Difference between dispatcher and scheduler

Role: Selects processes from the ready queue and loads them into memory for execution.
Purpose: Aims to balance system resources and optimize performance (e.g., maximize CPU utilization, minimize response time).
Frequency: Runs relatively less frequently.
Types of Scheduling:
- Long-Term Scheduler (Job Scheduler): Decides which jobs or processes from the job pool are admitted into the ready queue.
- Short-Term Scheduler (CPU Scheduler): Selects which of the ready processes should be executed next by the CPU. It's invoked frequently.
- Medium-Term Scheduler: Often involved in swapping processes out of main memory (and back in) to manage the degree of multiprogramming.
Action: Deals with queues and policies for process selection.

Role: Gives control of the CPU to the process selected by the Short-Term Scheduler.
Purpose: Facilitates context switching and allows the selected process to run.
Frequency: Runs very frequently, typically whenever a process needs to be switched out for another.
Functionalities:
- Context Switch: Saves the state of the old process and loads the saved state of the new process.
- Switching to User Mode: Changes the CPU mode from kernel mode to user mode.
- Jumping to the proper location in the user program: Restarts the user program at the correct instruction.
Dispatch Latency: The time it takes for the dispatcher to stop one process and start another running. It's the time taken during context switching.
Action: Provides the mechanism for actual execution of the selected process.