ALook - adaptive lookup for GPGPU acceleration.

Associative memory in form of look-up table can decrease the energy consumption of GPGPU applications by exploiting data locality and reducing the number redundant computations. State of the art architectures utilize associative memory as static look-up tables. Static designs lack the ability to adapt to applications at runtime, limiting them to small segments of code with high redundancy. In this paper, we propose an adaptive look-up based approach, called ALook, which uses a dynamic update policy to maintain a set of recently used operations in associative memory. ALook updates with values computed by floating point units at runtime to adapt to the workload and matches the stored results to avoid recomputing similar operations. ALook utilizes a novel FPU architecture which accelerates GPU computation by parallelizing the operation lookup process. We test the efficiency of ALook on image processing, general purpose, and machine learning applications by integrating it beside FPUs in an AMD Southern Island GPU. Our evaluation shows that ALook provides 3.6X EDP (Energy Delay Product) and 32.8% performance speedup, compared to an unmodified GPU, for applications accepting less than 5% output error. The proposed ALook architecture improves the GPU performance by 2.0X as compared to state-of-the-art computational reuse methods for the same level of output error.