Operating System |Gate-2011|
- 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)
- 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)
- 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)
- Consider the following table of arrival time and burst time for three processes P0, P1 and P2.
| Process | Arrival Time | Burst Time |
| P0 | 0 ms | 9 ms |
| P1 | 1 ms | 4 ms |
| P2 | 2 ms | 9 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|