Iray large scenes get rendered with CPU instead of GPU

Illidanstorm

Whenever I have a large scene, DAZ3D is rendering with the CPU instead of the GPU, even though CPU rendering is off.

The log is saying this:

2018-07-14 19:22:09.665 Iray INFO - module:category(IRAY:RENDER):   1.0   IRAY   rend info : Rendering with 1 device(s):

2018-07-14 19:22:09.665 Iray INFO - module:category(IRAY:RENDER):   1.0   IRAY   rend info : CUDA device 0 (GeForce GTX 1080 Ti)

2018-07-14 19:22:09.665 Iray INFO - module:category(IRAY:RENDER):   1.0   IRAY   rend info : Rendering...

2018-07-14 19:22:09.665 Iray VERBOSE - module:category(IRAY:RENDER):   1.2   IRAY   rend progr: CUDA device 0 (GeForce GTX 1080 Ti): Processing scene...

2018-07-14 19:22:09.933 Iray VERBOSE - module:category(IRAY:RENDER):   1.4   IRAY   rend stat : Geometry memory consumption: 990.843 MiB (device 0), 0 B (host)

2018-07-14 19:22:09.941 WARNING: dzneuraymgr.cpp(307): Iray ERROR - module:category(IRAY:RENDER):   1.4   IRAY   rend error: OptiX Prime error (Device rtpModelUpdate TL): Unknown error (Function "_rtpModelUpdate" caught exception: Encountered a CUDA error: cudaMalloc(&ptr, size) returned (2): out of memory, [15466617])

2018-07-14 19:22:09.941 WARNING: dzneuraymgr.cpp(307): Iray ERROR - module:category(IRAY:RENDER):   1.2   IRAY   rend error: CUDA device 0 (GeForce GTX 1080 Ti): Scene setup failed

2018-07-14 19:22:09.941 WARNING: dzneuraymgr.cpp(307): Iray ERROR - module:category(IRAY:RENDER):   1.2   IRAY   rend error: CUDA device 0 (GeForce GTX 1080 Ti): Device failed while rendering

2018-07-14 19:22:09.942 WARNING: dzneuraymgr.cpp(307): Iray WARNING - module:category(IRAY:RENDER):   1.2   IRAY   rend warn : All available GPUs failed.

2018-07-14 19:22:09.942 Iray INFO - module:category(IRAY:RENDER):   1.2   IRAY   rend info : Falling back to CPU rendering.

2018-07-14 19:22:09.942 WARNING: dzneuraymgr.cpp(307): Iray ERROR - module:category(IRAY:RENDER):   1.2   IRAY   rend error: All workers failed: aborting render

2018-07-14 19:22:09.943 Iray INFO - module:category(IRAY:RENDER):   1.0   IRAY   rend info : CPU: using 16 cores for rendering

2018-07-14 19:22:09.944 Iray INFO - module:category(IRAY:RENDER):   1.0   IRAY   rend info : Rendering with 1 device(s):

2018-07-14 19:22:09.945 Iray INFO - module:category(IRAY:RENDER):   1.0   IRAY   rend info : CPU

2018-07-14 19:22:09.945 Iray INFO - module:category(IRAY:RENDER):   1.0   IRAY   rend info : Rendering...

2018-07-14 19:22:09.945 Iray VERBOSE - module:category(IRAY:RENDER):   1.2   IRAY   rend progr: CPU: Processing scene...

2018-07-14 19:25:47.318 Iray INFO - module:category(IRAY:RENDER):   1.4   IRAY   rend info : Initializing light hierarchy.

2018-07-14 19:25:47.325 Iray INFO - module:category(IRAY:RENDER):   1.4   IRAY   rend info : Light hierarchy initialization took 0.00s

2018-07-14 19:25:48.392 Iray VERBOSE - module:category(IRAY:RENDER):   1.4   IRAY   rend stat : Native CPU code generated in 0.000257s

2018-07-14 19:25:52.259 Iray INFO - module:category(IRAY:RENDER):   1.2   IRAY   rend info : CPU: Scene processed in 222.314s

2018-07-14 19:25:52.275 Iray INFO - module:category(IRAY:RENDER):   1.2   IRAY   rend info : CPU: Allocated 39.5515 MiB for frame buffer

2018-07-14 19:25:54.671 Iray INFO - module:category(IRAY:RENDER):   1.2   IRAY   rend info : Allocating 1 layer frame buffer

2018-07-14 19:25:54.750 Iray INFO - module:category(IRAY:RENDER):   1.0   IRAY   rend info : Received update to 00001 iterations after 225.083s.

2018-07-14 19:25:57.173 Iray INFO - module:category(IRAY:RENDER):   1.0   IRAY   rend info : Received update to 00002 iterations after 227.505s.

2018-07-14 19:26:01.986 Iray INFO - module:category(IRAY:RENDER):   1.0   IRAY   rend info : Received update to 00004 iterations after 232.318s.

2018-07-14 19:26:11.504 Iray INFO - module:category(IRAY:RENDER):   1.0   IRAY   rend info : Received update to 00008 iterations after 241.837s.

2018-07-14 19:26:30.888 Iray INFO - module:category(IRAY:RENDER):   1.0   IRAY   rend info : Received update to 00016 iterations after 261.220s.

It should not mention the CPU at all, like it is with smaller scenes. Yes, I do have the latest Nvidia driver and the latests daz3d.
Why is this happening?

Richard Haseltine

Try turning off OptiX, at the bottom of the pane. If the GPUs fail then Iray will fall back to the CPU, it just won't use it (if it isn't checked) while at least one GPU is able to contribute.

TomCatOliver

If it's only happening with large scenes, it sounds like you're running out of vram. Use GPUZ to see how much vram the scene is taking up.