SLO attainment

definition · version 0.1 (draft) · 2026-07-21 · gdput Research

SLO attainment is the proportion of requests that satisfy every defined service-level objective.

Formal definition

For a request set R and SLO set S over a measurement interval, SLO attainment is the count of requests satisfying all objectives in S divided by the count of all completed and failed requests.

Formula

attainment = |R_compliant| ÷ |R_total|

Units

Dimensionless ratio, reported as a percentage (e.g. 91.4%) together with S.

Includes / excludes

Failed and timed-out requests count in the denominator and never in the numerator. Warm-up traffic is excluded from both when declared.

Example

Under S = { TTFT p95 ≤ 4500 ms, ITL p95 ≤ 60 ms }, 914 of 1000 requests meet both targets: attainment = 91.4%.

Common misuse

Reporting per-objective attainment as overall attainment (a request must meet all objectives); mixing percentile-based and per-request formulations without stating which.

Limitations

The distinction between "the SLO" (required outcome) and attainment (whether it was achieved) must be kept: the SLO defines the bar; attainment measures against it.

Preferred citation

gdput Research. "SLO attainment." gdput definitions, v0.1, 2026.
https://gdput.com/definitions/slo-attainment