> This module is under active development. Once upstream, it should allow Rust developers to run Rust code on GPUs. We aim to develop a rusty GPU programming interface, which is safe, convenient and sufficiently fast by default. This includes automatic data movement to and from the GPU, in a efficient way. We will (later) also offer more advanced, possibly unsafe, interfaces which allow a higher degree of control.<p>I really appreciate the work and the effort that went into this. However, such an approach has previously not really worked for C++ with LLVM offload. Why would it work for Rust?
> However, such an approach has previously not really worked for C++ with LLVM offload. Why would it work for Rust?<p>They're very different languages, with different semantics. Without reading more than the synopsis of the paper, they're 100% leveraging the substructural type system and will have a really tight requirement for you to use a certain kind of Rust code at the CPU/GPU boundary.
Unfortunately, the Rust description itself is inconsistent. It claims to be "sufficiently fast by default", yet "sufficiently fast" depends entirely on the requirements of a specific user project. And then it also plans to provide options that do not guarantee memory safety when the default speed is insufficient. It is already common for Rust projects to sprinkle memory unsafe code around when performance is needed.
> It claims to be "sufficiently fast by default", yet "sufficiently fast" depends entirely on the requirements of a specific user project.<p>I think that's why the "by default" is there; the goal is to offer a safe/convenient API that performs well enough that <i>by default</i> you don't need to reach beyond said safe/convenient API. And if you happen to be in a situation where the <i>default</i> performance of the safe/convenient APIs is insufficient, more advanced APIs will be provided.<p>It's a mirror of Rust's general design goals, if anything.
> However, such an approach has previously not really worked for C++ with LLVM offload. Why would it work for Rust?<p>I think that will depend on the exact reason(s) C++ with LLVM offload didn't work out? If Rust differs from C++ in a way that addresses pain points/failure modes/etc. from the C++ attempt, for instance, then perhaps it isn't unreasonable to think Rust could succeed where C++ didn't (c.f., Mozilla's pre-Rust attempts to parallelize Firefox's CSS styling engine). Inversely, if Rust doesn't do things differently in the right way perhaps one might expect the effort to also not work out. Or maybe the problems are entirely non-technical and things could work out in either language.
Seems to work out well for Mojo, so I'd guess it's more an issue with C++.
> However, such an approach has previously not really worked for C++ with LLVM offload<p>... isn't Metal shading language just C++17 compiled with LLVM ? working on every Mac and iPhone in the world is not what I would call "not really worked". Likewise, SYCL works just fine.
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Ownership tracking should map well to GPU memory lifetimes. That's one place Rust has a real edge over C++.
I write all my code in Rust because I am a Rustacean. In many of my custom LLM inference engine projects, the biggest fight has always been bindings. I don’t want to maintain and write bindings; also, if I use an existing project that provides bindings, then I have to wait for the owner to update or fork it and then maintain it on top. It has been a big headache. Running Rust core on GPU sounds like something I will try from day one. Kudos to the team and will watch it closely.
So... why go through LLVM at all instead of having the MIR target PTX/HIP C directly then?<p>If they really wanted a vendor neutral solution for Rust GPU, that already exists: you write the CPU side code, including buffering, allocation, concurrency, etc through Vulkan binding and consume the compute kernel in SPIR-V from HLSL/GLSL/WGSL etc. As it stands, the way they use Rust here feels more like using it like TypeScript types/interfaces than anything else.<p>Again, the size of most operations that should be done on the GPU is known ahead of time before compilation, so it's very much possible to statically allocate memory at compile time instead of going through all this trouble to write what's essentially a Rust shaped DSL for GPU compute.
Because it's convenient? Shader and vulkan semantics can be quite limiting and annoying to write.<p>Maybe it doesn't matter in a post AI world but perhaps it will allow better abstractions.<p>No need to yuck someone else's yum.
People go through trouble to write Python-shaped DSL for GPU compute. We will go "why o why?", but apparently such things are necessary to succeed in the market.
Well, I suppose fake Python is better than fake C++ at least.<p>But yeah, I think Python's dominance in science/ML will eventually pass, just as FORTRAN and Matlab did before.
That's promising but did they publish any code? I can't find anything in the abstract.
is this mainly about making host binaries self-contained for heterogenous workloads?<p>also, seems like this is mostly targeted towards HPC audience?
does anyone know Mojo well enough to comment how Rust + gpu-offload compares to it?
> the rust-gpu project has to emulate pointers[8], which we consider a blocking issue for most
HPC benchmarks.<p>Why is it a blocking issue?<p>I feel like this is very aligned with the goals of rust-gpu.
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The NVIDIA+AMD support is the part I find really interesting. I know OpenMP and SYCL can already target multiple GPU vendors, but doing this while keeping Rust's safety model seems pretty compelling. I'm curious how portable the performance is in practice.
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Genuinely curious what these constant changes are. In fact I don’t feel they’re moving fast enough to give us improvements to core.
It was changing quickly in the earliest releases, about 10 years ago. Like one day I pulled our repo and there was new "?" syntax, but that was a feature I'd been wanting anyway.<p>Edit: Oh, async/await was a bigger and more recent one, 2019. I've heard that this wasn't an easy decision for them but was kinda needed.
That's an opinion. One you're very welcome to hold, but it's not universal by any means. Lots of people enjoy rust.
Fascinating how many people still overcomplicate offloading to GPUs.