Bilal Ahmed Khan slides se sirf mcqs aye te, baki paper out of slides ta, kio book consult kr lo, jo bi recommended ho lms pe,
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CS701 - Current Mid Term Papers Dated: 04-07-2015 time 07:30
CS710 Current Mid Term Papers Dated:04-07-2015 time 07:30
XftXb Khxlid
CS710 - 7:30am
10 MCQs thay - Baki qstn
Wearable & mobile computing difference
Windows APIs
stack of software components in Symbian
Device-independent views & Platform-independent controllers
Layered Architecture of Mobile Ad Hoc Networks in pervasive environment
Development phase of Symbian application
CS710 - 7:30am
10 MCQs thay - Baki qstn
Wearable & mobile computing difference
Windows APIs
stack of software components in Symbian
Device-independent views & Platform-independent controllers
Layered Architecture of Mobile Ad Hoc Networks in pervasive environment
Development phase of Symbian application
MS150200363
10 MCQs they
some are from past papers
3 questions
are of 5 marks
4 are of 10
marks
· Difference B/W
wearable and mobile computing(10)
· Windows 7OS
overview(5)
· Level of runtime
infrastructure for Disconnect able mobile apps (5)
· JNI and its
function(10)
· OS layer
functions in Symbian
· Kernel Functions
in Symbian
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CS704 - Computer Organization and Design The Hardware Software Interface 3rd Edition David A. Patterson and John L. Hennessy and its solution manual
Computer Organization and Design
The Hardware Software Interface
3rd Edition
David A. Patterson and John L. Hennessy
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OR Download Click here
Computer Organization and Design
The Hardware Software Interface
3rd Ed
2004 Solutions
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CS704 Solved Mid Term Exam Papers (File Size 2 MB only)
CS704 - Advanced Computer Architecture II Solved Mid Term Exam Papers by Muhammad Sadaqat Ali
Thanks to Allah Almighty whose give me ability to done this.
Dedicated to All Students of MSCS in the name of My Great Brother
Mr. Muhammad Bilal Ali
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CS701 COMPLETELY SOLVED PAST MID TERM PAPERS (FILE SIZE 3 MB ONLY NOW)
CS701 Solved Mid Term Exam Papers by Muhammad Sadaqat Ali
Thanks to Allah Almighty whose give me ability to done this.
Dedicated to All Students of MSCS in the name of My Great Brother
Mr. Muhammad Bilal Ali
CS704 - Advanced Computer Architecture II Solved Mid Term Exam Papers by Muhammad Sadaqat Ali
CS704 - Advanced Computer Architecture II Solved Mid Term Exam Papers by Muhammad Sadaqat Ali
Thanks to Allah Almighty whose give me ability to done this.
Dedicated to All Students of MSCS in the name of My Great Brother
Mr. Muhammad Bilal Ali
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CS701 - Theory of Computation Solved Mid Term Exam Papers by Muhammad Sadaqat Ali
CS701 - Theory of Computation Solved Mid Term Exam Papers by Muhammad Sadaqat Ali
Thanks to Allah Almighty whose give me ability to done this.
Dedicated to All Students of MSCS in the name of My Great Brother
Mr. Muhammad Bilal Ali
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Software Engineering by Ian Somerville
https://www.facebook.com/mscsinterface
Software Engineering by Ian Somerville
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CS703 – ADVANCED OPERATING SYSTEMS MS (CS), SPRING 2015 ASSIGNMENT NO. 2 SOLVED BY Muhammad Sadaqat Ali Due Date: 11th June, 2015
CS703 –
ADVANCED OPERATING SYSTEMS
MS (CS),
SPRING 2015
ASSIGNMENT
NO. 2 Due
Date: 11th June, 2015
SOLVED BY
Muhammad Sadaqat Ali
Question 1
Reader/writer locks are specialized locks used to solve the
readers/writers problem. Consider the
following pseudo-code implementation of reader-writer locks
which is a variant of the
readers/writers solution discussed in lectures but
implemented via semaphores. Note that readers
must call the function AcquireReadLock before reading the
data while writers must call
AcquireWriteLock before modifying or updating the data. Once
data access has been completed, the
locks must be released by calling the ReleaseReadLock() and
ReleaseWriteLock() functions
respectively :
Class ReaderWriterLock {
Semaphore mutex = 1;
// declaration of a semaphore
OkToRead = 0; // a flag to check it is OK to read the
database
OkToWrite = 0; // a
flag to check it it is OK to write the database
int ACTIVEREADERS=0;// number of readers holding the read
lock and accessing the database
WAITINGREADERS=0; // number of readers waiting to acquire
read lock
ACTIVEWRITERS=0; // number of writers that have acquired
write lock
//
(practically this will always be 1)
WAITINGWRITERS=0; // number of writers that are waiting for
write lock
void AcquireReadLock()
{
P(mutex); // remember that P operation on a semaphore means
decrementing its value
if ((ACTIVEWRITERS == 0)
{
V(OkToRead); //
remember that V operation on a semaphore means incrementing its value
ACTIVEREADERS++;
}
else
{
WAITINGREADERS++;
}
V(mutex);
P(OkToRead);
}
void ReleaseReadLock()
{
P(mutex);
ACTIVEREADERS--;
if ((ACTIVEREADERS
== 0) && (WAITINGWRITERS > 0))
{
V(OkToWrite);
ACTIVEWRITERS++;
WAITINGWRITERS--;
}
V(mutex);
}
void AcquireWriteLock()
{
P(mutex);
if (ACTIVEWRITERS +
ACTIVEREADERS == 0)
{
V(OkToWrite);
ACTIVEWRITERS++;
}
else
{
WAITINGWRITERS++;
}
V(mutex);
P(OkToWrite);
}
void ReleaseWriteLock()
{
P(mutex);
ACTIVEWRITERS--;
if (WAITINGWRITERS
> 0)
{
V(OkToWrite);
ACTIVEWRITERS++;
WAITINGWRITERS--;
}
else
{
while
(WAITINGREADERS > 0)
{
V(OkToRead);
ACTIVEREADERS++;
WAITINGREADERS--;
}
}
V(mutex);
}
} // end of class
a)
Briefly explain why AcquireReadLock() and AcquireWriteLock()
functions perform P and V
operations on the mutex semaphore in the above code?
Solution:
A semaphore is a protected variable whose value can be
accessed and altered only by the operations P and V.
When semaphore operations has started, no other process can
access the semaphore until operation has completed. Mutual exclusion on the
semaphore is enforced within P and V.
P semaphore function signals that the task requires a
resource and if not available waits for it.
V semaphore function signals which the task passes to the OS
that the resource is now free for the other users.
In the above code, P and V semaphore functions used with
mutex property.
For AcquireReadLock() :
P and V Semaphore functions with mutex property ─ Wait for
starting Critical Section
P(mutex); // remember that P operation on a semaphore means
decrementing its value
The codes will
execute only when mutex not less than 0. it keep wait until the resource become
available for further processing.
P and V Semaphore functions with mutex property ─ running
end exiting Critical Section
V(OkToRead); // remember that V operation on a semaphore
means incrementing its value
if OkToRead not equal
to 0 or not less than 0. No other process is executing at present. Now reader
can access DB.
V(mutex);
mutex not equal to 0 or not less than 0. No processor
(reader) process executing at present.
P(OkToRead);
The following codes will execute only when OkToRead not less
than 0. Wait for Reader.
For AcquireWriteLock():
P(mutex);
The codes will execute only when mutex not less than 0. it
keep wait until the resource become available for further processing.
V(OkToWrite);
if OkToWrite not equal to 0 or not less than 0. No other process
is executing at present. Now writer can access DB.
V(mutex);
mutex not equal to 0 or not less than 0. No processor
(writer) process executing at present.
P(OkToWrite);
The following codes will execute only when OkToWrite not
less than 0. Wait for Writer.
(b)
Briefly explain whether readers or writers could be starved
due to this implementation?
Solution:
In this code, Writer could be starved as the priority is
given to Reader.
In the function, void ReleaseWriteLock(), implementation for
WaitingReader gives access to ActiveReader and if waitingwriter available, only
access given to ActiveWriter and then instead of accessing DB to waiting writer
access is given to Reader.
Thus, Writer could be starved.
c) Suggest a mechanism through which a no starvation policy
could be implemented. In other
words, suggest in words, how would you modify the code such
that a starvation-free
implementation results.
Solution:
To get starvation free implementation results, we can use
any scheduling algorithm as the task of the scheduler is to find a conflict
free matching based on input requests.
Four major scheduling algorithm are:
First Come
First Serve FCFS Scheduling
Shortest Job
First Scheduling
Priority
Scheduling
Round Robin
Scheduling
Multilevel
Queue Scheduling
All these algorithm have their own advantages and
disadvantages.
Question 2
Review the Readers/Writers problem discussed in lecture 12,
write the code for Reader() and
Writer() functions, when readers are given priority over
writers, keeping the problem constraints in
mind.
Solution:
Reader () {
lock.Acquire();
while (AW > 0) {
WR++;
okToRead.wait(&lock);
WR--;
}
AR++;
lock.Release();
Access DB
lock.Acquire();
AR--;
If (WR > 0) {
okToRead.Broadcast(&lock);
} else if (AR == 0
& WW > 0) {
okToWrite.Signal(&lock);
}
lock.Release();
}
Writer () {
lock.Acquire();
while ((AR + WR + AW)
> 0) {
WW++;
okToWrite.Wait(&lock);
WW--;
}
AW++;
lock.Release();
Access DB
lock.Acquire();
AW--;
If (WR > 0)
okToRead.Broadcast(&lock);
else if (WW > 0)
okToWrite.Signal(&lock)
lock.Release();
}
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