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Betriebssysteme, Kommunikationssysteme und Verteilte Systeme (SYS)

https://dl.gi.de/handle/20.500.12116/6251
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Auflistung Betriebssysteme, Kommunikationssysteme und Verteilte Systeme (SYS) nach Erscheinungsdatum

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  • Textdokument
    Efficient Checkpointing in Byzantine Fault-Tolerant Systems
    (Tagungsband des FB-SYS Herbsttreffens 2019, 2019) Eischer, Michael; Distler, Tobias
    Distributed Byzantine fault-tolerant systems require frequent checkpoints of the application state to perform periodic garbage collection and enable faulty replicas to recover efficiently. State-of-the-art checkpointing approaches for replicated systems either cause significant service disruption when the application state is large, or they are unable to produce checkpoints that are verifiable across replicas. To address these problems we developed and evaluated deterministic fuzzy checkpointing, a technique to create consistent and verifiable checkpoints in parallel with request execution.
  • Textdokument
    Systems Support For Efficient State-Machine Replication
    (Tagungsband des FB-SYS Herbsttreffens 2019, 2019) Habiger, Gerhard; Hauck, Franz J.
    State-Machine Replication (SMR) is a well known approach for the deployment of highly fault-tolerant services. Recent research has focused on efficiency improvements, performance optimisation and novel approaches to underlying concepts of SMR, such as consensus with trusted components, dynamic weights for quorums, or parallelisation of application code. To increase adoption of SMR as a basic fault-tolerance technique, we see the need to improve the current state of the art of SMR even further, and provide four specific ways in which our research contributes to this goal. In particular, we present two approaches which make the development and deployment of SMR services both easier and more efficient, and talk about two further areas of improvement concerning internal mechanisms of common SMR architectures. The goal of this paper is to provide our current understanding of important issues of current SMR systems as well as to outline possible future solutions to them.
  • Textdokument
    Towards a Robust, Self-Organizing IoT Platform for Secure and Dependable Service Execution
    (Tagungsband des FB-SYS Herbsttreffens 2019, 2019) Eichhammer, Philipp; Berger, Christian; Reiser, Hans P.; Domaschka, Jörg; Hauck, Franz J.; Habiger, Gerhard; Griesinger, Frank; Pietron, Jakob
    In the IoT, resilience capabilities increasingly gain traction for applications, as IoT systems tend to play a bigger role for both the proper functioning of our society and the survivability of companies. However, hardening IoT service execution against a variety of possible faults and attacks becomes increasingly difficult as the complexity, size and heterogeneity of IoT infrastructures tend to grow further and further. Moreover, many existing solutions only regard either specific faults or security issues instead of following a unifying approach. In this position paper, we present our research project called SORRIR, which essentially is an approach to develop a self-organizing IoT platform for dependable and secure service execution. One of our main ambitions is to support developers by separating application development (app logic) from resilience properties, so that developers can configure a desired resilience degree without proper knowledge of underlying technical, implementation-level details of employed resilience mechanisms. Further, we consider security requirements and properties as an integral component of our platform.
  • Textdokument
    In Microservices We Trust — Do Microservices Solve Resilience Challenges?
    (Tagungsband des FB-SYS Herbsttreffens 2019, 2019) Hilbrich, Marcus
    Resilience is an open challenge. In this paper we look into microservices – a concept that argues to be resilient. We look into the definition of microservices and argue whether the definition provides the promised advantages regarding to resilience.
  • Textdokument
    Group-based Memory Management in Fyr
    (Tagungsband des FG-BS Herbsttreffens 2020, 2020) Weis, Torben; Zdankin, Peter; Carl, Oskar; Waltereit, Marian
    Albeit being introduced decades ago, C and C++ are still the most commonly used programming languages for operating systems. These languages have no reliable mechanisms to deal with memory safety issues, such as use-after-free or data race conditions, that are a leading cause for security bugs in operating systems and other critical software. Tools such as Valgrind have been developed to identify errors, but the errors must occur during the analysis, as they are not found otherwise. Several modern programming languages such as Rust, Go and Swift have emerged aiming to solve some of the issues by providing memory safety guarantees at compile or run time. However, these languages introduce new limitations, especially concerning software development for performance-critical or resource-constrained systems. In this paper, we introduce a new approach to automatic memory management that manages the lifetime of object groups instead of individual objects. We show that group-based memory management can remove some of the restrictions of modern programming languages while satisfying important memory safety constraints. Furthermore, we show how group-based memory management is implemented in our new systems programming language Fyr.
  • Textdokument
    Improving Linux-Kernel Tests for LockDoc with Feedback-driven Fuzzing
    (Tagungsband des FG-BS Herbsttreffens 2020, 2020) Lochmann, Alexander; Thunig, Robin; Schirmeier, Horst
    LockDoc is an approach to extract locking rules for kernel data structures from a dynamic execution trace recorded while the system is under a benchmark load. These locking rules can e.g. be used to locate synchronization bugs. For high rule precision and thorough bug finding, the approach heavily depends on the choice of benchmarks: They must trigger the execution of as much code as possible in the kernel subsystem relevant for the targeted data structures. However, existing test suites such as those provided by the Linux Test Project (LTP) only achieve – in the case of LTP – about 35 percent basic-block coverage for the VFS subsystem, which is the relevant subsystem when extracting locking rules for filesystem-related data structures. In this article, we discuss how to complement the LTP suites to improve the code coverage for our LockDoc scenario. We repurpose syzkaller – a coverage-guided fuzzer with the goal to validate the robustness of kernel APIs – to 1) not aim for kernel crashes, and to 2) maximize code coverage for a specific kernel subsystem. Thereby, we generate new benchmark programs that can be run in addition to the LTP, and increase VFS basic-block coverage by 26.1 percent.
  • Textdokument
    Persistent Streams: The Internet With Ephemeral Storage
    (Tagungsband des FG-BS Herbsttreffens 2021, 2021) Carl, Oskar; Zdankin, Peter; Schaffeld, Matthias; Matkovic, Viktor; Yu, Yang; Elbers, Timo; Weis, Torben
    Communication in the internet today is transient by default. Because of this, whenever an application needs to store data even for a moment, its provider needs to develop an application-specific solution, which is often done using client-server models. This is costly at scale, and generally requires users to concede control over the data they generate to allow application providers to generate revenue from the collected data to finance the operation of these servers. This also leads to a lock-in effect, which is prohibitive for new applications entering a market. To solve these issues, we propose persistent streams, an application-agnostic communication protocol that includes ephemeral and persistent storage and is able to handle both discrete as well as continuous (streaming) data. Including storage into the communication path removes the need for application servers completely. Even though the protocol relies on (cloud) servers as transmission and storage proxies, we expect the emergence of new storage technologies like non-volatile main memory to alleviate some issues this introduces. We also show the general applicability of this solution using different kinds of applications as examples. Overall, persistent streams have the potential to greatly reduce the burdens on application providers while also enabling users to exercise increased control over their data.
  • Textdokument
    Remote AVX Overhead: Detection and Mitigation
    (Tagungsband des FG-BS Frühjahrstreffens 2021, 2021) Gottschlag, Mathias
    Due to power constraints, recent Intel CPUs reduce their frequency when executing AVX2 and AVX-512 instructions. Often, this frequency reduction affects other applications as well, which reduces overall performance and prevents contemporary operating systems from fairly distributing system resources. In our work, we show that these problems are fundamental problems of power-limited computing. We analyze the problems and show a method to quantify the underlying AVX overhead. Based on our analysis, we then describe a set of operating system techniques to improve performance and scheduler fairness. Our results show the importance of active management of hardware-controlled frequency scaling by the OS. Based on this observation, we sketch improved hardware-software interfaces which could further reduce AVX overhead and improve the efficacy of our approach.
  • Textdokument
    Toward Dynamic Orchestration of Data/Power/Process Management for Hybrid Memory Based Systems
    (Tagungsband des FG-BS Herbsttreffens 2021, 2021) Arima, Eishi; Trinitis, Carsten; Schulz, Martin
    The exponential growth of the transistor count on VLSI circuits, known as Moore’s law, is slowing down, and the end of the technology scaling is predicted to be inevitable. As a consequence, computing system architectures are gradually shifting toward extremely heterogeneous designs consisting of multiple different hardware devices or accelerators in each component. As one example, over the past few years the industry has begun to support hybrid memory systems in their products based on emerging memory device technologies, most prominently HBM (High-Bandwidth Memory) and NVRAM (Non-Volatile RAM). This hardware trend has opened up new research opportunities in the system software and operating system area. In this position paper, we focus on data, power and process management in hybrid memory based systems, with a particular focus on a coordinated and dynamic approach. This is based on our key insight, which is brought by our prior studies, that the on such systems memory access/utilization behavior as well as the memory management policy plays an important role for various optimizations, including power management and process (or job) scheduling. In this position paper, we clarify the problem, provide a high-level software architecture, and finally discuss the major challenges to realize it.
  • Textdokument
    Developing Bare-Metal GPGPU Drivers From Scratch: What prevents scientists from developing own GPGPU drivers?
    (Tagungsband des FG-BS Frühjahrstreffens 2021, 2021) Lütke Dreimann, Marcel; Kessener, Daniel
    Most of modern computers use Graphic Processing Units (GPUs) as an additional source of computing power. However, using GPUs in bare-metal research operating systems comes with some challenges. Existing drivers for Linux or Windows are complex and cannot be used for without much effort. Documentation of modern GPUs is often missing or incomplete and drivers are incomprehensive or closed source. This paper tries to explain what prevents scientists from creating their own GPU drivers. Additionally, it gives an overview about GPGPU driver development for GPUs from different manufactur- ers and shows some challenges. Nevertheless, we have ambitiously started an undertaking to develop our own driver from scratch. To some extend this was successful, but with many problems on the way.