Recent questions and answers in Operating System

0 votes

1 answer

1

Logical structure of directory
Are the logical level of directory I.e. Single,two level,tree structure directory ... in GATE SYLLABUS 2019

answered 11 hours ago in Operating System by cool_dude (47 points) | 13 views

+2 votes

1 answer

2

[Ace test series] OS

answered 13 hours ago in Operating System by arungate (419 points) | 64 views

0 votes

0 answers

3

UGCNET-NOV2017-III-51
User level threads are threads that are visible to the programmer and are unknown to the kernel. The operating system kernel supports and manages kernel level threads. Three different types of models relate user and kernel level threads. Which of the following statements is/are true ? (a) (i ... is false; (b) is true (3) Both (a) and (b) are true (4) Both (a) and (b) are false

asked 19 hours ago in Operating System by Roma_nagpal (115 points) | 11 views

0 votes

0 answers

4

Operating System ( Memory Management)
In one of the question from 2 level paging , they asked "What is the space overhead needed to translate virtual address to physical address of an instruction or data unit ? " Please explain what is space overhead in this context and how to calculate it.

asked 21 hours ago in Operating System by HeadShot (27 points) | 11 views

0 votes

1 answer

5

Memory mapped files
Please explain the concept of memory mapped files in OS. Is it really in GATE 2019 Syllabus?

answered 2 days ago in Operating System by MrPeppermint (413 points) | 16 views

0 votes

1 answer

6

ISI mtech CS Interview
Provide a synchronizing mechanism using semaphores such that a tiger and an elephant are not allowed to drink water from a pond simultaneously whereas more than one tiger or more than one elephant can.

answered 3 days ago in Operating System by MrPeppermint (413 points) | 27 views

0 votes

1 answer

7

UGCNET-Nov-2017-III-52
Consider a system with five processes P0 through P4 and three resource types A, B and C. Resource type A has seven instances, resource type B has two instances and resource type C has six instances suppose at time T0 we have the following allocation. Process ... we claim that system is __________. (1) Semaphore (2) Deadlock State (3) Circular Wait (4) Not in deadlock state

answered 3 days ago in Operating System by MrPeppermint (413 points) | 50 views

0 votes

1 answer

8

OS Kernel
Please explain each point. My assumptions are; 1.kernel must save the register values.It should be FALSE as it can be the case if the process is terminated.Thus, no need to save. 2.kernel must close the files. Explain this point in both the cases(the ... has not dealt with registers earlier.Thus, no need to restore. 4.kernel must save the content of memory onto disk. Explain this too.

answered 3 days ago in Operating System by MrPeppermint (413 points) | 84 views

0 votes

1 answer

9

Scheduling algorithms
There are 10 different processes running on a workstation. Idle processes are waiting for an input event in the input queue. Busy processes are scheduled with the Round-Robin timesharing method. Which out of the following quantum times is the best value for small response times, ... processes have a short runtime, e.g. less than 10ms ? a)TQ=15ms b)TQ=40ms c)TQ=50ms D)TQ=45ms

answered 4 days ago in Operating System by eyeamgj Active (2.4k points) | 23 views

0 votes

1 answer

10

Virtual memory
How does the virtual memory separates the logical memory as perceived by users from physical memory? Is it because we can load program with larger address space then physical memory but still we need physical memory to load our pages don't we ? Then what does the above statement actually trying to convey ?

answered 4 days ago in Operating System by srestha Veteran (86.9k points) | 27 views

+17 votes

5 answers

11

GATE1996-2.18
A $1000$ $\text{Kbyte}$ memory is managed using variable partitions but no compaction. It currently has two partitions of sizes $200$ $\text{Kbyte}$ and $260$ $\text{Kbyte}$ respectively. The smallest allocation request in $\text{Kbyte}$ that could be denied is for $151$ $181$ $231$ $541$

answered 4 days ago in Operating System by krishn.jh Junior (505 points) | 3.1k views

+1 vote

0 answers

12

Hierarchical Page Table
Given 64 bit logical space, Page Size = $4KB$. Do the three level paging? My Solution:- 1. Since address space is =$ 2^{64} Bytes$ Page size = $2^{12}$ Bytes. Number of entries in third level Page table is :- $2^{64} / 2^{12}$ = $2^ ... at three levels as:- $1st$ level $2nd$ level $3rd$ level Offset $ 32$ $10$ $10$ $12$ Please explain how did they find this out ? Please :)

asked 5 days ago in Operating System by Na462 Active (3.3k points) | 66 views

0 votes

0 answers

13

Memory Management
I want to know the difference between TLB, page table and cache. If in tlb its a hit then we don't access anything,, we just give the required page to the cpu.. But if it is a miss then we access page tables and cache.. If cache is a hit then ... and give the required page to the cpu. Can you plz tell me where am I wrong. Because the questions are not getting solved by this logic. [closed]

asked 5 days ago in Operating System by Iqra Islam (37 points) | 26 views

+1 vote

2 answers

14

Paging
For a computer architecture with multi level paging, a page size of $4 \hspace{0.1cm}KB$, and $64 \hspace{0.1cm} bit$ Physical and Virtual address: What is the smallest possible size for a page table entry, rounded up to a power of $2$? using your result ... into a single page, How many levels of Page tables would be required to completely map the $64 \hspace{0.1cm} bit$ virtual space?

answered 6 days ago in Operating System by srestha Veteran (86.9k points) | 105 views

+1 vote

1 answer

15

ISRO 2013
Consider the following process and resource requirement of each process. Type 1 Type 2 Process Used Max Used Max P1 1 2 1 3 P2 1 3 1 2 P3 2 4 1 4 Predict the state of this system, assuming that there are a total of 5 instances of resource ... of other process.Actually this system is in unsafe.but result of this unsafe condition is deadlock.can anyone help me to solve this confusion??

answered Jun 17 in Operating System by arungate (419 points) | 32 views

0 votes

0 answers

16

Question from my university's exam
For disk size of $768 \hspace{0.1cm}MB$ and block size of $384 \hspace{0.1cm} bytes$ what would be the bitmap size in bytes(as a power of $2$) iI represented $768 \hspace{0.1cm} MB$ as $3*2^{28}$ and $384$ as $3*2^7$ and then $\dfrac{3*2^ ... already in bytes, after all MB has $2^{20} \hspace{0.1cm} bytes$ so the answer $2^{21}$ should already be in bytes, right?

asked Jun 17 in Operating System by jj (7 points) | 10 views

+1 vote

1 answer

17

Virtual Memory
A demand paging system takes 250 time units to service a page fault and 450 time units to replace a dirty page. Memory access time is 10 time units. The probability of page faults is 0.3. In case of a page fault, the probability of page being dirty is 0.06. The average access time is ?

answered Jun 16 in Operating System by Prateek Raghuvanshi Active (3.9k points) | 26 views

0 votes

0 answers

18

Gate -1993
Number of tracks =200 Disk Rotation Speed=2400rpm Track storage capacity=62,500 bits What will be the average latency and data transfer rate of this device ?

asked Jun 15 in Operating System by Phlegmatic (177 points) | 10 views

0 votes

2 answers

19

#test series
Consider a machine with byte addressable memory 32 bits virtual addresses, 32 bits physical addresses and 4 KB page size. If a two-level page table system is used where each page table occupies one page and page table entries of 4 B each, then the memory overhead for this machine is ________ KB please explain.

answered Jun 15 in Operating System by MrPeppermint (413 points) | 24 views

0 votes

1 answer

20

#fork
How to solve such type of questions using tree I am having doubt in these types from where i can practice this type of question and can clear my concept

answered Jun 15 in Operating System by Shaik Masthan Active (2.5k points) | 42 views

0 votes

0 answers

21

Gatesyllabus
which topics cover under file system?

asked Jun 15 in Operating System by pranavpr9 (7 points) | 13 views

0 votes

0 answers

22

Difference between cylinder and tracks
I am getting confused with these two terms cylinder and tracks a) Is it cylinder = tracks ? b) How does addressing works in terms of surface and cylinder , track and sector https://gateoverflow.in/1337/gate2009-51

asked Jun 13 in Operating System by ejaz (175 points) | 20 views

0 votes

1 answer

23

cpu utilisation topic in os
A process spends 30% of its execution time waiting for completion of operation. If there are 5 processes in memory at once, then the probability of CPU time utilized is _______ %. (Assume all operations are overlapped).

answered Jun 13 in Operating System by Shaik Masthan Active (2.5k points) | 21 views

+6 votes

2 answers

24

UGCNET-Dec2013-II-46
Consider a preemptive priority based scheduling algorithm based on dynamically changing priority. Larger priority number implies higher priority. When the process is waiting for CPU in the ready queue (but not yet started execution), its priority changes at a rate a=2. When it starts running, its ... respectively be 4, 5, 7 and 8 8, 2, 7 and 5 2, 5, 7 and 8 8, 2, 5 and 7

answered Jun 12 in Operating System by Rams B (123 points) | 693 views

+1 vote

0 answers

25

Doubt
Well I haven't seen lot of questions on Monitors in OS from synchronization technique is it in GATE 2019 Syllabus ?

asked Jun 11 in Operating System by Na462 Active (3.3k points) | 32 views

+6 votes

2 answers

26

ISI2013-CS-5a
Suppose that an operating system provides two functions, $block()$ which puts the calling process on the blocked queue, and $wakeup(P)$ which moves process $P$ to the runnable queue if it is currently on the blocked queue (otherwise, its behaviour is unpredictable). ... should show the initialisation of the semaphore(s), and the calls to $wait()$ and $signal()$ made by $A$ and $B$.

answered Jun 11 in Operating System by krishn.jh Junior (505 points) | 218 views

0 votes

1 answer

27

#deadlock

answered Jun 11 in Operating System by Shaik Masthan Active (2.5k points) | 15 views

0 votes

0 answers

28

DOUBT ON ANSWER OF PREVIOUS YEAR
https://gateoverflow.in/8227/gate2015-1-30 as per the language of question the answer should be -10?????

asked Jun 11 in Operating System by eyeamgj Active (2.4k points) | 29 views

+21 votes

4 answers

29

GATE2010-23
Consider the methods used by processes P1 and P2 for accessing their critical sections whenever needed, as given below. The initial values of shared boolean variables S1 and S2 are randomly assigned. Method used by P1 Method used by P2 ... ? Mutual excusion but not progress Progress but not mutual exclusion Neither mutual exclusion nor progress Both mutual exclusion and progress

answered Jun 11 in Operating System by krishn.jh Junior (505 points) | 3k views

0 votes

1 answer

30

FCFS Disk Scheduling
Queue 98, 183, 37, 122, 14, 124, 65, 67 head starts at 53 Find total head movements

answered Jun 10 in Operating System by Kajal Khobragade Active (1.3k points) | 70 views

+1 vote

1 answer

31

Doubt on progress , bounded waiting and deadlock

answered Jun 9 in Operating System by Deepakk Poonia (Dee) Boss (13.2k points) | 37 views

0 votes

1 answer

32

Operating System
In a computer system, three files of size 11052 B, 4992 B and 5172 B need to be stored. For storing these files on disk, we can use either 100 B disk block or 200 B disk block. For each block used to store a file, 2 bytes of book ... data from a file, but not both. What is the total space required for storing the files using 100 B and 200 B disk blocks respectively___________

answered Jun 9 in Operating System by Deepakk Poonia (Dee) Boss (13.2k points) | 24 views

+17 votes

3 answers

33

GATE2006-06, ISRO2009-14
Consider three CPU-intensive processes, which require $10$, $20$ and $30$ time units and arrive at times $0$, $2$ and $6$, respectively. How many context switches are needed if the operating system implements a shortest remaining time first scheduling algorithm? Do not count the context switches at time zero and at the end. $1$ $2$ $3$ $4$

answered Jun 9 in Operating System by mehul vaidya Junior (993 points) | 3.1k views

+2 votes

2 answers

34

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.

answered Jun 9 in Operating System by Abbas2131 Active (1.8k points) | 72 views

0 votes

1 answer

35

How to write deadlock free operation using Semaphore P(S) and V(S)

answered Jun 9 in Operating System by MrPeppermint (413 points) | 45 views

+8 votes

2 answers

36

TIFR2015-B-14
Consider the following concurrent program (where statements separated by | | with-in cobegin-coend are executed concurrently). x:=1 cobegin x:= x + 1 || x:= x + 1 || x:= x + 1 coend Reading and writing of variables is atomic but evaluation of expressions is not atomic. The set of possible values ... 4 \right \}$ $\left \{2, 4 \right \}$ $\left \{ 2, 3 \right \}$ $\left \{2 \right \}$

answered Jun 8 in Operating System by Lone Wolf Junior (727 points) | 379 views

0 votes

1 answer

37

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?

answered Jun 8 in Operating System by sonveer tomar 1 Active (3k points) | 36 views

0 votes

1 answer

38

Context switching Doubt
when execution of one process is completed and other process is scheduled , Is it called Context switch ? I think , It is not Context switch, as according to wiki In computing, a context switch is the process of storing the state of a process ... back into memory. Hence answer to this previous year gate question must be 0 http://gateoverflow.in/885/gate2006-06-isro2009-14

answered Jun 8 in Operating System by MrPeppermint (413 points) | 25 views

+2 votes

1 answer

39

Galvin
The Following processes are being scheduled using a Premptive RR scheduling Alogrithm. Each Process is Assigned a numeric Proirity, with higher number indicating higher priority. In addition it also has ideal task which consumes no CPU Resources and is identified by Pidle. This task ... 10 105 A. Turn Around Time of Each Process ? B. Waiting time of Each Process ? C. CPU Utilization Rate ?

answered Jun 8 in Operating System by MrPeppermint (413 points) | 27 views

0 votes

1 answer

40

how to determing lenngh of next cpu burst ??

answered Jun 8 in Operating System by MrPeppermint (413 points) | 36 views

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score	score:10
answers	answers:2
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