What is difference between a scheduler and a dispatcher?

Answer 1

DISPATCHER?

The dispatcher is the module that gives control of the CPU to the process selected by the short-time scheduler(selects from among the processes that are ready to execute).

The function involves :

Swithching context

Switching to user mode

Jumping to the proper location in the user program to restart that program.

SCHEDULER? Normally there are 3 types of schedulers are available in operating systems.

1. Long term scheduler

2. Mid term scheduler

3. Short term scheduler

The short term scheduler is also called as the dispatcher which selects the process from the waiting queue and allocates the CPU to that process.

Whereas the Long term scheduler (Admission scheduler) decides which process should be placed in the main memory and updates the waiting queue. This long scheduler is important in the large bound systems like super computers and may not be used frequently as the short term scheduler.

The mis term scheduler available in all systems which is responsible for the swapping in and out operations which means loading the process into, main memory from secondary memory (swap in) and take out the process from main memory and store it into the secondary memory (swap out).