Low-Power and High-Performance Design of OpenGL ES 2.0 Graphics Processing Unit for Mobile Applications

Low-Power High-Speed graphics processing unit (GPU) is one of the key hardware components in modern mobile devices such as smart phones. This paper presents several methods to improve the execution performance and reduce the power of a previously designed programmable GPU for OpenGL ES 2.0 specification. The GPU has a vectored and single-instruction-multiple-data (SIMD) architecture that can execute a maximum of four concurrent scalar operations, and supports the functions of swizzle and write mask. Besides, a special function unit (SFU) is included in the GPU to compute complicate arithmetic functions such as reciprocal square-root, logarithm and exponential. As per performance improvements, hazard control and data forwarding mechanism are added in the GPU architecture to reduce the stalls caused by data dependency. Furthermore, the execution pipeline is re-designed so that the number of execution pipeline stages is reduced with more balanced delay in each stage. For power reduction, this paper presents several methods that disenable unused execution and/or memory units. The memory units are also partitioned into several banks so that only a small portion of memory is active during memory access. According to the experimental results, the new GPU designs have significant improvement in performance and power compared with the prior design.