GPU scaling not as expected with Vray vs Redshift

[Moriah]

@Jassir

Great, thank you so much ! Having the scene will be very useful.
I guess that it is just that the default settings for the production are not that great. The rays per pixel and ray bundle size are too low for some multi-gpu setups. I guess just increasing them to something like 64 or 128 rays per pixel and 256 or 384 ray bundle size will fix the issue (and make the render faster in general). We have a note to bump those defaults for the next SP.
And btw, we have multiple nightly builds with the same V-Ray core version (probably we have to change this). The build number (it is part of the .zip that you download) helps identifying the exact V-Ray build better.

Best,
Blago.

Ok, so i tried what you said, 128 rays per pixel and 384 bundle size… And it is 3.5x SLOWER, also there seems to be a big light difference, i think the GI contribution has gone up for some reason. Percentages seem to be the same too…

Here’s the screen:

You can dl this simple scene here (max 2015): http://s000.tinyupload.com/index.php?file\_id=42805964342919048656

Vray version is 26831

Edit: Installed version 26832, now it spends alot of time in “Compiling kernels..” and it takes 53s with 3 GPUs… still almost 2x slower than default settings.