Arithmetic Intensity and the Roofline Model: Why LLM Generation Is Memory-Bound and Prefill Is Compute-Bound
Arithmetic Intensity and the Roofline Model in Large Language Models: Why Generation Is Memory-Bound and Prefill Is Compute-Bound Every optimization in modern large language model (LLM) serving exists to solve a single hardware reality: running a Transformer model is not one computational problem, but two completely distinct workloads operating on opposite sides of a physical performance barrier. When an LLM processes a prompt during the prefill phase, it saturates modern GPU Tensor Cores, ope



















