GPU subdivision: Bad performance with viewport statistics #96434

New Issue

Arie Leo · 2022-03-14T13:24:40+01:00

Arie Leo commented

2022-03-14 13:24:40 +01:00

System Information
Operating system: Windows-10-10.0.19044-SP0 64 Bits
Graphics card: NVIDIA GeForce GTX 1070/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 511.23

Blender Version
Broken: version: 3.2.0 Alpha, branch: master, commit date: 2022-03-14 00:08, hash: b959f603da.
Also broken in 3.1.0 Stable release.
Worked: None i can find.

I'm getting bad perfomance when using Modifier stacks and GPU Subdivision are enabled.
the video are recorded on 3.1 stable release, issue also occurred on 3.2 alpha.
Repro scene are attached.
ModifierStack_GPUSubdiv_BadPerformance.blend
blender_ksRjvVXVIX.mp4

Exact steps for others to reproduce the error

Open the scene file and try to change the Bend Angle on Simple Deform modifier.
Now Toggle the GPU Subdiv settings and repeat step one.
There's should be a performance difference when GPU Subdiv are enabled.

or just watch the attached video of a flailing magazine

**System Information** Operating system: Windows-10-10.0.19044-SP0 64 Bits Graphics card: NVIDIA GeForce GTX 1070/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 511.23 **Blender Version** Broken: version: 3.2.0 Alpha, branch: master, commit date: 2022-03-14 00:08, hash: `b959f603da`. Also broken in 3.1.0 Stable release. Worked: None i can find. I'm getting bad perfomance when using Modifier stacks and GPU Subdivision are enabled. the video are recorded on 3.1 stable release, issue also occurred on 3.2 alpha. Repro scene are attached. [ModifierStack_GPUSubdiv_BadPerformance.blend](https://archive.blender.org/developer/F12926703/ModifierStack_GPUSubdiv_BadPerformance.blend) [blender_ksRjvVXVIX.mp4](https://archive.blender.org/developer/F12926702/blender_ksRjvVXVIX.mp4) **Exact steps for others to reproduce the error** 1. Open the scene file and try to change the Bend Angle on Simple Deform modifier. 2. Now Toggle the GPU Subdiv settings and repeat step one. 3. There's should be a performance difference when GPU Subdiv are enabled. or just watch the attached video of a flailing magazine

Arie Leo commented

2022-03-14 13:24:40 +01:00

Added subscriber: @reanimate

blender-admin commented

2022-03-14 13:24:40 +01:00

#97182 was marked as duplicate of this issue

Germano Cavalcante commented

2022-03-16 17:02:21 +01:00

Added subscribers: @kevindietrich, @mano-wii

Germano Cavalcante commented

2022-03-16 17:02:21 +01:00

Changed status from 'Needs Triage' to: 'Needs Developer To Reproduce'

Germano Cavalcante commented

2022-03-16 17:02:21 +01:00

I can confirm the delay in the example presented in the file.
The GPU subdivision update is 1/5 of the CPU subdivision performance.
@kevindietrich, any idea why this is happening?

Operating system: Windows-10-10.0.22000-SP0 64 Bits
Graphics card: Radeon (TM) RX 480 Graphics ATI Technologies Inc. 4.5.14802 Core Profile/Debug Context 22.2.3 30.0.14029.5006

I can confirm the delay in the example presented in the file. The GPU subdivision update is 1/5 of the CPU subdivision performance. @kevindietrich, any idea why this is happening? --- Operating system: Windows-10-10.0.22000-SP0 64 Bits Graphics card: Radeon (TM) RX 480 Graphics ATI Technologies Inc. 4.5.14802 Core Profile/Debug Context 22.2.3 30.0.14029.5006

Kévin Dietrich commented

2022-03-21 07:35:49 +01:00

This is because the viewport statistics require a the final mesh for the number of triangles/vertices/etc. so the subdivision is evaluated twice: on the CPU and on the GPU. I'm not sure yet how we can improve the situation, maybe by caching the stats when evaluating on the GPU.

Kévin Dietrich changed title from ~~Modifier Stack causing bad performance on GPU Subdivision~~ to Bad GPU Subdivision performance with viewport statistics

2022-03-21 07:43:36 +01:00

Kévin Dietrich commented

2022-03-21 07:43:36 +01:00

Changed status from 'Needs Developer To Reproduce' to: 'Confirmed'

Arie Leo commented

2022-03-23 07:58:55 +01:00

In #96434#1326519, @kevindietrich wrote:
This is because the viewport statistics require a the final mesh for the number of triangles/vertices/etc. so the subdivision is evaluated twice: on the CPU and on the GPU. I'm not sure yet how we can improve the situation, maybe by caching the stats when evaluating on the GPU.

Oooh interesting, turning off statistics did bring back the performance.
Hmm how about delaying the update of the statistics? ie on mouse click up event?

> In #96434#1326519, @kevindietrich wrote: > This is because the viewport statistics require a the final mesh for the number of triangles/vertices/etc. so the subdivision is evaluated twice: on the CPU and on the GPU. I'm not sure yet how we can improve the situation, maybe by caching the stats when evaluating on the GPU. Oooh interesting, turning off statistics did bring back the performance. Hmm how about delaying the update of the statistics? ie on mouse click up event?

Kévin Dietrich commented

2022-03-23 15:14:28 +01:00

In #96434#1328333, @reanimate wrote:
Oooh interesting, turning off statistics did bring back the performance.
Hmm how about delaying the update of the statistics? ie on mouse click up event?

The statistics update is part of the 3D view draw code, they will be refreshed on each redraw event, it is not really possible to discriminate those events and know which one to delay statistics, and how the delay should be defined.

> In #96434#1328333, @reanimate wrote: > Oooh interesting, turning off statistics did bring back the performance. > Hmm how about delaying the update of the statistics? ie on mouse click up event? The statistics update is part of the 3D view draw code, they will be refreshed on each redraw event, it is not really possible to discriminate those events and know which one to delay statistics, and how the delay should be defined.

Arie Leo commented

2022-03-23 16:10:55 +01:00

In #96434#1328661, @kevindietrich wrote:

In #96434#1328333, @reanimate wrote:
Oooh interesting, turning off statistics did bring back the performance.
Hmm how about delaying the update of the statistics? ie on mouse click up event?

The statistics update is part of the 3D view draw code, they will be refreshed on each redraw event, it is not really possible to discriminate those events and know which one to delay statistics, and how the delay should be defined.

I see, this is kinda problematic. Thanks for the information

> In #96434#1328661, @kevindietrich wrote: >> In #96434#1328333, @reanimate wrote: >> Oooh interesting, turning off statistics did bring back the performance. >> Hmm how about delaying the update of the statistics? ie on mouse click up event? > > The statistics update is part of the 3D view draw code, they will be refreshed on each redraw event, it is not really possible to discriminate those events and know which one to delay statistics, and how the delay should be defined. I see, this is kinda problematic. Thanks for the information

Kévin Dietrich commented

2022-04-09 10:06:57 +02:00

Added subscriber: @Smjert

Philipp Oeser changed title from ~~Bad GPU Subdivision performance with viewport statistics~~ to GPU subdivision: Bad performance with viewport statistics

2022-04-12 16:45:11 +02:00

Philipp Oeser commented

2022-04-13 11:14:56 +02:00

Added subscriber: @lichtwerk

Philipp Oeser commented

2022-04-13 11:14:56 +02:00

Talked to @kevindietrich , setting to High prio (since it is a bug in a new feature according to the playbook

Talked to @kevindietrich , setting to High prio (since it is a bug in a new feature according to the [playbook ](https://wiki.blender.org/wiki/Process/Bug_Reports/Triaging_Playbook)

Brecht Van Lommel commented

2022-04-26 16:31:20 +02:00

Added subscriber: @brecht

Brecht Van Lommel commented

2022-04-26 16:31:20 +02:00

Could we compute the stats without actually performing the subdivision? Or even just provide a rough estimate? I don't think the exact number is even that important, some guess based on the subdivision level could be enough.

Kévin Dietrich commented

2022-04-27 13:58:07 +02:00

Actually we can just get the counters from the draw code's subdivision grid traversal, they are cached there anyway.

blender-admin commented

2022-04-27 15:30:17 +02:00

This issue was referenced by 163f6a17e4

This issue was referenced by 163f6a17e4fe60ce917715afc5bb5eae3d5ff07a

Kévin Dietrich commented

2022-04-27 15:30:48 +02:00

Changed status from 'Confirmed' to: 'Resolved'

Kévin Dietrich closed this issue

2022-04-27 15:30:48 +02:00

Kévin Dietrich self-assigned this 2022-04-27 15:30:48 +02:00

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GPU subdivision: Bad performance with viewport statistics #96434