power consumption reduction;interconnection networks;link width adjustment;multiprocessor systems;network bandwidth;

The huge increase both in size and complexity of high-end multiprocessor systems has triggered their power consumption. Air or liquid cooling systems are needed, which, in turn, increases power consumption. Another important percentage of the consumption is due to the interconnection network. In this paper, we propose a mechanism that dynamically reduces the available network bandwidth when traffic becomes low. Unlike other approaches that completely switch links off when they are not fully utilized, our mechanism is based on reducing their bandwidth by narrowing their width. As the topology of the network is not modified, the same routing algorithm can be used regardless of the power consumption level, which simplifies the router design. By using this strategy, the consumption may be strongly reduced. In fact, the lower bound of this reduction is a design parameter of the mechanism. The price to pay is an increase in the message latency with low network loads