Forcing Blender Cycles to use GPU

[jrsndl]

Is there an existing issue for this?

• I have searched the existing issues and added correct labels.

Please describe the feature you have in mind and explain what the current shortcomings are?

Blender Cycles using GPU is very useful for fast turnarounds. The speedup is tenfold or more on many scenes.
Forcing Blender to use GPU on renderfarm for Cycles is not strightforward.
I suggest Ayon should support Deadline render submissions with forced GPU.

It seems the workaround is to execute Python script on each render node before render starts with Blender -P command line option.

See long thread on AWS forum.

Suggested implementation?

The ForceGPU.py from the AWS forum post, modded by AWS staff (the autotile addon might be skipped):

import bpy

bpy.context.preferences.addons['cycles'].preferences.compute_device_type = 'CUDA'

#calling get_devices() first will populate the devices list
#otherwise the script might find it empty, even when compatible devices are present
bpy.context.preferences.addons['cycles'].preferences.get_devices()
bpy.context.preferences.addons['cycles'].preferences.devices[0].use= True

bpy.context.scene.cycles.device = 'GPU'

#Use auto tile size to automatically set the tile size
#that better takes advantage of your GPU
bpy.ops.preferences.addon_enable(module="render_auto_tile_size")
bpy.context.scene.ats_settings.is_enabled = True

bpy.ops.render.render(animation=True)

See also the post from reecemuller on Ynput forum.

Describe alternatives you've considered:

No response

[BigRoy]

I assume, on the farm, that Blender still runs the full startup scripts of AYON - right? If so, I think we're better off doing this differently. We could e.g. submit along an environment variable to the farm job:

AYON_BLENDER_CYCLES_FORCE_GPU=1

And have startup logic that if that is set that it forces those addon preferences to be set as the user requested. That way, I don't think we need to change any Deadline-related logic? (And potentially even better; the logic may transfer to other renderfarms?)

If Blender, when rendering on farm does not trigger the usual pipeline startup scripts (like installing AYON Host) then we might need to look into other options, yes.

[jrsndl]

It looks to me that Ayon launch is not connected to deadline cmd. We need to add the -P option to the deadline arguments somehow.

I can mod the deadline blender plugin and add the -P file.py depending on the environment. Maybe The vanila Deadline 10.4 Blender Plugin has no -P render argument, so I think no way around that, anyway.