Power BI Premium evaluates your level of utilization by aggregating utilization records every 30 seconds. Each evaluation is composed of two different aggregations: Interactive utilization and background utilization.
Interactive utilization is evaluated by considering all the interactive operations that completed on or near the current half-minute evaluation cycle.
Background utilization is evaluated by considering all the background operations that completed during the past twenty-four hours, where each background operation contributes only 1/2880 of its total CPU cost (there are 2880 evaluation cycles in each 24-hour period).
A capacity consists of a defined number of v-cores. The Power BI Premium Utilization and Metrics app tracks the utilization of your capacity v-cores. The CPU usage reported in the app drives the need to autoscale.
If you have a P1 subscription with eight v-cores, each evaluation cycle quota is 240 (8 × 30) seconds of CPU utilization. If the sum of both utilizations exceeds the total v-quota in your capacity, your capacity will autoscale using an additional v-core for the next 24 hours.
Autoscale always looks at your current capacity size to evaluate how much resource you use. If you have already autoscaled using one v-core, your maximum capacity is now at 270 (240 + 1 × 30) seconds of CPU time in an evaluation cycle.
Autoscale always makes sure that no single interactive operation can consume all of your capacity, and you must have two or more interactive operations taking place in a single evaluation cycle to initiate autoscale.