pmgr (power manager)

pmgr — power manager — is the IOKit driver that owns the SoC's power-control registers on Apple Silicon. The single source of truth for "what's powered, at what voltage, running at what frequency."

What pmgr does:

• DVFS — selects per-cluster voltage and frequency from a table of P-states. Higher P-state = more performance + more power.
• Idle gating — when all cores in a cluster are idle, drop voltage, stop the clock, eventually power-gate the cluster entirely.
• Wake coordination — restore cluster state when a core needs to wake.
• Per-island sequencing — bringing up the GPU is a multi-step sequence (power → clock → unreset); pmgr orchestrates.

pmgr publishes a power-state interface that other IOPM-aware drivers consume. They tell pmgr "I need full power" or "I'm idle"; pmgr aggregates across the system and picks the right global state.

You can observe pmgr's decisions via:

powermetrics --samplers cpu_power,gpu_power
pmset -g

See also: IOPM, DVFS, and the Apple Silicon power management article.