Which program transformations can reduce software energy consumption?

Research assistant Maria Bendix Mikkelsen made a research stay (under an STSM activity of CERCIRAS COST action), where prof. João Paulo Fernandes and his colleagues were hosting her. 

During the stay, Maria and researchers in the Green Software Lab collaborated to see what effect, if any, different program transformations and compiler optimizations have on the energy consumption of software. Since these transformations can reduce time consumption and optimize data structures, they expect the energy consumption of the transformed programs to be reduced as well. It is crucial to study the energy consumption of software and ways to reduce it as the IT sector makes up a significant part of society’s total energy consumption.

Maria’s hopes that “this visit will help strengthen the collaboration between the University of Porto and Roskilde University” and that the visit “will be rewarding … as a new researcher in computer science” were completely fulfilled.

In particular, during experiments, it was observed a difference in average power dissipation between different tasks (programs) for both the GCC and Clang compilers. Also, a difference in average power dissipation between different compiler optimization flags for individual tasks was also observed. This suggests that time alone cannot be used to predict the precise average energy consumption of individual executables.

These results were presented and discussed at a PhD Seminar at Roskilde University and a research paper at an international conference is planned.