Gpumixer: Performance-Driven Floating-Point Tuning For Gpu Scientific Applications

We present GPUMixer, a tool to perform mixed-precision floating-point tuning on scientific GPU applications. While precision tuning techniques are available, they are designed for serial programs and are accuracy-driven, i.e., they consider configurations that satisfy accuracy constraints, but these configurations may degrade performance. GPUMixer, in contrast, presents a performance-driven approach for tuning. We introduce a novel static analysis that finds Fast Imprecise Sets (FISets), sets of operations on low precision that minimize type conversions, which often yield performance speedups. To estimate the relative error introduced by GPU mixed-precision, we propose shadow computations analysis for GPUs, the first of this class for multi-threaded applications. GPUMixer obtains performance improvements of up to 46.4% of the ideal speedup in comparison to only 20.7% found by state-of-the-art methods.