This is amazing.. ive been working with custom CUDA kernels and https://crates.io/crates/cudarc for a long time, and this honestly looks like it could be a near drop-in replacement.
im especially curious how build times would compare? Most Rust CUDA crates obv rely on calling CMake or nvcc, which can make compilation painfully slow. coincidentally, just last week i was profiling build times and found that tools like sccache can dramatically reduce rebuild times by caching artifacts - but you still end up paying for expensive custom nvcc invocations (e.g. candle by hugging face calls custom nvcc command in their kernel compilation): https://arpadvoros.com/posts/2026/05/05/speeding-up-rust-whi...
> Most Rust CUDA crates obv rely on calling CMake or nvcc, which can make compilation painfully slow.
I anecdotally haven't hit this; see the `cuda_setup` crate I made to handle the build scripts; it is a simple `build.rs` which only recompiles if the file changes, and it's a tiny compile time (compared to the rust CPU-side code)
I am observing the same from the article... is it heavily inspired by Cudarc, i.e. is this intentional, or are we reading too much into this, given Cudarc is a light abstraction over the CUDA api?
perhaps not drop-in, but all my workflows with cudarc have always been "i make cuda kernel, i use cudarc for ffi to said kernels, i call via rust" - which for this case is pretty analogous
briefly looking at the repo, looks like the main workflow is using rustc-codegen-cuda to convert rust -> MIR -> pliron IR -> LLVM IR -> PTX, which is embedded in the host binary, where then cuda-core loads embedded PTX at runtime onto the GPU
but, if you arent directly making cuda kernels and just want cudarc for either calling existing kernels or other cuda driver api access then cudarc is lighter-weight option? or just use one of the sub-crates in this repo like cuda-core for those apis
I'm quite interested in how they dealt with Rust's memory model, which might not neatly map to CUDA's semantics. Curious what the differences are compared to CUDA C++, and if the Rust's type system can actually bring more safety to CUDA (I do think writing GPU kernels is inherently unsafe, it's just too hard to create a safe language because of how the hardware works, and because of the fact that you're hyper-optimizing all the time)
1. use-after-free, drop semantics vs manual cudaFree
2. kernel args enforced using `cuda_launch!` whereas CPP void* args is just an array of pointers, validating count only
3. alias mutable writes. e.g. CPP can have more than one thread writing out[i] with same i and this will compile. but DisjointSlice<T> with ThreadIndex doesnt have any public constructor (see: https://github.com/NVlabs/cuda-oxide/blob/2a03dfd9d5f3ecba52...) and only using API of `index_1d` `index_2d` and `index_2d_runtime`
I think it depends on the objective. My pattern-matching brain says there will be interest in addressing this.
From my perspective of someone who writes applications in Rust and sometimes wants to use GPU compute in these applications: I don't care. If we can leverage the memory model or ownership model in a low-friction way, that's fine. If it makes it a high friction experience, I would prefer not to do it that way.
The baseline is IMO how Cudarc currently does it. I don't think there is much memory management involved; it's just imperative syntax wrapping FFI, and some lines in the build script to invoke nvcc if the kernels change.
This is explained in some detail in the docs. There is a safe layer, a mostly safe layer, and an unsafe layer. Some clunkiness is needed for safe-yet-parallel work that they couldn’t easily fit into the Rust Send/Sync model.
One thing I’ve been wary about with Rust for CUDA is the bit of overhead that Rust adds that is usually negligible but might matter here, like bounds checks on arrays. Could it cause additional registers to get used, lowering the concurrency of a kernel?
Does anyone know if this will let you share structs between host and device? That is the big thing missing so far with existing rust/CUDA workflows. (Plus the serialization/bytes barrier between them)
So, we have stainless, which means Linux code that never rusted. Now we need someone to make phosphorus so that we can turn rusty code into old iron. Then GPL fans can run Rust boxes, Stainless machines, or future proofed iron work horses.
All software can come on three editions. Stainless drivers that were never rusty, oxidized drivers that used Rust on existing code, and Iron editions which is where someone converted the Rust back to C using the new phosphoric tool...
Diversity can be our strength.
Making Iron C/c++ code can be called acid washing if it was rusted.
Hell yea! I have been doing it with Cudarc (Kernels) and FFI (cuFFT). Using manual [de]serialization between byte arrays and rust data structs. I hope this makes it lower friction!
This is a bit good for Rust if you want to use the language with CUDA. The problem is, it still doesn't really move the needle if you really don't like running closed source drivers and runtime binaries and care about open source.
Continuing from this discussion [0], this only makes it a Rust or a CUDA problem rather than a Python, CUDA and a PyTorch one if there bug in one of them.
Yet at the end of the day, it still uses Nvidia's closed source CUDA compiler 'nvcc' which they will never open source. A least Mojo promises to open source their own compiler which compiles to different accelerators with multiple backend support.
> it still doesn't really move the needle if you really don't like running closed source drivers and runtime binaries
Those people probably did not buy an Nvidia GPU for themselves. It should be common knowledge that the "Open" Nvidia drivers still run gigantic firmware blobs to dispatch complex workloads. And Nouveau is close to useless for GPGPU compute.
There is actually work on adding autodiff to Rust, maybe not really first class citizen, but at least build in: https://doc.rust-lang.org/std/autodiff/index.html (it is still at a pre-RFC stage so it is not something that soon will be added)
Incredible, I have never heard of std::autodiff before. Isn't it rare for a programming language to provide AD within the standard library? Even Julia doesn't have it built-in, I wouldn't expect Rust out of all languages to experiment it in std.
Why do we bother with programming languages today? Why not have the LLMs just write assembly code and skip the human readable part? We are not reviewing it anymore anyway.
1) Higher level code is easier for LLMs to review and iterate upon. The more the intent is clear from the code, the easier it is for humans and LLMs to work with.
2) LLMs get stuck or fail to solve a problem sometimes. It is preferable to have artifacts that humans can grok without the massive extra effort of parsing out assembly code.
3) Assembly code varies massively across targets. We want provable, deterministic transformation from the intent (specified in a higher level language) to the target assembly language. LLMs can't reliably output many artifacts for different platforms that behave the same.
4) Hopefully, we are still reviewing the code output by LLMs to some extent.
1.5) Having a compiler in the loop that does things like enforcing type constraints (and in the case if Rust in particular, therefore memory safety guarantees) is really useful both for humans and LLMs.
Feel free to post a project of yours where you gave a bunch of prompts to an LLM and it produced a working application written in assembly without you having to check for anything
I get what you mean but I think if anything AI pairs extremely well with strongly typed languages that are at times cumbersome for humans, but decrease the latency at which AI can get feedback on its code. In my (very) limited experience Rust is an excellent target for AI codegen.
This is a Rust to CUDA converter so I guess it is for codes where the programmer wants it to function properly (Rust) and have good performance (CUDA).
It’s just a matter of different workflows for different users and application.
I mean, AI is not good at writing x86-64 assembly code. Last time I tried (with both Claude and ChatGPT), the AI failed to even create basic programs other than Hello World.
This is amazing.. ive been working with custom CUDA kernels and https://crates.io/crates/cudarc for a long time, and this honestly looks like it could be a near drop-in replacement.
im especially curious how build times would compare? Most Rust CUDA crates obv rely on calling CMake or nvcc, which can make compilation painfully slow. coincidentally, just last week i was profiling build times and found that tools like sccache can dramatically reduce rebuild times by caching artifacts - but you still end up paying for expensive custom nvcc invocations (e.g. candle by hugging face calls custom nvcc command in their kernel compilation): https://arpadvoros.com/posts/2026/05/05/speeding-up-rust-whi...
Cudarc slaps!
> Most Rust CUDA crates obv rely on calling CMake or nvcc, which can make compilation painfully slow.
I anecdotally haven't hit this; see the `cuda_setup` crate I made to handle the build scripts; it is a simple `build.rs` which only recompiles if the file changes, and it's a tiny compile time (compared to the rust CPU-side code)
i'll have to check this out, thanks!
Do other people agree cuda-oxide looks like a near dorp in replacement for cudarc?
That would be amazing, but probably not imo complementarily so.
I am curious what distinguished cuda-oxide. Beyond it being totally under nv control.
I am observing the same from the article... is it heavily inspired by Cudarc, i.e. is this intentional, or are we reading too much into this, given Cudarc is a light abstraction over the CUDA api?
perhaps not drop-in, but all my workflows with cudarc have always been "i make cuda kernel, i use cudarc for ffi to said kernels, i call via rust" - which for this case is pretty analogous
briefly looking at the repo, looks like the main workflow is using rustc-codegen-cuda to convert rust -> MIR -> pliron IR -> LLVM IR -> PTX, which is embedded in the host binary, where then cuda-core loads embedded PTX at runtime onto the GPU
but, if you arent directly making cuda kernels and just want cudarc for either calling existing kernels or other cuda driver api access then cudarc is lighter-weight option? or just use one of the sub-crates in this repo like cuda-core for those apis
I'm quite interested in how they dealt with Rust's memory model, which might not neatly map to CUDA's semantics. Curious what the differences are compared to CUDA C++, and if the Rust's type system can actually bring more safety to CUDA (I do think writing GPU kernels is inherently unsafe, it's just too hard to create a safe language because of how the hardware works, and because of the fact that you're hyper-optimizing all the time)
the main 4 i see are:
1. use-after-free, drop semantics vs manual cudaFree
2. kernel args enforced using `cuda_launch!` whereas CPP void* args is just an array of pointers, validating count only
3. alias mutable writes. e.g. CPP can have more than one thread writing out[i] with same i and this will compile. but DisjointSlice<T> with ThreadIndex doesnt have any public constructor (see: https://github.com/NVlabs/cuda-oxide/blob/2a03dfd9d5f3ecba52...) and only using API of `index_1d` `index_2d` and `index_2d_runtime`
4. im pretty sure you can cuda memcpy a std::string and literally any other POD and "corrupt" its state making it unusable. here it ONLY accepts DisjointSlice<T>, scalars, and closures (https://nvlabs.github.io/cuda-oxide/gpu-programming/memory-a...)
but most of the nitty gritty is in these sections
* https://nvlabs.github.io/cuda-oxide/gpu-safety/the-safety-mo...
* https://nvlabs.github.io/cuda-oxide/gpu-programming/memory-a...
I think it depends on the objective. My pattern-matching brain says there will be interest in addressing this.
From my perspective of someone who writes applications in Rust and sometimes wants to use GPU compute in these applications: I don't care. If we can leverage the memory model or ownership model in a low-friction way, that's fine. If it makes it a high friction experience, I would prefer not to do it that way.
The baseline is IMO how Cudarc currently does it. I don't think there is much memory management involved; it's just imperative syntax wrapping FFI, and some lines in the build script to invoke nvcc if the kernels change.
This is explained in some detail in the docs. There is a safe layer, a mostly safe layer, and an unsafe layer. Some clunkiness is needed for safe-yet-parallel work that they couldn’t easily fit into the Rust Send/Sync model.
One thing I’ve been wary about with Rust for CUDA is the bit of overhead that Rust adds that is usually negligible but might matter here, like bounds checks on arrays. Could it cause additional registers to get used, lowering the concurrency of a kernel?
Does anyone know if this will let you share structs between host and device? That is the big thing missing so far with existing rust/CUDA workflows. (Plus the serialization/bytes barrier between them)
Re: Rust (and "safe" programming languages).
Does anyone have more details on NVIDIAs use of Spark/Ada?
All I can find is what's listed below:
https://www.adacore.com/case-studies/nvidia-adoption-of-spar...
Here's a recording of a 2020 presentation ("Securing the Future of Safety and Security of Embedded Software") from NVIDIA at the AdaCore conference:
https://www.youtube.com/watch?v=2YoPoNx3L5E
So, we have stainless, which means Linux code that never rusted. Now we need someone to make phosphorus so that we can turn rusty code into old iron. Then GPL fans can run Rust boxes, Stainless machines, or future proofed iron work horses.
All software can come on three editions. Stainless drivers that were never rusty, oxidized drivers that used Rust on existing code, and Iron editions which is where someone converted the Rust back to C using the new phosphoric tool...
Diversity can be our strength.
Making Iron C/c++ code can be called acid washing if it was rusted.
Hell yea! I have been doing it with Cudarc (Kernels) and FFI (cuFFT). Using manual [de]serialization between byte arrays and rust data structs. I hope this makes it lower friction!
Here's the repo link https://github.com/NVlabs/cuda-oxide
This is a bit good for Rust if you want to use the language with CUDA. The problem is, it still doesn't really move the needle if you really don't like running closed source drivers and runtime binaries and care about open source.
Continuing from this discussion [0], this only makes it a Rust or a CUDA problem rather than a Python, CUDA and a PyTorch one if there bug in one of them.
Yet at the end of the day, it still uses Nvidia's closed source CUDA compiler 'nvcc' which they will never open source. A least Mojo promises to open source their own compiler which compiles to different accelerators with multiple backend support.
Unlike this...but uses Rust.
[0] https://news.ycombinator.com/item?id=48067228
IMO this has nothing to do with open source as an ideology; just a practical (and official?) lib for adding GPU interaction to your rust programs.
Mojo remains to be seen if it isn't another Swift for Tensorflow, apparently 1.0 won't even support Windows properly.
who the fuck uses windows
The majority of computer owners on planet Earth
But also the majority of programmers?
In AI-focused fields like business analytics and data science, yeah.
many people
> it still doesn't really move the needle if you really don't like running closed source drivers and runtime binaries
Those people probably did not buy an Nvidia GPU for themselves. It should be common knowledge that the "Open" Nvidia drivers still run gigantic firmware blobs to dispatch complex workloads. And Nouveau is close to useless for GPGPU compute.
Personally I really don't want new GPU languages that do not have AD as a first class citizen. I mean rust is an improvement over C++ CUDA but still.
There is actually work on adding autodiff to Rust, maybe not really first class citizen, but at least build in: https://doc.rust-lang.org/std/autodiff/index.html (it is still at a pre-RFC stage so it is not something that soon will be added)
Incredible, I have never heard of std::autodiff before. Isn't it rare for a programming language to provide AD within the standard library? Even Julia doesn't have it built-in, I wouldn't expect Rust out of all languages to experiment it in std.
Sorry, what is AD in this context?
edit: oh, automatic differentiation?
Active Directory
This isn't a new GPU language; it's a lib which might replace FFI and third party libs.
This is definitely not just a lib. This compiles rust to CUDA. If you call a full on compiler stack a lib, everything may as well be a lib.
Really hard to find alternatives to Julia for AD as a first class citizen
I think the parent is mostly referring to solutions like Slang.D
every GPU related post has a comment which makes my eyes roll all the way back. this is the one for this post.
Why do we bother with programming languages today? Why not have the LLMs just write assembly code and skip the human readable part? We are not reviewing it anymore anyway.
A lot of really good reasons:
1) Higher level code is easier for LLMs to review and iterate upon. The more the intent is clear from the code, the easier it is for humans and LLMs to work with.
2) LLMs get stuck or fail to solve a problem sometimes. It is preferable to have artifacts that humans can grok without the massive extra effort of parsing out assembly code.
3) Assembly code varies massively across targets. We want provable, deterministic transformation from the intent (specified in a higher level language) to the target assembly language. LLMs can't reliably output many artifacts for different platforms that behave the same.
4) Hopefully, we are still reviewing the code output by LLMs to some extent.
I'd add to that
1.5) Having a compiler in the loop that does things like enforcing type constraints (and in the case if Rust in particular, therefore memory safety guarantees) is really useful both for humans and LLMs.
Feel free to post a project of yours where you gave a bunch of prompts to an LLM and it produced a working application written in assembly without you having to check for anything
Is this a serious question or are you just trolling?
I get what you mean but I think if anything AI pairs extremely well with strongly typed languages that are at times cumbersome for humans, but decrease the latency at which AI can get feedback on its code. In my (very) limited experience Rust is an excellent target for AI codegen.
This is a Rust to CUDA converter so I guess it is for codes where the programmer wants it to function properly (Rust) and have good performance (CUDA).
It’s just a matter of different workflows for different users and application.
I mean, AI is not good at writing x86-64 assembly code. Last time I tried (with both Claude and ChatGPT), the AI failed to even create basic programs other than Hello World.
Because when this idiotic hypemachinery finally dies an agonising, painful death, some of us still want to work with computers