CPU fallback (Update and partial workaround)
reserv888
Posts: 1,143
What triggers the CPU Fallback?
Is it DAZ Studio or the graphics card?
I get a lot of CPU Fallbacks when there seems to be no reason for it.
(Graphics card is NVIDIA Geforce RTX 2080 Ti).
Post edited by reserv888 on
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I would guess you are running out of memory on your GPU.
Try to look in your log file Help > troubleshooting > Logfile
Than you felis.
This happens even in very simple scenes, like - character, hair, clothes - and nothing more.
The graphics card has 11 GB of VRAM.
From that 11GB, about 8GB is available for Iray rendering.
It doesn't need but one badly created item, that has high vertex count, high SubD, large textures/maps with bad UV mapping, maybe all together.
Usually the culprit is the size of the textures (pixel size of the textures/maps), but strand based hair is also known to eat ridiculous amounts of resources.
If my computer, which I've paid a substantial amount for, isn't good enough even for simple renders in DAZ Studio, I will seriously consider a new hobby.
As I said, it isn't about being 'simple', it's about the items that are loaded in the scene. One needs to learn how to identify the items that are problematic and either stop using them or learn how to fix them (if they are fixable)
Maybe you know how the fallback works. When the CPU fallback kicks in, is it for the rest of render or just temporarily?
Fallback happens when the GPU runs out of VRAM and that's it for the duration of the render, the scene is too big for the GPU and you need to figure out what to do to get the VRAM usage down.
1. Size of textures and maps.
Does not matter what the size of the imagefile on disk is, as the images are handled uncompressed when loaded to any program.
One 8192x8192x24bit image will take 192MB's of memory when loaded to a surface, if that surface has same size maps for whatever, the memory usage is multiplied with the number of images. A surface with a texture and four maps at 8192x8192x24bit, will take almost a gigabyte of memory.
Iray does use compression, but the amount depends on the settings you use. The default settings take memory usage down to about a half, so if an image takes 192MB's of RAM, it needs 96MB's of VRAM while rendering Iray on the GPU, and that is just one image.
2. High SubD values.
Some products are delivered with SubD 4 (even 5) as default, which most of the times is just waste of resources.
DS is not a game and high SubD's are not the "Show me everything and the kitchen sink" from the gaming world.
Every step of SubD quadruples the face count of the mesh from the previous value after which the geometry needs more VRAM in Iray rendering.
For full body scenes having "Render SubD Level" at 2 or even at 1 is ok - Don't believe, try and see.
If one is making portrait renders, higher SubD's can give more detailed skin if supported by the active HD morphs, but then one can remove or hide everything that's not visible in the camera, including (hiding) parts of the figure being rendered.
In my tests having "Render SubD Level" at 4 for a G8 figure, shot the VRAM consumption of the geometry to significant values.
3. Bad UV mapping.
If just a portion of an image is used on an item, the memory consumption of the image is still for the whole (uncompressed) image.
I have seen examples, where the texture and four maps attached to a surface were all 8192x8192px at 24bit, using just a tad under a gigabyte of RAM.
When checking the area that was actually used from those images, they could have been redone with exactly the same level of detail and the resulting images would have only required 20 megabytes of RAM - That has so far been the worse case I have seen, but having 40-60% of the space on the images used for nothing, is just 'normal'
Fixing badly made UV's is a problem that's very hard and time consuming to fix, usually just easier to forget that product.
4. High vertex count
The Genesis 1-8.1 figures are pretty good as far as the vertex count is concerned, unless the creator of a character has pumped up the value of SubD to ridiculous values.
Props, hair and clothing is another thing completely. I have seen little (insignificant) trinkets with vertex count in close to million (= abut the same as fifteen G8 figures), which is just insane for something the size of ones fingernail
Also a problem that's very hard and time consuming to fix, usually just easier to forget that product.
Thanks a lot PerttiA for the information! (I have copied it and saved it).
After some monitoring with TechPowers GPU-Z I've found that the CPU fallback, to my understanding, has nothing to do with the limit of VRAM.
The fallback occurs even below 50% of VRAM max usage.
(What i haven't said is in this entry before is that when the fallback occurs, I get a Black Screen. Hard reboot needed.
The GPU-Z monitoring program shows that the CPU temp goes from 70 degrees Celsius to 100 degrees, in about 7 seconds when the fallback occurs.)
(My CPU is Intel I7 11700, 2,50 GHz, 8 cores)
What does your log say? (Help->Troubleshooting->View Log File)
Do not copy the text to the message area, attach it as a file to your post with "Attach a file" above the "Post Comment" button.
As you have 11th gen Intel processor, this may be relevant
https://www.daz3d.com/forums/discussion/comment/6874141/#Comment_6874141
I have already tried that, but thanks for the tip!
Attached to this message is the DAZ log from the latest black screen.
(The VRAM was used to less than 50% when the CPU fallback was triggered. Then the CPU overheated in a matter of seconds.)
What version of drivers are you using?
Have you tried to update drivers?
If you refer to the drivers to the graphics card, it is the latest one. NVIDIA has two versions of the drivers, one for gaming, and one for stability. I have tried both. No major difference, if any.
If you had included the log from the start of that session, there might be things explaining what's happening.
Now it only says "Unknown error"
Ok, I'll be back.
Here is a log file from the beginning of a session.
And another log file. From a fresh black screen a minute ago.
You have nested libraries inside Content directory D:/DAZ STUDIO/DAZ CONTENT/My Library;
D:/DAZ STUDIO/DAZ CONTENT/My Library/content
D:/DAZ STUDIO/DAZ CONTENT/My Library/Dreamlight_Doomed/Poser
D:/DAZ STUDIO/DAZ CONTENT/My Library/My Library
D:/DAZ STUDIO/DAZ CONTENT/My Library/Runtime
DS does not like nested Content Libraries, you need to move those libraries out of D:/DAZ STUDIO/DAZ CONTENT/My Library
You have Reality installed and apart of it having problems, it may interfere - Remove
"Existing directory encountered while adding a content folder: C:/Users/Per/Documents/DAZ 3D/Studio4/Reality-Add-ons"
"Warning: Exception in Reality's check for updates "
You have "LAMH2Iray Catalyzer evaluation" installed and not working - Remove
These are not causing your renders to fail, but if nothing else, they will slow down loading of G8F;
E:/DAZ STUDIO/DAZ CONTENT/My Library/data/DAZ 3D/Genesis 8/Female/Morphs/Hinkypunk/Kinsley/KinsleyBody.dsf (24,0): Illegal new-line in string
277 warnings for "Formula output property not found", "Formula target property not found", "Unsupported formula" and "Parent for modifier not found"
You need to update at least "Growing Up" and "AutoFaceEnhancer" (AFE alone is causing 215 warnings)
The way the rendering drops to CPU after having done thousands of iterations already suggests there could be something wrong with your card
Thanks a lot PerttiA for helping me!
The nested libraries makes me puzzled.
"You have nested libraries inside Content directory D:/DAZ STUDIO/DAZ CONTENT/My Library;
D:/DAZ STUDIO/DAZ CONTENT/My Library/content
D:/DAZ STUDIO/DAZ CONTENT/My Library/Dreamlight_Doomed/Poser
D:/DAZ STUDIO/DAZ CONTENT/My Library/My Library
D:/DAZ STUDIO/DAZ CONTENT/My Library/Runtime"
The libraries simply doesn't exist. (see image). I have no idea what those lines in the log file refers to. (I have the librariies, but on another hard drive).
Apart from that, I have:
- removed Reality
- removed LAMH2Iray Catalyzer
- removed and reinstalled Kingsley
- removed and reinstalled AutoFace Enhancer
(Have not tested anything yet.)
Which content directories do ypu have set in Content Directory Manager?
Expand everything like in the attached screenshot
Here is a screenshot of the Content Directory Manager.
Just like the log says, you have those nested Content Directories listed under "Poser Formats" - Remove
After some cleaning up, the Content Directory Manager looks like this (see image). I don't know if I should delete more.
The computer still gets Black Screens but the DAZ log looks different (see image). It is "cleaner". No warnings or anything.
I am not sure if this is relevant but the CPU overheating is gone. No sign of it in TechPowerUp GPU-Z monitoring program.
Still get Black Screens though.
Have you tried older drivers
https://www.daz3d.com/forums/discussion/529616/daz-studio-pro-4-20-0-x-nvidia-iray#latest
I'm using 471.41
I changed the driver to 471.41. Still get the black screens.
The rendering in the last log didn't drop to CPU, or at least had not logged it.
Are you rendering in the viewport or to separate window, and do you use texture shaded preview or Iray preview?
I have had CPU fall backs (and black screens) after the last one I posted.
In the logs I have posted here in this thread, it is always renders in separate window. Never viewport renders.
(When I make viewport Iray renders and switch textures, like when i want to test different hair colour options, I get black screens VERY often. Since I can avoid it by using texture shaded preview when i change colour, I have ignored that issue. For now).
I use both texture shaded preview and Iray preview, but I never have Iray preview on while making a real render in a separate window.
Grasping straws here, but a few things to try, based on previous threads with problems...
Have you installed the (free) Octane plugin? - Remove
Have you installed the Nvidia vMaterials 1.7/2.0? - Remove
What happens if you load the Genesis 8 Basic Female and try to render her as she is, without anything else in the scene?
How long have you had the 3090, can it be dirty and overheating in areas that are not monitored?
Have you tried any stress tests? Check this out;
https://www.daz3d.com/forums/discussion/comment/6215226/#Comment_6215226
(The heureka moment)
How big is your PSU?
Have you tried underclocking the GPU?
If your CPU is going up to 100 degrees C, you don't have adequate cooling in your computer.