A Primer on Memory Consistency and Cache Coherence

Author: Daniel J. Sorin
Publisher: Morgan & Claypool Publishers
ISBN: 1608455645
Format: PDF, Docs
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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

Multi Core Cache Hierarchies

Author: Rajeev Balasubramonian
Publisher: Morgan & Claypool Publishers
ISBN: 1598297546
Format: PDF, ePub, Mobi
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A key determinant of overall system performance and power dissipation is the cache hierarchy since access to off-chip memory consumes many more cycles and energy than on-chip accesses. In addition, multi-core processors are expected to place ever higher bandwidth demands on the memory system. All these issues make it important to avoid off-chip memory access by improving the efficiency of the on-chip cache. Future multi-core processors will have many large cache banks connected by a network and shared by many cores. Hence, many important problems must be solved: cache resources must be allocated across many cores, data must be placed in cache banks that are near the accessing core, and the most important data must be identified for retention. Finally, difficulties in scaling existing technologies require adapting to and exploiting new technology constraints. The book attempts a synthesis of recent cache research that has focused on innovations for multi-core processors. It is an excellent starting point for early-stage graduate students, researchers, and practitioners who wish to understand the landscape of recent cache research. The book is suitable as a reference for advanced computer architecture classes as well as for experienced researchers and VLSI engineers. Table of Contents: Basic Elements of Large Cache Design / Organizing Data in CMP Last Level Caches / Policies Impacting Cache Hit Rates / Interconnection Networks within Large Caches / Technology / Concluding Remarks

The Memory System

Author: Bruce Jacob
Publisher: Morgan & Claypool Publishers
ISBN: 159829587X
Format: PDF, Docs
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Today, computer-system optimization, at both the hardware and software levels, must consider the details of the memory system in its analysis; failing to do so yields systems that are increasingly inefficient as those systems become more complex. This lecture seeks to introduce the reader to the most important details of the memory system; it targets both computer scientists and computer engineers in industry and in academia. Roughly speaking, computer scientists are the users of the memory system and computer engineers are the designers of the memory system. Both can benefit tremendously from a basic understanding of how the memory system really works: the computer scientist will be better equipped to create algorithms that perform well and the computer engineer will be better equipped to design systems that approach the optimal, given the resource limitations. Currently, there is consensus among architecture researchers that the memory system is "the bottleneck," and this consensus has held for over a decade. Somewhat inexplicably, most of the research in the field is still directed toward improving the CPU to better tolerate a slow memory system, as opposed to addressing the weaknesses of the memory system directly. This lecture should get the bulk of the computer science and computer engineering population up the steep part of the learning curve. Not every CS/CE researcher/developer needs to do work in the memory system, but, just as a carpenter can do his job more efficiently if he knows a little of architecture, and an architect can do his job more efficiently if he knows a little of carpentry, giving the CS/CE worlds better intuition about the memory system should help them build better systems, both software and hardware. Table of Contents: Primers / It Must Be Modeled Accurately / ...\ and It Will Change Soon

On chip Networks

Author: Natalie D. Enright Jerger
Publisher: Morgan & Claypool Publishers
ISBN: 1598295845
Format: PDF, Mobi
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With the ability to integrate a large number of cores on a single chip, research into on-chip networks to facilitate communication becomes increasingly important. On-chip networks seek to provide a scalable and high-bandwidth communication substrate for multi-core and many-core architectures. High bandwidth and low latency within the on-chip network must be achieved while fitting within tight area and power budgets. In this lecture, we examine various fundamental aspects of on-chip network design and provide the reader with an overview of the current state-of-the-art research in this field. Table of Contents: Introduction / Interface with System Architecture / Topology / Routing / Flow Control / Router Microarchitecture / Conclusions

Architectural and Operating System Support for Virtual Memory

Author: Abhishek Bhattacharjee
Publisher: Morgan & Claypool Publishers
ISBN: 1627059334
Format: PDF, ePub, Docs
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This book provides computer engineers, academic researchers, new graduate students, and seasoned practitioners an end-to-end overview of virtual memory. We begin with a recap of foundational concepts and discuss not only state-of-the-art virtual memory hardware and software support available today, but also emerging research trends in this space. The span of topics covers processor microarchitecture, memory systems, operating system design, and memory allocation. We show how efficient virtual memory implementations hinge on careful hardware and software cooperation, and we discuss new research directions aimed at addressing emerging problems in this space. Virtual memory is a classic computer science abstraction and one of the pillars of the computing revolution. It has long enabled hardware flexibility, software portability, and overall better security, to name just a few of its powerful benefits. Nearly all user-level programs today take for granted that they will have been freed from the burden of physical memory management by the hardware, the operating system, device drivers, and system libraries. However, despite its ubiquity in systems ranging from warehouse-scale datacenters to embedded Internet of Things (IoT) devices, the overheads of virtual memory are becoming a critical performance bottleneck today. Virtual memory architectures designed for individual CPUs or even individual cores are in many cases struggling to scale up and scale out to today's systems which now increasingly include exotic hardware accelerators (such as GPUs, FPGAs, or DSPs) and emerging memory technologies (such as non-volatile memory), and which run increasingly intensive workloads (such as virtualized and/or "big data" applications). As such, many of the fundamental abstractions and implementation approaches for virtual memory are being augmented, extended, or entirely rebuilt in order to ensure that virtual memory remains viable and performant in the years to come.

Networks on Chips

Author: Giovanni De Micheli
Publisher: Elsevier
ISBN: 9780080473567
Format: PDF, Kindle
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The design of today's semiconductor chips for various applications, such as telecommunications, poses various challenges due to the complexity of these systems. These highly complex systems-on-chips demand new approaches to connect and manage the communication between on-chip processing and storage components and networks on chips (NoCs) provide a powerful solution. This book is the first to provide a unified overview of NoC technology. It includes in-depth analysis of all the on-chip communication challenges, from physical wiring implementation up to software architecture, and a complete classification of their various Network-on-Chip approaches and solutions. * Leading-edge research from world-renowned experts in academia and industry with state-of-the-art technology implementations/trends * An integrated presentation not currently available in any other book * A thorough introduction to current design methodologies and chips designed with NoCs

Multi Core Cache Hierarchies

Author: Rajeev Balasubramonian
Publisher: Morgan & Claypool Publishers
ISBN: 9781598297539
Format: PDF, ePub
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A key determinant of overall system performance and power dissipation is the cache hierarchy since access to off-chip memory consumes many more cycles and energy than on-chip accesses. In addition, multi-core processors are expected to place ever higher bandwidth demands on the memory system. All these issues make it important to avoid off-chip memory access by improving the efficiency of the on-chip cache. Future multi-core processors will have many large cache banks connected by a network and shared by many cores. Hence, many important problems must be solved: cache resources must be allocated across many cores, data must be placed in cache banks that are near the accessing core, and the most important data must be identified for retention. Finally, difficulties in scaling existing technologies require adapting to and exploiting new technology constraints.The book attempts a synthesis of recent cache research that has focused on innovations for multi-core processors. It is an excellent starting point for early-stage graduate students, researchers, and practitioners who wish to understand the landscape of recent cache research.The book is suitable as a reference for advanced computer architecture classes as well as for experienced researchers and VLSI engineers.Table of Contents: Basic Elements of Large Cache Design / Organizing Data in CMP Last Level Caches / Policies Impacting Cache Hit Rates / Interconnection Networks within Large Caches / Technology / Concluding Remarks

Architecture of Computing Systems ARCS 2017

Author: Jens Knoop
Publisher: Springer
ISBN: 3319549995
Format: PDF, Mobi
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This book constitutes the proceedings of the 30th International Conference on Architecture of Computing Systems, ARCS 2017, held in Vienna, Austria, in April 2017. The 19 full papers presented in this volume were carefully reviewed and selected from 42 submissions. They were organized in topical sections entitled: resilience; accelerators; performance; memory systems; parallelism and many-core; scheduling; power/energy.

Shared memory Synchronization

Author: Michael L. Scott
Publisher:
ISBN: 9781608459568
Format: PDF, ePub, Mobi
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Since the advent of time sharing in the 1960s, designers of concurrent and parallel systems have needed to synchronize the activities of threads of control that share data structures in memory. In recent years, the study of synchronization has gained new urgency with the proliferation of multicore processors, on which even relatively simple user-level programs must frequently run in parallel. This lecture offers a comprehensive survey of shared-memory synchronization, with an emphasis on "systems-level" issues. It includes sufficient coverage of architectural details to understand correctness and performance on modern multicore machines, and sufficient coverage of higher-level issues to understand how synchronization is embedded in modern programming languages. The primary intended audience is "systems programmers"-the authors of operating systems, library packages, language run-time systems, concurrent data structures, and server and utility programs. Much of the discussion should also be of interest to application programmers who want to make good use of the synchronization mechanisms available to them, and to computer architects who want to understand the ramifications of their design decisions on systems-level code. Table of Contents: Introduction / Architectural Background / Essential Theory / Practical Spin Locks / Busy-wait Synchronization with Conditions / Read-mostly Atomicity / Synchronization and Scheduling / Nonblocking Algorithms / Transactional Memory / Author's Biography

Automated Technology for Verification and Analysis

Author: Franck Cassez
Publisher: Springer
ISBN: 3319119362
Format: PDF, Kindle
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This book constitutes the proceedings of the 12th International Symposium on Automated Technology for Verification and Analysis, ATVA 2014, held in Sydney, Australia, in November 2014. The 29 revised papers presented in this volume were carefully reviewed and selected from 76 submissions. They show current research on theoretical and practical aspects of automated analysis, verification and synthesis by providing an international forum for interaction among the researchers in academia and industry.