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Ewan Laidlaw avatar image
Ewan Laidlaw asked ·

Displacement not working (GPU)

I get this error almost every time I attach a displacement shader to a material on the gpu causing the render to fail and a fatal gpu error that requires a Maya restart:

// Error: [gpu] an error happened during rendering : Unknown error (Details: Function "_rtContextLaunch2D" caught exception: Encountered a CUDA error: cudaDriver().CuEventSynchronize( m_event ) returned (700): Illegal address, file: <internal>, line: 0) //

GPU: RTX 2070 Super, MtoA 4.0.4.2

The same displacement setup works on the CPU as normal but my CPU is very old and slow so any solution to allow me to continue to use my GPU would be greatly appreciated, cheers.

shadersgpudisplacementmaterialerror
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Thiago Ize avatar image
Thiago Ize answered ·

As Stephen said, displacement happens on the CPU, but autobump still happens on the GPU. If you disable autobump does that fix it? If it does, you probably have a shader attached to the displacement that isn't playing well with GPU -- what shaders are in your displacement?

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Nope, unfortunately it doesn’t.

It’s the Maya displacement shader with anything attached that causes the error using the GPU (CPU rendering is fine). There’s a good chance its a problem with sharing displaced geo from the CPU to the GPU. Although the error is about the CUDA driver (all my nvidia drivers are upto date) so it could be software, but maybe its hardware as this seems to be a problem specific to me so far.

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Stephen Blair avatar image
Stephen Blair answered ·

Displacement happens on the CPU, and the geometry is then passed on to the GPU.

Can you upload a scene that causes this error?

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Its all scenes, whenever the displacement shader is attached to the shader group and I'm using the gpu, any attempt to render again on the gpu after the error leads to a "fatal gpu error" and Maya needs a restart.

However if I switch to cpu at anytime the rendering works. GPU rendering only works when the displacement shader is detached, CPU rendering works with or without displacement.

I should also add that this error occurs using both image files and procedurals such as aiNoise for the displacement map.

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I don't have any problems with displacement.

Can you get an Arnold log? (see the sidebar for a link to the "Instructions for generating full verbosity log files)

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arnoldLog.txt

If all displacement occurs on the CPU and CPU rendering works fine, I suspect that the CUDA error talking about an illegal address means there is a problem with communication between my CPU & system memory and the GPU?

There haven’t been any other rendering issues on the gpu apart from a generic "fatal gpu error, please restart host application" or occasionally get an error that states there is no suitable GPU available for rendering. So it could be hardware related, my nvidia drivers are upto date but the error is talking about the CUDA driver.

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arnoldlog.txt (3.1 KiB)

Even if it's all displacement scenes that fail, a simple scene (the simpler the better) could still be useful in case there's something special in how you're constructing all your scenes.

Finally, we just released a new version of Arnold. Would you mind testing that just in case it happens to contain a fix for this?

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