Cinema 4d and Octane strange Vram utilization

[85cibi]

Dear all,

i really hope that someone could help me with this problem.
I have created a simple scene to make a test with my 2xQuadro A5000 24gb Vram machine using Cinema 4d R25 and Octane 2021.1 R2.

I put some heavy trees inside my empty scene and scattered them both with Octane scatter and Surfacespread.
They give me more or less the same result, about 13.1/2 gb of Vram utilization. The scene has about 35 million polygons, so not so big for our standard. With cpu render engine we usually have 50-70 million polygon scene without any problem.
Anyway, the strange thing (for me) is that with one card i have 2.2gb unavailable and with the second one i have 7.9gb of unavailable.
isn't that crazy? Please find the images attached.

Another strange thing is that if I use a single video card at a time, the available memory always remains the same, which is ONLY 2.9 gb.
As is possible with 24gb of Vram, if I use 13gb, I should have at least 7-8 gb free considering that 3-4gb can be taken from the system.

In this way for us is impossibile to manage any arch-viz project with more than 20-25 million polygons considering at least 3-4 gb of textures without using Out of Core.
And, honestly, with these kind of video cards I was hoping to be able to manage without any problem the projects that I previously managed in CPU.

I really hope that someone could help me with this big problem.
Thank you so much

[jayroth2020]

Your VRAM allocation is limited by the active GPU with the least amount of VRAM on board. If you have a mix of different VRAM sizes due to different GPU card models, you would see results like you describe.

[Mikla]

Octane and vram utilization is always a mystery to me. You can find my own topic regarding this here:
viewtopic.php?f=30&t=76945

Other GPU renderers "reserve" a big chunk of vram at the c4d startup so you always have more vram available to you when you are rendering. Maybe same can be implemented to Octane.

[bepeg4d]

Please share another screenshot similar to this:


Do you have other applications running like Chrome or Adobe apps?

ciao,
Beppe

[85cibi]

Hi all,

just made a new test and i attached also the screenshot of nvidia control panel.
Also for me is quite a mistery of how Octane and Cinema 4d use the Vram.


At the base of it all I hoped that using some of the best video cards on the market, it was possible to manage any type of scene in Cinema 4d.
To get to saturate 128gb of ram with cpu render engines I had to go beyond 90mln of polygons.

Thank you

[bepeg4d]

Hi,
if you have 2x GPUs and 2x monitors, better to connect one monitor per GPU.
In this way, the available VRAM is the same... probably 3GB per GPU.
Then enable the Priority for both GPUs, and set the Priority popup to LOW, since HIGH means no priority.

The GPU with less VRAM defines the limit of the system, since the whole scene must be completely loaded in each GPU.
Also note that RTX acceleration is increasing the VRAM consumption for geometry.

ciao,
Beppe

[SSmolak]

I noticed too that Octane can be VRam hungry. Try to turn off all viewport enhancements like AA, transparency and disable viewport textures at all. It can sometimes free nice amount of VRam.