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Polling (I/O)

A technique where the CPU repeatedly checks the status of a device to see if it is ready for an I/O operation.

Categoryhardware

Overview

Polling is the alternative to interrupt-driven I/O. Instead of the device signaling the CPU, the CPU 'asks' the device in a loop: 'Are you ready yet?'

Pros and Cons

  • Pros: Simple to implement; no need for complex interrupt hardware or context switching.
  • Cons: Extremely inefficient; wastes CPU cycles that could be used for other tasks (often called 'busy waiting').

Use Case

Polling is sometimes used in very high-speed networking or storage where the overhead of an interrupt is greater than the time spent polling.