| 1. |
- Ciccozzi, Federico, et al.
(författare)
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Generation of Correct-by-Construction Code from Design Models for Embedded Systems
- 2011
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Ingår i: 6th IEEE International Symposium on Industrial Embedded Systems (SIES'11). - : IEEE. - 9781612848181 ; , s. 63-66
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Konferensbidrag (refereegranskat)abstract
- In a model-driven engineering development process that focuses on guaranteeing that extra-functional concerns modeled at design level are preserved at platform execution level, the task of automated code generation must produce artifacts that enable back-annotation activities. In fact when the target platform code has been generated, quality attributes of the system are evaluated by appropriate code execution monitoring/analysis tools and their results back-annotated to the source models to be extensively evaluated. Only at this point the preservation of analysed extra-functional aspects can be either asserted or achieved by re-applying the code generation chain to the source models properly optimized according to the evaluation results. In this work we provide a solution for the problem of automatically generating target platform code from source models focusing on producing code artifacts that facilitate analysis and enable back-annotation activities. Arisen challenges and solutions are described together with completed and planned implementation of the proposed approach.
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| 2. |
- Fredriksson, Johan, et al.
(författare)
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Clustering Worst-Case Execution Times for Software Components
- 2007
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Ingår i: Proceedings of the 7th International Workshop on Worst Case Execution Time Analysis (WCET'07), Pisa, Italy. - 9783939897057 ; , s. 19-25
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Konferensbidrag (refereegranskat)abstract
- For component-based systems, classical techniques for WCET-estimation produce unacceptable overestimations of the WCET. This is because software components have more general behavior in order to support reuse. Existing tools and methods for component-based software engineering (CBSE) do not yet adequately consider reusable analyses.We present a method that allows different WCETs to be associated with subsets of the component behavior by clustering WCETs with respect to behavior. The method is intended to be used for facilitating reusable WCET analysis for reusable software components. We illustrate our technique and demonstrate its potential in achieving tight WCET-estimates for components with rich behavior.
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| 3. |
- Hjertström, Andreas, et al.
(författare)
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INCENSE : Information-Centric Run-Time Support for Component-Based Embedded Real-Time Systems
- 2007
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Ingår i: Proceedings of the Work-In-Progress (WIP) session, 14th IEEE Real-Time and Embedded Technology and Applications Symposium, Seattle, United States. ; , s. 4-
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Konferensbidrag (refereegranskat)abstract
- In this paper we present a technique to allow the use ofreal-time database management together with componentbasedsoftware development, to achieve an information centricrun-time platform for the development of embeddedreal-time systems. The technique allows components tobenefit from the advantages of a real-time database managementsystem while still retaining desirable componentproperties, such as isolation and a high level of reusability.We propose that a database is integrated in the componentframework, and introduce the concept of databaseproxies to decouple components from the database schema.The resulting system fully benefits from the advantages ofcomponent-based software development, such as reusability,all component interaction through interfaces, etc, combinedwith the advantages of a real-time database managementsystem, i.e., system openness, controlled data access,and dynamic query language capabilities.
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| 4. |
- Hänninen, Kaj, et al.
(författare)
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Determining maximum stack usage in preemptive shared stack systems
- 2007. - 1
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Ingår i: Proceedings of the 9th Real-Time in Sweden (RTiS'07), Västerås, Sweden. ; , s. 118-126
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Konferensbidrag (refereegranskat)abstract
- This paper presents a novel method to determine the maximum stack memory used in preemptive, shared stack, real-time systems. We provide a general and exact problem formulation applicable for any preemptive system model based on dynamic (run-time) properties. We also show how to safely approximate the exact stack usage by using static (compile time) information about the system model and the underlying run-time system on a relevant and commercially available system model: A hybrid, statically and dynamically, scheduled system. Comprehensive evaluations show that our technique significantly reduces the amount of stack memory needed compared to existing analysis techniques. For typical task sets a decrease in the order of 70% is typical.
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| 5. |
- Hänninen, Kaj, et al.
(författare)
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Determining maximum stack usage in preemptive shared stack systems
- 2006. - 1
-
Ingår i: Proceedings - Real-Time Systems Symposium. - 9780769527611 ; , s. 445-453
-
Konferensbidrag (refereegranskat)abstract
- This paper presents a novel method to determine the maximum stack memory used in preemptive, shared stack, real-time systems. We provide a general and exact problem formulation applicable for any preemptive system model based on dynamic (run-time) properties. We also show how to safely approximate the exact stack usage by using static (compile time) information about the system model and the underlying run-time system on a relevant and commercially available system model: A hybrid, statically and dynamically, scheduled system. Comprehensive evaluations show that our technique significantly reduces the amount of stack memory needed compared to existing analysis techniques. For typical task sets a decrease in the order of 70% is typical.
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| 6. |
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| 7. |
- Möller, Anders, et al.
(författare)
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Industrial Requirements on Component Technologies for Vehicular Control Systems
- 2006
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Software component technologies for automotive applications are desired due to the envisioned benefits in reuse, variant handling, and porting; thus, facilitating both efficient development and increased quality of software products. Component based software development has had success in the PC application domain, but requirements are different in the embedded domain and existing technologies does not match. Hence, software component technologies have not yet been generally accepted by embedded-systems industries.In order to better understand why this is the case, we present two separate case-studies together with an evaluation of the existing component technologies suitable for embedded control systems.The first case-study presents a set of requirements based on industrial needs, which are deemed decisive for introducing a component technology. Furthermore, in the second study, we asked the companies involved to grade these requirements.Then, we use these requirements to compare existing component technologies suitable for embedded systems. One of our conclusions is that none of the studied technologies is a perfect match for the industrial requirements. Furthermore, no single technology stands out as being a significantly better choice than the others; each technology has its own pros and cons.The results can be used to guide modifications and/or extensions to existing component technologies in order to make them better suited for industrial deployment in the automotive domain. The results can also serve to guide other software engineering research by showing the most desired areas within component-based software engineering.
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| 8. |
- Sjödin, Peter, et al.
(författare)
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CANopen.NET - Programming-less interconnection between GUI- and control-application
- 2006
-
Ingår i: International CAN Conference (iCC), Stockholm.
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Konferensbidrag (refereegranskat)abstract
- We present the novel concept CANopen.NET. In this concept we integrate Windows GUI-programming in .NET and control-applications based on CANopen. The integration is automated, thus no programming is needed.An increasing number of CAN-based systems are equipped with Windows-based graphical user-interfaces (GUIs). Today, the .NET framework provides the most attractive solutions for design of GUIs both i Windows and WindowsCE. However, transferring information between the CANopen-domain (which is typically unmanaged code) and the .NET-domain (managed code) is non trivial. Traditional methods require handwritten pieces of code both in the managed and unmanaged domain for each signal (object-dictionary entry). This means that adding or modifying signals to the system becomes tedious, error-prone and expensive.In .NET high-level abstractions like XML-documents, web-servers and databases are easily accessible and can be bound to graphical controls. Hence, in CANopen.NET we provide a .NET-database interface via the .NET type "dataset" to the data in the object dictionary. This dataset is automatically generated from a CANopen profile-specification (EDS-file). Also, the CANopen-stack is automatically configured from the EDS-file. Hence, CANopen.NET provides a programming-less interconnection between CANopen-based control-applications and Windows.NET-based GUI-applications. This significantly eases the development of CANopen-systems with GUIs.
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| 9. |
- Åkerholm, Mikael, et al.
(författare)
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Handling Subsystems using the SaveComp Component Technology
- 2006
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Ingår i: Workshop on Models and Analysis for Automotive Systems (WMAAS'06) in conjunction with the 27th IEEE Real-Time Systems Symposium (RTSS'06), Rio de Janeiro, Brazil.
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Konferensbidrag (refereegranskat)
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| 10. |
- Åkerholm, Mikael, et al.
(författare)
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The SaveCCM Language Reference Manual
- 2007
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- This language reference describes the syntax and semantics of SaveCCM, acomponent modeling language for embedded systems designed with vehicle applications and safety concerns in focus. The SaveCCM component model wasdefined within the SAVE project. The SAVE components are influenced mainlyby the Rubus component technology, with a switch concept similar to thatin Koala. The semantics is defined by a transformation into timed automatawith tasks, a formalism that explicitly models timing and real-time task scheduling.The purpose of this document is to describe a semantics of the SAVE component modeling language, which can be used to describe timing and functional behavior of components. The model of a system is in some cases an over approximation of the actual system behavior. An implementation of a model can resolve non-determinism e.g. by merging tasks or assigning a scheduling policy (such as static scheduling or fixed priority, preemptive or not) that will resolvethe non-determinism.
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| 11. |
- Aggerstam, Thomas, et al.
(författare)
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AlGaN/GaN high-electron-mobility transistors on sapphire with Fe-doped GaN buffer layer by MOVPE
- 2006
-
Ingår i: Physica Status Solidi C - Current Topics in Solid State Physics. - : Wiley. ; , s. 2373-2376
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Konferensbidrag (refereegranskat)abstract
- A simple AlGaN/GaN HEMT structure without any interlayer on Fe-doped GaN (GaN:Fe) grown by LP-MOVPE in one single run on sapphire is demonstrated. The surface segregation of Fe in GaN occurring during growth is identified. Hall measurements yield 2DEG (two dimensional electron gas) mobilities of 1700 and 10700 cm2/Vs and sheet carrier concentrations of 5.1×10 12 and 5.7×1012 cm-2 at 300 K and 20 K, respectively. Good pinch-off current-voltage (ID-VD) characteristics is observed from AlGaN/GaN HEMTs. A maximum drain current density of 0.6 A/mm and a peak extrinsic transconductance of 200 mS/mm have been observed. The HEMT structure yields very good device isolation as indicated by an isolation current of ≀1 nA at 20 V.
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| 12. |
- Aggerstam, Thomas, et al.
(författare)
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Investigation of the interface properties of MOVPE grown AlGaN/GaN high electron mobility transistor (HEMT) structures on sapphire
- 2006
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Ingår i: Thin Solid Films. - : Elsevier BV. - 0040-6090 .- 1879-2731. ; 515:2, s. 705-707
-
Tidskriftsartikel (refereegranskat)abstract
- We have developed a virtual GaN substrate on sapphire based on a two-step growth method. By optimizing the growth scheme for the virtual substrate we have improved crystal quality and reduced interface roughness. Our Al0.22Ga0.78N/GaN HEMT structure grown on the optimized semi-insulating GaN virtual substrate, exhibits Hall mobilities as high as 1720 and 7350 cm(2)/Vs and sheet carrier concentrations of 8.4 x 1012 and 10.0 x 1012 cm(-2) at 300 K and 20 K, respectively The presence of good AlGaN/GaN interface quality and surface morphology is also substantiated by X-Ray reflectivity and Atomic Force Microscopy measurements. A simplified transport model is used to fit the experimental Hall mobility.
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| 13. |
- Aittamaa, Simon
(författare)
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Programming embedded real-time systems : implementation techniques for concurrent reactive objects
- 2011
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- An embedded system is a computer system that is a part of a larger device with hardware and mechanical parts. Such a system often has limited resources (such as processing power, memory, and power) and it typically has to meet hard real-time requirements. Today, as the area of application of embedded systems is constantly increasing, resulting in higher demands on system performance and a growing complexity of embedded software, there is a clear trend towards multi-core and multi-processor systems. Such systems are inherently concurrent, but programming concurrent systems using the traditional abstractions (i.e., explicit threads of execution) has been shown to be both difficult and error-prone. The natural solution is to raise the abstraction level and make concurrency implicit, in order to aid the programmer in the task of writing correct code. However, when we raise the abstraction level, there is always an inherent cost. In this thesis we consider one possible concurrency model, the concurrent reactive object approach that offers implicit concurrency at the object level. This model has been implemented in the programming language Timber, which primarily targets development of real-time systems. It is also implemented in TinyTimber, a subset of the C language closely matching Timber’s execution model. We quantify various costs of a TinyTimber implementation of the model (such as context switching and message passing overheads) on a number of hardware platforms and compare them to the costs of the more common thread-based approach. We then demonstrate how some of these costs can be mitigated using stack resource policy. On a separate track, we present a feasibility test for garbage collection in a reactive real-time system with automatic memory management, which is a necessary component for verification of correctness of a real-time system implemented in Timber
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| 14. |
- Asadi, M., et al.
(författare)
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Accurate detection of paroxysmal atrial fibrillation with certified-GAN and neural architecture search
- 2023
-
Ingår i: Scientific Reports. - : NLM (Medline). - 2045-2322. ; 13:1
-
Tidskriftsartikel (refereegranskat)abstract
- This paper presents a novel machine learning framework for detecting PxAF, a pathological characteristic of electrocardiogram (ECG) that can lead to fatal conditions such as heart attack. To enhance the learning process, the framework involves a generative adversarial network (GAN) along with a neural architecture search (NAS) in the data preparation and classifier optimization phases. The GAN is innovatively invoked to overcome the class imbalance of the training data by producing the synthetic ECG for PxAF class in a certified manner. The effect of the certified GAN is statistically validated. Instead of using a general-purpose classifier, the NAS automatically designs a highly accurate convolutional neural network architecture customized for the PxAF classification task. Experimental results show that the accuracy of the proposed framework exhibits a high value of 99.0% which not only enhances state-of-the-art by up to 5.1%, but also improves the classification performance of the two widely-accepted baseline methods, ResNet-18, and Auto-Sklearn, by [Formula: see text] and [Formula: see text].
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| 15. |
- Asadi, Nima, et al.
(författare)
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Run-Time Monitoring of Timing Constraints : A Survey of Methods and Tools
- 2013
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Konferensbidrag (refereegranskat)abstract
- Despite the availability of static analysis methods to achieve a correct-by-construction design for different systems in terms of timing behavior, violations of timing constraints can still occur at run-time due to different reasons. The aim of monitoring of system performance with respect to the timing constraints is to detect the violations of timing specifications, or to predict them based on the current system performance data. Considerable work has been dedicated to suggesting efficient performance monitoring approaches during the past years. This paper presents a survey and classification of those approaches in order to help researchers gain a better view over different methods and developments in monitoring of timing behavior of systems. Classifications of the mentioned approaches are given based on different items that are seen as important in developing a monitoring system, i.e. the use of additional hardware, the data collection approach, etc. Moreover, a description of how these different methods work is presented in this paper along with the advantages and downsides of each of them.
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| 16. |
- Ashjaei, Seyed Mohammad Hossein, 1980-, et al.
(författare)
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A novel frame preemption model in TSN networks
- 2021
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Ingår i: Journal of systems architecture. - : Elsevier B.V.. - 1383-7621 .- 1873-6165. ; 116
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Tidskriftsartikel (refereegranskat)abstract
- This paper identifies a limitation in the frame preemption model in the TSN standard (IEEE 802.1Q-2018), due to which high priority frames can experience significantly long blocking delays, thereby exacerbating their worst-case response times. This limitation can have a considerable impact on the design, analysis and performance of TSN-based systems. To address this limitation, the paper presents a novel and more efficient frame preemption model in the TSN standard that allows over 90% reduction in the maximum blocking delay leading to lower worst-case response times of high priority frames compared to the frame preemption model used in the existing works. The paper also shows that the improvement becomes even more significant in multi-switch TSN networks. In order to evaluate the effects of preemption, the paper performs simulations by enabling and disabling preemptions as well as enabling and disabling the Hold/Release mechanism supported by TSN. Furthermore, the paper performs a comparative evaluation of the two models of frame preemption in TSN using simulations. The evaluation shows that the maximum response times of high priority frames can be significantly reduced with very small impact on the response times of lower priority frames. The paper also shows the improvement in the maximum response times of higher priority frames using an automotive industrial use case that employs a multi-hop TSN network for on-board communication.
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| 17. |
- Behnam, Moris
(författare)
-
Hierarchical Real Time Scheduling and Synchronization
- 2008
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The Hierarchical Scheduling Framework (HSF) has been introduced to enable compositional schedulability analysis and execution of embedded software systems with real-time constraints. In this thesis, we consider a system consisting of a number of semi-independent components called subsystems, and these subsystems are allowed to share logical resources. The HSF provides CPU-time to the subsystems and it guarantees that the individual subsystems respect their allocated CPU budgets. However, if subsystems are allowed to share logical resources, extra complexity with respect to analysis and run-time mechanisms is introduced. In this thesis we address three issues related to hierarchical scheduling of semi-independent subsystems. In the first part, we investigate the feasibility of implementing the hierarchical scheduling framework in a commercial operating system, and we present the detailed figures of various key properties with respect to the overhead of the implementation. In the second part, we studied the problem of supporting shared resources in a hierarchical scheduling framework and we propose two different solutions to support resource sharing. The first proposed solution is called SIRAP, a synchronization protocol for resource sharing in hierarchically scheduled open real-time systems, and the second solution is an enhanced overrun mechanism. In the third part, we present a resource efficient approach to minimize system load (i.e., the collective CPU requirements to guarantee the schedulability of hierarchically scheduled subsystems). Our work is motivated from a tradeoff between reducing resource locking times and reducing system load. We formulate an optimization problem that determines the resource locking times of each individual subsystem with the goal of minimizing the system load subject to system schedulability. We present linear complexity algorithms to find an optimal solution to the problem, and we prove their correctness
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| 18. |
- Behnam, Moris, et al.
(författare)
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Independent Abstraction and Dynamic Slack Reclaiming in Hierarchical Real-Time Open Systems
- 2007
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Ingår i: Proceedings of the Work-In-Progress (WIP) session of the 19th Euromicro Conference on Real-Time Systems (ECRTS'07), Pisa, Italy. ; , s. 1-4
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Konferensbidrag (refereegranskat)abstract
- Independent subsystem abstraction allows subsystems to be developed and validated separately and supports an easier subsystem integration. In particular, this approach is desirable in open systems, since it does not require knowledge of temporal behaviour of other subsystems. However, independentabstraction, assuming the worst-case CPU supply pattern, requires extra CPU allocations. We present our work in progress on dynamic slack reclamation, which keeps track of such extra CPU allocations at run time. We are also investigating how to utilize those extra resources for supporting soft real-time tasks.
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| 19. |
- Behnam, Moris, et al.
(författare)
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Multi-core Composability in the Face of Memory Bus Contention
- 2012
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Konferensbidrag (refereegranskat)abstract
- In this paper we describe the problem of achieving composability of independently developed real-time subsystems to be executed on a multicore platform.We evaluate existing work for achieving real-time performance on multicores and illustrate their lack with respect to composability. To better address composability we present a multi-resource server-based scheduling technique to provide predictable performance when composing multiple subsystems on a multicore platform. To achieve composability also on multicore platforms, we propose to add memory-bandwidth as an additional server resource. Tasks within our multi-resource servers are guaranteed both CPU- and memory-bandwidth; thus the performance of a server will become independent of resource usage by tasks in other servers. We are currently implementing multi-resource servers for the Enea’s OSE operating system for a P4080 8-core processor to be tested with software for a 3G-basestation.
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| 20. |
- Behnam, Moris, 1973-, et al.
(författare)
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Overrun Methods and Resource Holding Times for Hierarchical Scheduling of Semi-Independent Real-Time Systems
- 2010
-
Ingår i: IEEE Transactions on Industrial Informatics. - 1551-3203. ; 6:1, s. 93-104
-
Tidskriftsartikel (refereegranskat)abstract
- The Hierarchical Scheduling Framework (HSF) has been introduced as a design-time framework toenable compositional schedulability analysis of embedded software systems with real-time properties. Inthis paper a software system consists of a number of semi-independent components called subsystems.Subsystems are developed independently and later integrated to form a system. To support this designprocess, in the paper, the proposed methods allow non-intrusive configuration and tuning of subsystemtiming-behaviour via subsystem interfaces for selecting scheduling parameters.This paper considers three methods to handle overruns due to resource sharing between subsystemsin the HSF. For each one of these three overrun methods corresponding scheduling algorithms and associatedschedulability analysis are presented together with analysis that shows under what circumstances one or the other is preferred. The analysis is generalized to allow for both Fixed Priority Scheduling (FPS)and Earliest Deadline First (EDF) scheduling. Also, a further contribution of the paper is the techniqueof calculating resource-holding times within the framework under different scheduling algorithms; theresource holding times being an important parameter in the global schedulability analysis.
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| 21. |
- Behnam, Moris, et al.
(författare)
-
Overrun Methods for Semi-Independent Real-Time Hierarchical Scheduling
- 2009
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- The Hierarchical Scheduling Framework (HSF) has been introduced as a design-time framework to enable compositional schedulability analysis of embedded software systems with real-time properties. In this paper a software system consists of a number of semi-independent components called subsystems. Subsystems are developed independently and later integrated to form a system. To support this design process, in the paper, the proposed methods allow non-intrusive configuration and tuning of subsystem timing-behaviour via subsystem interfaces for selecting scheduling parameters. This paper considers three methods to handle overruns due to resource sharing between subsystems in the HSF. For each one of these three overrun methods corresponding scheduling algorithms The work in this paper is supported by the Swedish Foundation for Strategic Research (SSF), via the research programme PROGRESS. and associated schedulability analysis are presented together with analysis that shows under what circumstances one or the other is preferred. The analysis is generalized to allow for both Fixed Priority Scheduling (FPS) and Earliest Deadline First (EDF) scheduling. Also, a further contribution of the paper is the technique of calculating resource-holding times within the framework under different scheduling algorithms. The resource holding times being an important parameter in the global schedulability analysis.
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| 22. |
- Behnam, Moris, et al.
(författare)
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Real-Time Subsystem Integration in the Presence of Shared Resources
- 2006
-
Ingår i: Proceedings of the Work-In-Progress (WIP) session of the 27th IEEE Real-Time Systems Symposium (RTSS'06), Rio de Janeiro, Brazil.
-
Konferensbidrag (refereegranskat)abstract
- We present our ongoing work to support the difficult, time consuming, and error-prone process of subsystem integration in the real-time domain. Our work will result in methods where independently developed subsystems, including both hard real-time and soft real-time functions, can be easily integrated without resulting unpredictable timing behaviour. The methods will also facilitate subsystem reuse, since a subsystem can easily be integrated in a new environment. Related research and methods are presented, together with our ongoing work in the area.
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| 23. |
- Behnam, Moris, et al.
(författare)
-
SIRAP: A Global Resource Sharing Protocol Facilitating Integration of Semi-independent Real-Time Systems
- 2007
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- This paper presents a protocol for resource sharing in a hierarchical real-time scheduling framework. Together, the protocol and the scheduling framework significantly reduce the efforts and errors associated with integrating multiple semi-independent subsystems on a single processor. Thus, our proposed techniques facilitate modern software development processes, where subsystems are developed by independent teams (or subcontractors) and at a later stage integrated into a single product. Using our solution, a subsystem need not know, and is not dependent on, the timing behaviour of other subsystems; even though they share mutually exclusive resources. In this paper we also prove the correctness of our approach and evaluate its efficiency.
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| 24. |
- Behnam, Moris, et al.
(författare)
-
Software architecture for next generation hyperparallel cyber-physical hardware platforms : challenges and opportunities
- 2015
-
Ingår i: ECSAW '15 Proceedings of the 2015 European Conference on Software Architecture Workshops. - New York, NY, USA : ACM. - 9781450333931
-
Konferensbidrag (refereegranskat)abstract
- We present what is destined to become the de-facto standard for hardware platforms for next generation cyber-physical systems. Heterogeneous System Architecture (HSA) is an initiative to harmonize the industry around a common architecture which is easier to program and is an open standard defining the key interfaces for parallel computation. Since HSA is supported by virtually all major players in the silicon market we can conjecture that HSA, with its capabilities and quirks, will highly influence both the hardware and software for next generation cyber-physical systems. In this paper we describe HSA and discuss how its nature will influence architectures of system software and application software. Specifically, we believe that the system software needs to both leverage the hyperparallel nature of HSA while providing predictable and efficient resource allocation to different parallel activities. The application software, on the other hand, should be isolated from the complexity of the hardware architecture but yet be able to efficiently use the full potential of the hyperparallel nature of HSA.
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| 25. |
- Behnam, Moris, 1973-
(författare)
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Synchronization Protocols for a Compositional Real-Time Scheduling Framework
- 2010
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In this thesis we propose techniques to simplify the integration of subsystems while minimizing the overall amount of CPU resources needed to guarantee the schedulability of real-time tasks. In addition, we provide solutions to the problem of allowing for the use of logical resources requiring mutual exclusion.The contribution of the thesis is presented in three parts. In the first part, we propose a synchronization protocol, called SIRAP, to facilitate sharing of logical resources in a hierarchical scheduling framework. In addition, we extend an existing synchronization protocol, called HSRP, such that each subsystem can be developed independently. The performance of the proposed protocols is evaluated by extensive simulations. In the second part, we present an efficient schedulability analysis that exploits the lower scheduling overhead introduced by each of the proposed protocols. Finally, in the third part, we propose new methods and algorithms that find the optimal system parameters (e.g., optimal resource ceiling), that minimize the amount of CPU resources required to ensure schedulability, when using the proposed synchronization protocols in a hierarchical scheduling framework.The motivation of this work comes from an emerging industrial trend in embedded software systems development to integrate multiple applications (subsystems) on a small number of processors. The purpose of this integration is to reduce the hardware related costs as well as the communication complexity between processors. In this setting a large number of industrial applications face the problem of preserving their real-time properties after their integration onto a single processor. In addition, temporal isolation between the applications during runtime may be required to prevent failure propagation between different applications.Specifically, we propose a hierarchical scheduling framework that allows for a simplified integration of subsystems. The framework preserves the essential temporal characteristics of the subsystems, both when running in isolation as well as when they are integrated with other subsystems. In this thesis, we assume a model where a system consists of a number of subsystems. The subsystems can interact with each other using shared logical resources. The framework ensures that the individual subsystem respects its allocated share of the processor. The difficulty lies in allowing two or more subsystems to share logical resources, which introduces an additional complexity in the schedulability analysis and also increases the system load.
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