Performance impact of reconfigurable L1 cache on GPU devices

The newest GPU Kepler architecture offers a reconfigurable L1 cache per Streaming Multiprocessor with different cache size and cache associativity. Both these cache parameters affect the overall performance of cache intensive algorithms, i.e. the algorithms which intensively reuse the data. In this paper, we analyze the impact of different configurations of L1 cache on execution of matrix multiplication algorithm for different problem sizes. The basis of our research is the existing theoretical analysis of performance drawbacks which appear for matrix multiplication while executed on multicore CPU. We perform series of experiments to analyze the matrix multiplication execution behavior on GPU and its set associative L1 and L2 cache memory with three different configurations: cache size of 16KB, 32KB and 48KB with appropriate set associativity of 4 and 6, respectively. The results show that only L2 cache impacts the algorithm´s overall performance, particularly the L2 capacity and set associativity. However, the configuration of the L1 cache with 48KB and 6-way set associativity slightly reduces these performance drawbacks, compared to other configurations of L1 with 32KB and 16KB using 4-way cache set associativity, due to greater set associativity.