Synthesis from specifications : basic concepts

The need has evolved for a synthesis tool at the computer system level. SpecSyn is one such tool. Basically, it will view the world as a set of chips communicating via protocols. Thus, an abstract specification would get synthesized into a set of one or more interconnected chips. From that point, detail is added to each chip's specification until its structure is synthesized or it is determined that a prefabricated chip similar in functionality can be used.Features of such a tool include executable specifications from which to synthesize, constraint driven partitioning of the specifications into components (chips) and synthesis of interfaces between them, translation into VHDL and synthesis into VHDL structures of micro-architectural components, and the use of other tools (e.g. MILO, a micro-architecture and logic optimizer, and LES, a layout expert system) to evaluate the quality of the chip layout generated from VHDL description.A major component of SpecSyn is SpecCharts, a high level specification language amenable to system level synthesis, able to represent designs from system to register transfer levels. The language consists of a hierarchy of states, represented in combined graphical and textual form, at the same time catering to the expression of concurrent behavior and specification of constraints. With it we have specified several Intel chips as well as higher level systems, and have found it to be quite powerful and easy to use.SpecSyn will have a graphical interface, from which the user can at any time view or edit a SpecChart, translate to VHDL and simulate, view statistics provided by estimators (such as area, speed, and pins), store and retrieve SpecCharts, apply basic Spec Chart operations, as well as apply the partitioning algorithms or interface synthesizer. Providing access to a wide range of tools, having a single language represent the design throughout the synthesis process, and having user specified constraints allow the user to have varying amounts of control over the synthesis process

A Survey of Process Migration Mechanisms

We define process migration as the transfer of a sufficient amount of a process's state from one machine to another for the process to execute on the target machine. This paper surveys proposed and implemented mechanisms for process migration. We pay particular attention to the designer's goals, such as performance, load-balancing, and reliability. The effect of operating system design upon the ease of implementation is discussed in some detail; we conclude that message-passing systems simplify designs for migration

The role of the host in a cooperating mainframe and workstation environment, volumes 1 and 2

In recent years, advancements made in computer systems have prompted a move from centralized computing based on timesharing a large mainframe computer to distributed computing based on a connected set of engineering workstations. A major factor in this advancement is the increased performance and lower cost of engineering workstations. The shift to distributed computing from centralized computing has led to challenges associated with the residency of application programs within the system. In a combined system of multiple engineering workstations attached to a mainframe host, the question arises as to how does a system designer assign applications between the larger mainframe host and the smaller, yet powerful, workstation. The concepts related to real time data processing are analyzed and systems are displayed which use a host mainframe and a number of engineering workstations interconnected by a local area network. In most cases, distributed systems can be classified as having a single function or multiple functions and as executing programs in real time or nonreal time. In a system of multiple computers, the degree of autonomy of the computers is important; a system with one master control computer generally differs in reliability, performance, and complexity from a system in which all computers share the control. This research is concerned with generating general criteria principles for software residency decisions (host or workstation) for a diverse yet coupled group of users (the clustered workstations) which may need the use of a shared resource (the mainframe) to perform their functions

Efficient processor management strategies for multicomputer systems

Multicomputers are cost-effective alternatives to the conventional supercomputers. Contemporary processor management schemes tend to underutilize the processors and leave many of the processors in the system idle while jobs are waiting for execution;Instead of designing faster processors or interconnection networks, a substantial performance improvement can be obtained by implementing better processor management strategies. This dissertation studies the performance issues related to the processor management schemes and proposes several ways to enhance the multicomputer systems by means of processor management. The proposed schemes incorporate the concepts of size-reduction, non-contiguous allocation, as well as job migration. Job scheduling using a bypass-queue is also studied. All the proposed schemes are proven effective in improving the system performance via extensive simulations. Each proposed scheme has different implementation cost and constraints. In order to take advantage of these schemes, judicious selection of system parameters is important and is discussed

Effective interprocess communication (IPC) in a real-time transputer network

The thesis describes the design and implementation of an interprocess communication (IPC) mechanism within a real-time distributed operating system kernel (RT-DOS) which is designed for a transputer-based network. The requirements of real-time operating systems are examined and existing design and implementation strategies are described. Particular attention is paid to one of the object-oriented techniques although it is concluded that these techniques are not feasible for the chosen implementation platform. Studies of a number of existing operating systems are reported. The choices for various aspects of operating system design and their influence on the IPC mechanism to be used are elucidated. The actual design choices are related to the real-time requirements and the implementation that has been adopted is described. [Continues.

State of the art survey of network operating systems development

The results of the State-of-the-Art Survey of Network Operating Systems (NOS) performed for Goddard Space Flight Center are presented. NOS functional characteristics are presented in terms of user communication data migration, job migration, network control, and common functional categories. Products (current or future) as well as research and prototyping efforts are summarized. The NOS products which are revelant to the space station and its activities are evaluated

Secure Virtualization and Multicore Platforms State-of-the-Art report

SVaM

Alternative strategies for asynchronous migration-controlled schemes in parallel genetic algorithm

Migration of individuals allows a fruitful interaction between subpopulations in the island model, a well known distributed approach for evolutionary computing, where separate subpopulations evolve in parallel. This model is well suited for a distributed environment running a Single Program Multiple Data (SPMD) scheme. Here, the same Genetic Algorithm (GA) is replicated in many processors and attempting better convergence, through an expected improvement on genetic diversity, selected individuals are exchanged periodically. For exchanging, an individual is selected from a source subpopulation and then exported towards a target subpopulation. Usually, the imported string is accepted on arrival and then inserted into the target subpopulation. Our earlier experiments on controlled migration showed an improvement on results when contrasted against those obtained by conventional migration approaches. This paper describes extended implementations of alternative strategies to oversee migration in asynchronous schemes for an island model and enlarges a previous work on three processors with a set of softer testing functions [9]. All of them try to decrease the risk of premature convergence. A first strategy attempts to prevent unbalanced p ropagation of genotypes by applying an acceptance threshold parameter to each incoming string. A second one permits independent evolution of subpopulations and acts only when a possible stagnation is detected. In such condition an attempt to evade falling towards a local optimum is done by inserting an expected d issimilar individual to improve genetic diversity. A third alternative strategy combines both previous mentioned strategies. The results presented are those obtained on the functions that showed to be more difficult for the island model using a replication of a simple GA. A description of the corresponding system architecture supporting the PGA implementation is described and results for the parallel distributed approach among 3, 6 and 12 processors is discussed.Facultad de Informátic

Process Driven Software Engineering Environments

Software development organizations have begun using Software Engineering Environments (SEEs) with the goal of enhancing the productivity of software developers and improving the quality of software products. The encompassing nature of a SEE means that it is typically very tightly coupled with the way an organization does business. To be most effective, the components of a SEE must be well integrated and the SEE itself must be integrated with the organization. The challenge of tool integration increases considerably when the components of the environment come from different vendors and support varying degrees of “openness”. The challenge of integration with the organization increases in a like manner when the environment must support a variety of different organizations over a long period of time. In addition to these pressures, any SEE must perform well and must “scale” well as the size of the organization changes. This paper proposes basing the Software Engineering Environment on the software development process used in an organization in order to meet the challenges of integration, performance, and scaling. The goals and services of distributed operating systems and Software Engineering Environments are outlined in order to more clearly define their roles. The motivation for using a well defined software development process is established along with the benefits of basing the Software Engineering Environment on the software development process. Components of a SEE that could effectively support the process and provide integration, performance, and scaling benefits are introduced along with an outline of an Ada program used to model the proposed components. The conclusion provides strong support for process driven SEEs, encourages the expansion of the concept into other “environments,” and cautions against literal interpretations of “process integration” that may slow the acceptance of this powerful approach