Last Updated on May 8, 2024 by Abhishek Sharma
In computer science, particularly in the realm of operating systems, the terms dispatcher and scheduler are often used in the context of process management. While both are crucial components of an operating system that play roles in managing processes, they serve different functions and operate at different levels of the system. In this article, we will explore the definitions of dispatcher and scheduler, their respective roles, and the key differences between them.
What is Dispatcher?
The dispatcher is a component of the operating system responsible for the actual transfer of control from the scheduler to the selected process. It is essentially the mechanism that switches the CPU from one process to another, allowing the selected process to execute.
Functions of the Dispatcher
Below are some functions of the Dispatcher
- Context Switching: The dispatcher performs context switching, which involves saving the state of the currently running process (such as its register values, program counter, and other relevant information) and loading the state of the selected process into the CPU registers.
- Resource Allocation: It may also be responsible for allocating resources such as memory and I/O devices to the selected process, ensuring that the process has everything it needs to execute.
- Control Transfer: The dispatcher transfers control of the CPU to the selected process, allowing it to begin execution.
What are Scheduler?
The scheduler is another component of the operating system that is responsible for selecting the next process to run on the CPU. It determines the order in which processes are executed based on various scheduling algorithms and policies.
Functions of the Scheduler
Below are some functions of the Scheduler:
- Process Selection: The scheduler selects the next process to run on the CPU based on its scheduling algorithm and criteria such as priority, time quantum, and process state.
- Resource Management: It manages system resources such as CPU time, memory, and I/O devices to ensure efficient and fair allocation among processes.
- Scheduling Policies: The scheduler implements scheduling policies to optimize system performance, such as minimizing response time, maximizing throughput, or ensuring fairness among processes.
Difference Between Dispatcher and Scheduler
Difference Between Dispatcher and Scheduler are discussed below:
| Feature | Dispatcher | Scheduler |
|---|---|---|
| Function | Performs context switching and resource allocation. | Selects the next process to run based on scheduling policies. |
| Level of Operation | Operates at a lower level, managing process execution. | Operates at a higher level, making decisions about process selection. |
| Frequency of Execution | Executed every time a context switch occurs. | Executed periodically or in response to certain events. |
| Visibility to Users | Transparent to users, operates behind the scenes. | Can affect perceived performance by users. |
Conclusion
While both the dispatcher and scheduler are essential components of an operating system that contribute to the efficient management of processes, they serve different functions and operate at different levels of the system. The dispatcher is responsible for the actual transfer of control between processes, while the scheduler is responsible for making decisions about process selection based on scheduling algorithms and policies.
FAQs related to the Difference Between Dispatcher and Scheduler
Here are some of the FAQs related to Difference Between Dispatcher and Scheduler:
1. What is the primary function of the dispatcher?
The dispatcher is responsible for the actual transfer of control between processes, performing tasks such as context switching and resource allocation.
2. What is the role of the scheduler in an operating system?
The scheduler is responsible for selecting the next process to run based on scheduling algorithms and policies, managing process selection and resource management at a higher level.
3. How does the dispatcher differ from the scheduler in terms of operation level?
The dispatcher operates at a lower level, managing process execution directly, while the scheduler operates at a higher level, making decisions about process selection and resource management.
4. How often is the dispatcher executed?
The dispatcher is executed every time a context switch occurs, which can happen frequently during the execution of a program.
5. Can the scheduler’s decisions affect system performance?
Yes, the scheduler’s decisions can affect the perceived performance of the system by users, as it determines the order in which processes are executed.