Sample Questions Best site for GRE, LSAT, SAT, GMAT, TOEFL, CCNA, CCSA and interview sample questions  

Technical Sample Questions : C |  C++ |  Oracle |  Java | Unix |  Operating Systems |  Data Structure

Sample Technical Questions

Unix Sample Questions

Questions on memory management in uinx

  1. At what mode the fault handler executes?

    Answer:

    At the Kernel Mode.
  2. What do you mean by the protection fault?

    Answer:

    Protection fault refers to the process accessing the pages, which do not have the access permission. A process also incur the protection fault when it attempts to write a page whose copy on write bit was set during the fork() system call.

  3. How the Kernel handles the copy on write bit of a page, when the bit is set?

    Answer:

    In situations like, where the copy on write bit of a page is set and that page is shared by more than one process, the Kernel allocates new page and copies the content to the new page and the other processes retain their references to the old page. After copying the Kernel updates the page table entry with the new page number. Then Kernel decrements the reference count of the old pfdata table entry.

    In cases like, where the copy on write bit is set and no processes are sharing the page, the Kernel allows the physical page to be reused by the processes. By doing so, it clears the copy on write bit and disassociates the page from its disk copy (if one exists), because other process may share the disk copy. Then it removes the pfdata table entry from the page-queue as the new copy of the virtual page is not on the swap device. It decrements the swap-use count for the page and if count drops to 0, frees the swap space.

  4. For which kind of fault the page is checked first?

    Answer:

    The page is first checked for the validity fault, as soon as it is found that the page is invalid (valid bit is clear), the validity fault handler returns immediately, and the process incur the validity page fault. Kernel handles the validity fault and the process will incur the protection fault if any one is present.
  5. In what way the protection fault handler concludes?

    Answer:

    After finishing the execution of the fault handler, it sets the modify and protection bits and clears the copy on write bit. It recalculates the process-priority and checks for signals.
  6. How the Kernel handles both the page stealer and the fault handler?

    Answer:

    The page stealer and the fault handler thrash because of the shortage of the memory. If the sum of the working sets of all processes is greater that the physical memory then the fault handler will usually sleep because it cannot allocate pages for a process. This results in the reduction of the system throughput because Kernel spends too much time in overhead, rearranging the memory in the frantic pace.

« Previous

Unix Sample Question Number : 1-5 | 6-11 | 12-16 | 17-23 | 24-29 | 30-36 | 37-41 | 42-48 | 49-55 | 56-61 | 62-67 | 68-73
Sample Test Questions
GRE Sample Questions
CAT Sample Questions
GMAT Sample Questions
TOEFL Sample Questions
ACT Sample Questions
SAT Sample Questions
LSAT Sample Questions
PSAT Sample Questions
MCAT Sample Questions
PMP Sample Questions
GED Sample Questions
ECDL Sample Questions
DMV Sample Questions
CCNA Sample Questions
MCSE Sample Questions
Network+ Sample Questions
A+ Sample Questions
Technical Sample Questions
WASL Sample Questions
CISA Sample Questions

Other Sample Questions
Sample Interview Questions
Sample Teacher Interview Questions
Sample Citizenship Questions
Accuplacer Sample Questions
Science Bowl sample Questions
Driving Test Sample Questions
Sample Survey Questions Sample Essay Questions
Sample Behavioral Interview Questions

Copyright © 2004-2013, Best BSQ. All Rights Reserved.