test series os

Question

Suppose 10 processes P₁ to P₁₀ share 7 identical resource units which can be reserved and release 1 at are time the maximum resource requirement of a processs P _i is S_P where S_P is greater then 0. The maximum value of that ensures deadlock does not occurs is ________ .     

Comments

61 ?

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answer is 16 Prabhanjan_1

Answer 1

To prevent deadlock...we give 1 less than the maximum requirement to each process. Then add one more resource so that at least one process can complete and we don't have a deadlock situation. 

This question is very poorly defined. It is based on a previous year Gate question.

So we give S_p-1 to each of the 10 processes and add one more. We get 10S_p-10+1. This must be equal to 7( no of resources we have) if we want to avoid deadlock. 

So 10S_p= 16

Answer 2

Each process needs 7 resource units.total of 70 resources.

p1

p2

p3

p4

p5

p6

p7

p8

p9

p10

7

7

7

7

7

7

7

7

7

7

Each process needs maximum seven units of resources.to prevent deadlock these are maximum resources.

minimum no of resources are=(6*10)+1.  //for all 10 process allocate 6 units of resources all are waiting on each other for one more resource to excution.

so total of 61 resources are needed to prevent deadlock.