Introduction to CUDA programming for Python developers
93 comments
·February 20, 2025ferguess_k
danielmarkbruce
Yes. They are largely unrelated. Just go to Nvidia's site and find the docs. Or there are several books (look at amazon).
A "background in AI" is a bit silly in most cases these days. Everyone is basically talking about LLMs or multimodal models which in practice haven't been around long. Sebastian Raschka has a good book about building an LLM from scratch, Simon Prince has a good book on deep learning, Chip Huyen has a good book on "AI engineering". Make a few toys. There you have a "background".
Now if you want to really move the needle... get really strong at all of it, including PTX (nvidia gpu assembly, sort of). Then you can blow people away like the deep seek people did...
jms55
Lets say you already have deep knowledge of GPU architecture and experience optimizing GPU code to saves 0.5ms runtime for a kernel. But you got that experience from writing graphics code for rendering, and have little knowledge of AI stuff beyond surface level stuff of how neural networks work.
How can I leverage that experience into earning the huge amounts of money that AI companies seem to be paying? Most job listings I've looked at require a PhD in specifically AI/math stuff and 15 years of experience (I have a masters in CS, and no where close to 15 years of experience).
suresk
I've only done the CUDA side (and not professionally), so I've always wondered how much those skills transfer either way myself. I imagine some of the specific techniques employed are fairly different, but a lot of it is just your mental model for programming, which can be a bit of a shift if you're not used to it.
I'd think things like optimizing for occupancy/memory throughput, ensuring coalesced memory accesses, tuning block sizes, using fast math alternatives, writing parallel algorithms, working with profiling tools like nsight, and things like that are fairly transferable?
danielmarkbruce
I don't have a great answer except learn as much about AI as possible - the easiest starting point is Simon Prince's book - and it's free online. Maybe start submitting changes to pytorch? Get a name for yourself? I don't know.
Most companies aren't doing a lot of heavy GPU optimization. That's why deepseek was able to come out of nowhere. Most (not all) AI research basically takes the given hardware (and most of the software) stack as a given and is about architecture, loss functions, data mix, activation functions blah blah blah.
Speculation - a good amount of work will go towards optimizations in future (and at the big shops like openAI, a good amount already is).
pavelstoev
Is this hypothetical person someone you know? if yes, please email me to pavel at centml dotz ai
saagarjha
You can get paid that without the GPU experience so yes. Getting up to speed with this is mostly just a function of how able you are to understand what modern ML architectures look like.
ferguess_k
Thank you! This really helps. I'll concentrate on Computer Architecture and lower level optimization then. I'll also pick one of the books just to get some ideas.
SJC_Hacker
The math isn't that difficult. The transformers paper (https://proceedings.neurips.cc/paper_files/paper/2017/file/3...) was remarkably readable for such a high impact paper. Beyond the AI/ML specific terminology (attention) that were thrown out
Neural networks are basically just linear algebra (i.e matrix multiplication) plus an activation function (ReLu, sigmoid, etc.) to generate non-linearities.
Thats first year undergrad in most engineering programs - a fair amount even took it in high school.
OtherShrezzing
I'd like to re-enforce this viewpoint. The math is non-trivial, but if you're a software engineer, you have the skills required to learn _enough_ of it to be useful in the domain. It's a subject which demands an enormous amount of rote learning - exactly the same as software engineering.
t55
hot take: i don't think you even need to understand much linear algebra/calculus to understand what a transformer does. like the math for that could probably be learned within a week of focused effort.
SJC_Hacker
Yeah to be honest its mostly the matrix multiplication, which I got in second year algebra (high school)0.
You don't really need even need to know about determinants, inverting matrices, Gauss-Jordan elimination, eigenvalues, etc. that you'd get in a first year undergrad linear algebra
dragandj
May I plug-in with ClojureCUDA, a high-level library that lets you write CUDA with almost no overhead, but write it in the interactive Clojure REPL.
https://github.com/uncomplicate/clojurecuda
There's also tons of free tutorials at https://dragan.rocks And a few books! (not free) at https://aiprobook.com
Everything from scratch, interactive, line-by-line, and each line is executed in the live REPL.
codelion
Not a stupid question at all! Imo, you can definitely dive deep into CUDA and GPU architecture without needing to be a math whiz. Think of it like this: you can be a great car mechanic without being the engineer who designed the engine.
Start with understanding parallel computing concepts and how GPUs are structured for it. Optimization is key - learn about memory access patterns, thread management, and how to profile your code to find bottlenecks. There are tons of great resources online, and NVIDIA's own documentation is surprisingly good.
As for the data engineering side, tbh, it's tougher to get into MLE without ML knowledge. However, focusing on the data pipeline, feature engineering, and data quality aspects for ML projects might be
ferguess_k
Thanks for the help!
> As for the data engineering side, tbh, it's tougher to get into MLE without ML knowledge. However, focusing on the data pipeline, feature engineering, and data quality aspects for ML projects might be
I have a feeling that companies usually expect MLE to do both ML/AI and Data Engineering, so this might indeed be a dead end. Somehow I'm just not very interested in the MLE part of ML so I'll dormant that thought for the meanwhile.
> Start with understanding parallel computing concepts and how GPUs are structured for it. Optimization is key - learn about memory access patterns, thread management, and how to profile your code to find bottlenecks. There are tons of great resources online, and NVIDIA's own documentation is surprisingly good.
Thanks a lot! I'll take these points in mind when learning. I need to go through more basic CompArch materials first I think. I'm not a good programmer :D
t55
Agreed, not sure how much math is really needed.
musebox35
I suggest having a look at https://m.youtube.com/@GPUMODE
They have excellent resources to get you started with Cuda/Triton on top of torch. It also has a good community around it so you get to listen to some amazing people :)
codelion
It's definitely possible to focus on the CUDA/GPU side without diving deep into the math. Understanding parallel computing principles and memory optimization is key. I've found that focusing on specific use cases, like optimizing inference, can be a good way to learn. On that note, you might find https://github.com/codelion/optillm useful – it optimizes LLM inference and could give you practical experience with GPU utilization. What kind of AI applications are you most interested in optimizing?
JAlexoid
> Math side of AI but still drill deeper into the lower level of CUDA or even GPU architecture
CUDA requires clear understanding of mathematics related to graphics processing and algebra. Using CUDA like you would use traditional CPU would yield abysmal performance.
> MLE or AI Data Engineering without knowing AI/ML
It's impossible to do so, considering that you need to know exactly how the data is used in the models. At the very least you need to understand the basics of the systems that use your data.
Like 90% of the time spent in creating ML based applications is preparing the data to be useful for a particular use case. And if you take Google ML Crash Course, you'll understand why you need to know what and why.
the__alchemist
I will provide general advice that applies here, and elsewhere: Start with a project, and implement it, using CUDA. The key will be identifying a problem that is SIMD in nature. Choose something you would normally use a loop for, but that has many (e.g. tens of thousands or more) iterations, which do not depend on the output of the other iterations.
Some basic areas to focus on:
- Setting up the architecture and config
- Learning how to write the kernels, and what makes sense for a kernel
- Learning how the IO and synchronization between CPU and GPU work.
This will be as learning any new programming skill.ultrasounder
Very nice-write up. The in-line quiz, which i think is AI generated(QnA) is very useful to test understanding. Wish all tutorials incorporated that feature.
t55
thank you!
spps11
Thanks for sharing, enjoyed reading it!
I have a slightly tangential question: Do you have any insights into what exactly DeepSeek did by bypassing CUDA that made their run more efficient?
I always found it surprising that a core library like Cuda, developed over such a long time, still had room for improvement—especially to the extent that a seemingly new team of developers could bridge the gap on their own.
saagarjha
They didn’t. They used PTX, which is what CUDA C++ compiles down to, but which is part of the CUDA toolchain. All major players have needed to do this because the intrinsics for the latest accelerators are not actually exposed in the C++ API, which means using them requires inline PTX at the very minimum.
t55
They basically ditched CUDA and went straight to writing in PTX, which is like GPU assembly, letting them repurposing some cores for communication to squeeze out extra performance. I believe that with better AI models and tools like Cursor, we will move to a world where you can mold code ever more specific to your use case to make it more performant.
suresk
Are you sure they ditched CUDA? I keep hearing this, but it seems odd because that would be a ton of extra work to entirely ditch it vs selectively employing some ptx in CUDA kernels which is fairly straightforward.
Their paper [1] only mentions using PTX in a few areas to optimize data transfer operations so they don't blow up the L2 cache. This makes intuitive sense to me, since the main limitation of the H800 vs H100 is reduced nvlink bandwidth, which would necessitate doing stuff like this that may not be a common thing for others who have access to H100s.
t55
I should have been more precise, sorry. Didn't want to imply they entirely ditched CUDA but basically circumvented it in a few areas like you said.
pjmlp
Targeting directly PTX is perfectly regular CUDA, and used by many toolchains that target the ecosystem.
CUDA is not only C++, as many mistake it for.
spps11
got it, thanks for explaining.
> with better AI models and tools like Cursor, we will move to a world where you can mold code ever more specific to your use case to make it more performant
what do you think the value of having the right abstraction will be in such a world?
t55
I think that for at least for us dumb humans with limited memory, having good abstractions makes things much easier to understand
musicale
What Jensen giveth, Guido taketh away.
t55
lol. i guess this tutorial is about cutting out guido ;)
signa11
this book:
Programming Massively Parallel Processors by Wen-mei W. Hwu , David B. Kirk , Izzat El Hajj
seems to be tailor mode for folks transitioning from cpu -> gpu arch.t55
Yes, it is great for key concepts but a bit outdated. Hence we added an LLM/FA section in the linked post!
ralphc
Are all the CUDA tutorials geared towards AI or are there some, for example, like regular scientific computing? Airflow over wings and things that you used to see for high-performance computing would be fun to try.
LegNeato
Also check out https://github.com/rust-gpu/rust-gpu and https://github.com/rust-gpu/rust-cuda
the__alchemist
Rust-Cuda is broken and has been for years.`cudarc` is the [only?] working one.
LegNeato
I am in the process of rebooting it: https://rust-gpu.github.io/blog/2025/01/27/rust-cuda-reboot/
t55
this looks really cool and i love rust. just a matter of time until everything runs on rust.
t55
Related: https://sakana.ai/ai-cuda-engineer/
https://www.reddit.com/r/MachineLearning/comments/1itqrgl/p_...
saagarjha
Wasn’t this a bunch of kernels that didn’t work?
t55
What do you mean?
pavelstoev
The hallucinated code was reusing memory buffers filled with previous results so not performing the actual computations. When this was fixed the AI generated code was like 0.3x of the baseline.
imtringued
They don't verify the correctness of their kernels. They expect you to pick the working ones from their kernel junkyard yourself.
The very idea is also dumb as hell. They could have done CUDA -> HIP/oneAPI/Metal/Vulkan/SYCL/OpenCL. Then they wouldn't need to beat the performance of anything, just the automatic porting would be worth an acquisition by AMD or Intel.
tsunego
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m_kos
Since this is on PySpur's website, does anyone have experience with these UI tools for AI agents like PySpur and n8n? I am looking for something to help me prototype a few ideas for fun. I would have to self-host it ($), so I would prefer something relatively easy to configure like Open Hands.
t55
Disclaimer: I work on pyspur
I'd recommend pyspur if you seek
1) More AI-native features eg. Evals, RAG, or even UI decisions like seeing outputs directly on the canvas when running on the agent 2) Truly open-source Apache license 3) Python-based (in the sense that you can run and extend it via python)
On the other hand, n8n is 1) more mature for traditional workflows 2) offering overall more integrations (probably every single integration you can think of) 3) TypeScript based and runs on Node.js
m_kos
Thanks for replying. Do you know when your docs will be a bit more comprehensive? Right now, there is very little information and some links don't work, e.g., Next Steps on this page: https://docs.pyspur.dev/quickstart
t55
> Do you know when your docs will be a bit more comprehensive?
Yes, we're actively working on this, and we should have some more pages by next week. If you have any questions, you can always shoot us an email: founders@pyspur.dev or join our Discord.
> some links don't work, e.g., Next Steps on this page
This might be confusing, the cards below "After installation, you can:" are not meant to be links. Thanks for making us aware, we will improve the wording.
spps11
pyspur is apache 2. it is free to self-host.
whatever1
Any idea what changed recently and we can have end to end simulations (with branches) in the gpu (eg isaac sim) vs in the past where simulations were a cpu thing ?
jamiejquinn
Always been possible, but now the time cost of moving data between the GPU and CPU memory is too high to ignore. Branching may be slower on the GPU but it's still faster than moving data to the CPU for a time then back. The maturation of direct GPU-GPU transfers over the network also helped enable GPU-only MPI codes.
rtkal10
Interestingly, the CUDA implementations are more readable than the pytorch ones.
t55
interesting, you mean they are less obscure?
tsunego
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nitrogen99
If you are a Python dev, why not just use Triton?
t55
Triton sits between CUDA and PyTorch and is built to work smoothly within the PyTorch ecosystem. In CUDA, on the other hand, you can directly manipulate warp-level primitives and fine-tune memory prefetching to reduce latency in eg. attention algorithms, a level of control that Triton and PyTorch don't offer AFAIK.
pjmlp
MLIR extensions for Python do though, as far as I could tell from LLVM developer meeting.
6gvONxR4sf7o
MLIR is one of those things everyone seems to use, but nobody seems to want to write solid introductory docs for :(
I've been curious for a few years now to get into MLIR, but I don't know compilers or LLVM, and all the docs I've found seem to assume knowledge of one or the other.
(yes this is a plea for someone to write an 'intro to compilers' using MLIR)
saagarjha
Triton is somewhat limited in what it supports, and it’s not really Python either.
pavelstoev
or use Hidet compiler (open source)
t55
never heard of Hidet before; for when/what would I use it over CUDA/Triton/Pytorch?
pavelstoev
It is written in Python itself and emits efficient CUDA code. This way, you can understand what is going on. The current focus is on inference, but hopefully, training workloads will be supported soon. https://github.com/hidet-org/hidet
Stupid question: Is there any chance that I, as an engineer, can get away from learning the Math side of AI but still drill deeper into the lower level of CUDA or even GPU architecture? If so, how do I start? I guess I should learn about optimization and why we chose to use GPU for certain computations.
Parallel question: I work as a Data Engineer and always wonder if it's possible to get into MLE or AI Data Engineering without knowing AI/ML. I thought I only need to know what the data looks like, but so far I see every job description of an MLE requires background in AI.