GPU Memory Usage and Error saving tile to file - Cycles-X

Support Technical Support
1

I have two problems that I have tried finding answers to in multiple searches and nothing I have found works.

First my machine:

AMD Ryzen 7 3700x

RTX 2070 Super

32 GB RAM

Windows 10

K Cycles-X

My Scene:

BA Example
BA Example629×725 42.1 KB

I made a swing with the following specs, but this applies to every file I have tried more or less complex: 1,127,053 verts
Render size: 4350*5000px

My two issues:

The first issue is rendering with my gpu in standard cycles-x, no tiling. I don’t know where the cutoff point is, but if I render it at half the resolution above, I get the following memory usage which you can see is GPU only (28.57 seconds to render the image):

BA Cycles X half Res
BA Cycles X half Res830×740 103 KB

If I render at the full resolution above, it will automatically use the same amount of memory in the shared gpu memory (which I believe is just using some of my system ram as overflow), rather than filing the video card, and basically it takes forever to render: It took 7:17 just to do the first 128 samples. I resort to killing the program with the task manager also when it does this because hitting cancel freezes it up for 5 minutes or more.

BA Cycles X Full Res
BA Cycles X Full Res840×818 114 KB

If I open the same scene, same settings in 2.93 and render with auto tile sizing in K-cycles, I get the following usage at full resolution (full render time including compositing at 1:33):

BA 2.93 Render Example
BA 2.93 Render Example2615×1889 641 KB

At the moment this forces me to render in 2.93. Does anyone know why cycles x is shifting to shared memory instead of using the gpu memory?

My second issue is directly related to this problem. I just realized that Cycles-X has tile options again, so I did a test setting up tiling to see if it would take care of the memory problem. It worked, memory usage was correct! But the render fails every time no matter what tile size I use for the same reason: Error writing tile to file after the first tile finishes. Some people with this error said change the tile size. I did, multiple times, that didn’t work. Some said it was the location of the temp folder being messed up, so I fixed that, still failed. tried to save it to a location other than the temp folder. Still failed. So now, even though it will not go memory crazy at high resolution, it is still unusable to render my files. And my client requested the resolution, so I can’t drop it.

Any advice on these two issues would be really appreciated. I hope I have explained it well.

2

Since Cycles X (Blender 3.0) tiling works differently.
See section “Tiles & Memory Usage” in release notes:

https://wiki.blender.org/wiki/Reference/Release_Notes/3.0/Cycles

  1. I’m not sure how K-Cycles is different, so you might consider dropping it for vanilla Cycles until changes made during Cycles X project are stabilized well enough in Blender.

  2. Redownload and upgrade Blender to stable version 3.0.1 ← this is corrective release to this → 3.0.0 It has many bugfixes, and AFAIK there was one or two about tiling.

  3. Update GPU drivers.

  4. Beware that rendering passes take more memory after Cycles X. Sometimes waaaaaaay more. So render only beauty pass without AOVs, Cryptomattes and multiple passes.

Check if these 4 changes anything.

As for the GPU rendering and VRAM usage I can’t help much as I still wait for HIP on Linux support in Cycles, so my GPUs cannot render anything since 3.0.
CPU rendering however works. I checked it on a renders with almost 20 000 x 12 000 px in size.

If you will get your GPU to work properly you will need to rethink your rendering optimization strategy.