Per-call Energy Saving Strategies in All-to-All Communications

With the increase in the peak performance of modern computing platforms, their energy consumption grows as well, which may lead to overwhelming operating costs and failure rates. Techniques, such as Dynamic Voltage and Frequency Scaling (called DVFS) and CPU Clock Modulation (called throttling) are often used to reduce the power consumption of the compute nodes. However, these techniques should be used judiciously during the application execution to avoid significant performance losses. In this work, two implementations of the all-to-all collective operations are studied as to their augmentation with energy saving strategies on the per-call basis. Experiments were performed on the OSU MPI benchmarks as well as on a few real-world problems from the CPMD and NAS suits, in which energy consumption was reduced by up to 10% and 15.7%, respectively, with little performance degradation.