ants organize themselves into forager groups that converge to shortest paths to and from food sources. This has motivated development of a large class of biologically inspired agent-based graph search techniques, called Ant Colony Optimization, to solve diverse combinatorial problems. Our approach to parallel graph search uses multiple ant agent populations distributed across processors and clustered computers to solve largescale graph search problems. We discuss our implementation using the NIST Data Flow System II, and show good scalability of our parallel search algorithm.
Cloud computing is one of the most sought after research topics today, with the objective of increasing the potential of a data center's computational resources. Hardware and software virtualization makes the envi...
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Cloud computing is one of the most sought after research topics today, with the objective of increasing the potential of a data center's computational resources. Hardware and software virtualization makes the environment scalable, redundant, and cheaper. This paper proposes a methodology to categorize applications based on workload and hardware utilization. Through this study, a methodology was designed based on the application of instrumentation to capture performance data from computer resources. With this approach, the methodology was applied using two applications with different characteristics (intense CPU bound and high HD write), and the results were then analyzed. One unexpected behavior was encountered in the CPU bound application that required a more thorough investigation.
Modern science requires a close collaboration of scientists who are possibly scattered all over the world. The ongoing spreading of the internet and the emergence of grid and cloud techniques in recent years have caus...
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ISBN:
(纸本)9780889868113
Modern science requires a close collaboration of scientists who are possibly scattered all over the world. The ongoing spreading of the internet and the emergence of grid and cloud techniques in recent years have caused intensified efforts in the development of infrastructures that are suitable to enhance a world-wide collaboration of researchers. The term 'eScience' designates a scientific paradigm which has the primary goal to employ a shared digital infrastructure to improve the collaboration of researchers in the core areas of science. Nevertheless, a mere interconnection of hardware resources, programs, and data would be insufficient to achieve this aim. In this paper we will propose the concept of Shared Workspaces which will simplify the worldwide interdisciplinary collaboration. A platform based on this concept implements a controlled and secure communication, facilitates a connection with high performance computers, and enables the exchange and archiving of programs, data, communications and (intermediate) results. It also allows a connection to legacy projects and repositories.
Emerging scientific and engineering simulations are composed of multiple loosely coupled parallel application components that interact by sharing data at runtime. As a result, coupling and data sharing substrates that...
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ISBN:
(纸本)9780889868786
Emerging scientific and engineering simulations are composed of multiple loosely coupled parallel application components that interact by sharing data at runtime. As a result, coupling and data sharing substrates that can facilitate such data exchange and asynchronous interaction between independent parallel application components, are critical. However, in real-world coupled simulation workflows, data exchange and interaction are dynamic, both in the type of interactions as well as the amount of data exchanged. As a result, the data sharing substrate must handle dynamic and changing coupling/data-exchange requirements from the applications. In this paper, we present the dynamic and adaptive data space(DADS) for coupled simulation workflows. DADS implements a scalable, distributed and dynamic in-memory data space, which is semantically specialized for simulations where data is associated with the discretization of an application domain, e.g., a grid or a mesh. DADS is dynamic in that the data space can be created and deleted at runtime to support dynamically occurring interaction and data exchange. Furthermore, a DADS space can automatically resize itself based on the data exchange requirements as well as the status of the underlying resources. DADS has been implemented and deployed on the Eugene IBM BlueGene/P, and evaluation of its performance on this system is presented.
Recently, cryptanalysts have found collisions on the MD4, MD5, and SHA-0 algorithms;moreover, a method for finding SHA1 collisions with less than the expected calculus complexity has been published. The NIST [1] has t...
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ISBN:
(纸本)9780889868786
Recently, cryptanalysts have found collisions on the MD4, MD5, and SHA-0 algorithms;moreover, a method for finding SHA1 collisions with less than the expected calculus complexity has been published. The NIST [1] has thus decided to develop a new hash algorithm, so called SHA-3, which will be developed through a public competition [3]. From the set of accepted proposals for the further steps of the competition, we have decided to explore the design of an efficient parallel algorithm for the Skein [12] hash function family. The main reason for designing such an algorithm is to obtain optimal performances when dealing with critical applications which require efficiently tuned implementations on multi-core target processors. This preliminary work presents one of the first parallel implementation and associated performance evaluation of Skein available in the literature. To parallelize Skein we have used the tree hash mode in which we create one virtual thread for each node of the tree.
Event Driven Molecular Dynamics (EDMD) simulations is an important tool for simulating particle based real systems. Dependency between events causes coherence and causality problems in parallel EDMD simulations. In th...
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ISBN:
(纸本)9780889869073
Event Driven Molecular Dynamics (EDMD) simulations is an important tool for simulating particle based real systems. Dependency between events causes coherence and causality problems in parallel EDMD simulations. In this paper, we propose a novel parallel EDMD simulation on multi-core architectures. In our method, master-worker strategy is used and a lock-free sorted list structure is implemented as a buffer. We simplify the coherence and causality problems and eliminate most of the locking mechanism. In the algorithm, worker threads get events from an event queue and execute them asynchronously. The results are recorded in the buffer. Master-thread consumes the buffer and then it updates the system state and finally it updates the event queue. Locking mechanism is (still) used to harmonize concurrent access on the event queue. We obtain very promising preliminary experimental results of an ongoing research. On a quad-core computer, speedup of over two times is achieved even for small size systems (32000 molecules).
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