Multi-core processors - An overview <s> Evolution of Multi-core processor <s> A simple observation, made over 30 years ago, on the growth in the number of devices per silicon die has become the central driving force of one of the most dynamic of the world's industries. Because of the accuracy with which Moore's Law has predicted past growth in IC complexity, it is viewed as a reliable method of calculating future trends as well, setting the pace of innovation, and defining the rules and the very nature of competition. And since the semiconductor portion of electronic consumer products keeps growing by leaps and bounds, the Law has aroused in users and consumers an expectation of a continuous stream of faster, better, and cheaper high-technology products. Even the policy implications of Moore's Law are significant: it is used as the baseline assumption in the industry's strategic road map for the next decade and a half. <s> BIB001 </s> Multi-core processors - An overview <s> Evolution of Multi-core processor <s> Power consumption is a major factor that limits the performance of computers. We survey the “state of the art” in techniques that reduce the total power consumed by a microprocessor system over time. These techniques are applied at various levels ranging from circuits to architectures, architectures to system software, and system software to applications. They also include holistic approaches that will become more important over the next decade. We conclude that power management is a multifaceted discipline that is continually expanding with new techniques being developed at every level. These techniques may eventually allow computers to break through the “power wall” and achieve unprecedented levels of performance, versatility, and reliability. Yet it remains too early to tell which techniques will ultimately solve the power problem. <s> BIB002 </s> Multi-core processors - An overview <s> Evolution of Multi-core processor <s> In the past, processor design trends were dominated by increasingly complex feature sets, higher clock speeds, growing thermal envelopes and increasing power dissipation. Recently, clock speeds have tapered and thermal and power dissipation envelopes have remained flat. However, the demand for increasing performance continues which has fueled the move to integrated multiple processor (multi-core) designs. This paper discusses this trend towards multi-core processor designs, the design challenges that accompany it and a view of the research required to support it. <s> BIB003 </s> Multi-core processors - An overview <s> Evolution of Multi-core processor <s> This paper presents the many-core architecture, with hundreds to thousands of small cores, to deliver unprecedented compute performance in an affordable power envelope. We discuss fine grain power management, memory bandwidth, on die networks, and system resiliency for the many-core system. <s> BIB004 </s> Multi-core processors - An overview <s> Evolution of Multi-core processor <s> Continuous effort to achieve higher performance without driving up the power consumption and thermal effects has led the researchers to look for alternative architectures for microprocessors. Like the parallel processing which is extensively used in today's all microprocessors, multi-core architecture which combines several independent microprocessor cores in a single die has currently become very popular in most high performance intergrated circuits. Although multi-core processor offers excellent instruction execution speed with reduced power consumption, optimizing performance of individual processors and then incorporating them by interconnection on a single chip is a non-trivial task. This paper investigates the leading challenges associated with current high performance multi-core processor in terms of interfacing different cores, design automation and verification, software adaptability. <s> BIB005 </s> Multi-core processors - An overview <s> Evolution of Multi-core processor <s> Multicore and multithreaded CPUs have become the new approach to obtaining increases in CPU performance. Numeric applications mostly benefit from a large number of computationally powerful cores. Servers typically benefit more if chip circuitry is used for maximizing throughput via multiple threads per core. <s> BIB006 </s> Multi-core processors - An overview <s> Evolution of Multi-core processor <s> With modern techniques that allow billions of transistors on a chip, microprocessor design is going to a world of multicore. A cluster of multicores will be commonly used as an efficient computational platform for high performance computing in the near future. Correspondingly, the resource providers, who share their computing elements and storage with customers, will also upgrade their machines to the multicore architecture. At the same time, the dominating resource sharing platforms, in the form of compute Grids, are facing a grand challenge from Cloud computing. With an easy interface, high-level services, and on-demand provision of compute resources, compute Clouds are attracting more users to join their realm. Upcoming Cloud environments will be primarily built on top of multicore technologies. However, to fully exploit the computational capacity and the other advantages of multicores, a lot of novel techniques must be proposed and investigated. This paper serves as an overview for multicore technologies in the context of Cloud computing. This paper firstly introduces multicore technologies and the Cloud computing concept. Then it investigates various open research issues in the context of multicore Cloud computing, for example, how to efficiently employ multicore techniques for Cloud computing, how to achieve the high performance of multicore for high performance applications in the Cloud environments. Several examples and discussion are presented. <s> BIB007
Driven by a performance hungry market, microprocessors have always been designed keeping performance and cost in mind. Gordon Moore, founder of Intel Corporation predicted that the number of transistors on a chip will double once in every 18 months to meet this ever growing demand which is popularly known as Moore's Law in the semiconductor industry BIB003 BIB001 BIB006 . Advanced chip fabrication technology alongside with integrated circuit processing technology offers increasing integration density which has made it possible to integrate one billion transistors on a chip to improve performance BIB007  . However, the performance increase by micro-architecture governed by Pollack's rule is roughly proportional to square root of increase in complexity BIB004 . This would mean that doubling the logic on a processor core would only improve the performance by 40%. With advanced chip fabrication techniques comes along another major bottleneck, power dissipation issue. Studies have shown that transistor leakage current increases as the chip size shrinks further and further which increases static power dissipation to large values as shown in Figure 1 BIB004 BIB005 . One alternate means of improving performance is to increase the frequency of operation which enables faster execution of programs  BIB003 . However the frequency is again limited to 4GHz currently as any increase beyond this frequency increases power dissipation again BIB003 . "Battery life and system cost constraints drive the design team to consider power over performance in such a scenario"  . Power consumption has increased to such high levels that traditional air-cooled microprocessor server boxes may require budgets for liquid-cooling or refrigeration hardware  . Designers eventually hit what is referred to as the power wall, the limit on the amount of power a microprocessor could dissipate  . BIB002 Semiconductor industry once driven by performance being the major design objective, is today being driven by other important considerations such chip fabrication costs, fault tolerance, power efficiency and heat dissipation BIB006 . This led to the development of multi-core processors which have been effective in addressing these challenges.