Last time I wrote about profiling in Zig on Apple Silicon, I touched on PMU counter profiling. This time I decided to go further and create my own tool to fetch all available counters for Apple Silicon processors (M1, M2, and later). Brief explanation of PMU counters PMU (Performance Monitoring Unit) counters are hardware counters that track microarchitectural events inside the CPU, e.g. executed instructions, retired operations, branches, cache misses, and more.