[Bf-cycles] Blender Viewport performance issue after Cycles render (since changing to CUDA Toolkit 5.0)

David Black db4tech at yahoo.co.uk
Sun Jun 23 20:21:11 CEST 2013

No problem Thomas, with it being Cycles related and BuildBot builds 
thought this was the correct place.


On 23/06/2013 19:05, Thomas Dinges wrote:
> David,
> please report issues to our bug tracker and not to the mailing list, 
> much easier to track problems there. :)
> Am 23.06.2013 20:00, schrieb David Black:
>> On 23/06/2013 18:03, Brecht Van Lommel wrote:
>>> I have no idea how this is possible, all the toolkit changes is code
>>> that runs on the NVidia graphics card, not how it interacts with other
>>> graphics drivers. So perhaps it's another recent change in Cycles or
>>> elsewhere in Blender that is causing this?
>> Apologies, not Toolkit 5.0 related, after performing your tests below 
>> discovered it goes back further.
>>> * What is the version number of the build before the toolkit change
>>> that still gave good performance (to narrow down the revisions)?
>> *blender-2.67-r57293-win64* is okay, Viewport performance same before 
>> and after F12 Cycles render.
>> *blender-2.67-r57348-mingw64* Is okay except for border render issue, 
>> otherwise same as above.
>> *blender-2.67-r57476-win64* First versions (I have) that shows the 
>> issue, Viewport performance same as previous version until F12 Cycles 
>> render, then very slow jerky Viewport performance.
>>> * Does this really only happen with GPU rendering, CPU rendering does
>>> not show the same issue?
>> Interesting test idea. Same issue after either GPU or CPU F12 Cycles 
>> render
>>> * What is performance like with VBO's switched off before rendering
>>> (in case the rendering somehow switches them off)?
>> Not as smooth, around 10-15fps but still faster than after rendering, 
>> which then feels around 2fps.
>>> * What is the performance like with the NVidia card, is it also 2fps
>>> or somewhere in between?
>> Not yet tested, once wiring configurations are changed will email 
>> results. Thought quick reply with above answers would be appreciated.
>>> * Is a Blender restart needed or does reopening the scene solve the issue too?
>> Interesting, reopening the same scene without restarting Blender also 
>> solves the issue, until an F12 Cycles render is performed.
>> David
>>> Can anyone else confirm this problem?
>>> On Sun, Jun 23, 2013 at 5:36 PM, David Black<db4tech at yahoo.co.uk>  wrote:
>>>> Hi Brecht,
>>>> Just discovered an interesting issue, seems to have been introduced since
>>>> Blender changed to CUDA Toolkit 5.0. Not related to Cycles render speeds,
>>>> which consequently have received a great boost after code re-factoring.
>>>> Issue is connected with Viewport performance after performing a Cycles
>>>> render.
>>>> Issue outlined below:
>>>> Upon opening a complex scene, with a heavy particle system (particles
>>>> Viewport setting of 1, Child particles 0), Viewport navigation (VOBs
>>>> enabled) with an Intel HD 4000 (part of i7 CPU) is extremely fluid, like
>>>> 30fps or more, (much slower on GTX 580 due to double sided Normals
>>>> restrictions).
>>>> With recent Blender versions, everything is fine until a F12 Cycles render
>>>> is performed (does not happen with Viewport render), after which Viewport
>>>> navigation becomes extremely sluggish, feels like 2fps. Hiding the heavy
>>>> particle object returns full Viewport performance, once object is unhidden
>>>> Viewport is back to a crawl. Closing and opening Blender with the same scene
>>>> and everything is back to normal, until the next F12 render is performed.
>>>> Blender versions prior to Toolkit 5.0 changes, Viewport performance remains
>>>> just as fluid after a F12 Cycles render, also tested Blender 2.67b.
>>>> Today's BuildBot version (official) blender-2.67-r57660-win64 produces the
>>>> sluggish Viewport issue after a F12 Cycles render.
>>>> David
>>>> --
>>>> 3d-designs-davidblack.blogspot.com
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>>>> http://lists.blender.org/mailman/listinfo/bf-cycles
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> -- 
> Thomas Dinges
> Blender Developer, Artist and Musician
> www.dingto.org
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