Energy-precision tradeoffs in mobile Graphics Processing Units

Abstract

In mobile devices, limiting the Graphics Processing Unitpsilas (GPUpsilas) energy usage is of great importance to extending battery life. This paper focuses on the first stage of the graphics processor pipeline - the vertex transformation stage - and introduces an approach to lowering its switching activity by reducing the precision of arithmetic operations. As a result, the approach enables a tradeoff between energy efficiency and the quality of the rendered image. This paper makes the following specific contributions: 1) a transition-based energy model for quantifying energy consumed as a function of arithmetic precision, and 2) detailed simulation results on several real-world graphics applications to evaluate the tradeoff between energy and precision. In most examples, over 23% of the energy can be saved by lowering arithmetic precision while still maintaining a faithful reproduction of the full-precision image. Pushing the idea further, over 36% energy can be saved by further lowering the precision while preserving acceptable result accuracy. We assert that this represents a significant energy savings that warrants further investigation and extension of our approach to the remaining stages of the graphics processor pipeline.