Pre-emptive multitasking

Pre-emptive multitasking is a form of multitasking. To understand the concept, compare to cooperative multiprocessing, in which only the active task (a.k.a. process) may initiate a context switch:

• Because the task has completed processing.
• Because the task has become blocked on a shared resource.
• Because the task is yielding the processor to another, similarly cooperative, task.

In pre-emptive multitasking, the Operating System kernel can also initiate a context switch to satisfy the scheduling policy's priority constraint, thus pre-empting the active task.

Usage: Pre-emptive multitasking is sometimes mistakenly used when the intended meaning is more specific, referring instead to the class of scheduling policies known as time-shared scheduling, or time-sharing.

See also

• Scheduling
• Scheduling policy
• Time-sharing