Function perf_now 

pub fn perf_now(_clock: &RobotClock) -> CuTime

Returns a monotonic instant used for local runtime performance timing.

When sysclock-perf (and std) are enabled this uses a process-local RobotClock::new() instance for timing. The returned value is a monotonically increasing duration since an unspecified origin (typically process or runtime initialization), not a wall-clock time-of-day. When sysclock-perf is disabled it delegates to the provided RobotClock.