CPU scheduling in operating system-computer world

  CPU scheduling in operating system

CPU scheduling :

 Whenever the CPU becomes idle, the operating system must select one of the processes. The selection process is carried by the short-term scheduler. The scheduler selects a process from the processes in memory that that are ready to execute and allocate the CPU to that process. The objective of time sharing is to skip the CPU among processes that user interact with each program while the program is in running position. As we discuss above the process scheduler selects an process for execution on the CPU. There will never more then one running process for a single processor system. If there are many processes, the process will have to wait until the CPU is free CPU Scheduling is basis of multi-programming operating system. In CPU scheduling many processes are kept in memory at a time. The CPU scheduler select a process from the many processes. The process scheduler scheduled different processes to be assigned to the CPU based on particular scheduling algorithm which we are going to discuss 

1. First come, first served (FCFS)
2. Shortest job first (SJF)
3. Priority scheduling 

In complex operating system there are three types of schedulers 

Long term scheduler

1. It is a job scheduler and it's speed is lesser then term scheduler.
2. Short-term schedule. 
3. It a CPU scheduler and it's speed is fastest among other two scheduler.
4. Medium-term scheduler 
5. It is a process swapping scheduler and it's speed is in between both short & long term scheduler.