Real time, Rate Monotonic Scheduling (RMS), Earliest Deadline First (EDF) algorithm

Real time scheduling: Real time scheduling is the scheduling of multiple processes having different sets of deadlines. In this type of scheduling each process competes for the CPU time and things like frequency of a process to run, deadlines, etc. are decided in real time.

Rate Monotonic Scheduling (RMS): Rate Monotonic Scheduling is a real time preemptive scheduling algorithm.  It is used for processes which meets the below given conditions:

1) Processes should be periodic and there should be a time period for every process.

2) Every process must require same amount of CPU time on each burst.

3) Every process should be independent.

4) If a process is not periodic, then it should not have a deadline.

Earliest Deadline First (EDF) Scheduling: It is a type of real time scheduling algorithm. In EDF scheduling algorithm, the first two conditions of the RMS algorithm is not required. In EDF, processes are sorted by using their deadlines. A process which has the earliest deadline is run first. If a new process is ready, its deadline is checked. If the deadline is before the running process, then the new process pre-empts the running process.

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