Interrupt-driven i/o

Definition

Interrupt-driven I/O is a method of handling input/output operations in computer systems where the CPU is alerted or interrupted by an I/O device when it is ready for data transfer. This approach allows the CPU to perform other tasks while waiting for I/O operations to complete, thus improving overall system efficiency and responsiveness. By relying on interrupts, the system can quickly respond to events without wasting processing power on constant polling of devices.

5 Must Know Facts For Your Next Test

1. In interrupt-driven I/O, when an I/O device needs attention, it sends an interrupt signal to the CPU, which temporarily halts its current task.
2. This method reduces CPU idle time since the CPU can continue processing other tasks while waiting for I/O operations to complete.
3. Interrupts can be prioritized, allowing more important tasks to take precedence over less critical ones during data transfers.
4. Using interrupts helps to avoid bottlenecks that can occur with polling, which can waste valuable CPU cycles checking device status.
5. Most modern operating systems implement interrupt-driven I/O as a fundamental feature for managing efficient multitasking and resource allocation.

Review Questions

• How does interrupt-driven I/O enhance system efficiency compared to polling?
  • Interrupt-driven I/O enhances system efficiency by allowing the CPU to perform other tasks instead of continuously checking if an I/O device is ready. With polling, the CPU wastes cycles on checking device status, even when no data transfer is occurring. In contrast, with interrupts, the device signals the CPU only when it's ready, thus freeing up processing resources and improving overall system responsiveness.
• Discuss the role of an I/O controller in managing interrupt-driven I/O operations.
  • The I/O controller plays a critical role in managing interrupt-driven I/O operations by acting as an intermediary between the CPU and peripheral devices. It generates interrupts to signal the CPU when an I/O device is ready for data transfer, ensuring that the CPU can handle these requests efficiently. By managing multiple devices and their respective interrupts, the I/O controller helps prevent conflicts and ensures smooth data flow in a multitasking environment.
• Evaluate how context switching interacts with interrupt-driven I/O and its impact on system performance.
  • Context switching interacts closely with interrupt-driven I/O because when an interrupt occurs, the CPU must save its current state before servicing the interrupt. This process allows the CPU to respond to high-priority tasks without losing progress on its current operation. While context switching adds some overhead due to state management, effective use of interrupt-driven I/O minimizes idle time and enhances responsiveness, ultimately improving overall system performance despite this overhead.

Related terms

Polling:

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

I/O Controller: A hardware component that manages communication between the CPU and peripheral devices, often responsible for generating interrupts.

Context Switching: The process of storing and restoring the state or context of a CPU so that multiple processes can share a single CPU resource.