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athrowaway3zyesterday at 5:11 PM1 replyview on HN

> Once a model is built, the biggest cost is inference

Something i cant find any reliable data for, but would help for a sense of scale: How much use before its equal to training?

I.e. assuming you have the training data and setup, and we only care for compute - How hours of using eg Kimi K3 / Fable, for it to equal the compute required to train it?


Replies

philipportneryesterday at 5:50 PM

if you assume that training requires about 3x the compute of inference (one forward pass, one backward pass, parameter updates), and we take DeepSeek-V3 since their numbers are public.

they used ~14.8 trillion tokens with about 2.66 million GPU hours. 14.8 * 3 = 44.4 t inference tokens.

obviously, this is back of the envelope math, but at 100t/s you would need like ~14k years. scale this to >100k GPUs and your in the hours to a couple days range.