Ampere PMU Profiler: A Guide to Microarchitecture Profiling

Executive Summary The Ampere® PMU Profiler (APP) is a Python-based tool designed to provide deep insight into the microarchitectural behavior of applications running on Ampere CPUs (e.g., Ampere® Altra® and AmpereOne®). Unlike standard profilers that identify where time is spent (e.g., which functions consume CPU time), the PMU Profiler explains why time is being spent by measuring low-level hardware events associated with the CPU pipeline and execution behavior. A key outcome of APP is that it enables performance engineers to move from coarse symptoms to actionable causes.