Cycles Optix rendering slows down on second tile #75955

New Issue

Łukasz · 2020-04-21T10:00:21+02:00

Łukasz commented

2020-04-21 10:00:21 +02:00

System Information
Operating system:Windows 10
Graphics card: 1x Nvidia RTX 2080 Ti

Blender Version
Broken: Blender 2.82a
Worked: every previous version

When I render on Optix sometimes (50% times) rendering goes extremely slow after rendering the first tile of render

This is happening to me only on hudge scenes like 1,44GB. And this is not happening every time but quite often ( 50% of times )
To Explain that let's just assume that we have an interior scene which has nothing special in it ( I know that optix is not working with AO shader and branched path tracing)

I hit render and first tile is rendering really fast and when I'm checking how my card is vorking cuda usage looks like this:
But after rendering first tile, second goest extremely slow and my cuda usage looks like this

and expected time of rendering goes from 1 hour up to 15 hours or even 20 hours

I know that you might say that not every tile is rendering with the same speed but that is not an issue. When I restart PC or sometimes when I restart blender or sometimes when I prerender scene for something like 1 minute with material override option enabled render goes in the correct way. What I mean by that is that:

I hit render (same camera same samples and all other settings)
Render goes with almost same fast speed on every tile and full render is acomplished after 1 hour. My cuda usage looks like this:

As I wrote before this happens to me only on complicated hudge scenes but my work consits only those type of scenes ( I'm interior designer)
I have this problem since the first release of blender with optix rendering. I,ve also checked tenperatures on my GPU and nothing goes above 66 degrees.
Here is my file but it is quite large 1,44 GB:
poznań restauracja zmiany evee zmiany ewa textury small.blend

For me it is hude deal if my render goes 1 hour or 15 hours so pls help me :)

**System Information** Operating system:Windows 10 Graphics card: 1x Nvidia RTX 2080 Ti **Blender Version** Broken: Blender 2.82a Worked: every previous version When I render on Optix sometimes (50% times) rendering goes extremely slow after rendering the first tile of render This is happening to me only on hudge scenes like 1,44GB. And this is not happening every time but quite often ( 50% of times ) To Explain that let's just assume that we have an interior scene which has nothing special in it ( I know that optix is not working with AO shader and branched path tracing) 1. I hit render and first tile is rendering really fast and when I'm checking how my card is vorking cuda usage looks like this: ![94129783_231146671280322_3052305825587527680_n.jpg](https://archive.blender.org/developer/F8486645/94129783_231146671280322_3052305825587527680_n.jpg) 2. But after rendering first tile, second goest extremely slow and my cuda usage looks like this ![93826820_253089662483262_7563975413039366144_n.jpg](https://archive.blender.org/developer/F8486647/93826820_253089662483262_7563975413039366144_n.jpg) and expected time of rendering goes from 1 hour up to 15 hours or even 20 hours I know that you might say that not every tile is rendering with the same speed but that is not an issue. When I restart PC or sometimes when I restart blender or sometimes when I prerender scene for something like 1 minute with material override option enabled render goes in the correct way. What I mean by that is that: 1. I hit render (same camera same samples and all other settings) 2. Render goes with almost same fast speed on every tile and full render is acomplished after 1 hour. My cuda usage looks like this: ![94129783_231146671280322_3052305825587527680_n.jpg](https://archive.blender.org/developer/F8486656/94129783_231146671280322_3052305825587527680_n.jpg) As I wrote before this happens to me only on complicated hudge scenes but my work consits only those type of scenes ( I'm interior designer) I have this problem since the first release of blender with optix rendering. I,ve also checked tenperatures on my GPU and nothing goes above 66 degrees. Here is my file but it is quite large 1,44 GB: [poznań restauracja zmiany evee zmiany ewa textury small.blend](https://archive.blender.org/developer/F8486684/poznań_restauracja_zmiany_evee_zmiany_ewa_textury_small.blend) For me it is hude deal if my render goes 1 hour or 15 hours so pls help me :)

Łukasz commented

2020-04-21 10:00:21 +02:00

Added subscriber: @sohoha

blender-admin commented

2020-04-21 10:00:21 +02:00

#75954 was marked as duplicate of this issue

Brecht Van Lommel commented

2020-04-21 12:19:21 +02:00

Added subscribers: @pmoursnv, @brecht

Brecht Van Lommel commented

2020-04-21 12:19:21 +02:00

Changed status from 'Needs Triage' to: 'Needs User Info'

Brecht Van Lommel commented

2020-04-21 12:19:21 +02:00

Can you run blender_debug_log.cmd included with Blender, do the render, and attach the resulting logs here? This will include more detailed info about what Cycles is doing.

Does this happen when rendering with CUDA instead of Optix?

Maybe it's running out of GPU memory somewhere and then falling back to slower CPU memory.

Can you run `blender_debug_log.cmd` included with Blender, do the render, and attach the resulting logs here? This will include more detailed info about what Cycles is doing. Does this happen when rendering with CUDA instead of Optix? Maybe it's running out of GPU memory somewhere and then falling back to slower CPU memory.

Łukasz commented

2020-04-22 15:06:42 +02:00

Rendering on cuda sometimes also crashes but this is less often than on Optix
Here is debug log:
blender_debug_output.txt

blender_system_info.txt

I've also found out that doing prerender with material override option enabled with simple principled BSDF helps 100% of times. But I have no idea what is causing that behaviour.

Rendering on cuda sometimes also crashes but this is less often than on Optix Here is debug log: [blender_debug_output.txt](https://archive.blender.org/developer/F8489240/blender_debug_output.txt) [blender_system_info.txt](https://archive.blender.org/developer/F8489239/blender_system_info.txt) I've also found out that doing prerender with material override option enabled with simple principled BSDF helps 100% of times. But I have no idea what is causing that behaviour.

Brecht Van Lommel commented

2020-04-22 15:17:54 +02:00

This is probably the issue:

I0422 14:35:43.520292  3788 device_optix.cpp:2117] Move memory from device to host: __tex_image_byte4_033
I0422 14:35:43.579133  3788 device_optix.cpp:1647] Buffer allocate: __tex_image_byte4_033, 67,108,864 bytes. (64.00M) in host memory
I0422 14:35:43.593094  3788 device_optix.cpp:1647] Buffer allocate: __texture_info, 42,784 bytes. (41.78K) in host memory
I0422 14:35:43.609052  3788 device_optix.cpp:1647] Buffer allocate: RenderBuffers, 24,883,200 bytes. (23.73M) in host memory

In general __texture_info and RenderBuffers should not be allocated in host memory because it's too slow. Instead moving more __tex_image to the host should be preferred.

This is probably the issue: ``` I0422 14:35:43.520292 3788 device_optix.cpp:2117] Move memory from device to host: __tex_image_byte4_033 I0422 14:35:43.579133 3788 device_optix.cpp:1647] Buffer allocate: __tex_image_byte4_033, 67,108,864 bytes. (64.00M) in host memory I0422 14:35:43.593094 3788 device_optix.cpp:1647] Buffer allocate: __texture_info, 42,784 bytes. (41.78K) in host memory I0422 14:35:43.609052 3788 device_optix.cpp:1647] Buffer allocate: RenderBuffers, 24,883,200 bytes. (23.73M) in host memory ``` In general `__texture_info` and `RenderBuffers` should not be allocated in host memory because it's too slow. Instead moving more `__tex_image` to the host should be preferred.

Brecht Van Lommel commented

2020-04-22 15:18:11 +02:00

Changed status from 'Needs User Info' to: 'Needs Developer To Reproduce'

Łukasz commented

2020-05-22 10:43:21 +02:00

Problem is still ongoing. I've made two render logs. One is correct with remaining render time around 1h. Second one is with crash I've described above and it's remaining time is around 150 hours. All settings are the same except for number of objets in the scene which for Right render scen is smaller. I know that you may say that crash ocurs according to number of objects in the scene however it is not that simple because Sometimes it can crash on one scene and next time it may go perfectly smoth with next render
blender right optix render.rar

blender wrong optix render.rar

Problem is still ongoing. I've made two render logs. One is correct with remaining render time around 1h. Second one is with crash I've described above and it's remaining time is around 150 hours. All settings are the same except for number of objets in the scene which for Right render scen is smaller. I know that you may say that crash ocurs according to number of objects in the scene however it is not that simple because Sometimes it can crash on one scene and next time it may go perfectly smoth with next render [blender right optix render.rar](https://archive.blender.org/developer/F8547379/blender_right_optix_render.rar) [blender wrong optix render.rar](https://archive.blender.org/developer/F8547378/blender_wrong_optix_render.rar)

Łukasz commented

2020-05-22 10:57:56 +02:00

Here is the scene
poznań restauracja zmiany evee zmiany ewa8 textury small temp to render3.blend

Here is the scene [poznań restauracja zmiany evee zmiany ewa8 textury small temp to render3.blend](https://archive.blender.org/developer/F8547394/poznań_restauracja_zmiany_evee_zmiany_ewa8_textury_small_temp_to_render3.blend)

Richard Antalik commented

2020-11-26 18:57:49 +01:00

Added subscriber: @iss

Richard Antalik commented

2020-11-26 18:57:49 +01:00

Changed status from 'Needs Developer To Reproduce' to: 'Needs User Info'

Richard Antalik commented

2020-11-26 18:57:49 +01:00

@sohoha I am looking at older reports, According to comments in D7426 this should be resolved already. Can you confirm this?

@sohoha I am looking at older reports, According to comments in [D7426](https://archive.blender.org/developer/D7426) this should be resolved already. Can you confirm this?

Philipp Oeser commented

2021-01-17 22:15:58 +01:00

Added subscriber: @lichtwerk

Philipp Oeser commented

2021-01-17 22:15:58 +01:00

Changed status from 'Needs User Info' to: 'Archived'

Philipp Oeser closed this issue

2021-01-17 22:15:58 +01:00

Philipp Oeser commented

2021-01-17 22:15:58 +01:00

No activity for more than a week. As per the tracker policy we assume the issue is gone and can be closed.

Thanks again for the report. If the problem persists please open a new report with the required information.

No activity for more than a week. As per the tracker policy we assume the issue is gone and can be closed. Thanks again for the report. If the problem persists please open a new report with the required information.

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Cycles Optix rendering slows down on second tile #75955