| 21. |
- Lo Bello, L., et al.
(författare)
-
Schedulability analysis of Time-Sensitive Networks with scheduled traffic and preemption support
- 2020
-
Ingår i: Journal of Parallel and Distributed Computing. - : Academic Press Inc.. - 0743-7315 .- 1096-0848. ; 144, s. 153-171
-
Tidskriftsartikel (refereegranskat)abstract
- The Time-Sensitive Networking (TSN) set of standards introduces in IEEE 802.1 switches and end stations novel features to meet the requirements of a broad spectrum of applications that are characterized by time-sensitive and mission-critical traffic flows. In particular, the IEEE802.1Qbv-2015 amendment introduces enhancements that provide temporal isolation for scheduled traffic, i.e., a traffic class that requires transmission based on a known timescale, while the IEEE802.1Qbu-2016 introduces preemption as a mechanism to allow time-critical messages to interrupt ongoing non time-critical transmissions. Both amendments, that are now enrolled in the IEEE802.1Q-2018 standard, are very important for industrial networks, where scheduled traffic and low-latency real-time flows have to coexist, on the same network, with best-effort transmissions. In this context, this work presents a response time analysis of TSN networks that encompasses the enhancements for scheduled traffic and preemption, in various combinations. The paper presents the proposed analysis and a performance comparison between the response times calculated by the analysis and the response times obtained through OMNeT++ simulations in three different scenarios. © 2020 Elsevier Inc.
|
|
| 22. |
- Seceleanu, Cristina, 1968-, et al.
(författare)
-
Assured Cloud Platforms for Industrial Cyber-Physical Systems : The ACICS Approach
- 2021
-
Ingår i: ACM International Conference Proceeding Series. - New York, NY, USA : Association for Computing Machinery. - 9781450390576
-
Konferensbidrag (refereegranskat)abstract
- With the emergence of "Industry 4.0", the integration of cloud technologies and industrial cyber-physical systems becomes increasingly important to boost productivity. The industrial cyber-physical systems infrastructures and their fusion with the cloud lead to massive amounts of data acquired for controlling particular processes, but also for supporting decision-making. Although cloud-assisted systems are increasingly important in many domains, and ensuring their dependability is crucial, existing platforms do not provide satisfactory support to meet the dependability demands of industrial applications. The overall goal of the ACICS project is to provide models, methods and tools that facilitate a substantial increase of dependability of cloud-based platforms for industrial cyber-physical applications, with respect to consistency, security and interoperability of data, timing predictability of using shared virtual resources, together with a framework of guaranteeing quality-of-service enforcement by formal analysis and verification. In this paper, we present the main conceptual ideas behind the ACICS approach.
|
|
| 23. |
- Struhar, Vaclav
(författare)
-
Improving Soft Real-time Performance of Fog Computing
- 2021
-
Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Fog computing is a distributed computing paradigm that brings data processing from remote cloud data centers into the vicinity of the edge of the network. The computation is performed closer to the source of the data, and thus it decreases the time unpredictability of cloud computing that stems from (i) the computation in shared multi-tenant remote data centers, and (ii) long distance data transfers between the source of the data and the data centers. The computation in fog computing provides fast response times and enables latency sensitive applications. However, industrial systems require time-bounded response times, also denoted as RT. The correctness of such systems depends not only on the logical results of the computations but also on the physical time instant at which these results are produced. Time-bounded responses in fog computing are attributed to two main aspects: computation and communication. In this thesis, we explore both aspects targeting soft RT applications in fog computing in which the usefulness of the produced computational results degrades with real-time requirements violations. With regards to the computation, we provide a systematic literature survey on a novel lightweight RT container-based virtualization that ensures spatial and temporal isolation of co-located applications. Subsequently, we utilize a mechanism enabling RT container-based virtualization and propose a solution for orchestrating RT containers in a distributed environment. Concerning the communication aspect, we propose a solution for a dynamic bandwidth distribution in virtualized networks.
|
|
| 24. |
- Struhar, Vaclav, et al.
(författare)
-
REACT : Enabling Real-Time Container Orchestration
- 2021
-
Konferensbidrag (refereegranskat)abstract
- Fog and edge computing offer the flexibility and decentralized architecture benefits of cloud computing without suffering from the latency issues inherent in the cloud. This makes fog computing very attractive in real-time and safety-critical applications, especially if combined with container-based technologies. Whereas different orchestration systems are available to manage the container placement based on their resource demand, no orchestration system is considering real-time requirements for containerized applications. In this paper, we present the architecture and design of a real-time container orchestrator based on Kubernetes. Moreover, this paper defines metrics for the performance evaluation of real-time containers and describes an initial model for allocating a mixture of real-time and non-real-time containers. We present an initial implementation of our real-time container extension and evaluate its feasibility on Linux-based systems.
|
|
| 25. |
- Struhar, Vaclav, et al.
(författare)
-
Real-time containers : A survey
- 2020
-
Ingår i: OpenAccess Series in Informatics. - : Schloss Dagstuhl- Leibniz-Zentrum fur Informatik GmbH, Dagstuhl Publishing. - 9783959771443
-
Konferensbidrag (refereegranskat)abstract
- Container-based virtualization has gained a significant importance in a deployment of software applications in cloud-based environments. The technology fully relies on operating system features and does not require a virtualization layer (hypervisor) that introduces a performance degradation. Container-based virtualization allows to co-locate multiple isolated containers on a single computation node as well as to decompose an application into multiple containers distributed among several hosts (e.g., in fog computing layer). Such a technology seems very promising in other domains as well, e.g., in industrial automation, automotive, and aviation industry where mixed criticality containerized applications from various vendors can be co-located on shared resources. However, such industrial domains often require real-time behavior (i.e, a capability to meet predefined deadlines). These capabilities are not fully supported by the container-based virtualization yet. In this work, we provide a systematic literature survey study that summarizes the effort of the research community on bringing real-time properties in container-based virtualization. We categorize existing work into main research areas and identify possible immature points of the technology. © Václav Struhár, Moris Behnam, Mohammad Ashjaei, and Alessandro V. Papadopoulos; licensed under Creative Commons License CC-BY 2nd Workshop on Fog Computing and the IoT (Fog-IoT 2020).
|
|
| 26. |
- Struhar, Vaclav, et al.
(författare)
-
Resource Adaptation for Real-Time Containers Considering Quality of Control
- 2023
-
Ingår i: IEEE Int. Conf. Emerging Technol. Factory Autom., ETFA. - : Institute of Electrical and Electronics Engineers Inc.. - 9798350339918
-
Konferensbidrag (refereegranskat)abstract
- Container-based virtualization has become a promising deployment model for industrial applications mainly due to its benefits, such as providing support for co-located applications in heterogeneous environments. However, such facilitation brings challenges, including full temporal isolation among real-time applications and support for time-critical applications. In this paper, we tackle such challenges, in particular when the applications are time-sensitive Control Applications. The literature suggests that flexible timing constraints for Control Applications are beneficial in responding to disturbances and minimizing response deviation. Therefore, we propose a mechanism to support such a runtime adaptation in container-based virtualization. To show the performance of the proposed mechanism, we implement our approach on a Linux-based hierarchical scheduling platform, and we evaluate it for a Control application.
|
|
| 27. |
|
|
| 28. |
- Tsog, Nandinbaatar, et al.
(författare)
-
Offloading Accelerator-intensive Workloads in CPU-GPU Heterogeneous Processors
- 2021
-
Ingår i: 26th IEEE International Conference on Emerging Technologies and Factory Automation, ETFA 2021. - 9781728129891
-
Konferensbidrag (refereegranskat)abstract
- Autonomous vehicular systems require computer vision and intelligent on-board decision making functionalities that include a mix of sequential and parallel workloads. The execution times of the workloads and power consumption in these functionalities can be lowered by utilizing the accelerators (e.g., GPU) instead of running the workloads entirely on the host processing units (CPU). However, allocating all the parallelizable workload to accelerators can create a computation bottleneck in the accelerators that, in turn, can have an adverse effect on schedulability of the systems. This paper presents a novel framework that can allocate the accelerate-intensive workloads to the accelerators as well as to the non-accelerated host processing units. Within the context of this framework, the paper introduces five offloading techniques to mitigate the accelerator-intensive workloads by utilizing excess capacity of non-accelerated processing units under dynamic scheduling in CPU-GPU heterogeneous processors. The proposed techniques are evaluated using simulation experiments. The evaluation results indicate that one of the proposed techniques can achieve up to 16% improvement in schedulability of the task sets compared to the traditional non-offloading technique.
|
|
| 29. |
- Tsog, Nandinbaatar, et al.
(författare)
-
Simulation and Analysis of In-Orbit Applications under Radiation Effects on COTS Platforms
- 2021
-
Ingår i: 42nd IEEE Aerospace Conference 2021 IEEEAC2021.
-
Konferensbidrag (refereegranskat)abstract
- Radiation effects research is crucial as it defines risk to both human bodies and spacecraft. Employing radiation-hardened products is one way to mitigate radiation effects on in-orbit systems. However, radiation effects prohibit most of the state-of-the-art commercial off-the-shelf (COTS) technologies from use in space. Furthermore, radiation effects on software components are less studied compared to hardware components. In this work, we introduce a simulation tool that analyzes the impact of radiation effects on schedulability of task sets executing on COTS system-on-chip (SoC) platforms in the in-orbit systems. In order to provide a meaningful verification environment, single-event effects (SEEs) are introduced as aleatory disturbances characterized by probability distribution of occurrence using their predefined models. The tool supports interoperability with several other tools as it uses the extensible markup language (XML) model files for input and output, i.e., for importing input task sets and radiation effects and exporting the simulation results.
|
|
| 30. |
- Tsog, Nandinbaatar
(författare)
-
Space Computing using COTS Heterogeneous Platforms : Intelligent On-Board Data Processing in Space Systems
- 2021
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Space computing enriches space activities such as deep-space explorations and in-orbit intelligent decision making. The awareness of space computing is growing due to the technological advances of high-performance commercial off-the-shelf (COTS) computing platforms. Space offers a complex, constrained and challengeable environment to the developers, researchers, as well as human beings. The challenges are size, weight and power (SWaP) constraints, real-time requirements, communication limitations as well as radiation effects. The research conducted in this thesis aims at investigating and supporting intelligent on-board data processing using COTS heterogeneous computing platforms in space systems. These platforms embed at least one Central Processing Unit (CPU) and one Graphics Processing Unit (GPU) on the same chip. The main goal of the research presented in this thesis is twofold. First, to investigate the heterogeneous computing platforms for the purpose of proposing a solution to tackle the above-mentioned challenges in space systems. Second, to complement the proposed solution with novel scheduling techniques for real-time applications that run on COTS heterogeneous platforms under harsh environments like space.The proposed techniques are based on the system model that considers the use of alternative executions of parallel segments of tasks. Although offloading a parallel segment to a parallel computation unit (such as GPU) improves the best-case execution times of most applications, it can increase the response times of tasks in some applications due to the overuse of GPU. Hence, the use of the proposed task model can be a key to decrease the response times of tasks and improve schedulability of the system. The server-based proposed scheduling techniques support the proposed task model by guaranteeing the execution slot for parallel segments on CPU(s). The experimental evaluation conducted in this thesis shows that the proposed task model can improve the schedulability of the real-time systems up to 90% with the static allocation of applications. Moreover, the dynamic allocation method using the server-based scheduling with the proposed task model can improve the schedulability up to 16%. Finally, the thesis presents a simulation tool that simulates real-time applications using the proposed task model while considering the different levels of radiation tolerance to different processing units.
|
|
