Documentation

hprof is suitable only for getting rough measurements of "systems", rather than fine-tuned profiling data. Consider using perf, SystemTap, DTrace, VTune, etc for more detailed profiling.

Hierarchical profiling is based on the observation that games are typically organized into a "tree" of behavior. You have an AI system that does path planning, making tactical decisions, etc. You have a physics system that does collision detection, rigid body dynamics, etc. A tree might look like:

• Physics
  • Collision detection
    • Broad phase
    • Narrow phase
  • Fluid simulation
  • Rigid body simulation
    • Collision resolution
    • Update positions
• AI
  • Path planning
  • Combat tactics
  • Build queue maintenance
• Render
  • Frustum culling
  • Draw call sorting
  • Draw call submission
  • GPU wait

A hierarchical profiler will annotate this tree with how much time each step took. This is an extension of timer-based profiling, where a timer is used to measure how long a block of code takes to execute. Rather than coding up a one-time timer, you merely call Profiler::enter("description of thing") and a new entry will be made in the profile tree.

The idea came from a 2002 article in Game Programming Gems 3, "Real-Time Hierarchical Profiling" by Greg Hjelstrom and Byon Garrabrant from Westwood Studios. They report having thousands of profile nodes active at a time.

This software is licensed under the Boost Software License. In short, you are free to use, modify, and redistribute in any form without attribution.

Timing information for main loop:
  setup - 1133523ns (6.725068%)
  physics - 2258292ns (13.3982%)
    collision - 1140731ns (50.512998%)
    update positions - 1108782ns (49.098257%)
  render - 13446767ns (79.778204%)
    cull - 1134725ns (8.438646%)
    gpu submit - 2197346ns (16.341073%)
    gpu wait - 10088879ns (75.028287%)