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Votes

0

Found in

2021.3.2f1

2022.2.0a13

Issue ID

UUM-1206

Regression

Yes

Excessive GPU usage in Play mode despite limiting FPS via scripts

-

How to reproduce:
1. Open the user's attached "RefreshBug" project
2. Enter Play mode
3. Open Task Manager or any other system monitor
4. Observe Unity's GPU usage

Expected result: GPU usage is relatively low (0-25%)
Actual result: GPU usage is very high (35-60%) despite FPS being limited to the monitor's refresh rate

Reproducible with: 2021.2.0a2, 2021.3.2f1, 2022.1.0f1, 2022.2.0a13
Not reproducible with: 2019.4.39f1, 2020.3.34f1, 2021.2.0a1

Note: During testing, NVidia Geforce GTX 1650 Ti produced 20% GPU usage before the regression and 50% after the regression

  1. Resolution Note:

    This is a documented behaviour: https://docs.unity3d.com/ScriptReference/Application-targetFrameRate.html

    <...> On all other platforms (Mac editor included), Unity ignores the value of targetFrameRate if you set vSyncCount. When you use vSyncCount, Unity calculates the target frame rate by dividing the platform's default target frame rate by the value of vSyncCount. For example, if the platform's default render rate is 60 fps and vSyncCount is 2, Unity tries to render the game at 30 frames per second. <...>

    High FPS is expected to in turn cause high CPU usage.

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