Why is tick-free mode needed?

Question

*nix-like systems

A number of UNIX systems operate in tick-free mode, so they do not have periodic timer interrupts. Why is this being done? And does it make sense to use tick-free mode on a computer (eg, an embedded system) running only one process?

Answer 1

they do not have periodic timer interrupts. Why is this being done?

To
- do not wake up the kernel unnecessarily when there are no active tasks;
- do not waste resources in vain, at a time when the only task is active and scheduling is not required;
- do not waste resources on periodic interruptions when several tasks are active, but interrupt execution exactly at the moment when the current process time quantum expires.
It has. Depending on the performance, you will save some computing time and some battery life.

Answer 2

A number of UNIX systems operate in tick-free mode, so they do not have periodic timer interrupts.

What is this "line"? Name!
There are no such UNIX systems (because "UNIX" systems are only those conforming to the POSIX standards).
There is only a FIFO scheduling mode ... but even there it does not mean at all that "they do not have periodic interrupts from the timer."