Download or read book A Consistency Model for Distributed Shared Memory on RHODOS Among Shared Memory Consistency Models written by J. Silcock and published by . This book was released on 1996 with total page 11 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Distributed Shared Memory Consistency Models written by Venkateswarlu Chennareddy and published by Independently Published. This book was released on 2024-02-07 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book talks about the Specification and Verification of Distributed Shared Memory Relaxed Consistency Models specifically Weak Consistency Models. For this, an abstract Distributed Shared Memory (DSM) has been designed and implemented using CADP (Construction and Analysis of Distributed Processes). In DSM, sequential consistency unnecessarily reduces the performance of the system because it does not allow reordering or pipelining the memory operations. Weak consistency allows the reordering of memory events and buffering or pipelining of memory accesses so weak consistency improves the performance of the DSM system. For any critical system, it is very important to develop methods that increase our confidence in the correctness of such systems. One such method for the correctness of critical systems is formal verification. For verification of the weak consistency model, the properties of weak consistency have been specified and verified on the Abstract DSM System using CADP Toolbox.
Download or read book Shared Memory Consistency Models written by Abdul Naeem and published by LAP Lambert Academic Publishing. This book was released on 2013 with total page 260 pages. Available in PDF, EPUB and Kindle. Book excerpt: The shared memory systems should support parallelization at the computation (multiprocessor), communication (Network-on-Chip, NoC) and memory architecture levels to exploit the potential performance benefits. Such systems are facing the critical issues of memory consistency and coherence. Memory consistency issue arises due to the unconstrained operations which sometimes lead to the unexpected behavior of the systems. Memory consistency models are used to resolve this issue. Relaxed or weaker consistency models enforce less ordering constraints on the memory operations and exploit system optimizations compared to the stricter models. This book discusses the novel realization schemes and scalability analysis of strict Sequential Consistency (SC) model and relaxed memory consistency models: Total Store Ordering (TSO), Partial Store Ordering (PSO), Weak Ordering (WO), Release Consistency (RC), and Protected Release Consistency (PRC) in the NoC based distributed shared memory multiprocessor systems. This study should help the average readers and professionals to understand the critical issue of memory consistency both in the NoC based systems and general purpose multiprocessor systems.
Download or read book Comparative Study of Various Consistency Models in Distributed Shared Memory System written by Sindhu Singh and published by . This book was released on 2010 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Distributed Shared Memory (DSM) is a collection of nodes or clusters, each with its own memory connected by an interconnected network. The key issue in DSM is keeping the memory pages consistent. It refers to the degree of consistency that has to be maintained for the shared memory data. Maintaining perfect consistency is especially painful when the difference between the latency and/or throughput of memory accesses on the one hand, and the network connecting the machines on which these copies reside on the other, is big. The solution might be to accept less than perfect consistency as the price for better performance. This paper reviews various memory consistency models which are used in different DSM systems.
Download or read book Distributed Shared Memory and Data Consistency written by Krzysztof Piotrowski and published by Sudwestdeutscher Verlag Fur Hochschulschriften AG. This book was released on 2012-03 with total page 284 pages. Available in PDF, EPUB and Kindle. Book excerpt: This work investigates the feasibility of data consistency models to be used in Distributed Shared Memory (DSM) for Wireless Sensor Networks (WSN) to enable more powerful distributed systems with reliable data exchange. It starts with an introduction of WSN and consistency related approaches. Based on these basics, mechanisms that enable data consistency are discussed as a theoretical framework for the prototypical implementation of a data consistency providing middleware that was implemented as part of this work. The proposed middleware adapts the mechanisms known from the original memory consistency approaches to make them usable in the sensor network area and also proposes own low cost mechanisms. The latter are at least partially based on the idea that within the shared memory in WSNs the information is the major concern and by that the replica update rates can be tailored to the application. In order to allow for ease of use of the middleware, the replication schemes and the consistency mechanisms are defined by the application engineer as a policy. The most appropriate memory consistency models were implemented and evaluated using the framework proposed in this work.
Download or read book A Primer on Memory Consistency and Cache Coherence written by Daniel Sorin and published by Morgan & Claypool Publishers. This book was released on 2011-03-02 with total page 214 pages. Available in PDF, EPUB and Kindle. Book excerpt: Many modern computer systems and most multicore chips (chip multiprocessors) support shared memory in hardware. In a shared memory system, each of the processor cores may read and write to a single shared address space. For a shared memory machine, the memory consistency model defines the architecturally visible behavior of its memory system. Consistency definitions provide rules about loads and stores (or memory reads and writes) and how they act upon memory. As part of supporting a memory consistency model, many machines also provide cache coherence protocols that ensure that multiple cached copies of data are kept up-to-date. The goal of this primer is to provide readers with a basic understanding of consistency and coherence. This understanding includes both the issues that must be solved as well as a variety of solutions. We present both highlevel concepts as well as specific, concrete examples from real-world systems. Table of Contents: Preface / Introduction to Consistency and Coherence / Coherence Basics / Memory Consistency Motivation and Sequential Consistency / Total Store Order and the x86 Memory Model / Relaxed Memory Consistency / Coherence Protocols / Snooping Coherence Protocols / Directory Coherence Protocols / Advanced Topics in Coherence / Author Biographies
Download or read book Verifying Memory Consistency Models for DSM System written by Pankaj Kumar and published by . This book was released on 2013 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The parallelism of Distributed Shared Memory (DSM) system can be improved by data replication. A DSM system sends data from one node to another via a network. So for replication of data, maintenance of memory consistency is required. The maintenance of memory consistency can be done by a proper memory consistency model with the help of coherence protocol. Although a lot of research has been done for the maintenance of memory consistency using a consistency model, a specific memory model is not given in literature; but it has been taken randomly. However, in this paper, it is described in a unified framework. So this paper aims at analyzing some memory consistency models and finding the perfect model for DSM system architecture based on write-update coherence protocol.
Download or read book Consistent Distributed Storage written by Vincent Gramoli and published by Springer Nature. This book was released on 2022-05-31 with total page 176 pages. Available in PDF, EPUB and Kindle. Book excerpt: Providing a shared memory abstraction in distributed systems is a powerful tool that can simplify the design and implementation of software systems for networked platforms. This enables the system designers to work with abstract readable and writable objects without the need to deal with the complexity and dynamism of the underlying platform. The key property of shared memory implementations is the consistency guarantee that it provides under concurrent access to the shared objects. The most intuitive memory consistency model is atomicity because of its equivalence with a memory system where accesses occur serially, one at a time. Emulations of shared atomic memory in distributed systems is an active area of research and development. The problem proves to be challenging, and especially so in distributed message passing settings with unreliable components, as is often the case in networked systems. We present several approaches to implementing shared memory services with the help of replication on top of message-passing distributed platforms subject to a variety of perturbations in the computing medium.
Download or read book Distributed Shared Memory written by Jelica Protic and published by John Wiley & Sons. This book was released on 1997-08-10 with total page 384 pages. Available in PDF, EPUB and Kindle. Book excerpt: The papers present in this text survey both distributed shared memory (DSM) efforts and commercial DSM systems. The book discusses relevant issues that make the concept of DSM one of the most attractive approaches for building large-scale, high-performance multiprocessor systems. The authors provide a general introduction to the DSM field as well as a broad survey of the basic DSM concepts, mechanisms, design issues, and systems. The book concentrates on basic DSM algorithms, their enhancements, and their performance evaluation. In addition, it details implementations that employ DSM solutions at the software and the hardware level. This guide is a research and development reference that provides state-of-the art information that will be useful to architects, designers, and programmers of DSM systems.
Download or read book Modeling Sequential Consistency in a Distributed Shared Memory System written by Christoph Lindemann and published by . This book was released on 1991 with total page 38 pages. Available in PDF, EPUB and Kindle. Book excerpt: The compact DSPN is employed for a quantitative performance analysis of the sequential consistency protocol. A detailed evaluation of the sequential consistency protocol is presented which give [sic] important hints for designing more relaxed consistency models."
Download or read book Emphasizing Distributed Systems written by and published by Academic Press. This book was released on 2000-06-29 with total page 553 pages. Available in PDF, EPUB and Kindle. Book excerpt: As the computer industry moves into the 21st century, the long-running Advances in Computers is ready to tackle the challenges of the new century with insightful articles on new technology, just as it has since 1960 in chronicling the advances in computer technology from the last century. As the longest-running continuing series on computers, Advances in Computers presents those technologies that will affect the industry in the years to come. In this volume, the 53rd in the series, we present 8 relevant topics. The first three represent a common theme on distributed computing systems -using more than one processor to allow for parallel execution, and hence completion of a complex computing task in a minimal amount of time. The other 5 chapters describe other relevant advances from the late 1990s with an emphasis on software development, topics of vital importance to developers today- process improvement, measurement and legal liabilities. - Longest running series on computers - Contains eight insightful chapters on new technology - Gives comprehensive treatment of distributed systems - Shows how to evaluate measurements - Details how to evaluate software process improvement models - Examines how to expand e-commerce on the Web - Discusses legal liabilities in developing software—a must-read for developers
Download or read book A Primer on Memory Consistency and Cache Coherence written by Vijay Nagarajan and published by Morgan & Claypool Publishers. This book was released on 2020-02-04 with total page 296 pages. Available in PDF, EPUB and Kindle. Book excerpt: Many modern computer systems, including homogeneous and heterogeneous architectures, support shared memory in hardware. In a shared memory system, each of the processor cores may read and write to a single shared address space. For a shared memory machine, the memory consistency model defines the architecturally visible behavior of its memory system. Consistency definitions provide rules about loads and stores (or memory reads and writes) and how they act upon memory. As part of supporting a memory consistency model, many machines also provide cache coherence protocols that ensure that multiple cached copies of data are kept up-to-date. The goal of this primer is to provide readers with a basic understanding of consistency and coherence. This understanding includes both the issues that must be solved as well as a variety of solutions. We present both high-level concepts as well as specific, concrete examples from real-world systems. This second edition reflects a decade of advancements since the first edition and includes, among other more modest changes, two new chapters: one on consistency and coherence for non-CPU accelerators (with a focus on GPUs) and one that points to formal work and tools on consistency and coherence.
Download or read book Relaxing Consistency in Recoverable Distributed Shared Memory written by and published by . This book was released on 1993 with total page 9 pages. Available in PDF, EPUB and Kindle. Book excerpt: Relaxed memory consistency models tolerate increased memory access latency in both hardware and software distributed shared memory systems. In recoverable systems, relaxing consistency has the added benefit of reducing the number of checkpoints needed to avoid rollback propagation. In this paper, we introduce new checkpointing algorithms that take advantage of relaxed consistency to reduce the performance overhead of checkpointing. We also introduce a scheme based on lazy relaxed consistency, that reduces both checkpointing overhead and the overhead of avoiding error propagation in systems with error latency. We use multiprocessor address traces to evaluate the relaxed consistency approach to checkpointing with distributed shared memory.
Download or read book Views and Consistencies in Distributed Shared Memory written by Gabriel Girard and published by . This book was released on 2000 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The distributed shared memory (DSM) abstraction is a very popular programming paradigm in parallel and distributed environments. However, DSM often suffers from performance problems as consistency requirements often incur long access latencies that cannot be overlapped with other operations in a process. Sequential consistency is the most general consistency requirement for DSM systems. This thesis explores two different avenues to solve the performance problem for DSM systems. First, for sequentially consistent DSM, we introduce a new strategy to minimize synchronization cost and maximize the hiding of synchronization delays in a process. The strategy is based on the knowledge of spatial locality in the sharing of memory objects. An access graph is used to capture the sharing relationship among processes via the shared objects. We show that if accesses in all cycles are 'properly' synchronized, then the execution is guaranteed to be sequentially consistent. We develop two distinct solution strategies to ensure proper synchronization. (i) Neighbor protocol: conflicting accesses between two neighbors in an access cycle must be synchronized, and (ii) flush protocol: asynchronous accesses in an access cycle must be eventually synchronized by a special flush-access in the cycle. Simulation experiments have shown significant improvements in performance in our protocols, especially in the case of the flush protocol. Another strategy to improve performance of DSM systems is to adopt a weaker consistency model so that blocking among some memory operations can be removed. In this thesis, we use the primitive notion of program-order and value-order to define global view. Using this as a seed, various consistency models evolve and form multiple hierarchies of models. The creation of these models and hierarchies comes via one of the following means: (i) a global view is augmented with additional ordering among its operations whenever some orderings exist, or (ii) besides linearizability of a global view, certain orderings must not co-exist in it. The former involves augmentation rules, and the latter involves causality requirements. The creation of these hierarchies leads to several novel consequences: the notion of exact implementation is introduced, new protocols are discovered and the precise analysis of access behaviors of an application is now possible.
Download or read book Designing Memory Consistency Models for Shared memory Multiprocessors written by Sarita V. Adve and published by . This book was released on 1993 with total page 434 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Eureka written by Joao Alberto Vianna Tavares and published by . This book was released on 1995 with total page 116 pages. Available in PDF, EPUB and Kindle. Book excerpt: Distributed Shared Memory (DSM) provides an abstraction of shared memory on a network of workstations. Problems with existing DSM systems are lack of portability due to compiler and/or operating system modification requirements, and reduced performance due to significant synchronization and communication costs when compared to their message passing counterparts (e.g., PVM and MPI). Our approach was to introduce a new DSM consistency model, Lazy Data Merging (LDM), which extends Data Merging (DM). LDM is optimized for software runtime implementations and differs from DM by 'lazily' placing data updates across the communication network only when they are required. It is our belief that LDM can significantly reduce communication costs, particularly for applications that make extensive use of locks. We have completed the design of "Eureka", a prototype DSM system that provides a software implementation of the LDM consistency model. To ensure portability and efficiency we use only standard UniXTM system calls and a publicly available software thread package, Cthreads, from the University of Utah. Furthermore, we have implemented and tested some of Eureka's core components, specifically, the set of communication and hybrid (Invalidate/Update) coherence primitives, which are essential for follow on work in building the complete DSM system. The question of efficiency is still an open problem, because we did not compare Eureka with other DSM implementations.
Download or read book Support for Software Distributed Shared Memory on Clusters of Heterogeneous Workstations written by Subhabrata Saha and published by . This book was released on 2002 with total page 40 pages. Available in PDF, EPUB and Kindle. Book excerpt:
