There are a number of different types of scan scheduling techniques. These include, but are not limited to, CPU scheduling, pre-emptive scheduling and non pre-emptive scheduling.
CPU stands for Central Processing Unit. This is the term used to describe the part of a computer which performs the basic operations of a computer system, such as running a program or performing a calculation. A process on a computer, such as opening a program or saving a file, requires what is known as "CPU time" - the central processing unit must spend an amount of time processing the action that the computer is about to perform.
CPU scheduling, therefore, is the system that allows a CPU to dictate the order in which processes will receive CPU time, and therefore, the order in which processes will be completed. There are a number of different ways in which a CPU can schedule a group of different processes - for example, the smallest processes could receive CPU time before the larger ones, or the processes which were executed by the user first could be dealt with first.
Non pre-emptive scheduling is where a process has the complete attention of the CPU until the process is either terminated or completed. Only when the process has finished its time in the CPU can another process enter the CPU - the CPU time of a process cannot be interrupted.
In a pre-emptive scheduling technique, a process in the CPU can be replaced with another process, if the second process is deemed by the computer to have a higher priority than the first. This means that a process could enter and leave the CPU a number of times before it is completed, because higher-priority processes have constantly pushed the first process out of the CPU.
- CPU scheduling
CPU stands for Central Processing Unit. This is the term used to describe the part of a computer which performs the basic operations of a computer system, such as running a program or performing a calculation. A process on a computer, such as opening a program or saving a file, requires what is known as "CPU time" - the central processing unit must spend an amount of time processing the action that the computer is about to perform.
CPU scheduling, therefore, is the system that allows a CPU to dictate the order in which processes will receive CPU time, and therefore, the order in which processes will be completed. There are a number of different ways in which a CPU can schedule a group of different processes - for example, the smallest processes could receive CPU time before the larger ones, or the processes which were executed by the user first could be dealt with first.
- Non pre-emptive scheduling
Non pre-emptive scheduling is where a process has the complete attention of the CPU until the process is either terminated or completed. Only when the process has finished its time in the CPU can another process enter the CPU - the CPU time of a process cannot be interrupted.
- Pre-emptive scheduling
In a pre-emptive scheduling technique, a process in the CPU can be replaced with another process, if the second process is deemed by the computer to have a higher priority than the first. This means that a process could enter and leave the CPU a number of times before it is completed, because higher-priority processes have constantly pushed the first process out of the CPU.
