Operating System |Gate-2011| previous year question|Set-10

Set-15 Operating System Questions

Operating System |Gate-2011|

  1. Let the page fault service time to 10 ms in a computer with average memory access time being 20 ns. If one page fault is generated for every 106 memory accesses, what is the effective access time for the memory? [GATE – 2011]

a. 21 ns
b. 30 ns
c. 23 ns
d. 35 ns

Answer : b)


  1. A thread is usually defined as a “light weight process” because an operating system (OS) maintains smaller data structures for a thread than for a process. In relation to this, which of the following is TRUE? [GATE – 2011]

a. On per-thread basis, the OS maintains only CPU register state
b. The OS does not maintain a separate stack for each thread
c. On per-thread basis, the OS does not maintain virtual memory state
d. On per thread basis, the OS maintains only scheduling and accounting information

Answer : c)


  1. Let the time taken to switch between user and a kernel modes of execution be t1 while the time taken to switch between two processes be t2. Which of the following : is TRUE? [GATE – 2011]

a. (t1) > (t2)
b. (t1) = (t2)
c. Nothing can be said about the relation between t1 and t2
d. (t1) < (t2)

Answer : d)


  1. Consider the following table of arrival time and burst time for three processes P0, P1 and P2.
ProcessArrival TimeBurst Time
P00 ms9 ms
P11 ms4 ms
P22 ms9 ms

The pre-emptive shortest job first scheduling algorithm is used. Scheduling is carried out only at arrival or at completion of processes. What is the average waiting time for the three processes?  [GATE – 2011]

a. 5.0 ms
b. 4.33 ms
c. 6.33 ms
d. 7.33 ms

Answer : a)
Operating System |Gate-2011|


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