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Three open-weights models could serve your product. How do you choose?

Benchmark rankings answer a question your product did not ask, and candidates usually differ more in what they cost to serve than in what they can do. The four axes in elimination order, and the deployment floor that rules candidates out before quality is discussed.

Updated Sep 2026 · Grounded in real AI infrastructure interview loops and written to a senior-engineer editorial bar, with every number worked and every diagram hand-built.

Benchmark rankings answer a question your product did not ask, and candidates usually differ more in what they cost to serve than in what they can do. The four axes in elimination order, and the deployment floor that rules candidates out before quality is discussed.

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The concepts behind this question

Ranked by how closely each one overlaps this question's topic, so the first card is the thing to read if the answer above moved too fast.

Foundational
🧮 Open Weights & Serving Engines
Capacity Planning for Open-Weights FleetsPlanning a fleet for a sparse open-weights model works differently from planning one for a dense model, because memory follows total parameters and throughput follows active parameters, and those now differ by more than twenty times. The sizing goes in one direction only: from a traffic forecast to tokens per second, to replicas at a measured operating point, to GPUs, to racks and kilowatts. Doing it in the other direction, from an available GPU count, produces a fleet that fits the hardware rather than the demand.
Foundational
🧮 Open Weights & Serving Engines
Serving Benchmarks That Do Not LieMost published serving numbers are not comparable to each other and not predictive of production, because they differ in the input distribution, the concurrency, whether the cache was warm, and which of several very different metrics is being reported. A benchmark that supports a decision has to fix all four, report a distribution rather than a mean, and be run against the traffic shape you actually serve. The single most useful discipline is to compute the bandwidth bound first, so you know what fraction of the possible you achieved.
Foundational
🧭 Ownership & Judgment
Talking About Cost and Capacity with LeadershipInfrastructure engineers are asked to justify large numbers to people who do not share their vocabulary, and the conversations go wrong in predictable ways: a technical objection with no alternative, a forecast with no assumptions, or a cost quoted in a unit the listener cannot act on. What works is a small number of costed options, a stated recommendation, the decision needed by a date, and every figure expressed in whatever the listener actually controls.
Foundational
📐 AI Systems Design
Multi-Region Serving and FailoverRunning inference in more than one region buys latency for distant users and survival when a region fails, and it costs a second fleet that must be capable of absorbing the first one's traffic. The design turns on three decisions: whether regions are active-active or active-passive, what state has to cross regions and what deliberately does not, and how much headroom each region carries so a failover does not simply move the outage.
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FEDITOR'S NOTE

Scored on evaluating on the product's own tasks, on the deployment floor eliminating candidates early, and on cost per delivered token rather than per parameter.

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