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Questions by Debashish Deka
User Debashish Deka
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User Debashish Deka
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0
votes
0
answers
1
Find correct statements
Find correct statements: The read system call to fetch data from a file always blocks the invoking process. During filesystem operations, if the file system implementation ensures that changes to data blocks of a file are flushed to disk before changes to ... interrupts on its CPU core for the duration that the spinlock is held, in both single core and multi core systems.
asked
Jan 13
in
Operating System

37
views
operatingsystem
+1
vote
1
answer
2
TLB hit ration and memory lookup time
Consider a system where TLB lookup time is $25$ ns and memory access time is $200$ ns, respectively. Assuming a virtual address space of $2$ KB, page size of $32$ bytes, and a PTE size of $2$ bytes, what is the minimum TLB hit ratio that results in an average v2p (virtual to physical) translation latency of $185$ ns?
asked
Jan 13
in
Operating System

38
views
tlb
hitratio
0
votes
0
answers
3
process state in operating system
Consider a process P1 that is executing on a Linuxlike OS on a single core system. When P1 is executing, a disk interrupt occurs, causing P1 to go to kernel mode to service that interrupt. The interrupt delivers all the disk blocks that unblock a ... user mode of P1. At this point in time, what are the states (ready/running/blocked) of processes P1 and P2 ?
asked
Jan 13
in
Operating System

35
views
operatingsystem
process
0
votes
0
answers
4
fork and exec
what is the output of the following program? int ret = fork(); if(ret == 0) { exec(some_binary); // this call fails printf("child "); }else { wait(); printf("parent\n"); } Runtime Error child parent child parent
asked
Jan 13
in
Operating System

32
views
fork
operatingsystem
0
votes
0
answers
5
SpinLock in the kernel Mode
Consider a process in kernel mode that acquires a spinlock. For correct operation, it must disable interrupts on its CPU core for the duration that the spinlock is held, in both single and multicore systems.[True / False]
asked
Sep 15, 2018
in
Operating System

12
views
operatingsystem
0
votes
0
answers
6
Read system call
The read system call to fetch data from a file always blocks the invoking process.[True / False] [blocking means context switching to another process]
asked
Sep 15, 2018
in
Operating System

5
views
operatingsystem
0
votes
0
answers
7
Open file table
When a process opens a file that is already being read by another process, the file descriptors in both process will point to the same open file table entry.[True / False]. (open file table ?)
asked
Sep 15, 2018
in
Operating System

13
views
operatingsystem
filesystem
0
votes
1
answer
8
Fork system call,open file table
The fork system call creates new entries in the open file table for the newly created child process. [True / False] [ what is open file table ? ]
asked
Sep 15, 2018
in
Operating System

80
views
operatingsystem
fork
0
votes
0
answers
9
Privileged modes
The four privileged modes (Ring 0 to Ring 3 as provided by x86) are the minimum levels of execution modes required for an operating system to operate correctly
asked
Sep 13, 2018
in
Operating System

9
views
operatingsystem
nongate
0
votes
0
answers
10
System Call
Illustrate the sequence of events/steps for invocation and execution of a system call. Starting from the user level call and back.
asked
Sep 13, 2018
in
Operating System

7
views
operatingsystem
nongate
+1
vote
1
answer
11
Estimate the average time to access data from memory
Estimate the average time to access data from memory with the following information, page fault service time = $2$ ms, memory access time = $200$ ns, $10$ page faults for every $10^6$accesses, TLB hit rate = $50\%$, ... to execute the page fault handler and update the v2p mapping (via possible evictions of other pages, reading from disk etc.)
asked
Sep 13, 2018
in
Operating System

25
views
operatingsystem
nongate
0
votes
0
answers
12
Interrupt handling
Give an example each for a hardware interrupt, an explicit software interrupt, and an implicit software interrupt, and discuss the possible operations as part of the interrupt handler.
asked
Sep 13, 2018
in
Operating System

15
views
interrupts
operatingsystem
nongate
0
votes
0
answers
13
System call
A system call operates in a process context. Give an example and explain this statement.
asked
Sep 13, 2018
in
Operating System

10
views
operatingsystem
nongate
0
votes
1
answer
14
Virtual address space
A onetoone mapping of the entire physical address space to a process's virtual address space is a correct address translation solution. True/False. Explain.
asked
Sep 13, 2018
in
Operating System

55
views
operatingsystem
memorymanagement
nongate
0
votes
1
answer
15
Page Table
A page table based translation will always consume less memory to store translation metadata, than a segmentation based solution. True/False. Explain.
asked
Sep 13, 2018
in
Operating System

48
views
memorymanagement
pagetable
operatingsystem
nongate
0
votes
0
answers
16
Context Switch : kernel stackuser stack
Consider the following events that happen during a context switch of process $P$ to (user mode of) process $Q$, triggered by a timer interrupt that occurred when $P$ was executing in a Unix like operating system. Arrange the events in the chronological ... the kernel address space of $Q$ to the user address space of $Q$ (E) The OS scheduler code is invoked.
asked
Aug 29, 2018
in
Computer Networks

65
views
operatingsystem
iitb
0
votes
0
answers
17
Wireless network media access protocol : RTS CTS and its problems
Four wireless nodes are placed on a straight line (see Figure $1$). Let $D(i, j)$ denote the distance between nodes $i$ and $j$. Each node has a circular communication range of $r = 1.5R$. This means that a ... $a$. Explain why this is true. Make any reasonable assumptions and state them clearly. (A rough explanation will do.)
asked
Aug 29, 2018
in
Computer Networks

42
views
computernetworks
iitb
0
votes
0
answers
18
Medium access in shared media and thoughtput
Consider a scenario in which $\textbf{n}$ hosts share the same medium. The medium has bandwidth (max. data rate) $c$. Time is divided into slots of duration $T$ ... varying $p$)? Interpret your results. (c) What is the limit of maximum throughput as $n \rightarrow \infty$ ? Interpret your results.
asked
Aug 29, 2018
in
Computer Networks

23
views
computernetworks
iitb
0
votes
0
answers
19
Probability and random variable
Consider the sets $A_1, A_2, A_3 \dots A_m$ each a subset of size $k$ of $\{1,2,3, \dots , n\}$. If in a 2colouring of $\{1,2,3, \dots , n\}$ no set $A_i$ is monochromatic, then show that $ m < 2^{k1}$.
asked
Apr 28, 2018
in
Set Theory & Algebra

71
views
probability
randomvariable
combinatoricsiitb
0
votes
1
answer
20
Set theory
Consider the sets $A_1, A_2, A_3 \dots A_m$. Prove that the number of distinct sets of the form $A_i \oplus A_j$ is at least $m$.
asked
Apr 28, 2018
in
Set Theory & Algebra

57
views
settheory
combinatoricsiitb
0
votes
0
answers
21
Set theory and Induction
Consider the set of all subsets of a set S. A chain is a collection of subsets $P_1 \subset P_2 \subset P_3 \subset P_4 \dots \subset P_k$. A symmetric chain is one which starts at a set of size $i$ and ends at a set of size $n  i$. Prove that the poset has a decomposition into symmetric chains.
asked
Apr 28, 2018
in
Set Theory & Algebra

38
views
settheory
combinatoricsiitb
+2
votes
4
answers
22
Counting
Show that, in a grid, the number of paths from $(0,0)$ to $(n,n)$ which does not cross ( it could touch ) the line $x = y$ is \begin{align*} \frac{1}{1+n}\binom{2\cdot n}{n} = \binom{2\cdot n}{n}  \binom{2\cdot n}{n1} \end{align*} After that, show the number of balanced paranthesis strings of length $2n$ is same as the above result.
asked
Apr 27, 2018
in
Set Theory & Algebra

107
views
counting
combinatoricsiitb
0
votes
0
answers
23
Probability and set theory
Consider sets $A_1,A_2,A_3 \text{ to } A_m \text{ where }A_i \subseteq [n] \text{ and } [n] = \{1,2,3, \dots n \}$ such that there are no three distinct sets in the collection with the property $A_i \subset A_j \subset A_k.$ For even $n$, prove that \begin{align*} m ... bound on $m$ : \begin{align*} m \leq \binom{n}{\frac{n}{2}} + \binom{n}{\frac{n}{2}  1} \end{align*}
asked
Apr 27, 2018
in
Set Theory & Algebra

34
views
probability
settheory
combinatoricsiitb
0
votes
1
answer
24
Induction
Prove that the number of edges in a graph with exactly one triangle is at most \begin{align*} \frac{\left( n  1 \right )^2}{4} + 2 \end{align*}
asked
Apr 27, 2018
in
Graph Theory

61
views
induction
graphtheory
combinatoricsiitb
0
votes
0
answers
25
Probability
Prove for a positive integer valued random variable, $X$ , and for positive integers $a < b$ \begin{align*} &P(X \geq b) \leq \left [ \left ( \frac{E(X)}{b} \right )  P(a \leq X < b)\cdot \left ( \frac{a}{b} \right ) \right ] \\ \end{align*}
asked
Apr 27, 2018
in
Probability

33
views
probability
combinatoricsiitb
+1
vote
1
answer
26
Set system and linear algebra
We have $m$ sets $A_1,A_2,A_3 \text{ to } A_m$. All $A_i \subseteq [n]$ where $ [n] = \{1,2,3, \dots n \}.$ Given that $A_i = \text{odd number}$ and $A_i \cap A_j = \text{even number }\forall i \neq j$. Show that $m \leq n$.
asked
Apr 16, 2018
in
Set Theory & Algebra

390
views
sets
linearalgebra
combinatoricsiitb
+3
votes
0
answers
27
Conditional probability
A student $Y$ lives in a place $X$. In $X$ a day can be cloudy with probability $\bf0.02$ uniformly each day. $Y$'s friends may come to his house with probability $\bf0.2$ uniformly in each day irrespective of weather condition. These two events are independent. $Y$ can ... on a particular day ?
asked
Dec 25, 2017
in
Probability

153
views
conditionalprobability
+2
votes
0
answers
28
Graph Degree sequence : Bondy and Murty : $1.1.16$
Let $d = (d_1,d_2,\dots, d_n)$ be a nonincreasing sequence of nonnegative integers, that is, $d_1 \geq d_2 \geq · · · \geq d_n \geq 0$. Show that: there is a loopless graph with degree sequence d if and only if $\sum_{i=1}^{n}d_i$ is even and $d_1 \leq \sum_{i=2}^{n}d_i$
asked
Jul 5, 2017
in
Graph Theory

153
views
graphtheory
nongate
proof
+1
vote
0
answers
29
Graph Theory : BondyMurty $1.1.20$
Let $S$ be a set of $n$ points in the plane, the distance between any two of which is at least one. Show that there are at most $3n$ pairs of points of S at distance exactly one. Can this be done with a unit circle and we can place at max. $6$ points on the perimeter and doing the same for other points as well ? i.e. we can get $6n/2 = 3n$ pairs at max. ?
asked
Jul 5, 2017
in
Graph Theory

103
views
graphtheory
nongate
proof
+2
votes
0
answers
30
Graphic Sequence condition
A sequence $d = (d_1,d_2,\dots , d_n)$ is graphic if there is a simple graph with degree sequence $d$ If $d = (d_1,d_2,d_3, \dots d_n)$ is graphic and $d_1 \geq d_2 \geq d_3 \geq \dots \geq d_n$ , then show that $\sum_{i=1}^{n}d_i$ is even and $\sum_{i=1}^{k}d_i \leq \left [ k(k1) + \sum_{i=k+1}^{n} \min\{k,d_i\} \right ] \quad ,1 \leq k \leq n$.
asked
Jul 4, 2017
in
Graph Theory

119
views
nongate
graphtheory
proof
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