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How to understand the operating system banker algorithm implemented in C language, aiming at this problem, this article introduces the corresponding analysis and solution in detail, hoping to help more partners who want to solve this problem to find a more simple and feasible method.

First, the background of the topic

This course design requires the completion of a resource management system and a mastery of the working principle of using banker algorithms to manage resource allocation in the system. In-depth understanding of the importance of rational resource allocation in multiprogramming systems, and deepen the understanding of deadlock concepts. The banker algorithm is simulated to allocate the system resources to prevent the occurrence of deadlock. This topic is certainly impossible to achieve the resource management of the actual operating system, but through the processing of simulated resource data to detect the role of banker algorithms in preventing deadlocks.

II. Scheme argumentation

The banker algorithm is simulated to allocate the system resources to prevent the occurrence of deadlock. This topic is certainly impossible to achieve the resource management of the actual operating system, but through the processing of simulated resource data to detect the role of banker algorithms in preventing deadlocks. First check the validity of the request made by the user, that is, check whether the request is no more than needed and whether it is not more than available. If the request is legal, a trial allocation is carried out. Finally, the security check algorithm is used to check the security of the state after the trial allocation. If it is safe, it will be allocated, otherwise, it will not be allocated, the original state will be restored and the application will be rejected.

Third, the experimental environment

Windows operating system

VS 2013

C language

Fourth, design ideas and experimental steps 4.1 Design ideas

First check the validity of the request made by the user, that is, check whether the request is no more than needed and whether it is not more than available. If the request is legal, a trial allocation is carried out. Finally, the security check algorithm is used to check the security of the state after the trial allocation. If it is safe, it will be allocated, otherwise, it will not be allocated, the original state will be restored and the application will be rejected.

4.2 data structure in Banker algorithm

Available resource vector Available. This is an array of m elements, each of which represents the number of available resources of a class, and its initial value is the number of all available resources of this class configured in the system, and its value varies dynamically with the allocation and recovery of such resources. If Available [j] = K, it means that there are K Rj class resources in the system.

Maximum demand matrix Max. This is a matrix that defines the maximum requirements for class resources for each process in the system. If Max [I _ I _ j] = K, the maximum number of Rj class resources required by process I is K.

Allocation matrix Allocation. This is also a matrix that defines the number of resources currently allocated to each process for each type of resource in the system. If Allocation [iQuery j] = K, it means that the number of Rj class resources currently allocated to process I is K.

Demand matrix Need. This is also a matrix that represents the number of resources required for each process. If Need [iQuery j] = K, it means that process I still needs K resources of Rj class to complete the task.

That is:

Int M; / / Total processes

Int N; / / Resource type

Int ALL_ resources [W]; / / Total number of various resources

Int Max [W] [R]; / / maximum demand matrix, M processes have maximum resource requirements for N-type resources

Int Available [R]; / / available resource vector

Int Allocation [W] [R]; / / allocation matrix, each process M has obtained the number of resources for category N resources

Int Need [W] [R]; / M processes also need the amount of resources of category N resources

Int Request [R]; / / the number of requested resources for the process

The relationships between the above three matrices are as follows:

4.3Banker algorithm bank ()

Let Requesti be the request vector of the process Pi. If Requesti [j] = K, it means that the process Pi needs K resources of type Rj. After the request is made, the system checks as follows:

(1) check whether the number of applications is not greater than the demand. If Request I [j]

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