[Bf-cycles] Proposal for Compute Device Selection from Blender

Brecht Van Lommel brechtvanlommel at pandora.be
Sat Nov 5 13:19:49 CET 2016

On Sat, Nov 5, 2016 at 10:29 AM, Gottfried Hofmann
<gottfried at blenderdiplom.com> wrote:
> On 05.11.2016 03:46, Brecht Van Lommel wrote:
>> Why would users change the selection of GPU devices regularly?
>> If it is e.g. to disable the display device for interactivity, then
>> perhaps there should be a way to disable a device for viewport renders
>> but enable it for final renders. Or maybe there's another reason I'm
>> unaware of that we can solve in a better way.
> I would prefer full control for several reasons:
> 1. While working, I generally do not want the display device to render,
> but I often have F12 renders in the background. Over night, I also let
> the display device render so I regularly change the selection of GPU devices
> 2. One client of mine has the following configuration:
>    - Display device with 2 GB
>    - An additional card in the workstation with 4 GB (many workstations
> are kinda inflexible in regards of power connectors so that was the best
> option)
>    - An external card with 6 GB
>    The above solution would limit the max preview and render VRAM to 4
> GB. I guess many people have heterogenous configurations.
> 3. I encountered some machines where all GPUs where listed as display
> device. Of course that is a bug, but whenever such a bug is introduced
> it would have a considerable impact on the user experience.
> 4. In general I prefer solutions that offer control to the user. If the
> proposed solution will be implemented, I'd vote for the option to still
> allow a fine-grained selection via Python API so TDs can write custom
> solutions via addons.

To be clear, I think we should let users select individual GPUs, and
an automatically detected display device would not matter anymore. The
question for me is where such settings should be located in the UI, if
they should be moved from the user preferences to the scene properties
or not. Addons can still put the settings wherever they want.

To me it seems like the GPU switching is more about render at full
power / render with better interactivity, so I would consider adding a
setting like that in the scene properties, rather than a list of all
devices which is more system specific and belongs in the user


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