Iray VRam usage issue

PixelReaper

Hi,

It appears that Iray is using only half of my VRam for rendering.

My config is : GTX 1660 ti - 6Go VRAM ; i7 - 8700K 3.70 Ghz ; 64Go RAM

When I try to render a scene, I don't know why but once I reach a limit of 3Go video memory I can't load it ...  render stops immediately and I have a black image.

For animated sequence, if the frame is less that 3Go it render properly but if not, daz crash and I have a fatal error message.

My Nvidia Drivers are up to date. I tried to look for a VRam limitation option in DAZ but can't find it.

For the moment, I'm dealing with scene optimiser for keep my scene under 3Go but it would be cool if I could use all my VRAM.

For info, I don't have this problem with blender... so I don't think the probleme is coming from my graphic card.

 

 

 

PerttiA

First of all, windows reserves some of the VRAM for itself, rendering IRAY on GTX card uses more VRAM since the missing RTX functions must be replaced in software, these are all something that you cannot see in the log.

Download GPU-Z (https://www.techpowerup.com/gpuz/) to see what's really going on.

ebergerly

How do you know that it's only using 3GB of your GPU VRAM? Where do you get that info? Are you looking at Task Manager in Windows 10, at the "Dedicated GPU Memory"? That should show you total VRAM usage vs total installed VRAM on the GPU. 

Yes, Windows doesn't allow any individual process to grab all the VRAM (one of its jobs is allocating hardware among all the processes, and making sure there's some available if another process needs it), but that wouldn't account for 3GB out of 6GB.

Also, in Task Manager you can see which individual processes are using GPU memory. That's important because it shows you VRAM usage (and a lot of other stuff) BY PROCESS, which most or all other reporting software doesn't AFAIK. 

If it was me I'd be watching Task Manager to see what the individual processes are doing.  

PixelReaper

Thanks I can see that daz is actually using 5.6Go of my VRAM! I guess the rest is for windows can keep running other apps.

I thought that in the render window, when daz is compiling the scene before rendering, the iray statistics memory consumption was indicating how much vram the scene will need to render but it's not very accurate...

Thanks for your help anyway :)

PerttiA

PixelReaper said:

Thanks I can see that daz is actually using 5.6Go of my VRAM! I guess the rest is for windows can keep running other apps.

I thought that in the render window, when daz is compiling the scene before rendering, the iray statistics memory consumption was indicating how much vram the scene will need to render but it's not very accurate...

Thanks for your help anyway :)

That window only tells you how much memory will the textures, geometry, etc. use in the rendering process, but it doesn't tell you how much VRAM DAZ has already reserved.

TheMysteryIsThePoint

If you're using Optix, there's also a data structure that needs to be stored on the GPU as well. I don't know about IRay, but for Cycles/Optix it can be very large. The point being that it's not just about geometry and textures...

PerttiA

Just did a little test by starting the computer, opening DS, loading a G8F character (with clothes and hair) and rendering it, while monitoring the memory usage with GPU-Z, (W7 Ultimate, RTX2070Super, 64GB RAM, texture shaded viewport)

After Windows start, RAM 4.4GB/VRAM 200MB
DS started, RAM 5.0GB/VRAM 370MB
Character loaded, RAM 9.7GB/VRAM 422MB
Rendering, RAM 11.1GB/VRAM 2948MB
After saving/closing rendering window, RAM 9.9GB/VRAM 2560MB (Interesting...)
After closing DS, RAM 4.6GB/VRAM 200MB

The log reported 2.024GiB as memory load for the render (1.976GB)

It looks almost like the stuff DS reports in the log is left in GPU memory after the first render. I did a couple of renders and the RAM/VRAM loads stayed at the same level with the first render, but the VRAM load didn't go below 2560MB;s until I closed DS.