GPU renders slower after first one #41444

New Issue

James Boddie · 2014-08-14T22:57:07+02:00

James Boddie commented

2014-08-14 22:57:07 +02:00

System Information
Windows 8.1, 64 bit, CPU: i7 860, GPU EVGA GTX750ti 2GB, Driver: 340.52

Blender Version
2.71

Short description of error
With a scene that uses more than 1.5GB but less than 2GB, the first GPU render is fast. Subsequent renders (without going to the 3D View) are much slower. The first render after returning to the 3D view is fast again.

In one case, the CPU render time is always 1:12. The first GPU render is 0:34 the subsequent render times are 1:04, 1:19, 1:21. If I escape to the 3D View and render again, the time drops back to 0:34.

So I am obviously running low on GPU memory but the out-of-memory message does not appear and it does seem like some GPU memory is retained (but not shown on the usage display) when rendering from the Image View.

Exact steps for others to reproduce the error

**System Information** Windows 8.1, 64 bit, CPU: i7 860, GPU EVGA GTX750ti 2GB, Driver: 340.52 **Blender Version** 2.71 **Short description of error** With a scene that uses more than 1.5GB but less than 2GB, the first GPU render is fast. Subsequent renders (without going to the 3D View) are much slower. The first render after returning to the 3D view is fast again. In one case, the CPU render time is always 1:12. The first GPU render is 0:34 the subsequent render times are 1:04, 1:19, 1:21. If I escape to the 3D View and render again, the time drops back to 0:34. So I am obviously running low on GPU memory but the out-of-memory message does not appear and it does seem like some GPU memory is retained (but not shown on the usage display) when rendering from the Image View. **Exact steps for others to reproduce the error**

James Boddie commented

2014-08-14 22:57:07 +02:00

Changed status to: 'Open'

James Boddie commented

2014-08-14 22:57:07 +02:00

Added subscriber: @jrboddie

Bastien Montagne commented

2014-08-15 08:33:01 +02:00

Added subscriber: @mont29

Sergey Sharybin commented

2014-08-15 08:35:22 +02:00

Added subscriber: @Sergey

Sergey Sharybin commented

2014-08-15 08:35:22 +02:00

That's loads of cases when re-rendering from the render result image editor will take more time, even without being a bug. For example, when you're having layer override or when having a local view in the viewport.

In any case, please always attach .blend file (as small as possible) which 100% demonstrates issue for you.

That's loads of cases when re-rendering from the render result image editor will take more time, even without being a bug. For example, when you're having layer override or when having a local view in the viewport. In any case, please always attach .blend file (as small as possible) which 100% demonstrates issue for you.

James Boddie commented

2014-08-15 16:59:36 +02:00

My latest observation is that the slowdown seems to occur predominantly when rendering to Full Screen or New Window. When rendering to Image Editor, the sequential render times are much more consistent with the first render time; however, the first render time is always the fastest.

I rendered an animation with Image Editor selected: 0:31, 0:32, 0:43, 0:35, 0:58, 0:51. Stopped the animation and immediately hit render: 0:31.

Temps are ok. MSI Afterburner reporting 35 - 38 degrees C.

Afterburner is also reporting that the scene is using 2020 MB GPU memory.

Conclusion, my scene is simply too complex for my GPU.

Probably not a bug.

My latest observation is that the slowdown seems to occur predominantly when rendering to Full Screen or New Window. When rendering to Image Editor, the sequential render times are much more consistent with the first render time; however, the first render time is always the fastest. I rendered an animation with Image Editor selected: 0:31, 0:32, 0:43, 0:35, 0:58, 0:51. Stopped the animation and immediately hit render: 0:31. Temps are ok. MSI Afterburner reporting 35 - 38 degrees C. Afterburner is also reporting that the scene is using 2020 MB GPU memory. Conclusion, my scene is simply too complex for my GPU. Probably not a bug.

Thomas Dinges commented

2014-08-19 22:28:33 +02:00

Changed status from 'Open' to: 'Archived'

Thomas Dinges closed this issue

2014-08-19 22:28:33 +02:00

Thomas Dinges self-assigned this 2014-08-19 22:28:33 +02:00

Thomas Dinges commented

2014-08-19 22:28:33 +02:00

Well, Sergey asked you for a blend file, without it we cannot fix it.

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GPU renders slower after first one #41444