Recent questions and answers in Operating System - GATE CSE Doubts

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Testbook Question
Consider below code , where integer k initialized to $0.$ while(k!=11){ k++; if(k%5==0) continue; fork(); } What is the total number of process created here?? while will be execute 1 to 10 and fork() will not execute for 5 and 10. So, my ans is $2^{8}=256$ but given ans 512. How?

asked 13 hours ago in Operating System by srestha (749 points) | 6 views

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Job Scheduler
As we know Job scheduler works on mainly 2 criteria - To maintain degree of multiprogramming and to maintain proper mixture of CPU bound and I/O bound processes and considering these 2 criteria, it will new process from New/Start to Ready State. So my question is how Job scheduler come to know that the process if CPU bound or I/O bound ???

asked 2 days ago in Operating System by lakshakar (6 points) | 8 views

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compiler construction
Construct LL (1) parsing table and verify whether it is LL (1). S→ a AB /ϵ A->1AC/0C B->0S C->1

answered 4 days ago in Operating System by premu (69 points) | 14 views

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EXTERNAL FRAGMENTATION SELF DOUBT
SUPPOSE THERE ARE THREE MEMORY BLOCKS OF SIZES 40 KB,55KB,70KB AND SUPPOSE FIXED PARTITION SCHEME A REQUEST OF PROCESS OF 80 KB WILL NOT BE SATISFIED IT IT CLEAR .MY DOUBT IS WILL THERE BE STILL EXTERNAL FRAGMENTATION ?

answered 4 days ago in Operating System by premu (69 points) | 14 views

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ISRO CS 2017-MAY
What is the output of the following program? main( ) { int a = 10; if ((fork ( ) == 0)) a++; printf (“%dn”, a ); } a) 10 and 11 b) 10 C) 11 D) 11 and 11

answered 4 days ago in Operating System by premu (69 points) | 18 views

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Threads in Operating Systems
why threads in different processes cannot share resources while threads within same process ?

asked Jun 19 in Operating System by Aadil Azad Khan (6 points) | 8 views

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Inter process communication
Consider the following two code fragments given below, (a) and (b): (a) main ( ) { int pfd[2], id; pipe (pfd); id=fork( ); //line n if (id==0) { // Child executing } else { //Parent executing } } (b) main ( ... ) after execution of line n for above code fragments. (ii) In which case, interprocess communication using pipe is possible between the parent and child process?

asked Jun 17 in Operating System by Tris Ravi (11 points) | 4 views

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Shell program
Write a program to create a process tree as shown in Figure below and print the process identifiers in Inorder traversal form. The height (depth) of the tree is a command line argument. The program should create simultaneously executing processes in the ... should not create an orphan process while execution. The parent process should also print the exit status of its child processes.

asked Jun 17 in Operating System by Tris Ravi (11 points) | 2 views

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C program using grep and cat command
Write C program for implementing cat < file1.c | grep #include | wc -l > file 2.

asked Jun 17 in Operating System by Tris Ravi (11 points) | 4 views

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OS DOUBT PROCESSS SYNCHRONIZATION
CONSIDER A CODE TO BE EXECUTED BY DIFFERENT PROCESS SIMULTANEOUSLY ,MUTEX =1 ,DOES THIS CODE SATISFY PROGRESS? P(MUTEX) CRITICAL SECTION V(MUTEX)

asked Jun 16 in Operating System by eyeamgj (44 points) | 4 views

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Synchronization
Can anyone tell from where to perfect topics – Synchronization and Concurrency in OS? Or how to become self efficient to solve questions in exam

asked Jun 14 in Operating System by prajjwalsingh_11 (16 points) | 7 views

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Operating system
Can anyone summarise all the possible formulas regarding Tlb (involving pagefaults,cache,dirty write etc)

asked Jun 14 in Operating System by sreejit007 (6 points) | 7 views

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Gate questions 2015(set-3) and 2007
Question 1: https://gateoverflow.in/8405/gate2015-3-10 Question 2: https://gateoverflow.in/1256/gate2007-58 What is the difference between this two questions? Why the answer is different? But the questions look like same. Please explain. Just name is changed in question. VarP instead of wants1 and VarQ instead of wants2. Rest all are same.

asked Jun 14 in Operating System by premu (69 points) | 5 views

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https://gateoverflow.in/12963/gate1998-7-b
https://gateoverflow.in/12963/gate1998-7-b here we are considering multicore cpu ?

asked Jun 14 in Operating System by shashank joshi (7 points) | 4 views

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Operating system principles book by Galvin
Is there a difference in 7th edition book and 9th edition book of Galvin OS If it has any than what? Do I need to buy 9th edition for gate preparation or 7th edition is fine. And how can I prepare from this book?

asked Jun 8 in Operating System by shiv_ka_ansh (6 points) | 3 views

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Binary Semaphores
Suppose we want to synchronize two concurrent processes P and Q using binary semaphores S, T and U: Process P: Process Q: P(S) W: P(T) X: P(U) Y: Print ‘a’ Print ‘a’; Print ‘b’ Print ‘b’; V(S) A: V(T) B: V(U) C: What should be written at W to avoid deadlock? (a) P(T) (b) P(U) (c) P(S) (d) Not possible to avoid deadlock

asked Jun 5 in Operating System by amare123 (6 points) | 8 views

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memory management application
Consider a movie player application that supports functions like play movie, skip forward x frames and skip backward x frames. Suggest a memory management policy that will be best suited for this application. (source: question 4.4 ) Ans is given as: A ... if we use Look-ahead as in paging, then this will perform equally well, if not better. Please comment on it.

asked Jun 5 in Operating System by reboot (7 points) | 4 views

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Self-Doubt In OS, Process Synchronization
Consider the following implementation of a general (counting) semaphore. This implementation assumes the existence of binary semaphore operations upb and downb implemented with a test-and-set instruction. Procedure UP( S : semaphore): downb( ... preemptive version) c) Priority (you may assign whatever priorities to the processes you wish) d) Round-Robin

asked Jun 5 in Operating System by Chinmay Agnihotri (13 points) | 8 views

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Self-Doubt In OS, Process Synchronization
Consider the following implementation of a general (counting) semaphore. This implementation assumes the existence of binary semaphore operations upb and downb implemented with a test-and-set instruction. Procedure UP( S : semaphore): downb( ... preemptive version) c) Priority (you may assign whatever priorities to the processes you wish) d) Round-Robin

asked Jun 5 in Operating System by Chinmay Agnihotri (13 points) | 2 views

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Threads Self Doubt IIT notes
User-level threads require non-blocking systems call i.e., a multithreaded kernel. Otherwise, the entire process will be blocked in the kernel, even if there are runnable threads left in the processes. For example, if one thread causes a page fault, ... kernel ? I cannot understand the relation between them, please help. link: IIT notes threads (last para of the page)

asked Jun 4 in Operating System by reboot (7 points) | 9 views

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Tannenbaum Chapter 2 Processes and Threads
Multiple jobs can run in parallel and finish faster than if they had run sequentially. Suppose that two jobs, each of which needs 5 minutes of CPU time, start simultaneously. How long will they last one take to complete if they run sequentially? How long if they ... in I/O = 5 + 20%*(5) = 6min instead of 6.25 minutes. What is the logic of 6.25 minutes?

asked Jun 3 in Operating System by AliH (11 points) | 8 views

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Software Design, Performance tuning of Job_Dispatcher

asked Jun 1 in Operating System by faseela45 (6 points) | 4 views

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Operating System Concepts (9th Ed) - Gagne, Silberschatz, and Galvin

answered May 30 in Operating System by Kushagra गुप्ता (415 points) | 29 views

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Page Faults in Operating Systems
If we can find an entry for the requested page in the page table, then are there any chances of page fault? If yes, then how? Thank you!

asked May 30 in Operating System by yagneshmb (6 points) | 32 views

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#Semaphore # vani test series #gate
[closed]

asked May 29 in Operating System by DEBANJAN GHOSH (7 points) | 17 views

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OS-William Stallings, 7-edition, Chapter-8, Page-351

asked May 28 in Operating System by Kushagra गुप्ता (415 points) | 29 views

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Deadlock operating sysytem
How to solve this? Plz provide detail solution.

asked May 28 in Operating System by Vink7389 (9 points) | 11 views

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Madeeasy test series

asked May 27 in Operating System by Ashish Thakor (7 points) | 15 views

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Dhamdhere Operating System Chapter 7 Example 7.5
First of all sorry for my english. I have a doubt: i suppose that the example of the textbook is incorrect. Why is the I/O time subracted from response time? Makes no sense. The example: An OS contains 10 identical processes that were ... (2+20)−10 ms = 210 ms because the process spends 10 ms in an I/O wait before receiving the next subrequest.

asked May 25 in Operating System by Lord Vincent (6 points) | 10 views

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Operating System
Is there any relation hold between internal and external fragmentation.? If there is internal fragmentation in memory so there can be external fragmentation exist and vice versa?

asked May 25 in Operating System by Vink7389 (9 points) | 9 views

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Opearatng system
Write a program in (C/C++) that visits every directory, starting with the current directory. [closed]

asked May 23 in Operating System by Bhavya1902 (7 points) | 9 views

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Assignment of the GATE Revision book
Consider three process, all arriving at time zero, with total execution time of 10, 20 and 30 units respectively. Each process spends the first 30% of execution time doing I/O, the next 40% of time doing computation, and the last 30% of ... Assume that all I/O operations can be overlapped as much as possible. For what percentage of does the CPU remain idle?

asked May 18 in Operating System by SharmaHoney (7 points) | 14 views

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#Made easy notes #Multilevel_paging
Consider a system using 2 level paging applicable.The page table has divided into 2K pages and each page is having 4K entries.The memory is word addressable and PAS =64MW which is divided into 16k frames.The page table entry size in both the table is 2W. Calculate Length of LA Length of PA 1st level page table size 2nd level page table size

asked May 17 in Operating System by Vink7389 (9 points) | 14 views

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Assignment of Nirma University
Suppose a process attempts to go to sleep on event A but has not yet executed the code in sleep(). At this point an interrupt occurs and due to which interrupt handler awakens all the processes asleep on event A. What will happen to the process mentioned above which was attempting to sleep but not slept yet? Is this dangerous situation? Is so, how can kernel avoid it?

asked May 13 in Operating System by mittshah (6 points) | 8 views

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Blocked or Waiting state
What happens when Process/Thread goes in blocked or waiting state..? Actually my primary question is I want to know if supposed some threads/ process may have acquired any locks / resources..then for some reason if they have to go to blocked / waiting state then ... sources for further read on this topic (Also tell if the point I am raising is also worth it or not..? )

asked May 13 in Operating System by Peter Smith (8 points) | 10 views

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Gate1999-2.12
Link for the question : Gate1999-2.12 My doubt is regarding $D$ option which states that : Invalidating TLB is required while context switching. Best answer also states that it is $true$ and a proper reasoning is mentioned. But just after the Best answer there ... ASID's ? And if not then both C and D can be the answer possible then. @ankitgupta.1729 @ShaikMasthan Please look into it

asked May 12 in Operating System by Kushagra गुप्ता (415 points) | 20 views

+1 vote

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Self-Doubt in OS Memory Management (William Stallings) [closed]

asked May 7 in Operating System by stevegates (20 points) | 15 views

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Self-doubt related to OS
What is the use of par-begin par-end / begin-end ? Are they just for theoretical purpose or do they have practical implementation ? From where I can study about them ? Are they still in use or something else has replaced them ? I want to know that how semaphores also play a role in these. Are they just theoretical or they have a practical implementation ?

asked May 6 in Operating System by stevegates (20 points) | 4 views

+1 vote

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GATE2020-CS-50 Video Solution
Consider the following set of processes, assumed to have arrived at time $0$. Consider the CPU scheduling algorithms Shortest Job First (SJF) and Round Robin (RR). For RR, assume that the processes are scheduled in the order$P_1, P_2, P_3, P_4$ ... of the difference between the average turnaround times (in ms) of SJF and RR (round off to $2$ decimal places is_______

answered Apr 30 in Operating System by amitkhurana512 (187 points) | 8 views

+1 vote

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GATE2020-CS-35 Video Solution
Consider the following five disk five disk access requests of the form (request id, cylinder number) that are present in the disk scheduler queue at a given time. $(P, 155), (Q,85), (R,110),(S, 30), (T,115)$ Assume the head is positioned at ... ,but before $T$. The head reverses its direction of movement between servicing of $Q$ and $P$. $R$ is serviced before $P$.

answered Apr 30 in Operating System by amitkhurana512 (187 points) | 8 views

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