In this chapter we define what a mixed-time-criticality system is and what its requirements are. After defining the concepts that such systems should follow, we described CompSOC, which is one example of a mixed-time-criticality platform.

We describe, in detail, how multiple resources, such as processors, memories, and interconnect, are combined into a larger hardware platform, and especially how they are shared between applications using different arbitration schemes.

Following this, the software architecture that transforms the single hardware platform into multiple virtual execution platforms, one per application, is described. Skip to main content. Advertisement Hide. Living reference work entry First Online: 10 April This is a preview of subscription content, log in to check access.

Akesson B, Goossens K Architectures and modeling of predictable memory controllers for improved system integration. Akesson B, Goossens K Memory controllers for real-time embedded systems.

time-predictable and composable architectures for dependable embedded systems

Embedded systems series, 1st edn. Springer, New York Google Scholar. Bolder J, Oomen T Rational basis functions in iterative learning control — with experimental verification on a motion system. In: Proceedings of design automation conference DAC. In: Proceedings of the 44th annual design automation conference, New York. Goossens K, Hansson A The Aethereal network on chip after ten years: goals, evolution, lessons, and future.

Special issue on network-on-chip architectures and design methodologies Google Scholar. Hansson A, Goossens K Trade-offs in the configuration of a network on chip for multiple use-cases. Hansson A, Goossens K An on-chip interconnect and protocol stack for multiple communication paradigms and programming models. Embedded systems series. Kirsch C, Sokolova A The logical execution time paradigm.

Kopetz H Real-time systems: design principles for distributed embedded applications. Moreira O, Corporaal H Scheduling real-time streaming applications onto an embedded multiprocessor. Springer, Cham Google Scholar. Elsevier Google Scholar. Nelson A Composable and predictable power management. Obermaisser R, Weber D Architectures for mixed-criticality systems based on networked multi-core chips. In: Advances in design and specification languages for SoCs. J Microprocess Microsyst 39 8 — Rushby J Partitioning in avionics architectures: requirements, mechanisms, and assurance.

Trujillo S, Crespo A, Alonso A, Perez J Multipartes: multi-core partitioning and virtualization for easing the certification of mixed-criticality systems. J Microprocess Microsyst 38 8, part B — Zhang H Service disciplines for guaranteed performance service in packet-switching networks. Personalised recommendations. Cite entry How to cite?

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You can change the active elements on the page buttons and links by pressing a combination of keys:. I accept. Polski English Login or register account. Time-predictable and composable architectures for dependable embedded systems. Abstract Embedded systems must interact with their real-time environment in a timely and dependable fashion. As a result, embedded systems are often fragile in their real-time behaviour, and take longer to design and test than planned. Several techniques have been proposed to make real-time embedded systems more robust, and to ease the process of designing embedded systems: 1.

Precision-timed and time-triggered architectures, to make time a first-class citizen of system design. Deterministic architectures for repeatable timing behaviour. Composability, which guarantees that the non -functional behaviour of components is unchanged on integration in a larger system. Authors Close.

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time-predictable and composable architectures for dependable embedded systems

Yes No. Verimag, University Joseph Fourier, France. Eindhoven university of technology, Netherlands. University of Salzburg, Austria. University of Siegen, Germany.

time-predictable and composable architectures for dependable embedded systems

Keywords composability System on chip design methodology real-time determinism predictability composability System on chip design methodology real-time determinism predictability. Additional information Data set: ieee. Publisher IEEE. You have to log in to notify your friend by e-mail Login or register account. Download to disc. High contrast On Off.Authors: AkessonBenny, GoossensKees. Verification of real-time requirements in systems-on-chip becomes more complex as more applications are integrated.

Predictable and composable systems can manage the increasing complexity using formal verification and simulation. This book explains the concepts of predictability and composability and shows how to apply them to the design and analysis of a memory controller, which is a key component in any real-time system.

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Embedded Systems Free Preview. Provides an overview of trends in embedded system design that make design of real-time SoCs difficult, error-prone, and expensive Introduces the concept of predictability, which is required for formal verification of real-time systems Introduces the concept of composability, which is a divide and conquer technique that enables performance verification per application, instead of monolithic verification for all applications together see more benefits.

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Memory Controllers for Real-Time Embedded Systems

About this book Verification of real-time requirements in systems-on-chip becomes more complex as more applications are integrated. Show all. Table of contents 9 chapters Table of contents 9 chapters Introduction Pages Akesson, Benny et al.

Proposed Solution Pages Akesson, Benny et al. Resource Arbitration Pages Akesson, Benny et al. Configuration Pages Akesson, Benny et al. Related Work Pages Akesson, Benny et al. Show next xx. Recommended for you.

PAGE 1.Today's general-purpose processors are optimized for maximum throughput. Real-time systems need a processor with both a reasonable and a known worst-case execution time WCET. Features such as pipelines with instruction dependencies, caches, branch prediction, and out-of-order execution complicate WCET analysis and lead to very conservative estimates.

In this paper, we evaluate the issues of current architectures with respect to WCET analysis. Then, we propose solutions for a time-predictable computer architecture. The proposed architecture is evaluated with implementation of some features in a Java processor. The resulting processor is a good target for WCET analysis and still performs well in the average case. Standard computer architecture is driven by the following paradigm: Make the common case fast and the uncommon case correct [ 1 ].

However, this design approach leads to architectures where the worst-case execution time WCET is high and hard to predict by static analysis.

Embedded real-time system project - R&D on dependable SoC and OS : Yamasaki's Group

For real-time systems, we have to design architectures with the following paradigm: Make the worst case fast and the whole system easy to analyze. Classic enhancements in computer architectures are pipelining, instruction and data caching, dynamic branch prediction, out-of-order execution, speculative execution, and fine-grained chip multithreading. These features are increasingly harder to model for the low-level WCET analysis.

Execution history is the key to performance enhancements, and also the main issue for WCET analysis. Thus, we need techniques to manage the execution history.

Time-Predictable Computer Architecture

Pipelines should be simple, with minimum dependencies between instructions. It is agreed that caches are mandatory to bridge the gap between processor speed and memory access time.

Caches in general, and particularly data caches, are usually hard to analyze statically. Therefore, we are introducing caches that are organized to speed up execution time and provide tight WCET bounds. We propose three different caches: 1 an instruction cache for full methods, 2 a stack cache, and 3 a small, fully associative buffer for heap access. Furthermore, the integration of a program—or compiler—managed scratchpad memory can help to tighten bounds for hard-to-analyze memory access patterns.

Out-of-order execution and speculation result in processor models that are too complex for WCET analysis. We discuss that the transistors are better used onchip multiprocessors CMPs with simple in-order pipelines.

Real-time systems are naturally multithreaded and thus map well to the explicit parallelism of chip multiprocessors. We propose a multiprocessor model with one processor per thread.

Thread switching and schedulability analysis for each individual core disappears, but the access to the shared resource main memory still needs to be scheduled. We have implemented most of the proposed concepts for evaluation in a Java processor. The Java processor JOP [ 2 ] is intended for real-time and safety critical applications written in a modern object-oriented language.

It has to be noted that all concepts can also be applied to a standard RISC processor. The following list points out the key arguments for a time-predictable computer architecture. Exploration of this parallelism with simple chip multiprocessors is a valuable option. Catching up with WCET analysis of features that enhance the average-case performance is not an option for future real-time systems.

We need a sea change and should take the constructive approach by designing computer architectures where predictable timing is a first-order design factor. The implementations of some of the proposed concepts in the context of a Java processor, as described in Section 5, have been previously published in [ 34 ].Agile development is the process of continuously cycling through the whole software development process to incrementally, quickly and visibly develop a working piece of software.

In this article we argue that given a predictable architecture, agile development is very well suited to develop real-time software.

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Without a predictable architecture, one of the iterations of the development process is likely to introduce subtle timing errors in components of the software that were not touched. In an environment where software components can be composed with known effects on the timing, and the tools check timing constraints because the underlying architecture has known performance characteristics, teams of developers can make iterations through the software without breaking working components.

Agile development methods Agile development methods are established techniques to develop software projects. A key element of agile development is quick successive iterations through the software development process. Each iteration through requirements, implementation, unit testing and user testing leads to a working product that is refined in the next iteration.

Agile development methods are attractive because they are more flexible in situations where product specifications are not fixed, and where time to market is crucial. Traditional examples where agile development methods work are web applications, compilers, or mobile phone applications. In all cases, the ability to evaluate successive prototypes, and use the information gleaned to steer subsequent prototypes, is invaluable.

For example, whether the user-interface is right in the case of the web applications, or whether the right optimizations are implemented in the case of a compiler. It is essential that the prototypes that are developed in the process of an agile development method are functional prototypes.

They may have limited functionality, but the offered functionality is bug-free, and hence the product can be used for testing purposes. Real-time systems. Real-time systems come in many shapes and forms. The distinguishing characteristic of a real-time system is that, in addition to functional requirements, timing requirements must be met for the system to operate correctly.

The level at which the timing requirements are to be met differs wildly between systems; both in terms of granularity of the timing requirements and how strict the requirements are. The most precise time requirements are systems that interface directly with other hardware. For example, when reading data from a CMOS optical sensor, pixels are required to be read at a clock of, for example, 25 MHz. This means that a pixel has to be read every 40 ns. One level less precise, an audio system will process audio samples at a rate of 48 kHz — or one audio sample every Another three orders of magnitude slower, a video player will play a frame at a rate of 30 fps, or one frame every 33 ms.

The examples above are multimedia systems, and the consequences of missing a sample vary but are unlikely to be disastrous. In the case of a single missed pixel, one line in the image will be slightly distorted; a single missed audio sample will probably result in an audible click; and a single missed frame will probably cause a slight flicker on the screen.Verification of real-time requirements in systems-on-chip becomes more complex as more applications are integrated.

Predictable and composable systems can manage the increasing complexity using formal verification and simulation. This book explains the concepts of predictability and composability and shows how to apply them to the design and analysis of a memory controller, which is a key component in any real-time system. This book is generally intended for readers interested in Systems-on-Chips with real-time applications.

It is especially well-suited for readers looking to use SDRAM memories in systems with hard or firm real-time requirements. There is a strong focus on real-time concepts, such as predictability and composability, as well as a brief discussion about memory controller architectures for high-performance computing.

Readers will learn step-by-step how to go from an unpredictable SDRAM memory, offering highly variable bandwidth and latency, to a predictable and composable shared memory, providing guaranteed bandwidth and latency to isolated applications. This journey covers concepts for making memories and arbiters behave in a predictable and composable manner, as well as architecture descriptions of hardware blocks that implement the concepts.

Skip to main content Skip to table of contents. Advertisement Hide. Front Matter Pages i-xxi. Pages Proposed Solution. Resource Arbitration. Composable Resource Front-End. Related Work. Conclusions and Future Work. Back Matter Pages Provides an overview of trends in embedded system design that make design of real-time SoCs difficult, error-prone, and expensive; Introduces the concept of predictability, which is required for formal verification of real-time systems; Introduces the concept of composability, which is a divide and conquer technique that enables performance verification per application, instead of monolithic verification for all applications together; Describes a novel approach to composability, which applies to any predictable shared resource, thus widely extending the scope of composable platforms.

This is the first approach that can efficiently support SDRAM, which is an essential system component; Provides an overview of the SDRAM architecture at a level that is relevant for system designers, not memory designers, and explains why SDRAM architectures are difficult to use in real-time systems; Describes concepts, architectures, implementation and worst-case performance analysis of predictable SDRAM accesses, as well as predictable and composable memory arbitration, which can be applied to all memory types.

Buy options.A Time-predictable Stack Cache. N1 - IEEE. Personal use of this material is permitted. N2 - Real-time systems need time-predictable architectures to support static worst-case execution time WCET analysis.

time-predictable and composable architectures for dependable embedded systems

One architectural feature, the data cache, is hard to analyze when different data areas e. This sharing leads to less precise results of the cache analysis part of the WCET analysis. Splitting the data cache for different data areas enables composable data cache analysis. The WCET analysis tool can analyze the accesses to these different data areas independently. In this paper we present the design and implementation of a cache for stack allocated data.

The combination of stack cache instructions and the hardware implementation of the stack cache is a further step towards timepredictable architectures.

NoC-Based Multiprocessor Architecture for Mixed-Time-Criticality Applications

Abstract Real-time systems need time-predictable architectures to support static worst-case execution time WCET analysis. Real time systems. Bibliographical note IEEE. IEEE, U2 - Access to Document Patstack Accepted author manuscript, KB.


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