informIT: The Linux Process Scheduler

“The scheduler is the component of the kernel that selects which
process to run next. The scheduler (or process scheduler, as it is
sometimes called) can be viewed as the code that divides the finite
resource of processor time between the runnable processes on a
system. The scheduler is the basis of a multitasking operating
system such as Linux. By deciding what process can run, the
scheduler is responsible for best utilizing the system and giving
the impression that multiple processes are simultaneously
executing.

“The idea behind the scheduler is simple. To best utilize
processor time, assuming there are runnable processes, a process
should always be running. If there are more processes than
processors in a system, some processes will not always be running.
These processes are waiting to run. Deciding what process runs
next, given a set of runnable processes, is a fundamental decision
the scheduler must make…”

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