Parameter based tuning model for optimizing performance on GPU

Abstract

Recently, the graphic processing units (GPUs) are becoming increasingly popular for the high performance computing applications. Although the GPUs provide high peak performance, exploiting the full performance potential for application programs, however, leaves a challenging task to the programmers. When launching a parallel kernel of an application on the GPU, the programmer needs to carefully select the number of blocks (grid size) and the number of threads per block (block size). These values determine the degree of SIMD parallelism and the multithreading, and greatly influence the performance. With a huge range of possible combinations of these values, choosing the right grid size and the block size is not straightforward. In this paper, we propose a mathematical model for tuning the grid size and the block size based on the GPU architecture parameters. Using our model we first calculate a small set of candidate grid size and block size values, then search for the optimal values out of the candidate values through experiments. Our approach significantly reduces the potential search space instead of exhaustive search approaches in the previous research. Thus our approach can be practically applied to the real applications.