Recent questions and answers in Operating System

+30 votes

7 answers

1

GATE2007-58
Two processes, $P1$ and $P2$, need to access a critical section of code. Consider the following synchronization construct used by the processes: /* P1 */ while (true) { wants1 = true; while (wants2 == true); /* Critical Section */ ... bounded waiting. It requires that processes enter the critical section in strict alteration. It does not prevent deadlocks, but ensures mutual exclusion.

answered 5 hours ago in Operating System by JashanArora (93 points) | 5.4k views

+22 votes

8 answers

2

GATE1998-2.18, UGCNET-June2012-III-48
If an instruction takes $i$ microseconds and a page fault takes an additional $j$ microseconds, the effective instruction time if on the average a page fault occurs every $k$ instruction is: $i + \dfrac{j}{k}$ $i +(j\times k)$ $\dfrac{i+j}{k}$ $({i+j})\times {k}$

answered 1 day ago in Operating System by commenter commenter (321 points) | 3.5k views

0 votes

1 answer

3

Effective memory access time
Suppose: TLB lookup time = 20 ns TLB hit ratio = 80% Memory access time = 75 ns Swap page time = 500,000 ns 50% of pages are dirty OS uses a single level page table What is the effective access time (EAT) if we assume the page fault rate is 10%? Assume the cost toupdate the TLB, the page table, and the frame table (if needed) is negligible.

answered 1 day ago in Operating System by ysaurabh146 (17 points) | 99 views

0 votes

2 answers

4

MadeEasy Test Series: Operating System - Process Synchronization
P1 terminates but P2 does not P2 terminates but P1 does not Both P1 and P2 terminate Neither P1 nor P2 terminate

answered 2 days ago in Operating System by ysaurabh146 (17 points) | 98 views

+6 votes

4 answers

5

Question on process state transition
Answer to the above question is (C). I am unable to understand that how can a process in ready state can get blocked. Please give an explanation.

answered 2 days ago in Operating System by Shailendra_ (17 points) | 1k views

+5 votes

5 answers

6

GATE2019-17
The following C program is executed on a Unix/Linux system : #include<unistd.h> int main() { int i; for(i=0; i<10; i++) if(i%2 == 0) fork(); return 0; } The total number of child processes created is ________________ .

answered 3 days ago in Operating System by vikas001 (11 points) | 2.8k views

0 votes

1 answer

7

Galvin Edition 9 Exercise 9 Question 36 (Page No. 456)
A system provides support for user-level and kernel-level threads. The mapping in this system is one to one (there is a corresponding kernel thread for each user thread). Does a multithreaded process consist of $(a)$ a working set for the entire process or $(b)$ a working set for each thread ? Explain

answered 3 days ago in Operating System by satya753 (57 points) | 46 views

+15 votes

5 answers

8

GATE1993-7.9, UGCNET-Dec2012-III-41
Consider a system having m resources of the same type. These resources are shared by $3$ processes $A$,$B$, and $C$ which have peak demands of $3$, $4$ and $6$ respectively. For what value of m deadlock will not occur? $7$ $9$ $10$ $13$ $15$

answered 3 days ago in Operating System by shivam001 (271 points) | 8k views

+48 votes

5 answers

9

GATE2012-32
Fetch_And_Add(X,i) is an atomic Read-Modify-Write instruction that reads the value of memory location $X$, increments it by the value $i$, and returns the old value of $X$. It is used in the pseudocode shown below to implement a busy-wait ... can take on a non-zero value when the lock is actually available works correctly but may starve some processes works correctly without starvation

answered 4 days ago in Operating System by RutviNathvani13 (11 points) | 8.7k views

+41 votes

8 answers

10

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

answered 6 days ago in Operating System by KrantiKumari (11 points) | 7.6k views

+1 vote

2 answers

11

Segmentation
In segmented paging, is the paging applied on segment table or on segments?

answered Aug 15 in Operating System by sakharam Active (2.8k points) | 482 views

0 votes

1 answer

12

ISI2018-PCB-B8
Consider a $5$ ... $(in\ ns)$ needed to execute the program.

answered Aug 15 in Operating System by ritesh5040 (27 points) | 45 views

+21 votes

4 answers

13

GATE2005-71
Suppose $n$ processes, $P_1, \dots P_n$ share $m$ identical resource units, which can be reserved and released one at a time. The maximum resource requirement of process $P_i$ is $s_i$, where $s_i > 0$. Which one of the following is a sufficient condition for ensuring that deadlock does not ... $\displaystyle{\sum_{i=1}^n} \: s_i < (m \times n)$

answered Aug 13 in Operating System by Shailendra_ (17 points) | 3.3k views

+3 votes

3 answers

14

How to Find Data Transfer Rate?
Consider a disk pack with following specifications - 16 surfaces, 128 tracks/surface, 256 sector/track and 512Bytes/sector. Now, the disk is rotating at 3600RPM, what is the data transfer rate. Please be as elaborative and simplified in your approach of explaining! Thank you, all the nerds on this site!

answered Aug 4 in Operating System by raju paul (231 points) | 1.8k views

0 votes

2 answers

15

Stallings 6e Exercise-11.10 (page number-539) I/O Management
A 32-bit computer has two selector channels and one multiplexor channel. Each selector channel supports two magnetic disk and two magnetic tape units. The multiplexor channel has two line printers, two card readers, and ten VDT terminals ... reader 1.2 Kbytes/s VDT 1 Kbytes/s Estimate the maximum aggregate I/O transfer rate in this system

answered Aug 4 in Operating System by raju paul (231 points) | 33 views

0 votes

1 answer

16

Stallings 6e Exercise-11.12 (page no.-539) I/O Management RAID
Consider a 4-drive, 200GB-per-drive RAID array. What is the available data storage capacity for each of the RAID levels, 0, 1, 3, 4, 5, and 6?

answered Aug 4 in Operating System by raju paul (231 points) | 42 views

+3 votes

2 answers

17

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 ??

answered Aug 2 in Operating System by Manas Mishra Active (2.9k points) | 144 views

+1 vote

2 answers

18

Galvin
Assume that you have a page-reference string for a process with m frames (initially all empty). The page-reference string has length p; n distinct page numbers occur in it.Answer these questions for any page replacement algorithms: a. What is a lower bound on the number of page faults? b. What is an upper bound on the number of page faults?

answered Jul 30 in Operating System by KULDEEP SINGH 2 Junior (857 points) | 1.4k views

+1 vote

3 answers

19

Multilevel paging
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. How to calculate the size of 1st level page table & 2nd level page table(s) ? Also how to calculate memory overhead?

answered Jul 29 in Operating System by ayushsomani (215 points) | 620 views

0 votes

2 answers

20

Self Doubt:Paging
I have read that paging does not suffer from external fragmentation as the frames and the pages are all of the equal sizes, but when we store a last level page table in a frame at that time it may not fully occupy the frame. Similarly, if ... exceed a page size. Then there should be external fragmentation, right? So why is it said that paging does not have external fragmentation?

answered Jul 29 in Operating System by ayushsomani (215 points) | 118 views

+17 votes

4 answers

21

GATE2000-2.22
Suppose the time to service a page fault is on the average $10$ milliseconds, while a memory access takes $1$ microsecond. Then a $99.99\%$ hit ratio results in average memory access time of $1.9999$ milliseconds $1$ millisecond $9.999$ microseconds $1.9999$ microseconds

answered Jul 28 in Operating System by nadeshseen (83 points) | 4.6k views

+1 vote

2 answers

22

MadeEasy Test Series: Operating System - Page Replacement
Consider a demand paged memory system, page table is held in registers. It takes 800 nsec to service a page fault if empty page is available or replaced page is not modified and 950 nsec if the replaced page is modified, ... modified 85% of time and page faultrate is 20% then average memory access time is ________. (Upto 1 decimal place)

answered Jul 27 in Operating System by nadeshseen (83 points) | 181 views

+22 votes

4 answers

23

GATE1997-3.9
Thrashing reduces page I/O decreases the degree of multiprogramming implies excessive page I/O improve the system performance

answered Jul 27 in Operating System by mohan123 Junior (663 points) | 2.8k views

+1 vote

3 answers

24

MadeEasy Test Series: Operating System - Resource Allocation

answered Jul 27 in Operating System by SHRIHARI NAIK (17 points) | 67 views

+1 vote

1 answer

25

MadeEasy Subject Test 2019: Operating System - Virtual Memory

answered Jul 26 in Operating System by GATE2021 (25 points) | 77 views

+1 vote

1 answer

26

UGCNET-June-2019-II-47
The minimum number of page frames that must be allocated to a running process in a virtual memory environment is determined by page size physical size of memory the instruction set architecture number of processes in memory

answered Jul 26 in Operating System by ernarayansahu (11 points) | 43 views

+7 votes

3 answers

27

Demand Paging
Suppose: TLB lookup time = 20 ns TLB hit ratio = 80% memory access time = 75 ns swap page time = 500,000 ns 75% of pages are dirty OS uses a 3 level page table What is the effective access time (EAT) if we assume the page fault rate is 15% ?

answered Jul 26 in Operating System by ayushsomani (215 points) | 1.3k views

+1 vote

1 answer

28

Virtual Gate Test Series: Operating System - Fork-Join Concurrency Structure
Consider the code fragment: count = 3; S1; Fork L1; L1: S3; S2; goto L3; S4; Fork L2; L2: S6; goto L3; S5; L3: join count S7 Which one of the following represents correct precedence graph of the above code fragment? the answer is given but I’m getting where am I wrong?

answered Jul 24 in Operating System by shivam001 (271 points) | 102 views

0 votes

1 answer

29

Galvin Edition 9 Exercise 6 Question 2 (Page No. 306)
Explain the difference between preemptive and nonpreemptive scheduling.

answered Jul 24 in Operating System by Dhiraj Singh (21 points) | 11 views

+2 votes

4 answers

30

UGCNET-June-2019-II-45
Consider three CPU intensive processes, which require $10$, $20$ and $30$ units of time 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. $4$ $2$ $3$ $1$

answered Jul 24 in Operating System by Satbir Boss (17.2k points) | 38 views

+1 vote

2 answers

31

UGCNET-June-2019-II-44
Which of the following are NOT shared by the threads of the same process? Stack Registers Address space Message queue a and d b and c a and b a, b and c

answered Jul 24 in Operating System by Nishi Agarwal (73 points) | 46 views

0 votes

1 answer

32

Galvin Edition 9 Exercise 4 Question 12 (Page No. 192)
Using Amdahl’s Law, calculate the speedup gain of an application that has a 60 percent parallel component for (a) two processing cores and (b) four processing cores.

answered Jul 23 in Operating System by Ram Swaroop Active (3.9k points) | 37 views

+31 votes

4 answers

33

GATE1998-7-b
In a computer system where the best-fit' algorithm is used for allocating jobs' to memory partitions', the following situation was encountered:$\begin{array}{|l|l|} \hline \textbf{Partitions size in $KB$} & \textbf{$4K \ 8K \ 20K \ 2K$} \\\hline \textbf{Job sizes in $ ... $} \\\hline \end{array}$When will the $20K$ job complete?

answered Jul 22 in Operating System by ayushsomani (215 points) | 3k views

+1 vote

1 answer

34

Doubt in Reader-Writer Problem's Solution
Why in reader section we are locking(I highlighted the locking) read_count-- and if section? If we don't use locking what problems might arise? I know that we should use locking whenever we access shared variable but in this particular case I don't see any problem if we don't use locking(highlighted). Please explain what I am missing

answered Jul 21 in Operating System by !KARAN Active (1.8k points) | 68 views

+2 votes

1 answer

35

UGCNET-June-2019-II-42
Match List-I with List-II: ... below: a-i; b-ii; c-iii; d-iv a-iii; b-i; c-iv; d-ii a-ii; b-i; c-iv; d-iii a-ii; b-iv; c-iii; d-i

answered Jul 20 in Operating System by Satbir Boss (17.2k points) | 42 views

+1 vote

2 answers

36

UGCNET-June-2019-II-43
Consider that a process has been allocated $3$ frames and has a sequence of page referencing as $1, 2, 1, 3, 7, 4, 5, 6, 3, 1$. What shall be the difference in page faults for the above string using the algorithms of LRU and optimal page replacement for referencing the string? $2$ $0$ $1$ $3$

answered Jul 19 in Operating System by Satbir Boss (17.2k points) | 39 views

+1 vote

2 answers

37

UGCNET-June-2019-II-48
A computer has six tape drives with $n$ processes competing for them. Each process may need two drives. What is the maximum value of $n$ for the system to be deadlock free? $5$ $4$ $3$ $6$

answered Jul 19 in Operating System by Satbir Boss (17.2k points) | 32 views

+7 votes

4 answers

38

GATE2019-33
Assume that in a certain computer, the virtual addresses are $64$ bits long and the physical addresses are $48$ bits long. The memory is word addressible. The page size is $8$ kB and the word size is $4$ bytes. The Translation Look-aside Buffer (TLB) in the address translation path has $128$ ... any TLB miss? $16 \times 2^{10}$ $256 \times 2^{10}$ $4 \times 2^{20}$ $8 \times 2^{20}$

answered Jul 19 in Operating System by manikantsharma (315 points) | 2.4k views

+3 votes

5 answers

39

GATE2019-39
Consider the following snapshot of a system running $n$ concurrent processes. Process $i$ is holding $X_i$ instances of a resource $R$, $1 \leq i \leq n$. Assume that all instances of $R$ are currently in use. Further, for all $i$, process $i$ can place a request for at most $Y_i$ additional ... $\text{Min}(X_p,X_q) \leq \text{Max} \{Y_k \mid 1 \leq k \leq n, k \neq p, k \neq q\}$

answered Jul 19 in Operating System by manikantsharma (315 points) | 1.8k views

+3 votes

4 answers

40

GATE2019-23
Consider three concurrent processes $P1$, $P2$ and $P3$ as shown below, which access a shared variable $D$ that has been initialized to $100$ ... maximum possible values of $D$ after the three processes have completed execution are $X$ and $Y$ respectively, then the value of $Y-X$ is ____

answered Jul 19 in Operating System by manikantsharma (315 points) | 3.2k views

tags	tag:apple
author	user:martin
title	title:apple
content	content:apple
exclude	-tag:apple
force match	+apple
views	views:100
score	score:10
answers	answers:2
is accepted	isaccepted:true
is closed	isclosed:true

Recent questions and answers in Operating System

Recent Posts

Recent Blog Comments