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Higher Study | Operating Systems | Deadlock

An operating system uses the Banker’s algorithm for deadlock avoidance when managing the allocation of three resource types X, Y, and Z to three processes P0, P1, and P2. The table given below presents the current system state. Here, the Allocation matrix shows the current number of resources of each type allocated to each process and the Max matrix shows the maximum number of resources of each type required by each process during its execution.   Allocation Max   X Y Z X Y Z P0 0 0 1 8 4 3 P1 3 2 0 6 2 0 P2 2 1 1 3 3 3   There are 3 units of type X, 2 units of type Y and 2 units of type Z still available. The system is currently in a safe state. Consider the following independent requests for additional resources in the current state: REQ1: P0 requests 0 units of X, 0 units of Y and 2 units of Z REQ2: P1 requests 2 units of X, 0 units of Y and 0 units of Z Which one of the following is TRUE?
A system shares 9 tape drives. The current allocation and maximum requirement of tape drives for three processes are shown below: Process Current Allocation Maximum Requirement P1 3 7 P2 1 6 P3 3 5   Which of the following best describes current state of the system?
Consider the following implementation as a solution to the critical section problem for two processes P0 and P1 with id 0 and 1, respectively. int flag [2] = {0, 0}; int turn = 0 ; void lock (int id)  /*id = 0 or 1 */ { turn = id ^ 1; /*S1*/ flag [id] = 1; /*S2*/ /* '^' is the bitwise XOR* / while (flag [id ^ 1] ) && turn == (id ^ 1)) ; } void unlock (int id) { flag[id] = 0 ; } Which of the following statements are correct?
Which one of following statements is FALSE?
Which of the following conditions need to be held simultaneously for deadlock occurrences
Which of the following is NOT the method for handling deadlock?
Consider the following two-process synchronization solution. Process 0 - - - - - - - - Entry: loop while (turn == 1);  (critical section) Exit: turn = 1; Process 1 - - - - - - - - Entry: loop while (turn == 0);  (critical section) Exit: turn = 0;   The shared variable turn is initialized to zero. Which one of the following is TRUE?
A multithreaded program P executes with x number of threads used y number of locks for ensuring mutual exclusion while operating on shared memory locations. All locks in the program are non-re-entrant. i.e. if a thread holds a lock l, then it cannot re-acquire lock l without releasing it. If a thread is unable to acquire a lock, it blocks until the lock becomes available. The minimum value of x and the minimum value of y together for which execution of p can result in a deadlock are:
Consider a system having m resources of the same type. These resources are shared by 3 processes A, B, C, which have peak time demands of 3, 4, 6 respectively. The minimum value of m that ensures that deadlock will never occur is
Consider the following snapshot of a system running n concurrent processes. Process i is holding Xi instances of a resource R, 1 ≤ i ≤ n. Assume that all instances of R are currently in use. Further, for all i, process i can place a request for at most Yi additional instances of R while holding the Xi instances it already has. Of the n processes, there are exactly two processes p and q such that Yp = Yq = 0. Which one of the following conditions guarantees that no other process apart from p and q can complete execution?
Which of the following is not true with respect to deadlock prevention and deadlock avoidance schemes?
A system has 6 identical resources and N processes competing for them. Each process can request at most 2 resources. Which one of the following values of N could lead to a deadlock?
What is the minimum number of resources required to ensure that deadlock will never occur, if there are currently three processes P1, P2, and P3 running in a system whose maximum demand for the resources of the same type are 3, 4, and 5 respectively?
In a system, there are three types of resources and four processes that execute concurrently. At the outset, the processes have declared their maximum resource requirements using a matrix named Max as given below. For example, Max[ ] is the maximum number of instances of that would require. The number of instances of the resources allocated to the various processes at any given state is given by a matrix named Allocation. Consider a state of the system with the Allocation matrix as shown below, and in which 3 instances of E and 3 instances of F are the only resources available. Allocation   E F G P0 1 0 1 P1 1 1 2 P2 1 0 3 P3 2 0 0   Max   E F G P0 4 3 1 P1 2 1 4 P2 1 3 3 P3 5 4 1   From the perspective of deadlock avoidance, which one of the following is true?
What is a deadlock?
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