Download or read book Design and Analysis of Update Based Cache Coherence Protocols for Scalable Shared Memory Multiprocessors written by David Brian Glasco and published by . This book was released on 1994 with total page 384 pages. Available in PDF, EPUB and Kindle. Book excerpt: Overall, this work demonstrates that update-based protocols can be used not only as a coherence mechanism, but also as a latency reducing and tolerating technique to improve the performance of a set of fine-grain scientific applications. But as with other latency reducing techniques, such as data prefetch, the technique must be used with an understanding of its consequences.
Download or read book Design and Validation of Update based Cache Coherence Protocols written by Stanford University. Computer Systems Laboratory and published by . This book was released on 1994 with total page 36 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this paper, we present the details of the two update-based cache coherence protocols for scalable shared-memory multiprocessors that were studied in our previous work. First, the directory structures required for the protocols are briefly reviewed. Next, the state diagrams and some examples of the two update-based protocols are presented; one of the protocols is based on a centralized directory, and the other is based on a singly-linked distributed directory. Protocol deadlock and the additional requirements placed the protocols to avoid such deadlock are also examined. Finally, protocol validation using an exhaustive validation tool known as Murphi is discussed.
Download or read book Update based Cache Coherence Protocols for Scalable Shared memory Multiprocessors written by Stanford University. Computer Systems Laboratory and published by . This book was released on 1993 with total page 26 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this paper, two hardware-controlled update-based cache coherence protocols are presented. The paper discusses the two major disadvantages of the update protocols: inefficiency of updates and the mismatch between the granularity of synchronization and the data transfer. The paper presents two enhancements to the update-based protocols, a write combining scheme and a finer grain synchronization, to overcome these disadvantages. The results demonstrate the effectiveness of these enhancements that, when used together, allow the update-based protocols to significantly improve the execution time of a set of scientific applications when compared to three invalidate-based protocols.
Download or read book Cache and Interconnect Architectures in Multiprocessors written by Michel Dubois and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 286 pages. Available in PDF, EPUB and Kindle. Book excerpt: Cache And Interconnect Architectures In Multiprocessors Eilat, Israel May 25-261989 Michel Dubois UniversityofSouthernCalifornia Shreekant S. Thakkar SequentComputerSystems The aim of the workshop was to bring together researchers working on cache coherence protocols for shared-memory multiprocessors with various interconnect architectures. Shared-memory multiprocessors have become viable systems for many applications. Bus based shared-memory systems (Eg. Sequent's Symmetry, Encore's Multimax) are currently limited to 32 processors. The fIrst goal of the workshop was to learn about the performance ofapplications on current cache-based systems. The second goal was to learn about new network architectures and protocols for future scalable systems. These protocols and interconnects would allow shared-memory architectures to scale beyond current imitations. The workshop had 20 speakers who talked about their current research. The discussions were lively and cordial enough to keep the participants away from the wonderful sand and sun for two days. The participants got to know each other well and were able to share their thoughts in an informal manner. The workshop was organized into several sessions. The summary of each session is described below. This book presents revisions of some of the papers presented at the workshop.
Download or read book A Primer on Memory Consistency and Cache Coherence written by Daniel J. Sorin and published by Morgan & Claypool Publishers. This book was released on 2011 with total page 215 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 The Cache Coherence Problem in Shared Memory Multiprocessors written by Igor Tartalja and published by Wiley-IEEE Computer Society Press. This book was released on 1996-02-13 with total page 368 pages. Available in PDF, EPUB and Kindle. Book excerpt: The book illustrates state-of-the-art software solutions for cache coherence maintenance in shared-memory multiprocessors. It begins with a brief overview of the cache coherence problem and introduces software solutions to the problem. The text defines and details static and dynamic software schemes, techniques for modeling performance evaluation mechanisms, and performance evaluation studies.
Download or read book Cache Coherence for Scalable Shared Memory Multiprocessors written by Manu Thapar and published by . This book was released on 1991 with total page 274 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Eliminating Useless Messages in Write update Protocols on Scalable Multiprocessors written by University of Rochester. Department of Computer Science and published by . This book was released on 1994 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: "Cache coherence protocols for shared-memory multiprocessors use invalidations or updates to maintain coherence across processors. Although invalidation protocols usually produce higher miss rates, update protocols typically perform worse. Detailed simulations of these two classes of protocol show that the excessive network traffic caused by update protocols significantly degrades performance, even with infinite bandwidth. Motivated by this observation, we categorize the coherence traffic in update-based protocols and show that, for most applications, more than 90% of all updates generated by the protocol are unnecessary. We identify application characteristics that generate useless update traffic, and compare the isolated and combined effects of several software and hardware techniques for eliminating useless updates. These techniques include dynamic and static hybrid protocols, false sharing elimination strategies, and coalescing write buffers. Our simulations show that software caching (where coherence is managed under programmer or compiler control) and the dynamic hybrid protocol reduce useless updates the most, but coalescing write buffers produce fewer, albeit larger, coherence messages. As a result, coalescing write buffers usually produce the best running time, except when the block size is large or the bandwidth is limited. Finally, based on the observation that the techniques we consider are unable to eliminate a large number of useless updates, we suggest directions for further reducing the useless traffic in update-based protocols."
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 Evaluation of Design Alternatives for a Directory based Cache Coherence Protocol in Shared memory Multiprocessors written by Håkan Grahn and published by . This book was released on 1995 with total page 18 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Eliminating Useless Messages in Write update Protocols on Scalable Multiprocessors written by University of Rochester. Dept. of Computer Science and published by . This book was released on 1994 with total page 30 pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: "Cache coherence protocols for shared-memory multiprocessors use invalidations or updates to maintain coherence across processors. Although invalidation protocols usually produce higher miss rates, update protocols typically perform worse. Detailed simulations of these two classes of protocol show that the excessive network traffic caused by update protocols significantly degrades performance, even with infinite bandwidth. Motivated by this observation, we categorize the coherence traffic in update-based protocols and show that, for most applications, more than 90% of all updates generated by the protocol are unnecessary. We identify application characteristics that generate useless update traffic, and compare the isolated and combined effects of several software and hardware techniques for eliminating useless updates. These techniques include dynamic and static hybrid protocols, false sharing elimination strategies, and coalescing write buffers. Our simulations show that software caching (where coherence is managed under programmer or compiler control) and the dynamic hybrid protocol reduce useless updates the most, but coalescing write buffers produce fewer, albeit larger, coherence messages. As a result, coalescing write buffers usually produce the best running time, except when the block size is large or the bandwidth is limited. Finally, based on the observation that the techniques we consider are unable to eliminate a large number of useless updates, we suggest directions for further reducing the useless traffic in update-based protocols."
Download or read book Scalable Shared Memory Multiprocessors written by Michel Dubois and published by Springer Science & Business Media. This book was released on 1992 with total page 360 pages. Available in PDF, EPUB and Kindle. Book excerpt: Mathematics of Computing -- Parallelism.
Download or read book Visible Synchronization Based Cache Coherence written by Krishna Kumar and published by . This book was released on 1997 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: In large scale machines, thousands of processor cycles, in other words, missed opportunities to issue floating point instructions, may be lost while waiting for a high latency synchronization or memory operation to complete, or a stall in an instruction pipeline to be dealt with. Latency is avoided by bringing data to a nearby locale for future reference (e.g., caching) while latency is tolerated by overlapping data movement with something useful. The issue of cache coherence arises whenever there are multiple copies of a shared datum in different caches of a shared-memory multiprocessor system. It is in order to maintain consistency between these multiple copies that cache coherence protocols are employed. The efficiency of latency avoidance methods is largely dependent upon the minimization of coherence traffic in the coherence protocol used to maintain cache coherency. Cache coherence protocols in general can be divided into two classes: hardware implemented ones and compiler implemented ones. Hardware implemented ones lead to large coherence traffic, and large state storage space. Conventional compiler implemented ones involve indiscriminate wasteful invalidation. There is also redundancy between synchronization operations and coherence operations. We seek to eliminate both weaknesses, by letting visible synchronization directly coordinate changes in the writability of shared data. We propose to add scalable compiler managed caches to a TERA-like multithreaded multiprocessor architecture, with user/compiler knowledge (i.e., alias analysis, dependence analysis and user directives) used to eliminate essentially all coherence traffic. To preserve scalability, we aim to use latency tolerance methods like switch-on-every-cycle multithreading, and augment this with simple, low-latency cache coherence protocols such as our visible synchronization based one.
Download or read book Co design of On chip Caches and Networks for Scalable Shared memory Many core CMPs written by Woo Cheol Kwon and published by . This book was released on 2018 with total page 180 pages. Available in PDF, EPUB and Kindle. Book excerpt: Chip Multi-Processors(CMPs) have become mainstream in recent years, providing increased parallelism as core counts scale. While a tiled CMP is widely accepted to be a scalable architecture for the many-core era, on-chip cache organization and coherence are far from solved problems. As the on-chip interconnect directly influences the latency and bandwidth of on-chip cache, scalable interconnect is an essential part of on-chip cache design. On the other hand, optimal design of interconnect can be determined by the traffic forms that it should handle. Thus, on-chip cache organization is inherently interleaved with on-chip interconnect design and vice versa. This dissertation aims to motivate the need for re-organization of on-chip caches to leverage the advancement of on-chip network technology to harness the full potential of future many-core CMPs. Conversely, we argue that on-chip network should also be designed to support specific functionalities required by the on-chip cache. We propose such co-design techniques to offer significant improvement of on-chip cache performance, and thus to provide scalable CMP cache solutions towards future many-core CMPs. The dissertation starts with the problem of remote on-chip cache access latency. Prior locality-aware approaches fundamentally attempt to keep data as close as possible to the requesting cores. In this dissertation, we challenge this design approach by introducing new cache organization that leverages a co-designed on-chip network that allows multi-hop single-cycle traversals. Next, the dissertation moves to cache coherence request ordering. Without built-in ordering capability within the interconnect, cache coherence protocols have to rely on external ordering points. This dissertation proposes a scalable ordered Network-on-Chip which supports ordering of requests for snoopy cache coherence. Lastly, we describe development of a 36-core research prototype chip to demonstrate that the proposed Network-on-Chip enables shared-memory CMPs to be readily scalable to many-core platforms.
Download or read book Scalable Shared Memory Multiprocessors written by Michel Dubois and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 326 pages. Available in PDF, EPUB and Kindle. Book excerpt: The workshop on Scalable Shared Memory Multiprocessors took place on May 26 and 27 1990 at the Stouffer Madison Hotel in Seattle, Washington as a prelude to the 1990 International Symposium on Computer Architecture. About 100 participants listened for two days to the presentations of 22 invited The motivation for this workshop was to speakers, from academia and industry. promote the free exchange of ideas among researchers working on shared-memory multiprocessor architectures. There was ample opportunity to argue with speakers, and certainly participants did not refrain a bit from doing so. Clearly, the problem of scalability in shared-memory multiprocessors is still a wide-open question. We were even unable to agree on a definition of "scalability". Authors had more than six months to prepare their manuscript, and therefore the papers included in this proceedings are refinements of the speakers' presentations, based on the criticisms received at the workshop. As a result, 17 authors contributed to these proceedings. We wish to thank them for their diligence and care. The contributions in these proceedings can be partitioned into four categories 1. Access Order and Synchronization 2. Performance 3. Cache Protocols and Architectures 4. Distributed Shared Memory Particular topics on which new ideas and results are presented in these proceedings include: efficient schemes for combining networks, formal specification of shared memory models, correctness of trace-driven simulations,synchronization, various coherence protocols, .
Download or read book A Cache Coherence Mechanism for Scalable Shared memory Multiprocessors written by University of Wisconsin--Madison. Computer Sciences Dept and published by . This book was released on 1991 with total page 21 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Scalable Shared Memory Multiprocessing written by Daniel E. Lenoski and published by Elsevier. This book was released on 2014-06-28 with total page 364 pages. Available in PDF, EPUB and Kindle. Book excerpt: Dr. Lenoski and Dr. Weber have experience with leading-edge research and practical issues involved in implementing large-scale parallel systems. They were key contributors to the architecture and design of the DASH multiprocessor. Currently, they are involved with commercializing scalable shared-memory technology.
