hotpath-rs dev blog

Notes on Rust performance, profiling techniques, and development updates from building hotpath-rs by Paweł Urbanek.

Instrumentation vs sampling & flame graphs: picking the right Rust profiler

December 17, 2025

A comparison of hotpath with established sampling profilers such as perf, flamegraph, and samply. We walk through three common Rust performance profiling scenarios - CPU-bound code, blocking I/O, and async I/O - to show how the runtime metrics from sampling profilers differ from hotpath instrumentation (in some cases, the results are completely different).

Lessons Learned Building High-Performance Rust Profiler

May 12, 2026

The Rust performance book features over a dozen different profiling tools. So I’m not sure if the world needed a new Rust profiler. Still, I spent the last 6+ months building hotpath-rs. In this post, I’ll describe the design decisions behind the library and share a few performance challenges I encountered while working on it. We’ll go deep into the low-level details: cache-line contention, async futures instrumentation, and decoding raw CPU traces back into Rust symbols.