Chaos Corona Forum

Chaos Corona for 3ds Max => [Max] I need help! => Topic started by: k.dlugosz on 2023-10-04, 23:46:34

Title: [solved] CPU usage depends on shader, probably displacement. (Ryzen TR3960x)
Post by: k.dlugosz on 2023-10-04, 23:46:34

Hi,

I have upgraded my setup from Ryzen 3900x to TR3960x (which in Corona benchmark is around two times better), and quite fast I have noticed repeating issue.
I run Windows 11 with max 2024 and Corona 10 hotfix 1.

My CPU usage vary on the currently used shader. I am talking about both, interactive and production renders. I usually use Corona Physical Material and I of course use some legacy, but converted, shaders with Corona Bitmaps. This problem appears between two Physical Materials in this case, but it also occurs with legacy ones.

I attach the screenshots of the shaders. Those are not very complex ones, those are fabrics, but usually with the displacement. On trail and error I have found that removing displacement solves the CPU usage clamp, and it goes up to 100%, with only displacement plugged in - same results, usage clamped.

Shader number 1. has the lowest displacement value in size, and renders with 100% CPU usage. Shader number 2 and 3 have more intense displacement and goes respectively 50% and 65% CPU usage on both interactive and production. I Do use 2 or 3 px displacement resolution in scene settings.

Is this case a known way the renderer works, or am I missing something?

Title: Re: CPU usage depends on shader, probably displacement. (Ryzen TR3960x)
Post by: romullus on 2023-10-05, 10:25:26

There is a bug in Corona 10 where triplanar maps can cause significant slowdown. This has been fixed and the hotfix should be released very soon.

Title: Re: CPU usage depends on shader, probably displacement. (Ryzen TR3960x)
Post by: Avi on 2023-10-05, 12:03:53

Hi,

It seems like you are using triplanar textures in your shaders and recently, there were some reports about performance drop when using triplanar textures in Corona. The fix is already present in Corona 11 DB which you can try it and see if it solves your issue.

You can download Corona 11 DB from here: https://forum.corona-renderer.com/index.php?topic=40442.0

Note: The daily builds are the newest, experimental versions of Corona Renderer intended mainly for testing purposes and to showcase the recently added features. They contain the latest bug fixes but are not guaranteed to be stable, and in some cases can even damage scene files.

Check this link to know more about it: https://support.chaos.com/hc/en-us/articles/4528206493329-Corona-for-3ds-Max-Daily-Builds-

Title: Re: CPU usage depends on shader, probably displacement. (Ryzen TR3960x)
Post by: k.dlugosz on 2023-10-05, 12:34:08

thanks guys for suggestions. Just curious if I can handle both versions of Corona at the same time? Use 11DB in problematic scene and 10 in others?

Title: Re: CPU usage depends on shader, probably displacement. (Ryzen TR3960x)
Post by: Avi on 2023-10-05, 13:08:55

You can use multi loaders for this.

https://support.chaos.com/hc/en-us/articles/4528349126417-How-to-start-3ds-Max-with-a-specific-version-of-Corona-using-multiloaders-with-Corona-5-and-newer-

Title: Re: CPU usage depends on shader, probably displacement. (Ryzen TR3960x)
Post by: TomG on 2023-10-05, 13:42:19

BTW the hotfix for Corona 10 that addresses the Triplanar slowdown is now out:
https://forum.corona-renderer.com/index.php?topic=41081.0

(so you won't have to use a daily build to access that fix any more :) )

Title: Re: CPU usage depends on shader, probably displacement. (Ryzen TR3960x)
Post by: k.dlugosz on 2023-10-05, 13:50:32

I haven't known that you have started "hotfix on demand" feature xD Thanks!


edit after update :

yeah this resolved the issue.

Title: Re: CPU usage depends on shader, probably displacement. (Ryzen TR3960x)
Post by: TomG on 2023-10-05, 14:10:23

Hahhaha! You are welcome :)