The challenges of multi-core technology

Keywords: multi-core technology  concurrent programming challenges  programming languages 

Multicore processors—basically processors with more than one core—are becoming mainstream. Today, even desktops are having two or four cores. This trend is picking up and will only accelerate in the coming years. This article looks at the drivers for multi-core, the challenges posed to the software community by the emergence of multi-core technologies, the different options available in software and how the software community is likely to react to the challenges.

In recent times, there has been a perceptible slow down in Moore's Law, which says that the number of transistors will double in every 18 months. Well, transistor count is doubling, but performance is not keeping in pace. Performance kept pace until 2002 due to technologies like pipelining, caching and superscalar designs. After that, however, the gap has started becoming visible as the returns from these technologies began to yield diminishing returns.

For example, between 1993 and 1999, CPU speeds increased ten-fold. The first 1GHz CPU was released in 2000. In the last nine years, it has gone up to only 3.3GHz, a growth that is considerably slower than the previous six years.

Power is another driver. Power consumed is related to frequency, and increasing frequency makes a huge drain on the power. The challenges of designing appropriate heat sinks, airflows in servers and desktops become pronounced as frequency increases. Another impact is the high operating costs of data centres due to higher costs in air conditioning and cooling systems and there is pressure to reduce operating expenditures of enterprises and service providers. This is referred to as "power wall."

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