Using Cycles as a viewport renderer with single GPU causes extreme UI lag on Windows #56828

New Issue

Ludvik Koutny · 2018-09-17T15:11:40+02:00

Ludvik Koutny commented

2018-09-17 15:11:40 +02:00

System Information
Windows 10, GTX1080Ti, 399.24 drivers

Blender Version
Broken: Latest 2.79 Master, 2.8 - Sep 17 2018
Worked: probably never

Short description of error
On Windows 10, with single GPU, running Cycles as interactive viewport renderer results in severe UI lag as soon as scene reaches certain shading complexity. Using the very same single GPU setup to render a final frame (F12 key) results in no UI lag. Therefore Cycles GPU utilization is handled differently (worse) for viewport rendering.

Exact steps for others to reproduce the error
1, Test on a Windows 10 machine with a single CUDA capable GPU
2, Open a scene of higher complexity which can render on the GPU (Classroom or Victor scene will do)
3, Set active viewport mode to rendered.
4, Increase preview Cycles samples to reasonable amount (128)
5, Perform an action to induce Cycles viewport update
6, Try to interact with UI while viewport renders

Result: Blender's UI lags heavily during rendered viewport update

Expected: Performance penalty for viewport GPU rendering should be same as for final frame GPU rendering - no UI lag.

**System Information** Windows 10, GTX1080Ti, 399.24 drivers **Blender Version** Broken: Latest 2.79 Master, 2.8 - Sep 17 2018 Worked: probably never **Short description of error** On Windows 10, with single GPU, running Cycles as interactive viewport renderer results in severe UI lag as soon as scene reaches certain shading complexity. Using the very same single GPU setup to render a final frame (F12 key) results in no UI lag. Therefore Cycles GPU utilization is handled differently (worse) for viewport rendering. **Exact steps for others to reproduce the error** 1, Test on a Windows 10 machine with a single CUDA capable GPU 2, Open a scene of higher complexity which can render on the GPU (Classroom or Victor scene will do) 3, Set active viewport mode to rendered. 4, Increase preview Cycles samples to reasonable amount (128) 5, Perform an action to induce Cycles viewport update 6, Try to interact with UI while viewport renders Result: Blender's UI lags heavily during rendered viewport update Expected: Performance penalty for viewport GPU rendering should be same as for final frame GPU rendering - no UI lag.

Ludvik Koutny commented

2018-09-17 15:11:40 +02:00

Added subscriber: @Rawalanche

Ludvik Koutny changed title from ~~Using Cycles as a viewport rendered with single GPU causes extreme UI lag on Windows~~ to Using Cycles as a viewport renderer with single GPU causes extreme UI lag on Windows

2018-09-17 15:11:56 +02:00

Bastien Montagne commented

2018-09-18 09:29:16 +02:00

Added subscribers: @brecht, @mont29

Brecht Van Lommel was assigned by Bastien Montagne

2018-09-18 09:29:16 +02:00

Bastien Montagne commented

2018-09-18 09:29:16 +02:00

I’d bet that’s more like known limitation than bug, but will let you decide her, @brecht.