...
Adaptive sampling has been implemented in XPU. The workflow and controls are the same as in RIS: PixelVariance, "darkfalloff", "exposurebracket", "adaptall", and per-channel "relativepixelvariance". There are two "adaptivemetric"s: "contrast" and "variance", with the latter being the default. RMAN-20888
Warning When rendering with adaptive sampling enabled using the GPU, there are known stability issues that cause crashes. On machines configured with virtualized Nvidia GPUs using GRID, these crashes can trigger a hypervisor driver crash that requires a hypervisor restart. This does not happen when rendering on the CPU only or with adaptive sampling disabled. These issues have already been addressed for the next dot release. You can work around this issue by turning off adaptive sampling by setting minsamples and maxsamples to the same value, or by setting PixelVariance to 0.0. RMAN-22085 - An issue where using Render region in Solaris in XPU mode could lead to a crash has been addressed. RMAN-20929
- XPU will fall back to CPU only mode if the variant is "xpu" and no capable GPU hardware is detected. RMAN-21526
- Multiple crash issues surrounding switching between RIS and XPU in Solaris have been addressed.
- The amount of memory required to compile PTX shaders has been reduced, lowering GPU VRAM requirements significantly in some cases.
Eliminated "IMAGE_REL_AMD64_ADDR32NB relocation requires an ordered section layout." errors that could lead to crashes. RMAN-21782
...
- macOS/Apple Silicon: The denoiser is not supported on Apple Silicon, even with Rosetta. RMAN-20408
- If your image has NaNs from either RIS or XPU, the denoiser will fail on macOS and Windows.
- The interactive denoiser currently is not supported in XPU.
XPU
...
- The GPU portion of XPU can render artifacts with trace:reflectexcludesubset. RMAN-20393
- Support for homogeneous single scattering in PxrSurface is incomplete. Renders will be noticeably incorrect after the first bounce off the interior of a closed object. RMAN-16374
- Lights inside objects with homogeneous single scattering in PxrSurface will not compute the correct shadows. RMAN-16367
- Due to differences in how XPU computes derivatives for normals, XPU may compute different results from RIS for bump mapped subdivision surfaces in areas of highly concave curvature, combined with a high bump scale. This happens especially when the bump mapping cannot reasonably approximate the displacement. Note that this difference does not occur with displacement. The issue can be ameliorated by reducing the bump scale. RMAN-21977
- Please refer to the XPU section of the documentation for a more detailed current list of limitations.
...