Skip to main content

Energy numbers on cloud VMs: TDP estimation for RAPL-less nodes

avuru obs team
Maintainers

The green module reported energy only where the hardware exposes RAPL — which excludes the overwhelming majority of public-cloud VMs. An opt-in TDP estimator now models CPU power from utilization on those nodes, so a fleet that runs entirely on cloud instances stops seeing an empty /green.

  • Honest by construction. Every number the estimator produces is stamped estimated through the whole chain — the SQL, the API, the UI and the CSRD export's methodology block — and is never blended with RAPL-measured energy. Estimated and measured energy for the same service appear as separate rows, so a total can never quietly mix the two. Treat estimates as trend and regression grade (±30-50% typical error), not audit grade.
  • The RAPL-less share becomes visible. /green gains a coverage panel breaking the fleet into known, measured, estimated and absent nodes. What used to be silently missing is now something you can see and act on.
  • Budgets account for it. Carbon budgets include estimated energy, so an all-VM fleet's budget can actually trip — and a breach states how much of it is modeled versus measured.
  • Sourced coefficients. The bundled CPU power table is cited (Cloud Carbon Footprint, cross-checked against the SPECpower-derived source notebook), and operators can override P_idle/P_max per node or fleet-wide.

Enable it with sensor.green.estimation.enabled (it requires sensor.green.enabled — the estimator is a fallback for the same energy signal, not a second source). See the green module docs.