Short-Term Scheduler
The short-term scheduler selects processes from the ready queue that are residing in the main memory and allocates CPU to one of them. Thus, it plans the scheduling of the processes that are in a ready state. It is also known as a CPU scheduler. As compared to long-term schedulers, a short-term scheduler has to be used very often i. e. the frequency of execution of short-term schedulers is high. The short-term scheduler is invoked whenever an event occurs. Such an event may lead to the interruption of the current process or it may provide an opportunity to preempt the currently running process in favor of another. The example of such events are:
- Clock ticks (time-based interrupts)
- I/O interrupts and 1/0 completions
- Operating system calls
- Sending and receiving of signals
- Activation of the interactive program
Difference between Short-Term, Medium Term, and Long-Term Scheduler
Process scheduling is an important activity done by the process manager to remove the process from the CPU and schedule the next process, the process removal and dispatch are based on multiple factors like process completion, priority, I/O requirement, etc. Process scheduling plays an important role in Multiprogramming operating systems.
There are mainly three types of schedulers in operating systems, which are: Short-term schedulers, medium-term schedulers, and long-term schedulers. In this article, we are going to discuss about difference between these schedulers.