Brute-force indices are usually arithmetic bound (e.g., GEMM).
Cell-probe based indices are usually memory bandwidth bound (IVF, LSH bucketing, etc).
Graph-based indices are usually memory latency bound (traversing linked lists / graph data structures).
(I wrote the GPU half of Faiss and work with the people who wrote this paper).
(I wrote the GPU half of Faiss and work with the people who wrote this paper).