Question

Consider a system running under two types of workloads: (a) CPU-intensive jobs, (b) I/O-intensive jobs. Which of the following statements about the relative performance of Interrupt-driven I/O and Programmed I/O is correct?

• A. Programmed I/O performs better for CPU-intensive jobs, while interrupt-driven I/O performs better for I/O-intensive jobs
• B. Interrupt-driven I/O performs better in both CPU-intensive and I/O-intensive workloads because it always reduces CPU involvement
• C. Interrupt-driven I/O performs better for CPU-intensive jobs by freeing the CPU, while programmed I/O performs better for I/O-intensive jobs due to tighter control
• D. Programmed I/O performs better in both CPU-intensive and I/O-intensive workloads because it gives the CPU full control

Hint:

Interrupt-driven I/O improves CPU utilization for CPU-intensive tasks, while programmed I/O provides more control for I/O operations.

Answer 1

The Correct Option is C

- Programmed I/O requires the CPU to wait for I/O operations to complete before continuing with other tasks. This can be inefficient for CPU-intensive jobs because the CPU is blocked during I/O operations.
- Interrupt-driven I/O allows the CPU to perform other tasks while waiting for I/O operations to complete, which is more efficient for CPU-intensive jobs as it frees up the CPU to do other processing.
- For I/O-intensive jobs, programmed I/O can be more effective as it provides tighter control over when and how I/O operations occur.
Thus, the correct answer is (c), as interrupt-driven I/O is ideal for CPU-intensive jobs because it allows the CPU to be freed, and programmed I/O works better for I/O-intensive jobs due to its more direct control.