A Dual-Mode Unified Shader with Frame-Based Dynamic Precision Adjustment for Mobile GPUs

In order to extend the life for battery driven mobile devices and maintain image quality, this paper presents a dual-mode unified shader for mobile GPUs, which consists of floating-point and fixed-point SIMD shader, for high quality or energy-saving rendering. Furthermore, in order to increase the image quality in fixed-point rendering, this paper proposes a frame-based dynamic precision adjustment scheme to select appropriate precision for different 3D scenes. The proposed design has following characteristics: I) high quality rendering with floating-point and fixed-point rendering for energy saving, II) a frame-based dynamic precision adjustment scheme to select appropriate precision for given scene, III) a workload-based scene change detection mechanism to re-select precision in time. Furthermore, this paper presents side by side comparison on performance, power and image quality between floating-point and fixed-point rendering in real world 3D games. The results of proposed shader in real world 3D games have 48.6% reduction in dynamic power and 33% faster in thread execution for a shader under energy saving mode in average. Furthermore, the rendered image qualities under proposed dynamic precision are insensitive to human eyes and the PSNR outperform related work for 2.37% in average. This reveals a way to use conventional fixed-point with dynamic precision to implement low power unified shader with quality rendering for such power limited devices.