critical section

Question

Answer 1

The answer is clearly option C).U can also refer to Galvin regarding the requirements of a solution to a critical section problem which are mutual exlusion , progress and bounded waiting.

Also we can say that atomic operation is not necessary because there exist solution to critical section problem which involves 2 and processes and we know pre emption is allowed between any set of concurrent processes and hence this means atomicity is not followed in that case.Atomicity means either all instructions to be executed or none.

In fact this is our default assumption that given any set of concurrent processes we can take preemption of any process at any instant to check whether the mutual exclusion , progress and bounded waiting are satisfied.So unless and until we are given the process is "Atomic" we can take preemption of that process.In that case atomicity is not followed.

Hence C) option is false.

Comments

a particular instruction should be executed atomically means isolation.....here atomicity means that suppose if 2 processes are taking part then either both should execute "fully" or none..
and obviously we cant go for such thing else how we will check mutual exclusion etc...we need to preempt a process in between to check such properties...so we dont go for atomicity;;

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Yes we dont go for atomicity unless and until it is mentioned in the question that a process is atomic.In that case , u cannot preempt

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There may be a case which invloves an operation can be divided into smaller suboperations and it may happen that preemption may be taken in between those suboperations.

Answer 2

mutual exclusion,progress  are the primary requirements

bounded waiting and portability are the secondary requirements

Comments

if we have more than one process inside the critical section than how we will solve the issue?
even in petersons method we allow one process at a time..

thats why m saying atomic operation is a must inside critical section...bounded waiting is secondary requirement;;

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yes option c i misunderstood atomicity with single operation inside critical section but it means either all should be executed or none..thanks;;

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Yes boss. You confused me.