Odd GPU performance for V-ray

[mahmoodn]

Hi

With 3ds Max 2018 and the V-ray 3.60, I ran a simple rendering job where the frame size is HD (1920x1080). On a Sandybridge 8-core cpu (with hyperthreading it is 16) which is rather an old CPU, the redering took 16 minutes.

 

I also, ran that on a PNY Quadro M2000 and I checked that the GPU is fully loaded. It took 13 minutes to finish the job! I set the renderer to V-ray RT.

 

So, does that comparison make sense?

[Francisco Penaloza]

Well it depends, your CPU is very powerful and your GPU is on the small size so do not expect big differences.

 

Also, remember that it also depends on your scene size you may run out of memory with your GPU in that case, the only way to go is CPU.

 

Now comparing only rendering time is not everything, final output size, quality and as a mentioned earlier size of your scene should be considered when you compare GPU Vs CPU rendering.

[mahmoodn]

Well an 8-core (16 threads) sandybridge should not be more powerful than a Maxwell GPU with 700 cuda cores for these applications.

The memory usage of the GPU is about 500MB according to the GPU-Z program and the M2000 has 4GB of memory.

 

I am not a 3ds expert. Can you give me a scenario for a better test? Maybe by tweaking the settings, the CPU loose! How can I find and check the output size and quality?

[Francisco Penaloza]

Well an 8-core (16 threads) sandybridge should not be more powerful than a Maxwell GPU with 700 cuda cores for these applications.

The memory usage of the GPU is about 500MB according to the GPU-Z program and the M2000 has 4GB of memory.

 

I am not a 3ds expert. Can you give me a scenario for a better test? Maybe by tweaking the settings, the CPU loose! How can I find and check the output size and quality?

 

Here

https://docs.chaosgroup.com/display/VRAY3MAX/V-Ray+for+3ds+Max+Help

[mahmoodn]

One thing that I can not find the reason is that, when I set the renderer to V-ray ADV, the job is put on the CPU *only*. However, if I use V-ray RT, I can choose between CPU and GPU.

 

Is that normal? Why ADV doesn't use GPU?

[jackbird]

One thing that I can not find the reason is that, when I set the renderer to V-ray ADV, the job is put on the CPU *only*. However, if I use V-ray RT, I can choose between CPU and GPU.

 

Is that normal? Why ADV doesn't use GPU?

 

Yes, that's the difference between ADV and RT. The non-RT version has broader support for features that don't have CUDA implementations. Hybrid CPU/GPU RT rendering is a fairly recent (3.5? 3.6?) addition to RT.