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  • 1.
    Andersson, H. Robert H.
    et al.
    University West, Department of Engineering Science, Division of Mathematics, Computer and Surveying Engineering.
    De Blanche, Andreas
    University West, Department of Engineering Science, Division of Mathematics, Computer and Surveying Engineering.
    Lundqvist, Thomas
    University West, Department of Engineering Science, Division of Mathematics, Computer and Surveying Engineering.
    Flipping the Data Center Network: Increasing East-West Capacity Using Existing Hardware2017In: 2017 IEEE 42nd Conference on Local Computer Networks (LCN), 9-12 Oct. 2017, IEEE, 2017, p. 211-214, article id 8109355Conference paper (Refereed)
    Abstract [en]

    In today's datacenters, there is an increasing demand for more network traffic capacity. The majority of the increase in traffic is internal to the datacenter, i.e., it flows between different servers within the datacenter. This category of traffic is often referred to as east-west traffic and traditional hierarchical architectures are not well equipped to handle this type of traffic. Instead, they are better suited for the north-southbound traffic between hosts and the Internet. One suggested solution for this capacity problem is to adopt a folded CLOS topology, also known as spine-leaf, which often relies on software defined network (SDN) controllers to manage traffic. This paper shows that it is possible to implement a spine-leaf network using commodity-ofthe-shelf switches and thus improve the east-west traffic capacity. This can be obtained using low complexity configuration and edgerouting for load balancing, eliminating the need for a centralized SDN controller.

  • 2.
    Boklund, Andreas
    University West, Department of Technology, Mathematics and Computer Science, Division for Computer Science.
    Assessing Lectures, a case Study on the Student’s Perception2006In: Shifting perspectives in engineering education, Göteborg: Chalmers Tekniska Högskola , 2006, p. 96-103Chapter in book (Other academic)
  • 3.
    Boklund, Andreas
    University West, Department of Technology, Mathematics and Computer Science, Division for Computer Science.
    Performance Prediction of Future Generation Computer Systems2006In: Proceedings of the International Conference on Applied Computing: San Sebastian, Spain, Feb 25-28, 2006, p. 42-48Conference paper (Other academic)
  • 4.
    Boklund, Andreas
    University West, Department of Technology, Mathematics and Computer Science, Division for Computer Science.
    Wombat lurar nätskurkarna2006In: Datormagazin, ISSN 1650-1306, no 10, p. 86-90Article in journal (Other (popular science, discussion, etc.))
  • 5.
    Boklund, Andreas
    et al.
    University West, Department of Technology, Mathematics and Computer Science, Division for Computer Science.
    Christiernin, Stefan
    University West, Department of Technology, Mathematics and Computer Science, Division for Computer Science.
    Skriv en bandbreddsmätare i C2007In: Datormagazin, ISSN 1650-1306, no 7, p. 113-117Article in journal (Other (popular science, discussion, etc.))
  • 6.
    Boklund, Andreas
    et al.
    University West, Department of Technology, Mathematics and Computer Science, Division for Computer Science.
    Christiernin, Stefan
    University West, Department of Technology, Mathematics and Computer Science, Division for Computer Science.
    Johansson, Christer
    Lindell, Håkan
    University West, Department of Technology, Mathematics and Computer Science, Division for Computer Science.
    A Comprative Study of Forward and Reverse Engineering in UML Tools2007In: Proceedings of the International Conference on Applied Computing: Salamanca 2007, Spain, IADIS , 2007, p. 535-540Conference paper (Refereed)
    Abstract [en]

    In the process of developing computer based applications the use of descriptive models to depict the architecture and design of the application is practical and brings many advantages. The most commonly used standard today is the Unified Modeling Language. There are many tools that implemented support for this standard for modeling, and they vary in functionality. A comparative study, including a selection of these tools, will show advantages and disadvantages for each tool. The purpose of this study is to test a selection of these modeling tools for a typical three-tier layered web service application. The tools tested in this study are Microsoft Visual Studio 2005 .NET Beta, PowerDesigner and Visual Paradigm. Rational Rose would have been included if it would have supported C#. In this study tests are performed in regard to modeling a class diagram, forward engineering to source code from the class diagram and reverse engineering from source code to class diagram. Despite the shortage of diagram types MS Visual Studio proved to be the most reliable tool for this particular type of applications.

  • 7.
    Boklund, Andreas
    et al.
    University West. University West, Department of Technology, Mathematics and Computer Science. University West, Department of Technology, Mathematics and Computer Science, Division for Computer Science.
    Jiresjö, Christian
    University West, Department of Technology, Mathematics and Computer Science, Division for Computer Science.
    Mankefors, Stefan
    University West, Department of Technology, Mathematics and Computer Science, Division for Computer Science.
    The Story Behind Midnight, a Part Time High Performance Cluster2003In: International conference on Parallel and Distributed Processing Techniques and Applications / [ed] Hamid R. Arabnia, Las Vegas: CSREA Press , 2003, p. 173-178Conference paper (Other academic)
    Abstract [en]

    In this paper, we present the creation process andthe purpose behind the Midnight cluster. It isdisguised as a computer laboratory during the day,but turns into a high performance compute clusterduring the night.The main focus of this paper is on the basic issueswith creating a part time compute cluster. TheMidnight cluster was constructed to serve both as aCPU harvester and as a platform for further studies.The main goal of our upcoming research is toev aluate different methods for handling shapechangeand process management on the cluster, andhow these factors affect running processes, stabilityand performance.

  • 8.
    Boklund, Andreas
    et al.
    University West, Department of Economics and IT, Division of Computer Science and Informatics.
    Namaki, Nima
    University West, Department of Economics and IT, Division of Computer Science and Informatics.
    Mankefors-Christiernin, Stefan
    University West, Department of Economics and IT, Division of Computer Science and Informatics.
    Gustafsson, J
    University West, Department of Economics and IT, Division of Computer Science and Informatics.
    Lingbrand, M
    University West, Department of Economics and IT, Division of Computer Science and Informatics.
    Dual-core efficiency for engineering simulation applications2008In: 2008 International Conference on Parallel and Distributed Processing Techniques and Applications, PDPTA 2008: Las Vegas, NV; 14 July 2008 through 17 July 2008, 2008, p. 962-968Conference paper (Refereed)
  • 9.
    Boklund, Andreas
    et al.
    University West, Department of Technology, Mathematics and Computer Science, Division for Computer Science.
    Namaki, Nima
    University West, Department of Technology, Mathematics and Computer Science, Division for Computer Science.
    Mankefors-Christiernin, Stefan
    University West, Department of Technology, Mathematics and Computer Science, Division for Computer Science.
    Jiresjö, Christian
    University West, Department of Economics and IT, Division of Computer Science and Informatics.
    A characterisation tool for the impact of network deficiencies on HPC applications2008In: Proceedings of the 2008 International Conference on Parallel and Distributed Processing Techniques and Applications, PDPTA 2008, 2008, p. 888-894Conference paper (Other academic)
  • 10. Calås, G.
    et al.
    Christiernin, Stefan
    University West, Department of Technology, Mathematics and Computer Science, Division for Computer Science.
    Boklund, Andreas
    University West, Department of Technology, Mathematics and Computer Science, Division for Computer Science.
    Robustness Analysis and Technology Forecasting: Survey on a Missing Combination in Software Development2006In: Proceedings of the International conference on Software Engineering :: innsbruck, Austria, 2006, p. 329-334Conference paper (Other academic)
  • 11.
    Calås, Göran
    et al.
    University West, Department of Technology, Mathematics and Computer Science, Division for Computer Science.
    Boklund, Andreas
    University West, Department of Technology, Mathematics and Computer Science, Division for Computer Science.
    Mankefors-Christiernin, Stefan
    University West, Department of Technology, Mathematics and Computer Science, Division for Computer Science.
    A First Draft of RATF: A Method Combining Robustness Analysis and Technology Forecasting2006In: Information Technology: New Generations, 2006. ITNG 2006. Third International Conference on, 2006, p. 72-77Conference paper (Other academic)
    Abstract [en]

    This paper is based on an extensive study performed on a large software suite for over a decade. From the experiences derived from this study we created a first draft of a method combining an extended robustness analysis (RA) method with the future oriented method of technology forecasting (TF). In this method TF provides information about the systems future evolution to the RA which then generates the software design. The RA and TF methods then form a feedback loop, which results in an improved reusable and robust software design. The purpose of the RATF method is to predict the evolutional path of the software system, thus making preparations for (example) functionality that will be needed in future generations, i.e. utilizing the power-of-prediction to implement the base of tomorrow's functions today

  • 12.
    Calås, Göran
    et al.
    University West, Department of Technology, Mathematics and Computer Science, Division for Computer Science.
    Mankefors-Christiernin, Stefan
    University West, Department of Technology, Mathematics and Computer Science, Division for Computer Science.
    Boklund, Andreas
    University West, Department of Technology, Mathematics and Computer Science, Division for Computer Science.
    Combining robust analysis and technology forecasting: A missing combination in contemporary methods2006In: Proceedings of the IASTED International Conference on Software Engineering: as part of the 24th IASTED International Multi-Conference on APPLIED INFORMATICS, Innsbruck, 2006, p. 329-334Conference paper (Other academic)
    Abstract [en]

    Seven software engineering methods and one general purpose system engineering method TRIZ was evaluated concerning their abilities to combine software technology forecasting, that is prediction of potential software evolution with robustness analysis, which is a method to model a system tolerant to changes. None of the investigated software engineering method or process concepts combines software technology forecasting with robustness analysis to any great extent. Several of the methods evaluated do contribute with techniques and principles, that potentially could be combined and give systematically technology forecasting with comprehensively robustness analysis though. This defines a new frontier for research into a combined "super class" method for software development.

  • 13.
    Christiernin Gustafsson, Linn
    et al.
    University West, Department of Technology, Mathematics and Computer Science, Division for Computer Science.
    Gustavsson, M.
    Ohlsson, A.
    Boklund, Andreas
    University West, Department of Technology, Mathematics and Computer Science, Division for Computer Science.
    Prototyping a Multi-Layered Help - a User Involved Exploratory Design2006In: Proceedings of the International Conference on Applied Computing: San Sebastian, Spain. Feb 25-28, 2006, p. 315-323Conference paper (Other academic)
  • 14.
    Christiernin, Linn G.
    et al.
    University West, Department of Economics and IT, Division of Computer Science and Informatics.
    Mankefors-Christiernin, Stefan
    University West, Department of Economics and IT, Division of Computer Science and Informatics.
    Olsson, A
    Boklund, Andreas
    University West, Department of Economics and IT, Division of Computer Science and Informatics.
    A case study evaluation of RDPM: a process confirmed successfulIn: Interacting with computers, ISSN 0953-5438, E-ISSN 1873-7951Article in journal (Refereed)
  • 15.
    De Blanche, Andreas
    University West, Department of Engineering Science, Division of Computer, Electrical and Surveying Engineering. Institutionen för data- och informationsteknik, Datorteknik (Chalmers.
    A Slowdown Prediction Method to Improve Memory Aware Scheduling2016Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Scientific and technological advances in the area of integrated circuits have allowed the performance of microprocessors to grow exponentially since the late 1960's. However, the imbalance between processor and memory bus capacity has increased in recent years. The increasing on-chip-parallelism of multi-core processors has turned the memory subsystem into a key factor for achieving high performance. When two or more processes share the memory subsystem their execution times typically increase, even at relatively low levels of memory traffic. Current research shows that a throughput increase of up to 40% is possible if the job-scheduler can minimizes the slowdown caused by memory contention in industrial multi-core systems such as high performance clusters, datacenters or clouds. In order to optimize the throughput the job-scheduler has to know how much slower the process will execute when co-scheduled on the same server as other processes. Consequently, unless the slowdown is known, or can be fairly well estimated, the scheduling becomes pure guesswork and the performance suffers. The central question addressed in this thesis is how the slowdown caused by memory traffic interference between processes executing on the same server can be predicted and to what extent. This thesis presents and evaluates a new slowdown prediction method which estimates how much longer a program will execute when co-scheduled on the same multi-core server as another program. The method measures how external memory traffic affects a program by generating different levels of synthetic memory traffic while observing the change in execution time. Based on the observations it makes a first order prediction of how much slowdown the program will experience when exposed to external memory traffic. Experimental results show that the method's predictions correlate well with the real measured slowdowns. Furthermore, it is shown that scheduling based on the new slowdown prediction method yields a higher throughput than three other techniques suggested for avoiding co-scheduling slowdowns caused by memory contention. Finally, a novel scheme is suggested to avoid some of the worst co-schedules, thus increasing the system throughput.

  • 16.
    de Blanche, Andreas
    University West, Department of Economics and IT, Division of Computer Science and Informatics.
    Operativsystem: teori och praktiskt handhavande2008Book (Other academic)
  • 17.
    De Blanche, Andreas
    et al.
    University West, Department of Engineering Science, Division of Computer and Electrical Engineering.
    Lundqvist, Thomas
    University West, Department of Engineering Science, Division of Computer and Electrical Engineering.
    A methodology for estimating co-scheduling slowdowns due to memory bus contention on multicore nodes2014In: Proceedings of the IASTED International Conference on Parallel and Distributed Computing and Networks, PDCN 2014, ACTA Press, 2014, p. 216-223Conference paper (Refereed)
    Abstract [en]

    When two or more programs are co-scheduled on the same multicore computer they might experience a slowdown due to the limited off-chip memory bandwidth. According to our measurements, this slowdown does not depend on the total bandwidth use in a simple way. One thing we observe is that a higher memory bandwidth usage will not always lead to a larger slowdown. This means that relying on bandwidth usage as input to a job scheduler might cause non-optimal scheduling of processes on multicore nodes in clusters, clouds, and grids. To guide scheduling decisions, we instead propose a slowdown based characterization approach. Real slowdowns are complex to measure due to the exponential number of experiments needed. Thus, we present a novel method for estimating the slowdown programs will experience when co-scheduled on the same computer. We evaluate the method by comparing the predictions made with real slowdown data and the often used memory bandwidth based method. This study show that a scheduler relying on slowdown based categorization makes fewer incorrect co-scheduling choices and the negative impact on program execution times is less than when using a bandwidth based categorization method.

  • 18.
    De Blanche, Andreas
    et al.
    University West, Department of Engineering Science, Division of Computer and Electrical Engineering.
    Lundqvist, Thomas
    University West, Department of Engineering Science, Division of Computer and Electrical Engineering.
    Addressing characterization methods for memory contention aware co-scheduling2015In: Journal of Supercomputing, ISSN 0920-8542, E-ISSN 1573-0484, Vol. 71, no 4, p. 1451-1483Article in journal (Refereed)
    Abstract [en]

    The ability to precisely predict how memory contention degrades performance when co-scheduling programs is critical for reaching high performance levels in cluster, grid and cloud environments. In this paper we present an overview and compare the performance of state-of-the-art characterization methods for memory aware (co-)scheduling. We evaluate the prediction accuracy and co-scheduling performance of four methods: one slowdown-based, two cache-contention based and one based on memory bandwidth usage. Both our regression analysis and scheduling simulations find that the slowdown based method, represented by Memgen, performs better than the other methods. The linear correlation coefficient (Formula presented.) of Memgen's prediction is 0.890. Memgen's preferred schedules reached 99.53 % of the obtainable performance on average. Also, the memory bandwidth usage method performed almost as well as the slowdown based method. Furthermore, while most prior work promote characterization based on cache miss rate we found it to be on par with random scheduling of programs and highly unreliable.

  • 19.
    De Blanche, Andreas
    et al.
    University West, Department of Engineering Science, Division of Computer, Electrical and Surveying Engineering.
    Lundqvist, Thomas
    University West, Department of Engineering Science, Division of Computer, Electrical and Surveying Engineering.
    Disallowing Same-program Co-schedules to Improve Efficiency in Quad-core Servers2017Conference paper (Other academic)
    Abstract [en]

    Programs running on different cores in a multicore serverare often forced to share resources like off-chip memory,caches, I/O devices, etc. This resource sharing often leadsto degraded performance, a slowdown, for the programsthat share the resources. A job scheduler can improve performance by co-scheduling programs that use different resources on the same server. The most common approachto solve this co-scheduling problem has been to make jobschedulers resource aware, finding ways to characterize andquantify a program’s resource usage. We have earlier suggested a simple, program and resource agnostic, scheme asa stepping stone to solving this problem: Avoid TerribleTwins, i.e., avoid co-schedules that contain several instancesfrom the same program. This scheme showed promising results when applied to dual-core servers. In this paper, weextend the analysis and evaluation to also cover quad-coreservers. We present a probabilistic model and empirical datathat show that execution slowdowns get worse as the numberof instances of the same program increases. Our schedulingsimulations show that if all co-schedules containing multiple instances of the same program are removed, the averageslowdown is decreased from 54% to 46% and that the worstcase slowdown is decreased from 173% to 108%.

  • 20.
    De Blanche, Andreas
    et al.
    University West, Department of Engineering Science, Division of Computer, Electrical and Surveying Engineering.
    Lundqvist, Thomas
    University West, Department of Engineering Science, Division of Computer, Electrical and Surveying Engineering.
    Initial Formulation of Why Disallowing Same Program Co-schedules Improves Performance2017In: Co-Scheduling of HPC Applications / [ed] Carsten Trinitis, Josef Weidendorfer, Netherlands: IOS Press, 2017, 1, p. 95-113Chapter in book (Refereed)
    Abstract [en]

    Co-scheduling processes on different cores in the same server might leadto excessive slowdowns if they use the same shared resource, like a memory bus. Ifpossible, processes with a high shared resource use should be allocated to differentserver nodes to avoid contention, thus avoiding slowdown. This article proposesthe more general principle that twins, i.e. several instances of the same program,should be allocated to different server nodes. The rational for this is that instancesof the same program use the same resources and they are more likely to be eitherlow or high resource users. High resource users should obviously not be combined,but a bit non-intuitively, it is also shown that low resource users should also notbe combined in order to not miss out on better scheduling opportunities. This isverified using both a probabilistic argument as well as experimentally using tenprograms from the NAS parallel benchmark suite running on two different systems.By using the simple rule of forbidding these terrible twins, the average slowdownis shown to decrease from 6.6% down to 5.9% for System A and from 9.5% to8.3% for System B. Furthermore, the worst case slowdown is lowered from 12.7%to 9.0% and 19.5% to 13% for systems A and B, respectively. Thus, indicating aconsiderable improvement despite the rule being program agnostic and having noinformation about any program’s resource usage or slowdown behavior.

  • 21.
    De Blanche, Andreas
    et al.
    University West, Department of Engineering Science, Division of Mathematics, Computer and Surveying Engineering.
    Lundqvist, Thomas
    University West, Department of Engineering Science, Division of Mathematics, Computer and Surveying Engineering.
    Node Sharing for Increased Throughput and Shorter Runtimes: an Industrial Co-Scheduling Case Study2018In: Proceedings of the 3rd Workshop on Co-Scheduling of HPC Applications (COSH 2018): Held together with HiPEAC 2018 / [ed] Trinitis, Carsten; Weidendorfer, Josef, 2018, p. 15-20Conference paper (Refereed)
    Abstract [en]

    The allocation of jobs to nodes and cores in industrial clusters is often based on queue-system standard settings, guesses or perceived fairness between different users and projects. Unfortunately, hard empirical data is often lacking and jobs are scheduled and co-scheduled for no apparent reason. In this case-study, we evaluate the performance impact of co-scheduling jobs using three types of applications and an existing 450+ node cluster at a company doing large-scale parallel industrial simulations. We measure the speedup when co-scheduling two applications together, sharing two nodes, compared to running the applications on separate nodes. Our results and analyses show that by enabling co-scheduling we improve performance in the order of 20% both in throughput and in execution times, and improve the execution times even more if the cluster is running with low utilization. We also find that a simple reconfiguration of the number of threads used in one of the applications can lead to a performance increase of 35-48% showing that there is a potentially large performance increase to gain by changing current practice in industry.

  • 22.
    De Blanche, Andreas
    et al.
    University West, Department of Engineering Science, Division of Computer, Electrical and Surveying Engineering.
    Lundqvist, Thomas
    University West, Department of Engineering Science, Division of Computer, Electrical and Surveying Engineering.
    Terrible Twins: A Simple Scheme to Avoid Bad Co-Schedule2016In: Proceedings of the 1st COSH Workshop on Co-Scheduling of HPC Applications / [ed] Trinitis, Carsten ; Weidendorfer, Josef, Munchen, 2016, Vol. 1, p. 1-6Conference paper (Refereed)
    Abstract [en]

    Co-scheduling processes on different cores in the same server might lead to excessive slowdowns if they use a shared resource,like the memory bus. If possible, processes with a high shared resource use should be allocated to different server nodes to avoid contention, thus avoiding slowdown.This paper introduces the simple scheme of avoiding to coschedule twins, i.e., several instances of the same program.The rational for this is that instances of the same program use the same resources and they are more likely to be either low or high resource users − high resource users should obviously not be combined, but a bit non-intuitively, it is also shown that low resource users should also not be combined in order to not miss out on better scheduling opportunities.This is verified using both a statistical argument as well as experimentally using ten programs from the NAS parallel benchmark suite. By using the simple rule of forbidding twins, the average slowdown is shown to decrease from 6.6% down to 5.9%, and the worst case slowdown is lowered from 12.7% to 9.0%, indicating a considerable improvement despite having no information about any programs' resource usage or slowdown behavior.

  • 23.
    de Blanche, Andreas
    et al.
    University West, Department of Economics and IT, Division of Computer Science and Informatics.
    Mankefors-Christiernin, Stefan
    University West, Department of Economics and IT, Division of Computer Science and Informatics.
    Availability of Unused Computational Resources in an Ordinary Office Environment2010In: Journal of Circuits, Systems and Computers, ISSN 0218-1266, Vol. 19, no 3, p. 557-572Article in journal (Refereed)
    Abstract [en]

    The study presented in this paper highlights an important issue that was subject for discussionsand research about a decade ago and now have gained new interest with the current advances ofgrid computing and desktop grids. New techniques are being invented on how to utilize desktopcomputers for computational tasks but no other study, to our knowledge, has explored theavailability of the said resources. The general assumption has been that there are resources andthat they are available. The study is based on a survey on the availability of resources in anordinary o±ce environment. The aim of the study was to determine if there are truly usableunder-utilized networked desktop computers available for non-desktop tasks during the off-hours. We found that in more than 96% of the cases the computers in the current investigationwas available for the formation of part-time (night and weekend) computer clusters. Finally wecompare the performance of a full time and a metamorphosic cluster, based on one hypotheticallinear scalable application and a real world welding simulation.

  • 24.
    de Blanche, Andreas
    et al.
    University West, Department of Economics and IT, Division of Computer Science and Informatics.
    Mankefors-Christiernin, Stefan
    University West, Department of Economics and IT, Division of Computer Science and Informatics.
    Method for Experimental Measurement of an Applications Memory Bus Usage2010In:   / [ed] Hamid Arabnia, CSREA Press , 2010Conference paper (Refereed)
    Abstract [en]

    The disproportion between processor and memory bus capacities has increased constantly during the last decades. With the introduction of multi-core processors the memory bus capacity is divided between the simultaneously executing processes (cores). The memory bus capacity directly affects the number of applications that can be executed simultaneously at its full potential. Thus, against this backdrop it becomes important to estimate how the limitation of the memory bus effects the applications performance. Towards this end we introduce a method and a tool for experimental estimation of an applications memory requirement as well as the impact of sharing the memory bus has on the execution times. The tool enables black-box approximate profiling of an applications memory bus usage during execution. It executes entirely in user-space and does not require access to the application code, only the binary. 

  • 25.
    de Blanche, Andreas
    et al.
    University West, Department of Economics and IT, Division of Computer Science and Informatics.
    Mankefors-Christiernin, Stefan
    University West, Department of Economics and IT, Division of Computer Science and Informatics.
    Minimizing Total Cost ($$) and Maximizing Throughput: A Metric for Node versus Core Usage in Multi-Core Clusters2010In: Proceedings of the International conference on Parallel and Distributed Processing Techniques and Applications:   / [ed] Hamid R. Arabnia, Las Vegas: CSREA Press , 2010, p. 241-248Conference paper (Refereed)
    Abstract [en]

    When most commercial clusters had one processor core each, decreasing the runtime meant executing the application over more nodes – the associated cost (in $) would scale linearly with the number of nodes. However with the recent advances of multi-core processors the execution time can be increased by utilizing more nodes or by utilizing more cores in the same nodes. In the industrial cluster environments a key question is how to run the applications, to minimize the total cost while maximizing the throughput and solution times of the individual jobs. The number of core used and their contribution to the total runtime reduction is especially interesting since companies often use commercial software that is licensed per year and process. The annual license cost of one single process is often far greater than that of a complete cluster node including maintenance and power. In this paper we present a metric for the calculation of the optimal way to run an application on a cluster consisting of multi-core nodes in order to minimize the cost of executing the said job. 

  • 26.
    de Blanche, Andreas
    et al.
    University West, Department of Engineering Science, Division of Automation and Computer Engineering.
    Namaki, Nima
    University West, Department of Engineering Science, Division of Automation and Computer Engineering.
    Mankefors-Christiernin, Stefan
    University West, Department of Economics and IT, Division of Computer Engineering.
    Multicore Clusters for CFD Simulations: Comparative Study of Three CFD-Softwares2012In: PROCEEDINGS OFTHE 2012 INTERNATIONAL CONFERENCE ONPARALLEL AND DISTRIBUTED PROCESSING TECHNIQUES ANDAPPLICATIONS, PART II / [ed] Hamid R. Arabnia, Hiroshi Ishii, Minoru Ito Kazuki Joe, Hiroaki Nishikawa, CSREA Press, 2012, p. 855-852Conference paper (Refereed)
    Abstract [en]

    Multicore processors have come to stay, fulfill Moore’s law and might very well revolutionize the computer industry. However, we are now in a transitional period before the new programming models, numerical algorithms and general computer architecture have been developed and the software has been rewritten. This paper focuses on the effects multicore based systems have on industrial computational fluid dynamics (CFD) simulations. The most significant finding was that five of the models ran faster when only one process was executed on each multicore node instead of two. In these cases the execution time was increased by between 6.5% and 64% with a median increase of 10% when utilizing both cores.

  • 27.
    Jiresjö, Christian
    et al.
    University West, Department of Technology, Mathematics and Computer Science, Division for Computer Science.
    Boklund, Andreas
    University West, Department of Technology, Mathematics and Computer Science, Division for Computer Science.
    Benefits of Alternative Network Topologies For COTS Linux Clusters2006In: Proceedings of the International Conference on Applied Computing: San Sebastian, Spain. Feb 25-28, 2006, p. 457-461Conference paper (Other academic)
    Abstract [en]

    The focus of this paper is to evaluate the use of two different network topologies for Ethernet networks in small Common

    Off The Shelf (COTS) clusters. The fully meshed network topology was evaluated and its impact on latency and

    bandwidth was measured and compared to the more traditional switched network topology. This was done at MPI level

    by measuring the point-to-point round trip latency (ping-pong) and all-to-alla bandwidth for different sized messages.

    The results from the experiments are presented and the overall the benefits and drawbacks of the both approaches are

    discussed.

  • 28.
    Lindström, Per
    et al.
    University West, Department of Engineering Science, Division of Manufacturing Processes.
    de Blanche, Andreas
    University West, Department of Engineering Science, Division of Computer and Electrical Engineering.
    Integration and Optimization of a 64-core HPC for FEM- and/or CFD Welding Simulations2013In: Improving Simulation Prediction by Using Advanced Material Models / [ed] Nafems Nordic, Bernau am Chiemsee: NAFEMS , 2013, p. 13-18Conference paper (Refereed)
  • 29.
    Lundmark, Elias
    et al.
    University West, Department of Engineering Science.
    Persson, Chris
    University West, Department of Engineering Science.
    De Blanche, Andreas
    University West, Department of Engineering Science, Division of Mathematics, Computer and Surveying Engineering.
    Lundqvist, Thomas
    University West, Department of Engineering Science, Division of Mathematics, Computer and Surveying Engineering.
    Increasing Throughput of Multiprogram HPC Workloads: Evaluating a SMT Co-Scheduling Approach2017Conference paper (Refereed)
    Abstract [en]

    Simultaneous Multithreading (SMT) is a technique that allows formore efficient processor utilization by scheduling multiple threadson a single physical core. Previous research have shown an averagethroughput increase of around 20% with an SMT level of two, e.g.two threads per core. However, a bad combination of threads canactually result in decreased performance. To be conservative, manyHPC-systems have SMT disabled, thus, limiting the number ofscheduling slots in the system to one per core. However, for SMT tonot hurt performance, we need to determine which threads shouldshare a core. In this poster, we use 30 random SPEC CPU job mixedon a twelve-core Broadwell based node, to study the impact ofenabling SMT using two different co-scheduling strategies. Theresults show that SMT can increase performance especially whenusing no-same-program co-scheduling.

  • 30.
    Lundqvist, Thomas
    et al.
    University West, Department of Engineering Science, Division of Mathematics, Computer and Surveying Engineering.
    De Blanche, Andreas
    University West, Department of Engineering Science, Division of Mathematics, Computer and Surveying Engineering.
    Andersson, H. Robert H.
    University West, Department of Engineering Science, Division of Mathematics, Computer and Surveying Engineering.
    Thing-to-thing electricity micro payments using blockchain technology2017In: Global Internet of Things Summit (GIoTS), 2017: Proceedings of a meeting held 6-9 June 2017, Geneva, Switzerland, Institute of Electrical and Electronics Engineers (IEEE), 2017, article id 8016254Conference paper (Refereed)
    Abstract [en]

    Thing-to-thing payments are a key enabler in the Internet of Things (IoT) era, to ubiquitously allow for devices to pay each other for services without any human interaction. Traditional credit card-based systems are not able to handle this new paradigm, however blockchain technology is a promising payment candidate in this context. The prominent example of blockchain technology is Bitcoin, with its decentralized structure and ease of account creation. This paper presents a proof-of-concept implementation of a smart cable that connects to a smart socket and without any human interaction pays for electricity. In this paper, we identify several obstacles for the widespread use of bitcoins in thing-to-thing payments. A critical problem is the high transaction fees in the Bitcoin network when doing micro transactions. To reduce this impact, we present a single-fee micro-payment protocol that aggregates multiple smaller payments incrementally into one larger transaction needing only one transaction fee. The proof-of concept shows that trustless, autonomous, and ubiquitous thing-to-thing micro-payments is no longer a future technology.

  • 31.
    Namaki, Nima
    et al.
    University West, Department of Economics and IT, Division of Computer Science and Informatics.
    de Blanche, Andreas
    University West, Department of Economics and IT, Division of Computer Science and Informatics.
    Mankefors-Christiernin, Stefan
    University West, Department of Economics and IT, Division of Computer Science and Informatics.
    A Tool for Processor Dependency Characterization of HPC Applications2009In: Proceedings for the HPC Asia & APAN 2009, Hsinchu, Taiwan: National Center for High-Performance Computing , 2009, p. 70-76Conference paper (Other academic)
    Abstract [en]

    In this paper we have implemented and verified Cpugen, a tool for characterization of processor resource utilization of HPC applications .Toward this end we implemented Cpugen, an application with good accuracy for processor load generation. Cpugen was verified through three different phases of passive, active and real world application measurements. The measurement results show that our implemented method is a viable option for non-intrusive, stable and robust load generation. The error range for all generated target loads are between 0.00% minimum and 1.04% maximum, with a median deviation of 0.11%. We can conclude that the method utilized in this investigation provides the ability to generate stable and robust processor load.

  • 32.
    Namaki, Nima
    et al.
    University West, Department of Economics and IT, Division of Computer Engineering.
    de Blanche, Andreas
    University West, Department of Economics and IT, Division of Computer Engineering.
    Mankefors-Christiernin, Stefan
    University West, Department of Economics and IT, Division of Computer Engineering.
    Exhausted Dominated Performance: Basic Proof of Concept2010In: International conference on Parallel and Distributed Processing Techniques and Applications  / [ed] Hamid R. Arabnia, Las Vegas: CSREA , 2010, p. 63-67Conference paper (Refereed)
  • 33.
    Namaki, Nima
    et al.
    University West, Department of Economics and IT, Division of Computer Science and Informatics.
    de Blanche, Andreas
    University West, Department of Economics and IT, Division of Computer Science and Informatics.
    Mankefors-Christiernin, Stefan
    University West, Department of Economics and IT, Division of Computer Science and Informatics.
    Exhaustion dominated performance: a first attempt2009In: SAC '09: Proceedings of the 2009 ACM symposium on Applied Computing, ACM , 2009, p. 1011-1012Conference paper (Other academic)
    Abstract [en]

    In this paper we present a first attempt to an analytical method to discover and understand how the available resources influence the execution time. Our method is based on a piecewise linear model for dominating execution limitations and black-box observations. We verify this analysis method by a set of real-world experiments. Finally, we conclude that the different effects follow a linear superposition within a certain range.

  • 34.
    Namaki, Nima
    et al.
    University West, Department of Economics and IT, Division of Computer Science and Informatics.
    de Blanche, Andreas
    University West, Department of Economics and IT, Division of Computer Science and Informatics.
    Mankefors-Christiernin, Stefan
    University West, Department of Economics and IT, Division of Computer Science and Informatics.
    Exhaustion dominated performance: an empirical method evalutationIn: Journal of Parallel and Distributed Computing, ISSN 0743-7315, E-ISSN 1096-0848Article in journal (Refereed)
  • 35. Persson, R.
    et al.
    Mankefors Christiernin, Stefan
    University West, Department of Technology, Mathematics and Computer Science, Division for Computer Science.
    Boklund, Andreas
    University West, Department of Technology, Mathematics and Computer Science, Division for Computer Science.
    Concept Model of an Object Detecting Mobile Robot in an Indoor Environment2006In: Proceedings of the International Conference on Applied Computing: San Sebastian, Spain. Feb 25-28, 2006, p. 130-136Conference paper (Other academic)
1 - 35 of 35
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