Matt Godbolt is the creator and primary maintainer of Compiler Explorer. A C++ developer based in Chicago, he works at Hudson River Trading and is one half of the Two's Complement podcast. His career has been a steady journey deeper into the machine: from writing rendering engines for video games to years of low-latency trading systems. His recent Advent of Compiler Optimisations series explored things compilers do that feel like magic.
When not hacking on Compiler Explorer, Matt likes to write emulators for the computers he grew up on, the ZX Spectrum, BBC Micro and Sega Master System.
Every low-latency C++ developer measures time - but how many truly understand what they're measuring? This talk takes a deep dive into the machinery behind performance measurement on modern Linux systems: from std::chrono::steady_clock::now() through the vdso, down to rdtsc and hardware performance counters, and back up through the layers of abstraction that can silently distort your results. Along the way, we'll explore the subtle pitfalls that make microbenchmarking so treacherous: compilers that optimise away the code you're trying to measure, branch predictors that learn your benchmark's patterns, pipelining effects that make sequential measurements misleading, and the surprisingly complex question of […]