Show HN: Luminal – Open-source, search-based GPU compiler

Cool project! How do you think about targeting hardware-specific ISAs directly? There’s an interesting paper from Citadel (https://arxiv.org/pdf/1804.06826) that highlights inefficiencies in nvcc for the Volta architecture. Do you see Luminal’s search-based paradigm eventually extending beyond outperforming handwritten kernels, towards actually competing with NVIDIA’s compiler optimizations at the PTX level?

So wait, am I understanding this correctly?

Instead of applying just predetermined optimization rules or patterns, the compiler formulates the problem as searching through many possible configurations or versions of the code. Each possible version can have different arrangements, tiling sizes, thread block configurations, memory access patterns, and instruction sequences, right?

And from my understanding, the “search space” is just a collection of all potential versions of the code (kernels) that the compiler can generate from the original input. So for example, the space might include

- Different ways to partition workloads among GPU threads and blocks

- Varying memory access strategies (using shared memory, global memory)

- Various instruction-level optimizations or reordering

- Alternative loop unroll factors or vectorization strategies

The compiler then programmatically produces a large number of candidate kernels by combining different optimizations and configurations. Among these millions of candidates, the compiler tries to find the one that performs best.

In that case, can the compiler print out which gpu configuration works the best for that computer? And will that configuration be applicable to all computers with the same setup?

This is such an interesting technique.

> Luminal can run Q8 Llama 3 8B on M-series Macbooks at 15-25 tokens per second. The goal is to become the fastest ML framework for any model on any device.

Great that some numbers are provided, but in isolation, I'm not sure what they provide. It would be helpful to also share what tok/s you'd get with llama.cpp or something else on the same hardware, so we can actually understand if it's faster or not :) Also including the prompt processing would be a bonus!

Very cool project. Earlier tinygrad used to have ~25 ops but now it has grown to 86 and I believe it is primarily to support hardware feature like tensor core and tma. I don't think luminal supports tensor cores as of now, how do you think the ops will evolve as the library matures.

I see you guys are using Egg/Egglog! I've been mildly interested in egraphs for quite a while, glad to see they're gaining traction!

This is very cool. Do you have any advice on papers to read to understand the details of search based compilation a bit more?

When you say (in the video) that you can target more exotic hardware, what about things FGPA accelerators (maybe taking advantage of TVM's FPGA backend)?

Also, what about CUDA alternatives like ROCm?

Cool! How is this project different from the tuning process in TVM?