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PerformanceTest.md

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Performance Test

The performance test application contains a couple of simple scenes to test performance of Jolt Physics. It will output the results to the TTY in CSV format.

Commandline options

  • -s=[scene]: This allows you to select a scene, [scene] can be;
    • Ragdoll: A scene with 16 piles of 10 ragdolls (3680 bodies) with motors active dropping on a level section.
    • RagdollSinglePile: A single pile of 160 ragdolls (3680 bodies) with motors active dropping on a level section.
    • ConvexVsMesh: A simpler scene of 484 convex shapes (sphere, box, convex hull, capsule) falling on a 2000 triangle mesh.
    • Pyramid: A pyramid of 1240 boxes stacked on top of each other to profile large island splitting.
  • -i=[iterations]: Number of physics steps before the test finishes.
  • -q=[quality]: This limits the motion quality types that the test will run on. By default it will test both. [quality] can be:
    • Discrete: Discrete collision detection
    • LinearCast: Linear cast continous collision detection
  • -t=[num]: This sets the amount of threads the test will run on. By default it will test 1 .. number of virtual processors. Can be 'max' to run on as many thread as the CPU has.
  • -no_sleep: Disable sleeping.
  • -p: Outputs a profile snapshot every 100 iterations
  • -r: Outputs a performance_test_[tag].jor file that contains a recording to be played back with JoltViewer
  • -f: Outputs the time taken per frame to per_frame_[tag].csv
  • -h: Displays a help text
  • -rs: Record the simulation state in state_[tag].bin.
  • -vs: Validate the recorded simulation state from state_[tag].bin. This will after every simulation step check that the state is the same as the recorded state and trigger a breakpoint if this is not the case. This is used to validate cross platform determinism.
  • -repeat=[num]: Repeats all tests num times.
  • -validate_hash=[hash]: Will validate that the hash of the simulation matches the supplied hash. Program terminates with return code 1 if it doesn't. Can be used to automatically validate determinism.

Output

  • Motion Quality: Shows the motion quality for the test.
  • Thread Count: The amount of threads used for the test.
  • Steps / Second: Average amount of physics steps / second over the entire duration of the test.
  • Hash: A hash of all positions and rotations of the bodies at the end of the test. Can be used to verify that the test was deterministic.

Results

If you're interested in how Jolt scales with multiple CPUs and compares to other physics engines, take a look at this document.