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 An Evaluation of Directory Protocols for Medium scale Shared memory Multiprocessors written by University of Wisconsin--Madison. Computer Sciences Dept and published by . This book was released on 1994 with total page 11 pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: "This paper considers alternative directory protocols for providing cache coherence in shared-memory multiprocessors with 32 to 128 processors, where the state requirements of Dir[subscript N] may be considered too large. We consider Dir[subscript i]B, i = 1,2,4, Dir[subscript N], Tristate (also called superset), Coarse Vector, and three new protocols. The new protocols -- Gray-hardware, Gray-software, Home -- are optimizations of Tristate that use gray coding to favor near-neighbor sharing. Our results are the first to compare all these protocols with complete applications (and the first evaluation of Tristate with a non- synthetic workload). Results for three applications -- ocean (one dimensional sharing), appbt (three-dimensional sharing), and barnes (dynamic sharing) -- for 128 processors on the Wisconsin Wind Tunnel show that (a) Dir1B sends 15 to 43 times as many invalidation messages as Dir[subscript N], (b) Gray-software sends 1.0 to 4.7 times as many messages as Dir[subscript N], making it better than Tristate, Gray- Hardware, and Home, and (c) the choice between Dir[subscript i]B, Coarse Vector, and Gray-software depends on whether one wants to optimize for few sharers (Dir[subscript i]B), many sharers (Coarse Vector), or hedge one's bets between both alternatives (Gray-software)."

Download or read book Directory Based Cache Coherency Protocols for Shared Memory Multiprocessors written by Craig Warner and published by . This book was released on 1990 with total page 190 pages. Available in PDF, EPUB and Kindle. Book excerpt: Some alternative directory entry formats are described, including a special entry format for implementing queueing semaphores. Evaluation of the various entry formats is done with probabilistic models of shared cache blocks and software simulation. A variable length global table organization is presented which can be used to reduce the size of the global table, regardless of the entry format. Its performance is analyzed using software simulation. A protocol which maintains a linked list of processors which have a particular block cached is presented. Several variations of this protocol induce less interconnection network traffic than traditional protocols."

Download or read book A Hybrid Directory based Cache Coherence Protocol for Large scale Shared memory Multiprocessors and Its Performance Evaluation written by Kwo-Yuan Shieh and published by . This book was released on 1999 with total page 250 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book LC Sim a Simulation Framework for Evaluating Location Consistency Based Cache Protocols written by Pouya Fotouhi and published by . This book was released on 2017 with total page 60 pages. Available in PDF, EPUB and Kindle. Book excerpt: New high-performance processors tend to shift from multi to many cores. More- over, shared memory has turned to dominant paradigm for mainstream multicore pro- cessors. As memory wall issue loomed over architecture design, most modern computer systems have several layers in their memory hierarchy. Among many, caches has be- come everlasting components of memory hierarchies as they signicantly reduce access time by taking the advantage of locality. ☐ Major processor vendors usually rely on cache coherence, and implement a vari- ant of MESI, e.g., MOESI for AMD, to help reduce inter-chip trac on the fast in- terconnection network. Supposedly, maintaining coherence should help with keeping parallel and concurrent programmers happy, all the while providing them with a well- known cache behavior for shared memory. This thesis challenge the assumption that Coherence is well-suited for large-scale many core processors. Seeking an alternative for coherence, LC cache protocol is extensively investigated. ☐ LC-Cache is a cache protocol weaker than Coherence, but which preserves causality. It relies on the Location Consistency (LC) model. The basic philosophy behind LC is to maintain a unique view of memory only if there is a reason to. Other ordinary memory accesses may be observed in any order by the other processors of the computer system. ☐ The motivation to stand against cache coherence, relies on underestimated lim- itations implied on system design by coherence. Observations presented in this thesis, demonstrates that coherence eliminates the possibility of having a directory based pro- tocol in practice since size of such directory grows linearly with number of cores. In addition, coherence adds implicit latency in many cases to the protocol. ☐ This thesis presents LCCSim, a simulation framework to compare cache proto- col based on location consistency against cache coherence protocols. A comparative analysis between the MESI and MOESI coherence protocols is provided, and pit them against LC-Cache. Both MESI and MOESI consistently generate more on-chip trac compared to LC cache since transitions in LC cache are done locally. However, LC cache degrades total latency of accesses as it does not take the advantage of cache to cache forwarding. Additionally, LC cache cannot be considered a true implementation based on LC since it does not behave according to the memory model. The following summarizes the contributions of this thesis: 1.Detailed specication of LC cache protocol, covering the missing aspects in the original paper. 2.A simulation framework to compare cache protocols based on LC against cache coherence protocols. 3.Extensive analysis of LC cache protocol, leading to discovery of several weak- nesses. 4.Demonstrating features for an ecient cache protocol, truly based on location consistency.

Download or read book Implementing a Directory based Cache Consistency Protocol written by Stanford University. Computer Systems Laboratory and published by . This book was released on 1990 with total page 40 pages. Available in PDF, EPUB and Kindle. Book excerpt: Directory-based cache consistency protocols have the potential to allow shared-memory multiprocessors to scale to a large number of processors. While many variations of these coherence schemes exist in the literature, they have typically been described at a rather high level, making adequate evaluation difficult. This paper explores the implementation issues of directory-based coherency strategies by developing a design at the level of detail needed to write a memory system functional simulator with an accurate timing model. The paper presents the design of both an invalidation coherency protocol and the associated directory/memory hardware. Support is added to prevent deadlock, handle subtle consistency situations, and implement a proper programming model of multiprocess execution. Extensions are delineated for realizing a multiple-threaded directory that can continue to process commands while waiting for a reply from a cache. The final hardware design is evaluated in the context of the number of parts required for implementation.

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 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 Evaluation of Directory based Cache Coherence Systems written by Brian Walter O'Krafka and published by Ann Arbor, Mich. : University Microfilms International. This book was released on 1991 with total page 398 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Cache Memory Design and Performance Issues in Shared memory Multiprocessors written by Farnaz Mounes-Toussi and published by . This book was released on 1995 with total page 358 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book A Class of Directory based Cache Coherence Protocols written by and published by . This book was released on 1993 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

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 Evaluating the Performance of Software Cache Coherence written by Susan Owicki and published by . This book was released on 1989 with total page 29 pages. Available in PDF, EPUB and Kindle. Book excerpt: In a shared-memory multiprocessor with private caches, cached copies of a data item must be kept consistent. This is called cache coherence. Both hardware and software coherence schemes have been proposed. Software techniques are attractive because they avoid hardware complexity and can be used with any processor-memory interconnection. This paper presents an analytical model of the performance of two software coherence schemes and, for comparison, snoopy-cache hardware. The model is validated against address traces from a bus-based multiprocessor. The behavior of the coherence schemes under various workloads is compared, and their sensitivity to variations in workload parameters is assessed. The analysis shows that the performance of software schemes is critically determined by certain parameters of the workload: the proportion of data accesses, the fraction of shared references, and the number of times a shared block is accessed before it is purged from the cache. Snoopy caches are more resilient to variations in these parameters. Thus when evaluating a software scheme as a design alternative, it is essential to consider the characteristics of the expected workload. The performance of the two software schemes with a multistage interconnection network is also evaluated, and it is determined that both scale well. Keywords; Computer software, Computer hardware. (kt).

Download or read book Assessment of Cache Coherence Protocols in Shared memory Multiprocessors microform written by Alexander Grbic and published by National Library of Canada = Bibliothèque nationale du Canada. This book was released on 2003 with total page 362 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Design and Evaluation of a Subblock Cache Coherence Protocol for Bus based Multiprocessors written by Graig Anderson and published by . This book was released on 1994 with total page 46 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Design Issues and Their Performance Impact in Systems with Directory based Caches written by University of Illinois at Urbana-Champaign. Center for Supercomputing Research and Development and published by . This book was released on 1992 with total page 33 pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: "Directory schemes have been proposed to solve the cache coherence problem for large-scale multiprocessor systems. Most of previous studies concentrated on cost reduction for the design of directory schemes. With scalable directory design, there are various design parameters that affect its performance. Their impact is impossible to predict. In this paper, we evaluate the effect of these parameters on the performance of directory schemes concentrating on shared data, including cache organization, directory protocols, scalability and memory latency. We also analyze the resource contention and coherence delays of directory schemes and discuss possible improvements."

Download or read book An Evaluation of Multiprocessor Cache Coherence Based on Virtual Memory Support written by Princeton University. Dept. of Computer Science and published by . This book was released on 1992 with total page 15 pages. Available in PDF, EPUB and Kindle. Book excerpt: We used trace-driven simulations to evaluate the effect of different architectural parameters on the performance of the VM-based schemes. These parameters include VM page sizes, write-back and write- through caches, memory access latencies, bus and crossbar interconnections, and differenct cache sizes. Our results show that for appropriate parameters VM-based cache coherence is an economical and practical approach for building shared-memory multiprocessors."