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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?

#361

One clever ingredient in OpenAI's secret sauce is billions of dollars of losses. About $5 billion dollars lost in 2024. https://www.cnbc.com/2024/09/27/openai-sees-5-billion-loss-t...

Due to batching, inference is profitable, very profitable. Yet undoubtedly they are making what is declared a loss. But is it really a loss? If you buy an asset, is that automatically a loss? or is it an investment? By "running at a loss" one can build a huge dataset, to stay in the running.

How batched can it really be though if every request is personalised to the user with Memory?

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

#362

Earlier quoted context omitted.

> Inference is (mostly) stateless Quite the opposite. Context caching requires state (K/V cache) close to the VRAM. Streaming requires state. Constrained decoding (known as Structured Outputs) also requires state.

> Quite the opposite. Unless something has dramatically changed, the model is stateless. The context cache needs to be injected before the new prompt, but for what I understand (and please do correct me if I'm wrong) the the context cache isn't that big, like in the order of a few tens of kilobytes. Plus the cache saves seconds of GPU time, so having an extra 100ms of latency is nothing compare to a cache miss. so a…

KV cache for dense models is order 50% of parameters. For sparse moe models it can be significantly smaller I believe, but I don’t think it is measured in kb.

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

#363
post #360
post #356

Earlier quoted context omitted.

> It is absolutely impossible that human assistants being given those tasks would use even remotely within the same order of magnitude the power that LLM’s use. A human eats 2000 kilocalories of food per day. Thus, sitting around for an hour to do a task takes 350kJ of food energy. Depending on what people eat, it's 350kJ to 7000kJ of fossil fuel energy in to get that much food energy. In the West, we eat a lot of me…

Reading your two comments in conjunction - I find your take reasonable, so I apologise for jumping the gun and going knee first in my previous comment. It was early where I was, but should be no excuse. I feel like if you're going to go down the route of the energy consumption needed to sustain the entire human organism, you have to do that on the other side as well - as the actual activation cost of human neurons an…

The unit economics is fine. Inference cost has reduced several orders of magnitude over the last couple years. It's pretty cheap.

Open AI reportedly had a loss of $5B last year. That's really small for a service with hundreds of millions of users (most of which are free and not monetized in any way). That means Open AI could easily turn a profit with ads, however they may choose to implement it.

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

#364
post #360
post #356

Earlier quoted context omitted.

> It is absolutely impossible that human assistants being given those tasks would use even remotely within the same order of magnitude the power that LLM’s use. A human eats 2000 kilocalories of food per day. Thus, sitting around for an hour to do a task takes 350kJ of food energy. Depending on what people eat, it's 350kJ to 7000kJ of fossil fuel energy in to get that much food energy. In the West, we eat a lot of me…

Reading your two comments in conjunction - I find your take reasonable, so I apologise for jumping the gun and going knee first in my previous comment. It was early where I was, but should be no excuse. I feel like if you're going to go down the route of the energy consumption needed to sustain the entire human organism, you have to do that on the other side as well - as the actual activation cost of human neurons an…

> There is a wider point that ChatGPT is less autonomous than an assistant, as no matter the tenure with it, you'll not give it the level of autonomy that a human assistant would have as it would self correct to a level where you'd be comfortable with that.

IDK. I didn't give human entry level employees that much autonomy. ChatGPT runs off and does things for a minute or two consuming thousands and thousands of tokens, which is a lot like letting someone junior spin for several hours.

Indeed, the cost is so low -- better to let it "see its vision through" than to interrupt it. A lot of the reason why I'd manage junior employees closely are to A) contain costs, and B) prevent discouragement. Neither of those apply here.

(And, you know -- getting the thing back while I remember exactly what I asked and still have some context to rapidly interpret the result-- this is qualitatively different from getting back work from a junior employee hours later).

> that maybe for some classes of tasks it just won't be economically viable;

Running an LLM is expensive. But it's expensive in the sense "serving a human costs about the same as a long distance phone call in the 90's." And the vast majority of businesses did not worry about what they were expending on long distance too much.

And the cost can be expected to decrease, even though the price will go up from "free." I don't expect it will go up too high; some players will have advantages from scale and special sauce to make things more efficient, but it's looking like the barriers to entry are not that substantial.

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

#366
post #239

Earlier quoted context omitted.

> But this seems like the easiest one to implement. Even easier: Just fail. In my experience the ChatGPT web page fails to display (request? generate?) a response between 5% and 10% of the time, depending on time of day. Too busy? Just ignore your customers. They’ll probably come back and try again, and if not, well, you’re billing them monthly regardless.

Is this a common experience for others? In several years of reasonable ChatGPT use I have only experienced that kind of failure a couple of times.

> Is this a common experience for others?

I should think about whether my experience generalizes.

The user seems to have had a different experience.

Stopped reasoning.

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

#367

Earlier quoted context omitted.

But that’s not accurate. There are all sorts of tricks around KV cache where different users will have the same first X bytes because they share system prompts, caching entire inputs / outputs when the context and user data is identical, and more. Not sure if you were just joking or really believe that, but for other peoples’ sake, it’s wildly wrong.

Really? So the system recognises someone asked the same question and serves the same answer? And who on earth shares the exact same context? I mean i get the idea but sounds so incredibly rare it would mean absolutely nothing optimisation wise.

Yes. It is not incredibly rare, it's incredibly common. A huge percentage of queries to retail LLMs are things like "hello" and "what can you do", with static system prompts that make the total context identical.

It's worth maybe a 3% reduction in GPU usage. So call it a half billion dollars a year or so, for a medium to large service.

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

#368

Earlier quoted context omitted.

I think I finally found an actual product page: https://bdachelp.zendesk.com/hc/en-us/articles/2319602600002... The amazon page specifically said 1354 watts, but I think that's actually for the 14300BTU model. 12000BTU is 9.72 amps. Anyway, doesn't this make my actual argument stronger? These units fit even better into a normal circuit than I thought, and make the mini-split look even worse in comparison.

4.5-5A at 240V = 9.72A at 120V It’s the same level of power consumption. I’m not even sure what you’re asking at this point, to be honest.

You were talking about needing a second 240V 20A circuit, and you later backed that up by citing the spec sheet of 230V mini-split with a minimum circuit rating of 15A.

My argument was that you do not need such a circuit.

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

#369

Earlier quoted context omitted.

4.5-5A at 240V = 9.72A at 120V It’s the same level of power consumption. I’m not even sure what you’re asking at this point, to be honest.

You were talking about needing a second 240V 20A circuit, and you later backed that up by citing the spec sheet of 230V mini-split with a minimum circuit rating of 15A. My argument was that you do not need such a circuit.

Technically you’re correct, a 12000 BTU minisplit only uses around 1000 watts while running which is just over 4A.

The breaker size being 20A 2P is a consequence of the NEC requiring you to size the wire based off the equipment nameplate rating of 15A, which is based off the full load amps of the motors inside the equipment.

Full load amps is the max amount of current a motor can draw at a specific voltage and is used for sizing wire and overcurrent protection for a piece of equipment. It doesn’t always match up the current a motor draws while it’s running normally. You take full load amps times 1.25 to get minimum circuit ampacity, which you use to size the conductors.

So while you are correct that a 240V 12000 BTU minisplit wont draw anywhere near 20A, the specific minisplit I looked at required a 20A breaker due to the minimum circuit ampacity being 15A. If the MCA was 12A, you could use a 15A breaker; an MCA of 8A would allow using a 10A breaker, and so on.

If you use fuses, you can size the overcurrent protection at 100%, breakers require 125% of the load for a continuous load. So you could use a 30A fusible disconnect switch fused at 15A for a unit with an MCA of 15A.

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

#370

Earlier quoted context omitted.

You were talking about needing a second 240V 20A circuit, and you later backed that up by citing the spec sheet of 230V mini-split with a minimum circuit rating of 15A. My argument was that you do not need such a circuit.

Technically you’re correct, a 12000 BTU minisplit only uses around 1000 watts while running which is just over 4A. The breaker size being 20A 2P is a consequence of the NEC requiring you to size the wire based off the equipment nameplate rating of 15A, which is based off the full load amps of the motors inside the equipment. Full load amps is the max amount of current a motor can draw at a specific voltage and is use…

That's not the angle I'm taking. I'm not saying anything about what the mini-split actually uses. Give it the circuit that the nameplate asks for.

Instead I'm saying that particular minisplit is a lazy design and we can get a 12000 or higher BTU unit with a much smaller nameplate rating. Not only will it only need a single-pole breaker, the required circuit probably already exists.

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