Priority Inversion is a problem while Priority Inheritance is a solution. Literally, Priority Inversion means that priority of tasks get inverted and Priority Inheritance means that priority of tasks get inherited. Both of these phenomena happen in priority scheduling. Basically, in Priority Inversion, higher priority task (H) ends up waiting for middle priority task (M) when H is sharing critical section with lower priority task (L) and L is already in critical section. Effectively, H waiting for M results in inverted priority i.e. Priority Inversion. One of the solution for this problem is Priority Inheritance. In Priority Inheritance, when L is in critical section, L inherits priority of H at the time when H starts pending for critical section. By doing so, M doesn’t interrupt L and H doesn’t wait for M to finish. Please note that inheriting of priority is done temporarily i.e. L goes back to its old priority when L comes out of critical section.
Best known Priority Inversion Problem in Computer Science Histroy:
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