Memory consists of a large array of words or bytes, each with its own address. The CPU fetches instructions from memory according to the value of the program counter. These instructions may cause additional loading from and storing to specific memory addresses. Memory unit sees only a stream of memory addresses. It does not know […]

When a detection algorithm determines that a deadlock exists, several alternatives exist. One possibility is to inform the operator that a deadlock has occurred, and to let the operator deal with the deadlock manually. The other possibility is to let the system recover from the deadlock automatically. There are two options for breaking a deadlock. […]

1. Let Work and Finish be vectors of length m and n, respectively. Initialize: Work = Available Finish [i] = false for i = 0, 1, …,n- 1. 2. Find and i such that both: (a) Finish [i] = false (b) Needi≤Work If no such i exists, go to step 4. 3. Work = Work […]

This algorithm can be used in banking system to ensure that the bank never allocates all its available cash such that it can no longer satisfy the needs of all its customer. This algorithm is applicable to a system with multiple instances of each resource type. When a new process enter in to the system […]

In this graph a new type of edge has been introduced is known as claim edge. Claim edge Pi→Rj indicates that process Pj may request resource Rj; represented by a dashed line.Claim edge converts to request edge when a process requests a resource.Request edge converted to an assignment edge when the resource is allocated to […]

A binary semaphore is a semaphore with an integer value which can range between 0 and 1. Let ‘S’ be a counting semaphore. To implement the binary semaphore we need following the structure of data. Binary Semaphores S1, S2; int C; Initially S1 = 1, S2 = 0 and the value of C is set […]

The problem of deadlock can deal with the following 3 ways. We can use a protocol to prevent or avoid deadlock ensuring that the system will never enter to a deadlock state.  We can allow the system to enter a deadlock state, detect it and recover. We can ignore the problem all together. To ensure […]