How to use profile guided optimization PGO

Enable Profile Guided Optimization in Rust by building with instrumentation, running your app to collect data, and rebuilding with the profile for faster execution.

Profile Guided Optimization (PGO) in Rust is enabled by building a profile, running your application to collect data, and then rebuilding with that profile. First, build your binary in profile mode to generate instrumentation:

rustup default nightly
cargo build --profile=perf

Next, run your application to generate profiling data in the target directory:

./target/perf/your_binary

Finally, rebuild your binary using the collected profile data for optimized code generation:

cargo build --profile=perf --release

Ensure your Cargo.toml defines the perf profile with codegen-backend and profile settings if not using the default nightly PGO support.

PGO helps your Rust program run faster by teaching the compiler how your code is actually used. You first build a special version that tracks usage, run your program to collect that data, and then rebuild the final version using those insights. It's like practicing a speech with a coach who notes your pauses, then delivering the final speech with perfect timing based on that feedback.