CPU and IO Bound Processes:

If process is having lots of CPU operation then it is called CPU bound process. Similarly, If process is having lots of IO operation then it is called IO bound process.

Types of schedulers:

1.      Long term – performance – Makes decision about how many processes should be made to stay in the ready state this decides the degree of multiprogramming. Once decision is taken it lasts for long time hence called long term scheduler.

2.      Short term – Context switching time – Short term scheduler will decide which process to be executed next and then it will call dispatcher. Dispatcher is a software that moves process from ready to run and vice versa. In other words, it is context switching.

3.      Medium term – Swapping time – Suspension decision is taken by medium term scheduler. Medium term scheduler is used for swapping that is moving the process from main memory to secondary and vice versa.

Multiprogramming

We have many processes ready to run. There are two types of multiprogramming:

1.      Pre-emption – Process is forcefully removed from CPU. Pre-emption is also called as time sharing or multitasking.

2.      Non pre-emption – Processes are not removed until they complete the execution.

Degree of multiprogramming

The number of process that can reside in the ready state at maximum decides the degree of multiprogramming, e.g., if degree of programming = 100 means 100 processes can reside in the ready state at maximum.