Developer Notes

On DX11 it's expected that CPU driver bubbles will manifest in a suspiciously large value on some section of a profile GPU. Not much we can do about it until we are on DX12.

Description

HZB Setup Mips in the GPU Visualizer seems to be taking considerable ms in 4.12 and 4.13 compared to 4.11.2.

This seems to mostly affect editor/PIE GPU Visualization but looks like it should when in Standalone Game.

Editor
4.11.2 - HZB Setup Mips was 0.02
4.12.5 - HZB Setup Mips was 2.85
4.13 Dev Rendering - HZB SetupMips was 2.82

Standalone Game
4.11.2 - HZB SetupMips was 0.02
4.12.5 - HZB SetupMips was 0.08
4.13 Dev Rendering - HZB SetupMips was 1.36

In 4.12 and 4.13 if r.HZBOcclusion was enabled then the PIE/Editor would have the HZBSetupMips register as 0.02ms.

Steps to Reproduce

1. Open UE4
2. Setup some actors that can be occluded (attached image for my test setup)
3. Open the GPU Visualizer by holding Ctrl + Shift + ,
4. Look at the HZB SetupMips

Regression: YES

Expected: HZB SetupMips shouldn't have this high cost.

Results: HZB SetupMips is using additional ms time when it shouldn't.

Have Comments or More Details?

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Fixed
ComponentRendering
Affects Versions4.124.13
Target Fix4.18
Fix Commit3523534
Main Commit3608256
Release Commit3643070
CreatedJul 19, 2016
ResolvedJul 6, 2017
UpdatedApr 27, 2018