Rust Profiling with Samply

Profile Rust binaries to find CPU bottlenecks using samply.

Quick Start

# 1. Ensure profiling profile exists in Cargo.toml (see reference.md)
# 2. Build with debug symbols
cargo build --profile profiling

# 3. Profile (opens Firefox Profiler UI)
samply record ./target/profiling/<binary> [args...]

# 4. Or save for CLI analysis
samply record --save-only -o profile.json ./target/profiling/<binary>
python3 ~/.claude/skills/rust-profiling/scripts/analyze_profile.py profile.json

Skill Files

| File | Purpose | |------|---------| | reference.md | Cargo.toml setup, samply options, troubleshooting | | examples.md | Common profiling scenarios and analysis patterns | | scripts/analyze_profile.py | CLI tool to analyze saved profile.json files |

When to Use

• Performance is slower than expected
• Before optimizing (measure first!)
• After optimization (verify improvement)
• Investigating CPU-bound operations

What to Look For

| Pattern | Meaning | Action | |---------|---------|--------| | High self-time | Function itself is slow | Direct optimization target | | High total-time | Called often or slow callees | Check call frequency | | malloc/alloc in hot path | Allocation overhead | Pool, arena, or stack allocate | | pthread_mutex/parking_lot | Lock contention | Reduce lock scope or use lock-free |