umu.sePublikationer
Ändra sökning
Avgränsa sökresultatet
1234 51 - 100 av 168
RefereraExporteraLänk till träfflistan
Permanent länk
Referera
Referensformat
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annat format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annat språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf
Träffar per sida
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sortering
  • Standard (Relevans)
  • Författare A-Ö
  • Författare Ö-A
  • Titel A-Ö
  • Titel Ö-A
  • Publikationstyp A-Ö
  • Publikationstyp Ö-A
  • Äldst först
  • Nyast först
  • Skapad (Äldst först)
  • Skapad (Nyast först)
  • Senast uppdaterad (Äldst först)
  • Senast uppdaterad (Nyast först)
  • Disputationsdatum (tidigaste först)
  • Disputationsdatum (senaste först)
  • Standard (Relevans)
  • Författare A-Ö
  • Författare Ö-A
  • Titel A-Ö
  • Titel Ö-A
  • Publikationstyp A-Ö
  • Publikationstyp Ö-A
  • Äldst först
  • Nyast först
  • Skapad (Äldst först)
  • Skapad (Nyast först)
  • Senast uppdaterad (Äldst först)
  • Senast uppdaterad (Nyast först)
  • Disputationsdatum (tidigaste först)
  • Disputationsdatum (senaste först)
Markera
Maxantalet träffar du kan exportera från sökgränssnittet är 250. Vid större uttag använd dig av utsökningar.
  • 51.
    Ibidunmoye, Olumuyiwa
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Metsch, Thijs
    Intel Labs Europe, Collingstown Industrial Park, Leixlip, Ireland.
    Bayon-Molino, Victor
    Intel Labs Europe, Collingstown Industrial Park, Leixlip, Ireland.
    Elmroth, Erik
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Performance Anomaly Detection using Datacenter Landscape Graphs2017Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    The migration of mission-critical workloads to the cloud and the automation of various aspects of datacenter management is contributing to the evolution of software-defined infrastructures. One implication of this evolution is that the composition (both physical and virtual) and logical topology of datacenters is becoming even more dynamic. Identification of performance problems (e.g.\ bottlenecks) in such environments needs to be done with awareness of this dynamic topology to understand the impact of dependencies among components. A technique is introduced that a) employs expert knowledge to identify bottleneck components using associated performance metrics, and b) utilizes dynamic dependencies to rank problem components in order to facilitate diagnosis efforts. The technique is demonstrated experimentally on an OpenStack testbed with realistic fault injection. Results of experiment case studies show that the technique is able to correctly detect and rank problem nodes. 

  • 52.
    Ibidunmoye, Olumuyiwa
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Metsch, Thijs
    Intel Labs Europe, Ireland.
    Elmroth, Erik
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Real-time Detection of Performance Anomalies for Cloud Services2016Ingår i: 2016 IEEE/ACM 24th International Symposium on Quality of Service (IWQoS 2016), IEEE Communications Society, 2016, s. 164-165Konferensbidrag (Refereegranskat)
    Abstract [en]

    We propose two adaptive techniques for detecting anomalies in real-time service performance measurements. The techniques yielded low false alarm rates when evaluated on multiple time-series from the Yahoo! Webscope anomaly detection traces. 

  • 53.
    Ibidunmoye, Olumuyiwa
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Moghadam, Mahshid Helali
    Department of Computer Engineering, University of Kashan.
    Lakew, Ewnetu Bayuh
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Elmroth, Erik
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Adaptive Service Performance Control using Cooperative Fuzzy Reinforcement Learning in Virtualized Environments2017Ingår i: UCC '17 Proceedings of the10th International Conference on Utility and Cloud Computing, IEEE/ACM , 2017, s. 19-28Konferensbidrag (Refereegranskat)
    Abstract [en]

    Designing efficient control mechanisms to meet strict performance requirements with respect tochanging workload demands without sacrificing resource efficiency remains a challenge in cloudinfrastructures. A popular approach is fine-grained resource provisioning via auto-scaling mechanisms that rely on either threshold-based adaptation rules or sophisticated queuing/control-theoretic models. While it is difficult at design time to specify optimal threshold rules, it is even more challenging inferring precise performance models for the multitude of services. Recently, reinforcement learning have been applied to address this challenge. However, such approaches require many learning trials to stabilize at the beginning and when operational conditions vary thereby limiting their application under dynamic workloads. To this end, we extend the standard reinforcement learning approach in two ways: a) we formulate the system state as a fuzzy space and b) exploit a set of cooperative agents to explore multiple fuzzy states in parallel to speed up learning. Through multiple experiments on a real virtualized testbed, we demonstrate that our approach converges quickly, meets performance targets at high efficiency without explicit service models.

  • 54. Ilyushkin, Alexey
    et al.
    Ali-Eldin, Ahmed
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap. UMass, Amherst.
    Herbst, Nikolas
    Bauer, Andre
    Papadopoulos, Alessandro V.
    Epema, Dick
    Iosup, Alexandru
    An Experimental Performance Evaluation of Autoscalers for Complex Workflows2018Ingår i: ACM Transactions on Modeling and Performance Evaluation of Computing Systems, ISSN 2376-3639, Vol. 3, nr 2, artikel-id 8Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Elasticity is one of the main features of cloud computing allowing customers to scale their resources based on the workload. Many autoscalers have been proposed in the past decade to decide on behalf of cloud customers when and how to provision resources to a cloud application based on the workload utilizing cloud elasticity features. However, in prior work, when a new policy is proposed, it is seldom compared to the state-of-the-art, and is often compared only to static provisioning using a predefined quality of service target. This reduces the ability of cloud customers and of cloud operators to choose and deploy an autoscaling policy, as there is seldom enough analysis on the performance of the autoscalers in different operating conditions and with different applications. In our work, we conduct an experimental performance evaluation of autoscaling policies, using as application model workflows, a popular formalism for automating resource management for applications with well-defined yet complex structures. We present a detailed comparative study of general state-of-the-art autoscaling policies, along with two new workflow-specific policies. To understand the performance differences between the seven policies, we conduct various experiments and compare their performance in both pairwise and group comparisons. We report both individual and aggregated metrics. As many workflows have deadline requirements on the tasks, we study the effect of autoscaling on workflow deadlines. Additionally, we look into the effect of autoscaling on the accounted and hourly based charged costs, and we evaluate performance variability caused by the autoscaler selection for each group of workflow sizes. Our results highlight the trade-offs between the suggested policies, how they can impact meeting the deadlines, and how they perform in different operating conditions, thus enabling a better understanding of the current state-of-the-art.

  • 55. Ilyushkin, Alexey
    et al.
    Ali-Eldin, Ahmed
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Herbst, Nikolas
    Papadopoulos, Alessandro
    Ghit, Bogdan
    Epema, Dick
    Iosup, Alexandru
    An experimental performance evaluation of autoscaling policies for complex workflows2017Ingår i: Proceedings of the 8th ACM/SPEC on International Conference on Performance Engineering (ICPE '17), ACM Digital Library, 2017, s. 75-86Konferensbidrag (Övrigt vetenskapligt)
  • 56.
    Ingeson, Martin
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Blusi, Madeleine
    Umeå universitet, Medicinska fakulteten, Institutionen för samhällsmedicin och rehabilitering.
    Nieves, Juan Carlos
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Microsoft Hololens: A mHealth Solution for Medication Adherence2019Ingår i: Artificial Intelligence in Health: First International Workshop, AIH 2018, Stockholm, Sweden, 13-14 July, 2018, Revised Selected Papers / [ed] Koch F. et al., Springer, 2019, s. 99-115Konferensbidrag (Refereegranskat)
    Abstract [en]

    The aim of this paper is to introduce a smart mHealth application based on the augmented reality (AR)-paradigm that can support patients with common problems, related to management of their medication. This smart mHealth application is designed and implemented as a medication coach intelligent agent, called Medication Coach Intelligent Agent (MCIA). The MCIA has to manage different types of information such as the medication plan (medication regime) of the patients, medication restrictions, as well as the patient’s preferences and sensor input data from an AR-headset. Considering all this information, the MCIA leads with holistic decisions in order to offer personalized and unobtrusive interventions, in an autonomous way, to the patients. From a long-term perspective, the MCIA should also evaluate its performance over time and adapt in order to improve its interventions with the patients. To show the feasibility of our approach, a proof-of-concept prototype was implemented and evaluated. In this proof-of-concept prototype, the MCIA has been embodied as a smart augmented reality (AR)-mHealth application in the settings of a Microsoft HoloLens. The results show a high potential for using the MCIA in real settings.

  • 57.
    Ingeson, Martin
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Blusi, Madeleine
    Umeå universitet, Medicinska fakulteten, Institutionen för samhällsmedicin och rehabilitering.
    Nieves, Juan Carlos
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Smart augmented reality mHealth for medication adherence2018Ingår i: AIH 2018: Joint Workshop on AI in Health / [ed] Bichindaritz et.al ., 2018Konferensbidrag (Refereegranskat)
    Abstract [en]

    The aim of this paper is to introduce a smart mHealth applicationbased on the augmented reality (AR)-paradigm that can support patients with common problems, related to management of their medication. This smart mHealth application is designed and implemented as a medication coach intelligent agent, called Medication Coach Intelligent Agent (MCIA). TheMCIA will have to manage different types of information such as the medication plan (medication regime) of the patients, medication restrictions, as well as the patient’s preferences andsensor input data from an AR-headset. Considering all this information, theMCIA leads with holistic decisions in order to offer personalized and unobtrusive inter-ventions, in an autonomous way, to the patients. From a long term perspective, the MCIAshould also evaluate its performance over time and adapt in order to improve its interventions with the patients. To show the feasibility of our approach,a proof-of-concept prototype was implemented and evaluated. The results showa high potential for using theMCIAin real settings.

  • 58.
    Jacobsson, Markus
    et al.
    Indiana University, USA.
    Stolterman, Erik
    Umeå universitet, Samhällsvetenskapliga fakulteten, Institutionen för informatik.
    Wetzel, S
    Yang, L
    Love and authentication2008Ingår i: Proceedings of ACM CHI 2008 Conference on Human Factors in Computing Systems, 2008, s. 197-200Konferensbidrag (Refereegranskat)
  • 59.
    Jansson, Emil
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    SharePoint Online: Arbeta bland molnen2016Självständigt arbete på grundnivå (högskoleexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Idag är det allt fler företag som väljer molnlösningar framför ”on premise lösningar” därför det för många företag blir mer lönsamt än en traditionell lösning för IT-infrastrukturen. SharePoint Online (SPO) tillsammans med Microsoft Office 365 är ett sådant verktyg. Rapporten behandlar uppbyggnaden av en webbplattformslösning för det fiktiva företaget K800, SPO valdes eftersom SPO är en kollaborativ webbplattform med många olika användningsområden och funktioner som hjälper företag att samarbeta online. SPO har ett enkelt sätt att administrera konton och användare, man får gott om lagringsutrymme som kan utökas. Uppdateringarna sker per automatik och utan att en administratör behöver göra en fysisk insats. De anställda har också en accesspunkt oavsett var de befinner sig oberoende av vilken enhet de använder sig av, och företaget betalar bara för de licenser man använder sig av. I SPO så byggdes en gemensam webbplats upp för internt bruk där användarna kan använda sig av sidor och funktioner beroende på den behörighetsnivå de blivit tilldelade. SPO kan kännas svårt till en början, men tack vare all material på Internet så går det att lära sig själv. Det uppstod några problem och svårigheter på vägen men tack vare Microsofts många Supportteam och andra nämnda så kunde felen avhjälpas och det var möjligt att leverera en färdigutvecklad webbplattform till K800.

  • 60.
    Jernberg, Johan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Metoder för att sända meddelanden från QT Systems fastighetssystem till smarta telefoner2016Självständigt arbete på grundnivå (yrkesexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Företag har länge kunnat nå ut med information till kunder via traditionella metoder så som sms och e-post. I och med den stora populariteten hos smarta telefoner och sociala medier har information nu blivit extra viktigt. Med detta har det även kommit nyare sätt för företag att kommunicera med sina kunder så som via push-notifikationer till smarta telefoner och webbläsare eller via sociala medier.

    Projektet beställdes av QT Systems och hade som syfte att ge företaget en bättre inblick i vad de har för möjligheter när det gäller att nå ut med information till deras kunder. Målet med projektet var att finna den metod som bör passa bäst för att just QT Systems fastighetssystem ska kunna notifiera deras användare om olika händelser och att kunna visa att denna går att implementera i detta system.

    Under arbetets gång bestämdes det att push-notifikationer till en native app skulle vara den bästa lösningen. Det har även gjorts ett ”proof-of-concept” som visar att den valda metoden kommer gå att implementera i QT Systems fastighetssystem och åtminstone nå ut till smarta telefoner som har Android eller iOS som operativsystem.

  • 61.
    Kallin Westin, Lena
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Missing data and the preprocessing perceptron2004Rapport (Övrigt vetenskapligt)
    Abstract [en]

    In this paper, several ways to handle missing data, e.g. removing cases, mean imputation, and multiple imputation, are described and discussed. The Pima-Indians-Diabetes data set is used as a case study. This particular data set is interesting to use since it has not been obvious to all users that it actually contains a substantial amount of missing data. The data set is described in detail and the methods for coping with missing data mentioned in the text is applied on the data set.

    The preprocessing perceptron is used to train decision support systems on the data sets. A sketch of a way to impute missing data using the preprocessing perceptron is also proposed and discussed. The accuracy of the trained decision support systems, at the optimal efficiency point, lied in the interval 76-82% for the different methods. The highest values were obtained when all missing data cases were removed both from the test and the training set. This is, however, not a good way to handle missing data since the resulting decision support system is biased. Furthermore it will not be able to handle missing data when used on real data in the future. The results of the remaining methods were surprisingly similar, a reason for this might be that the data set used is rather large. Differences between methods would probably be larger in a smaller data set with larger amount of missing data.

  • 62.
    Kampik, Timotheus
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Empathic Agents: A Hybrid Normative/Consequentialistic Approach2019Ingår i: AAMAS 2019, ASSOC COMPUTING MACHINERY , 2019, s. 2423-2425Konferensbidrag (Refereegranskat)
    Abstract [en]

    Complex information systems operate with increasing degrees of autonomy. Consequently, such systems should not only optimize for simple metrics (like clicks and views) that reflect the system provider's preferences but also consider norms or rules, as well as the preferences of other agents that are affected by the systems' actions. As a means to achieve such behavior, we propose the design and development of empathic agents that use a mixed rule/utility-based approach when deciding on how to act, considering both their own and others' utility functions. The agents make use of formal argumentation to reach an agreement on how to act in case of inconsistent beliefs. A promising domain for applying our empathic agents is recommender systems.

  • 63. Karakostas, Vasileios
    et al.
    Goumas, Georgios
    Bayuh Lakew, Ewnetu
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Elmroth, Erik
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Gerangelos, Stefanos
    Kolberg, Simon
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Nikas, Konstantinos
    Psomadakis, Stratos
    Siakavaras, Dimitrios
    Svärd, Petter
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Koziris, Nectarios
    Efficient Resource Management for Data Centers: The ACTiCLOUD Approach2018Ingår i: 2018 International conference on embedded computer systems: architectures, modeling, and simulation (SAMOS XVIII) / [ed] Mudge T., Pnevmatikatos D.N., Association for Computing Machinery (ACM), 2018, s. 244-246Konferensbidrag (Refereegranskat)
    Abstract [en]

    Despite their proliferation as a dominant computing paradigm, cloud computing systems lack effective mechanisms to manage their vast resources efficiently. Resources are stranded and fragmented, limiting cloud applicability only to classes of applications that pose moderate resource demands. In addition, the need for reduced cost through consolidation introduces performance interference, as multiple VMs are co-located on the same nodes. To avoid such issues, current providers follow a rather conservative approach regarding resource management that leads to significant underutilization. ACTiCLOUD is a three-year Horizon 2020 project that aims at creating a novel cloud architecture that breaks existing scale-up and share-nothing barriers and enables the holistic management of physical resources, at both local and distributed cloud site levels. This extended abstract provides a brief overview of the resource management part of ACTiCLOUD, focusing on the design principles and the components.

  • 64.
    Khan, Muhammad Sikandar Lal
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Presence through actions: theories, concepts, and implementations2017Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    During face-to-face meetings, humans use multimodal information, including verbal information, visual information, body language, facial expressions, and other non-verbal gestures. In contrast, during computer-mediated-communication (CMC), humans rely either on mono-modal information such as text-only, voice-only, or video-only or on bi-modal information by using audiovisual modalities such as video teleconferencing. Psychologically, the difference between the two lies in the level of the subjective experience of presence, where people perceive a reduced feeling of presence in the case of CMC. Despite the current advancements in CMC, it is still far from face-to-face communication, especially in terms of the experience of presence.

    This thesis aims to introduce new concepts, theories, and technologies for presence design where the core is actions for creating presence. Thus, the contribution of the thesis can be divided into a technical contribution and a knowledge contribution. Technically, this thesis details novel technologies for improving presence experience during mediated communication (video teleconferencing). The proposed technologies include action robots (including a telepresence mechatronic robot (TEBoT) and a face robot), embodied control techniques (head orientation modeling and virtual reality headset based collaboration), and face reconstruction/retrieval algorithms. The introduced technologies enable action possibilities and embodied interactions that improve the presence experience between the distantly located participants. The novel setups were put into real experimental scenarios, and the well-known social, spatial, and gaze related problems were analyzed.

    The developed technologies and the results of the experiments led to the knowledge contribution of this thesis. In terms of knowledge contribution, this thesis presents a more general theoretical conceptual framework for mediated communication technologies. This conceptual framework can guide telepresence researchers toward the development of appropriate technologies for mediated communication applications. Furthermore, this thesis also presents a novel strong concept – presence through actions - that brings in philosophical understandings for developing presence- related technologies. The strong concept - presence through actions is an intermediate-level knowledge that proposes a new way of creating and developing future 'presence artifacts'. Presence- through actions is an action-oriented phenomenological approach to presence that differs from traditional immersive presence approaches that are based (implicitly) on rationalist, internalist views.

  • 65.
    Khan, Muhammad Sikandar Lal
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Halawani, Alaa
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik. Computer Engineering Department, Palestine Polytechnic University, Hebron 90100, Palestine.
    ur Réhman, Shafiq
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Li, Haibo
    Action Augmented Real Virtuality Design for Presence2018Ingår i: IEEE Transactions on Cognitive and Developmental Systems, ISSN 2379-8920, Vol. 10, nr 4, s. 961-972Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This paper addresses the important question of how to design a video teleconferencing setup to increase the experience of spatial and social presence. Traditional video teleconferencing setups are lacking in presenting the nonverbal behaviors that humans express in face-to-face communication, which results in decrease in presence-experience. In order to address this issue, we first present a conceptual framework of presence for video teleconferencing. We introduce a modern presence concept called real virtuality and propose a new way of achieving this based on body or artifact actions to increase the feeling of presence, and we named this concept presence through actions. Using this new concept, we present the design of a novel action-augmented real virtuality prototype that considers the challenges related to the design of an action prototype, action embodiment, and face representation. Our action prototype is a telepresence mechatronic robot (TEBoT), and action embodiment is through a head-mounted display (HMD). The face representation solves the problem of face occlusion introduced by the HMD. The novel combination of HMD, TEBoT, and face representation algorithm has been tested in a real video teleconferencing scenario for its ability to solve the challenges related to spatial and social presence. We have performed a user study where the invited participants were requested to experience our novel setup and to compare it with a traditional video teleconferencing setup. The results show that the action capabilities not only increase the feeling of spatial presence but also increase the feeling of social presence of a remote person among local collaborators.

  • 66.
    Khan, Muhammad Sikandar Lal
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    ur Réhman, Shafiq
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik. University of East London, United Kingdom.
    Mi, Yongcui
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Naeem, Usman
    University of East London, United Kingdom.
    Beskow, Jonas
    The Royal Institute of Technology (KTH), Stockholm, Sweden.
    Li, Haibo
    The Royal Institute of Technology (KTH), Stockholm, Sweden.
    Moveable facial features in a Social Mediator2017Ingår i: Intelligent Virtual Agents: IVA 2017 / [ed] Beskow J., Peters C., Castellano G., O'Sullivan C., Leite I., Kopp S., Springer London, 2017, s. 205-208Konferensbidrag (Refereegranskat)
    Abstract [en]

    A brief display of facial features based behavior has a majorimpact on personality perception in human-human communications.Creating such personality traits and representations in a social robot isa challenging task. In this paper, we propose an approach for a roboticface presentation based on moveable 2D facial features and present acomparative study when a synthesized face is projected using three setups;1) 3D mask, 2) 2D screen, and 3) our 2D moveable facial featurebased visualization. We found that robot’s personality and character ishighly influenced by the projected face quality as well as the motion offacial features.

  • 67.
    Khan, Muhammad Sikandar Lal
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    ur Réhman, Shafiq
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik. University of East London, London, England.
    Söderström, Ulrik
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Halawani, Alaa
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Li, Haibo
    Face-off: a Face Reconstruction Technique for Virtual Reality (VR) Scenarios2016Ingår i: Computer Vision: ECCV 2016 Workshops / [ed] Hua G., Jégou H., Springer, 2016, Vol. 9913, s. 490-503Konferensbidrag (Refereegranskat)
    Abstract [en]

    Virtual Reality (VR) headsets occlude a significant portion of human face. The real human face is required in many VR applications, for example, video teleconferencing. This paper proposes a wearable camera setup-based solution to reconstruct the real face of a person wearing VR headset. Our solution lies in the core of asymmetrical principal component analysis (aPCA). A user-specific training model is built using aPCA with full face, lips and eye region information. During testing phase, lower face region and partial eye information is used to reconstruct the wearer face. Online testing session consists of two phases, i) calibration phase and ii) reconstruction phase. In former, a small calibration step is performed to align test information with training data, while the later uses half face information to reconstruct the full face using aPCA-based trained-data. The proposed approach is validated with qualitative and quantitative analysis.

  • 68.
    Klein, Cristian
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Maggio, Martina
    Lund University.
    Årzén, Karl-Erik
    Lund University.
    Hernández-Rodriguez, Francisco
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Brownout: Building More Robust Cloud Applications2014Ingår i: 36th International Conference on Software Engineering (ICSE 2014), ACM Digital Library, 2014, s. 700-711Konferensbidrag (Refereegranskat)
    Abstract [en]

    Self-adaptation is a first class concern for cloud applications, which should be able to withstand diverse runtime changes. Variations are simultaneously happening both at the cloud infrastructure level - for example hardware failures - and at the user workload level - flash crowds. However, robustly withstanding extreme variability, requires costly hardware over-provisioning. In this paper, we introduce a self-adaptation programming paradigm called brownout. Using this paradigm, applications can be designed to robustly withstand unpredictable runtime variations, without over-provisioning. The paradigm is based on optional code that can be dynamically deactivated through decisions based on control theory. We modified two popular web application prototypes - RUBiS and RUBBoS - with less than 170 lines of code, to make them brownout-compliant. Experiments show that brownout self-adaptation dramatically improves the ability to withstand flash-crowds and hardware failures.

  • 69.
    Klein, Cristian
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Maggio, Martina
    Lund University.
    Årzén, Karl-Erik
    Lund University.
    Hernández-Rodriguez, Francisco
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Introducing Service-level Awareness in the Cloud2013Ingår i: Proceedings of the 4th annual Symposium on Cloud Computing, Association for Computing Machinery (ACM), 2013Konferensbidrag (Refereegranskat)
  • 70.
    Klein, Cristian
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Maggio, Martina
    Lund University.
    Årzén, Karl-Erik
    Lund University.
    Hernández-Rodriguez, Francisco
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Introducing Service-level Awareness in the Cloud2013Rapport (Övrigt vetenskapligt)
    Abstract [en]

    Resource allocation in clouds is mostly done assuming hard requirements, applications either receive the requested resources or fail. Given the dynamic nature of workloads, guaranteeing on-demand allocations requires large spare capacity. Hence, one cannot have a system that is both reliable and efficient.

    To solve this issue, we introduce Service-Level (SL) awareness in clouds, assuming applications contain some optional code that can be dynamically deactivated as needed. First, we design a model for such applications and synthesize a controller to decide when to execute the optional code and when to skip it. Then, we propose a Resource Manager (RM) that allocates resources to multiple SL-aware applications in a fair manner. We theoretically prove properties of the overall system using control and game theory.

    To show the practical applicability, we implemented SL-aware versions of RUBiS and RUBBoS with less than 170 lines of code. Experiments show that SL-awareness may enable a factor 8 improvement in withstanding flash-crowds or failures. SL-awareness opens up more flexibility in cloud resource management, which is why we encourage further research by publishing all source code.

  • 71.
    Klein, Cristian
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Maggio, Martina
    Lund University.
    Årzén, Karl-Erik
    Lund University.
    Hernández-Rodriguez, Francisco
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Resource management for service level aware cloud applications2013Konferensbidrag (Refereegranskat)
    Abstract [en]

    Resource allocation in clouds is mostly done assuming hard requirements, time-sensitive applications either receive the requested resources or fail. Given the dynamic nature of workloads, guaranteeing on-demand allocations requires large spare capacity. Hence, one cannot have a system that is both reliable and efficient.

    To mitigate this issue, we introduce service-level awareness in clouds, assuming applications contain some optional code that can be dynamically deactivated as needed. We propose a resource manager that allocates resources to multiple service-level-aware applications in a fair manner. To show the practical applicability, we implemented service-level-aware versions of RUBiS and RUBBoS, two popular cloud benchmarks, together with our resource manager. Experiments show that service-level awareness helps in withstanding flash-crowds or failures, opening up more flexibility in cloud resource management.

  • 72.
    Klein, Cristian
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Papadopoulos, Alessandro Vittorio
    Lund University, Sweden.
    Dellkrantz, Manfred
    Lund University, Sweden.
    Dürango, Jonas
    Lund University, Sweden.
    Maggio, Martina
    Lund University.
    Årzén, Karl-Erik
    Lund University.
    Hernández-Rodriguez, Francisco
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Elmroth, Erik
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Improving Cloud Service Resilience using Brownout-Aware Load-Balancing2014Ingår i: 2014 IEEE 33RD INTERNATIONAL SYMPOSIUM ON RELIABLE DISTRIBUTED SYSTEMS (SRDS), IEEE Computer Society, 2014, s. 31-40Konferensbidrag (Refereegranskat)
    Abstract [en]

    We focus on improving resilience of cloud services (e.g., e-commerce website), when correlated or cascading failures lead to computing capacity shortage. We study how to extend the classical cloud service architecture composed of a load-balancer and replicas with a recently proposed self-adaptive paradigm called brownout. Such services are able to reduce their capacity requirements by degrading user experience (e.g., disabling recommendations).

    Combining resilience with the brownout paradigm is to date an open practical problem. The issue is to ensure that replica self-adaptivity would not confuse the load-balancing algorithm, overloading replicas that are already struggling with capacity shortage. For example, load-balancing strategies based on response times are not able to decide which replicas should be selected, since the response times are already controlled by the brownout paradigm.

    In this paper we propose two novel brownout-aware load-balancing algorithms. To test their practical applicability, we extended the popular lighttpd web server and load-balancer, thus obtaining a production-ready implementation. Experimental evaluation shows that the approach enables cloud services to remain responsive despite cascading failures. Moreover, when compared to Shortest Queue First (SQF), believed to be near-optimal in the non-adaptive case, our algorithms improve user experience by 5%, with high statistical significance, while preserving response time predictability.

  • 73. Kleyko, Denis
    et al.
    Osipov, Evgeny
    Wiklund, Urban
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper.
    A Hyperdimensional Computing Framework for Analysis of Cardiorespiratory Synchronization During Paced Deep Breathing2019Ingår i: IEEE Access, E-ISSN 2169-3536, Vol. 7, s. 34403-34415Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Autonomic function during deep breathing (DB) is normally scored based on the assumption that the heart rate is synchronized with the breathing. We have observed individuals with subtle arrhythmias during DB, where an autonomic function cannot be evaluated. This paper presents a novel method for analyzing cardiorespiratory synchronization: feature-based analysis of the similarity between heart rate and respiration using the principles of hyperdimensional computing. Heart rate and respiration signals were modeled using Fourier series analysis. Three feature variables were derived and mapped to binary vectors in a high-dimensional space. Using both synthesized data and recordings from patients/healthy subjects, the similarity between the feature vectors was assessed using Hamming distance (high-dimensional space), Euclidean distance (original space), and with a coherence-based index. Methods were evaluated via the classification of the similarity indices into three groups. The distance-based methods achieved good separation of signals into classes with different degrees of cardiorespiratory synchronization, also providing identification of patients with low cardiorespiratory synchronization but high values of conventional DB scores. Moreover, binary high-dimensional vectors allowed an additional analysis of the obtained Hamming distance. Feature-based similarity analysis using hyperdimensional computing is capable of identifying signals with low cardiorespiratory synchronization during DB due to arrhythmias. Vector-based similarity analysis could be applied to other types of feature variables than based on spectral analysis. The proposed methods for robustly assessing cardiorespiratory synchronization during DB facilitate the identification of individuals where the evaluation of the autonomic function is problematic or even impossible, thus increasing the correctness of the conventional DB scores.

  • 74.
    Krzywda, Jakub
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Analysing, modelling and controlling power-performance tradeoffs in data center infrastructures2017Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    The aim of this thesis is to analyse the power-performance tradeoffs in datacenter servers, create models that capture these tradeoffs, and propose controllers to optimise the use of data center infrastructures taking the tradeoffs into consideration. The main research problem that we investigate in this thesis is how to increase the power efficiency of data center servers taking into account the power-performance tradeoffs.

    The main cause for this research is the massive power consumption of data centers that is a concern both from the financial and environmental footprint perspectives. Irrespectively of the approaches taken to enhance data center power efficiency, substantial reductions in the power consumption of data center servers easily lead to performance degradation of hosted applications, which causes customers dissatisfaction. Therefore, it is crucial for the data center operators to understand and control the power-performance tradeoffs.

    The research methods used in this thesis include experiments on real testbeds, applying statistical methods to create power-performance models, development of various optimisation techniques to improve the energy-efficiency of servers, and simulations to evaluate proposed solutions at scale.

    As a result of the research presented in this thesis, we propose taxonomies for selected aspects of data center configurations, events, management actions, and monitored metrics. We discuss the relationships between these elements and to support the analysis present results from a set of testbed experiments.We show limitations in the applicability of various data center management actions, including Dynamic Voltage Frequency Scaling (DVFS), Running Average Power Limit (RAPL), CPU Pinning, horizontal and vertical scaling. Finally, we propose a power budgeting controller that minimizes the performance degradation while enforcing the power limits.

    The outcomes of this thesis can be used by the data center operators to improve the energy-efficiency of servers and reduce the overall power consumption with minimized performance degradation. Moreover, the software artifacts including virtual machine images, scripts, and simulator are available online.

    Future work includes further investigation of the problem of graceful performance degradation under power limits, incorporating multi-layer applications spread among several servers and load balancing controller.

  • 75.
    Krzywda, Jakub
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    May the power be with you: managing power-performance tradeoffs in cloud data centers2019Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    The overall goal of the work presented in this thesis was to find ways of managing power-performance tradeoffs in cloud data centers. To this end, the relationships between the power consumption of data center servers and the performance of applications hosted in data centers are analyzed, models that capture these relationships are developed, and controllers to optimize the use of data center infrastructures are proposed.

    The studies were motivated by the massive power consumption of modern data centers, which is a matter of significant financial and environmental concern. Various strategies for improving the power efficiency of data centers have been proposed, including server consolidation, server throttling, and power budgeting. However, no matter what strategy is used to enhance data center power efficiency, substantial reductions in the power consumption of data center servers can easily degrade the performance of hosted applications, causing customer dissatisfaction. It is therefore crucial for data center operators to understand and control power-performance tradeoffs.

    The research methods used in this work include experiments on real testbeds, the application of statistical methods to create power-performance models, development of various optimization techniques to improve the power efficiency of servers, and simulations to evaluate the proposed solutions at scale.

    This thesis makes multiple contributions. First, it introduces taxonomies for various aspects of data center configuration, events, management actions, and monitored metrics. We discuss the relationships between these elements and support our analysis with results from a set of testbed experiments. We demonstrate limitations on the usefulness of various data center management actions for controlling power consumption, including Dynamic Voltage Frequency Scaling (DVFS) and Running Average Power Limit (RAPL). We also demonstrate similar limitations on common measures for controlling application performance, including variation of operating system scheduling parameters, CPU pinning, and horizontal and vertical scaling. Finally, we propose a set of power budgeting controllers that act at the application, server, and cluster levels to minimize performance degradation while enforcing power limits.

    The results and analysis presented in this thesis can be used by data center operators to improve the power-efficiency of servers and reduce overall operational costs while minimizing performance degradation. All of the software generated during this work, including controller source code, virtual machine images, scripts, and simulators, has been open-sourced.

  • 76.
    Krzywda, Jakub
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Ali-Eldin, A.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap. College of Information and Computer Sciences, University of Massachusetts Amherst.
    Wadbro, Eddie
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Östberg, Per-Olov
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Elmroth, Erik
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    ALPACA: Application Performance Aware Server Power Capping2018Ingår i: ICAC 2018: 2018 IEEE International Conference on Autonomic Computing (ICAC), Trento, Italy, September 3-7, 2018, IEEE Computer Society, 2018, s. 41-50Konferensbidrag (Refereegranskat)
    Abstract [en]

    Server power capping limits the power consumption of a server to not exceed a specific power budget. This allows data center operators to reduce the peak power consumption at the cost of performance degradation of hosted applications. Previous work on server power capping rarely considers Quality-of-Service (QoS) requirements of consolidated services when enforcing the power budget. In this paper, we introduce ALPACA, a framework to reduce QoS violations and overall application performance degradation for consolidated services. ALPACA reduces unnecessary high power consumption when there is no performance gain, and divides the power among the running services in a way that reduces the overall QoS degradation when the power is scarce. We evaluate ALPACA using four applications: MediaWiki, SysBench, Sock Shop, and CloudSuite’s Web Search benchmark. Our experiments show that ALPACA reduces the operational costs of QoS penalties and electricity by up to 40% compared to a non optimized system. 

  • 77.
    Krzywda, Jakub
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Ali-Eldin, Ahmed
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Carlson, Trevor E.
    Department of Information Technology, Uppsala University, SE-751 05 Uppsala, Sweden.
    Östberg, Per-Olov
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Elmroth, Erik
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Power-performance tradeoffs in data center servers: DVFS, CPUpinning, horizontal, and vertical scaling2018Ingår i: Future generations computer systems, ISSN 0167-739X, E-ISSN 1872-7115, Vol. 81, s. 114-128Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Dynamic Voltage and Frequency Scaling (DVFS), CPU pinning, horizontal, and vertical scaling, are four techniques that have been proposed as actuators to control the performance and energy consumption on data center servers. This work investigates the utility of these four actuators, and quantifies the power-performance tradeoffs associated with them. Using replicas of the German Wikipedia running on our local testbed, we perform a set of experiments to quantify the influence of DVFS, vertical and horizontal scaling, and CPU pinning on end-to-end response time (average and tail), throughput, and power consumption with different workloads. Results of the experiments show that DVFS rarely reduces the power consumption of underloaded servers by more than 5%, but it can be used to limit the maximal power consumption of a saturated server by up to 20% (at a cost of performance degradation). CPU pinning reduces the power consumption of underloaded server (by up to 7%) at the cost of performance degradation, which can be limited by choosing an appropriate CPU pinning scheme. Horizontal and vertical scaling improves both the average and tail response time, but the improvement is not proportional to the amount of resources added. The load balancing strategy has a big impact on the tail response time of horizontally scaled applications.

  • 78.
    Krzywda, Jakub
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Ali-Eldin, Ahmed
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap. 2College of Information and Computer Sciences, University of Massachusetts Amherst.
    Wadbro, Eddie
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Östberg, Per-Olov
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Elmroth, Erik
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Power Shepherd: Application Performance AwarePower ShiftingManuskript (preprint) (Övrigt vetenskapligt)
    Abstract [en]

    Constantly growing power consumption of data centers is a major concern from environmental and economical reasons. Current approaches to reduce the negative consequences of high power consumption focus on limiting the peak power consumption. During the high workload periods, power consumption of highly utilized servers is throttled in order to stay within the power budget. However, the peak power reduction affects performance of hosted applications and thus leads to Quality of Service violations. In this paper, we introduce Power Shepherd, a hierarchical system for application performance aware power shifting. Power Shepherd reduces the data center operational costs by redistributing the available power among applications hosted in the cluster. This is achieved by, assigning server power budgets by the cluster controller, enforcing these power budgets using Running Average Power Limit (RAPL), and prioritizing applications within each server by adjusting the CPU scheduling configuration. We implement a prototype of the proposed solution and evaluate it in a real testbed equipped with power meters and using representative cloud applications. Our experiments show that Power Shepherd has potential to manage a cluster consisting of thousands of servers and limit the increase of operational costs by a significant amount when the cluster power budget is limited and the system is overutilized. Finally, we identify some outstanding challenges regarding model sensitivity and the fact that this approach in its current form is not beneficial to be used in all situations, e.g., when the system is underutilized.

  • 79.
    Krzywda, Jakub
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Meyer, Vinicius
    Xavier, Miguel G.
    Ali-Eldin, Ahmed
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap. College of Information and Computer Sciences, University of Massachusetts Amherst.
    Östberg, Per-Olov
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    De Rose, Cesar A. F.
    Elmroth, Erik
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Modeling and Simulation of QoS-AwarePower Budgeting in Cloud Data CentersManuskript (preprint) (Övrigt vetenskapligt)
    Abstract [en]

    Power budgeting is a commonly employed solution to reduce the negative consequences of high power consumption of large scale data centers. While various power budgeting techniques and algorithms have been proposed at different levels of data center infrastructures to optimize the power allocation to servers and hosted applications, testing them has been challenging with no available simulation platform that enables such testing for different scenarios and configurations. To facilitate evaluation and comparison of such techniques and algorithms, we introduce a simulation model for Quality-of-Service aware power budgeting and its implementation in CloudSim. We validate the proposed simulation model against a deployment on a real testbed, showcase simulator capabilities, and evaluate its scalability.

  • 80.
    Krzywda, Jakub
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Tärneberg, William
    Dept. of Electrical and Information Technology, Lund University.
    Östberg, Per-Olov
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Kihl, Maria
    Dept. of Electrical and Information Technology, Lund University.
    Elmroth, Erik
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Telco Clouds: Modelling and Simulation2015Konferensbidrag (Refereegranskat)
  • 81.
    Krzywda, Jakub
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Östberg, Per-Olov
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Elmroth, Erik
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    A Sensor-Actuator Model for Data Center Optimization2015Ingår i: 2015 INTERNATIONAL CONFERENCE ON CLOUD AND AUTONOMIC COMPUTING (ICCAC), New York: IEEE Computer Society, 2015, s. 192-195Konferensbidrag (Refereegranskat)
    Abstract [en]

    Cloud data centers commonly use virtualization technologies to provision compute capacity with a level of indirection between virtual machines and physical resources. In this paper we explore the use of that level of indirection as a means for autonomic data center configuration optimization and propose a sensor-actuator model to capture optimization-relevant relationships between data center events, monitored metrics (sensors data), and management actions (actuators). The model characterizes a wide spectrum of actions to help identify the suitability of different actions in specific situations, and outlines what (and how often) data needs to be monitored to capture, classify, and respond to events that affect the performance of data center operations.

  • 82.
    Krzywda, Jakub
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Östberg, Per-Olov
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Elmroth, Erik
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    A Sensor-Actuator Model for Data Center Optimization2015Rapport (Övrigt vetenskapligt)
  • 83.
    Lakew, Ewnetu B.
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Klein, Cristian
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Hernandez-Rodriguez, Francisco
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Elmroth, Erik
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Performance-Based Service Differentiation in Clouds2015Ingår i: 2015 15th IEEE/ACM International Symposium on Cluster, Cloud and Grid Computing (CCGrid), IEEE conference proceedings, 2015, s. 505-514Konferensbidrag (Refereegranskat)
    Abstract [en]

    Due to fierce competition, cloud providers need to run their data-centers efficiently. One of the issues is to increase data-center utilization while maintaining applications' performance targets. Achieving high data-center utilization while meeting applications' performance is difficult, as data-center overload may lead to poor performance of hosted services. Service differentiation has been proposed to control which services get degraded. However, current approaches are capacity-based, which are oblivious to the observed performance of each service and cannot divide the available capacity among hosted services so as to minimize overall performance degradation. In this paper we propose performance-based service differentiation. In case enough capacity is available, each service is automatically allocated the right amount of capacity that meets its target performance, expressed either as response time or throughput. In case of overload, we propose two service differentiation schemes that dynamically decide which services to degrade and to what extent. We carried out an extensive set of experiments using different services -- interactive as well as non-interactive -- by varying the workload mixes of each service over time. The results demonstrate that our solution precisely provides guaranteed performance or service differentiation depending on available capacity.

  • 84.
    Lakew, Ewnetu. B.
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Klein, Cristian
    Hernandez-Rodriguez, Francisco
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Elmroth, Erik
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Tail Response Time Modeling and Control for Interactive Cloud ServicesManuskript (preprint) (Övrigt vetenskapligt)
  • 85.
    Lakew, Ewnetu Bayuh
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Autonomous cloud resource provisioning: accounting, allocation, and performance control2015Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    The emergence of large-scale Internet services coupled with the evolution of computing technologies such as distributed systems, parallel computing, utility computing, grid, and virtualization has fueled a movement toward a new resource provisioning paradigm called cloud computing. The main appeal of cloud computing lies in its ability to provide a shared pool of infinitely scalable computing resources for cloud services, which can be quickly provisioned and released on-demand with minimal effort. The rapidly growing interest in cloud computing from both the public and industry together with the rapid expansion in scale and complexity of cloud computing resources and the services hosted on them have made monitoring, controlling, and provisioning cloud computing resources at runtime into a very challenging and complex task. This thesis investigates algorithms, models and techniques for autonomously monitoring, controlling, and provisioning the various resources required to meet services’ performance requirements and account for their resource usage.

    Quota management mechanisms are essential for controlling distributed shared resources so that services do not exceed their allocated or paid-for budget. Appropriate cloud-wide monitoring and controlling of quotas must be exercised to avoid over- or under-provisioning of resources. To this end, this thesis presents new distributed algorithms that efficiently manage quotas for services running across distributed nodes.

    Determining the optimal amount of resources to meet services’ performance requirements is a key task in cloud computing. However, this task is extremely challenging due to multi-faceted issues such as the dynamic nature of cloud environments, the need for supporting heterogeneous services with different performance requirements, the unpredictable nature of services’ workloads, the non-triviality of mapping performance measurements into resources, and resource shortages. Models and techniques that can predict the optimal amount of resources needed to meet service performance requirements at runtime irrespective of variations in workloads are proposed. Moreover, different service differentiation schemes are proposed for managing temporary resource shortages due to, e.g., flash crowds or hardware failures.

    In addition, the resources used by services must be accounted for in order to properly bill customers. Thus, monitoring data for running services should be collected and aggregated to maintain a single global state of the system that can be used to generate a single bill for each customer. However, collecting and aggregating such data across geographical distributed locations is challenging because the management task itself may consume significant computing and network resources unless done with care. A consistency and synchronization mechanism that can alleviate this task is proposed.

  • 86.
    Lakew, Ewnetu Bayuh
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Cristian, Klein
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Francisco, Hernandez-Rodriguez
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Erik, Elmroth
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Towards faster response time models for vertical elasticity2014Ingår i: 2014 IEEE/ACM 7TH INTERNATIONAL CONFERENCE ON UTILITY AND CLOUD COMPUTING (UCC), 2014, s. 560-565Konferensbidrag (Refereegranskat)
    Abstract [en]

    Resource provisioning in cloud computing is typ- ically coarse-grained. For example, entire CPU cores may be allocated for periods of up to an hour. The Resource-as-a- Service cloud concept has been introduced to improve the efficiency of resource utilization in clouds. In this concept, resources are allocated in terms of CPU core fractions, with granularities of seconds. Such infrastructures could be created using existing technologies such as lightweight virtualization using LXC or by exploiting the Xen hypervisor’s capacity for vertical elasticity. However, performance models for de- termining how much capacity to allocate to each application are currently lacking. To address this deficit, we evaluate two performance models for predicting mean response times: the previously proposed queue length model and the novel inverse model. The models are evaluated using 3 applications under both open and closed system models. The inverse model reacted rapidly and remained stable even with targets as low as 0.5 seconds. 

  • 87.
    Lakew, Ewnetu Bayuh
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Lei, Xu
    School of Computing, Dublin City University, Ireland.
    Francisco, Hernandez-Rodriguez
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Erik, Elmroth
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Claus, Pahl
    School of Computing, Dublin City University, Ireland.
    A Tree-based Protocol for Enforcing Quotas in Clouds2014Ingår i: the IEEE 10th 2014 World Congress on Services (SERVICES 2014), IEEE Computer Society, 2014Konferensbidrag (Refereegranskat)
    Abstract [en]

    Services are more and more hosted on cloud nodes for enhancing their performance and increasing their availability. The virtually unlimited availability of resources enables service owners to consume resources without quantitative restrictions, paying only for what they consume. To avoid cost overrun, resource consumption must be controlled and capped when necessary.We present a distributed tree-based protocol to manage quotas in clouds that minimizes communication overhead and reduces the time required to inspect if a quota has been exhausted. Experimental evaluation shows that our protocol provides 42% more communication savings and is up to 15 times faster compared to a distributed baseline solution.

  • 88.
    Lakew, Ewnetu Bayuh
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Papadopoulos, Alessandro Vittorio
    Maggio, Martina
    Klein, Cristian
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Elmroth, Erik
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    KPI-agnostic Control for Fine-Grained Vertical Elasticity2017Ingår i: 2017 17TH IEEE/ACM INTERNATIONAL SYMPOSIUM ON CLUSTER, CLOUD AND GRID COMPUTING (CCGRID), IEEE , 2017, s. 589-598Konferensbidrag (Refereegranskat)
    Abstract [en]

    Applications hosted in the cloud have become indispensable in several contexts, with their performance often being key to business operation and their running costs needing to be minimized. To minimize running costs, most modern virtualization technologies such as Linux Containers, Xen, and KVM offer powerful resource control primitives for individual provisioning - that enable adding or removing of fraction of cores and/or megabytes of memory for as short as few seconds. Despite the technology being ready, there is a lack of proper techniques for fine-grained resource allocation, because there is an inherent challenge in determining the correct composition of resources an application needs, with varying workload, to ensure deterministic performance.

    This paper presents a control-based approach for the management of multiple resources, accounting for the resource consumption, together with the application performance, enabling fine-grained vertical elasticity. The control strategy ensures that the application meets the target performance indicators, consuming as less resources as possible. We carried out an extensive set of experiments using different applications – interactive with response-time requirements, as well as non-interactive with throughput desires – by varying the workload mixes of each application over time. The results demonstrate that our solution precisely provides guaranteed performance while at the same time avoiding both resource over- and under-provisioning.

  • 89.
    Lei, Xu
    et al.
    School of Computing, Dublin City University, Ireland.
    Lakew, Ewnetu Bayuh
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Claus, Pahl
    School of Computing, Dublin City University, Ireland.
    Resource State Monitoring of Service Transactions in Cloud Systems2014Ingår i: 2014 IEEE International Conference on Services Computing (SCC 2014), IEEE conference proceedings, 2014, s. 512-519Konferensbidrag (Refereegranskat)
    Abstract [en]

    In cloud systems, services constituting a transaction may spread over a large number of servers or clusters. Theoretically, these services could consume cloud resources unlimitedly. To avoid financial loss due to resource overuse, clouds have to monitor the state of resources consumed by the services – collect values of consumption, and evaluate whether the combined usage of resources has excessed a pre-defined upper bound or not. The distributed nature of the services introduces a challenge to the monitoring system on how to summarise distributed state information with low cost. We present our resource state monitoring solution to capture the challenge introduced by services hosted in clouds. Our solution tracks the resource consumed by each service constituting a transaction individually whilst ensures the whole transaction does not overuse the allocated resource. It improves availability by avoiding single points of failure, and achieves scalability by minimising message exchanges.We performed experimental analyses that indicate this work can provide an inexpensive resource monitoring solution for transactions in clouds.

  • 90.
    Li, Bo
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Pushing edge detection to the limit: towards building semantic features for human emotion recognition2013Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
  • 91.
    Li, Wubin
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Virtual Machine Placement in Cloud Environments2012Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    With the emergence of cloud computing, computing resources (i.e., networks, servers, storage, applications, and services) are provisioned as metered on-demand services over networks, and can be rapidly allocated and released with minimal management effort. In the cloud computing paradigm, the virtual machine is one of the most commonly used resource carriers in which business services are encapsulated. Virtual machine placement optimization, i.e., finding optimal placement schemes for virtual machines, and reconfigurations according to the changes of environments, become challenging issues.

    The primary contribution of this licentiate thesis is the development and evaluation of our combinatorial optimization approaches to virtual machine placement in cloud environments. We present modeling for dynamic cloud scheduling via migration of virtual machines in multi-cloud environments, and virtual machine placement for predictable and time-constrained peak loads in single-cloud environments. The studied problems are encoded in a mathematical modeling language and solved using a linear programming solver. In addition to scientific publications, this work also contributes in the form of software tools (in EU-funded project OPTIMIS) that demonstrate the feasibility and characteristics of the approaches presented.

  • 92.
    Lindgren, Helena
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Baskar, Jayalakshmi
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Guerrero, Esteban
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Nieves, Juan Carlos
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Nilsson, Ingeborg
    Umeå universitet, Medicinska fakulteten, Institutionen för samhällsmedicin och rehabilitering.
    Yan, Chunli
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Computer-Supported Assessment for Tailoring Assistive Technology2016Ingår i: DH'16: PROCEEDINGS OF THE 2016 DIGITAL HEALTH CONFERENCE, New York: Association for Computing Machinery (ACM), 2016, s. 1-10Konferensbidrag (Refereegranskat)
    Abstract [en]

    The main purpose of assistive technology is to support an individual's daily activities, in order to increase ability, autonomy, relatedness and quality of life. The aim for the work presented in this article is to develop automated methods to tailor the behavior of the assistive technology for the purpose to provide just-in-time, adaptive interventions targeting multiple domains. This requires methods for representing and updating the user model, including goals, preferences, abilities, activity and its situation. We focus the assessment and intervention tasks typically performed by therapists and provide knowledge-based technology for supporting the process. A formative evaluation study was conducted as a part of a participatory action research process, involving two rehabilitation experts, two young individuals and one senior individual as end-user participants, in addition to knowledge engineers. The main contribution of this work is a theory-based method for assessing the individual's goals, preferences, abilities and motives, which is used for building a holistic user model. The user model is continuously updated and functions as the base for tailoring the system's assistive behavior during intervention and follow-up.

  • 93.
    Lu, Zhihan
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik. Chinese Academy of Science, China.
    Halawani, Alaa
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik. Palestine Polytechnic University.
    Feng, Shengzhong
    Chinese Academy of Science, China.
    Li, Haibo
    Royal Institute of Technology, Stockholm, Sweden.
    Ur Réhman, Shafiq
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Multimodal Hand and Foot Gesture Interaction for Handheld Devices2014Ingår i: ACM Transactions on Multimedia Computing, Communications, and Applications (TOMCCAP), ISSN 1551-6857, E-ISSN 1551-6865, Vol. 11, nr 1, artikel-id 10Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We present a hand-and-foot-based multimodal interaction approach for handheld devices. Our method combines input modalities (i.e., hand and foot) and provides a coordinated output to both modalities along with audio and video. Human foot gesture is detected and tracked using contour-based template detection (CTD) and Tracking-Learning-Detection (TLD) algorithm. 3D foot pose is estimated from passive homography matrix of the camera. 3D stereoscopic and vibrotactile are used to enhance the immersive feeling. We developed a multimodal football game based on the multimodal approach as a proof-of-concept. We confirm our systems user satisfaction through a user study.

  • 94.
    Lundström, Benjamin
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    IT-säkerhet: Största IT-säkerhetshoten mot svenska företag och organisationer idag, samt kontemporära bekämpningsmetoder och verktyg mot dessa IT-säkerhetshot.2016Självständigt arbete på grundnivå (högskoleexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Olika former av IT-relaterade hot har förekommit sedan internets födelse. Inledningsvis var de harmlösa humoristiska program som över tiden utvecklades till kriminella verktyg med ekonomiska syften. Elakartad programkod benämns under samlingsnamnet Malware. En angripare besitter idag ett stort antal metoder för otillåten tillgång till system, neka legitima användare tillgång till system eller på ett stort antal sätt bedriva kriminell verksamhet av ekonomisk karaktär.

    Skydds- och bekämpningsmetoderna innefattar brandväggar, olika analys-, detektions- och preventionssystem (IDS/IPS) och kryptering. Men för att komma tillrätta med IT-hoten fullt ut krävs också säkerhetsutbildning och incidenthantering som sker via incidentplanering, rapporter, dokumentation, backup och informationsklassning.

    Kontemporära IT-säkerhetshot av betydande art belyses i rapporten. Stuxnet (2009), som angrep Irans kärnvapenforskning. Flamer (2011), ett cybervapen vars syfte är spårlös informationsinhämtning. BlackEnergy (2015) och angreppet mot elförsörjningen i Ukraina. DDoS-attacken mot Svenska medier behandlas liksom Petya (2016) som är nya generationens Ransomeware.

    Det är vitalt för företag och organisationer att skydda sin viktigaste tillgång, informationen. Både mot cyberkriminella element i rent finansiellt syfte men i tilltagande grad också mot olika cybervapen och möjligtvis också mot cyberterrorism.

  • 95.
    Maggio, Martina
    et al.
    Lund University.
    Klein, Cristian
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Årzén, Karl-Erik
    Lund University.
    Control strategies for predictable brownouts in cloud applications2014Ingår i: IFAC PAPERSONLINE, 2014, Vol. 47, s. 689-694Konferensbidrag (Refereegranskat)
    Abstract [en]

    Cloud computing is an application hosting model providing the illusion of infinite computing power. However, even the largest datacenters have finite computing capacity, thus cloud infrastructures have experienced overload due to overbooking or transient failures. The topic of this paper is the comparison of different control strategies to mitigate overload for datacenters, that assume that the running cloud applications are cooperative and help the infrastructure in recovering from critical events. Specifically, the paper investigates the behavior of different controllers when they have to keep the average response time of a cloud application below a certain threshold by acting on the probability of serving requests with optional computations disabled, where the pressure exerted by each request on the infrastructure is diminished, at the expense of user experience.

  • 96.
    Mariela, Morveli-Espinoza
    et al.
    Federal University of Technology - Paraná (UTFPR), Curitiba, Brazil.
    Nieves, Juan Carlos
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Ayslan, Trevizan
    Federal University of Technology - Paraná (UTFPR), Curitiba, Brazil.
    J., Puyol-Gruart
    Artificial Intelligence Research Institute (IIIA-CSIC), Barcelona, Spain.
    Cesar, Tacla
    Federal University of Technology - Paraná (UTFPR), Curitiba, Brazil.
    An Argumentation-based Approach for Identifying and Dealing with Incompatibilities among Procedural Goals2019Ingår i: International Journal of Approximate Reasoning, ISSN 0888-613X, E-ISSN 1873-4731, Vol. 105, s. 1-26Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    During the first step of practical reasoning, i.e. deliberation, an intelligent agent generates a set of pursuable goals and then selects which of them he commits to achieve. An intelligent agent may in general generate multiple pursuable goals, which may be incompatible among them. In this paper, we focus on the definition, identification and resolution of these incompatibilities. The suggested approach considers the three forms of incompatibility introduced by Castelfranchi and Paglieri, namely the terminal incompatibility, the instrumental or resources incompatibility and the superfluity. We characterize computationally these forms of incompatibility by means of arguments that represent the plans that allow an agent to achieve his goals. Thus, the incompatibility among goals is defined based on the conflicts among their plans, which are represented by means of attacks in an argumentation framework. We also work on the problem of goals selection; we propose to use abstract argumentation theory to deal with this problem, i.e. by applying argumentation semantics. We use a modified version of the “cleaner world” scenario in order to illustrate the performance of our proposal.

  • 97.
    Mehta, Amardeep
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Resource allocation for Mobile Edge Clouds2018Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Recent advances in Internet technologies have led to the proliferation of new distributed applications in the transportation, healthcare, mining, security, and entertainment sectors. The emerging applications have characteristics such as being bandwidth-hungry, latency-critical, and applications with a user population contained within a limited geographical area, and require high availability, low jitter, and security.

    One way of addressing the challenges arising because of these emerging applications, is to move the computing capabilities closer to the end-users, at the logical edge of a network, in order to improve the performance, operating cost, and reliability of applications and services. These distributed new resources and software stacks, situated on the path between today's centralized data centers and devices in close proximity to the last mile network, are known as Mobile Edge Clouds (MECs). The distributed MECs provides new opportunities for the management of compute resources and the allocation of applications to those resources in order to minimize the overall cost of application deployment while satisfying end-user demands in terms of application performance.

    However, these opportunities also present three significant challenges. The first challenge is where and how much computing resources to deploy along the path between today's centralized data centers and devices for cost-optimal operations. The second challenge is where and how much resources should be allocated to which applications to meet the applications' performance requirements while minimizing operational costs. The third challenge is how to provide a framework for application deployment on resource-constrained IoT devices in heterogeneous environments. 

    This thesis addresses the above challenges by proposing several models, algorithms, and simulation and software frameworks. In the first part, we investigate methods for early detection of short-lived and significant increase in demand for computing resources (also called spikes) which may cause significant degradation in the performance of a distributed application. We make use of adaptive signal processing techniques for early detection of spikes. We then consider trade-offs between parameters such as the time taken to detect a spike and the number of false spikes that are detected. In the second part, we study the resource planning problem where we study the cost benefits of adding new compute resources based on performance requirements for emerging applications. In the third part, we study the problem of allocating resources to applications by formulating as an optimization problem, where the objective is to minimize overall operational cost while meeting the performance targets of applications. We also propose a hierarchical scheduling framework and policies for allocating resources to applications based on performance metrics of both applications and compute resources. In the last part, we propose a framework, Calvin Constrained, for resource-constrained devices, which is an extension of the Calvin framework and supports a limited but essential subset of the features of the reference framework taking into account the limited memory and processing power of the resource-constrained IoT devices.

  • 98.
    Mehta, Amardeep
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Bayuh Lakew, Ewnetu
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Tordsson, Johan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Elmroth, Erik
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Utility-based Allocation of Industrial IoT Applications in Mobile Edge Clouds2018Rapport (Övrigt vetenskapligt)
    Abstract [en]

    Mobile Edge Clouds (MECs) create new opportunities and challenges in terms of scheduling and running applications that have a wide range of latency requirements, such as intelligent transportation systems, process automation, and smart grids. We propose a two-tier scheduler for allocating runtime resources to Industrial Internet of Things (IIoTs) applications in MECs. The scheduler at the higher level runs periodically – monitors system state and the performance of applications – and decides whether to admit new applications and migrate existing applications. In contrast, the lower-level scheduler decides which application will get the runtime resource next. We use performance based metrics that tells the extent to which the runtimes are meeting the Service Level Objectives (SLOs) of the hosted applications. The Application Happiness metric is based on a single application’s performance and SLOs. The Runtime Happiness metric is based on the Application Happiness of the applications the runtime is hosting. These metrics may be used for decision-making by the scheduler, rather than runtime utilization, for example.

    We evaluate four scheduling policies for the high-level scheduler and five for the low-level scheduler. The objective for the schedulers is to minimize cost while meeting the SLO of each application. The policies are evaluated with respect to the number of runtimes, the impact on the performance of applications and utilization of the runtimes. The results of our evaluation show that the high-level policy based on Runtime Happiness combined with the low-level policy based on Application Happiness outperforms other policies for the schedulers, including the bin packing and random strategies. In particular, our combined policy requires up to 30% fewer runtimes than the simple bin packing strategy and increases the runtime utilization up to 40% for the Edge Data Center (DC) in the scenarios we evaluated.

  • 99.
    Mehta, Amardeep
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Bayuh Lakew, Ewnetu
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Tordsson, Johan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Elmroth, Erik
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Utility-based Allocation of Industrial IoT Applications in Mobile Edge Clouds2018Ingår i: 2018 IEEE 37th International Performance Computing and Communications Conference (IPCCC), IEEE, 2018Konferensbidrag (Refereegranskat)
    Abstract [en]

    Mobile Edge Clouds (MECs) create new opportunities and challenges in terms of scheduling and running applications that have a wide range of latency requirements, such as intelligent transportation systems, process automation, and smart grids. We propose a two-tier scheduler for allocating runtime resources to Industrial Internet of Things (IIoT) applications in MECs. The scheduler at the higher level runs periodically - monitors system state and the performance of applications - and decides whether to admit new applications and migrate existing applications. In contrast, the lower-level scheduler decides which application will get the runtime resource next. We use performance based metrics that tells the extent to which the runtimes are meeting the Service Level Objectives (SLOs) of the hosted applications. The Application Happiness metric is based on a single application's performance and SLOs. The Runtime Happiness metric is based on the Application Happiness of the applications the runtime is hosting. These metrics may be used for decision-making by the scheduler, rather than runtime utilization, for example. We evaluate four scheduling policies for the high-level scheduler and five for the low-level scheduler. The objective for the schedulers is to minimize cost while meeting the SLO of each application. The policies are evaluated with respect to the number of runtimes, the impact on the performance of applications and utilization of the runtimes. The results of our evaluation show that the high-level policy based on Runtime Happiness combined with the low-level policy based on Application Happiness outperforms other policies for the schedulers, including the bin packing and random strategies. In particular, our combined policy requires up to 30% fewer runtimes than the simple bin packing strategy and increases the runtime utilization up to 40% for the Edge Data Center (DC) in the scenarios we evaluated.

  • 100.
    Mehta, Amardeep
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Elmroth, Erik
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Distributed Cost-Optimized Placement for Latency-Critical Applications in Heterogeneous Environments2018Ingår i: Proceedings of the IEEE 15th International Conference on Autonomic Computing (ICAC), IEEE Computer Society, 2018, s. 121-130Konferensbidrag (Refereegranskat)
    Abstract [en]

    Mobile Edge Clouds (MECs) with 5G will create new opportunities to develop latency-critical applications in domains such as intelligent transportation systems, process automation, and smart grids. However, it is not clear how one can costefficiently deploy and manage a large number of such applications given the heterogeneity of devices, application performance requirements, and workloads. This work explores cost and performance dynamics for IoT applications, and proposes distributed algorithms for automatic deployment of IoT applications in heterogeneous environments. Placement algorithms were evaluated with respect to metrics including number of required runtimes, applications’ slowdown, and the number of iterations used to place an application. Iterative search-based distributed algorithms such as Size Interval Actor Assignment in Groups (SIAA G) outperformed random and bin packing algorithms, and are therefore recommended for this purpose. Size Interval Actor Assignment in Groups at Least Utilized Runtime (SIAA G LUR) algorithm is also recommended when minimizing the number of iterations is important. The tradeoff of using SIAA G algorithms is a few extra runtimes compared to bin packing algorithms.

1234 51 - 100 av 168
RefereraExporteraLänk till träfflistan
Permanent länk
Referera
Referensformat
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annat format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annat språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf