| 1. |
- Asplund, Mikael, et al.
(författare)
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Middleware extensions that trade consistency for availability
- 2009
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Ingår i: CONCURRENCY AND COMPUTATION-PRACTICE and EXPERIENCE. - : John Wiley & Sons. - 1532-0626 .- 1532-0634. ; 21:9, s. 1181-1203
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Tidskriftsartikel (refereegranskat)abstract
- Replicated distributed object systems are deployed to provide timely and reliable services to actors at distributed locations. This paper treats applications in which data updates are dependent on satisfaction of integrity constraints over multiple objects. Network partitions, caused by occasional link failures, overload or attacks create problems in keeping both consistency and availability in such networks. We propose a means of achieving higher availability by providing partition-awareness in middleware. The general approach has been illustrated by implementing a number of CORBA extensions that trade consistency for availability during network partitions. This paper contains a thorough experimental evaluation that presents the gains and costs of our approach. The experiments clearly illustrate the benefit of our protocols in terms of significantly higher availability and the number of performed operations.
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| 2. |
- Bergman, Sara, et al.
(författare)
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Permissioned Blockchains and Distributed Databases : A Performance Study
- 2020
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Ingår i: Concurrency and Computation. - : John Wiley & Sons. - 1532-0626 .- 1532-0634. ; 32:12
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Tidskriftsartikel (refereegranskat)abstract
- Blockchains are increasingly studied in the context of new applications. Permissioned blockchains promise to deal with the issue of complete removal of trust, a notion that is currently the hallmark of the developed society. Before the idea is adopted in contexts where resource efficiency and fast operation is a requirement, one could legitimately ask the question: can permissioned blockchains match the performance of traditional large‐scale databases? This paper compares two popular frameworks, Hyperledger Fabric and Apache Cassandra, as representatives of permissioned blockchains and distributed databases, respectively. We compare their latency for varying workloads and network sizes. The results show that, for small systems, blockchains can start to compete with traditional databases, but also that the difference in consistency models and differences in setup can have a large impact on the resulting performance.
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| 3. |
- Brandic, Ivona, et al.
(författare)
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Specification, Planning, and Execution of QoS-awareGrid Workflows within the Amadeus Environment
- 2008
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Ingår i: Concurrency and Computation. - : John Wiley & Sons. - 1532-0626 .- 1532-0634. ; 20:4, s. 331-345
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Tidskriftsartikel (refereegranskat)abstract
- Commonly, at a high level of abstraction Grid applications are specified based on the workflow paradigm. However, majority of Grid workflow systems either do not support Quality of Service (QoS), or provide only partial QoS support for certain phases of the workflow lifecycle. In this paper we present Amadeus, which is a holistic service-oriented environment for QoS-aware Grid workflows. Amadeus considers user requirements, in terms of QoS constraints, during workflow specification, planning, and execution. Within the Amadeus environment workflows and the associated QoS constraints are specified at a high level using an intuitive graphical notation. A distinguishing feature of our system is the support of a comprehensive set of QoS requirements, which considers in addition to performance and economical aspects also legal and security aspects. A set of QoS-aware service-oriented components is provided for workflow planning to support automatic constraint-based service negotiation and workflow optimization. For improving the efficiency of workflow planning we introduce a QoS-aware workflow reduction technique. Furthermore, we present our static and dynamic planning strategies for workflow execution in accordance with user-specified requirements. For each phase of the workflow lifecycle we experimentally evaluate the corresponding Amadeus components.
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| 4. |
- Casalicchio, Emiliano, et al.
(författare)
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The state-of-the-art in container technologies : Application, orchestration and security
- 2020
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Ingår i: Concurrency and Computation. - : John Wiley and Sons Ltd. - 1532-0626 .- 1532-0634. ; 32:17
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Tidskriftsartikel (refereegranskat)abstract
- Containerization is a lightweight virtualization technology enabling the deployment and execution of distributed applications on cloud, edge/fog, and Internet-of-Things platforms. Container technologies are evolving at the speed of light, and there are many open research challenges. In this paper, an extensive literature review is presented that identifies the challenges related to the adoption of container technologies in High Performance Computing, Big Data analytics, and geo-distributed (Edge, Fog, Internet-of-Things) applications. From our study, it emerges that performance, orchestration, and cyber-security are the main issues. For each challenge, the state-of-the-art solutions are then analyzed. Performance is related to the assessment of the performance footprint of containers and comparison with the footprint of virtual machines and bare metal deployments, the monitoring, the performance prediction, the I/O throughput improvement. Orchestration is related to the selection, the deployment, and the dynamic control of the configuration of multi-container packaged applications on distributed platforms. The focus of this work is on run-time adaptation. Cyber-security is about container isolation, confidentiality of containerized data, and network security. From the analysis of 97 papers, it came out that the state-of-the-art is more mature in the area of performance evaluation and run-time adaptation rather than in security solutions. However, the main unsolved challenges are I/O throughput optimization, performance prediction, multilayer monitoring, isolation, and data confidentiality (at rest and in transit). © 2020 John Wiley & Sons, Ltd.
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| 5. |
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| 6. |
- Edmundsson, Niklas, et al.
(författare)
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Design and Evaluation of a TOP100 Linux Super Cluster System
- 2004
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Ingår i: Concurrency and Computation: Practice & Experiences. - : John Wiley & Sons, Inc.. - 1532-0634 .- 1532-0626. ; 16:8, s. 735-750
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Tidskriftsartikel (refereegranskat)abstract
- The High Performance Computing Center North (HPC2N) Super Cluster is a truly self-made high-performance Linux cluster with 240 AMD processors in 120 dual nodes, interconnected with a high-bandwidth, low-latency SCI network. This contribution describes the hardware selected for the system, the work needed to build it, important software issues and an extensive performance analysis. The performance is evaluated using a number of state-of-the-art benchmarks and software, including STREAM, Pallas MPI, the Atlas DGEMM, High-Performance Linpack and NAS Parallel benchmarks. Using these benchmarks we first determine the raw memory bandwidth and network characteristics; the practical peak performance of a single CPU, a single dual-node and the complete 240-processor system; and investigate the parallel performance for non-optimized dusty-deck Fortran applications. In summary, this $500 000 system is extremely cost-effective and shows the performance one would expect of a large-scale supercomputing system with distributed memory architecture. According to the TOP500 list of June 2002, this cluster was the 94th fastest computer in the world. It is now fully operational and stable as the main computing facility at HPC2N. The system’s utilization figures exceed 90%, i.e. all 240 processors are on average utilized over 90% of the time, 24 hours a day, seven days a week.
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| 7. |
- Elmroth, Erik, 1964-, et al.
(författare)
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A standards-based Grid resource brokering service supporting advance reservations, coallocation and cross-Grid interoperability
- 2009
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Ingår i: Concurrency and Computation. - : Wiley. - 1532-0626 .- 1532-0634. ; 21:18, s. 2298-2335
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Tidskriftsartikel (refereegranskat)abstract
- The problem of Grid-middleware interoperability is addressed by the design and analysis of a feature-rich, standards-based framework for all-to-all cross-middleware job submission.The architecture is designed with focus on generality and flexibility and builds on extensive use, internally and externally, of (proposed) Web and Grid services standards such asWSRF, JSDL, GLUE, and WS-Agreement. The external use providesthe foundation for easy integration into specific middlewares,which is performed by the design of a small set of plugins for each middleware. Currently, plugins are provided for integrationinto Globus Toolkit 4 and NorduGrid/ARC. The internal use of standard formats facilitates customizationof the job submission service by replacement of custom components for performing specific well-defined tasks.Most importantly, this enables the easy replacement of resource selection algorithms by algorithms that addresses the specific needs of a particular Grid environment and job submission scenario.By default, the service implements a decentralized brokering policy, strivingto optimize the performance for the individual user by minimizing the response time for each job submitted. The algorithms in our implementation perform resource selectionbased on performance predictions, and provide support for advance reservations as well as coallocation of multiple resources for coordinated use.The performance of the system is analyzed with focuson overall service throughput (up to over 250 jobs per minute)and individual job submission response time (down to under one second).
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| 8. |
- Ernstsson, August, et al.
(författare)
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Extending smart containers for data locality-aware skeleton programming
- 2019
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Ingår i: Concurrency and Computation. - : WILEY. - 1532-0626 .- 1532-0634. ; 31:5
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Tidskriftsartikel (refereegranskat)abstract
- We present an extension for the SkePU skeleton programming framework to improve the performance of sequences of transformations on smart containers. By using lazy evaluation, SkePU records skeleton invocations and dependencies as directed by smart container operands. When a partial result is required by a different part of the program, the run-time system will process the entire lineage of skeleton invocations; tiling is applied to keep chunks of container data in the working set for the whole sequence of transformations. The approach is inspired by big data frameworks operating on large clusters where good data locality is crucial. We also consider benefits other than data locality with the increased run-time information given by the lineage structures, such as backend selection for heterogeneous systems. Experimental evaluation of example applications shows potential for performance improvements due to better cache utilization, as long as the overhead of lineage construction and management is kept low.
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| 9. |
- Fahringer, Thomas, et al.
(författare)
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ASKALON : a tool set for clusterand Grid computing
- 2005
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Ingår i: Concurrency and Computation. - : Wiley. - 1532-0626 .- 1532-0634. ; 17:2-4, s. 143-169
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Tidskriftsartikel (refereegranskat)abstract
- Performance engineering of parallel and distributed applications is a complex task that iterates through various phases, ranging from modeling and prediction, to performance measurement, experiment management, data collection, and bottleneck analysis. There is no evidence so far that all of these phases should/can be integrated into a single monolithic tool. Moreover, the emergence of computational Grids as a common single wide-area platform for high-performance computing raises the idea to provide tools as interacting Grid services that share resources, support interoperability among different users and tools, and, most importantly, provide omnipresent services over the Grid. We have developed the ASKALON tool set to support performance-oriented development of parallel and distributed (Grid) applications. ASKALON comprises four tools, coherently integrated into a service-oriented architecture. SCALEA is a performance instrumentation, measurement, and analysis tool of parallel and distributed applications. ZENTURIO is a general purpose experiment management tool with advanced support for multi-experiment performance analysis and parameter studies. AKSUM provides semi-automatic high-level performance bottleneck detection through a special-purpose performance property specification language. The PerformanceProphet enables the user to model and predict the performance of parallel applications at the early stages of development. In this paper we describe the overall architecture of the ASKALON tool set and outline the basic functionality of the four constituent tools. The structure of each tool is based on the composition and sharing of remote Grid services, thus enabling tool interoperability. In addition, a data repository allows the tools to share the common application performance and output data that have been derived by the individual tools. A service repository is used to store common portable Grid service implementations. A general-purpose Factory service is employed to create service instances on arbitrary remote Grid sites. Discovering and dynamically binding to existing remote services is achieved through registry services. The ASKALON visualization diagrams support both online and post-mortem visualization of performance and output data. We demonstrate the usefulness and effectiveness of ASKALON by applying the tools to real-world applications.
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| 10. |
- Gardfjäll, Peter, 1979-, et al.
(författare)
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Scalable Grid-wide capacity allocation with the SweGrid Accounting System (SGAS)
- 2008
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Ingår i: Concurrency and Computation. - : Wiley. - 1532-0626 .- 1532-0634. ; 20:18, s. 2089-2122
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Tidskriftsartikel (refereegranskat)abstract
- The SweGrid Accounting System (SGAS) allocates capacity in collaborative Grid environments by coordinating enforcement of Grid-wide usage limits as a means to offer usage guarantees and prevent overuse. SGAS employs a credit-based allocation model where Grid capacity is granted to projects via Grid-wide quota allowances that can be spent across the Grid resources. The resources Collectively enforce these allowances in a soft, real-time manner. SGAS is built on service-oriented principles with a strong focus on interoperability, and Web services standards. This article covers the SGAS design and implementation, which, besides addressing inherent Grid challenges (scale, security, heterogeneity, decentralization), emphasizes generality and flexibility to produce a customizable system with lightweight integration into different middleware and scheduling system combinations. We focus the discussion around the system design, a flexible allocation model, middleware integration experiences and scalability improvements via a distributed virtual banking system, and finally, an extensive set of testhed experiments. The experiments evaluate the performance of SGAS in terms of response times, request throughput, overall system scalability, and its performance impact on the Globus Toolkit 4 job submission software. We conclude that, for all practical purposes, the quota enforcement overhead incurred by SGAS on job submissions is not a limiting factor for the job-handling capacity of the job submission software.
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