A mechanism is provided for dynamically power capping one or more units. A power capping mechanism sets a counter value corresponding to an initial energy budget assigned to a unit for a given interval. Responsive to the unit receiving an operation to perform during the given interval, the power capping mechanism decrements the counter value by a decrement value. Responsive to the given interval expiring, the power capping mechanism sends the counter value to a power control loop in the data processing system, receives a new energy budget from the power control loop, and resets the counter value to a value corresponding to the new energy budget assigned to the unit for a next interval.