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Ebook Computer organization and design (5th edition): Part 2

(BQ) The book uses a MIPS processor core to present the fundamentals of hardware technologies, assembly language, computer arithmetic, pipelining, memory hierarchies and I/O.Because an understanding of modern hardware is essential to achieving good performance and energy efficiency, this edition adds a new concrete example, Going Faster, used throughout the text to demonstrate extremely effective optimization techniques. | 5 Ideally one would desire an indefinitely large memory capacity such that any particular word would be immediately available. We are forced to recognize the possibility of constructing a hierarchy of memories, each of which has greater capacity than the preceding but which is less quickly accessible. Large and Fast: Exploiting Memory Hierarchy 374 5.1 Introduction 5.2 Memory Technologies 378 5.3 The Basics of Caches 383 5.4 Measuring and Improving Cache Performance 398 5.5 A. W. Burks, H. H. Goldstine, and J. von Neumann Preliminary Discussion of the Logical Design of an Electronic Computing Instrument, 1946 Dependable Memory Hierarchy 418 5.6 Virtual Machines 424 5.7 Virtual Memory 427 Computer Organization and Design. DOI: http://dx.doi.org/10.1016/B978-0-12-407726-3.00001-1 © 2013 Elsevier Inc. All rights reserved. 5.1 375 Introduction Speed Processor Size Cost ($/bit) Current technology Fastest Memory Smallest Highest SRAM Memory Slowest Memory DRAM Biggest Lowest Magnetic disk FIGURE 5.1 The basic structure of a memory hierarchy. By implementing the memory system as a hierarchy, the user has the illusion of a memory that is as large as the largest level of the hierarchy, but can be accessed as if it were all built from the fastest memory. Flash memory has replaced disks in many personal mobile devices, and may lead to a new level in the storage hierarchy for desktop and server computers; see Section 5.2. Just as accesses to books on the desk naturally exhibit locality, locality in programs arises from simple and natural program structures. For example, most programs contain loops, so instructions and data are likely to be accessed repeatedly, showing high amounts of temporal locality. Since instructions are normally accessed sequentially, programs also show high spatial locality. Accesses to data also exhibit a natural spatial locality. For example, sequential accesses to elements of an array or a record will .