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

[Brecht Van Lommel]

Thanks for the detailed reported, it will help a lot in fixing this bug.

On Sun, Jun 23, 2013 at 8:00 PM, David Black <db4tech at yahoo.co.uk> wrote:
> 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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