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70
Symbolic Model Checking of Process Networks Using Interval Diagram Techniques
, 1998
"... In this paper, an approach to symbolic model checking of process networks is introduced. It is based on interval decision diagrams (IDDs), a representation of multivalued functions. Compared to other model checking strategies, IDDs show some important properties that enable the verification of pro ..."
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Cited by 21 (9 self)
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In this paper, an approach to symbolic model checking of process networks is introduced. It is based on interval decision diagrams (IDDs), a representation of multivalued functions. Compared to other model checking strategies, IDDs show some important properties that enable the verification of process networks more adequately than with conventional approaches. Additionally, applications concerning scheduling will be shown. A new form of transition relation representation called interval mapping diagrams (IMDs)and their less general version predicate action diagrams (PADs)is explained together with the corresponding methods. 1 Introduction Process network modelsconsisting in general of concurrent processes communicating through unidirectional FIFO queuesas that of Kahn [7, 8] are commonly used, e.g., for specification and synthesis of distributed systems. They form the basis for applications such as realtime scheduling and allocation. Many other models of computation, ...
PSL: A semantic domain for flow models
 In Software and Systems Modeling
, 2005
"... Regular paper Flow models underlie popular programming languages and many graphical behavior specification tools. However, their semantics is typically ambiguous, causing miscommunication between modelers and unexpected implementation results. This article introduces a way to disambiguate common flo ..."
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Cited by 21 (2 self)
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Regular paper Flow models underlie popular programming languages and many graphical behavior specification tools. However, their semantics is typically ambiguous, causing miscommunication between modelers and unexpected implementation results. This article introduces a way to disambiguate common flow modeling constructs, by expressing their semantics as constraints on runtime sequences of behavior execution. It also shows that reduced ambiguity enables more powerful modeling abstractions, such as partial behavior specifications. The runtime representation considered in this paper uses the Process Specification Language (PSL), which is defined in firstorder logic, making it amenable to automated reasoning. The activity diagrams of the Unified Modeling Language are used for example flow models.
A Hierarchical Multiprocessor Scheduling Framework For Synchronous Dataflow Graphs
 Laboratory, University of California at Berkeley
, 1995
"... This paper discusses a hierarchical scheduling framework to reduce the complexity of scheduling synchronous dataflow (SDF) graphs onto multiple processors. The core of this framework is a clustering algorithm that reduces the number of nodes before expanding the SDF graph into a precedence DAG (dire ..."
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Cited by 21 (7 self)
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This paper discusses a hierarchical scheduling framework to reduce the complexity of scheduling synchronous dataflow (SDF) graphs onto multiple processors. The core of this framework is a clustering algorithm that reduces the number of nodes before expanding the SDF graph into a precedence DAG (directed acyclic graph). The internals of the clusters are then scheduled with uniprocessor SDF schedulers which can optimize for memory usage. The clustering is done in such a manner as to leave ample parallelism exposed for the multiprocessor scheduler. The advantages of this framework are demonstrated with several practical, realtime examples.
A ScenarioAware Data Flow Model for Combined LongRun Average and WorstCase Performance Analysis
 Proceedings of MEMOCODE, pp 185194
, 2006
"... Data flow models are used for specifying and analysing signal processing and streaming applications. However, traditional data flow models are either not capable of expressing the dynamic aspects of modern streaming applications or they do not support relevant analysis techniques. The dynamism in mo ..."
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Cited by 20 (11 self)
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Data flow models are used for specifying and analysing signal processing and streaming applications. However, traditional data flow models are either not capable of expressing the dynamic aspects of modern streaming applications or they do not support relevant analysis techniques. The dynamism in modern streaming applications often originates from different modes of operation (scenarios) in which data production and consumption rates and/or execution times may differ. This paper introduces a scenarioaware generalisation of the Synchronous Data Flow model, which uses a stochastic approach to model the order in which scenarios occur. The formally defined operational semantics of a ScenarioAware Data Flow model implies a Markov chain, which can be analysed for both longrun average and worstcase performance metrics using existing exhaustive or simulationbased techniques. The potential of using ScenarioAware Data Flow models for performance analysis of modern streaming applications is illustrated with an MPEG4 decoder example. 1.
Heterogenous Simulation  mixing discreteevent model with dataflow
, 1996
"... This paper relates to systemlevel design of signal processing systems, which are often heterogeneous in implementation technologies and design styles. The heterogeneous approach, by combining small, specialized models of computation, achieves generality and also lends itself to automatic synthesis ..."
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Cited by 17 (4 self)
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This paper relates to systemlevel design of signal processing systems, which are often heterogeneous in implementation technologies and design styles. The heterogeneous approach, by combining small, specialized models of computation, achieves generality and also lends itself to automatic synthesis and formal verification. Key to the heterogeneous approach is to define interaction semantics that resolve the ambiguities when different models of computation are brought together. For this purpose, we introduce a tagged signal model as a formal framework within which the models of computation can be precisely described and unambiguously differentiated, and their interactions can be understood. In this paper, we will focus on the interaction between dataflow models, which have partially ordered events, and discreteevent models, with their notion of time that usually defines a total order of events. A variety of interaction semantics, mainly in handling the different notions of time in the two models, are explored to illustrate the subtleties involved. An implementation based on the Ptolemy system from U.C. Berkeley is described and critiqued.
Effective heterogeneous design and cosimulation
 In NATO Advanced Study Institute Workshop on Hardware/Software Codesign
, 1995
"... ..."
On Retiming of Multirate DSP Algorithms
 In Proceedings of the IEEE International Conference on Acoustics, Speech and Signal Processing
, 1996
"... In the paper retiming of DSP algorithms exhibiting multirate behavior is treated. Using the nonordinary marked graph model and the reachability theory, we provide a new condition for valid retiming of multirate graphs. We show that for a graph with n nodes the reachability condition can be split in ..."
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Cited by 14 (3 self)
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In the paper retiming of DSP algorithms exhibiting multirate behavior is treated. Using the nonordinary marked graph model and the reachability theory, we provide a new condition for valid retiming of multirate graphs. We show that for a graph with n nodes the reachability condition can be split into the reachability condition for the topologically equivalent unitrate graph (all rates set to one), and (n 2 \Gamma n)=2 ratedependent conditions. Using this property a class of equivalent graphs of reduced complexity is introduced which are equivalent in terms of retiming. Additionally, the circuitbased necessary condition for valid retiming of multirate graphs is extended for the sufficient part. 1. INTRODUCTION Retiming was introduced as a technique to optimize hardware circuits by redistributing registers without affecting functionality [1]. Retiming is also useful for DSP software design. It changes precedence constraints among instructions or tasks, and can improve singlepro...
Realtime Signal Processing  Dataflow, Visual, and Functional Programming
, 1995
"... This thesis presents and justifies a framework for programming realtime signal processing systems. The framework extends the existing "blockdiagram" programming model; it has three components: a very highlevel textual language, a visual language, and the dataflow process network model of computat ..."
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Cited by 13 (1 self)
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This thesis presents and justifies a framework for programming realtime signal processing systems. The framework extends the existing "blockdiagram" programming model; it has three components: a very highlevel textual language, a visual language, and the dataflow process network model of computation. The dataflow process network model, although widelyused, lacks a formal description, and I provide a semantics for it. The formal work leads into a new form of actor. Having established the semantics of dataflow processes, the functional language Haskell is layered above this model, providing powerful featuresnotably polymorphism, higherorder functions, and algebraic program transformationabsent in blockdiagram systems. A visual equivalent notation for Haskell, Visual Haskell, ensures that this power does not exclude the "intuitive" appeal of visual interfaces; with some intelligent layout and suggestive icons, a Visual Haskell program can be made to look very like a block dia...
Language and Compiler Support for Stream Programs
, 2009
"... Stream programs represent an important class of highperformance computations. Defined by their regular processing of sequences of data, stream programs appear most commonly in the context of audio, video, and digital signal processing, though also in networking, encryption, and other areas. Stream ..."
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Cited by 12 (2 self)
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Stream programs represent an important class of highperformance computations. Defined by their regular processing of sequences of data, stream programs appear most commonly in the context of audio, video, and digital signal processing, though also in networking, encryption, and other areas. Stream programs can be naturally represented as a graph of independent actors that communicate explicitly over data channels. In this work we focus on programs where the input and output rates of actors are known at compile time, enabling aggressive transformations by the compiler; this model is known as synchronous dataflow. We develop a new programming language, StreamIt, that empowers both programmers and compiler writers to leverage the unique properties of the streaming domain. StreamIt offers several new abstractions, including hierarchical singleinput singleoutput streams, composable primitives for data reordering, and a mechanism called teleport messaging that enables precise event handling
Rate Derivation and Its Applications to Reactive, Realtime Embedded Systems
 In Proc. the 35th Design Automation Conf
, 1998
"... An embedded system #the system# continuously interacts with its environment under strict timing constraints, called the external constraints, and it is important to knowhow these external constraints translate to time budgets, called the internal constraints, on the tasks of the system. Knowing the ..."
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Cited by 11 (7 self)
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An embedded system #the system# continuously interacts with its environment under strict timing constraints, called the external constraints, and it is important to knowhow these external constraints translate to time budgets, called the internal constraints, on the tasks of the system. Knowing these time budgets reduces the complexity of the system 's design and validation problem and helps the designers have a simultaneous control on the system's functional as well as temporal correctness from the beginning of the design #ow. The translation is carried out by #rst deriving the rate of each task in the system, hence the term #rate derivation", using the system's task structure and the rates of the input stimuli coming into the system from its environment. The derived task rates are later used to derive and validate the rest of the internal as well as external constraints. This paper proposes a general task graph model to represent the system's task structure, techniques for deriving ...