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Equation 14 · Part 4 · The Real Economics of Shipping a Model to a Device

Symbol U

TCdevice=Cdev+U+Q⋅cd,TCcloud=Q⋅ccloud,TC_{\mathrm{device}} = C_{\mathrm{dev}} + U + Q \cdot c_{d}, \qquad TC_{\mathrm{cloud}} = Q \cdot c_{\mathrm{cloud}},
UU

What this part means

the cost of distributing model updates to the installed fleet, expanded in the next section.

Its job in the formula

U is one of the signed contributions combined to compute the quantity on the left.

Where the article explains it

Define U as the cost of distributing model updates to the installed fleet, expanded in the next section.

The passage around this formula

…fixed, per-release engineering and QA cost of producing and validating the device-tier variant matrix described above — the harness time, the pass/fail sign-off per tier, per quantization scheme, per chip target. Define U as the cost of distributing model updates to the installed fleet, expanded in the next section. Define cdc_{d} as the marginal cost of one additional on-device inference and ccloudc_{\mathrm{cloud}} as the marginal cost of one additional cloud-served inference of the same model. Total cost over Q queries…

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Learn the underlying idea

A variable is a named place for a value. Its letter is a local label: x can mean position in one formula and a data point in another.

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Sources cited in the article section

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