Profiling a GPU database implementation: a holistic view of GPU resource utilization on TPC-H queries

Abstract

General Purpose computing on Graphics Processing Units (GPGPU) has become an increasingly popular option for accelerating database queries. However, GPUs are not well-suited for all types of queries as data transfer costs can often dominate query execution. We develop a methodology for quantifying how well databases utilize GPU architectures using proprietary profiling tools. By aggregating various profiling metrics, we break down the different aspects that comprise occupancy on the GPU across the runtime of query execution. We show that for the Alenka GPU database, only a small minority of execution time, roughly 5% is spent on the GPU. We further show that even on queries with seemingly good performance, a large portion of the achieved occupancy can actually be attributed to stalls and scalar instructions.