OpenGL/Nvidia Performance on windows #70167

New Issue

Ray molenkamp · 2019-09-22T21:19:37+02:00

Ray molenkamp commented

2019-09-22 21:19:37 +02:00

While profiling the openXR branch where even the default cube only runs at a disappointing 45 fps i stumbled upon drw_engine_init running every frame and doing some rather expensive operations every single frame which is 'not great'

we recently removed one of those operations from the GP init but there's still plenty of others left

A quick profile shows the following flame graph

Both GPU_Draw_List_Init and GPU_Buf_Alloc seem to trigger behavior in the nvidia driver that causes it to spin off a thread and wait for it to exit, not something you'd want to do every frame (or multiple times a frame, hard to tell from a flame graph)

Discussed on chat and you requested a task low prio task for this for further investigation

CC : @fclem , @brecht

While profiling the openXR branch where even the default cube only runs at a disappointing 45 fps i stumbled upon `drw_engine_init` running every frame and doing some rather expensive operations every single frame which is 'not great' we recently removed one of those operations from the GP init but there's still plenty of others left A quick profile shows the following flame graph ![image.png](https://archive.blender.org/developer/F7770702/image.png) Both `GPU_Draw_List_Init` and `GPU_Buf_Alloc` seem to trigger behavior in the nvidia driver that causes it to spin off a thread and wait for it to exit, not something you'd want to do every frame (or multiple times a frame, hard to tell from a flame graph) Discussed on chat and you requested a task low prio task for this for further investigation CC : @fclem , @brecht

Jeroen Bakker was assigned by Ray molenkamp

2019-09-22 21:19:37 +02:00

Ray molenkamp commented

2019-09-22 21:19:37 +02:00

Added subscribers: @fclem, @brecht, @LazyDodo

Jeroen Bakker commented

2019-09-23 14:02:48 +02:00

The workbench creates a UBO for AO samples And world data.

Samples UBO

Dont think it is related to the TAA/AO samples. These are being guarded, but might not that is not cached when multiple viewports with different settings are active. If that is the case the second view will re-validate the cache created by the first view and vise versa.

https://developer.blender.org/diffusion/B/browse/master/source/blender/draw/engines/workbench/workbench_deferred.c$548-567

World UBO

The world UBO is generated on every draw call. It is not guarded. It is 304 bytes. This data is best cacheable per viewport and not globally. Otherwise it there is a slight chance of a cache hit between viewports.

Draw list

The draw list can be huge (mesh data) so that is not something I want to mess with.

Improvements

I would expect we can cache the World UBO per viewport

The workbench creates a UBO for AO samples And world data. ## Samples UBO Dont think it is related to the TAA/AO samples. These are being guarded, but might not that is not cached when multiple viewports with different settings are active. If that is the case the second view will re-validate the cache created by the first view and vise versa. https://developer.blender.org/diffusion/B/browse/master/source/blender/draw/engines/workbench/workbench_deferred.c$548-567 ## World UBO The world UBO is generated on every draw call. It is not guarded. It is 304 bytes. This data is best cacheable per viewport and not globally. Otherwise it there is a slight chance of a cache hit between viewports. ## Draw list The draw list can be huge (mesh data) so that is not something I want to mess with. ## Improvements I would expect we can cache the World UBO per viewport

Clément Foucault commented

2019-10-17 22:43:05 +02:00

I guess this is hitting a driver slow path.
Draw list : We should maybe use SSBO + Persistent mapping instead of creating / freeing potentially lots of UBOs.
Workbench : All UBOs are rather small. I agree they should use update instead of being re-specified every time if it does not add too much complexity.

I guess this is hitting a driver slow path. Draw list : We should maybe use SSBO + Persistent mapping instead of creating / freeing potentially lots of UBOs. Workbench : All UBOs are rather small. I agree they should use update instead of being re-specified every time if it does not add too much complexity.

Jeroen Bakker commented

2019-11-27 16:15:28 +01:00

Changed status from 'Open' to: 'Resolved'

Jeroen Bakker closed this issue

2019-11-27 16:15:28 +01:00

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OpenGL/Nvidia Performance on windows #70167

Samples UBO

World UBO

Draw list

Improvements