[Bf-cycles] Question about NVIDIA GPU resources capping when rendering

Brecht Van Lommel brechtvanlommel at pandora.be
Wed Feb 20 14:08:41 CET 2013


On Tue, Feb 19, 2013 at 9:20 PM, Impossible 3D
<impossible3d.media at gmail.com> wrote:
> I was wondering if someone knew if resources capping was available in
> the nvidia driver and if Blender could maybe get control over it which
> would allow such a feature (I was putting forward a suggestion that a
> textbox option besides the "GPU compute" option that would allow for a
> maximum percent value to be entered and thus would allow some sort of
> control by the user, for example during the day it would render frames
> at 60-80% GPU (and hopefully, the computer would stop lagging), and at
> night or when afk for a long time, it would go back at 100% GPU). It may
> not even need this level of granularity in case it's a pain to
> implement, even a low/medium/high/unrestricted selector would be most
> welcome.

We could do better here but it's fairly complicated. The way a GPU
works is that once you send it a job, it can't do anything else until
that job is finished, it's not possible to do 80% rendering and 20%
drawing simultaneously. The problem is that if you send it too small a
job it will not work efficiently, if you send it too large of a job it
will not be able to redraw the screen until it's done.

Using smaller tile sizes will give you smaller jobs and so more
responsive UI. We could have an extra option here to also do nothing
after each job, I think this would lower the heat but not necessarily
make the UI much more responsive.

But the only way to get really smooth interaction is to use separate
GPU's for rendering and display, as most GPU render engines recommend.


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