Cinema4D Vram usage

[Mikla]

Hi there,

I have noticed something weird with the way Cinema4D/Octane uses Vram.

I have dual rtx 3080. Tested this both in r17 and r21. RTX on and Off.

When monitoring Vram usage with GPUz I see about 2.5gb used by windows which is normal. Then I fire up C4D which raises the Vram usage to 2.7GB and put a cube in the scene and render it to LV.

The Vram usage goes up to 5GB while Octane shows the Vram used: 1GB. There's 1.3GB of Vram that is probably used by C4D but I don't know how. This can also be seen in the Octane's GPU tab.

The unavailable Vram doubles when I hit render in some scenes. From 2 gb to 4 gb sometimes. This unavailable memory increase is most likely created by either C4D or Octane and I cant do anything about it as it isn't shown in texture or geometry section.

Is this a known phenomenon? Is there any way to mitigate this extra unavailable memory?

Thanks.

[bepeg4d]

Hi,
weird

I suppose that you don’t have any other application running while rendering

Please go to c4d menu Script or Extensions/Console, (Shift+F10), and share a complete screenshot of the panel, thanks.

Please, also go to c4doctane Settings/Devices panel, press the Device Settings button, and share a complete screenshot of both panels, thanks.

Finally please, also download and run GPU-Z:
https://www.techpowerup.com/gpuz/
And share a screenshot from the Graphics Card tab, for all the available Nvidia GPUs, thanks:


It would be nice to see also some screenshots from GPU-Z Sensors tab while rendering.

ciao Beppe

[Mikla]

Hi Beppe;

Sorry for the delay. Here are the screenshots:

Idle system no Cinema4d instance is running:

C4D open with empty scene:

Octane rendering a Cube:

Octane rendering a complex scene:

ciao

[bepeg4d]

Hi,
GPU-Z shows 9869MB of memory used in the complex scene, so it is too high for your GPUs.
Roughly you should have max ~7.5GB of available VRAM, so it means that ~3GB of the scene has been moved to Out-of-Core, and the speed has dropped of %20%, isn’t it?

ciao Beppe

[Mikla]

Hi Beppe,

Here's the stats from the complex scene. It seems i'm not using ooc at all.

Best.

[dynaraton]

The Unavailable Memory has grown to on my RTX Titans as much as 8GB on my 24GB cards. I don't know why it does this but also shrinks down again when I start filling up my VRAM on some scenes. Sometimes it goes down a little, sometimes a lot.
Also when NvLink and/or Out-Of-Core is being used, that gray Unavailable memory bar will bounce up and down. What you are experiencing is what I have been experiencing for the past two years using Octane. I also wish there was a way to clamp down the Unavailable memory.

[Mikla]

I know, its frustrating because something (windows?) gobbles up the vram on percantage basis. So when I render the same scene with an old 980ti or rtx 3080 i end up with same free vram...

I read somewhere that Red Shift reserving vram at the start? Could this also be done with Octane?

[abdalabrothers]

isn't it possible that we could put a single low end gpu on the first slot, to dedicate it to windows/monitor stuff, and leave all the multi gpu processing aside from the system?
must have some way to bypass this issue

[dynaraton]

isn't it possible that we could put a single low end gpu on the first slot, to dedicate it to windows/monitor stuff, and leave all the multi gpu processing aside from the system?
must have some way to bypass this issue

Apparently so..but on the high end video cards.
I just found out that I can Enable Tesla Compute Cluster (TCC) mode on my RTX Titans. I could use all 24GB just for rendering. Problem is that it cannot be connected to display. I bought 2 Titans for NvLink memory pooling rendering so that plan won't work out unless I add a third cheap card for display. I don't even know if there will be issues with TCC mode on with Octane. ?
TCC is only available for RTX Titans and Quadro cards. I am not sure about the new RTX30..'s. Knowing NVidia, they will give this option to you only if you pay for high dollar cards.

[Mikla]

TCC isn't supported by 30 series cards at this point as far as I know. Although it's purely driver related I don't think Nvidia would let the gamer series cards cannibalize the pro segment.