Components of Interrupt Response Time

Hardware latency	The time required to make a CPU respond to an interrupt signal.
Software latency	The time to set aside other work and enter the device driver code.
Device service time	The time the device driver spends processing the interrupt, which must be minimal.
Dispatch cycle time	The time to choose the next user process to run, and to return to its code.

The parts are diagrammed in Figure 6-1 and discussed in the following topics.

Figure 6-1 : Components of Interrupt Response Time