When are there no ticks? - briefly
Ticks are absent when the timer or scheduler is disabled, or when the interval parameter is set to zero, preventing any periodic events from being generated. In such cases the system produces no tick signals at all.
When are there no ticks? - in detail
Ticks disappear under conditions where the underlying timing mechanism is either halted, disabled, or yields a zero interval. In a software environment, a tick is generated by a clock source that increments a counter at regular intervals. Absence of ticks occurs when:
- The clock source is turned off, such as during system sleep, standby, or power‑down states.
- The timer configuration sets the period to zero, causing the scheduler to skip tick generation.
- Interrupts that deliver tick signals are masked or globally disabled, preventing the processor from receiving the pulse.
- The operating system runs in a tick‑less mode, where the kernel calculates elapsed time on demand rather than relying on periodic interrupts.
- The hardware timer overflows or fails, leading to a loss of the periodic pulse until recovery routines re‑initialize the device.
In real‑time embedded systems, the same principles apply: disabling the peripheral that drives the system tick, entering a low‑power mode that suspends the timer, or configuring a watchdog to suppress regular ticks all result in a tick‑free interval.
From a mathematical perspective, a discrete‑time sequence contains no ticks when the step size approaches zero, effectively turning the sequence into a continuous function. In such a limit, the notion of individual ticks becomes meaningless.
Therefore, any scenario that eliminates the periodic signal—whether by power management, configuration choices, interrupt control, or mathematical abstraction—produces an interval without ticks.