This research project, started from October 2006, is supported by JST (Japanese Science and Technology) as a CREST (Core Research for Evolutional Science and Technology) program in the research area of technology innovation and integration for information systems with ultra low power.
The objective of this research is to develop and innovative power control method through tight collaboration and co-optimization of circuit-level design, architecture/compiler, and system software. The goal of this research is to reduce power consumption by two orders of magnitude.

Multi-core processors are becoming more popular today and heading towards many-core processors as the technology continues to shrink. Future System-on-Chips (SoCs) are also said to adopt many-core architecture which is composed of many cores embedded with memory and accelerators on a chip. Although putting many cores on a chip sounds promising, they can have negative impacts on the overall performance or power consumption because of the increased latency and lack of communication bandwidth. Thus a new paradigm called Network-on-Chip (NoC), where each IP core is connected by not on-chip bus but routers using packet switching, has recently attracted attention in SoC design.
However, there are two major problems for the implementation of NoC-based many-core SoCs. First, the design optimization becomes much more difficult than before due to the large design space to explore. Second, the optimization is still insufficient in terms of the overall SoC architecture because they don't take the important characteristics of NoC into account.
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The power consumption of IT devices occupies about 5 percent of the Japan's total power consumption in 2006, and this is estimated to grow up to 25 percent in 2025 (predicted by the Ministry of Economy, Trade and Industry: Green IT Initiative). Thus the reduction of power consumption is an urgent issue.
There are two types of information systems; (1) back-end systems such as data centers, which do not have direct interaction with users and (2) front-end systems such as mobile laptops and desktop computers that compute in response to user requests. Front-end systems are often idle and not always processing so if they are always turned on, the percentage of time when they are wasting power would be much higher than that of back-end systems. The number of front-end systems is drastically increasing today and they tend to be embedded with high performance/power-consuming processors and network interfaces like back-end systems recently. Therefore, the increase of these wasted power becomes a serious problem.
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Today, our life depends on computer systems in innumerable aspects, ranging from children's games to national security. People's daily life cannot exist without computers in home, amusement facilities, transportation, communication networks, industrial activities, financial and insurance services, medical services, art and cultural activities, commercial activities, agricultural management, government administration, and so on. Furthermore, we tend to be unaware of this fact.

Under these circumstances, dependability of a computer is of the most importance. If a failure occured in computer systems which our advanced information society fully depends on, tremendous human lives could be lost, or an economic disaster could occur. There is even a possibility of a war.
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