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This quiz consists of questions from the Operating System for GATE 2019 preparation.
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Question 1 of 30
1. Question1 points
A process executes the following code
for(i=0;i<n;i++) for ();
The total number of child process created is____?
Question 2 of 30
2. Question1 points
Which of the following system calls results in the sending of SYN packets?
Question 3 of 30
3. Question1 points
A multilevel page table is preferred in comparison to a single level page table for translating virtual address to physical address because
Question 4 of 30
4. Question1 points
A CPU generates the 32-bit virtual address. The page size is 4 KB. The processor has a transition lookaside buffer(TLB) which can hold a total of 128-page table entries and is 4 way set associative. The minimum size of the TLB tag is_____.
Question 5 of 30
5. Question1 points
Consider a machine with 64 MB physical memory and 32-bit virtual address space. If the page size is 4KB, what is the approximate size of the page table?
Question 6 of 30
6. Question1 points
Consider the following policies for preventing deadlock in a system with mutually exclusive resources.
- Processes should acquire all their resources at the beginning of execution. If any resource is not available, all resources acquired so far are released
- The resources are numbered uniquely, and processes are allowed to request for resources only in increasing resource numbers
- The resources are numbered uniquely, and processes are allowed to request for resources only in decreasing resource numbers
- The resources are numbered uniquely. A process is allowed to request only for a resource with resource number larger than its currently held resources
Which of the above policies can be used for preventing deadlock?
Question 7 of 30
7. Question1 points
Let the page fault service time be 10 ms in a computer with average memory access time being 20 ns. If the one-page fault is generated for every 106 memory accesses, what is the effective access time for the memory?
Question 8 of 30
8. Question1 points
Identify the correct order in which a server process must invoke the function calls accept, bind, listen, and recv according to UNIX socket APL.
Question 9 of 30
9. Question1 points
A virtual memory system uses First In First Out (FIFO) page replacement policy and allocates a fixed number of frames to a process. Consider the following statements:
P: Increasing the number of page frames allocated to a process sometimes increases the page fault rate.
Q: Some programs do not exhibit locality of reference.
Which one of the following is TRUE?
Question 10 of 30
10. Question1 points
A process has been allocated 3-page frames. Assume that none of the pages of the process are available in the memory initially. The process makes the following sequence of page references (reference string):
1, 2, 1, 3, 7, 4, 5, 6, 3, 1
If optimal page replacement policy is used, how many page faults occur for the above reference string?
Question 11 of 30
11. Question1 points
Which of the following requires a device driver?
Question 12 of 30
12. Question1 points
A system uses FIFO policy for page replacement. It has 4-page frames with no pages loaded to begin with. The system first accesses 100 distinct pages in some order and then accesses the same 100 pages but now in the reverse order.
How many page faults will occur?
Question 13 of 30
13. Question1 points
In which one of the following page replacement algorithms it is possible for the page fault rate to increase even when the number of allocated frames increases?
Question 14 of 30
14. Question1 points
In which one of the following page replacement policies, Belady’s anomaly may occur?
Question 15 of 30
15. Question1 points
A process executes the code
The total number of child processes created is
Question 16 of 30
16. Question1 points
Consider the virtual page reference string
1, 2, 3, 2, 4, 1, 3, 2, 4, 1
on a demand paged virtual memory system running on a computer system that has a main memory size of 3-page frames which are initially empty. Let LRU, FIFO, and OPTIMAL denote the number of page faults under the corresponding page replacement policy. Then
Question 17 of 30
17. Question1 points
Let the time taken to switch between user and kernel modes of execution be t1 while the time taken to switch between two processes be t2.
Which of the following is TRUE?
Question 18 of 30
18. Question1 points
A system has 6 identical resources and N processes competing for them. Each process can request at most 2 resources. Which one of the following values of N could lead to a deadlock?
Question 19 of 30
19. Question1 points
Consider the main memory with five-page frames and the following sequence of page references: 3, 8, 2, 3, 9, 1, 6, 3, 8, 9, 3, 6, 2, 1, 3. Which one of the following is true with respect to page replacement policies First In First Out(FIFO) and Least Recently Used(LRU)?
Question 20 of 30
20. Question1 points
Consider six memory partitions of sizes 200 KB, 400 KB, 600 KB, 500 KB, 300 KB, and 250 KB, where KB refers to the kilobyte. These partitions need to be allotted to four processes of sizes 357 KB, 210 KB, 468 KB, and 491 KB in that order. If the best-fit algorithm is used, which partitions are NOT allotted to any process?
Question 21 of 30
21. Question1 points
A Unix style Inode has 10 direct pointers and one single, one double and one triple indirect pointers. The disk block size is 1 KB, the disk block address is 32 bit and 48-bit integers are used. What is the maximum possible file size?
Question 22 of 30
22. Question1 points
Consider a paging hardware with a TLB. Assume that the entire page table and all the pages are in the physical memory. It takes 10 milliseconds to search the TLB and 80 milliseconds to access the physical memory. If the TLB hit ratio is 0.6, the effective memory access time (in milliseconds) is _________.
Question 23 of 30
23. Question1 points
The essential content(s) in each entry of a page table is/are
Question 24 of 30
24. Question1 points
A computer handles several interrupt sources of which the following are relevant for this question.
- Interrupt from the CPU temperature sensor (raises interrupt if CPU temperature is too high)
- Interrupt from Mouse (raises interrupt if the mouse is moved or a button is pressed)
- Interrupt from Keyboard (raises interrupt when a key is pressed or released)
- Interrupt from Hard Disk (raises interrupt when a disk read is completed)
Which one of these will be handled at the HIGHEST priority?
Question 25 of 30
25. Question1 points
Consider a disk system with 100 cylinders. The request to access the cylinders occur in following sequence4, 34, 10, 7, 19, 73, 2, 15, 6, 20Assuming that the head is currently at cylinder 50, what is the time taken to satisfy all requests, if it takes 1 ms to move from one cylinder to adjacent on and shortest seek time first policy is used?
Question 26 of 30
26. Question1 points
The maximum number of processes that can be in the Ready state for a computer system with n CPUs is ____?
Question 27 of 30
27. Question1 points
The thread is usually defined as a lightweight 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?
Question 28 of 30
28. Question1 points
The data blocks of a very large file in the Unix file system are allocated using
Question 29 of 30
29. Question1 points
Which of the following is NOT true of deadlock prevention and deadlock avoidance schemes?
Question 30 of 30
30. Question1 points
Which of the following statements are true?
I. Shortest remaining time first scheduling may cause starvation
II. Preemptive scheduling may cause starvation
III. Round robin is better than FCFS in terms of response time