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Ask HN: How can ChatGPT serve 700M users when I can't run one GPT-4 locally?

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Re: Ask HN: How can ChatGPT serve 700M users when I can't run one GPT-4 locally?

#91
post #17

Earlier quoted context omitted.

Doesn't google have TPU's that makes inference of their own models much more profitable than say having to rent out NVDIA cards? Doesn't OpenAI depend mostly on its relationship/partnership with Microsoft to get GPUs to inference on? Thanks for the links, interesting book!

Yes. Google is probably gonna win the LLM game tbh. They had a massive head start with TPUs which are very energy efficient compared to Nvidia Cards.

The only one who can stop Google is Google.

They’ll definitely have the best model, but there is a chance they will f*up the product / integration into their products.

Re: Ask HN: How can ChatGPT serve 700M users when I can't run one GPT-4 locally?

#92

Earlier quoted context omitted.

Even is the AI bubble does not pops, your prediction about those servers being available on ebay in 10 years will likely be true, because some datacenters will simply upgrade their hardware and resell their old ones to third parties.

Would anybody buy the hardware though? Sure, datacenters will get rid of the hardware - but only because it's no longer commercially profitable run them, presumably because compute demands have eclipsed their abilities. It's kind of like buying a used GeForce 980Ti in 2025. Would anyone buy them and run them besides out of nostalgia or curiosity? Just the power draw makes them uneconomical to run. Much more likely ev…

Off topic, but I bought my (still in active use) 980ti literally 9 years ago for that price. I know, I know, inflation and stuff, but I really expected more than 50% bang for my buck after 9 whole years…

Re: Ask HN: How can ChatGPT serve 700M users when I can't run one GPT-4 locally?

#94
Lots of good answers that mention the big things (money, scale, and expertise). But one thing I haven’t seen mentioned yet is that the transformer math is probably against your use case. Batch compute on beefy hardware is currently more efficient than computing small sequences for a single user at a time, since these models tend to be memory bound and not compute bound. They have the users that makes the beefy hardware make sense, enough people are querying around the same time to make some batching possible.

Re: Ask HN: How can ChatGPT serve 700M users when I can't run one GPT-4 locally?

#95

I work at Google on these systems everyday (caveat this is my own words not my employers)). So I simultaneously can tell you that its smart people really thinking about every facet of the problem, and I can't tell you much more than that. However I can share this written by my colleagues! You'll find great explanations about accelerator architectures and the considerations made to make things fast. https://jax-ml.git…

Same explanation but with less mysticism:

Inference is (mostly) stateless. So unlike training where you need to have memory coherence over something like 100k machines and somehow avoid the certainty of machine failure, you just need to route mostly small amounts of data to a bunch of big machines.

I don't know what the specs of their inference machines are, but where I worked the machines research used were all 8gpu monsters. so long as your model fitted in (combined) vram, you could job was a goodun.

To scale the secret ingredient was industrial amounts of cash. Sure we had DGXs (fun fact, nvidia sent literal gold plated DGX machines) but they wernt dense, and were very expensive.

Most large companies have robust RPC, and orchestration, which means the hard part isn't routing the message, its making the model fit in the boxes you have. (thats not my area of expertise though)

Re: Ask HN: How can ChatGPT serve 700M users when I can't run one GPT-4 locally?

#97

Earlier quoted context omitted.

Yes. Google is probably gonna win the LLM game tbh. They had a massive head start with TPUs which are very energy efficient compared to Nvidia Cards.

Yeah honestly. They could just try selling solutions and SLAs combining their TPU hardware with on-prem SOTA models and practically dominate enterprise. From what I understand, that's GCP's gameplay too for most regulated enterprise clients.

Googles bread and butter is advertising, so they have a huge interest in keeping things in house. Data is more valuable to them than money from hardware sales.

Even then, I think that their primary use case is going to be consumer grade good AI on phones. I dunno why Gemma QAT model fly so low on the radar, but you can basically get full scale Llamma 3 like performance from a single 3090 now, at home.

Re: Ask HN: How can ChatGPT serve 700M users when I can't run one GPT-4 locally?

#98
Baseten serves models as a service, at scale. There’s quite a lot of interesting engineering both for inference and infrastructure perf. This is a pretty good deep dive into the tricks they employ: https://www.baseten.co/resources/guide/the-baseten-inference...

Re: Ask HN: How can ChatGPT serve 700M users when I can't run one GPT-4 locally?

#100

The short answer is "batch size". These days, LLMs are what we call "Mixture of Experts", meaning they only activate a small subset of their weights at a time. This makes them a lot more efficient to run at high batch size. If you try to run GPT4 at home, you'll still need enough VRAM to load the entire model, which means you'll need several H100s (each one costs like $40k). But you will be under-utilizing those card…

I wonder then if its possible to load the unused parts into main memory, while the more used parts into VRAM
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