Performance, Profiling and Debugging — GPU Visualizer (Epic course, Michael Muir, Staff)

版本说明：UE 5.8 的 GPU Profiling 文档页（gpu-profiling-in-unreal-engine）与 4.27 旧版页均重定向到首页，未能抓取；此为 Epic 员工撰写、标注 UE 5.0 的课程页。

• GPU Visualizer identifies the cost of rendering passes; a scene snapshot, must be re-run after changes. Access: console ProfileGPU or Ctrl-Shift-, (comma). Shows time of each rendering pass.
• GPU crashes (D3D device lost / DXGI_ERROR_DEVICE_HUNG): CPU call stack doesn't point to the real cause. Run with -gpucrashdebugging or -d3ddebug (not together). Causes: out of memory, TDR timeout (default 2 s in Windows), engine bug, driver bug, OS bug, hardware.
• TDR & ray tracing: r.RayTracing.GlobalIllumination.RenderTileSize / r.RayTracing.Reflections.RenderTileSize render in tiles as separate command buffers.
• Engine bug A/B: -onethread -forcerhibypass; r.RDG.Debug=1; r.RDG.ImmediateMode=1 (meaningful call stacks, may be red herring); switch RHI DX11/DX12; toggle passes/features (Lumen, Nanite, ray tracing); hide objects.