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

Gottfried Hofmann gottfried at blenderdiplom.com
Sat Nov 5 10:29:47 CET 2016

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 
   - 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.

Cheers and thanks for considering an option to select multiple GPUs, it 
is very much needed indeed.


Gottfried Hofmann
Blender Foundation Certified Trainer

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