Benchmarking

A benchmark is a measurement system. It can report a precise number while measuring removed work, an unstable sample, or an uncontrolled machine. This talk argues you should trust a Go benchmark only after answering three questions: Is the compiler measuring real work? Is the sample stable enough? Is the difference large relative to the noise? We work through three layers. Compiler honesty covers dead-code elimination, sinks, constant folding, inlining, timer ordering, and the B.Loop construct that fixes the non-terminating-timer case. Statistical interpretation covers repeated samples, benchstat, coefficient of variation, run-count discipline, and the p-hacking traps that inflate false positives. Environment control covers both local machines and CI: Linux frequency and isolation controls, perflock, benchdiff, and the bare-metal runners that shared CI instances are not. ...

A Loose Cable That Broke Physics In 2006, a team of physicists began building the OPERA experiment — a 730-kilometer underground tunnel from CERN in Switzerland to Gran Sasso in Italy, designed to measure the speed of neutrinos. Five years of construction. Roughly 100 million euros. The most rigorous experimental physics on the planet. In September 2011, the results came back. Neutrinos were traveling faster than the speed of light. The team had just broken the laws of physics. ...

Measuring software performance reliably is remarkably difficult. It’s a specialized version of a more general problem: trying to find a signal in a world full of noise. A benchmark that reports a 5% improvement might just be measuring thermal throttling, noisy neighbors, or the phase of the moon. In this talk, we walk through the full stack of reliable performance measurement — from controlling your benchmarking environment (bare metal instances, CPU affinity, disabling SMT and dynamic frequency scaling) to designing benchmarks that are both representative and repeatable. We cover the statistical methods needed to interpret results correctly (hypothesis testing, change point detection) and show how to integrate continuous benchmarking into development workflows so regressions are caught before they reach production. ...