Resumen
The chances to reach Exascale or Ultrascale Computing are strongly connected with the problem of the energy consumption for processing applications. For physical as well as economical reasons, the energy consumption has to be reduced significantly to make Ultrascale Computing possible. The research efforts towards energy-saving mechanisms of the hardware has already led to energy-aware hardware systems available today. However, hardware mechanisms can only obtain an energy reduction if software can exploit them such that energy-efficient computing actually results. In the software area, there also exists a multitude of research approaches towards energy saving. These research approaches and results are often isolated either on the system software level or the application organization level, reflecting the expertise of the corresponding research group. The challenge of reducing the energy consumption dramatically to make Ultrascale Computing possible are so ambitions that a concerted action combining all these software levels and research efforts seems reasonable. In this article, we demonstrate the current research efforts and results related to energy in the diverse areas of software. Moreover, we conclude with open problems and questions concerning energy-related techniques with an emphasis on the application algorithmic side.