Difference Between Preemptive and Non Preemptive Scheduling in Tabular Form
Contents
Comparison Between Preemptive and Non-Preemptive Scheduling
The basic difference between preemptive and non-preemptive scheduling is that Preemptive scheduling can be preempted that is a process that can be scheduled. In non-preemptive scheduling process cannot be scheduled. The Scheduling algorithms can be divided into two categories:
- Preemptive Scheduling
- Non-Preemptive Scheduling
Comparison Chart
| Preemptive scheduling | Non-Preemptive Scheduling |
|---|---|
| Preemptive scheduling allows a process to be interrupted in the midst of its execution, taking the CPU away and allocating it to another process. | Non-preemptive scheduling ensures that a process relinquishes control of the CPU only when it finishes with its current CPU burst. |
| Preemptive scheduling incurs a cost associated with access shared data. | Non-preemptive scheduling does not increase the cost. |
| It also affects the design of the operating Kernel. | It does not affect the design of the OS system Kernel. |
| Preemptive scheduling is more complex. | Simple, but very inefficient. |
| Example: Round robin method. | Example: First come first serve method. |
Preemptive scheduling
- A scheduling method that interrupts the processing of a and transfers the CPU to another process is called a preemptive CPU scheduling.
- The process switches from the running state to the ready state and waiting for the state to the ready state.
- Preemptive scheduling increases the cost and it has higher overheads. This scheduling method is useful only in the high priority Processes require rapid response.
Non-Preemptive Scheduling
- Non-preemptive operation usually proceeds towards completion uninterrupted.
- Once the system has assigned a processor to a process the system cannot remove that processor from the process.
- The process switches from the running state to the waiting state and termination of a process.
- It is simple to implement.
- It requires some hardware platforms. This method is attractive because of its simplicity. Windows 3.1 and the Apple Macintosh operating system use this scheduling method.