先决条件 – 进程调度程序
长期调度程序也称为作业调度程序。长期调度器对选择到系统进行处理的程序进行调节。在这种情况下,程序在队列中设置,并根据要求选择最好的一项作业,并从作业池中获取进程。它规定了多道程序(DOM)的程度。
短期调度程序也称为CPU 调度程序。短期调度程序确保哪个程序适合或重要处理。它规定了较少的 DOM(多程序设计程度)。
长期和短期调度程序之间的区别:
S.NO | Long-Term Scheduler | Short-Term Scheduler |
---|---|---|
1. | Long-Term Scheduler takes the process from job pool. | Short-Term Scheduler takes the process from ready queue. |
2. | Long-Term Scheduler is also known as Job Scheduler. | Short-Term Scheduler is also known as CPU Scheduler. |
3. | In Long-Term Scheduler, the programs are setup in the queue and as per the requirement the best one job is selected. | In Short-Term Scheduler no such queue is exist. |
4. | It regulates the more DOM (Degree of Multi-programming). | It regulates the less DOM (Degree of Multi-programming). |
5. | It regulates the programs which are selected to system for processing. | It ensures which program is suitable or important for processing. |
6. | Speed is less than the short-term scheduler. | Speed is very fast as compared to long-term scheduler. |
7. | Long-Term Scheduler changes the process state from New to Ready. | Short-Term Scheduler changes the process state from Ready to Running. |
8. | Time-sharing operating systems have no long-term scheduler. | It may be minimal in time-sharing system. |
9. | It select a good process, mix of I/O bound and CPU bound. | It select a new process for a CPU quite frequently. |