FPGA-based acceleration of neural network for ranking in web search engine with a streaming architecture

Web search engine companies are intensively running learning to rank algorithms to improve the search relevance. Neural network (NN)-based approaches, such as LambdaRank, can significantly increase the ranking quality. While, their training is very slow on a single computer and inherent coarse-grained parallelism could be hardly utilized by computer clusters. Thus an efficient implementation is necessary to timely generate acceptable NN models on frequently updated training datasets. This paper presents our work in accelerator. A SIMD streaming architecture is proposed to i) efficiently map the query-level NN computation and data structure to FPGA, ii) fully exploit the inherent fine-grained parallelism, and iii) provide scalability to large scale datasets. The accelerator shows up to 17.9X speedup over the software implementation on datasets from a commercial search engine.