Cycles Rendering Drastically Slower Since 2.8 Update #69230

New Issue

Brandon Garvie · 2019-08-28T00:03:37+02:00

Brandon Garvie commented

2019-08-28 00:03:37 +02:00

System Information
Operating system: Windows-10-10.0.16299 64 Bits
Graphics card: GeForce GTX 770/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 436.15

Blender Version
Broken: version: 2.80 (sub 75), branch: master, commit date: 2019-07-29 14:47, hash: f6cb5f5449
Worked: (optional)

Short description of error
All rendering done with the cycles engine has been much slower in 2.8 than it was in 2.79. A quick test using suzanne and simple AO baking put the 2.8 render at about 1/4th the speed of the 2.79 render. This is consistent with normal render results I've been getting since the update.
Simple AO Bake.blend

Should also mention that during GPU rendering in 2.8, CPU usage shoots up to 100% while GPU usage hovers around 15-20%. In 2.79, CPU usage hovers around 35-40% and GPU usage shoots up to 20% when the bake starts and then drops back down.

**System Information** Operating system: Windows-10-10.0.16299 64 Bits Graphics card: GeForce GTX 770/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 436.15 **Blender Version** Broken: version: 2.80 (sub 75), branch: master, commit date: 2019-07-29 14:47, hash: `f6cb5f5449` Worked: (optional) **Short description of error** All rendering done with the cycles engine has been much slower in 2.8 than it was in 2.79. A quick test using suzanne and simple AO baking put the 2.8 render at about 1/4th the speed of the 2.79 render. This is consistent with normal render results I've been getting since the update. [Simple AO Bake.blend](https://archive.blender.org/developer/F7706874/Simple_AO_Bake.blend) Should also mention that during GPU rendering in 2.8, CPU usage shoots up to 100% while GPU usage hovers around 15-20%. In 2.79, CPU usage hovers around 35-40% and GPU usage shoots up to 20% when the bake starts and then drops back down.

Brandon Garvie commented

2019-08-28 00:03:37 +02:00

Added subscriber: @Bacn-3

blender-admin commented

2019-08-28 00:03:37 +02:00

#72237 was marked as duplicate of this issue

Philipp Oeser commented

2019-08-29 10:13:04 +02:00

Added subscribers: @brecht, @lichtwerk

Philipp Oeser commented

2019-08-29 10:13:04 +02:00

Cannot reproduce here. (linux, 970m, 430.26 drivers)
Here are my baking times:

2.81master buildbot GPU: 13.99sec
2.81master buildbot CPU: 18.96sec

2.79branch buildbot GPU: 13.34sec
2.79branch buildbot CPU: 18.32sec

This is just a shot in the dark / gut feeling: for me at least nvidia doesnt offer these 436.XX drivers, but is there possibly something wrong with these drivers, I think there was another report that I could not reproduce either (reporter also used these drivers)? Could you check if this has different results with 430.XX drivers?

CC @brecht

Cannot reproduce here. (linux, 970m, 430.26 drivers) Here are my baking times: ``` 2.81master buildbot GPU: 13.99sec 2.81master buildbot CPU: 18.96sec 2.79branch buildbot GPU: 13.34sec 2.79branch buildbot CPU: 18.32sec ``` This is just a shot in the dark / gut feeling: for me at least nvidia doesnt offer these 436.XX drivers, but is there possibly something wrong with these drivers, I think there was another report that I could not reproduce either (reporter also used these drivers)? Could you check if this has different results with 430.XX drivers? CC @brecht

Philipp Oeser changed title from ~~Cyclesw Rendering Drastically Slower Since 2.8 Update~~ to Cycles Rendering Drastically Slower Since 2.8 Update

2019-08-29 10:13:23 +02:00

Brandon Garvie commented

2019-08-29 18:13:44 +02:00

Downgraded from 436.15 to 430.86, no changes in render time or hardware usage.

Philipp Oeser commented

2019-08-29 21:57:10 +02:00

OKi, thx for getting back

Ray molenkamp commented

2019-08-29 22:34:13 +02:00

Added subscriber: @LazyDodo

Ray molenkamp commented

2019-08-29 22:34:13 +02:00

I can repro on windows, but not as drastic as @Bacn-3

2.79 buildbot 18 seconds
2.80 buildbot 24 seconds.

2.79 does seem to use the gpu more efficiently

I can repro on windows, but not as drastic as @Bacn-3 ``` 2.79 buildbot 18 seconds 2.80 buildbot 24 seconds. ``` 2.79 does seem to use the gpu more efficiently ![image.png](https://archive.blender.org/developer/F7709996/image.png)

Brandon Garvie commented

2019-10-04 08:31:06 +02:00

Think I found what the problem was. In user preferences the cycles render devices setting was changes to 'none', I'm guessing this happened by default in 2.8 for some reason. After switching it to 'CUDA', GPU and CPU usage has returned to what was expected. Blender must have been using CPU rendering despite it letting me still select GPU rendering from the dropdown in the render settings.

Could test it some more, but at this point I think it's safe to say it's just a UI mixup.

Think I found what the problem was. In user preferences the cycles render devices setting was changes to 'none', I'm guessing this happened by default in 2.8 for some reason. After switching it to 'CUDA', GPU and CPU usage has returned to what was expected. Blender must have been using CPU rendering despite it letting me still select GPU rendering from the dropdown in the render settings. Could test it some more, but at this point I think it's safe to say it's just a UI mixup.

Maciej Jutrzenka commented

2019-12-06 21:01:41 +01:00

Added subscribers: @artutava, @MaciejJutrzenka

Artur Tavares commented

2019-12-06 21:04:54 +01:00

Baking here with two gpus only uses one gpu and CPU usage is much higher than GPU usage...

In MSI afterburner percentage is a bit different.. But its the same thing.. CPU has a much higher usage.. 13% on GPU versus 58% on CPU.

![image.png](https://archive.blender.org/developer/F8194328/image.png) Baking here with two gpus only uses one gpu and CPU usage is much higher than GPU usage... In MSI afterburner percentage is a bit different.. But its the same thing.. CPU has a much higher usage.. 13% on GPU versus 58% on CPU. ![image.png](https://archive.blender.org/developer/F8194337/image.png) ![image.png](https://archive.blender.org/developer/F8194339/image.png)

Artur Tavares commented

2019-12-06 22:41:50 +01:00

The same happens while rendering a scene... Not just baking...

The right parameter to measure is just the use of cuda cores? Because if it is... then it seems to use over 90%

The same happens while rendering a scene... Not just baking... ![image.png](https://archive.blender.org/developer/F8194658/image.png) ![image.png](https://archive.blender.org/developer/F8194661/image.png) The right parameter to measure is just the use of cuda cores? Because if it is... then it seems to use over 90%

Jacques Lucke commented

2020-01-21 15:16:10 +01:00

Added subscriber: @JacquesLucke

Jacques Lucke commented

2020-01-21 15:16:10 +01:00

Changed status from 'Needs Triage' to: 'Archived'

Jacques Lucke closed this issue

2020-01-21 15:16:10 +01:00

Jacques Lucke self-assigned this 2020-01-21 15:16:10 +01:00

Jacques Lucke commented

2020-01-21 15:16:11 +01:00

Closing because the original issue from @Bacn-3 seems to be resolved.

Just because the CPU usage is higher than the GPU usage does not seem to be a good enough reason for a bug report. If you think there is a real regression here, please open a new report.

Closing because the original issue from @Bacn-3 seems to be resolved. Just because the CPU usage is higher than the GPU usage does not seem to be a good enough reason for a bug report. If you think there is a real regression here, please open a new report.

Sign in to join this conversation.

No Label

Download

What's New

Blender Studio

Manual

Developers Blog

Documentation

Benchmark

Blender Conference

Development Fund

One-time Donations

Cycles Rendering Drastically Slower Since 2.8 Update #69230