Static priorities are a scheduling technique where each task is assigned a priority value based on its importance or urgency. These priorities are determined at design-time and remain fixed throughout the execution of the system. The task with the highest priority is always executed first, regardless of the current state of the system.

RM (Rate Monotonic) scheduling is an example of a scheduling algorithm that is based on static priorities. In RM scheduling, tasks are assigned priorities inversely proportional to their periods. The task with the shortest period has the highest priority. This means that the task with the shortest deadline is always executed first.

Explanation:
RM scheduling assigns priorities to tasks based on their periods. The task with the shortest period has the highest priority, and the task with the longest period has the lowest priority. This is because tasks with shorter periods have more frequent deadlines and need to be executed more often to meet their deadlines.

RM scheduling is an example of static priority scheduling because the priorities assigned to tasks do not change during runtime. Once the priorities are assigned based on the task periods, they remain fixed throughout the execution of the system.

Example:
Let's consider an example to illustrate RM scheduling based on static priorities. Suppose we have three periodic tasks with the following periods:

Task A: Period = 10 ms
Task B: Period = 20 ms
Task C: Period = 40 ms

According to RM scheduling, Task A, with the shortest period, will have the highest priority, followed by Task B, and then Task C. The priorities assigned to the tasks are as follows:

Task A: Priority = 3 (highest priority)
Task B: Priority = 2
Task C: Priority = 1 (lowest priority)

During the execution of the system, Task A will always be executed first, followed by Task B, and then Task C. This order is determined by the static priorities assigned to the tasks based on their periods.

In conclusion, RM scheduling is an example of a scheduling algorithm based on static priorities. The priorities assigned to tasks are determined at design-time and remain fixed throughout the execution of the system.