Hybrid Vray GPU?CPU

[savage309]

So does this mean there is one code base going forward OR that there still will be two, just that we can now run what use to be the GPU code on CPU?

I'm thinking it's just that the GPU version now runs on CPU yeah?

Either way it's exciting but just want some clarification as my quick read of the FXguide article didn't really seem to say.

We have made the CPU behave as a regular CUDA device, so it will be able to execute the V-Ray GPU code.

This sounds exciting! I just tried the nightly of Vray for Max from 3 days ago to test the new hybrid CUDA rendering but most of the time when I start rendering with CUDA I get this error:

error: Error 700 while initializing context for device GeForce GTX 980! Device will not be used for rendering!
error: There is no device supporting at least CUDA 2.0!
warning: initDevices() failed. Please check that your system has compatible GPU devices installed.

When I render with the c++/CPU device I don't get this error but my GPU doesn't get used. I reinstalled the nightly two times with no change.

It seems like a problem with your CUDA GPU. Very hard to say from that log. As first step, make sure to use NVIDIA driver version 37X. Drivers after 380 are known to cause troubles at the moment.

Best,
Blago.

[Donfarese]

I'm using vray_adv_35004_max2017_x64_27377, I don't see this option to select a CPU?

[savage309]

I'm using vray_adv_35004_max2017_x64_27377, I don't see this option to select a CPU?

It is not in the stable nightlies ..

Best,
Blago.

[Alex_M]

As first step, make sure to use NVIDIA driver version 37X. Drivers after 380 are known to cause troubles at the moment.

Best,
Blago.

That was it, thanks!

By the way, I think there's a bug in the nightly for Max. When rendering with RT CUDA as production renderer, the elapsed render time visible in VFB's image history is wrong. It seems that it gets compounded with each render. So if the 1st render takes 5 min. and the 2nd render takes 10 min, the elapsed time for the 2nd render will show as 15 min instead of 10 min. While the image is being rendered though, the progress bar at the bottom shows the correct elapsed time. This is with vray_adv_35701_max2016_x64_27396.

Anyways, my initial tests show 15-20% speed increase in simple interior scenes by including my CPU in the rendering. Obviously this will vary with different hardware configurations. Another observation is that the DOF effects in the GPU+CPU renders don't match with that in the pure GPU renders. It's a bit more blurry in the pure GPU render. Also the edges of objects that are in focus are a tad bit more defined in the hybrid rendering.

[Donfarese]

It is not in the stable nightlies ..

Best,
Blago.

That's the only nightlies I see, how do I get access to the rest? Other than that it shows me Blenders nightlies for some reason, I don't even use blender.

[Dentzz]

Blago this sounds very cool, can't wait to get a chance to try it out once it is in vray modo. Definitely looking forward to see future improvements for Vray GPU rendering and hopefully full parity with CPU rendering.

[savage309]

The DOF issue is a known bug that we will fix. Thanks for sharing feedback for the speed increase, looks lke it is working well
For access to the internal nightlies you have to write to sales@chaosgroup.com.

Best,
Blago.