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  • 1.
    Amoson, Jonas
    et al.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avd för automation och datateknik.
    Lundqvist, Thomas
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avd för automation och datateknik.
    A light-weigh non-hierarchical file system navigation extension2012Ingår i: Proceedings of the 7th International Workshop on Plan 9 / [ed] Eric Jul, Dublin, Ireland, 2012, s. 11-13Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    Drawbacks in organising and finding files in hierarchies have led researchers to explorenon-hierarchical and search-based filesystems, where file identity and belonging is pred-icated by tagging files to categories. We have implemented a chdir() shell extension en-abling navigation to a directory using a search expression. Our extension is light-weightand avoids modifying the file system to guarantee backwards compatibility for applicationsrelying on normal hierarchical file namespaces.

    Ladda ner fulltext (pdf)
    searchpath_amoson_lundqvist_2012
  • 2.
    Andersson, H. Robert H.
    et al.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för Matematik, Data- och Lantmäteriteknik.
    de Blanche, Andreas
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för Matematik, Data- och Lantmäteriteknik.
    Lundqvist, Thomas
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för Matematik, Data- och Lantmäteriteknik.
    Flipping the Data Center Network: Increasing East-West Capacity Using Existing Hardware2017Ingår i: 2017 IEEE 42nd Conference on Local Computer Networks (LCN), 9-12 Oct. 2017, IEEE, 2017, s. 211-214, artikel-id 8109355Konferensbidrag (Refereegranskat)
    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.

  • 3.
    de Blanche, Andreas
    et al.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avd för data- och elektroteknik.
    Lundqvist, Thomas
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avd för data- och elektroteknik.
    A methodology for estimating co-scheduling slowdowns due to memory bus contention on multicore nodes2014Ingår i: Proceedings of the IASTED International Conference on Parallel and Distributed Computing and Networks, PDCN 2014, ACTA Press, 2014, s. 216-223Konferensbidrag (Refereegranskat)
    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.

  • 4.
    de Blanche, Andreas
    et al.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avd för data- och elektroteknik.
    Lundqvist, Thomas
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avd för data- och elektroteknik.
    Addressing characterization methods for memory contention aware co-scheduling2015Ingår i: Journal of Supercomputing, ISSN 0920-8542, E-ISSN 1573-0484, Vol. 71, nr 4, s. 1451-1483Artikel i tidskrift (Refereegranskat)
    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.

  • 5.
    de Blanche, Andreas
    et al.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för data-, elektro- och lantmäteriteknik.
    Lundqvist, Thomas
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för data-, elektro- och lantmäteriteknik.
    Disallowing Same-program Co-schedules to Improve Efficiency in Quad-core Servers2017Ingår i: Proceedings of the Joined Workshops COSH 2017 and VisorHPC 2017 / [ed] Clauss, Carsten; Lankes, Stefan; Trinitis, Carsten; Weidendorfer, Josef, 2017, s. 1-7Konferensbidrag (Refereegranskat)
    Abstract [en]

    Programs running on different cores in a multicore server are often forced to share resources like off-chip memory,caches, I/O devices, etc. This resource sharing often leads to degraded performance, a slowdown, for the program sthat 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 job schedulers resource aware, finding ways to characterize and quantify a program’s resource usage. We have earlier suggested a simple, program and resource agnostic, scheme as a stepping stone to solving this problem: Avoid Terrible Twins, i.e., avoid co-schedules that contain several instances from the same program. This scheme showed promising results when applied to dual-core servers. In this paper, we extend the analysis and evaluation to also cover quad-core servers. We present a probabilistic model and empirical data that show that execution slowdowns get worse as the number of instances of the same program increases. Our scheduling simulations show that if all co-schedules containing multiple instances of the same program are removed, the average slowdown is decreased from 54% to 46% and that the worst case slowdown is decreased from 173% to 108%.

  • 6.
    de Blanche, Andreas
    et al.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för data-, elektro- och lantmäteriteknik.
    Lundqvist, Thomas
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för data-, elektro- och lantmäteriteknik.
    Initial Formulation of Why Disallowing Same Program Co-schedules Improves Performance2017Ingår i: Co-Scheduling of HPC Applications / [ed] Carsten Trinitis, Josef Weidendorfer, Netherlands: IOS Press, 2017, 1, s. 95-113Kapitel i bok, del av antologi (Refereegranskat)
    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.

  • 7.
    de Blanche, Andreas
    et al.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för Matematik, Data- och Lantmäteriteknik.
    Lundqvist, Thomas
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för Matematik, Data- och Lantmäteriteknik.
    Node Sharing for Increased Throughput and Shorter Runtimes: an Industrial Co-Scheduling Case Study2018Ingår i: Proceedings of the 3rd Workshop on Co-Scheduling of HPC Applications (COSH 2018): Held together with HiPEAC 2018 / [ed] Trinitis, Carsten; Weidendorfer, Josef, 2018, s. 15-20Konferensbidrag (Refereegranskat)
    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.

    Ladda ner fulltext (pdf)
    COSH2018-deBlanche-Lundqvist
  • 8.
    de Blanche, Andreas
    et al.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för data-, elektro- och lantmäteriteknik.
    Lundqvist, Thomas
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för data-, elektro- och lantmäteriteknik.
    Terrible Twins: A Simple Scheme to Avoid Bad Co-Schedule2016Ingår i: Proceedings of the 1st COSH Workshop on Co-Scheduling of HPC Applications / [ed] Trinitis, Carsten ; Weidendorfer, Josef, Munchen, 2016, Vol. 1, s. 1-6Konferensbidrag (Refereegranskat)
    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.

    Ladda ner fulltext (pdf)
    fulltext
  • 9.
    Loconsole, Annabella
    et al.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för Matematik, Data- och Lantmäteriteknik.
    Lundqvist, Thomas
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för Matematik, Data- och Lantmäteriteknik.
    Tano, Ingrid
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för Matematik, Data- och Lantmäteriteknik.
    de Blanche, Andreas
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för Matematik, Data- och Lantmäteriteknik.
    Comparing the CDIO educational framework with University West’s WIL certification: do they complement each other?2021Ingår i: VILÄR: 9-10 of December, 2021, University West, Trollhättan, 2021, s. 15-16Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    Higher education institutions (HEIs) need to continuously improve their quality to prepare the students to the society of the 21st Century. They need to develop efficient ways of collaborating with various partners in the surrounding community. Close ties with business and industry, and diversity among staff and students are necessary, especially within engineering education. An engineering degree should prepare students to develop a wide range of knowledge and skills. These range from technical, scientific, and mathematical knowledge but also soft skills such as teamwork, business skills and critical analysis, which are also central sustainability competences. It is vital that learning for engineers takes place in the context of authentic engineering problems and processes to develop these skills and to put theory into practice. 

    Several initiatives focused on incorporating these skills in higher education exists. CDIO (Conceive, Design, Implement, Operate) is one of the most prominent initiatives within engineering education. CDIO targets the typical tasks an engineer performs when bringing new systems, products and services to the market or the society. The CDIO initiative was created to strengthen active and problem-based learning and improving students' communication and professional skills. CDIO focus on improving practical and work-related skills to better prepare engineering students for their future professional life.

    University West employs another initiative, Arbetsintegrerat lärande (AIL), which “roughly” translates to Work Integrated Learning (WIL). WIL shares much of the same philosophy as CDIO. All programs at University West are currently undergoing an AIL-certification process. For engineering programs, that have been working with CDIO, it is interesting to compare them. It is currently unclear how they differ. 

    In this study we compare the CDIO educational framework with the WIL-certification through a series of workshops to identify in which areas they overlap and which areas they differ. Would a program that has adopted the CDIO educational framework automatically fulfill the WIL-certification?

     

    Ladda ner fulltext (pdf)
    VILÄR2021
  • 10.
    Lundmark, Elias
    et al.
    Högskolan Väst, Institutionen för ingenjörsvetenskap.
    Persson, Chris
    Högskolan Väst, Institutionen för ingenjörsvetenskap.
    de Blanche, Andreas
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för Matematik, Data- och Lantmäteriteknik.
    Lundqvist, Thomas
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för Matematik, Data- och Lantmäteriteknik.
    Increasing Throughput of Multiprogram HPC Workloads: Evaluating a SMT Co-Scheduling Approach2017Konferensbidrag (Refereegranskat)
    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.

  • 11.
    Lundqvist, Thomas
    et al.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för Matematik, Data- och Lantmäteriteknik.
    de Blanche, Andreas
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för Matematik, Data- och Lantmäteriteknik.
    Andersson, H. Robert H.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för Matematik, Data- och Lantmäteriteknik.
    Thing-to-thing electricity micro payments using blockchain technology2017Ingår i: 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, s. 261-266, artikel-id 8016254Konferensbidrag (Refereegranskat)
    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.

    Ladda ner fulltext (pdf)
    fulltext
  • 12.
    Lundqvist, Thomas
    et al.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för Matematik, Data- och Lantmäteriteknik.
    Loconsole, Annabella
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för Matematik, Data- och Lantmäteriteknik.
    Tano, Ingrid
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för Matematik, Data- och Lantmäteriteknik.
    de Blanche, Andreas
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för Matematik, Data- och Lantmäteriteknik.
    Comparing the Cdio Standards with the Work Integrated Learning Certification2022Ingår i: Proceedings of the International CDIO Conference 18th International CDIO Conference, CDIO 2022 Reykjavik / [ed] Gudjonsdottir M.S., Audunsson H., Donoso A.M., Kristjansson G., Saemundsdottir I., Foley J.T., Kyas M., Sripakagorn A., Roslof J., Bennedsen J., Edstrom K., Kuptasthien N., Lyng R., Chalmers University of Technology , 2022, s. 37-47Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    Improving the quality of higher education is an important responsibility of universities and colleges. Several approaches have been developed with the goal of improving the quality of university study programs. In this paper we compare the CDIO (Conceive, Design, Implement, Operate) and the work-integrated learning (WIL) initiatives based on recently completed WIL certifications at University West. Through a series of workshops, the CDIO standards are compared with the aspects and criteria of the WIL certification guidelines, to identify overlapping areas and differences between the two initiatives. The results show that both initiatives overlap but also differ in several aspects. These differences could be useful to strengthen the WIL certification process at University West as well as clarifying the connection between CDIO and work-integrated learning.  

1 - 12 av 12
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