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# Assignment No. 03 Semester: Fall 2014 CS604 –Operating System Total Marks: 15 Due Date: 16/2/2015

• Your assignment must be in .doc format. (Any other formats like scan images, PDF, Zip, rar, bmp,etc will not be accepted).
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Assignment

Question 1:   (5 Marks)

Consider the following snapshot of a system:

 Allocation Max Available A B C D A B C D A B C D P0 1 1 1 2 3 4 2 2 1 2 3 4 P1 1 0 2 2 1 3 4 14 P2 1 4 5 6 2 7 5 8 P3 2 5 4 2 3 5 7 9 P4 1 5 2 7 1 6 3 9

 Need A B C D

Answer the following questions using the banker’s algorithm:

(a)   What is the content of the matrix Need?                                             5

(b)   Is the system in a safe state? If yes identify the safe sequence. Show the step by step execution by updating the data structure if necessary.                                                            10

NOTE:Do not put any query on MDB about this assignment, if you have any query then emailatcs604@vu.edu.pk.

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### Replies to This Discussion

this assignment is starving due to bad algorithm.

starvation problem

all students are here in deadlock, & busy waiting state.

@Zakki

So, here we should use Banker's algorithm to break the dead lock.

So start allocating the resources now.

Mera matlab he koi to discussion shuru kro na yar.

my safe sequence answer is : <P4,P0,P1,P2,P3>

is this correct?

a)      Content of the matrix Nedd:

 Need A B C D 2 3 1 0 0 3 2 12 1 3 0 2 1 0 3 7 0 1 1 2

any one tel me how we find safe sequence muje to samaj nahi a rahi he just thora sa hint hi de den please

With the banker's algorithm you know the total number of resources available, and the maximum number of resources that each process may request. Being conservative, you're a banker after all, you assume that any process will request its maximum resources before finishing.

correct !

P4--P0--P1--P2--P3  ...is it correct ?

This is not correct Sequence..........

Correct sequence is  P4,P0,P2,P3,P1

---------------------

the longest deadlock in the history.

 Allocation Max Available A B C D A B C D A B C D P0 1 1 1 2 3 4 2 2 1 2 3 4 P1 1 0 2 2 1 3 4 14 2 7 5 11 P2 1 4 5 6 2 7 5 8 3 8 6 13 P3 2 5 4 2 3 5 7 9 4 12 10 18 P4 1 5 2 7 1 6 3 9 6 17 14 20

 Safe Sequence is……….

?

where is complete sol?

1

2

3

4

5

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