Daily Pathtracer 10: Update C#&GPU

Introduction and index of this series is here.

Short post; nothing new. Just wanted to update C#, Unity (C#+Burst) and GPU implementations with the larger scene and optimizations from previous blog posts. So that there’s some, ahem, unity between them again. Here they are, as github commits/PRs:

A note on C# Mono performance

As Miguel de Icaza noted on github and wrote on his blog in-depth, defaults in current Mono version (5.8/5.10) are not tuned for the best floating point performance. Read his blog for details; much better defaults should be shipping in later Mono versions! If nothing else, maybe this toy project will have been useful to gently nudge Mono into improving the defaults :)

Current performance numbers, in Mray/s

Implementation PC Mac
GPU 778 53.0
C++, SSE+SoA HitSpheres 187 41.8
C++, SoA HitSpheres 100 19.6
C#, Unity Burst 82.3 18.7
C#, .NET Core 53.0 13.1
C#, mono -O=float32 --llvm w/ MONO_INLINELIMIT=100 12.7
C#, mono -O=float32 --llvm 10.5
C#, mono -O=float32 6.0
C#, mono 5.5
  • PC is AMD ThreadRipper 1950X (3.4GHz, 16c/16t) with GeForce GTX 1080 Ti.
  • Mac is late-2013 MacBookPro (Core i7-4850HQ 2.3GHz, 4c/8t) with Intel Iris Pro.
  • Unity version 2018.1 beta 12 with Burst 0.2.3.
  • Mono version 5.8.1.
  • .NET Core version 2.1.4.

All code is on github at 10-impl-updates tag.

What’s next

I want to switch from a recursion/iteration oriented path tracer setup, into a stream/buffers oriented one, and see what happens. Just because! My blog, my rules :)