Cycles GPU raytracing makes computer unresponsive

Can’t recall that this has been as bad as in the current build.
Raytracing is completely hogging the entire computer for the time of the render (and, btw, it starts from scratch for any viewport capture).
Computer becomes sluggish, almost unusable, until render finishes.
Rhino 6 (6.23.20055.11282, 2020-02-24)
AMD Radeon Pro Vega 48 (8GB)

Thank you!

When you start a new viewport capture do you use the dashed command, and does the panel on the left change size? If it does the viewport will change size, which triggers a restart. Changed size also means differences between vp and capture settings.

Further there has between 6.21 and 6.22 only one fix for Raytraced, nothing else has changed since.

thank you, no i am using the command without the dash but will try the pull down menu. i don’t think there is a change in viewport size.

the main issue, however, is not the rerendering but the complete hogging of the computer. the CPU usage is only 20%, but the GPU runs at 100% non-stop.

i tried switching cycles to CPU but it still uses the GPU, at least according to the activity monitor.

Did you toggle the viewport to say Wireframe then back to Raytraced after making the change?

Tried now and yes, this helps. Rendering is now done on CPU, using all cores. Computer stays responsive.
So it seems the issue is with Rhino’s usage of the GPU?
Is the dev. team aware of it and is there any solution being worked on?
Thank you!

I am using the exact VP size. I noticed that the “Transparent Background” might be the reason. Even if there is no actual transparent background (e.g. entire image is filled with objects), this does seem to trigger a re-rendering of the scene.
In any case, would be very desirable for this not to happen.

This is a common problem when using GPU-based rendering when using the only GPU on your machine can do this. The best I can advise is to use CPU on the viewport and GPU for when you want to do an actual render.

If there is any setting different in the view capture dialog from what you have in the regular settings there will be a complete rererender.

Hi Nathan, which should I be using on a MBP with Radeon Pro GPU ? What are best settings for using Cycles Raytraced ? screenshot attached

Don’t use the Intel one, that is in my experience worse than the Radeon Pro. That said I don’t have much experience with neither the Intel GPU nor the AMD GPU on OpenCL on the Mac, so can’t really say one way ore another.

thanks, so would the OpenCL option be better than switching to just use the CPU ? I know CUDA is not an option, just wondered which is best ?

Well, best is to try them both and see which one works best for you.

oh right, just thought you might know which is best option for Raytraced engine on Mac ?