Geometry Nodes: Performance regression and node tree evaluation difference #93969

New Issue

RoyTheKoi · 2021-12-11T18:22:13+01:00

RoyTheKoi commented

2021-12-11 18:22:13 +01:00

System Information
Operating system: macOS Big Sur 11.2.3
CPU: 2.3 GHz 8-Core Intel Core i9
Graphics card: AMD Radeon Pro 5500M 8 GB

Blender Version
Broken: 3.1 Alpha, 7b88a4a3ba, master, 2021-11-12
Worked: 3.1 Alpha, dffd032bc9, master, 2021-10-12

Short description of error
Evaluating the geometry node tree in the attached blend file is significantly slower in the Dec 11 build versus the Dec 10 build of 3.1 Alpha. The part of the tree that seems to account for the slowdown (mesh to curve and curve to mesh) is about 16-20x slower.

Not only is there a slow down, but some change in evaluation has meant that the output colour attribute is calculated differently as shown above. Adding an extra capture attribute node in the node group resolves this difference: Notice how the colours of the grid in the first (Dec 10) and third (Dec 11) screenshots match. Unfortunately adding this node this further impacts performance.

I'm not sure yet whether the evaluation difference is a regression, since it doesn't necessarily cause a negative effect here. All I know is that there is a definite difference between how Dec 10 and Dec 11 evaluates the same tree. The main issue is the significant slowdown.

Exact steps for others to reproduce the error
Geometry_Nodes_Slowdown.blend

Open the attached blend file in 3.1 Alpha Dec 10 and Dec 11 builds. The Dec 11 build evaluates much slower.
Also try muting the marked attribute capture node inside the node group --> this should cause a difference in the colours of the grid in the Dec 11 build, but have no effect in the Dec 10 build.

I have yet to pinpoint the exact cause for the slowdown so I'm unable to provide a simpler blend file or better steps to reproduce the issue at the moment.

**System Information** Operating system: macOS Big Sur 11.2.3 CPU: 2.3 GHz 8-Core Intel Core i9 Graphics card: AMD Radeon Pro 5500M 8 GB **Blender Version** Broken: 3.1 Alpha, 7b88a4a3ba7e, master, 2021-11-12 Worked: 3.1 Alpha, dffd032bc9b9, master, 2021-10-12 **Short description of error** Evaluating the geometry node tree in the attached blend file is significantly slower in the Dec 11 build versus the Dec 10 build of 3.1 Alpha. The part of the tree that seems to account for the slowdown (mesh to curve and curve to mesh) is about 16-20x slower. ![Dec_10_normal.png](https://archive.blender.org/developer/F12731027/Dec_10_normal.png) ![Dec_11_slowdown_and_evaluation_difference.png](https://archive.blender.org/developer/F12731038/Dec_11_slowdown_and_evaluation_difference.png) Not only is there a slow down, but some change in evaluation has meant that the output colour attribute is calculated differently as shown above. Adding an extra capture attribute node in the node group resolves this difference: Notice how the colours of the grid in the first (Dec 10) and third (Dec 11) screenshots match. Unfortunately adding this node this further impacts performance. ![Dec_11_difference_resolved_but_further_slowdown.png](https://archive.blender.org/developer/F12731053/Dec_11_difference_resolved_but_further_slowdown.png) I'm not sure yet whether the evaluation difference is a regression, since it doesn't necessarily cause a negative effect here. All I know is that there is a definite difference between how Dec 10 and Dec 11 evaluates the same tree. The main issue is the significant slowdown. **Exact steps for others to reproduce the error** [Geometry_Nodes_Slowdown.blend](https://archive.blender.org/developer/F12731089/Geometry_Nodes_Slowdown.blend) 1. Open the attached blend file in 3.1 Alpha Dec 10 and Dec 11 builds. The Dec 11 build evaluates much slower. 2. Also try muting the marked attribute capture node inside the node group --> this should cause a difference in the colours of the grid in the Dec 11 build, but have no effect in the Dec 10 build. I have yet to pinpoint the exact cause for the slowdown so I'm unable to provide a simpler blend file or better steps to reproduce the issue at the moment.

RoyTheKoi commented

2021-12-11 18:22:13 +01:00

Added subscriber: @RoyTheKoi