Understanding Why Your CPU is Slow: Hardware Performance Insights with PerfGo

The Problem

Go's pprof tells you where your CPU time is spent, but not why the CPU is slow. Is it cache misses? Branch mispredictions? These hardware-level performance characteristics are invisible to pprof but critical for optimisation.

The Solution

perf-go bridges this gap by leveraging Linux's perf tool and CPU Performance Monitoring Units (PMUs) to expose hardware performance counters for Go programs. It translates perf's low-level observations into pprof's familiar format, giving Go developers hardware insights without leaving their existing workflow.

What You'll Learn

In this talk, we'll: - Demonstrate the limitations of pprof for understanding performance bottlenecks - Show how perf-go exposes CPU cache behaviour, branch prediction, and memory access patterns - Walk through real benchmarks where we identify and fix cache-line contention issues - Explore how hardware counters can guide improvements that pprof alone wouldn't reveal

Target Audience

Go developers who want to optimise performance-critical code and understand the "why" behind their bottlenecks. Basic familiarity with profiling concepts helpful but not required.