In polling I/O, the main inefficiency comes from
A) the hardware controller when it notifies the CPU that the device is ready for service.
B) the basic polling operation that may be comprised of several CPU instructions.
C) polling when it is attempted repeatedly yet rarely finds a device ready for service.
D) the slow data transfer rate between a device and the host.

Question

Quizplus · Accepted Answer

Polling I/O becomes inefficient when it is attempted repeatedly but rarely finds a device ready for service. This results in the CPU wasting precious resources and time constantly checking for device readiness. The other options (A, B, and D) may contribute to the inefficiency, but none of them are the main cause of inefficiency in polling I/O.

In Polling I/O, the Main Inefficiency Comes from