5,059 research outputs found
A Unifying View of Loosely Time-Triggered Architectures
Cyber-Physical Systems require distributed architectures to support safety critical real-time control. Hermann Kopetz' Time-Triggered Architecture (TTA) has been proposed as both an architecture and a comprehensive paradigm for systems architecture, for such systems. TTA offers the programmer a logical discrete time compliant with synchronous programming, together with timing bounds. A clock synchronization protocol is required, unless the local clocks used themselves provide the recquired accuracy. To relax the strict requirements on synchronization imposed by TTA, Loosely Time-Triggered Architectures (LTTA) have been proposed. In LTTA, computation and communication units are all triggered by autonomous, unsynchronized, clocks. Communication media act as shared memories between writers and readers and communication is non blocking. This is at the price of communication artifacts (such as duplication or loss of data), which must be compensated for by using some "LTTA protocol". In this paper we pursue our previous work by providing a unified presentation of the two variants of LTTA (token- and time-based), with simplified analyses. We compare these two variants regarding performance and robustness and we provide ways to combine them. This report was prepared for a lecture in GeÌrard Berry's seminar series at the ColleÌge de France, March 5, 2014; it is a corrected version of a paper, which appeared at Emsoft'2010. It is dedicated to our close friend Paul Caspi who died in April 2012.Les infrastructures de calcul distribueÌes pour le controÌle des systeÌmes embarqueÌs critiques requieÌrent des proprieÌteÌs particulieÌres destineÌes aÌ preÌserver les caracteÌristiques attendues du controÌleur. Les architectures TTA (Time-Triggered Architectures) ont eÌteÌ proposeÌes par Hermann Kopetz, aÌ la fois comme une architecture de calcul et comme une meÌthodologie de conception des systeÌmes. TTA offre au programmeur un temps logique conforme aÌ celui de la programmation synchrone, avec en outre un controÌle strict du temps. Il requiert un protocole de synchronisation entre les horloges du systeÌme reÌparti. Pour affaiblir ces hypotheÌses, les architectures LTTA (Loosely Time-Triggered Architectures) ont eÌteÌ proposeÌes reÌcemment. Dans LTTA, les calculs et les communications sont rythmeÌes par des horloges locales, non synchroniseÌes. Les supports de communication se comportent comme des meÌmoires partageÌes. La communication est donc non-bloquante. Ce type de communiccation creÌe eÌvidemment des artefacts aÌ combattre par un protocole dit "LTTA". Dans cet article nous preÌsentons une approche unifieÌe des deux techniques connues pour ce type de protocole, reposant sur l'usage, soit de jetons, soit du temps. On compare ces deux variantes et on eÌtudie leur performance. Le preÌsent rapport est une version corrigeÌe d'un article paru aÌ Emsoft'2010. Il est deÌdieÌ aÌ notre treÌs cher ami Paul Caspi, deÌceÌdeÌ en Avril 2012
Parallelizing RRT on distributed-memory architectures
This paper addresses the problem of improving the performance of the Rapidly-exploring Random Tree (RRT) algorithm by parallelizing it. For scalability reasons we do so on a distributed-memory architecture, using the message-passing paradigm. We present three parallel versions of RRT along with the technicalities involved in their implementation. We also evaluate the algorithms and study how they behave on different motion planning problems
Parallelizing RRT on large-scale distributed-memory architectures
This paper addresses the problem of parallelizing the Rapidly-exploring Random Tree (RRT) algorithm on large-scale distributed-memory architectures, using the Message Passing Interface. We compare three parallel versions of RRT based on classical parallelization schemes. We evaluate them on different motion planning problems and analyze the various factors influencing their performance
A Unifying View of Loosely Time-Triggered Architectures
Cyber-Physical Systems require distributed architectures to support safety critical real-time control. Hermann Kopetz' Time-Triggered Architecture (TTA) has been proposed as both an architecture and a comprehensive paradigm for systems architecture, for such systems. TTA offers the programmer a logical discrete time compliant with synchronous programming, together with timing bounds. A clock synchronization protocol is required, unless the local clocks used themselves provide the recquired accuracy. To relax the strict requirements on synchronization imposed by TTA, Loosely Time-Triggered Architectures (LTTA) have been proposed. In LTTA, computation and communication units are all triggered by autonomous, unsynchronized, clocks. Communication media act as shared memories between writers and readers and communication is non blocking. This is at the price of communication artifacts (such as duplication or loss of data), which must be compensated for by using some "LTTA protocol". In this paper we pursue our previous work by providing a unified presentation of the two variants of LTTA (token- and time-based), with simplified analyses. We compare these two variants regarding performance and robustness and we provide ways to combine them. This report was prepared for a lecture in GeÌrard Berry's seminar series at the ColleÌge de France, March 5, 2014; it is a corrected version of a paper, which appeared at Emsoft'2010. It is dedicated to our close friend Paul Caspi who died in April 2012.Les infrastructures de calcul distribueÌes pour le controÌle des systeÌmes embarqueÌs critiques requieÌrent des proprieÌteÌs particulieÌres destineÌes aÌ preÌserver les caracteÌristiques attendues du controÌleur. Les architectures TTA (Time-Triggered Architectures) ont eÌteÌ proposeÌes par Hermann Kopetz, aÌ la fois comme une architecture de calcul et comme une meÌthodologie de conception des systeÌmes. TTA offre au programmeur un temps logique conforme aÌ celui de la programmation synchrone, avec en outre un controÌle strict du temps. Il requiert un protocole de synchronisation entre les horloges du systeÌme reÌparti. Pour affaiblir ces hypotheÌses, les architectures LTTA (Loosely Time-Triggered Architectures) ont eÌteÌ proposeÌes reÌcemment. Dans LTTA, les calculs et les communications sont rythmeÌes par des horloges locales, non synchroniseÌes. Les supports de communication se comportent comme des meÌmoires partageÌes. La communication est donc non-bloquante. Ce type de communiccation creÌe eÌvidemment des artefacts aÌ combattre par un protocole dit "LTTA". Dans cet article nous preÌsentons une approche unifieÌe des deux techniques connues pour ce type de protocole, reposant sur l'usage, soit de jetons, soit du temps. On compare ces deux variantes et on eÌtudie leur performance. Le preÌsent rapport est une version corrigeÌe d'un article paru aÌ Emsoft'2010. Il est deÌdieÌ aÌ notre treÌs cher ami Paul Caspi, deÌceÌdeÌ en Avril 2012
The SIGNAL Approach to the Design of System Architectures
International audienceModeling plays a central role in system engineering. It significantly reduces costs and efforts in the design by providing developers with means for cheaper and more relevant experimentations. So, design choices can be assessed earlier. The use of a formalism, such as the synchronous language SIGNAL which relies on solid mathematical foundations for the modeling, allows validation. This is the aim of the methodology defined for the design of embedded systems where emphasis is put on formal techniques for verification, analysis, and code generation. This paper mainly focuses on the modeling of architecture components using SIGNAL. For illustration, we consider the modeling of a bounded FIFO queue, which is intended to be used for communication protocols. We bring out the capabilities of SIGNAL to allow specifications in an elegant way, and we check few elementary properties on the resulting model for correctness
Scaling up classification rule induction through parallel processing
The fast increase in the size and number of databases demands data mining approaches that are scalable to large amounts of data. This has led to the exploration of parallel computing technologies in order to perform data mining tasks concurrently using several processors. Parallelization seems to be a natural and cost-effective way to scale up data mining technologies. One of the most important of these data mining technologies is the classification of newly recorded data. This paper surveys advances in parallelization in the field of classification rule induction
MGSim - Simulation tools for multi-core processor architectures
MGSim is an open source discrete event simulator for on-chip hardware
components, developed at the University of Amsterdam. It is intended to be a
research and teaching vehicle to study the fine-grained hardware/software
interactions on many-core and hardware multithreaded processors. It includes
support for core models with different instruction sets, a configurable
multi-core interconnect, multiple configurable cache and memory models, a
dedicated I/O subsystem, and comprehensive monitoring and interaction
facilities. The default model configuration shipped with MGSim implements
Microgrids, a many-core architecture with hardware concurrency management.
MGSim is furthermore written mostly in C++ and uses object classes to represent
chip components. It is optimized for architecture models that can be described
as process networks.Comment: 33 pages, 22 figures, 4 listings, 2 table
COIN: Opening the internet of things to people's mobile devices
People's interaction with IoT devices such as proximity beacons, body-worn sensors, and controllable light bulbs is often mediated through personal mobile devices. Current approaches usually make applications operate in separate silos, as the functionality of IoT devices is fixed by vendors and typically accessed only through low-level proprietary APIs. This limits the flexibility in designing applications and requires intense wireless interactions, which may impact energy consumption. COIN is a system architecture that breaks this separation by allowing developers to flexibly run a slice of a mobile app's logic onto IoT devices. Mobile apps can dynamically deploy arbitrary tasks implemented as loosely coupled components. The underlying runtime support takes care of the coordination across tasks and of their real-time scheduling. Our prototype indicates that COIN both enables increased flexibility and improves energy efficiency at the IoT device, compared to traditional architectures
Loosely Time-Triggered Architectures: Improvements and Comparisons
International audienceLoosely Time-Triggered Architectures (LTTAs) are a proposal for constructing distributed embedded control systems. They build on the quasi-periodic architecture, where computing units execute 'almost periodically', by adding a thin layer of middleware that facilitates the implementation of synchronous applications.In this paper, we show how the deployment of a synchronous application on a quasi-periodic architecture can be modeled using a synchronous formalism. Then we detail two protocols, Back-Pressure LTTA, reminiscent of elastic circuits, and Time-Based LTTA, based on waiting. Compared to previous work, we present controller models that can be compiled for execution and a simplified version of the Time-Based protocol. We also compare the LTTA approach with architectures based on clock synchronization
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