Multi-Core Processors or Dual-Core Processors
[
attachment=31469]
INTRODUCTION
Multi-core processors represent a major evolution in computing technology.
What are multi-core processors?
Integrated circuit (IC) chips containing more than one identical physical processor(core) in same IC package. OS perceives each core as a discrete processor. Each core has its own complete set of resources, and may share the on-die cache layers.
Why Multi-core Processor is needed?
• Difficult to make single-core
clock frequencies even higher
• Deeply pipelined circuits:
– heat problems
– speed of light problems
– difficult design and verification
– large design teams necessary
– server farms need expensive
air-conditioning
• Many new applications are multithreaded
• General trend in computer architecture (shift towards more parallelism
LITERATURE REVIEW
The trend of increasing a processor’s speed to get a boost in performance is a way of the past. Multi-core processors are the new direction manufacturers are focusing on. Using multiple cores on a single chip is advantageous in raw processing power, but nothing comes for free.
With additional cores, power consumption and heat dissipation become a concern and must be simulated before lay-out to determine the best floorplan which distributes heat across the chip, while being careful not to form any hot spots. Distributed and shared caches on the chip must adhere to coherence protocols to make sure that when a core reads from memory it is reading the current piece of data and not a value that has been updated by a different core. With multi-core processors come issues that were previously unforeseen. How will multiple cores communicate? Should all cores be homogenous, or are highly specialized cores more efficient? And most importantly, will programmers be able to write multithreaded code that can run across multiple cores?
Moore’s Law
One of the guiding principles of computer architecture is known as Moore‟s Law. In 1965 Gordon Moore stated that the number of transistors on a chip will roughly double each year (he later refined this, in 1975, to every two years). What is often quoted as Moore‟s Law is Dave House‟s revi-sion that computer performance will double every 18 months. [20] The graph in Figure 1 plots many of the early microprocessors briefly discussed in Section 1.1 against the number of transistors per chip.
CONCLUSION
In the next years the trend will go to multi-core processors more and more. The main reason is that they are faster than single-core processors and they can be still improved, but with added new problems. But in future there will be still some applications for single-core processors because not every system needs a fast processor.
Before multi-core processors the performance increase from generation to generation was easy to see, an increase in frequency. This model broke when the high frequencies caused processors to run at speeds that caused increased power consumption and heat dissipation at detrimental levels. Adding multiple cores within a processor gave the solution of running at lower frequencies, but added interesting new problems.
Multi-core processors are architected to adhere to reasonable power consumption, heat dissipation, and cache coherence protocols. However, many issues remain unsolved. In order to use a multi-core processor at full capacity the applications run on the system must be multithreaded. There are relatively few applications (and more importantly few programmers with the know-how) written with any level of parallelism. The memory systems and interconnection net-works also need improvement. And finally, it is still unclear whether homogeneous or heterogeneous cores are more efficient.