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  • 1.
    Abdulla, PA
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Mathematics and Computer Science, Department of Information Technology. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Mathematics and Computer Science, Department of Information Technology, Computer Systems. DEPARTMENT OF COMPUTER SYSTEMS.
    Boasson, L
    Bouajjani, A
    Effective Lossy Queue Languages.2001In: ICALP'2001, 28th Int. Colloquium on Automata, Languages and Programmming., 2001Conference paper (Refereed)
  • 2.
    Abdulla, PA
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Mathematics and Computer Science, Department of Information Technology. DEPARTMENT OF COMPUTER SYSTEMS.
    Jonsson, B
    Channel Abstractions in Protocol Verification2001In: CONCUR'2001, 12th Int. Conf. on Concurrency Theory, 2001Conference paper (Refereed)
  • 3.
    Abdulla, Parosh A.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Delzanno, Giorgio
    Univ Genoa, DIBRIS, Genoa, Italy..
    Parameterized verification2016In: International Journal on Software Tools for Technology Transfer (STTT), ISSN 1433-2779, E-ISSN 1433-2787, Vol. 18, no 5, 469-473 p.Article in journal (Other academic)
    Abstract [en]

    The goal of parameterized verification is to prove the correctness of a system specification regardless of the number of its components. The problem is of interest in several different areas: verification of hardware design, multithreaded programs, distributed systems, and communication protocols. The problem is undecidable in general. Solutions for restricted classes of systems and properties have been studied in areas like theorem proving, model checking, automata and logic, process algebra, and constraint solving. In this introduction to the special issue, dedicated to a selection of works from the Parameterized Verification workshop PV '14 and PV '15, we survey some of the works developed in this research area.

  • 4.
    Abdulla, Parosh A.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Delzanno, Giorgio
    Univ Genoa, Genoa, Italy..
    Montali, Marco
    Free Univ Bolzano, Bolzano, Italy..
    Well Structured Transition Systems with History2015In: Electronic Proceedings in Theoretical Computer Science, ISSN 2075-2180, E-ISSN 2075-2180, no 193, 115-128 p.Article in journal (Refereed)
    Abstract [en]

    We propose a formal model of concurrent systems in which the history of a computation is explicitly represented as a collection of events that provide a view of a sequence of configurations. In our model events generated by transitions become part of the system configurations leading to operational semantics with historical data. This model allows us to formalize what is usually done in symbolic verification algorithms. Indeed, search algorithms often use meta-information, e.g., names of fired transitions, selected processes, etc., to reconstruct (error) traces from symbolic state exploration. The other interesting point of the proposed model is related to a possible new application of the theory of well-structured transition systems (wsts). In our setting wsts theory can be applied to formally extend the class of properties that can be verified using coverability to take into consideration (ordered and unordered) historical data. This can be done by using different types of representation of collections of events and by combining them with wsts by using closure properties of well-quasi orderings.

  • 5. Abdulla, Parosh Aziz
    Carrying Probabilities to the Infinite World2011In: CONCUR'2011, 22nd International Conference on Concurrency Theory., 2011Conference paper (Refereed)
  • 6.
    Abdulla, Parosh Aziz
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Mathematics and Computer Science, Department of Information Technology. DEPARTMENT OF COMPUTER SYSTEMS.
    Using (Timed) Petri Nets for Verification of Parametrized (Timed) Systems2001In: VEPAS'2001, Verification of Parameterized Systems, 2001Conference paper (Refereed)
  • 7.
    Abdulla, Parosh Aziz
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Atig, Mohamed Faouzi
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Kaxiras, Stefanos
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Architecture and Computer Communication.
    Leonardsson, Carl
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Ros, Alberto
    Zhu, Yunyun
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Fencing programs with self-invalidation and self-downgrade2016In: Formal Techniques for Distributed Objects, Components, and Systems, Springer, 2016, 19-35 p.Conference paper (Refereed)
  • 8.
    Abdulla, Parosh Aziz
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Chen, Yu-Fang
    Clemente, Lorenzo
    Holík, Lukás
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Hong, Chih-Duo
    Mayr, Richard
    Vojnar, Tomás
    Advanced Ramsey-based Büchi automata inclusion testing2011In: CONCUR 2011 — Concurrency Theory, Springer Berlin/Heidelberg, 2011, 187-202 p.Conference paper (Refereed)
  • 9.
    Abdulla, Parosh Aziz
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Delzanno, Giorgio
    Univ Genoa, I-16126 Genoa, Italy..
    Rezine, Othmane
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems. Uppsala Univ, Uppsala, Sweden..
    Sangnier, Arnaud
    Univ Paris Diderot, CNRS, LIAFA, Paris, France..
    Traverso, Riccardo
    FBK, Trento, Italy..
    Parameterized verification of time-sensitive models of ad hoc network protocols2016In: Theoretical Computer Science, ISSN 0304-3975, E-ISSN 1879-2294, Vol. 612, 1-22 p.Article in journal (Refereed)
    Abstract [en]

    We study decidability and undecidability results for parameterized verification of a formal model of timed Ad Hoc network protocols. The communication topology is defined by an undirected graph and the behaviour of each node is defined by a timed automaton communicating with its neighbours via broadcast messages. We consider parameterized verification problems formulated in terms of reachability. In particular we are interested in searching for an initial configuration from which an individual node can reach an error state. We study the problem for dense and discrete time and compare the results with those obtained for (fully connected) networks of timed automata.

  • 10.
    Abdulla, Parosh Aziz
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology.
    Delzanno, Giorgio
    Van Begin, Laurent
    A classification of the expressive power of well-structured transition systems2011In: Information and Computation, ISSN 0890-5401, E-ISSN 1090-2651, Vol. 209, no 3, 248-279 p.Article in journal (Refereed)
    Abstract [en]

    We compare the expressive power of a class of well-structured transition systems that includes relational automata (extensions of), Petri nets, lossy channel systems, constrained multiset rewriting systems, and data nets. For each one of these models we study the class of languages generated by labeled transition systems describing their semantics. We consider here two types of accepting conditions: coverability and reachability of a fixed a priori configuration. In both cases we obtain a strict hierarchy in which constrained multiset rewriting systems is the most expressive model.

  • 11.
    Abdulla, Parosh Aziz
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Mathematics and Computer Science, Department of Information Technology. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Mathematics and Computer Science, Department of Information Technology, Computer Systems. Datorteknik.
    Jonsson, Bengt
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Mathematics and Computer Science, Department of Information Technology. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Mathematics and Computer Science, Department of Information Technology, Computer Systems. Datorteknik.
    Model checking of systems with many identical timed processes2003In: Theoretical Computer Science, ISSN 0304-3975, Vol. 290, no 1, 241-264 p.Article in journal (Refereed)
  • 12. Abdulla, Parosh Aziz
    et al.
    Leino, Rustan
    TACAS'2011, 17th International ConferenceTools and Algorithms for the Construction and Analysis of Systems.2011Conference proceedings (editor) (Refereed)
  • 13.
    Abdulla, Parosh Aziz
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Richard, Mayr
    Computing Optimal Coverability Costs in Priced Timed Petri Nets2011In: LICS'2011, Proceedings of the 26th Annual IEEE Symposium on Logic in Computer Science, 2011, 399-408 p.Conference paper (Refereed)
    Abstract [en]

    We consider timed Petri nets, i.e., unbounded Petri nets where each token carries a real-valued clock. Transition arcs are labeled with time intervals, which specify constraints on the ages of tokens. Our cost model assigns token storage costs per time unit to places, and firing costs to transitions. We study the cost to reach a given control-state. In general, a cost-optimal run may not exist. However, we show that the infimum of the costs is computable.

  • 14.
    Abdulla, Parosh
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Mathematics and Computer Science, Department of Information Technology. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Mathematics and Computer Science, Department of Information Technology, Computer Systems. DoCS.
    Ben Henda, Noomene
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Mathematics and Computer Science, Department of Information Technology. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Mathematics and Computer Science, Department of Information Technology, Computer Systems. DoCS.
    Mayr, Richard
    Sandberg, Sven
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Mathematics and Computer Science, Department of Information Technology. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Mathematics and Computer Science, Department of Information Technology, Computer Systems. Datalogi.
    Limiting Behavior of Markov Chains with Eager Attractors2006In: Third International Conference on the Quantitative Evaluation of Systems (QEST), 2006, 253-262 p.Conference paper (Refereed)
  • 15.
    Ahlgren, Bengt
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Computer Systems. Swedish Institute of Computer Science.
    Improving Computer Communication Performance by Reducing Memory Bandwidth Consumption1997Doctoral thesis, comprehensive summary (Other academic)
  • 16.
    Alirezaie, Marjan
    et al.
    Örebro University.
    Renoux, Jennifer
    Örebro University.
    Köckemann, Uwe
    Örebro University.
    Kristoffersson, Annica
    Örebro University.
    Karlsson, Lars
    Örebro University.
    Blomqvist, Eva
    SICS East.
    Tsiftes, Nicolas
    SICS.
    Voigt, Thiemo
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Architecture and Computer Communication. SICS.
    Loutfi, Amy
    Örebro University.
    An Ontology-based Context-aware System for Smart Homes: E-care@ home2017In: Sensors, ISSN 1424-8220, E-ISSN 1424-8220, Vol. 17, no 7Article in journal (Refereed)
  • 17. Alonso, Juan M.
    et al.
    Nordhamn, Amanda
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Architecture and Computer Communication.
    Olofsson, Simon
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Architecture and Computer Communication.
    Voigt, Thiemo
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Architecture and Computer Communication.
    Bounds on the lifetime of wireless sensor networks with lossy links and directional antennas2016In: Wireless Network Performance Enhancement via Directional Antennas: Models, Protocols, and Systems, Boca Raton, FL: CRC Press, 2016, 329-361 p.Chapter in book (Refereed)
  • 18.
    Amnell, Tobias
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Computer Systems. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Code synthesis for timed automata2003Licentiate thesis, monograph (Other scientific)
    Abstract [en]

    In this thesis, we study executable behaviours of timed models. The focus is on synthesis of executable code with predictable behaviours from high level abstract models. We assume that a timed system consists of two parts: the control software and the plant (i.e. the environment to be controlled). Both are modelled as timed automata extended with real time tasks. We consider the extended timed automata as design models.

    We present a compilation procedure to transform design models to executable code including a run-time scheduler (run time system) preserving the correctness and schedulability of the models. The compilation procedure has been implemented in a prototype C-code generator for the brickOS operating system included in the Times tool. We also present an animator, based on hybrid automata, to be used to describe a simulated environment (i.e. the plant) for timed systems. The tasks of the hybrid automata define differential equations and the animator uses a differential equations solver to calculate step-wise approximations of real valued variables. The animated objects, described as hybrid automata, are compiled by the Times tool into executable code using a similar procedure as for controller software.

    To demonstrate the applicability of timed automata with tasks as a design language we have developed the control software for a production cell. The production cell is built in LEGO and is controlled by a Hitachi H8 based LEGO-Mindstorms control brick. The control software has been analysed (using the Times tool) for schedulability and other safety properties. Using results from the analysis we were able to avoid generating code for parts of the design that could never be reached, and could also limit the amount of memory allocated for the task queue.

  • 19.
    Atig, Mohamed Faouzi
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Bouajjani, Ahmed
    Burckhardt, Sebastian
    Musuvathi, Madanlal
    What's decidable about weak memory models?2012In: Programming Languages and Systems, Springer Berlin/Heidelberg, 2012, 26-46 p.Conference paper (Refereed)
    Abstract [en]

    We investigate the decidability of the state reachability problem in finite-state programs running under weak memory models. In [3], we have shown that this problem is decidable for TSO and its extension with the write-to-write order relaxation, but beyond these models nothing is known to be decidable. Moreover, we have shown that relaxing the program order by allowing reads or writes to overtake reads leads to undecidability. In this paper, we refine these results by sharpening the (un)decidability frontiers on both sides. On the positive side, we introduce a new memory model NSW (for non-speculative writes) that extends TSO with the write-to-write relaxation, the read-to-read relaxation, and support for partial fences. We present a backtrack-free operational model for NSW, and prove that it does not allow causal cycles (thus barring pathological out-of-thin-air effects). On the negative side, we show that adding the read-to-write relaxation to TSO causes undecidability, and that adding non-atomic writes to NSW also causes undecidability. Our results establish that NSW is the first known hardware-centric memory model that is relaxed enough to permit both delayed execution of writes and early execution of reads for which the reachability problem is decidable.

  • 20.
    Bagci, Ibrahim Ethem
    et al.
    Univ Lancaster, Sch Comp & Commun, Lancaster, England.
    Raza, Shahid
    SICS Swedish ICT, Kista, Sweden.
    Roedig, Utz
    Univ Lancaster, Sch Comp & Commun, Lancaster, England.
    Voigt, Thiemo
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Architecture and Computer Communication. SICS Swedish ICT, Kista, Sweden.
    Fusion: Coalesced Confidential Storage and Communication Framework for the IoT2016In: Security and Communication Networks, ISSN 1939-0114, E-ISSN 1939-0122, Vol. 9, no 15, 2656-2673 p.Article in journal (Refereed)
    Abstract [en]

    Comprehensive security mechanisms are required for a successful implementation of the Internet of Things (IoT). Existing solutions focus mainly on securing the communication links between Internet hosts and IoT devices. However, as most IoT devices nowadays provide vast amounts of flash storage space, it is as well required to consider storage security within a comprehensive security framework. Instead of developing independent security solutions for storage and communication, we propose Fusion, a framework that provides coalesced confidential storage and communication. Fusion uses existing secure communication protocols for the IoT such as Internet protocol security (IPsec) and datagram transport layer security (DTLS) and re-uses the defined communication security mechanisms within the storage component. Thus, trusted mechanisms developed for communication security are extended into the storage space. Notably, this mechanism allows us to transmit requested data directly from the file system without decrypting read data blocks and then re-encrypting these for transmission. Thus, Fusion provides benefits in terms of processing speed and energy efficiency, which are important aspects for resource-constrained IoT devices. This paper describes the Fusion architecture and its instantiation for IPsec-based and DTLS-based systems. We describe Fusion's implementation and evaluate its storage overheads, communication performance, and energy consumption.

  • 21.
    Behboodi, Arash
    et al.
    TU Berlin.
    Wirström, Niklas
    SICS.
    Lemic, Filip
    TU Berlin.
    Voigt, Thiemo
    SICS.
    Wolisz, Adam
    TU Berlin.
    Interference Effect on Localization Solutions: Signal Feature Perspective2015Conference paper (Refereed)
  • 22.
    Bengtsson, Johan
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Computer Systems. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Efficient symbolic state exploration of timed systems: Theory and implementation2001Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Timing aspects are important for the correctness of safety-critical systems. It is crucial that these aspects are carefully analysed in designing such systems. UPPAAL is a tool designed to automate the analysis process. In UPPAAL, a system under construction is described as a network of timed automata and the desired properties of the system can be specified using a query language. Then UPPAAL can be used to explore the state space of the system description to search for states violating (or satisfying) the properties. If such states are found, the tool provides diagnostic information, in form of executions leading to the states, to help the desginers, for example, to locate bugs in the design.

    The major problem for UPPAAL and other tools for timed systems to deal with industrial-size applications is the state space explosion. This thesis studies the sources of the problem and develops techniques for real-time model checkers, such as UPPAAL, to attack the problem. As contributions, we have developed the notion of committed locations to model atomicity and local-time semantics for timed systems to allow partial order reductions, and a number of implementation techniques to reduce time and space consumption in state space exploration. The techniques are studied and compared by case studies. Our experiments demonstrate significant improvements on the performance of UPPAAL.

  • 23.
    Berg, Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Computer Systems. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Methods for run time analysis of data locality2003Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    The growing gap between processor clock speed and DRAM access time puts new demands on software and development tools. Deep memory hierarchies and high cache miss penalties in present and emerging computer systems make execution time sensitive to data locality. Therefore, developers of performance-critical applications and optimizing compilers must be aware of data locality and maximize cache utilization to produce fast code. To aid the optimization process and help understanding data locality, we need methods to analyze programs and pinpoint poor cache utilization and possible optimization opportunities.

    Current methods for run-time analysis of data locality and cache behavior include functional cache simulation, often combined with set sampling or time sampling, other regularity metrics based on strides and data streams, and hardware monitoring. However, they all share the trade-off between run-time overhead, accuracy and explanatory power.

    This thesis presents methods to efficiently analyze data locality at run time based on cache modeling. It suggests source-interdependence profiling as a technique for examining the cache behavior of applications and locating source code statements and/or data structures that cause poor cache utilization. The thesis also introduces a novel statistical cache-modeling technique, StatCache. Rather than implementing a functional cache simulator, StatCache estimates the miss ratios of fully-associative caches using probability theory. A major advantage of the method is that the miss ratio estimates can be based on very sparse sampling. Further, a single run of an application is enough to estimate the miss ratio of caches of arbitrary sizes and line sizes and to study both spatial and temporal data locality.

  • 24.
    Berg, Therese
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Mathematics and Computer Science, Department of Information Technology. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Mathematics and Computer Science, Department of Information Technology, Computer Systems. datorteknik.
    Jonsson, Bengt
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Mathematics and Computer Science, Department of Information Technology. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Mathematics and Computer Science, Department of Information Technology, Computer Systems. datorteknik.
    Raffelt, Harald
    Regular Inference for State Machines with Parameters.2006In: Fundamental Approaches to Software Engineering, 9th International Conference, FASE 2006,, 2006, 107-121 p.Conference paper (Refereed)
    Abstract [en]

    We present experiences from a case study where a model-based approach to black-box testing is applied to verify that a Wireless Application Protocol (WAP) gateway conforms to its specification.The WAP gateway is developed by Ericsson and used in mobile telephone networks to connect mobile phones with the Internet. We focus on testing the software implementing the session (WSP) and transaction (WTP) layers of the WAP protocol. These layers, and their surrounding environment, are described as a network of timed automata. To model the many sequence numbers (from a large domain) used in the protocol, we introduce an abstraction technique. We believe the suggested abstraction

    technique will prove useful to model and analyse other similar protocols with sequence numbers, in particular in the context of model-based testing.

    A complete test bed is presented, which includes generation and execution of test cases. It takes as input a model and a coverage criterion expressed as an observer, and returns a verdict for each test case. The test bed includes existing

    tools from Ericsson for test-case execution. To generate test suites, we use our own tool CoVer --- a new test-case generation tool based on the real-time model-checker Uppaal.

  • 25.
    Berg, Therese
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Mathematics and Computer Science, Department of Information Technology. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Mathematics and Computer Science, Department of Information Technology. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Mathematics and Computer Science, Department of Information Technology, Computer Systems. Department of Computer Systems.
    Raffelt, Harald
    Model-based Testing of Reactive Systems: 19 Model Checking2005Chapter in book (Refereed)
  • 26.
    Berglund, Anders
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Mathematics and Computer Science, Department of Information Technology. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    A Framework to study learning in an internationally distributed course.2003In: Communities of Practise.: Research Proceedings of the 10th Association for Learning Technology Conference (ALT-C 2003), 2003, 27-39 p.Conference paper (Refereed)
  • 27.
    Berglund, Anders
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Mathematics and Computer Science, Department of Information Technology. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Learning computer systems in a distributed course: Problematizing content and context.2002In: Proceedings of the European Association for Research on Learning and Instruction, SIG 10, Current Issues in Phenomenography, 2002Conference paper (Refereed)
    Abstract [en]

    In this paper, a research study of learning computer systems in a complex, internationally distributed course environment is described. The relation between a learner and the object of his/her studies being in focus in phenomenographic research is enhance

  • 28.
    Berglund, Anders
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Mathematics and Computer Science, Department of Information Technology. Datorteknik. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    What is good teaching of computer networks?.2003In: Proceedings of 33rd Annual Frontiers in Education, 2003, 2SD13-2SD19 p.Conference paper (Refereed)
  • 29.
    Berglund, Anders
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Mathematics and Computer Science, Department of Information Technology. Datorteknik. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Booth, Shirley
    Are you guys really concerned about the grades?2002In: Proceedings of ISCRAT2002, 2002Conference paper (Refereed)
  • 30.
    Berglund, Anders
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Mathematics and Computer Science, Department of Information Technology. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Pears, Arnold
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Mathematics and Computer Science, Department of Information Technology. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Students' Understanding of Networks in an Internationally Distributed Course.2003In: Proceedings of 3rd IEEE International Conference of Advanced Learning Technologies (ICALT 2003)., 2003, 380-381 p.Conference paper (Refereed)
  • 31.
    Bergquist, Jonatan
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Computing Science.
    Blockchain Technology and Smart Contracts: Privacy-preserving Tools2017Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The purpose of this Master's thesis is to explore blockchain technology and smart contracts as a way of building privacy-sensitive applications. The main focus is on a medication plan containing prescriptions, built on a blockchain system of smart contracts. This is an example use case, but the results can be transferred to other ones where sensitive data is being shared and a proof of validity or authentication is needed. First the problem is presented, why medication plans are in need of digitalisation and why blockchain technology is a fitting technology for implementing such an application. Then blockchain technology is explained, since it is a very new and relatively unfamiliar IT construct. Thereafter, a design is proposed for solving the problem. A system of smart contracts was built to prove how such an application can be built, and suggested guidelines for how a blockchain system should be designed to fulfil the requirements that were defined. Finally, a discussion is held regarding the applicability of different blockchain designs to the problem of privacy-handling applications.

  • 32. Bernáld, Helena
    et al.
    Cajander, Åsa
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computerized Image Analysis and Human-Computer Interaction.
    Daniels, Mats
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Kultur, Can
    Löfström, Anette
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computerized Image Analysis and Human-Computer Interaction.
    McDermott, Roger
    Russell Dag, Lori
    Intercultural competence in global collaboration courses in computer engineering2012In: Advances in Design for Cross-Cultural Activities: Part I, Boca Raton, FL: CRC Press, 2012, 351-361 p.Conference paper (Refereed)
  • 33.
    Björnfot, Lars
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Computer Systems.
    Specification and Implementation of Distributed Real-Time Systems for Embedded Applications1996Doctoral thesis, comprehensive summary (Other academic)
  • 34.
    Bohlin, Therese
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Computer Systems. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Regular Inference for Communication Protocol Entities2009Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    A way to create well-functioning computer systems is to automate error detection in the systems. Automated techniques for finding errors, such as testing and formal verification, requires a model of the system. The technique for constructing deterministic finite automata (DFA) models, without access to the source code, is called regular inference. The technique provides sequences of input, so called membership queries, to a system, observes the responses, and infers a model from the input and responses.

    This thesis presents work to adapt regular inference to a certain kind of systems: communication protocol entities. Such entities interact by sending and receiving messages consisting of a message type and a number of parameters, each of which potentially can take on a large number of values. This may cause a model of a communication protocol entity inferred by regular inference, to be very large and take a long time to infer. Since regular inference creates a model from the observed behavior of a communication protocol entity, the model may be very different from a designer's model of the system's source code.

    This thesis presents adaptations of regular inference to infer more compact models and use less membership queries. The first contribution is a survey over three algorithms for regular inference. We present their similarities and their differences in terms of the required number of membership queries. The second contribution is an investigation on how many membership queries a common regular inference algorithm, the L* algorithm by Angluin, requires for randomly generated DFAs and randomly generated DFAs with a structure common for communication protocol entities. In comparison, the DFAs with a structure common for communication protocol entities require more membership queries. The third contribution is an adaptation of regular inference to communication protocol entities which behavior foremost are affected by the message types. The adapted algorithm avoids asking membership queries containing messages with parameter values that results in already observed responses. The fourth contribution is an approach for regular inference of communication protocol entities which communicate with messages containing parameter values from very large ranges. The approach infers compact models, and uses parameter values taken from a small portion of their ranges in membership queries. The fifth contribution is an approach to infer compact models of communication protocol entities which have a similar partitioning of an entity's behavior into control states as in a designer's model of the protocol.

    List of papers
    1. Model Checking
    Open this publication in new window or tab >>Model Checking
    2005 (English)In: Model-Based Testing of Reactive Systems: Advanced Lectures, Berlin / Heidelberg: Springer , 2005, 557-603 p.Chapter in book (Other academic)
    Place, publisher, year, edition, pages
    Berlin / Heidelberg: Springer, 2005
    Series
    Lecture Notes in Computer Sciences: Programming and Software Engineering, ISSN 0302-9743 ; 3472
    National Category
    Computer and Information Science
    Identifiers
    urn:nbn:se:uu:diva-98082 (URN)978-3-540-26278-7 (ISBN)
    Available from: 2009-02-06 Created: 2009-02-06 Last updated: 2009-09-29Bibliographically approved
    2. Insights to Angluin's Learning
    Open this publication in new window or tab >>Insights to Angluin's Learning
    2005 (English)In: Electronical Notes in Theoretical Computer Science, ISSN 1571-0661, Vol. 118, 3-18 p.Article in journal (Refereed) Published
    Abstract [en]

    Among other domains, learning finite-state machines is important for obtaining a model of a system under development, so that powerful formal methods such as model checking can be applied.

    A prominent algorithm for learning such devices was developed by Angluin. We have implemented this algorithm in a straightforward way to gain further insights to practical applicability. Furthermore, we have analyzed its performance on randomly generated as well as real-world examples. Our experiments focus on the impact of the alphabet size and the number of states on the needed number of membership queries. Additionally, we have implemented and analyzed an optimized version for learning prefix-closed regular languages. Memory consumption is one major obstacle when we attempted to learn large examples.

    We see that prefix-closed languages are relatively hard to learn compared to arbitrary regular languages. The optimization, however, shows positive results.

    Keyword
    deterministic finite-state automata, learning algorithm, regular languages, prefix-closed regular languages
    National Category
    Computer and Information Science
    Identifiers
    urn:nbn:se:uu:diva-98083 (URN)10.1016/j.entcs.2004.12.015 (DOI)
    Available from: 2009-02-06 Created: 2009-02-06 Last updated: 2009-09-29Bibliographically approved
    3. Regular Inference for State Machines with Parameters
    Open this publication in new window or tab >>Regular Inference for State Machines with Parameters
    2006 (English)In: Fundamental approaches to software engineering: ( 9th international conference, FASE 2006, held as part of the Joint European Conferences on Theory and Practice of Software, ETAPS 2006, Vienna, Austria, March 27-28, 2006 ), Berlin: Springer , 2006, 107-121 p.Chapter in book (Other academic)
    Abstract [en]

    Techniques for inferring a regular language, in the form of a finite automaton, from a sufficiently large sample of accepted and nonaccepted input words, have been employed to construct models of software and hardware systems, for use, e.g., in test case generation. We intend to adapt these techniques to construct state machine models of entities of communication protocols. The alphabet of such state machines can be very large, since a symbol typically consists of a protocol data unit type with a number of parameters, each of which can assume many values. In typical algorithms for regular inference, the number of needed input words grows with the size of the alphabet and the size of the minimal DFA accepting the language. We therefore modify such an algorithm (Angluin's algorithm) so that its complexity grows not with the size of the alphabet, but only with the size of a certain symbolic representation of the DFA. The main new idea is to infer, for each state, a partitioning of input symbols into equivalence classes, under the hypothesis that all input symbols in an equivalence class have the same effect on the state machine. Whenever such a hypothesis is disproved, equivalence classes are refined. We show that our modification retains the good properties of Angluin's original algorithm, but that its complexity grows with the size of our symbolic DFA representation rather than with the size of the alphabet. We have implemented the algorithm; experiments on synthesized examples are consistent with these complexity results.

    Place, publisher, year, edition, pages
    Berlin: Springer, 2006
    Series
    Lecture notes in computer science, ISSN 0302-9743
    Keyword
    Test generation, Algorithm complexity, Modeling, Equivalence classes, Deterministic automaton, Data type, Transmission protocol, Finite automaton, Regular language, Inference, Software development
    National Category
    Computer and Information Science
    Identifiers
    urn:nbn:se:uu:diva-98084 (URN)3-540-33093-3 (ISBN)
    Available from: 2009-02-06 Created: 2009-02-06 Last updated: 2009-09-29Bibliographically approved
    4. Regular Inference for State Machines Using Domains with Equality Tests
    Open this publication in new window or tab >>Regular Inference for State Machines Using Domains with Equality Tests
    2008 (English)In: Fundamental Approaches to Software Engineering / [ed] Fiadeiro JL; Inverardi P, Berlin: Springer-Verlag , 2008, 317-331 p.Conference paper, Published paper (Refereed)
    Abstract [en]

    Existing algorithms for regular inference (aka automata learning) allows to infer a finite state machine by observing the output that the machine produces in response to a selected sequence of input strings. We generalize regular inference techniques to infer a class of state machines with an infinite state space. We consider Mealy machines extended with state variables that can assume values from a potentially unbounded domain. These values can be passed as parameters in input and output symbols, and can be used in tests for equality between state variables and/or message parameters. This is to our knowledge the first extension of regular inference to infinite-state systems. We intend to use these techniques to generate models of communication protocols from observations of their input-output behavior. Such protocols often have parameters that represent node adresses, connection identifiers, etc. that have a large domain, and on which test for equality is the only meaningful operation. Our extension consists of two phases. In the first phase we apply an existing inference technique for finite-state Mealy machines to generate a model for the case that the values are taken from a small data domain. In the second phase we transform this finite-state Mealy machine into an infinite-state Mealy machine by folding it into a compact symbolic form.

    Place, publisher, year, edition, pages
    Berlin: Springer-Verlag, 2008
    Series
    Lecture Notes in Computer Science, 4961
    National Category
    Computer Science
    Identifiers
    urn:nbn:se:uu:diva-98085 (URN)10.1007/978-3-540-78743-3_24 (DOI)000254603000024 ()978-3-540-78742-6 (ISBN)
    Conference
    11th International Conference on Fundamental Approaches to Software Engineering Budapest, HUNGARY, MAR 29-APR 06, 2008
    Available from: 2009-02-06 Created: 2009-02-06 Last updated: 2011-03-24Bibliographically approved
    5. Regular Inference for Communication Protocol Entities
    Open this publication in new window or tab >>Regular Inference for Communication Protocol Entities
    2008 (English)Report (Other academic)
    Series
    Technical report / Department of Information Technology, Uppsala University, ISSN 1404-3203 ; 2008-024
    Identifiers
    urn:nbn:se:uu:diva-98086 (URN)
    Available from: 2009-02-06 Created: 2009-02-06 Last updated: 2009-06-09Bibliographically approved
  • 35. Bollig, Benedikt
    et al.
    Leucker, Martin
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Mathematics and Computer Science, Department of Information Technology. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Mathematics and Computer Science, Department of Information Technology, Computer Systems. Datorteknik.
    Deciding LTL over Mazurkiewicz traces2003In: Data & Knowledge Engineering, ISSN 0169-023X, Vol. 44, no 2, 221-240 p.Article in journal (Refereed)
  • 36. Bollig, Benedikt
    et al.
    Leucker, Martin
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Mathematics and Computer Science, Department of Information Technology. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Mathematics and Computer Science, Department of Information Technology, Computer Systems. Datorteknik.
    Model checking probabilistic distributed systems2003In: ASIAN 2003: Proceedings of the 8th Asian Computing Science Conference, 2003, 291-304 p.Conference paper (Refereed)
  • 37.
    Bor, Martin
    et al.
    Lancaster University.
    Roedig, Utz
    Lancaster University.
    Voigt, Thiemo
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Architecture and Computer Communication.
    Alonso, Juan
    Univ. Nac. de Cuyo, Argentina.
    Do LoRa Low-Power Wide-Area Networks Scale?2016Conference paper (Refereed)
    Abstract [en]

    New Internet of Things (IoT) technologies such as LongRange (LoRa) are emerging which enable power ecientwireless communication over very long distances. Devicestypically communicate directly to a sink node which removesthe need of constructing and maintaining a complex multi-hop network. Given the fact that a wide area is coveredand that all devices communicate directly to a few sinknodes a large number of nodes have to share the commu-nication medium. LoRa provides for this reason a rangeof communication options (centre frequency, spreading fac-tor, bandwidth, coding rates) from which a transmitter canchoose. Many combination settings are orthogonal and pro-vide simultaneous collision free communications. Neverthe-less, there is a limit regarding the number of transmitters aLoRa system can support. In this paper we investigate thecapacity limits of LoRa networks. Using experiments wedevelop models describing LoRa communication behaviour.We use these models to parameterise a LoRa simulation tostudy scalability. Our experiments show that a typical smartcity deployment can support 120 nodes per 3.8 ha, which isnot sucient for future IoT deployments. LoRa networkscan scale quite well, however, if they use dynamic commu-nication parameter selection and/or multiple sinks.

  • 38.
    Borgström, Gustaf
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Architecture and Computer Communication.
    Sembrant, Andreas
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Architecture and Computer Communication.
    Black-Schaffer, David
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Architecture and Computer Communication.
    Adaptive cache warming for faster simulations2017In: Proc. 9th Workshop on Rapid Simulation and Performance Evaluation: Methods and Tools, New York: ACM Press, 2017, 1Conference paper (Refereed)
  • 39.
    Brundin, Michelle
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences.
    Morris, Peter
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences.
    Åhlman, Gustav
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences.
    Rosén, Emil
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences.
    Implementation av webbsida för rekommendationssystem med användaruppbyggd databas2012Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The goal of this project was to create a web-based, crowd-sourced, correlational database, that easily allowed users to submit objects and receive correlated objects as results. The webservice was created in the web development languages of HTML, CSS, PHP and Javscript, with MySQL to handle the database. Simultaneous development was kept in check with the aid of the source code management system GIT. Upon completion, the service contained several HTML-views, the ability to add and rate objects, a per-object dedicated page with information parsed from Wikipedia.org, and a view with objects ranked in accordance to the preferences specific to the current user. Roughly a month after the beginning of development, the website was publicly launched and promoted in order to collect data, and improvements were added to the website as needed. Two weeks after the public launch, the collected data was measured and analyzed. The algorithm proved effective and scalable, especially with the introduction of tags and simultaneous computation of object features.

  • 40.
    Carbone, Marco
    et al.
    IT Univ Copenhagen, Rued Langgaards Vej 7, DK-2300 Copenhagen, Denmark..
    Hildebrandt, Thomas
    IT Univ Copenhagen, Rued Langgaards Vej 7, DK-2300 Copenhagen, Denmark..
    Parrow, Joachim
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computing Science.
    Weidlich, Matthias
    Humboldt Univ, Unter Linden 6, D-10099 Berlin, Germany..
    Extended versions of papers presented at WS-FM 2014 and Beat 20142016In: Formal Aspects of Computing, ISSN 0934-5043, E-ISSN 1433-299X, Vol. 28, no 4, 529-530 p.Article in journal (Other academic)
  • 41.
    Carlson, Trevor E.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Architecture and Computer Communication.
    Heirman, Wim
    Intel, ExaSci Lab, Santa Clara, CA USA..
    Allam, Osman
    Univ Ghent, B-9000 Ghent, Belgium..
    Kaxiras, Stefanos
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Architecture and Computer Communication.
    Eeckhout, Lieven
    Univ Ghent, B-9000 Ghent, Belgium..
    The Load Slice Core Microarchitecture2015In: 2015 ACM/IEEE 42Nd Annual International Symposium On Computer Architecture (ISCA), 2015, 272-284 p.Conference paper (Refereed)
    Abstract [en]

    Driven by the motivation to expose instruction-level parallelism (ILP), microprocessor cores have evolved from simple, in-order pipelines into complex, superscalar out-of-order designs. By extracting ILP, these processors also enable parallel cache and memory operations as a useful side-effect. Today, however, the growing off-chip memory wall and complex cache hierarchies of many-core processors make cache and memory accesses ever more costly. This increases the importance of extracting memory hierarchy parallelism (MHP), while reducing the net impact of more general, yet complex and power-hungry ILP-extraction techniques. In addition, for multi-core processors operating in power- and energy-constrained environments, energy-efficiency has largely replaced single-thread performance as the primary concern. Based on this observation, we propose a core microarchitecture that is aimed squarely at generating parallel accesses to the memory hierarchy while maximizing energy efficiency. The Load Slice Core extends the efficient in-order, stall-on-use core with a second in-order pipeline that enables memory accesses and address-generating instructions to bypass stalled instructions in the main pipeline. Backward program slices containing address-generating instructions leading up to loads and stores are extracted automatically by the hardware, using a novel iterative algorithm that requires no software support or recompilation. On average, the Load Slice Core improves performance over a baseline in-order processor by 53% with overheads of only 15% in area and 22% in power, leading to an increase in energy efficiency (MIPS/Watt) over in-order and out-of-order designs by 43% and over 4.7x, respectively. In addition, for a power- and area-constrained many-core design, the Load Slice Core outperforms both in-order and out-of-order designs, achieving a 53% and 95% higher performance, respectively, thus providing an alternative direction for future many-core processors.

  • 42.
    Ceballos, Germán
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Architecture and Computer Communication.
    Grass, Thomas
    Hugo, Andra
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Architecture and Computer Communication.
    Black-Schaffer, David
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Architecture and Computer Communication.
    TaskInsight: Understanding task schedules effects on memory and performance2017In: Proc. 8th International Workshop on Programming Models and Applications for Multicores and Manycores, New York: ACM Press, 2017, 11-20 p.Conference paper (Refereed)
  • 43. Cebrian, Juan M.
    et al.
    Sanchez, Daniel
    Aragon, Juan L.
    Kaxiras, Stefanos
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Efficient inter-core power and thermal balancing for multicore processors2013In: Computing, ISSN 0010-485X, E-ISSN 1436-5057, Vol. 95, no 7, 537-566 p.Article in journal (Refereed)
    Abstract [en]

    Nowadays the market is dominated by processor architectures that employ multiple cores per chip. These architectures have different behavior depending on the applications running on the processor (parallel, multiprogrammed, sequential), but all happen to meet what is called the power and temperature wall. For future technologies (less than 22 nm) and a fixed die size, it is still uncertain the percentage of processor that can be simultaneously powered on. Power saving and power budget mechanisms can be useful to precisely control the amount of power been dissipated by the processor. After an initial analysis we discover that legacy power saving techniques work properly for matching a power budget in thread-independent and multi-programmed workloads, but not in parallel workloads. When running parallel shared-memory applications sacrificing some performance in a single core (thread) in order to be more energy-efficient can unintentionally delay the rest of cores (threads) due to synchronization points (locks/barriers), having a negative impact on global performance. In order to solve this problem we propose power token balancing (PTB) aimed at accurately matching an external power constraint by balancing the power consumed among the different cores. Experimental results show that PTB matches more accurately a predefined power budget (50 % of the original peak power) than other mechanisms like DVFS. The total energy consumed over the budget is reduced to only 8 % for a 16-core CMP with only a 3 % energy increase (overhead). We also introduce a novel mechanism named "Nitro". Nitro will overclock the core that enters a critical section (delimited by locks) in order to free the lock as soon as possible. Experimental results have shown that Nitro is able to reduce the execution time of lock-intensive applications in more than 4 % by overclocking the frequency by 15 % in selected program phases over a period of time that represents a 22 % of the total execution time. We conclude the work with an analysis of the thermal effects of PTB in different CMP configurations using realistic power numbers and heatsink/fan configurations. Results show how PTB not only balances temperature between the different cores, reducing temperature gradient and increasing signal reliability, but also allows a reduction of 28-30 % of both average and peak temperatures for the studied benchmarks when a peak power budget of 50 % is exceeded.

  • 44. Cebrian, Juan M.
    et al.
    Sanchez, Daniel
    Aragon, Juan L.
    Kaxiras, Stefanos
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Managing power constraints in a single-core scenario through power tokens2014In: Journal of Supercomputing, ISSN 0920-8542, E-ISSN 1573-0484, Vol. 68, no 1, 414-442 p.Article in journal (Refereed)
    Abstract [en]

    Current microprocessors face constant thermal and power-related problems during their everyday use, usually solved by applying a power budget to the processor/core. Dynamic voltage and frequency scaling (DVFS) has been an effective technique that allowed microprocessors to match a predefined power budget. However, the continuous increase of leakage power due to technology scaling along with low resolution of DVFS makes it less attractive as a technique to match a predefined power budget as technology goes to deep-submicron. In this paper, we propose the use of microarchitectural techniques to accurately match a power constraint while maximizing the energy-efficiency of the processor. We will predict the processor power dissipation at cycle level (power token throttling) or at a basic block level (basic block level mechanism), using the dissipated power translated into tokens to select between different power-saving microarchitectural techniques. We also introduce a two-level approach in which DVFS acts as a coarse-grain technique to lower the average power dissipation towards the power budget, while microarchitectural techniques focus on removing the numerous power spikes. Experimental results show that the use of power-saving microarchitectural techniques in conjunction with DVFS is up to six times more precise, in terms of total energy consumed over the power budget, than only using DVFS to match a predefined power budget.

  • 45. Cebrián, Juan M.
    et al.
    Aragón, Juan L.
    García, José M.
    Kaxiras, Stefanos
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Leakage-efficient design of value predictors through state and non-state preserving techniques2011In: Journal of Supercomputing, ISSN 0920-8542, E-ISSN 1573-0484, Vol. 55, no 1, 28-50 p.Article in journal (Refereed)
  • 46. Cebrián, Juan M.
    et al.
    Aragón, Juan L.
    Kaxiras, Stefanos
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Power Token Balancing: Adapting CMPs to power constraints for parallel multithreaded workloads2011In: Proc. 25th International Parallel and Distributed Processing Symposium, Piscataway, NJ: IEEE , 2011, 431-442 p.Conference paper (Refereed)
  • 47. Cebrián, Juan M.
    et al.
    Fernández-Pascual, Ricardo
    Jimborean, Alexandra
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Architecture and Computer Communication.
    Acacio, Manuel E.
    Ros, Alberto
    A dedicated private-shared cache design for scalable multiprocessors2017In: Concurrency and Computation, ISSN 1532-0626, E-ISSN 1532-0634, Vol. 29, no 2, e3871Article in journal (Refereed)
  • 48.
    Clear, Tony
    et al.
    Auckland Univ Technol, Sch Engn Comp & Math Sci, Auckland, New Zealand..
    Beecham, Sarah
    Univ Limerick, Lero, Limerick, Ireland..
    Barr, John
    Ithaca Coll, Ithaca, NY 14850 USA..
    Daniels, Mats
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Oudshoorn, Michael
    Wentworth Inst Technol, Dept Comp Sci & Comp Networking, Boston, MA USA..
    Noll, John
    Univ Limerick, Lero, Limerick, Ireland..
    Developments in Global Software Engineering Education2016In: 2016 IEEE FRONTIERS IN EDUCATION CONFERENCE (FIE), 2016Conference paper (Refereed)
    Abstract [en]

    An ITiCSE 2015 conference working group report has recently delivered a comprehensive systematic review of the literature addressing the challenges and solutions in teaching global software engineering courses. In this panel session, a group of authors of that report will review the findings, and present their own views on teaching such courses, the pros and cons and their own motivations and experiences, together with strategies that have proven effective. We argue that these courses are critical for preparing students for practice as software engineers in today's global settings, but they are certainly not for the faint-hearted. After the review and presentation of position statements by panelists there will be a question and answer session with the audience and a discussion elaborating on the next frontiers in research and practice for global software engineering education.

  • 49. Clear, Tony
    et al.
    Daniels, Mats
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Mathematics and Computer Science, Department of Information Technology. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Mathematics and Computer Science, Department of Information Technology, Computer Systems. Datorteknik.
    2D and 3D Introductory Processes in Virtual Groups2003In: IEEE Frontiers in Education, 2003, S1F1-S1F6 p.Conference paper (Refereed)
    Abstract [en]

    This paper reports upon a collaborative learning

    trial conducted in 2002 between students at Auckland

    University of Technology New Zealand and Uppsala

    University Sweden.

    The trial design included an initial phase in which virtual

    groups became acquainted, using different modes of cybericebreaker,

    and a subsequent phase with a common task

    involving group decision making - evaluating and ranking

    the different icebreaker experiences.

    The software used in the trial comprised 1) a custom

    developed web-based groupware database, and 2) a Java

    3D application, employing configurable avatars, which

    could be manipulated in a virtual world. Each of these

    applications supported icebreaking activities intended to

    establish trust between virtual group members, the latter in

    3D mode, and the former in 2D mode.

    The trial process and the software are initially outlined. The

    evaluation strategy, and approaches to data analysis are

    then discussed, and the paper concludes with a report of

    preliminary findings from the trial.

  • 50.
    Cojean, Terry
    et al.
    University of Bordeaux.
    Guermouche, Abdou
    University of Bordeaux.
    Hugo, Andra
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Architecture and Computer Communication.
    Namyst, Raymond
    University of Bordeaux.
    Wacrenier, Pierre-André
    University of Bordeaux.
    Resource aggregation for task-based CholeskyFactorization on top of heterogeneous machines2016Conference paper (Refereed)
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