In the last couple of days I wanted to try out the new definitive DeepSeek v4 releases. I gave it the repository of a semi-abandoned video compression codec and I told it to perform the usual benchmark -> profile -> verify -> research -> improve loop. I specifically chose this codec because the authors include a verifier for the bitstream to make sure you don't break stuff if you want to try your own implementation. I gave the agents access to the compiler's profiler and also Intel's VTune, which has fantastic output. In a couple of hours the LLM generated SSE and AVX implementations of the compression and decompression algorithms that almost doubled performance with a single core. Then I asked it to create a CUDA implementation using NVIDIA's NSIGHT profiler as a guide and it also started doing some good work.

Personally, I believe that LLMs should be treated like an advanced version of Prolog or linear programming: you give the constraints, you have a way of verifying correctness, and you give it a clear goal. If the LLM can verify itself and course-correct you can basically leave it on autopilot

Meta commentary but it felt fresh to read a long wall of text that didn't seem to be AI generated. Thanks.

Training material seems to be especially rich re GPU kernels and SIMD.

I wonder if there is extra effort put into this because they are useful for the researchers working on the models or just a sub-domain that language models are a great fit for and humans have trouble with?

Isn't cholesky - used to substitute householder at a point - faster but less stable in some cases? I'm just recalling from memory since I had done a small project on qr decomposition with householder for an exam this year. I mean, if it is faster than the standard torch operation probably there are good reasons for which it is not the default standard torch operation. Might as well be wrong, I'm not sure

some of these submissions seem to be omitting the actual rules. the #1 on edinh has a line that says "bypass ban check"

This is really cool - I really like the beam search idea,

Damn! If a solo engineer can do this, it makes the most around OAI/Anthropic start to look pretty weak.

People are always going to hate auto-research and "loop engineering". Because it's got 2 properties:

1) it's the only way to get something out of models (or people for that matter) that they don't know yet.

2) it's harder to do with an LLM than without. Not easier.

3) and when you fuck it up, half the time the LLM (or other ML technique) makes a fool out of you and you spent $1000 to find the quickest way to get a robot leg on the ground is just to crash it into the ground.

Every step here has an oracle: wall-clock, the profile, pass or fail from the verifier. I had an agent-built app audited task by task, 10 came back done and 7 worked, and the three misses were the ones needing a credential or a setting on someone else's dashboard. Nothing in the loop could tell the agent it had failed, so it said done and moved on.

Achieving a 232x speedup on a kernel via automated tooling is an incredible engineering feat. Fascinating read on optimization.

Well, GPU kernels are co-designed really hard. A lot of it is, async tile pipelines + spam my MMA primtives.

Obviously it's still hard, but the point is that, by construction (cause like, NVIDIA literally releases primitives like this, and/or people like TK build slightly higher-level primitives over the base hardware primitives), if you learn the complicated language, you can get really good results, and on some level you "know" you're right by construction even before you go to the actual empirical tests (since you're operating over a higher-level "language", and not arbitrary byte accesses).

Honestly a lot of interfaces and frameworks you could argue are like that, so it's not really a point for GPU kernels relative to other things. But maybe a hint as to what I personally think is important in the AI era - finding the right cuts, the right high leverage abstractions, as otherwise AI is going to produce spaghetti nonsense.

Anecdotally, I saw Opus 5 come up with a complicated loop unrolling technique when I asked it to implement a simple biquad in SIMD, missing a simpler solution. Maybe it was a downgraded session, who knows. That SIMD instruction set, the one for the ESP32-P4, is not very popular and all the documentation it has is a couple of blog posts. So I'm pretty sure it has at most seen some code for a predecessor during its training. However, the LLM was able to derive a full listing of the operations and their arguments from gcc to get us started, and that's why I was able to come up with my own implementation. Along the way, it also came up with insights about possible gotchas. Then, when implementing algorithms, it has been able to reason things out and get things working, despite the ISA not being extremely well known.

They are easily verifiable and hill-climbable.

Because pre-LLMs humans partially "autogenerated" kernels through hyperparameter search and in some sense eating the code complexity in return for performance, and thus built tools for the same automatic verifiability that is useful for LLMs.

In some other tasks, we never built the same level of automatic verifiability since the level of automation in creation being much lower meant it's not giving you as much of a marginal benefit. We prefer code readability and simplicity and such in say, web services, because, say, the database IO time is going to dominate. Here getting an LLM to write a cromulent C# web service is more difficult since it's not easy to automatically verify whether code is cromulent or not. So if you put up LLMs to it, you end up with slop (which works).

OTOH, in kernel design, you give it access to every perf counter, every observable possible and have it optimise all of them. And all are verifiable/hill-climbable