TY - GEN A1 - Krämer, Stefan T1 - Effects of Arbitrary Hardware Faults on Multicore Scheduling in Safety-critical Applications – Evaluation by enhanced Markov models and discrete event simulation T2 - 2014 PESW - The 2nd Prague Embedded Systems Workshop, June 2014 Y1 - 2014 UR - https://pesw.fit.cvut.cz/2014/presentations/pesw2014_Kramer.pdf ER - TY - JOUR A1 - Joblin, Mitchell A1 - Apel, Sven A1 - Mauerer, Wolfgang T1 - Evolutionary trends of developer coordination: a network approach JF - Empirical Software Engineering N2 - Software evolution is a fundamental process that transcends the realm of technical artifacts and permeates the entire organizational structure of a software project. By means of a longitudinal empirical study of 18 large open-source projects, we examine and discuss the evolutionary principles that govern the coordination of developers. By applying a network-analytic approach, we found that the implicit and self-organizing structure of developer coordination is ubiquitously described by non-random organizational principles that defy conventional software-engineering wisdom. In particular, we found that: (a) developers form scale-free networks, in which the majority of coordination requirements arise among an extremely small number of developers, (b) developers tend to accumulate coordination requirements with more and more developers over time, presumably limited by an upper bound, and (c) initially developers are hierarchically arranged, but over time, form a hybrid structure, in which core developers are hierarchically arranged and peripheral developers are not. Our results suggest that the organizational structure of large projects is constrained to evolve towards a state that balances the costs and benefits of developer coordination, and the mechanisms used to achieve this state depend on the project’s scale. KW - Developer coordination KW - Developer networks KW - Software evolution Y1 - 2016 U6 - https://doi.org/10.1007/s10664-016-9478-9 VL - 22 IS - 4 SP - 2050 EP - 2094 PB - Springer ER - TY - CHAP A1 - Bauer, Gregor A1 - Grossmann, Benjamin A1 - Schlegl, Thomas A1 - Kobayashi, Hiroshi T1 - Modeling, identification and control of an antagonistically actuated joint for telerobotic systems T2 - IECON 2015 - 41st Annual Conference of the IEEE Industrial Electronics Society, 9-12 Nov. 2015, Yokohama, Japan N2 - Within this paper a modeling, identification and control technique for an antagonistically actuated joint consisting of two pneumatically actuated muscles is presented. The antagonistically actuated joint acts as a test bench for control architectures which are going to be used to control an exoskeleton within a telerobotic system. A static and dynamic model of the muscle and the joint is derived and the parameters of the models are identified using a least-squares algorithm. The control architecture, consisting of a inner pressure and an outer position controller is presented. The pressure controller is evaluated using switching valves compared against proportional valves. KW - DYNAMICS KW - FORCE KW - Muscles KW - Telerobotics KW - Torque KW - Valves Y1 - 2015 U6 - https://doi.org/10.1109/IECON.2015.7392676 SP - 3696 EP - 3701 PB - IEEE ER - TY - CHAP A1 - Ramsauer, Ralf A1 - Kiszka, Jan A1 - Lohmann, Daniel A1 - Mauerer, Wolfgang T1 - Look Mum, no VM Exits! (Almost) T2 - Proceedings of the 13th Annual Workshop on Operating Systems Platforms for Embedded Real-Time Applications (OSPERT '17) N2 - Multi-core CPUs are a standard component in many modern embedded systems. Their virtualisation extensions enable the isolation of services, and gain popularity to implement mixed-criticality or otherwise split systems. We present Jailhouse, a Linux-based, OS-agnostic partitioning hypervisor that uses novel architectural approaches to combine Linux, a powerful general-purpose system, with strictly isolated special-purpose components. Our design goals favour simplicity over features, establish a minimal code base, and minimise hypervisor activity. Direct assignment of hardware to guests, together with a deferred initialisation scheme, offloads any complex hardware handling and bootstrapping issues from the hypervisor to the general purpose OS. The hypervisor establishes isolated domains that directly access physical resources without the need for emulation or paravirtualisation. This retains, with negligible system overhead, Linux's feature-richness in uncritical parts, while frugal safety and real-time critical workloads execute in isolated, safe domains. KW - FOS: Computer and information sciences KW - Operating Systems (cs.OS) Y1 - 2017 UR - https://ospert2017.uni.lu/ U6 - https://doi.org/10.48550/arXiv.1705.06932 ER - TY - CHAP A1 - Picha, Petr A1 - Brada, Premek A1 - Ramsauer, Ralf A1 - Mauerer, Wolfgang T1 - Towards Architect’s Activity Detection through a Common Model for Project Pattern Analysis T2 - First International Workshop on the Social and Organization Dimensions of Software, 5-7 April 2017, Gothenburg, Sweden N2 - Software development projects leave a large amount of data in repositories of Application Lifecycle Management (ALM) tools. These data contain detailed histories of their respective projects, their results and decisions made along the way. Analysis of such data helps uncover various interesting facts about projects, e.g. their socio-technical structures and the actual (vs. purported) roles of team members. Based on experiences with tools supporting our research we are convinced that it is feasible to consolidate data from different ALM tools, tapping into the situation common in real-life projects. In this paper we report on our work towards a shared common data model and tool integration aimed at improved project analysis. We discuss how this can help in the identification of architects in the project organizational structures, their activity patterns and collaboration with other team roles. KW - data analysis KW - Data Models KW - project management KW - Software Architecture KW - software tools KW - team working Y1 - 2017 U6 - https://doi.org/10.1109/ICSAW.2017.46 SP - 175 EP - 178 PB - IEEE ER - TY - CHAP A1 - Ramsauer, Ralf A1 - Lohmann, Daniel A1 - Mauerer, Wolfgang ED - Wassermann, Tony T1 - Observing Custom Software Modifications: A Quantitative Approach of Tracking the Evolution of Patch Stacks T2 - Proceedings of the 12th International Symposium on Open Collaboration (OpenSym '16) N2 - Modifications to open-source software (OSS) are often provided in the form of "patch stacks" -- sets of changes (patches) that modify a given body of source code. Maintaining patch stacks over extended periods of time is problematic when the underlying base project changes frequently. This necessitates a continuous and engineering-intensive adaptation of the stack. Nonetheless, long-term maintenance is an important problem for changes that are not integrated into projects, for instance when they are controversial or only of value to a limited group of users. We present and implement a methodology to systematically examine the temporal evolution of patch stacks, track non-functional properties like integrability and maintainability, and estimate the eventual economic and engineering effort required to successfully develop and maintain patch stacks. Our results provide a basis for quantitative research on patch stacks, including statistical analyses and other methods that lead to actionable advice on the construction and long-term maintenance of custom extensions to OSS. KW - CADOS KW - collaboration KW - Linux KW - maintenance KW - patch stacks Y1 - 2016 U6 - https://doi.org/10.1145/2957792.2957810 SP - 1 EP - 4 PB - ACM CY - New York ER - TY - CHAP A1 - Joblin, Mitchell A1 - Mauerer, Wolfgang A1 - Apel, Sven A1 - Siegmund, Janet A1 - Riehle, Dirk T1 - From Developer Networks to Verified Communities: A Fine-Grained Approach T2 - 2015 IEEE/ACM 37th IEEE International Conference on Software Engineering, 16-24 May 2015, Florence, Italy N2 - Effective software engineering demands a coordinated effort. Unfortunately, a comprehensive view on developer coordination is rarely available to support software-engineering decisions, despite the significant implications on software quality, software architecture, and developer productivity. We present a fine-grained, verifiable, and fully automated approach to capture a view on developer coordination, based on commit information and source-code structure, mined from version-control systems. We apply methodology from network analysis and machine learning to identify developer communities automatically. Compared to previous work, our approach is fine-grained, and identifies statistically significant communities using order-statistics and a community-verification technique based on graph conductance. To demonstrate the scalability and generality of our approach, we analyze ten open-source projects with complex and active histories, written in various programming languages. By surveying 53 open-source developers from the ten projects, we validate the authenticity of inferred community structure with respect to reality. Our results indicate that developers of open-source projects form statistically significant community structures and this particular view on collaboration largely coincides with developers' perceptions of real-world collaboration. KW - collaboration KW - Computer languages KW - Measurement KW - Open Source Software KW - Software systems KW - Standards Y1 - 2015 SN - 978-1-4799-1934-5 U6 - https://doi.org/10.1109/icse.2015.73 SP - 563 EP - 573 PB - IEEE ER - TY - GEN A1 - Mauerer, Wolfgang T1 - Open Source in Research and Reality T2 - Open Source Summit North America and Embedded Linux Conference North America 2020 Y1 - 2020 UR - https://www.youtube.com/watch?v=L2iubyD1e7U ER - TY - VIDEO A1 - Mauerer, Wolfgang A1 - Wagner, Daniel T1 - Cyclic Tests Unleashed: Large-Scale RT Analysis with Jitterdebugger T2 - Open Source Summit, North America, 17.07.2019 Y1 - 2019 UR - https://www.youtube.com/watch?v=wNQ24TFjzCw ER - TY - GEN A1 - Ramsauer, Ralf A1 - Duda, Sebastian A1 - Mauerer, Wolfgang A1 - Bulwahn, Lukas T1 - The list is our process: An analysis of the kernel’s email-based development process T2 - Linux Plumbers Conference, Lisbon September 9, 2019 Y1 - 2019 UR - https://www.youtube.com/watch?v=QG1YDQ1HOKE ER - TY - VIDEO A1 - Mauerer, Wolfgang A1 - Ramsauer, Ralf T1 - Torturing Git for Fun and Profit T2 - Microsoft Developer Meetup Regensburg 02.04.2019 N2 - In diesem Talk blicken Prof. Dr. Wolfgang Mauerer und Ralf Ramsauer unter die Haube des verteilten Versionskontrollsystems Git. Neben einer genauen Beschreibung der Strukturen und Plumbing APIs, mit denen Git intern Commits erzeugt und verknüpft, gehen die Vortragenden auch auf nützliche Features und Standards ein, welche die Kollaborition in großen Open-Source Projekten erleichtern. Y1 - 2019 UR - https://www.youtube.com/watch?v=CrUwmO4tvLI ER - TY - CHAP A1 - Mauerer, Wolfgang T1 - Are any big brothers watching you, and if yes, what can they tell about Debian T2 - DebConf18 Hsinchu, Taiwan N2 - Debian, as a collection of software packages and components, is known to be one of the largest software projects in the history of mankind. Combined with a traceable history over many years, the artefacts created by Debian developers and users make it one of science’s favourite targets to quantitatively or qualitatively understand how real-world software development works (or does not), how people collaborate, and many other other related questions. Unfortunately, while scientists make ample use of the resources and artefacts created by FLOSS and friends, the exchange of insights and ideas does not seem to extend in both directions: Developers, users and integrators are often unaware of results obtained in science. This talk will introduce the Debian community to a selection the most important results obtained by scientific (software engineering) research, with a special focus on large-scale socio-technical analysis of projects like Debian, and the possible implications and improvements these may bring to Debian development itself. Y1 - 2018 UR - https://meetings-archive.debian.net/pub/debian-meetings/2018/DebConf18/2018-08-03/are-any-big-brothers-watching-you-and-if.webm ER - TY - GEN A1 - Mauerer, Wolfgang T1 - Embedded Linux Quality Assurance: How to Not Lie with Statistics T2 - Embedded Linux Conference North America ; OpenIoTSummit North America N2 - Embedded Linux drives an every-increasing number of appliances in many domains and applications, some even real-time and/or safety critical. Traditional quality assurance of such systems is based on testing and formal verification, but the huge amount of code and the rapid dynamics of the Linux ecosystem, as well as fundamental limitations of formal methods make these approaches unsatisfactory. Statistical quality assurance for reliability, error rates, maximal latencies etc. is needed. We will discuss current best practises, how to design and run automated statistical tests that capture relevant information, and how to properly evaluate the resulting data. Practical real-world examples and recipes are played through using the open source R language. Most importantly, we identify common mistakes in (over-)interpreting statistical results and predictions that may eventually harm people. Y1 - 2018 UR - https://www.youtube.com/watch?v=8671RYrsAj4 ER - TY - GEN A1 - Ramsauer, Ralf A1 - Kiszka, Jan A1 - Mauerer, Wolfgang T1 - Spectre and Meltdown vs. Real-Time: How Much do Mitigations Cost? T2 - Embedded Linux Conference Europe 2018, October 22 - 24, 2018, Edinburgh, UK Y1 - 2018 UR - https://www.youtube.com/watch?v=nqU4j2M_Ul4 ER - TY - GEN A1 - Ramsauer, Ralf A1 - Kiszka, Jan A1 - Mauerer, Wolfgang T1 - Building Mixed Criticality Linux Systems with the Jailhouse Hypervisor T2 - Embedded Lunux Conference + OpenIoTSummit, Portland, OR, 21.-23.02.2017 N2 - The partitioning hypervisor Jaihouse allows us to run safety critical and uncritical applications in parallel on a single SoC. We present our experiences when porting a safety and real-time critical existing application as a Jailhouse guest. It shows a novel and promising approach for implementing mixed-criticality applications with real-time requirement while not loosing the benefits of Linux. This is done by static partitioning of hardware resources; guests do not interfere. We will present a multicopter platform running the real-time critical flight stack in an isolated Jailhouse guest. This proves the practicability of Jailhouse as well as the suitability for real-time safety critical systems by porting an existing application to a Jailhouse cell. We stress its concept and show up current hardware limitations, like undesired behaviour and present possible workarounds and solutions. Y1 - 2017 UR - https://www.youtube.com/watch?v=pvs0fv-gnvw ER - TY - CHAP A1 - Murr, Florian A1 - Mauerer, Wolfgang T1 - McFSM: Globally Taming Complex Systems T2 - 2017 IEEE/ACM 3rd International Workshop on Software Engineering for Smart Cyber-Physical Systems (SEsCPS), 21-21 May 2017, Buenos Aires, Argentina N2 - Industrial computing devices, in particular cyber-physical, real-time and safety-critical systems, focus on reacting to external events and the need to cooperate with other devices to create a functional system. They are often implemented with languages that focus on a simple, local description of how a component reacts to external input data and stimuli. Despite the trend in modern software architectures to structure systems into largely independent components, the remaining interdependencies still create rich behavioural dynamics even for small systems. Standard and industrial programming approaches do usually not model or extensively describe the global properties of an entire system. Although a large number of approaches to solve this dilemma have been suggested, it remains a hard and error-prone task to implement systems with complex interdependencies correctly. We introduce multiple coupled finite state machines (McFSMs), a novel mechanism that allows us to model and manage such interdependencies. It is based on a consistent, well-structured and simple global description. A sound theoretical foundation is provided, and associated tools allow us to generate efficient low-level code in various programming languages using model-driven techniques. We also present a domain specific language to express McFSMs and their connections to other systems, to model their dynamic behaviour, and to investigate their efficiency and correctness at compile-time. Y1 - 2017 U6 - https://doi.org/10.1109/SEsCPS.2017.7 SP - 26 EP - 29 PB - IEEE ER - TY - GEN A1 - Mauerer, Wolfgang T1 - Safety, Security, Quality: Artificial Intelligence versus Common Sense T2 - Open Source Summit North America and Embedded Linux Conference North America 2020 Y1 - 2020 UR - https://www.youtube.com/watch?v=Ow_tMneQlH4 UR - https://elinux.org/images/7/7d/Wolfgang_Mauerer.pdf ER - TY - GEN A1 - Mauerer, Wolfgang A1 - Wagner, Daniel T1 - Cyclic Tests Unleashed: Large-Scale RT Analysis with Jitterdebugger T2 - Open Source Summit Japan (Tokio) and OSSNA 17.07.2019 Y1 - 2019 UR - https://events19.linuxfoundation.org/wp-content/uploads/2018/07/talk.pdf ER - TY - GEN A1 - Ramsauer, Ralf A1 - Duda, Sebastian A1 - Bulwahn, Lukas A1 - Mauerer, Wolfgang T1 - The list is our process! An analysis of the kernel’s email-based development process T2 - Embedded Linux Conference Europe, Lyon 28.10.2019 Y1 - 2019 UR - https://elinux.org/images/0/09/Pasta-elce19.pdf ER - TY - GEN A1 - Ramsauer, Ralf A1 - Kiszka, Jan A1 - Lohmann, Daniel A1 - Mauerer, Wolfgang T1 - Implementierung gemischt kritischer Systeme durch statische Hardwarepartitionierung T2 - Frühjahrstreffen der Fachgruppen Betriebssysteme, Hannover, 2. März 2018 Y1 - 2018 UR - https://www.betriebssysteme.org/wp-content/uploads/2018/04/fgbs18-169.pdf ER -