Explain Rate monotonic real time scheduling algorithmswith example.

Rate Monotonic Scheduling (RMS) is a priority algorithm used for real-time operating systems. It is a static priority pre-emptive scheduling algorithm, which means the priorities are assigned before execution and the highest priority task pre-empts the lower priority tasks.

Here's a step-by-step explanation of how it works:

1. Task Prioritization: In RMS, tasks are assigned priorities according to their cycle time, i.e., the time period between two consecutive instances of the same task. The task with the shortest cycle time gets the highest priority, and the task with the longest cycle time gets the lowest priority.

2. Task Execution: When a task arrives, it is executed according to its priority. If a higher priority task arrives while a lower priority task is being executed, the lower priority task is pre-empted, and the higher priority task is executed.

3. Task Pre-emption: If a task is pre-empted, it is put back in the queue and its execution is resumed when all higher priority tasks have been executed.

4. Task Completion: Once a task is completed, it is removed from the queue. If there are no tasks in the queue, the processor remains idle until a new task arrives.

Let's consider an example:

Suppose we have three tasks T1, T2, and T3 with cycle times of 5ms, 10ms, and 15ms respectively. According to RMS, T1 will have the highest priority and T3 will have the lowest priority.

If all tasks arrive at the same time, T1 will be executed first. If T2 arrives while T1 is being executed, T1 will continue its execution because it has a higher priority. If T3 arrives while T1 is being executed, T1 will still continue its execution. Once T1 is completed, T2 will be executed next, and finally, T3 will be executed.

This is a basic explanation of how the Rate Monotonic Scheduling algorithm works. It's important to note that RMS assumes all tasks are independent and doesn't account for tasks that are interdependent or require synchronization.