Monotonic time is a measurement of the time since the system was powered on and is maintained by the kernel. Note that the monotonic time may not always reset to zero on reboot and the behavior during sleep/suspend has not yet been defined.
Monotonic time is the most reliable time standard on Fuchsia and reading monotonic time is usually cheaper than reading UTC or local time. Monotonic time is always available and it always increases continuously and monotonically. Monotonic time is locked to the frequency of the underlying hardware oscillator and does not attempt to correct for any errors in that oscillator.
Since monotonic time counts from power on, it is only meaningful in the context of a single power cycle on a single Fuchsia device.
Components may read monotonic time using