Operating System-Unix [3i Infotech Placement]: Sample Questions 7 - 9 of 78

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Question 7

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Describe in Detail

Essay▾

What are states that the page can be in, after causing a page fault?

Explanation

Define Page Fault Issues
  • On a swap device and not in memory.
  • On the free page list in the main memory.
  • In an executable file.
  • Marked “demand zero” .
  • Marked “demand fill” .

Question 8

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Describe in Detail

Essay▾

List the system calls used for process management.

Explanation

  • fork ()
    • Create a new process.
  • exec ()
    • Execute a new program in a process
  • wait ()
    • Wait until a created process completes its execution
  • exit ()
    • Exit from a process execution
  • getpid ()
    • Get a process identifier of the current process.
  • getppid ()
    • Get parent process identifier.
  • nice ()
    • Bias the existing priority of a process.
  • brk ()
    • Increase/decrease the data segment size of a process.

Question 9

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Describe in Detail

Essay▾

In what mode the fault handler executes?

Explanation

  • Fault handler executes in kernel mode.
  • Some faults are handled by “fixing” the exceptional condition and returning to the faulting context
  • Fault handler resets faulting context to re-execute instruction that caused the fault.
  • Steps to transfer control to fault handler:
    • UNIX signals fault
    • Fault handler changes the saved context to transfer control to a user- mode handler on return from fault.
    • Handler must be registered with OS. .

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