Tutorial Week 12

Questions

    Virtual Memory

  1. What effect does increasing the page size have?

  2. Why is demand paging generally more prevalent than pre-paging?

  3. Describe four replacement policies and compare them.

  4. What is thrashing? How can it be detected? What can be done to combat it?

    5. I/O

  5. Describe programmed I/O and interrupt-driven I/O in the case of receiving input (e.g. from a serial port). Which technique normally leads to more efficient use of the CPU? Describe a scenario where the alternative technique is more efficient.
  6. A device driver routine (e.g. read_block() from disk) is invoked by the file system code. The data for the filesystem is requested from the disk, but is not yet available. What do device drivers generally do in this scenario?
  7. Describe how I/O buffering can be formulated as a bounded-buffer producer-consumer problem.

  8. An example operating system runs its interrupt handlers on the kernel stack of the currently running application. What restriction does this place on the interrupt handler code? Why is the restriction required?