Preemption (computing)

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In computing, preemption is the act performed by an external scheduler — without assistance or cooperation from the task — of temporarily interrupting an executing task, with the intention of resuming it at a later time.^[1]: 153 This preemptive scheduler usually runs in the most privileged protection ring, meaning that interruption and then resumption are considered highly secure actions. Such changes to the currently executing task of a processor are known as context switching.