[Bf-committers] Couple of questions about rendering settings using python scripts and strange GPU performance

[Andrey Chursin]

Hi

I am processing blender file using python script passed in -P cmd argument

I am new to blender so I am not familiar with all bpy
objects/properties. Can you help me with it?

1) How can I get current rendering tile and estimated time in cycles
rendering engine? I know there is render_stats handler, and I even
found function BlenderSession::get_progress in sources, but I am still
puzzled how can I get this info from python script.
2) How can I get list of cameras available?
3) How can I setup active camera for rendering?
4) How can I get/set number of samples when rendering?

And some question about GPU performance

I was rendering first frame from classroom from blender demo
(http://www.blender.org/wp-content/uploads/2015/04/classroom-200x107.png)

I tested it on c4.large AWS virtual machine (2 cores of Intel Xeon
E5-2666 v3) vs g2.8xlarge GPU vm(4 unspecified nvidia GPUs with 1,536
CUDA cores each)

What puzzles me is that 2-core CPU vm renders 2x faster then 4-GPUs machine.

On GPU I was using combined cuda device, and all GPUs was actually
busy(nvidia-smi shows 99% utilization of all 4 GPUs)

I understand that GPU/CPU are not very comparable, but results are
still strange. Is there any specific conditions when GPU actually
works faster then CPU?


-- 
Regards,
Andrey