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Recent questions and answers in Operating System

1 vote
2 answers
1
memory management
A computer whose processes have 1024 pages in their address spaces keeps its page tables in memory. The overhead required for reading a word from the page table is 500 nsec. To reduce this overhead, the computer has an associative memory which holds 32 (virtual page, ... frame) pairs and can do look up in 100 nsec. What hit rate is needed to reduce the mean overhead to 200 nsec?
A computer whose processes have 1024 pages in their address spaces keeps its page tables in memory. The overhead required for reading a word from the page table is 500 nsec. To reduce this overhead, the computer has an associative memory which holds 32 (virtual page, physical page frame) pairs and can do look up in 100 nsec. What hit rate is needed to reduce the mean overhead to 200 nsec?
answered 10 hours ago in Operating System sanjaysharmarose 722 views
0 votes
2 answers
4
synchronisation
The above synchronisation procedure satisfies 1. Mutual exclusion is guranteed 2.Progress is not guranteed 3.Bounded wait is not guranteed 4Deadlock may occur I am getting all of the above. Is it correct?
The above synchronisation procedure satisfies 1. Mutual exclusion is guranteed 2.Progress is not guranteed 3.Bounded wait is not guranteed 4Deadlock may occur I am getting all of the above. Is it correct?
answered Oct 19 in Operating System sachin486 268 views
41 votes
6 answers
5
GATE1990-7-b
In a two-level virtual memory, the memory access time for main memory, $t_{M}=10^{-8}$ sec, and the memory access time for the secondary memory, $t_D=10^{-3}$ sec. What must be the hit ratio, $H$ such that the access efficiency is within $80$ percent of its maximum value?
In a two-level virtual memory, the memory access time for main memory, $t_{M}=10^{-8}$ sec, and the memory access time for the secondary memory, $t_D=10^{-3}$ sec. What must be the hit ratio, $H$ such that the access efficiency is within $80$ percent of its maximum value?
answered Oct 19 in Operating System kalin 8.2k views
2 votes
2 answers
6
MadeEasy Test Series: Operating System - Semaphore
Consider program for P1 and P2: Here, m and n are binary semaphore variables whose values are initially initialized to 1. x and y are shared resources whose values are initialized to 0. Which of the following holds by above processes ... B :-Deadlock and race condition C :-No deadlocks and no race condition D:- Race condition and no deadlock
Consider program for P1 and P2: Here, m and n are binary semaphore variables whose values are initially initialized to 1. x and y are shared resources whose values are initialized to 0. Which of the following holds by above processes? A :- Deadlock and no mutual exclusion B :-Deadlock and race condition C :-No deadlocks and no race condition D:- Race condition and no deadlock
answered Oct 18 in Operating System indra kumar sahu 748 views
17 votes
3 answers
7
GATE1992-02-xi
02. Choose the correct alternatives (more than one may be correct) and write the corresponding letters only: (xi) A computer system has $6$ tape devices, with n processes competing for them. Each process may need $3$ tape drives. The maximum value of n for which the system is guaranteed to be deadlock-free is: $2$ $3$ $4$ $1$
02. Choose the correct alternatives (more than one may be correct) and write the corresponding letters only: (xi) A computer system has $6$ tape devices, with n processes competing for them. Each process may need $3$ tape drives. The maximum value of n for which the system is guaranteed to be deadlock-free is: $2$ $3$ $4$ $1$
answered Oct 14 in Operating System vipin.gautam1906 1.4k views
0 votes
2 answers
8
NIELIT 2017 DEC Scientific Assistant A - Section B: 37
How many times the word "PROCESS" will be printed when executing the following program ? main(){ printf("PROCESS"); fflush(); fork(); fork(); } $8$ $4$ $6$ $7$
How many times the word "PROCESS" will be printed when executing the following program ? main(){ printf("PROCESS"); fflush(); fork(); fork(); } $8$ $4$ $6$ $7$
answered Oct 13 in Operating System habedo007 160 views
43 votes
5 answers
9
GATE2007-IT-26
Consider $n$ jobs $J_1, J_2 \dots J_n$ such that job $J_i$ has execution time $t_i$ and a non-negative integer weight $w_i$. The weighted mean completion time of the jobs is defined to be $\frac{\sum_{i=1}^{n}w_iT_i}{\sum_{i=1}^{n}w_i}$, ... of the jobs? Non-decreasing order of $t_i$ Non-increasing order of $w_i$ Non-increasing order of $w_it_i$ Non-increasing order of $w_i/t_i$
Consider $n$ jobs $J_1, J_2 \dots J_n$ such that job $J_i$ has execution time $t_i$ and a non-negative integer weight $w_i$. The weighted mean completion time of the jobs is defined to be $\frac{\sum_{i=1}^{n}w_iT_i}{\sum_{i=1}^{n}w_i}$ ... time of the jobs? Non-decreasing order of $t_i$ Non-increasing order of $w_i$ Non-increasing order of $w_it_i$ Non-increasing order of $w_i/t_i$
answered Oct 11 in Operating System thewolf 7.1k views
1 vote
1 answer
10
made easy test
A system has 10 identical resources and N processes competing for them. Each process can request at most 3 resources but by grouping of first 3 processes needs only 6 resources. Then, the maximum value of ‘N is ______?
A system has 10 identical resources and N processes competing for them. Each process can request at most 3 resources but by grouping of first 3 processes needs only 6 resources. Then, the maximum value of ‘N is ______?
answered Oct 11 in Operating System sachin486 118 views
25 votes
3 answers
11
GATE1996-1.20, ISRO2008-56
Which of the following is an example of spooled device? A line printer used to print the output of a number of jobs A terminal used to enter input data to a running program A secondary storage device in a virtual memory system A graphic display device
Which of the following is an example of spooled device? A line printer used to print the output of a number of jobs A terminal used to enter input data to a running program A secondary storage device in a virtual memory system A graphic display device
answered Oct 9 in Operating System Cerium Bwaz 5.6k views
37 votes
9 answers
13
GATE1997-6.8
Each Process $P_i$, i = $1....9$ is coded as follows repeat P(mutex) {Critical section} V(mutex) forever The code for $P_{10}$ is identical except it uses V(mutex) in place of P(mutex). What is the largest number of processes that can be inside the critical section at any moment? $1$ $2$ $3$ None
Each Process $P_i$, i = $1....9$ is coded as follows repeat P(mutex) {Critical section} V(mutex) forever The code for $P_{10}$ is identical except it uses V(mutex) in place of P(mutex). What is the largest number of processes that can be inside the critical section at any moment? $1$ $2$ $3$ None
answered Oct 7 in Operating System vipin.gautam1906 9.3k views
162 votes
11 answers
14
GATE2008-67
A processor uses $36$ bit physical address and $32$ bit virtual addresses, with a page frame size of $4$ Kbytes. Each page table entry is of size $4$ bytes. A three level page table is used for virtual to physical address translation, where the virtual address is used as follows: ... page tables are respectively $\text{20,20,20}$ $\text{24,24,24}$ $\text{24,24,20}$ $\text{25,25,24}$
A processor uses $36$ bit physical address and $32$ bit virtual addresses, with a page frame size of $4$ Kbytes. Each page table entry is of size $4$ ... level page tables are respectively $\text{20,20,20}$ $\text{24,24,24}$ $\text{24,24,20}$ $\text{25,25,24}$
answered Oct 6 in Operating System Pawan007 36.6k views
0 votes
1 answer
16
Galvin Edition 9 Exercise 4 Question 2 (Page No. 191)
What are two differences between user-level threads and kernel-level threads ? Under what circumstances is one type better than the other ?
What are two differences between user-level threads and kernel-level threads ? Under what circumstances is one type better than the other ?
answered Oct 6 in Operating System Himanshu Kumar Gupta 37 views
3 votes
3 answers
17
ISRO2020-30
Consider the following page reference string. $1\ 2\ 3\ 4\ 2\ 1\ 5\ 6\ 2\ 1\ 2\ 3\ 7\ 6\ 3\ 2\ 1\ 2\ 3\ 6\ $ What are the minimum number of frames required to get a single page fault for the above sequence assuming LRU replacement strategy? $7$ $4$ $6$ $5$
Consider the following page reference string. $1\ 2\ 3\ 4\ 2\ 1\ 5\ 6\ 2\ 1\ 2\ 3\ 7\ 6\ 3\ 2\ 1\ 2\ 3\ 6\ $ What are the minimum number of frames required to get a single page fault for the above sequence assuming LRU replacement strategy? $7$ $4$ $6$ $5$
answered Oct 6 in Operating System Mohnish 1.2k views
2 votes
1 answer
18
true false statment, i-node,FAT
Reading a random location in a big file is faster in i-node based file systems than in FAT file systems. True or False?
Reading a random location in a big file is faster in i-node based file systems than in FAT file systems. True or False?
answered Oct 5 in Operating System sachin486 152 views
5 votes
6 answers
19
Deadlock
Consider two processes P1 and P2, each needed 3 resources 1, 2 and 3 in a database. If each processes ask them in any order, then the number of ways possible in which system is guaranteed to be deadlock free ________. Given answer is 6. I am getting 12.
Consider two processes P1 and P2, each needed 3 resources 1, 2 and 3 in a database. If each processes ask them in any order, then the number of ways possible in which system is guaranteed to be deadlock free ________. Given answer is 6. I am getting 12.
answered Oct 5 in Operating System sachin486 2.2k views
12 votes
3 answers
20
Consider two processes, P and Q, each need three records,
Consider two processes, P and Q, each need three records, R1, R2. and R3, in a database. If P asks for them in any order R1, R2, R3, and Q asks for them in any order, What fraction of all the combinations are guaranteed to be deadlock free? $\frac{1}{3}$ $\frac{2}{3}$ $\frac{1}{6}$
Consider two processes, P and Q, each need three records, R1, R2. and R3, in a database. If P asks for them in any order R1, R2, R3, and Q asks for them in any order, What fraction of all the combinations are guaranteed to be deadlock free? $\frac{1}{3}$ $\frac{2}{3}$ $\frac{1}{6}$
answered Oct 5 in Operating System sachin486 1.6k views
1 vote
4 answers
21
NIELIT 2016 MAR Scientist C - Section C: 7
In real-time operating systems, which of the following is the most suitable scheduling scheme? round-robin first-come-first-served preemptive random scheduling
In real-time operating systems, which of the following is the most suitable scheduling scheme? round-robin first-come-first-served preemptive random scheduling
answered Oct 5 in Operating System nagasudheer 320 views
2 votes
4 answers
22
The total time reuired to load the program from Disk
A program of size 64 MB is stored on disk which supports an average seek time of 32ms and rotation time of 20ms . Page size is 4MB and track size is 32MB . If the page of the program are countiguously placed on DIsk then the toatal time required to load the program from Disk in msec is ______
A program of size 64 MB is stored on disk which supports an average seek time of 32ms and rotation time of 20ms . Page size is 4MB and track size is 32MB . If the page of the program are countiguously placed on DIsk then the toatal time required to load the program from Disk in msec is ______
answered Oct 4 in Operating System sachin486 766 views
4 votes
2 answers
23
UGCNET-June2015-III: 53
In _____ allocation method for disk block allocation in a file system, insertion and deletion of blocks in a file is easy Index Linked Contiguous Bit Map
In _____ allocation method for disk block allocation in a file system, insertion and deletion of blocks in a file is easy Index Linked Contiguous Bit Map
answered Oct 4 in Operating System sachin486 1.7k views
37 votes
11 answers
24
GATE2009-33
The enter_CS() and leave_CS() functions to implement critical section of a process are realized using test-and-set instruction as follows: void enter_CS(X) { while(test-and-set(X)); } void leave_CS(X) { X = 0; } In the above solution, $X$ is a memory location associated with ... at the same time Which of the above statements are TRUE? (I) only (I) and (II) (II) and (III) (IV) only
The enter_CS() and leave_CS() functions to implement critical section of a process are realized using test-and-set instruction as follows: void enter_CS(X) { while(test-and-set(X)); } void leave_CS(X) { X = 0; } In the above solution, $X$ is a memory location associated with the $CS$ ... $CS$ at the same time Which of the above statements are TRUE? (I) only (I) and (II) (II) and (III) (IV) only
answered Oct 1 in Operating System Madhab 10.7k views
2 votes
2 answers
25
NIELIT 2017 OCT Scientific Assistant A (IT) - Section B: 15
Consider a system having $’m’$ resources of the same type. These resources are shared by $3$ processes $A,B,C;$ which have peak time demands of $3,4,6$ respectively. The minimum value of $’m’$ that ensures that deadlock will never occur is $11$ $12$ $13$ $14$
Consider a system having $’m’$ resources of the same type. These resources are shared by $3$ processes $A,B,C;$ which have peak time demands of $3,4,6$ respectively. The minimum value of $’m’$ that ensures that deadlock will never occur is $11$ $12$ $13$ $14$
answered Oct 1 in Operating System Ajay_777 127 views
0 votes
1 answer
26
File System
Is RAID structure in syllabus in operating system ???
Is RAID structure in syllabus in operating system ???
answered Oct 1 in Operating System Nitinkumar.097 52 views
1 vote
2 answers
27
Made easy workbook operating system
Consider the organisation of a UNIX file as represented by the inode. Assume that there are 12 block pointers and a singly,doubly and triply indirect pointer in each inode. Further assume that the system block size and the disk sector are both 8 KB. The disk ... accesses are required to access the byte position 13423826 of the file? (A) 1 (B) 2 (C) 4 (D) 8
Consider the organisation of a UNIX file as represented by the inode. Assume that there are 12 block pointers and a singly,doubly and triply indirect pointer in each inode. Further assume that the system block size and the disk sector are both 8 KB. The disk pointer is 32 bits and ... how many disk accesses are required to access the byte position 13423826 of the file? (A) 1 (B) 2 (C) 4 (D) 8
answered Oct 1 in Operating System sachin486 338 views
10 votes
4 answers
28
fork() using Tree structure
How many times ‘4’ will be printed ? int main() { if (fork() && (!fork())) { if (fork() || fork()) { fork(); } } printf("4 "); return 0; } How to approach these kind of questions using Tree structure ??
How many times ‘4’ will be printed ? int main() { if (fork() && (!fork())) { if (fork() || fork()) { fork(); } } printf("4 "); return 0; } How to approach these kind of questions using Tree structure ??
answered Sep 29 in Operating System learner 2102 1k views
1 vote
1 answer
29
Number of disk block accesses.
A file system uses continuous allocation to store data. What is the number of disk block accesses required to fetch n blocks of data ? Is it 1 or n?
A file system uses continuous allocation to store data. What is the number of disk block accesses required to fetch n blocks of data ? Is it 1 or n?
answered Sep 29 in Operating System sachin486 231 views
32 votes
4 answers
30
GATE2001-2.21
Consider a machine with $64$ MB physical memory and a $32$-bit virtual address space. If the page size s $4$ KB, what is the approximate size of the page table? $\text{16 MB}$ $\text{8 MB}$ $\text{2 MB}$ $\text{24 MB}$
Consider a machine with $64$ MB physical memory and a $32$-bit virtual address space. If the page size s $4$ KB, what is the approximate size of the page table? $\text{16 MB}$ $\text{8 MB}$ $\text{2 MB}$ $\text{24 MB}$
answered Sep 29 in Operating System learner 2102 13.7k views
1 vote
3 answers
31
NIELIT 2017 July Scientist B (CS) - Section B: 38
A system contains three programs and each requires three tape units for its operation. The minimum number of tape units which the system must have such that deadlocks never arise is _________. $6$ $7$ $8$ $9$
A system contains three programs and each requires three tape units for its operation. The minimum number of tape units which the system must have such that deadlocks never arise is _________. $6$ $7$ $8$ $9$
answered Sep 28 in Operating System nagasudheer 130 views
5 votes
4 answers
32
What is the average TAT??
Consider the processes P1, P2, P3 arrived in the sequence P2, P3, P1 and the burst time of the processes are 3, 3, 24 respectively. What is the average TAT??
Consider the processes P1, P2, P3 arrived in the sequence P2, P3, P1 and the burst time of the processes are 3, 3, 24 respectively. What is the average TAT??
answered Sep 28 in Operating System nagasudheer 2k views
3 votes
3 answers
33
why is the below state although being unsafe not leading to deadlock ?
I got the state to be unsafe since Available is (1,1) which can't satisfy the need of any process so why is not deadlock ?
I got the state to be unsafe since Available is (1,1) which can't satisfy the need of any process so why is not deadlock ?
answered Sep 28 in Operating System Mohnish 330 views
1 vote
2 answers
34
Finding maximum size of file
Given answer: 128 Please explain how to solve this problem
Given answer: 128 Please explain how to solve this problem
answered Sep 28 in Operating System sachin486 228 views
54 votes
4 answers
35
GATE2003-79
A processor uses $\text{2-level}$ page tables for virtual to physical address translation. Page tables for both levels are stored in the main memory. Virtual and physical addresses are both $32$ bits wide. The memory is byte addressable. For virtual to physical address translation, the $10$ ... the page tables of this process is $\text{8 KB}$ $\text{12 KB}$ $\text{16 KB}$ $\text{20 KB}$
A processor uses $\text{2-level}$ page tables for virtual to physical address translation. Page tables for both levels are stored in the main memory. Virtual and physical addresses are both $32$ bits wide. The memory is byte addressable. For virtual to physical address translation, the $10$ most ... the page tables of this process is $\text{8 KB}$ $\text{12 KB}$ $\text{16 KB}$ $\text{20 KB}$
answered Sep 27 in Operating System Gupta731 10.7k views
0 votes
1 answer
36
Andrew S. Tanenbaum (OS) Edition 4 Exercise 3 Question 41 (Page No. 259)
A computer provides each process with $65,536$ bytes of address space divided into pages of $4096$ bytes each. A particular program has a text size of $32,768$ bytes, a data size of $16,386$ bytes, and a stack size of ... it then fit? Each page must contain either text, data, or stack, not a mixture of two or three of them.
A computer provides each process with $65,536$ bytes of address space divided into pages of $4096$ bytes each. A particular program has a text size of $32,768$ bytes, a data size of $16,386$ bytes, and a stack size of $15,870$ bytes. Will this program fit in the ... were $512$ bytes, would it then fit? Each page must contain either text, data, or stack, not a mixture of two or three of them.
answered Sep 27 in Operating System sachin486 62 views
58 votes
11 answers
38
GATE2014-2-33
A computer has twenty physical page frames which contain pages numbered $101$ through $120$. Now a program accesses the pages numbered $\text{1, 2, ..., 100}$ in that order, and repeats the access sequence THRICE. Which one of the following ... faults as the optimal page replacement policy for this program? Least-recently-used First-in-first-out Last-in-first-out Most-recently-used
A computer has twenty physical page frames which contain pages numbered $101$ through $120$. Now a program accesses the pages numbered $\text{1, 2, ..., 100}$ in that order, and repeats the access sequence THRICE. Which one of the following page ... faults as the optimal page replacement policy for this program? Least-recently-used First-in-first-out Last-in-first-out Most-recently-used
answered Sep 27 in Operating System vipin.gautam1906 12.7k views
17 votes
6 answers
39
GATE1999-20-a
A certain processor provides a 'test and set' instruction that is used as follows: TSET register, flag This instruction atomically copies flag to register and sets flag to $1$. Give pseudo-code for implementing the entry and exit code to a critical region using this instruction.
A certain processor provides a 'test and set' instruction that is used as follows: TSET register, flag This instruction atomically copies flag to register and sets flag to $1$. Give pseudo-code for implementing the entry and exit code to a critical region using this instruction.
answered Sep 27 in Operating System Mohnish 1.9k views
1 vote
2 answers
40
Virtual Memory
Which of the following is true? A. If the page size increases page fault rate may also increase. B. Multi-level paging optimizes program execution time. C. Dynamic linking increases program execution time.Correct Option D. TLB is a software data structure.
Which of the following is true? A. If the page size increases page fault rate may also increase. B. Multi-level paging optimizes program execution time. C. Dynamic linking increases program execution time.Correct Option D. TLB is a software data structure.
answered Sep 26 in Operating System sachin486 414 views
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