← Lab
logprobcost
mixedPython · llama.cppInference & servingJuly 6, 2026
the question
What does requesting token logprobs cost per token, and does asking for more cost more?
what came out
A fixed per-token overhead -- +6% (1.5B), +10% (0.5B) -- that does NOT grow with k (that prediction was falsified): once you pay for any logprobs, asking for more is nearly free. Exact server timing.
method & receipts
- Result: mixed
- Pre-registered — the prediction was written down and committed before the run.
- Reproducible — one script re-runs the whole thing from scratch.
- Independently reviewed — an adversarial review pass, kept in the repo.
- Machine-readable claims — every reported number, in a checkable file.
- Tested — a correctness/benchmark suite ships alongside the code.
→ read the code and re-run it
github.com/v-code01/logprobcost