Operating systems: Deadlock concept


If there are 6 processes and each requires 2 resources.Then what are the minimum number of resources to prevent deadlock?

A) 6
B) 7


Use the deadlock free condition i.e. R>=P(N-1)+1.Here R=? , P=no. of processes =6 and N= request =2. which gives R>=6(2-1)+1 ie. R>=7. Hence minimum number of resources to prevent deadlock is 7.


suppose To occur deadlock all process acquires 1 resources (less than 1 it required) so 6 process acquires 6 requires. so to avoid deadlock we need at least one resource which will full fill the need of one process.later that process executes and releases resources which will be acquired by other process.


Now it depends on conditions, 6 may be the minimum number, because if each process consumes one resource i.e., 6 resources and share the resources simultaneously then there will be no deadlock, but if the resource1 is required by process 2 and process 3 at same time then the answer 6 is not valid. So, thinking of worst case atleast 9 can also be the answer. But since minimum is asked 6 is the minimum number


p1=1| p2=1| p3=1| p4=1| p5=1| p6=1

+1 to any process so that it can complete its work and can forward the resources to other processes.
So minimum 7 resources are required.