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I've got a shader that works fine on my integrated GPU but segfaults on NVIDIA. I use The shader itself is here https://github.com/tombh/total-viewsheds/blob/main/crates/kernels/vulkan-and-cpu/src/kernel.rs I feel like it could be the use of |
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Replies: 5 comments 14 replies
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Are you sure it is being transpiled though? Because I don't think it is unless you're running it in the browser. My understanding is that wgpu will read whatever input you give it and produce whatever output the platform supports, but it will not convert things to and then back from WGSL for no reason. If you give it SPIR-V (which rust-gpu does), then run it on Vulkan-capable GPU, then your SPIR-V will be given to the GPU as is (or close to it). |
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Ohh, so So yes I need some unique features, like But still, we're left with the curiosity that my |
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I just ended up rewriting my algorithms to pack everything into |
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It's just that I know from a CUDA implementation that the That's a good tip about llvmpipe. I actually use it to run CI tests, so I'll look into it. |
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BTW you can open an issue about 16-bit types if there isn't one already. Both Apple Silicon Metal and Vulkan dGPUs support them, my understanding is that only Naga doesn't understand it just yet. I could see myself using it as well in some cases, but it wasn't critical for me yet. |
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So funny thing, I went to see if there was already an issue about this over at the |
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I have a bit of an update, I didn't actually have the Vulkan Validation Layers installed. They're a separate package on Linux. And now I'm seeing a validation error: |
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What is the target you are building with? |
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Just the default, which I think is |
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You can ignore the missing VulkanMemoryModel capability error, that is one of the very few you are allowed to ignore. It formalizes the memory operations and atomics on Vulkan and doesn't leave them as an undefined mess as they were originally, but doesn't actually add any functionality. It's just a guarantee from the driver that it respects that memory model. |
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BTW I was getting crazy memory usage (crashed system once) and strange segfaults after installing Vulkan validation layer package on Ubuntu 24.04. Removed it and everything is fine again. Looks like that thing is buggy. |
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I found the problem. Here's the idea... if you have code like this: #[spirv(compute(threads(8, 8, 4)))]
pub fn main(
#[spirv(global_invocation_id)] id: glam::UVec3,
#[spirv(uniform, descriptor_set = 0, binding = 0)] constants: &constants::Constants,
#[spirv(storage_buffer, descriptor_set = 0, binding = 1)] elevations: &[f32],
#[spirv(storage_buffer, descriptor_set = 0, binding = 2)] cumulative_surfaces: &mut [f32]
) {
if constants.is_accumlate_surfaces {
cumulative_surfaces[0] = 1.234;
}
}But don't define the |
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This probably depends on API used, I believe wgpu checks this and refuses to run if one of the needed buffers is missing |
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That's a good point, but the weird thing is that it's an Nvidia driver issue because it works fine on Mesa. |
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I guess you're in UB territory or something, in which case behavior between implementations is not guaranteed to be anything specific, even Mesa might change in the future versions. |
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I would have expected vulkan validation layers to complain about this before the driver saw the shader, if the pipelineLayout and shader mismatch... |
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Oh yes you're right. Now I can see that it's actually to do with a struct that mixes both references to buffers and local variables. I moved the buffers off the struct and it's all fine now. |
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I had a struct that kept references to buffers and owned local variables. Moving the buffers off the struct allowed the Nvidia version to run. |
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I had a struct that kept references to buffers and owned local variables. Moving the buffers off the struct allowed the Nvidia version to run.