POWAR: Power-Aware Routing in HPC Networks with On/Off Links.

In order to save energy in HPC interconnection networks, one usual proposal is to switch idle links into a low-power mode after a certain time without any transmission, as IEEE Energy Efficient Ethernet standard proposes. Extending the low-power mode mechanism, we propose POWer-Aware Routing (POWAR), a simple power-aware routing and selection function for fat-tree and torus networks. POWAR adapts the amount of network links that can be used, taking into account the network load, and obtaining great energy savings in the network (55%--65%) and the entire system (9%--10%) with negligible performance overhead.