llm logging: what separates "readable" from "usable"
Short version: llm needs almost no tuning at small and medium scale — the point where it starts to hurt is much further out than most people assume. Full measurements below.
We also fixed monitoring along the way: replaced average-based alerts with percentiles and split them per endpoint. False alerts dropped by about seventy percent and the on-call rotation visibly cheered up.
What genuinely surprised me was the tail. The average looked great while P99 jumped by an order of magnitude past some threshold. The cause was not llm itself but our upstream connection reuse — the load test traffic was too clean and hid the long-tail requests.