A dispatcher is an essential component of an operating system (OS) that manages and allocates system resources to different processes.

It acts as a bridge between the user and the system hardware, responsible for scheduling the execution of processes and managing the use of system resources, including CPU time, memory, and I/O devices.

The primary role of the dispatcher is to ensure that all the processes running on the system receive the necessary resources in a fair and efficient manner, minimizing the waiting time and maximizing the system throughput.

The dispatcher works closely with the process scheduler, which determines which process gets to use the CPU next.

When a new process is created or an existing process is interrupted or blocked, the dispatcher assigns it a priority level based on its importance and urgency.

It then determines which process should be scheduled next based on their priority levels and the current state of the system. This decision-making process is known as process scheduling, and it is essential for the efficient use of system resources.

Apart from process scheduling, the dispatcher is also responsible for managing the use of system resources in each process. It ensures that the process gets access to the required resources, such as memory and I/O devices while preventing resource contention or deadlock situations.

For example, it may use techniques such as resource locking and semaphores to prevent two processes from accessing the same resource simultaneously.

Another important role of the dispatcher is to manage the context switching between processes. When a process is blocked or interrupted, the dispatcher saves its current state, including the contents of the CPU registers and the program counter, into the process control block (PCB) and loads the state of the next process to be executed.

When the original process resumes execution, the dispatcher restores its saved state from the PCB, allowing it to continue from where it left off.

Final Thoughts 

The dispatcher plays a crucial role in managing the system resources and ensuring the efficient execution of processes. It performs process scheduling, manages resource allocation and usage, and handles context switching between processes.

Without the dispatcher, the operating system would not be able to manage multiple processes effectively, leading to poor system performance and resource contention issues.