The Experts below are selected from a list of 185643 Experts worldwide ranked by ideXlab platform

Knut Åkesson - One of the best experts on this subject based on the ideXlab platform.

  • on formal analysis of iec 61499 applications part b Execution semantics
    IEEE Transactions on Industrial Informatics, 2010
    Co-Authors: Goran Cengic, Knut Åkesson
    Abstract:

    IEC 61499 is a standard architecture, based on function blocks, for developing distributed control and measurement applications. However, the standard has no formal semantics and different interpretations of the standard have emerged. As a consequence, the Execution behavior of applications running on different platforms may exhibit different behavior, thus making it harder to transfer applications between the platforms. This paper shows how three different Execution semantics, buffered sequential Execution Model (BSEM), nonpreempted multithreaded (NPMTR), and cyclic buffered Execution Model (CBEM) can be mathematically defined. The mathematical definitions can be used to analyze an application's behavior when executed using those Execution semantics. The mathematical definitions have been used as a basis for implementation of a runtime environment and a software tool that generates formal Models suitable for formal verification. Formal verification can be used to help discover Execution errors before the application is executed on the factory floor.

  • Definition of the Execution Model used in the Fuber IEC 61499 runtime environment
    2008 6th IEEE International Conference on Industrial Informatics, 2008
    Co-Authors: Goran Cengic, Knut Åkesson
    Abstract:

    The buffered sequential Execution Model (BSENI) for IEC 61499 function block applications is presented. Before the Execution of the application the composite function blocks are flattened. The resulting application containing the basic and service interface function blocks is executed. The basic function blocks are put in the ready queue in the same order that they receive the input events, hence the word ldquosequentialrdquo in the name. Each basic function block keeps a queue of incoming events with their associated data, hence the word ldquobufferedrdquo in the name. Scheduling policy of the blocks is in the scheduling function while the Execution policy of the received events is in the function block instance. The extended finite automata Models suitable for formal verification of the proposed Execution Modelpsilas behavior are presented. The Model may be analyzed using a discrete event systems tool called Supremica. The presented Execution Model is implemented in the Fuber runtime environment.

  • formal Modeling of function block applications running in iec 61499 Execution runtime
    Emerging Technologies and Factory Automation, 2006
    Co-Authors: Goran Cengic, Oscar Ljungkrantz, Knut Åkesson
    Abstract:

    The Execution Model in a new standard for distributed control systems, IEC 61499, is analyzed. It is shown how the same standard compliant application running in two different standard compliant runtime environments may result in completely different behaviors. Thus, to achieve true portability of applications between multiple standard compliant runtime environments a more detailed Execution Model is necessary. In this paper a new runtime environment, Fuber, is presented along with a formal Execution Model. In this case the Execution Model is given as a set of interacting state machines which makes it straightforward to analyze the behavior of the application and runtime together using existing tools for formal verification.

Youfeng Wu - One of the best experts on this subject based on the ideXlab platform.

  • aggressive compiler optimization and parallelization with thread level speculation
    International Conference on Parallel Processing, 2003
    Co-Authors: Liling Chen, Youfeng Wu
    Abstract:

    We present a technique that exploits close collaboration between the compiler and the speculative multithreaded hardware to explore aggressive optimizations and parallelization for scalar programs. The compiler aggressively optimizes the frequently executed code in user programs by predicting an Execution path or the values of long-latency instructions. Based on the predicted hot Execution path, the compiler forms regions of greatly simplified data and control flow graphs and then performs aggressive optimizations on the formed regions. Thread level speculation (TLS) helps expose program parallelism and guarantees program correctness when the prediction is incorrect. With the collaboration of compilers and speculative multithreaded support, the program performance can be significantly improved. The preliminary results with simple trace regions demonstrate that the performance gain on dynamic compiler schedule cycles can be 33% for some benchmark and about 10%, on the average, for all the eight SpecInt95 benchmarks. For SpecInt2k, the performance gain is up to 23% with the conservative Execution Model. With a cycle accurate simulator with the conservative Execution Model, the overall performance gain by considering runtime factors (e.g., cache misses and branch misprediction) for vortex and m88ksim is 12% and 14.7%, respectively. The performance gain can be higher with more sophisticated region formation and region-based optimizations

Rajiv Gupta - One of the best experts on this subject based on the ideXlab platform.

  • copy or discard Execution Model for speculative parallelization on multicores
    International Symposium on Microarchitecture, 2008
    Co-Authors: Chen Tian, Min Feng, Vijay Nagarajan, Rajiv Gupta
    Abstract:

    The advent of multicores presents a promising opportunity for speeding up sequential programs via profile-based speculative parallelization of these programs. In this paper we present a novel solution for efficiently supporting software speculation on multicore processors. We propose the Copy or Discard (CorD) Execution Model in which the state of speculative parallel threads is maintained separately from the nonspeculative computation state. If speculation is successful, the results of the speculative computation are committed by copying them into the non-speculative state. If misspeculation is detected, no costly state recovery mechanisms are needed as the speculative state can be simply discarded. Optimizations are proposed to reduce the cost of data copying between nonspeculative and speculative state. A lightweight mechanism that maintains version numbers for non-speculative data values enables misspeculation detection. We also present an algorithm for profile-based speculative parallelization that is effective in extracting parallelism from sequential programs. Our experiments show that the combination of CorD and our speculative parallelization algorithm achieves speedups ranging from 3.7 to 7.8 on a Dell PowerEdge 1900 server with two Intel Xeon quad-core processors.

Goran Cengic - One of the best experts on this subject based on the ideXlab platform.

  • on formal analysis of iec 61499 applications part b Execution semantics
    IEEE Transactions on Industrial Informatics, 2010
    Co-Authors: Goran Cengic, Knut Åkesson
    Abstract:

    IEC 61499 is a standard architecture, based on function blocks, for developing distributed control and measurement applications. However, the standard has no formal semantics and different interpretations of the standard have emerged. As a consequence, the Execution behavior of applications running on different platforms may exhibit different behavior, thus making it harder to transfer applications between the platforms. This paper shows how three different Execution semantics, buffered sequential Execution Model (BSEM), nonpreempted multithreaded (NPMTR), and cyclic buffered Execution Model (CBEM) can be mathematically defined. The mathematical definitions can be used to analyze an application's behavior when executed using those Execution semantics. The mathematical definitions have been used as a basis for implementation of a runtime environment and a software tool that generates formal Models suitable for formal verification. Formal verification can be used to help discover Execution errors before the application is executed on the factory floor.

  • Definition of the Execution Model used in the Fuber IEC 61499 runtime environment
    2008 6th IEEE International Conference on Industrial Informatics, 2008
    Co-Authors: Goran Cengic, Knut Åkesson
    Abstract:

    The buffered sequential Execution Model (BSENI) for IEC 61499 function block applications is presented. Before the Execution of the application the composite function blocks are flattened. The resulting application containing the basic and service interface function blocks is executed. The basic function blocks are put in the ready queue in the same order that they receive the input events, hence the word ldquosequentialrdquo in the name. Each basic function block keeps a queue of incoming events with their associated data, hence the word ldquobufferedrdquo in the name. Scheduling policy of the blocks is in the scheduling function while the Execution policy of the received events is in the function block instance. The extended finite automata Models suitable for formal verification of the proposed Execution Modelpsilas behavior are presented. The Model may be analyzed using a discrete event systems tool called Supremica. The presented Execution Model is implemented in the Fuber runtime environment.

  • formal Modeling of function block applications running in iec 61499 Execution runtime
    Emerging Technologies and Factory Automation, 2006
    Co-Authors: Goran Cengic, Oscar Ljungkrantz, Knut Åkesson
    Abstract:

    The Execution Model in a new standard for distributed control systems, IEC 61499, is analyzed. It is shown how the same standard compliant application running in two different standard compliant runtime environments may result in completely different behaviors. Thus, to achieve true portability of applications between multiple standard compliant runtime environments a more detailed Execution Model is necessary. In this paper a new runtime environment, Fuber, is presented along with a formal Execution Model. In this case the Execution Model is given as a set of interacting state machines which makes it straightforward to analyze the behavior of the application and runtime together using existing tools for formal verification.

Lloyd A Treinish - One of the best experts on this subject based on the ideXlab platform.

  • an extended data flow architecture for data analysis and visualization
    IEEE Visualization, 1995
    Co-Authors: Greg Abram, Lloyd A Treinish
    Abstract:

    Modular visualization environments utilizing a data-flow Execution Model have become quite popular in recent years, especially those that incorporate visual programming tools. However, simplistic implementations of such an Execution Model are quite limited when applied to problems of realistic complexity, which negate the intuitive advantage of data-flow systems. This situation can be resolved by extending the Execution Model to incorporate a more complete and efficient programming infrastructure while still preserving the virtues of "pure data-flow". This approach has been used for the implementation of a general-purpose software package, IBM Visualization Data Explorer.