Mason <[email protected]> wrote:
> AFAIU, mutexes do not make a system immune to priority inversion.
>
> Consider 3 processes of increasing priority L, M, H.
>
> Suppose L locks a mutex; then H waits for the mutex; then M starts
> running and preempts L : H will never run, as long as M runs.
That's exactly the case we want to be able to fix by using mutexes instead of
binary semaphores.
> Unless you were thinking of specific implementations of mutexes
> (priority mutexes) which temporarily boost the priority of tasks
> that lock that specific mutex?
Of course, if your mutex implementation doesn't support this, you can use
binary semaphores as well. However, in all embedded ("realtime") OSes I've
worked with, L gets the priority of H while L owns the mutex that H waits for.
Simon
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