A case study in design space exploration: the Tosca environmentapplied to a telecommunication link controller

The concept of system design, or codesign, includes a variety of possible definitions according to the considered relevant aspects, the application field, and the system granularity of the analysis. The novelty of codesign with respect to the design of pure hardware and software, which are well-known subjects, arises from the tight integration between the two types of design and from the global scope of the design constraints. Since such applications strive for high volumes, there is a payoff for size, power, and speed optimization techniques. This article presents a system-level design methodology to specify, analyze, and explore different hardware/software solutions, whose benefits have been tested by redesigning a commercial device     

Performance evaluation of efficient multi-objective evolutionary algorithms for design space exploration of embedded computer systems

Multi-objective evolutionary algorithms (MOEAs) have received increasing interest in industry because they have proved to be powerful optimizers. Despite the great success achieved, however, MOEAs have also encountered many challenges in real-world applications. One of the main difficulties in applying MOEAs is the large number of fitness evaluations (objective calculations) that are often needed before an acceptable solution can be found. There are, in fact, several industrial situations in which fitness evaluations are computationally expensive and the time available is very short. In these applications efficient strategies to approximate the fitness function have to be adopted, looking for a trade-off between optimization performance and efficiency. This is the case in designing a complex embedded system, where it is necessary to define an optimal architecture in relation to certain performance indexes while respecting strict time-to-market constraints. This activity, known as design space exploration (DSE), is still a great challenge for the EDA (electronic design automation) community. One of the most important bottlenecks in the overall design flow of an embedded system is due to simulation. Simulation occurs at every phase of the design flow and is used to evaluate a system which is a candidate for implementation. In this paper we focus on system level design, proposing an extensive comparison of the state-of-the-art of MOEA approaches with an approach based on fuzzy approximation to speed up the evaluation of a candidate system configuration. The comparison is performed in a real case study: optimization of the performance and power dissipation of embedded architectures based on a Very Long Instruction Word (VLIW) microprocessor in a mobile multimedia application domain. The results of the comparison demonstrate that the fuzzy approach outperforms in terms of both performance and efficiency the state of the art in MOEA strategies applied to DSE of a parameterized embedded system.     

Efficient design space exploration for application specific systems-on-a-chip

A reduction in the time-to-market has led to widespread use of pre-designed parametric architectural solutions known as system-on-a-chip (SoC) platforms. A system designer has to configure the platform in such a way as to optimize it for the execution of a specific application. Very frequently, however, the space of possible configurations that can be mapped onto a SoC platform is huge and the computational effort needed to evaluate a single system configuration can be very costly. In this paper we propose an approach which tackles the problem of design space exploration (DSE) in both of the fronts of the reduction of the number of system configurations to be simulated and the reduction of the time required to evaluate (i.e., simulate) a system configuration. More precisely, we propose the use of Multi-objective Evolutionary Algorithms as optimization technique and Fuzzy Systems for the estimation of the performance indexes to be optimized. The proposed approach is applied on a highly parameterized SoC platform based on a parameterized VLIW processor and a parameterized memory hierarchy for the optimization of performance and power dissipation. The approach is evaluated in terms of both accuracy and efficiency and compared with several established DSE approaches. The results obtained for a set of multimedia applications show an improvement in both accuracy and exploration time.     

Interdigitation for effective design space exploration using iSIGHT

Optimization studies for nonlinear constrained problems (i.e. most complex engineering design problems) have repeatedly shown that (i) no single optimization technique performs best for all design problems, and (ii) in most cases, a mix of techniques perform better than a single technique for a given design problem. iSIGHT^TM is a generic software framework for integration, automation, and optimization of design processes that has been developed on the foundation of interdigitation: the strategy of combining multiple optimization algorithms to exploit their desirable aspects for solving complex problems. With the recent paradigm shift from traditional optimization to design space exploration for evaluating “what-if” scenarios and trade-off studies, iSIGHT has grown from an optimization software system to a complete design exploration environment, providing a suite of design exploration tools including a collection of optimization techniques, design of experiments techniques, approximation methods, and probabilistic quality engineering methods. Likewise, the interdigitation design methodology embodied in iSIGHT has grown to support the interdigitation of all design exploration tools for effective design space exploration. In this paper we present an overview of iSIGHT, past and present, of the interdigitation design methodology and its implementation for multiple design exploration tools, and of an industrial case study for which elements of this methodology have been applied. Received December 30, 2000     

A case study of CES: a distributed collaborative editing systemimplemented in Argus

Experience implementing CES, a distributed collaborative editing system, is described. CES was written in Argus, a language that was designed to support the construction of reliable distributed programs, and exhibits a number of requirements typical of distributed applications. The authors' experience illustrates numerous areas in which the support provided by Argus for meeting those requirements was quite helpful, but also identifies several areas in which the support provided by Argus was inadequate. Some of the problems arise because of the distinction in Argus (and in other systems) between locally and remotely accessible data and the mechanisms provided for implementing each. Others arise because of limitations of the mechanisms for building user-defined data types. The authors discuss the problems they encountered, including the implications for other systems. They also suggest solutions to the problems, or in some cases further research directed at finding solutions     

STATS: A framework for microprocessor and system-level design space exploration

As microprocessor-based systems grow in complexity, and the processor-memory speed gap widens further, more emphasis needs to be placed on early design space exploration in order to produce the highest performance systems with minimal schedule impact. We discuss the critical issues associated with architectural evaluation of complex microprocessor-based systems, and present a methodology for the comprehensive and semiautomatic evaluation of processor, cache hierarchy, system interconnect, and main memory architectural and technological alternatives. We discuss the implementation of the methodology, and describe how it can be used in early design space exploration. The unique aspects of the methodology are further illustrated through two architectural investigations performed using the toolset.     

Agile product line planning: A collaborative approach and a case study

Agile methods and product line engineering (PLE) have both proven successful in increasing customer satisfaction and decreasing time to market under certain conditions. Key characteristics of agile methods are lean and highly iterative development with a strong emphasis on stakeholder involvement. PLE leverages reuse through systematic approaches such as variability modeling or product derivation. Integrating agile approaches with product line engineering is an interesting proposition which – not surprisingly – entails several challenges: Product lines (PL) rely on complex plans and models to ensure their long-term evolution while agile methods emphasize simplicity and short-term value-creation for customers. When incorporating agility in product line engineering, it is thus essential to define carefully how agile principles can support particular PLE processes. For instance, the processes of defining and setting up a product line (domain engineering) and deriving products (application engineering) differ significantly in practices and focus with implications on the suitability of agile principles. This paper presents practical experiences of adopting agile principles in product line planning (a domain engineering activity). ThinkLets, i.e., collaborative practices from the area of collaboration engineering, are the building blocks of the presented approach as they codify agile principles such as stakeholder involvement, rapid feedback, or value-based prioritization. We discuss how our approach balances agility and the intrinsic needs of product line planning. A case study carried out with an industrial partner indicates that the approach is practicable, usable, and useful.     

Hybrid meta-model-based design space exploration method for expensive problems

Structural and Multidisciplinary Optimization - Multiple meta-models used together in the search process at least can offer an insurance against the poorly fitted meta-models and can improve...     

Maintenance-oriented design and development: a case study

Maintenance efforts are the most time and resource consuming of the entire software development process. The authors propose a different point of view that shifts the traditional perspective and thinks of the implementation stage as maintenance as well. They present a case study of the development of educational video games for children to determine the proposed method's benefits and drawbacks in this domain.     

Development of intelligent design associates: a case study

A number of human factors data sets provides guidelines and recommendations for the system design process. Much of this information is available to the human factors engineer in design handbooks, textbooks, and periodicals. While human factors design information is both available and abundant, it is not necessarily readily accessible or in a format that is easily assimilated into a particular design scenario. This paper discusses the feasibility of incorporating human factors design data into intelligent, knowledge-based systems referred to as design associates. Successful implementation of any design associate is dependent upon two key issues: conversion of human factors data into a valid knowledge base, and overcoming the knowledge representation constraints imposed by an intelligent software tool. Detailed results of a recent effort to address these issues, and subsequently implement a design associate on a commercially available intelligent software tool, are presented. This particular associate, implemented in a rule-based tool environment, aids in the selection of visual display technologies.     

Integration of humanoid robots in collaborative working environment: a case study on motion generation

This paper illustrates through a practical example an integration of a humanoid robotic architecture, with an open-platform collaborative working environment called BSCW (Be Smart-Cooperate Worldwide). BSCW is primarily designed to advocate a futuristic shared workspace system for humans. We exemplify how a complex robotic system (such as a humanoid robot) can be integrated as a proactive collaborative agent which provides services and interacts with other agents sharing the same collaborative environment workspace. Indeed, the robot is seen as a ‘user’ of the BSCW which is able to handle simple tasks and reports on their achievement status. We emphasis on the importance of using standard software such as CORBA (Common Object Request Broker Architecture) in order to easily build interfaces between several interacting complex software layers, namely from real-time constraints up to basic Internet data exchange.     

Representing situation awareness in collaborative systems: a case study in the energy distribution domain

The concept of distributed situation awareness (DSA) is currently receiving increasing attention from the human factors community. This article investigates DSA in a collaborative real-world industrial setting by discussing the results derived from a recent naturalistic study undertaken within the UK energy distribution domain. The results describe the DSA-related information used by the networks of agents involved in the scenarios analysed, the sharing of this information between the agents and the salience of different information elements used. Thus, the structure, quality and content of each network's DSA is discussed, along with the implications for DSA theory. The findings reinforce the notion that when viewing situation awareness (SA) in collaborative systems, it is useful to focus on the coordinated behaviour of the system itself, rather than on the individual as the unit of analysis and suggest that the findings from such assessments can potentially be used to inform system, procedure and training design. SA is a critical commodity for teams working in industrial systems and systems, procedures and training programmes should be designed to facilitate efficient system SA acquisition and maintenance. This article presents approaches for describing and understanding SA during real-world collaborative tasks, the outputs from which can potentially be used to inform system, training programmes and procedure design.     

A networks-on-chip architecture design space exploration – The LIB

Many on-chip network circuit and architecture techniques are incompatible with modern design flows, making them unsuitable for use in systems-on-chip. This paper presents a networks-on-chip (NoC) architecture design space exploration method for multi-processor systems-on-chip architecture. The NoC architecture design space is designed with a Layer-Interactive-Building block (LIB) methodology that is divided into three layers: application layer, link/network layer, and physical layer. The suggested LIB design paradigmatic philosophy provides modular building block structure in both hardware and software and the protocols for their interconnection in the three architecture layers. Using LIB the designer can easily select these building blocks to build application-specific NoCs to meet different application requirements such as media, graphic, software radio and communication network applications. The LIB provides the NoC building blocks, architecture interacting systems-on-chip components, the programming models and application mapping strategies. The LIB can be used as a complementary library and tools for future on-chip interconnection network design.     

Design of graph-based evolutionary algorithms: a case study for chemical process networks

This paper describes the adaptation of evolutionary algorithms (EAs) to the structural optimization of chemical engineering plants, using rigorous process simulation combined with realistic costing procedures to calculate target function values. To represent chemical engineering plants, a network representation with typed vertices and variable structure will be introduced. For this representation, we introduce a technique on how to create problem specific search operators and apply them in stochastic optimization procedures. The applicability of the approach is demonstrated by a reference example. The design of the algorithms will be oriented at the systematic framework of metric-based evolutionary algorithms (MBEAs). MBEAs are a special class of evolutionary algorithms, fulfilling certain guidelines for the design of search operators, whose benefits have been proven in theory and practice. MBEAs rely upon a suitable definition of a metric on the search space. The definition of a metric for the graph representation will be one of the main issues discussed in this paper. Although this article deals with the problem domain of chemical plant optimization, the algorithmic design can be easily transferred to similar network optimization problems. A useful distance measure for variable dimensionality search spaces is suggested.     

A GA-based design space exploration framework for parameterized system-on-a-chip platforms

The constant increase in levels of integration and reduction in the time-to-market has led to the definition of new methodologies, which lay emphasis on reuse. One emerging approach in this context is platform-based design. The basic idea is to avoid designing a chip from scratch. Some portions of the chip's architecture are predefined for a specific type of application. This implies that the basic micro-architecture of the implementation is essentially "fixed," i.e., the principal components should remain the same within a certain degree of parameterization. Many researchers predict that platforms will take the lion's share of the integrated circuit market. In this paper, we propose an approach based on genetic algorithms for exploring the design space of parameterized system-on-a-chip (SOC) platforms. Our strategy focuses on exploration of the architectural parameters of the processor, memory subsystem and bus, making up the hardware kernel of a parameterized SOC platform for the design of embedded systems with strict power consumption and performance constraints. The approach has been validated on two different parameterized architectures: one based on a RISC processor and another based on a parameterized very long instruction word architecture. The results obtained on a suite of benchmarks for embedded applications are discussed in terms of both accuracy and efficiency. As far as accuracy is concerned, the approach gives solutions uniformly distributed in a region less than 1% from the Pareto-optimal front. As regards efficiency, the exploration times required by the approach are up to 20 times shorter than those required by one of the most efficient and widely referenced approaches in the literature.     

Guided architecture trade space exploration: fusing model-based engineering and design by shopping

Software and Systems Modeling - Advances in model-based system engineering have greatly increased the predictive power of models and the analyses that can be run on them. At the same time, designs...