AMIETE – CS (OLD SCHEME)

 

Flowchart: Alternate Process: JUNE 2010Code: AC13                                                                          Subject: OPERATING SYSTEMS

Time: 3 Hours                                                                                                     Max. Marks: 100

 

NOTE: There are 9 Questions in all.

·       Question 1 is compulsory and carries 20 marks. Answer to Q.1 must be written in the space provided for it in the answer book supplied and nowhere else.

·       Out of the remaining EIGHT Questions answer any FIVE Questions. Each question carries 16 marks.

·       Any required data not explicitly given, may be suitably assumed and stated.

 

Q.1       Choose the correct or the best alternative in the following:                                (210)

 

a.    In a time sharing system, when the time slot given to a process is completed, the process goes from running state to

 

      (A) Blocked                                        (B) ready

      (C) suspended                                     (D) terminated

 

b.   In real time operating systems, which of the most suitable scheduling scheme?

 

      (A) Round robin                                 (B) FCFS

      (C) Random scheduling                      (D) Preemptive

 

c.    A system has 3 processes sharing 4 resources. If each process need a maximum of 2 units, then

 

      (A) deadlock can never occur             (B) deadlock may occur

      (C) deadlock has to occur                   (D) none of these.

     

d.   Dirty bit is used to show the

 

      (A) Page with corrupted

      (B) the wrong page in the memory

      (C) page that is modified after being loaded into cache memory

      (D) page that is less frequently accessed

 

e.    Solution of external fragmentation is

 

      (A) compaction                                   (B) paging

      (C) segmentation                                (D) both (A) and (B)

 

f.    a process is said to be in_____ state if it is waiting for an event that will never occur.

 

      (A) Safe                                              (B) unsafe

      (C) starvation                                      (D) deadlock

  

g.   a computer cannot “boot” if it does not have

      (A) operating system                           (B) compiler

      (C) assembler                                      (D) loader                                                                        

                                                                 

h.    The main advantage of interrupt concept is elimination of

 

      (A) spooling                                        (B) polling

      (C) job scheduling                              (D) blocking the currently running process

 

i.    A process is

 

      (A) A programme in suspension         (B) A programme in execution

      (C) A programme in waiting state      (D) A programme in ready state

 

j.    The first fit, best fit and the worst fit algorithm can be used for

 

      (A) contiguous allocation of memory                                                                            

      (B) linked allocation of memory

      (C) indexed allocation of memory     

      (D) all of above

 

 

Answer any FIVE Questions out of EIGHT Questions.

Each question carries 16 marks.

 

 

  Q.2     a.   What are the services provided by the operating system?                                       (8)

                  

             b.   State the dining philosophers problem. Explain the deadlock and starvation in it. Give a pseudo code for its solution which is free from deadlock.                                                           (8)

 

  Q.3     a.  What are the difference between user level threads and kernel supported threads under what circumstances is one type better than the other?                                                      (8)

 

             b.   Consider the following set of processes, with the length of the CPU –burst time given in milliseconds:                                                                                                                                 (8)

                   Process                          Burst time   

                   P1                                   24               

                   P2                                   3

                   P3                                   3   

(i)  Draw a Gantt chart and compute average waiting time illustrating the execution of these processes using FCFS, SJF (Non-preemptive).

(ii) Repeat with round robin scheduling Assuming that the CPU time-slice is 4 milliseconds.

 

Q.4       a.   Differentiate between                                                                                              (8)

                   (i)  CPU bound job and I/ O bound job                                                                            

                   (ii) Preemptive and non-preemptive scheduling

 

             b. What are the four necessary conditions of deadlock? Explain the deadlock avoidance in detail.                                                                       (8)

 

   Q.5          Consider the following page reference string                                                        (16)

                   4,3,2,1,4,3,5,4,3,2,1,5

                   How many page fault would occur for the following page replacement algorithms for 3 page frame? All frames all initially empty.

(i)  FIFO replacement

(ii) LRU replacement

 

  Q.6      a.   A computer has 1000K of main memory. The jobs arrives and finish in the following sequence

                   Job 1 requiring 200K arrives

                   Job 2 requiring 350K arrives

                   Job 3 requiring 300K arrives

                   Job 1 finishes

                   Job 4 requiring 120K arrives

                   Job 5 requiring 150K arrives

                   Job 6 requiring 80K arrives

                   Draw the memory allocation table using best fit and first algorithm and find out which algorithm perform better for the sequence.        (8)                                                                     

                  

             b.   Explain the steps of life cycle of I/O request.                                                         (8)

 

  Q.7     a.  The head of a moving head disk with 100 tracks numbered 0 to 99 is currently serving a request 55. If queue of request is 10, 70, 75, 23, 65 which of the two disk scheduling algorithms FCFS and SSTF (Shorted seek time first) will require less head movement? Find the total head movement for each of the algorithm?                                    (8)                                                                     

      

             b.   Explain deadlock detection in centralized and fully distributed approach. Why is deadlock detection is much more expensive in a distributed environment than it is in a centralized environment?                                                             (8)

 

   Q.8    a.   Explain the following terms:                                                                                    (8)                   

                   (i)   Threads                                       

                   (ii)  File Allocation Methods

                  

             b   Explain the components of Linux system.                                                               (8)                                                                                                                                                              

  Q.9           Write short note on following:                                                                            (44)

            

                  (i)    Distributed System                     

                  (ii)   Parallel Systems                          

                  (iii)  Time Sharing System

                  (iv)  Demand Paging