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INTRODUCTION - Skynet

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INTRODUCTION - Skynet Powered By Docstoc
					                     Sample Questions for EE6012
                                       1/March/2011

          This is the revision set of questions for the in-term exam.


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OPERATING SYSTEMS – PROCESSES

Introduction

1) Give a definition for a computer operating system.

2) What does the term POSIX mean is respect to the UNIX/Linux operating
   system and what is its significance?

3) Draw a simple block diagram of a Linux operating system and briefly say what is the
   purpose of each major block in the kernel.

4) Assume a system, at a given instant, has one running process, three ready processes, two
   blocked processes on blocked queue_x and one blocked process on blocked queue_z.
   Draw the queuing structure at this instant, showing in your diagram how the queued
   PCBs are linked using the relevant PCB fields.

5) With the aid of a state diagram show the various states for a process in a multitasking
   system which supports load balancing (i.e. includes the suspended states). Clearly label
   all state transitions.

6) Draw a typical PCB (process control block) for a process in a multitasking environment
   and briefly state the purpose for each field in your PCB.

7) State clearly what is the difference between a process and a thread.



Scheduling

1) Briefly state what is meant by the following types of process activity:
       - Processor-bound activity
       - I/O bound activity

2) Draw a diagram for a round-robin scheduler and state one advantage and
   one disadvantage for this type of scheduler.

3) Describe the operation of a Multi-Level Feedback Scheduler for a single-processor multi-
   tasking system. Use a diagram to show how the queuing structure is arranged. State one
   disadvantage to this scheme.


4) For the Microsoft Windows (Win32) scheduler, answer the following:


EE6012 – Sample questions                             1
    a) Draw a block diagram for the user level environment of the Microsoft Windows
       operating system. About ten blocks are expected.

    b) Draw a block diagram for the kernel level environment of the Microsoft Windows
       operating system. About ten blocks are expected.

    c) What in meant by the Win-32 interface?

    d) With respect to the Microsoft Windows Win-32 scheduler, please answer the
       following:

    -   How many priority levels exist in the scheduler design?
    -   What is a thread?
    -   If a process has a nominal priority level of 13 what is the highest
        thread level priority for that process?
    -   Briefly describe what is meant by starvation prevention in the context
        of the Microsoft Windows scheduler?
    -   State a typical pre-emption time quantum for the Microsoft Windows
        scheduler in: 1) a Server configuration and 2) in a Workstation configuration.



FILE SYSTEMS

1) Briefly describe the elevator algorithm for disk head scheduling within a multi-tasking
   system. State the reasons why this solution is better than a first come first served (FCFS)
   algorithm.

2) A disk drive is specified to have an average seek access time of 6 milliseconds and a spindle
   rotational speed of 10,000 rpm. Calculate the average total latency time required to find a
   random sector on this disk drive. Show your calculations.

3) A disk drive is specified to have a spindle rotational speed of 10,000 rpm. Assume that each
   track contains 1024 sectors, where each sector is 512 bytes in size. Calculate the raw
   read/write data transfer rate in bits/second for a track on this disk drive. Show your
   calculations.

4) In relation to the block size (cluster size) for a file system:
        (i) What is considered to be a typical block size?
        (ii) State a disadvantage for a large block size
        (iii) State a disadvantage for a small block size

5) For the FAT file system:

    a) Draw a simple FAT table diagram to show an example of how clusters are mapped to
       a small 3-cluster file. In the table indicate ‘free clusters’ and a ‘bad cluster’.

    b) If a FAT16 file system uses a cluster size of 16kBytes, what is the maximum
       partition size for this system?

6) For a UNIX style file system:

    a) Draw a typical i-node structure showing each field entry.



EE6012 – Sample questions                               2
    b) Draw a diagram showing how the i–node is used to keep track of a file’s disk blocks.

7) A UNIX style file system is implemented using 1kByte (1024) disk blocks and 32-bit size
   block addresses. The i-node holds 12 direct block addresses, one single-indirect block
   address, one double-indirect block address, and one triple-indirect block address.
   Showing your calculations, what is the maximum file size for such a file system, and
   what is the maximum file system size?

8) A Linux ext3 file system supports directory entries of dynamic length. Draw a directory
   entry data structure to support such a directory entry and briefly explain each field in your
   structure. State what is the typical maximum filename size for such a Linux file system.

9) The Linux ext3 file system uses a concept referred as block groups. What is the primary
   advantage of using such block groups? Draw a diagram to show the structure of a block
   group and name each field. State the purpose of the group descriptor field in the block
   group.

10) For a Linux ext3 file system, if the block size is 4kBytes, then what is the maximum size
    of a single block group? Show your calculation.

11) Draw a block diagram for the architecture of a Linux Virtual File System (VFS).
    Briefly state the purpose of each block in your diagram. Name five types of file systems
    that are supported in the Linux VFS.



RAID and disk spanning

1) Describe what is meant by the term ‘RAID’, and state any advantages for RAID.

2) For a RAID level 4 scheme, briefly describe how a failed drive is reconstructed.

3) Explain clearly why RAID level 5 is better than RAID level 4.

4) Draw a block diagram for a hardware RAID scheme showing a single RAID volume and
   four disk drives.

5) Briefly describe what the term disk spanning means. Draw a diagram for system with
   five logical volumes and five physical disk drives, where the physical disks are grouped
   in a group of 2 physical disks and a group of 3 physical disks.




EE6012 – Sample questions                             3

				
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posted:10/25/2011
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Lingjuan Ma Lingjuan Ma
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