Why do we need a swapper task in linux?

Question

The idle task (a.k.a. swapper task) is chosen to run when no more runnable tasks in the run queue at the point of task scheduling. But what is the usage for this so special

Answer 1

You can use ps -ef and it will list the no of process which are running. Then in the first link, it will list the first pid - 0 which is the swapper task.