Showing papers on "Shared resource published in 1995"

System and method for providing opportunistic file access in a network environment

Abstract: A file allocation and management system for a multi-user network environment is disclosed. At least one server and two or more clients are disposed along the network in communicating via a request/response transfer protocol. Files directed for shared usage among the clients along the network are stored at the server. Each client is adapted to communicate with the server through a plurality of identifier sockets, wherein a first identifier socket is configured for bi-directional communication and a second identifier socket is configured for uni-directional communications initiated by the server. Files normally stored at the server, under appropriate circumstances may be temporarily stored in an internal cache or other memory at each client location, when the file is in use.

Workstation-implemented data storage re-routing for server fault-tolerance on computer networks

Abstract: Server fault tolerance on local area computer networks is provided by novel workstation implemented software which detects failure of a primary file server and reroutes data storage activity routed via the primary file server, to be routed via an invention-provided secondary file server. Shared file management of multiple file servers or intelligent hosts supporting a single or common high availability data storage system, for example a RAID drive, enables server or host fault tolerance to be provided for such a single highly, reliable data-storage system. Cross-mirroring in such a multi-host, high availability data storage system, along with secondary write suppression, enables server fault tolerance to be provided without significant redundant hardware costs and without a single point of failure in the data storage access paths.

Modular real-time resource management in the Rialto operating system

Abstract: This paper describes ongoing investigations into algorithms for modular distributed real-time resource management. These investigations are being conducted in the context of the Rialto operating system-an object-based real-time kernel and programming environment currently being developed within Microsoft Research. Some of the goals of this research include developing appropriate real-time programming abstractions to allow multiple independent real-time programs to dynamically coexist and share resources on the same hardware platforms. Use of these abstractions is intended both to allow individual applications to reason about their own resource requirements and for per-machine system resource planner applications to reason about and control resource allocations between potentially competing applications. The set of resources being managed is dynamically extensible, and may include remote resources in distributed environments. The local planner conducts resource negotiations with individual applications on behalf of the user, with the goal of maximizing the user's perceived utility of the set of running applications with respect to resource allocations for those applications.

SPIN—an extensible microkernel for application-specific operating system services

Abstract: Application domains such as multimedia, databases, and parallel computing, require operating system services with high performance and high functionality. Existing operating systems provide fixed interfaces and implementations to system services and resources. This makes them inappropriate for applications whose resource demands and usage patterns are poorly matched by the services provided. The SPIN operating system enables system services to be defined in an application-specific fashion through an extensible microkernel. It offers applications fine-grained control over a machine's logical and physical resources through run-time adaptation of the system to application requirements.

Method for controlling the locking and unlocking of system resources in a shared resource distributed computing environment

Abstract: A method of and system for optimizing process utilization in a shared resource environment that avoids holding system processes while requests are queued or waiting for system resources. Information about a waiting request is retained in control structures; then the same process that frees a resource is utilized to respond to queued requests for that resource. The effect is to minimize the retention and/or allocation of processes and their associated system resource requirements. The same method is applied to the synchronization of interprocess communications.

QOS provisioning in micro-cellular networks supporting multimedia traffic

Abstract: We introduce an adaptive call admission control mechanism for wireless/mobile networks supporting multimedia traffic, and discuss a number of resource sharing schemes which can be used to allocate wireless bandwidth to different classes of traffic. The adaptive call admission control reacts to changing new call arrival rates, and the resource sharing mechanism reacts to rapidly changing traffic conditions in every radio cell due to mobility of mobile users. In addition, we have provided an analytical methodology which shows that the combination of the call admission control and the resource sharing schemes guarantees a predefined quality-of-service to each class of traffic. One major advantage of our approach is that it can be performed in a distributed fashion removing any bottlenecks that might arise due to frequent invocation of network call control functions.

Resource sharing for multi-party real-time communication

Abstract: Approaches to supporting real-time communication allocate network resources either to individual connections, or to aggregates of connections. Resource sharing is a new approach that exploits known relationships between related connections to allow network resources to be shared between them without sacrificing well-defined guarantees. The authors present a fully distributed technique for using resource sharing to provide guaranteed performance communication in a heterogeneous internetwork. Results show that resource sharing leads to a large gain in the connection acceptance rate, and a significant reduction in the computational overhead associated with admission control. Thus, resource sharing is an important tool for providing real-time performance guarantees for large conferences.

Hierarchical modeling of availability in distributed systems

Abstract: Distributed computing systems are attractive due to the potential improvement in availability, fault-tolerance, performance, and resource sharing. Modeling and evaluation of such computing systems is an important step in the design process of distributed systems. We present a two-level hierarchical model to analyze the availability of distributed systems. At the higher level (user level), the availability of the tasks (processes) is analyzed using a graph-based approach. At the lower level (component level), detailed Markov models are developed to analyze the component availabilities. These models take into account the hardware/software failures, congestion and collisions in communication links, allocation of resources, and the redundancy level. A systematic approach is developed to apply the two-level hierarchical model to evaluate the availability of the processes and the services provided by a distributed computing environment. This approach is then applied to analyze some of the distributed processes of a real distributed system, Unified Workstation Environment (UWE), that is currently being implemented at AT&T Bell Laboratories. >

Failure recovery apparatus and method for distributed processing shared resource control

Abstract: Communicating the failure of master process controlling one or more shared resources to all processes sharing the resources. A shared resource control file is established that contains the identities of all sharing processes. Master process failure triggers a race to establish exclusive access over the shared control file. The new master reads shadow address data from the old shared control file, marks it as invalid and establishes a new control file based on renewed registrations from the sharing processes. The master process maintains the sharing process list as process begin and end sharing.

Allocation sequences of two processes sharing a resource

Abstract: We study a Petri net model of a system composed of two processes sharing a resource. Conflicts may occur over the usage of the shared resource, thus making the system nondeterministic. Therefore, in the context of minimax algebra, it cannot be formulated as a linear system in order to compute its performance measures. However, if the sequence by which the resource is allocated to the two processes is known, we can transform the system into a decision-free net. For this system with an imposed constraint on the resource allocation frequencies, we show that the optimal allocation sequence is the most regular integer sequence satisfying that constraint. We also discuss the periodic behavior of this system under no constraints on the resource allocation frequencies. >

Coordinated multilateral trades for electric power networks

Abstract: The authors focus on how to operate a power system to achieve economically efficient generation and consumption in a network where the integrity of the network operation has to be maintained. The power network is treated as a shared resource used by the parties connected to it. The owner of the network and the operator of the network provide a service to the generators and consumers using the network and should be compensated. The compensation issue, or the transmission pricing issue, has not been addressed. The merchandising surplus in the coordinated multilateral trading model, i.e. the difference between the total benefit for consumers and the total cost for generators in the whole network, represent the profit made by the participants and should be used to compensate the transmission network owner and operator. This is a subject of further research.

Method for deadlock recovery using consistent global checkpoints

Abstract: A method for deadlock recovery in a shared resource multiprocess message passing computer system The processes executing in the computer system perform periodic local checkpoints and communicate via inter-process messages Upon detection of a deadlock in the computer system, inter-process rollback dependency is analyzed in order to choose a resource to reclaim The choice of a resource to reclaim is made such that a resource manager which manages the resource can be rolled back so as to reclaim the resource, and such that an application process which is waiting for the resource is not rolled back past the point at which deadlock was detected Thus, upon system restart, the reclaimed resource can be provided to the waiting process, and the waiting process can execute past the deadlock point In one embodiment, the recovery line is determined by selecting appropriate checkpoints from a resource manager process and an application process, and determining the most recent consistent global checkpoint which contains the selected checkpoints

Exclusive control unit for a resource shared among computers

Abstract: The invention provides an exclusive control unit among computers which can reliably perform an exclusive control for a shared resource while keeping a system running as a whole even if a problem occurs in any of the computers in the system. Each of the computers is connected to the others through a LAN and to a distributed shared memory bus for connecting each distributed shared memory card mounted on each computer with the others. The distributed shared memory card has a distributed shared memory, which shares the shared resource with the other distributed shared memories, and a distributed shared memory controller which is connected with the distributed shared memory bus for making it possible to exchange data among the distributed shared memories mounted on the computers, an I/O bus inside its own computer, and its distributed shared memory, through its internal bus, and the distributed shared memory card performs an exclusive control for the shared data which is shared among the respective computers and exchanged among them through the distributed shared memory bus.

Floor Control for Activity Coordination in Networked Multimedia Applications

Abstract: : Collaboration in networked multimedia applications requires means to coordinate the activities of a dynamically aggregating set of distributed users, working with various multimedia data on heterogeneous platforms. A floor denotes a control right over a shared resource within a collaborative workspace. Floor control, similar to concurrency control for databases, is gradually being integrated into shared applications to orchestrate the access and dynamic process of joint work on shared data, supporting or substituting a human conference chair. This paper presents a comprehensive view on floor control, analyzing requirements for protocols with respect to the variety of shared tools, describing an architecture to meet these requirements, and finally placing our work in the context of previous efforts.

Loosely coupled compound computer system using lock and semaphore mechanism for performing exclusive control of shared resource which is accessed through a distinct bus

Abstract: Exclusive control using a semaphore mechanism of a specific computer is executed, and P and V operation instructions for the semaphore mechanism are issued according to a use request and use end information of a shared resource from another computer or the specific computer. Whether or not enabling information for the use request is informed to a use request source computer is determined according to the value of a semaphore variable. For this reason, even when a use of the shared resource is not enabled, enabling information is merely not sent back to another computer or the specific computer as the request source computer, and a lock server mechanism can be prevented from being set in an execution waiting state according to the unsuccessful P operation instruction.

Method and apparatus for improved throughput in a multi-node communication system with a shared resource

Abstract: A non-quota access indicator is circulated among nodes in a multi-node quota based communication system with a shared resource, indicating maximum possible non-quota access to the shared resource to a given node receiving same. Upon arrival at a node, the indicator is saved and then updated to reflect the current status of that node as either starved or satisfied, the former being a condition of currently having quota remaining and a shared resource access requirement, and the latter being a condition of either currently having no remaining quota or having no current shared resource access requirement. After updating, the node immediately propagates the indicator to the next node in the system. When a node without quota requires access to the shared resource, it compares its requirement to the last stored indicator and accesses the shared resource if the stored indicator is equal to or greater than the access requirement.

BASEMENT: a distributed real-time architecture for vehicle applications

Abstract: The paper presents BASEMENT, a distributed real time architecture developed for vehicle internal use in the automotive industry. The BASEMENT concept is holistic, in the sense that it covers application development, as well as the hardware and software that provide execution and communication support. The key constituents of the concept are: resource sharing (multiplexing) of processing and communication resources; a guaranteed real time service for safety critical applications; a best effort service for nonsafety critical applications; a communication infrastructure providing efficient communication between distributed devices; and a program development methodology allowing resource independent and application oriented development of application software. A real time kernel supporting BASEMENT has been developed, together with two design tools: a system simulator and an offline scheduler. We illustrate BASEMENT system development by presenting an intelligent cruise control application.

Implementing a shared file system on a HIPPI disk array

Abstract: Shared file systems which use a physically shared mass storage device have existed for many years, although not on UNIX based operating systems. This paper describes a shared file system (SFS) that was implemented first as a special project on the Gray Research Inc. (CRI) UNICOS operating system. A more general product was then built on top of this project using a HIPPI disk array for the shared mass storage. The design of SFS is outlined, as well as some performance experiences with the product. We describe how SFS interacts with the OSF distributed file service (DFS) and with the CRI data migration facility (DMF). We also describe possible development directions for the SFS product.

System and method for failure recovery in a shared resource system having a moving write lock

Abstract: The system and method of the present invention provides for recovery from failure of a distributed processing system process designated as a master process for at least one shared resource. The system of the invention provides for detection of the failure by one or more of the shadow processes. The detecting process tests to determine whether it has the shared write lock managed by the master process. If it does, it becomes the master process. If not, it determines from the shared control file which process holds the write lock and it communicates to that process a request to assume master process responsibilities.

Incorporating input/output operations into dynamic data-flow graphs

Abstract: Driven by the ‘side-effect’ environment of sequential von Neumann computing, Input/Output operations have evolved as state operations on shared files. In parallel programs, if multiple instances of an I/O-performing process execute concurrently, either the user or the system must synchronize any accesses to shared files. Data-flow principles of execution provide an elegant way to ensure at runtime that instructions can be executed asynchronously in a parallel environment. However, while the conventional von Neumann model of interpretation inherited a rigid ordering of instructions, it is the very asynchronous character of the data-flow model of execution which introduces conflicts when ‘state’ tasks (such as I/O operations) must share common data objects. The scheme presented in this paper, Logical Serialization with Distributed File Pointers (LS-DFP), introduces the two basic I/O operations read and write into the dynamic data-flow graph. However, sequencing I/O operations on the same file based on the availability of data as in ‘conventional’ data-flow is not possible because the name of the file becomes available simultaneously to all operations at program initiation. To impose an order, we sequentialize, (logically serialize-LS), the operations according to their lexicographical ordering. Furthermore, several optimizations are introduced that allow the distributed execution of these I/O operations with the use of Distributed File Pointers (DFP). Thus, the LS-DFP scheme can utilize the full level of parallelism of the dynamic data-flow principles of execution.

Priority arbitration protocol with two resource requester classes and system therefor

Abstract: An arbitration protocol (68) comprises the steps of receiving a first (70) and a second (74) plurality of resource request signals, and either, granting the shared resource to a selected one of a first plurality of resource users (72) or granting the shared resource to a selected one of a second plurality of resource users (76). A differing one of each of a first plurality of resource users and of each of a second plurality of resource users generates a differing one of the first plurality of resource request signals and a differing one of the second plurality of resource request signals, respectively. Each one of the first and the second plurality of resource request signals corresponds to a first logic state if a particular one of the first or second plurality of resource users requests use of a shared resource. The shared resource is granted to a selected one of the first plurality of resource users according to a first arbitration protocol if at least one of the first plurality of resource request signals corresponds to the first logic state. The shared resource is granted to a selected one of the second plurality of resource users according to a second arbitration protocol if none of the first plurality of resource request signals corresponds to the first logic state and at least one of the second plurality of resource request signals corresponds to the first logic state.

Pseudo-concurrent access to a cached shared resource

Abstract: A method and apparatus for efficiently controlling the access to a cached shared resource such as dynamic random access memory (DRAM). The access is effected in a pseudo-concurrent manner by two devices such as a central processing unit (CPU) and a bus master agent. While one device accesses data stored in the DRAM, the other device accesses a copy of the DRAM data which is stored in the cache of the shared resource.

Statistical multiplexing and buffer sharing in multimedia high-speed networks: a frequency domain perspective

Abstract: An essential feature of the ATM-based solution for BISDN is its potential to use the same set of network resources to support a vast variety of user services. We study the effectiveness of statistical multiplexing and buffer sharing under the multimedia high-speed networking environment. We focus on the impact of frequency domain source characteristics on dynamic resource-sharing. By applying a novel statistical matching technique, we can, for the first time, investigate the multiplexing performance of a wide-range of realistic traffic sources using sophisticated traffic models. It has been shown that the effectiveness of statistical multiplexing and buffer sharing highly depends on the frequency domain characteristics of the traffic as well as the corresponding QoS requirements. For practical "low-frequency" sources, e.g. VBR-video streams and LAN-to-LAN traffic, significant savings in bandwidth and buffer-space can be achieved via resource sharing under practical loss and delay constraints. These findings re-illustrate the important role of traffic characteristics in the design/selection of network control strategies. The trade-offs among different design alternatives (e.g. multiplexing vs. buffering) and the implications on some control schemes, e.g. traffic shaping/input-rate control, are also discussed.

Essential factors for full-interactive VOD server: video file system, disk scheduling, network

Abstract: There are many problems to be solved for realizing full-interactive on-demand service. It is essential to increase the number of simultaneously accessible streams, achieve time control of the delivering streams, and be able to deliver requested titles and serve trick plays with a quick response. A method to solve each of these problems is proposed, in terms of the video file system, disk scheduling, and the network. A prototypical VOD system is constructed, which includes an interactive network-interface, application protocols and title management. It is confirmed that these proposals are feasible.

Multi-level token management for distributed file systems

Abstract: A system and method for controlling access to shared resources in a distributed computer system. Access to shared resources is controlled by a local authorization token manager. Only computer processes holding authorization tokens for the requested operation may perform that operation. Each requested operation checks for the proper token. If the token is not held by the process, it is requested. The local token manager resolves token conflicts before granting tokens. A token manager of a distributed file system export protocol also is able to request authorization tokens from the local token manager. The export protocol token manager controls authorization tokens for that particular distributed file system protocol. Multiple different export protocols may request tokens from the local token manager. The shared resources may therefore be shared by multiple different export protocols without conflict. Local processes and processes requesting shared resource operations through an export protocol that does not itself manage tokens are granted tokens through the operation token request mechanism. This mechanism enables local processes to use shared resources without the performance penalty of having to request through a local distributed client process.

Networks and their Applications

Abstract: Computer networks increase interconnectivity at the organizational level and are advancing rapidly in terms of their technological speed and capacity. Computer networks provide to users resource sharing and computer mediated communication. Computer-mediated communication systems include computer conferencing and electronic mail. Resource sharing allows users to access and use resources on another computer that they cannot directly (in physical terms) access [151]. This chapter explores the features of a network, the special demands of multimedia on networks, electronic mail, internet tools, and more.

Networks and Resource Sharing in the 21st Century: Re-Engineering the Information Landscape

Abstract: Visionary thinkers reflect on key aspects of the contemporary information landscape in Networks and Resource Sharing in the 21st Century. In this thought-provoking volume, contributing authors provide multiple lenses from different industry viewpoints to help readers understand current opportunities and challenges facing information providers and their organizations. These authors provide analysis, propose inventions, cite barriers, and target opportunities, stimulating readers to devise solutions appropriate to their personal situations. The book considers the changing face of resource sharing within the context of a rapidly exploding information landscape, and it investigates critical dimensions of network developments as they relate to access and delivery of data and "documents" in multiple media. It helps readers understand the escalating changes which are irrevocably altering their professional environment and information access choices. Networks and Resource Sharing in the 21st Century is divided into three sections. Contextual Viewpoints sets the stage for considering the subject. Converging Technologies discusses converging computing and telecommunications technologies which promise to transform information systems as they are known today. Musts, Can'ts, and Myths investigates implications of today's emerging trends for information professionals’ futures. Topics addressed in individual chapters include:an examination of the library environment and the work of librarians in the emerging digital worldmodels of strategic issue analysis and their applicability to past, present, and future issues related to library networkingthe effect of multimedia technology on sharing of resources, and issues and barriers associated with multimediasci-tech information resources and information networks in Western Europethe future of bibliographic utilitiesthe future of digital collections. Networks and Resource Sharing in the 21st Century provides a much-needed context to aid readers as they shape the resource sharing environment of tomorrow. It is a stimulating guide for practicing librarians, MLS students, and network staff as they strive to make libraries and information centers a vital part of the future.

Resource sharing : Need for bridging gap between idealistic theoretical slogans and practitioners' lax

Abstract: It is everybody's knowledge that resource sharing is most talked and least practiced area in librarianship. Several idealistic theoretical slogans have been repeated again and again and many master plans have remained on paper in the custody of planners. These grand ideas and plans are threatening individual libraries that if they do not act they are going to starve and die in the information drought. Even after hearing about the benefits of cooperation and resource sharing egoistic, suspicious and lax attitude on the part of people at the helm of affairs have not yet been overcome. No body is worried about this widening gap between plans and practice of resource sharing. There are clear reasons for the gap between what has been said about resource sharing and what has been achieved so far. This paper, while examining both the high sounding theoretical plans of resource sharing and the practical barriers to resource sharing, explore the inherent limitations of resource sharing philosophy, presents the important factors which militate against resource sharing and how to face and overcome them in a working environment with anecdotes and case studies. What matters much in the game is gracefully accepting the limitations, using appropriate mode of management with least external interference, underscoring the cost saving objective, avoiding buck passing, 'something for nothing syndrome' and empty promises of only bibliographic access without physical access to text and understanding that communication and networks are only means and not ends.